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Hawes EM, Rahim M, Haratipour Z, Orun AR, O'Rourke ML, Oeser JK, Kim K, Claxton DP, Blind RD, Young JD, O'Brien RM. Biochemical and metabolic characterization of a G6PC2 inhibitor. Biochimie 2024; 222:109-122. [PMID: 38431189 DOI: 10.1016/j.biochi.2024.02.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 02/28/2024] [Accepted: 02/29/2024] [Indexed: 03/05/2024]
Abstract
Three glucose-6-phosphatase catalytic subunits, that hydrolyze glucose-6-phosphate (G6P) to glucose and inorganic phosphate, have been identified, designated G6PC1-3, but only G6PC1 and G6PC2 have been implicated in the regulation of fasting blood glucose (FBG). Elevated FBG has been associated with multiple adverse clinical outcomes, including increased risk for type 2 diabetes and various cancers. Therefore, G6PC1 and G6PC2 inhibitors that lower FBG may be of prophylactic value for the prevention of multiple conditions. The studies described here characterize a G6PC2 inhibitor, designated VU0945627, previously identified as Compound 3. We show that VU0945627 preferentially inhibits human G6PC2 versus human G6PC1 but activates human G6PC3. VU0945627 is a mixed G6PC2 inhibitor, increasing the Km but reducing the Vmax for G6P hydrolysis. PyRx virtual docking to an AlphaFold2-derived G6PC2 structural model suggests VU0945627 binds two sites in human G6PC2. Mutation of residues in these sites reduces the inhibitory effect of VU0945627. VU0945627 does not inhibit mouse G6PC2 despite its 84% sequence identity with human G6PC2. Mutagenesis studies suggest this lack of inhibition of mouse G6PC2 is due, in part, to a change in residue 318 from histidine in human G6PC2 to proline in mouse G6PC2. Surprisingly, VU0945627 still inhibited glucose cycling in the mouse islet-derived βTC-3 cell line. Studies using intact mouse liver microsomes and PyRx docking suggest that this observation can be explained by an ability of VU0945627 to also inhibit the G6P transporter SLC37A4. These data will inform future computational modeling studies designed to identify G6PC isoform-specific inhibitors.
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Affiliation(s)
- Emily M Hawes
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Mohsin Rahim
- Department of Chemical and Biomolecular Engineering, Vanderbilt School of Engineering, Nashville, TN, 37232, USA
| | - Zeinab Haratipour
- Austin Peay State University, 601 College St, Clarksville, TN 37044, USA; Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Abigail R Orun
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Margaret L O'Rourke
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - James K Oeser
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Kwangho Kim
- Department of Chemistry, Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, 37232, USA
| | - Derek P Claxton
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Ray D Blind
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Jamey D Young
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA; Department of Chemical and Biomolecular Engineering, Vanderbilt School of Engineering, Nashville, TN, 37232, USA
| | - Richard M O'Brien
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA.
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Rossen J, Shi H, Strober BJ, Zhang MJ, Kanai M, McCaw ZR, Liang L, Weissbrod O, Price AL. MultiSuSiE improves multi-ancestry fine-mapping in All of Us whole-genome sequencing data. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2024:2024.05.13.24307291. [PMID: 38798542 PMCID: PMC11118590 DOI: 10.1101/2024.05.13.24307291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Leveraging data from multiple ancestries can greatly improve fine-mapping power due to differences in linkage disequilibrium and allele frequencies. We propose MultiSuSiE, an extension of the sum of single effects model (SuSiE) to multiple ancestries that allows causal effect sizes to vary across ancestries based on a multivariate normal prior informed by empirical data. We evaluated MultiSuSiE via simulations and analyses of 14 quantitative traits leveraging whole-genome sequencing data in 47k African-ancestry and 94k European-ancestry individuals from All of Us. In simulations, MultiSuSiE applied to Afr47k+Eur47k was well-calibrated and attained higher power than SuSiE applied to Eur94k; interestingly, higher causal variant PIPs in Afr47k compared to Eur47k were entirely explained by differences in the extent of LD quantified by LD 4th moments. Compared to very recently proposed multi-ancestry fine-mapping methods, MultiSuSiE attained higher power and/or much lower computational costs, making the analysis of large-scale All of Us data feasible. In real trait analyses, MultiSuSiE applied to Afr47k+Eur94k identified 579 fine-mapped variants with PIP > 0.5, and MultiSuSiE applied to Afr47k+Eur47k identified 44% more fine-mapped variants with PIP > 0.5 than SuSiE applied to Eur94k. We validated MultiSuSiE results for real traits via functional enrichment of fine-mapped variants. We highlight several examples where MultiSuSiE implicates well-studied or biologically plausible fine-mapped variants that were not implicated by other methods.
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Wu KCH, Liu L, Xu A, Chan YH, Cheung BMY. Shared genetic architecture between periodontal disease and type 2 diabetes: a large scale genome-wide cross-trait analysis. Endocrine 2024:10.1007/s12020-024-03766-8. [PMID: 38460073 DOI: 10.1007/s12020-024-03766-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Accepted: 02/27/2024] [Indexed: 03/11/2024]
Abstract
PURPOSE To investigate the relationship between abnormal glucose metabolism, type 2 diabetes (T2D), and periodontal disease (PER) independent of Body Mass Index (BMI), we employed a genome-wide cross-trait approach to clarify the association. METHODS Our study utilized the most extensive genome-wide association studies conducted for populations of European ancestry, including PER, T2D, fasting glucose, fasting insulin, 2-hour glucose after an oral glucose challenge, HOMA-β, HOMA-IR (unadjusted or adjusted for BMI) and HbA1c. RESULTS With this approach, we were able to identify pleiotropic loci, establish expression-trait associations, and quantify global and local genetic correlations. There was a significant positive global genetic correlation between T2D (rg = 0.261, p = 2.65 × 10-13), HbA1c (rg = 0.182, p = 4.14 × 10-6) and PER, as well as for T2D independent of BMI (rg = 0.158, p = 2.34 × 10-6). A significant local genetic correlation was also observed between PER and glycemic traits or T2D. We also identified 62 independent pleiotropic loci that impact both PER and glycemic traits, including T2D. Nine significant pathways were identified between the shared genes between T2D, glycemic traits and PER. Genetically liability of HOMA-βadjBMI was causally associated with the risk of PER. CONCLUSION Our research has revealed a genetic link between T2D, glycemic traits, and PER that is influenced by biological pleiotropy. Notably, some of these links are not related to BMI. Our research highlights an underlying link between patients with T2D and PER, regardless of their BMI.
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Affiliation(s)
- Kevin Chun Hei Wu
- Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Lin Liu
- Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Aimin Xu
- Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
- State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Yap Hang Chan
- Division of Cardiology, Queen Mary Hospital, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Bernard Man Yung Cheung
- Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.
- State Key Laboratory of Pharmaceutical Biotechnology, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.
- Institute of Cardiovascular Science and Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.
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Hawes E, Claxton D, Oeser J, O’Brien R. Identification of structural motifs critical for human G6PC2 function informed by sequence analysis and an AlphaFold2-predicted model. Biosci Rep 2024; 44:BSR20231851. [PMID: 38095063 PMCID: PMC10776900 DOI: 10.1042/bsr20231851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 11/22/2023] [Accepted: 12/12/2023] [Indexed: 01/10/2024] Open
Abstract
G6PC2 encodes a glucose-6-phosphatase (G6Pase) catalytic subunit, primarily expressed in pancreatic islet β cells, which modulates the sensitivity of insulin secretion to glucose and thereby regulates fasting blood glucose (FBG). Mutational analyses were conducted to validate an AlphaFold2 (AF2)-predicted structure of human G6PC2 in conjunction with a novel method to solubilize and purify human G6PC2 from a heterologous expression system. These analyses show that residues forming a predicted intramolecular disulfide bond are essential for G6PC2 expression and that residues forming part of a type 2 phosphatidic acid phosphatase (PAP2) motif are critical for enzyme activity. Additional mutagenesis shows that residues forming a predicted substrate cavity modulate enzyme activity and substrate specificity and residues forming a putative cholesterol recognition amino acid consensus (CRAC) motif influence protein expression or enzyme activity. This CRAC motif begins at residue 219, the site of a common G6PC2 non-synonymous single-nucleotide polymorphism (SNP), rs492594 (Val219Leu), though the functional impact of this SNP is disputed. In microsomal membrane preparations, the L219 variant has greater activity than the V219 variant, but this difference disappears when G6PC2 is purified in detergent micelles. We hypothesize that this was due to a differential association of the two variants with cholesterol. This concept was supported by the observation that the addition of cholesteryl hemi-succinate to the purified enzymes decreased the Vmax of the V219 and L219 variants ∼8-fold and ∼3 fold, respectively. We anticipate that these observations should support the rational development of G6PC2 inhibitors designed to lower FBG.
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Affiliation(s)
- Emily M. Hawes
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, U.S.A
| | - Derek P. Claxton
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, U.S.A
| | - James K. Oeser
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, U.S.A
| | - Richard M. O’Brien
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, U.S.A
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Guo J, Yan E, He L, Wang Y, Xiang Y, Zhang P, Liu X, Yin J. Dietary Supplementation with Lauric Acid Improves Aerobic Endurance in Sedentary Mice via Enhancing Fat Mobilization and Glyconeogenesis. J Nutr 2023; 153:3207-3219. [PMID: 37696395 DOI: 10.1016/j.tjnut.2023.09.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 08/18/2023] [Accepted: 09/07/2023] [Indexed: 09/13/2023] Open
Abstract
BACKGROUND Lauric acid (LA), a major, natural, medium-chain fatty acid, is considered an efficient energy substrate for intense exercise and in patients with long-chain fatty acid β-oxidation disorders. However, few studies have focused on the role of LA in exercise performance and related glucolipid metabolism in vivo. OBJECTIVES We aimed to investigate the effect of dietary supplementation with LA on exercise performance and related metabolic mechanisms. METHODS Male C57BL/6N mice (14 wk old) were fed a basal diet or a diet containing 1% LA, and a series of exercise tests, including a high-speed treadmill test, aerobic endurance exercises, a 4-limb hanging test, and acute aerobic exercises, were performed. RESULTS Dietary supplementation with 1.0% LA accelerated the recovery from fatigue after explosive exercise (P < 0.05) and improved aerobic endurance and muscle strength in sedentary mice (P = 0.039). Lauric acid intake not only changed muscle fatty acid profiles, including increases in C12:0 and n-6/n-3 PUFAs (P < 0.001) and reductions in C18:0, C20:4n-6, C22:6n-3, and n-3 PUFAs (P < 0.05) but also enhanced fat mobilization from adipose tissue and fatty acid oxidation in the liver, at least partly via the AMP-activated protein kinase-acetyl CoA carboxylase pathway (P < 0.05). Likewise, LA supplementation promoted liver glyconeogenesis and conserved muscular glycogen during acute aerobic exercise (P < 0.05), which was accompanied by an increase in the mitochondrial DNA copy number and Krebs cycle activity in skeletal muscle (P < 0.05). CONCLUSIONS Dietary supplemental LA serves as an efficient energy substrate for sedentary mice to improve aerobic exercise endurance and muscle strength through regulation of glucolipid metabolism. These findings imply that LA supplementation might be a promising nutritional strategy to improve aerobic exercise performance in sedentary people.
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Affiliation(s)
- Jianxin Guo
- State Key Laboratory of Animal Nutrition and Feeding, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Enfa Yan
- State Key Laboratory of Animal Nutrition and Feeding, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Linjuan He
- State Key Laboratory of Animal Nutrition and Feeding, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Yubo Wang
- State Key Laboratory of Animal Nutrition and Feeding, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Yifan Xiang
- State Key Laboratory of Animal Nutrition and Feeding, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Pengguang Zhang
- State Key Laboratory of Animal Nutrition and Feeding, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Xiangze Liu
- State Key Laboratory of Animal Nutrition and Feeding, College of Animal Science and Technology, China Agricultural University, Beijing, China
| | - Jingdong Yin
- State Key Laboratory of Animal Nutrition and Feeding, College of Animal Science and Technology, China Agricultural University, Beijing, China; Molecular design breeding Frontier Science Center of the Ministry of Education, China.
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Keller MP, Hawes EM, Schueler KL, Stapleton DS, Mitok KA, Simonett SP, Oeser JK, Sampson LL, Attie AD, Magnuson MA, O’Brien RM. An Enhancer Within Abcb11 Regulates G6pc2 in C57BL/6 Mouse Pancreatic Islets. Diabetes 2023; 72:1621-1628. [PMID: 37552875 PMCID: PMC10588275 DOI: 10.2337/db23-0215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 08/01/2023] [Indexed: 08/10/2023]
Abstract
G6PC2 is predominantly expressed in pancreatic islet β-cells where it encodes a glucose-6-phosphatase catalytic subunit that modulates the sensitivity of insulin secretion to glucose by opposing the action of glucokinase, thereby regulating fasting blood glucose (FBG). Prior studies have shown that the G6pc2 promoter alone is unable to confer sustained islet-specific gene expression in mice, suggesting the existence of distal enhancers that regulate G6pc2 expression. Using information from both mice and humans and knowledge that single nucleotide polymorphisms (SNPs) both within and near G6PC2 are associated with variations in FBG in humans, we identified several putative enhancers 3' of G6pc2. One region, herein referred to as enhancer I, resides in the 25th intron of Abcb11 and binds multiple islet-enriched transcription factors. CRISPR-mediated deletion of enhancer I in C57BL/6 mice had selective effects on the expression of genes near the G6pc2 locus. In isolated islets, G6pc2 and Spc25 expression were reduced ∼50%, and Gm13613 expression was abolished, whereas Cers6 and nostrin expression were unaffected. This partial reduction in G6pc2 expression enhanced islet insulin secretion at basal glucose concentrations but did not affect FBG or glucose tolerance in vivo, consistent with the absence of a phenotype in G6pc2 heterozygous C57BL/6 mice. ARTICLE HIGHLIGHTS
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Affiliation(s)
- Mark P. Keller
- Department of Biochemistry, University of Wisconsin–Madison, Madison, WI
| | - Emily M. Hawes
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | | | | | - Kelly A. Mitok
- Department of Biochemistry, University of Wisconsin–Madison, Madison, WI
| | - Shane P. Simonett
- Department of Biochemistry, University of Wisconsin–Madison, Madison, WI
| | - James K. Oeser
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Leesa L. Sampson
- Center for Stem Cell Biology, Vanderbilt University School of Medicine, Nashville, TN
| | - Alan D. Attie
- Department of Biochemistry, University of Wisconsin–Madison, Madison, WI
- Department of Chemistry, University of Wisconsin–Madison, Madison, WI
- Department of Medicine, University of Wisconsin–Madison, Madison, WI
| | - Mark A. Magnuson
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
- Center for Stem Cell Biology, Vanderbilt University School of Medicine, Nashville, TN
| | - Richard M. O’Brien
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
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Mathisen AF, Abadpour S, Legøy TA, Paulo JA, Ghila L, Scholz H, Chera S. Global proteomics reveals insulin abundance as a marker of human islet homeostasis alterations. Acta Physiol (Oxf) 2023; 239:e14037. [PMID: 37621186 PMCID: PMC10592125 DOI: 10.1111/apha.14037] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Revised: 08/07/2023] [Accepted: 08/10/2023] [Indexed: 08/26/2023]
Abstract
AIM The variation in quality between the human islet samples represents a major problem for research, especially when used as control material. The assays assessing the quality of human islets used in research are non-standardized and limited, with many important parameters not being consistently assessed. High-throughput studies aimed at characterizing the diversity and segregation markers among apparently functionally healthy islet preps are thus a requirement. Here, we designed a pilot study to comprehensively identify the diversity of global proteome signatures and the deviation from normal homeostasis in randomly selected human-isolated islet samples. METHODS By using Tandem Mass Tag 16-plex proteomics, we focused on the recurrently observed disparity in the detected insulin abundance between the samples, used it as a segregating parameter, and analyzed the correlated changes in the proteome signature and homeostasis by pathway analysis. RESULTS In this pilot study, we showed that insulin protein abundance is a predictor of human islet homeostasis and quality. This parameter is independent of other quality predictors within their acceptable range, thus being able to further stratify islets samples of apparent good quality. Human islets with low amounts of insulin displayed changes in their metabolic and signaling profile, especially in regard to energy homeostasis and cell identity maintenance. We further showed that xenotransplantation into diabetic hosts is not expected to improve the pre-transplantation signature, as it has a negative effect on energy balance, antioxidant activity, and islet cell identity. CONCLUSIONS Insulin protein abundance predicts significant changes in human islet homeostasis among random samples of apparently good quality.
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Affiliation(s)
- Andreas F. Mathisen
- Mohn Research Center for Diabetes Precision Medicine, Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Shadab Abadpour
- Hybrid Technology Hub-Centre of Excellence, Faculty of Medicine, University of Oslo, Norway
- Institute for Surgical Research and Department of Transplant Medicine, Oslo University Hospital, Oslo, Norway
| | - Thomas Aga Legøy
- Mohn Research Center for Diabetes Precision Medicine, Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Joao A. Paulo
- Department of Cell Biology, Harvard Medical School, Boston, MA, USA
| | - Luiza Ghila
- Mohn Research Center for Diabetes Precision Medicine, Department of Clinical Science, University of Bergen, Bergen, Norway
| | - Hanne Scholz
- Hybrid Technology Hub-Centre of Excellence, Faculty of Medicine, University of Oslo, Norway
- Institute for Surgical Research and Department of Transplant Medicine, Oslo University Hospital, Oslo, Norway
| | - Simona Chera
- Mohn Research Center for Diabetes Precision Medicine, Department of Clinical Science, University of Bergen, Bergen, Norway
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Grenko CM, Bonnycastle LL, Taylor HJ, Yan T, Swift AJ, Robertson CC, Narisu N, Erdos MR, Collins FS, Taylor DL. Single-cell transcriptomic profiling of human pancreatic islets reveals genes responsive to glucose exposure over 24 hours. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.06.543931. [PMID: 37333221 PMCID: PMC10274787 DOI: 10.1101/2023.06.06.543931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
Disruption of pancreatic islet function and glucose homeostasis can lead to the development of sustained hyperglycemia, beta cell glucotoxicity, and ultimately type 2 diabetes (T2D). In this study, we sought to explore the effects of hyperglycemia on human pancreatic islet (HPI) gene expression by exposing HPIs from two donors to low (2.8mM) and high (15.0mM) glucose concentrations over 24 hours, assaying the transcriptome at seven time points using single-cell RNA sequencing (scRNA-seq). We modeled time as both a discrete and continuous variable to determine momentary and longitudinal changes in transcription associated with islet time in culture or glucose exposure. Across all cell types, we identified 1,528 genes associated with time, 1,185 genes associated with glucose exposure, and 845 genes associated with interaction effects between time and glucose. We clustered differentially expressed genes across cell types and found 347 modules of genes with similar expression patterns across time and glucose conditions, including two beta cell modules enriched in genes associated with T2D. Finally, by integrating genomic features from this study and genetic summary statistics for T2D and related traits, we nominate 363 candidate effector genes that may underlie genetic associations for T2D and related traits.
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Affiliation(s)
- Caleb M. Grenko
- Center for Precision Health Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Lori L. Bonnycastle
- Center for Precision Health Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Henry J. Taylor
- Center for Precision Health Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA
- British Heart Foundation Cardiovascular Epidemiology Unit, Department of Public Health and Primary Care, University of Cambridge, Cambridge CB1 8RN, UK
| | - Tingfen Yan
- Center for Precision Health Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Amy J. Swift
- Center for Precision Health Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Catherine C. Robertson
- Center for Precision Health Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Narisu Narisu
- Center for Precision Health Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Michael R. Erdos
- Center for Precision Health Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Francis S. Collins
- Center for Precision Health Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - D. Leland Taylor
- Center for Precision Health Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA
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Miranda MA, Macias-Velasco JF, Schmidt H, Lawson HA. Integrated transcriptomics contrasts fatty acid metabolism with hypoxia response in β-cell subpopulations associated with glycemic control. BMC Genomics 2023; 24:156. [PMID: 36978008 PMCID: PMC10052828 DOI: 10.1186/s12864-023-09232-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 03/07/2023] [Indexed: 03/30/2023] Open
Abstract
BACKGROUND Understanding how heterogeneous β-cell function impacts diabetes is imperative for therapy development. Standard single-cell RNA sequencing analysis illuminates some factors driving heterogeneity, but new strategies are required to enhance information capture. RESULTS We integrate pancreatic islet single-cell and bulk RNA sequencing data to identify β-cell subpopulations based on gene expression and characterize genetic networks associated with β-cell function in obese SM/J mice. We identify β-cell subpopulations associated with basal insulin secretion, hypoxia response, cell polarity, and stress response. Network analysis associates fatty acid metabolism and basal insulin secretion with hyperglycemic-obesity, while expression of Pdyn and hypoxia response is associated with normoglycemic-obesity. CONCLUSIONS By integrating single-cell and bulk islet transcriptomes, our study explores β-cell heterogeneity and identifies novel subpopulations and genetic pathways associated with β-cell function in obesity.
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Affiliation(s)
- Mario A Miranda
- Department of Genetics, Washington University School of Medicine, 660 South Euclid Ave, Campus Box 8232, Saint Louis, MO, 63110, USA
| | - Juan F Macias-Velasco
- Department of Genetics, Washington University School of Medicine, 660 South Euclid Ave, Campus Box 8232, Saint Louis, MO, 63110, USA
| | - Heather Schmidt
- Department of Genetics, Washington University School of Medicine, 660 South Euclid Ave, Campus Box 8232, Saint Louis, MO, 63110, USA
| | - Heather A Lawson
- Department of Genetics, Washington University School of Medicine, 660 South Euclid Ave, Campus Box 8232, Saint Louis, MO, 63110, USA.
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Tremmel DM, Mikat AE, Gupta S, Mitchell SA, Curran AM, Menadue JA, Odorico JS, Sackett SD. Validating expression of beta cell maturation-associated genes in human pancreas development. Front Cell Dev Biol 2023; 11:1103719. [PMID: 36846594 PMCID: PMC9945361 DOI: 10.3389/fcell.2023.1103719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Accepted: 01/16/2023] [Indexed: 02/04/2023] Open
Abstract
The identification of genes associated with human pancreatic beta cell maturation could stimulate a better understanding of normal human islet development and function, be informative for improving stem cell-derived islet (SC-islet) differentiation, and facilitate the sorting of more mature beta cells from a pool of differentiated cells. While several candidate factors to mark beta cell maturation have been identified, much of the data supporting these markers come from animal models or differentiated SC-islets. One such marker is Urocortin-3 (UCN3). In this study, we provide evidence that UCN3 is expressed in human fetal islets well before the acquisition of functional maturation. When SC-islets expressing significant levels of UCN3 were generated, the cells did not exhibit glucose-stimulated insulin secretion, indicating that UCN3 expression is not correlated with functional maturation in these cells. We utilized our tissue bank and SC-islet resources to test an array of other candidate maturation-associated genes, and identified CHGB, G6PC2, FAM159B, GLUT1, IAPP and ENTPD3 as markers with expression patterns that correlate developmentally with the onset of functional maturation in human beta cells. We also find that human beta cell expression of ERO1LB, HDAC9, KLF9, and ZNT8 does not change between fetal and adult stages.
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Affiliation(s)
- Daniel M. Tremmel
- *Correspondence: Daniel M. Tremmel, ; Sara Dutton Sackett, ; Jon S. Odorico,
| | - Anna E. Mikat
- University of Wisconsin-Madison, Department of Surgery, Transplantation Division, Madison, WI, United States
| | - Sakar Gupta
- University of Wisconsin-Madison, Department of Surgery, Transplantation Division, Madison, WI, United States
| | - Samantha A. Mitchell
- University of Wisconsin-Madison, Department of Surgery, Transplantation Division, Madison, WI, United States
| | - Andrew M. Curran
- University of Wisconsin-Madison, Department of Surgery, Transplantation Division, Madison, WI, United States
| | - Jenna A. Menadue
- University of Wisconsin-Madison, Department of Surgery, Transplantation Division, Madison, WI, United States
| | - Jon S. Odorico
- *Correspondence: Daniel M. Tremmel, ; Sara Dutton Sackett, ; Jon S. Odorico,
| | - Sara Dutton Sackett
- *Correspondence: Daniel M. Tremmel, ; Sara Dutton Sackett, ; Jon S. Odorico,
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Peng G, Mosleh E, Yuhas A, Katada K, Cherry C, Golson ML. FOXM1 acts sexually dimorphically to regulate functional β-cell mass. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.12.523673. [PMID: 36711451 PMCID: PMC9882186 DOI: 10.1101/2023.01.12.523673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The transcription factor FOXM1 regulates β-cell proliferation and insulin secretion. Our previous work demonstrates that expressing an activated form of FOXM1 (FOXM1*) in β cells increases β-cell proliferation and mass in aged male mice. Additionally, FOXM1* enhances β-cell function even in young mice, in which no β-cell mass elevation occurs. Here, we demonstrate that FOXM1 acts in a sexually dimorphic manner in the β cell. Expression of FOXM1* in female mouse β cells does not affect β-cell proliferation or glucose tolerance. Transduction of male but not female human islets with FOXM1* enhances insulin secretion in response to elevated glucose. Estrogen contributes to diabetes susceptibility differences between males and females, and the estrogen receptor (ER)α is the primary mediator of β-cell estrogen signaling. We show that FOXM1* can rescue impaired glucose tolerance in female mice with a pancreas-wide ERα deletion. Further, FOXM1 and ERα binding sites overlap with each other and with other β-cell-enriched transcription factors, including ISL1, PAX6, MAF, and GATA. These data indicate that FOMX1 and ERα cooperate to regulate β-cell function and suggest a general mechanism contributing to the lower incidence of diabetes observed in women.
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12
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Kang N, Zhang Y, Xue F, Duan J, Chen F, Cai Y, Luan Q. Periodontitis induced by Porphyromonas gingivalis drives impaired glucose metabolism in mice. Front Cell Infect Microbiol 2022; 12:998600. [PMID: 36299624 PMCID: PMC9588948 DOI: 10.3389/fcimb.2022.998600] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 09/16/2022] [Indexed: 07/22/2023] Open
Abstract
Periodontitis has been demonstrated to be bidirectionally associated with diabetes and has been recognized as a complication of diabetes. As a periodontal pathogen, Porphyromonas gingivalis is a possible pathogen linking periodontal disease and systemic diseases. It has also been found to be involved in the occurrence and development of diabetes. In this study, 6-week-old male C57BL/6 mice were orally administered the P. gingivalis strain ATCC381 for 22 weeks. Histological analysis of the gingival tissue and quantified analysis of alveolar bone loss were performed to evaluate periodontal destruction. Body weight, fasting glucose, glucose tolerance test (GTT), and insulin tolerance test (ITT) were used to evaluate glucose metabolism disorder. We then analyzed the expression profiles of inflammatory cytokines and chemokines in gingival tissue, the liver, and adipose tissue, as well as in serum. The results showed that mice in the P. gingivalis-administered group developed apparent gingival inflammation and more alveolar bone loss compared to the control group. After 22 weeks of P. gingivalis infection, significant differences were observed at 30 and 60 min for the GTT and at 15 min for the ITT. P. gingivalis-administered mice showed an increase in the mRNA expression levels of the pro-inflammatory cytokines (TNF-α, IL-6, IL-17, and IL-23) and chemokines (CCL2, CCL8, and CXCL10) in the gingiva and serum. The expression levels of the glucose metabolism-related genes were also changed in the liver and adipose tissue. Our results indicate that oral administration of P. gingivalis can induce changes in the inflammatory cytokines and chemokines in the gingiva and blood, can lead to alveolar bone loss and to inflammatory changes in the liver and adipose tissues, and can promote glucose metabolism disorder in mice.
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Affiliation(s)
- Ni Kang
- Department of Periodontology, Peking University School and Hospital of Stomatology and National Center of Stomatology and National Clinical Research Center for Oral Diseases and National Engineering Research Center of Oral Biomaterials and Digital Medical Devices and Beijing Key Laboratory of Digital Stomatology and Research Center of Engineering and Technology for Computerized Dentistry Ministry of Health and National Medical Products Administration (NMPA) Key Laboratory for Dental Materials, Beijing, China
- Central Laboratory, Peking University School and Hospital of Stomatology and National Center of Stomatology and National Clinical Research Center for Oral Diseases and National Engineering Research Center of Oral Biomaterials and Digital Medical Devices and Beijing Key Laboratory of Digital Stomatology and Research Center of Engineering and Technology for Computerized Dentistry Ministry of Health and National Medical Products Administration (NMPA) Key Laboratory for Dental Materials, Beijing, China
| | - Yong Zhang
- First Clinical Division, Peking University School and Hospital of Stomatology and National Center of Stomatology and National Clinical Research Center for Oral Diseases and National Engineering Research Center of Oral Biomaterials and Digital Medical Devices and Beijing Key Laboratory of Digital Stomatology and Research Center of Engineering and Technology for Computerized Dentistry Ministry of Health and National Medical Products Administration (NMPA) Key Laboratory for Dental Materials, Beijing, China
| | - Fei Xue
- First Clinical Division, Peking University School and Hospital of Stomatology and National Center of Stomatology and National Clinical Research Center for Oral Diseases and National Engineering Research Center of Oral Biomaterials and Digital Medical Devices and Beijing Key Laboratory of Digital Stomatology and Research Center of Engineering and Technology for Computerized Dentistry Ministry of Health and National Medical Products Administration (NMPA) Key Laboratory for Dental Materials, Beijing, China
| | - Jinyu Duan
- First Clinical Division, Peking University School and Hospital of Stomatology and National Center of Stomatology and National Clinical Research Center for Oral Diseases and National Engineering Research Center of Oral Biomaterials and Digital Medical Devices and Beijing Key Laboratory of Digital Stomatology and Research Center of Engineering and Technology for Computerized Dentistry Ministry of Health and National Medical Products Administration (NMPA) Key Laboratory for Dental Materials, Beijing, China
| | - Fan Chen
- Department of Stomatology, People’s Hospital of Peking University, Beijing, China
| | - Yu Cai
- Department of Periodontology, Peking University School and Hospital of Stomatology and National Center of Stomatology and National Clinical Research Center for Oral Diseases and National Engineering Research Center of Oral Biomaterials and Digital Medical Devices and Beijing Key Laboratory of Digital Stomatology and Research Center of Engineering and Technology for Computerized Dentistry Ministry of Health and National Medical Products Administration (NMPA) Key Laboratory for Dental Materials, Beijing, China
- Central Laboratory, Peking University School and Hospital of Stomatology and National Center of Stomatology and National Clinical Research Center for Oral Diseases and National Engineering Research Center of Oral Biomaterials and Digital Medical Devices and Beijing Key Laboratory of Digital Stomatology and Research Center of Engineering and Technology for Computerized Dentistry Ministry of Health and National Medical Products Administration (NMPA) Key Laboratory for Dental Materials, Beijing, China
| | - Qingxian Luan
- Department of Periodontology, Peking University School and Hospital of Stomatology and National Center of Stomatology and National Clinical Research Center for Oral Diseases and National Engineering Research Center of Oral Biomaterials and Digital Medical Devices and Beijing Key Laboratory of Digital Stomatology and Research Center of Engineering and Technology for Computerized Dentistry Ministry of Health and National Medical Products Administration (NMPA) Key Laboratory for Dental Materials, Beijing, China
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13
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Ahrén B. The Glucose Sensitivity of Insulin Secretion-Lessons from In Vivo and In Vitro Studies in Mice. Biomolecules 2022; 12:biom12070976. [PMID: 35883532 PMCID: PMC9312818 DOI: 10.3390/biom12070976] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2022] [Revised: 06/27/2022] [Accepted: 07/08/2022] [Indexed: 02/05/2023] Open
Abstract
This study explored the relationship between the glucose dose and insulin response from beta cells in vivo and in vitro in mice. Glucose was administered intravenously at different dose levels (from 0 to 0.75 g/kg) in anesthetized C57BL/6J mice, and the glucose and insulin concentrations were determined in samples taken after 50 min. Furthermore, freshly isolated mouse islets were incubated for 60 min in the presence of different concentrations of glucose (from 2.8 to 22.2 mmol/L) and insulin levels were analyzed in the medium. It was found that insulin levels increased after an intravenous injection of glucose with the maximal increase seen after 0.35 g/kg with no further increase after 0.5 or 0.75 g/kg. The acute increase in insulin levels (during the first 5 min) and the maximum glucose level (achieved after 1 min) showed a curvilinear relation with the half-maximal increase in insulin levels achieved at 11.4 mmol/L glucose and the maximal increase in insulin levels at 22.0 mmol/L glucose. In vitro, there was also a curvilinear relation between glucose concentrations and insulin secretion. Half maximal increase in insulin concentrations was achieved at 12.5 mmol/L glucose and the maximal increase in insulin concentrations was achieved at 21.5 mmol/L. Based on these data, we concluded that the glucose-insulin relation was curvilinear both in vivo and in vitro in mice with similar characteristics in relation to which glucose levels that achieve half-maximal and maximal increases in insulin secretion. Besides the new knowledge of knowing these relations, the results have consequences on how to design studies on insulin secretion to obtain the most information.
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Affiliation(s)
- Bo Ahrén
- Department of Clinical Sciences Lund, Lund University, 22185 Lund, Sweden
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14
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Abstract
The ability to maintain normoglycaemia, through glucose-sensitive insulin release, is a key aspect of postnatal beta cell function. However, terminally differentiated beta cell identity does not necessarily imply functional maturity. Beta cell maturation is therefore a continuation of beta cell development, albeit a process that occurs postnatally in mammals. Although many important features have been identified in the study of beta cell maturation, as of yet no unified mechanistic model of beta cell functional maturity exists. Here, we review recent findings about the underlying mechanisms of beta cell functional maturation. These findings include systemic hormonal and nutritional triggers that operate through energy-sensing machinery shifts within beta cells, resulting in primed metabolic states that allow for appropriate glucose trafficking and, ultimately, insulin release. We also draw attention to the expansive synergistic nature of these pathways and emphasise that beta cell maturation is dependent on overlapping regulatory and metabolic networks.
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Affiliation(s)
- Tom Barsby
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
| | - Timo Otonkoski
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
- Children's Hospital, Helsinki University Hospital and University of Helsinki, Helsinki, Finland.
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15
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Udhaya Kumar S, Kamaraj B, Varghese RP, Preethi VA, Bithia R, George Priya Doss C. Mutations in G6PC2 gene with increased risk for development of type 2 diabetes: Understanding via computational approach. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2022; 130:351-373. [PMID: 35534112 DOI: 10.1016/bs.apcsb.2022.02.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
An increase in the fast blood glucose (FBG) levels has been linked to an increased risk of developing a chronic condition, type 2 diabetes (T2D). The mutation in the G6PC2 gene was identified to have a lead role in the modulation of FBG levels. The abnormal regulation of this enzyme influences glucose-stimulated insulin secretion (GSIS), which controls the insulin levels corresponding to the system's glucose level. This study focuses on the mutations at the G6PC2 gene, which cause the variation from normal expression levels and increase the risk of T2D. We examined the non-synonymous single nucleotide polymorphisms (nsSNPs) present in the G6PC2 and subjected them to pathogenicity, stability, residue conservation, and membrane simulation. The individual representation of surrounding amino acids in the mutant (I63T) model showed the loss of hydrophobic interactions compared to the native G6PC2. In addition, the trajectory results from the membrane simulation exhibited reduced stability, and the least compactness was identified for the I63T mutant model. Our study shed light on the structural and conformational changes at the transmembrane region due to the I63T mutation in G6PC2. Additionally, the Gibbs free energy landscape analysis against the two principal components showed structural differences and decreased the conformational stability of the I63T mutant model compared to the native. Like those presented in this study, dynamical simulations may indeed be crucial to comprehending the structural insights of G6PC2 mutations in cardiovascular-associated mortality and T2D.
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Affiliation(s)
- S Udhaya Kumar
- Laboratory of Integrative Genomics, Department of Integrative Biology, School of Bio Sciences and Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, India
| | - Balu Kamaraj
- Department of Neuroscience Technology, College of Applied Medical Sciences, Imam Abdulrahman Bin Faisal University, Jubail, Saudi Arabia
| | - Rinku Polachirakkal Varghese
- Laboratory of Integrative Genomics, Department of Integrative Biology, School of Bio Sciences and Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, India
| | - V Anu Preethi
- School of Computer Science and Engineering, Vellore Institute of Technology, Vellore, Tamil Nadu, India
| | - R Bithia
- Laboratory of Integrative Genomics, Department of Integrative Biology, School of Bio Sciences and Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, India
| | - C George Priya Doss
- Laboratory of Integrative Genomics, Department of Integrative Biology, School of Bio Sciences and Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, India.
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16
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Glucose-6-phosphatase catalytic subunit 2 negatively regulates glucose oxidation and insulin secretion in pancreatic β-cells. J Biol Chem 2022; 298:101729. [PMID: 35176280 PMCID: PMC8941207 DOI: 10.1016/j.jbc.2022.101729] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 02/11/2022] [Accepted: 02/12/2022] [Indexed: 12/11/2022] Open
Abstract
Elevated fasting blood glucose (FBG) is associated with increased risks of developing type 2 diabetes (T2D) and cardiovascular-associated mortality. G6PC2 is predominantly expressed in islets, encodes a glucose-6-phosphatase catalytic subunit that converts glucose-6-phosphate (G6P) to glucose, and has been linked with variations in FBG in genome-wide association studies. Deletion of G6pc2 in mice has been shown to lower FBG without affecting fasting plasma insulin levels in vivo. At 5 mM glucose, pancreatic islets from G6pc2 knockout (KO) mice exhibit no glucose cycling, increased glycolytic flux, and enhanced glucose-stimulated insulin secretion (GSIS). However, the broader effects of G6pc2 KO on β-cell metabolism and redox regulation are unknown. Here we used CRISPR/Cas9 gene editing and metabolic flux analysis in βTC3 cells, a murine pancreatic β-cell line, to examine the role of G6pc2 in regulating glycolytic and mitochondrial fluxes. We found that deletion of G6pc2 led to ∼60% increases in glycolytic and citric acid cycle (CAC) fluxes at both 5 and 11 mM glucose concentrations. Furthermore, intracellular insulin content and GSIS were enhanced by approximately two-fold, along with increased cytosolic redox potential and reductive carboxylation flux. Normalization of fluxes relative to net glucose uptake revealed upregulation in two NADPH-producing pathways in the CAC. These results demonstrate that G6pc2 regulates GSIS by modulating not only glycolysis but also, independently, citric acid cycle activity in β-cells. Overall, our findings implicate G6PC2 as a potential therapeutic target for enhancing insulin secretion and lowering FBG, which could benefit individuals with prediabetes, T2D, and obesity.
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17
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Overway EM, Bosma KJ, Claxton DP, Oeser JK, Singh K, Breidenbach LB, Mchaourab HS, Davis LK, O'Brien RM. Nonsynonymous single-nucleotide polymorphisms in the G6PC2 gene affect protein expression, enzyme activity, and fasting blood glucose. J Biol Chem 2022; 298:101534. [PMID: 34954144 PMCID: PMC8800118 DOI: 10.1016/j.jbc.2021.101534] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 12/16/2021] [Accepted: 12/17/2021] [Indexed: 12/30/2022] Open
Abstract
G6PC2 encodes a glucose-6-phosphatase (G6Pase) catalytic subunit that modulates the sensitivity of insulin secretion to glucose and thereby regulates fasting blood glucose (FBG). A common single-nucleotide polymorphism (SNP) in G6PC2, rs560887 is an important determinant of human FBG variability. This SNP has a subtle effect on G6PC2 RNA splicing, which raises the question as to whether nonsynonymous SNPs with a major impact on G6PC2 stability or enzyme activity might have a broader disease/metabolic impact. Previous attempts to characterize such SNPs were limited by the very low inherent G6Pase activity and expression of G6PC2 protein in islet-derived cell lines. In this study, we describe the use of a plasmid vector that confers high G6PC2 protein expression in islet cells, allowing for a functional analysis of 22 nonsynonymous G6PC2 SNPs, 19 of which alter amino acids that are conserved in mouse G6PC2 and the human and mouse variants of the related G6PC1 isoform. We show that 16 of these SNPs markedly impair G6PC2 protein expression (>50% decrease). These SNPs have variable effects on the stability of human and mouse G6PC1, despite the high sequence homology between these isoforms. Four of the remaining six SNPs impaired G6PC2 enzyme activity. Electronic health record-derived phenotype analyses showed an association between high-impact SNPs and FBG, but not other diseases/metabolites. While homozygous G6pc2 deletion in mice increases the risk of hypoglycemia, these human data reveal no evidence that the beneficial use of partial G6PC2 inhibitors to lower FBG would be associated with unintended negative consequences.
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Affiliation(s)
- Emily M Overway
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Karin J Bosma
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Derek P Claxton
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - James K Oeser
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Kritika Singh
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Lindsay B Breidenbach
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Hassane S Mchaourab
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Lea K Davis
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA; Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Richard M O'Brien
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA.
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18
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Cao M, Bu C, Zhang J, Ren Y, Zhou G, Chen C, Han G, Jiang SW, Wen J. Exosomal Circular RNA hsa_circ_0046060 of Umbilical Cord Mesenchymal Stromal Cell Ameliorates Glucose Metabolism and Insulin Resistance in Gestational Diabetes Mellitus via the miR-338-3p/G6PC2 Axis. Int J Endocrinol 2022; 2022:9218113. [PMID: 35726320 PMCID: PMC9206588 DOI: 10.1155/2022/9218113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 05/13/2022] [Accepted: 05/20/2022] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Impaired glucose metabolism and insulin sensitivity have been linked to the pathogenesis of gestational diabetes mellitus (GDM). Exosomes secreted by the umbilical cord mesenchymal stromal cells (UMSCs) and circular RNAs (circRNAs) derived from exosomes have been shown to be associated with the progression of GDM-related complications. METHODS UMSCs were isolated from umbilical cords and identified through flow cytometry. Exosomes were isolated from UMSCs and were then characterized. The expression levels of RNA of hsa_circ_0046060, mmu_circ_0002819, and miR-338-3p were determined by quantitative real-time polymerase chain reaction (RT-qPCR). The intracellular glucose intake and glycogen content were measured using a High Sensitivity Glucose Assay Kit and Glycogen Assay Kit, respectively. Bioinformatics analysis and luciferase reporter assay were used to validate interactions among hsa_circ_0046060, miR-338-3p, and G6PC2. The expression of insulin receptor substrate-1 (IRS-1) and its phosphorylated form, (p-IRS-1), as well as G6PC2, was determined through western blotting. RESULTS UMSCs and exosomes were successfully isolated and identified. The upregulation of hsa_circ_0046060 decreased the intracellular glucose content in L-02 cells (43.45 vs. 16.87 pM/mg, P=0.0002), whereas shRNA-mediated downregulation reversed this effect (16.87 vs. 33.16 pM/mg, P=0.0011). Mmu_circ_0002819 in mice aggravated dysregulated glucose metabolism (49.88 vs. 21.69 pM/mg, P=0.0031) and insulin sensitivity (0.20 vs. 0.11 mg/mL, P=0.03) in GDM mice, which was abrogated by the knockdown of mmu_circ_0002819. The results of luciferase reporter assay revealed that miR-338-3p and G6PC2 were the potential targets of has_circ_0046060. Western blotting results showed that the reduced activation of IRS-1 induced by GDM (1.25 vs. 0.54, P=0.0001) could be rescued by the administration of si-circ-G-UMSC-EXOs (0.54 vs. 1.17, P=0.0001). CONCLUSION Taken together, the inhibition of hsa_circ_0046060 expression in exosomes from GDM-derived UMSCs can alleviate GDM by reversing abnormal glucose metabolism and insulin resistance in vivo and in vitro.
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Affiliation(s)
- Minkai Cao
- Department of Gynecology and Obstetrics, The Second Hospital of Nanjing, Nanjing University of Chinese Medicine, Nanjing 210003, China
- Department of Obstetrics and Gynecology, The Affiliated Wuxi Matemity and Child Health Care Hospital of Nanjing Medical University, Wuxi 214002, Jiangsu, China
| | - Chaozhi Bu
- Center of Reproductive Medicine, State Key Laboratory of Reproductive Medicine, Research Institute for Reproductive Health and Genetic Diseases, The Affiliated Wuxi Matemity and Child Health Care Hospital of Nanjing Medical University, Wuxi 214002, Jiangsu, China
| | - Jingjing Zhang
- Department of Obstetrics and Gynecology, Qilu Hospital of Shandong University, Jinan 250012, Shandong, China
| | - Yongwei Ren
- Center of Reproductive Medicine, State Key Laboratory of Reproductive Medicine, Research Institute for Reproductive Health and Genetic Diseases, The Affiliated Wuxi Matemity and Child Health Care Hospital of Nanjing Medical University, Wuxi 214002, Jiangsu, China
| | - Guanlun Zhou
- Department of Gynecology and Obstetrics, The Second Hospital of Nanjing, Nanjing University of Chinese Medicine, Nanjing 210003, China
| | - Chao Chen
- Department of Gynecology and Obstetrics, The Second Hospital of Nanjing, Nanjing University of Chinese Medicine, Nanjing 210003, China
| | - Guorong Han
- Department of Gynecology and Obstetrics, The Second Hospital of Nanjing, Nanjing University of Chinese Medicine, Nanjing 210003, China
| | - Shi-Wen Jiang
- Center of Reproductive Medicine, State Key Laboratory of Reproductive Medicine, Research Institute for Reproductive Health and Genetic Diseases, The Affiliated Wuxi Matemity and Child Health Care Hospital of Nanjing Medical University, Wuxi 214002, Jiangsu, China
| | - Juan Wen
- Nanjing Maternity and Child Health Care Institute, Women's Hospital of Nanjing Medical University, Nanjing Maternity and Child Health Care Hospital, Nanjing 210004, China
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19
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Zusi C, Rinaldi E, Bonetti S, Boselli ML, Trabetti E, Malerba G, Bonora E, Bonadonna RC, Trombetta M. Haplotypes of the genes (GCK and G6PC2) underlying the glucose/glucose-6-phosphate cycle are associated with pancreatic beta cell glucose sensitivity in patients with newly diagnosed type 2 diabetes from the VNDS study (VNDS 11). J Endocrinol Invest 2021; 44:2567-2574. [PMID: 34128214 DOI: 10.1007/s40618-020-01483-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 12/07/2020] [Indexed: 10/21/2022]
Abstract
BACKGROUND Elevated fasting plasma glucose has been associated with increased risk for development of type 2 diabetes (T2D). The balance between glucokinase (GCK) and glucose-6-phosphate catalytic subunit 2 (G6PC2) activity are involved in glucose homeostasis through glycolytic flux, and subsequent insulin secretion. AIM In this study, we evaluated the association between the genetic variability of G6PC2 and GCK genes and T2D-related quantitative traits. METHODS In 794 drug-naïve, GADA-negative, newly diagnosed T2D patients (VNDS; NTC01526720) we performed: genotyping of 6 independent tag-SNPs within GCK gene and 5 tag-SNPs within G6PC2 gene; euglycaemic insulin clamp to assess insulin sensitivity; OGTT to estimate beta-cell function (derivative and proportional control; DC, PC) by mathematical modeling. Genetic association analysis has been conducted using Plink software. RESULTS Two SNPs within GCK gene (rs882019 and rs1303722) were associated to DC in opposite way (both p < 0.004). Two G6PC2 variants (rs13387347 and rs560887) were associated to both parameters of insulin secretion (DC and PC) and to fasting C-peptide levels (all p < 0.038). Moreover, subjects carrying the A allele of rs560887 showed higher values of 2h-plasma glucose (2hPG) (p = 0.033). Haplotype analysis revealed that GCK (AACAAA) haplotype was associated to decreased fasting C-peptide levels, whereas, the most frequent haplotype of G6PC2 (GGAAG) was associated with higher fasting C-peptide levels (p = 0.001), higher PC (β = 6.87, p = 0.022) and the lower 2hPG (p = 0.012). CONCLUSION Our findings confirmed the role of GCK and G6PC2 in regulating the pulsatility in insulin secretion thereby influencing insulin-signaling and leading to a gradual modulation in glucose levels in Italian patients with newly diagnosed T2D.
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Affiliation(s)
- C Zusi
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University and Hospital Trust of Verona, Piazzale Stefani 1, 37126, Verona, Italy
| | - E Rinaldi
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University and Hospital Trust of Verona, Piazzale Stefani 1, 37126, Verona, Italy
| | - S Bonetti
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University and Hospital Trust of Verona, Piazzale Stefani 1, 37126, Verona, Italy
| | - M L Boselli
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University and Hospital Trust of Verona, Piazzale Stefani 1, 37126, Verona, Italy
| | - E Trabetti
- Department of Neuroscience, Biomedicine and Movement Sciences, Section of Biology and Genetics, University of Verona, Verona, Italy
| | - G Malerba
- Department of Neuroscience, Biomedicine and Movement Sciences, Section of Biology and Genetics, University of Verona, Verona, Italy
| | - E Bonora
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University and Hospital Trust of Verona, Piazzale Stefani 1, 37126, Verona, Italy
| | - R C Bonadonna
- Department of Medicine and Surgery, University of Parma, Parma, Italy
- Division of Endocrinology and Metabolic Diseases, Azienda Ospedaliero-Universitaria di Parma, Parma, Italy
| | - M Trombetta
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University and Hospital Trust of Verona, Piazzale Stefani 1, 37126, Verona, Italy.
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20
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Schaschkow A, Pang L, Vandenbempt V, Elvira B, Litwak SA, Vekeriotaite B, Maillard E, Vermeersch M, Paula FMM, Pinget M, Perez-Morga D, Gough DJ, Gurzov EN. STAT3 Regulates Mitochondrial Gene Expression in Pancreatic β-Cells and Its Deficiency Induces Glucose Intolerance in Obesity. Diabetes 2021; 70:2026-2041. [PMID: 34183374 DOI: 10.2337/db20-1222] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 06/20/2021] [Indexed: 11/13/2022]
Abstract
Most obese and insulin-resistant individuals do not develop diabetes. This is the result of the capacity of β-cells to adapt and produce enough insulin to cover the needs of the organism. The underlying mechanism of β-cell adaptation in obesity, however, remains unclear. Previous studies have suggested a role for STAT3 in mediating β-cell development and human glucose homeostasis, but little is known about STAT3 in β-cells in obesity. We observed enhanced cytoplasmic expression of STAT3 in severely obese subjects with diabetes. To address the functional role of STAT3 in adult β-cells, we generated mice with tamoxifen-inducible partial or full deletion of STAT3 in β-cells and fed them a high-fat diet before analysis. Interestingly, β-cell heterozygous and homozygous STAT3-deficient mice showed glucose intolerance when fed a high-fat diet. Gene expression analysis with RNA sequencing showed that reduced expression of mitochondrial genes in STAT3 knocked down human EndoC-β1H cells, confirmed in FACS-purified β-cells from obese STAT3-deficient mice. Moreover, silencing of STAT3 impaired mitochondria activity in EndoC-β1H cells and human islets, suggesting a mechanism for STAT3-modulated β-cell function. Our study postulates STAT3 as a novel regulator of β-cell function in obesity.
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Affiliation(s)
- Anaïs Schaschkow
- Signal Transduction and Metabolism Laboratory, Laboratoire de Gastroentérologie Expérimental et Endotools, Université libre de Bruxelles, Brussels, Belgium
| | - Lokman Pang
- Department of Medicine, The University of Melbourne, Parkville, Australia
- St Vincent's Institute of Medical Research, Fitzroy, Australia
| | - Valerie Vandenbempt
- Signal Transduction and Metabolism Laboratory, Laboratoire de Gastroentérologie Expérimental et Endotools, Université libre de Bruxelles, Brussels, Belgium
| | - Bernat Elvira
- Signal Transduction and Metabolism Laboratory, Laboratoire de Gastroentérologie Expérimental et Endotools, Université libre de Bruxelles, Brussels, Belgium
| | - Sara A Litwak
- St Vincent's Institute of Medical Research, Fitzroy, Australia
| | - Beata Vekeriotaite
- Signal Transduction and Metabolism Laboratory, Laboratoire de Gastroentérologie Expérimental et Endotools, Université libre de Bruxelles, Brussels, Belgium
| | - Elisa Maillard
- Université de Strasbourg, Strasbourg, France
- Centre Européen d'Etude du Diabéte, Strasbourg, France
| | - Marjorie Vermeersch
- Center for Microscopy and Molecular Imaging, Université libre de Bruxelles, Brussels, Belgium
| | - Flavia M M Paula
- ULB-Center for Diabetes Research, Université libre de Bruxelles, Brussels, Belgium
| | - Michel Pinget
- Université de Strasbourg, Strasbourg, France
- Centre Européen d'Etude du Diabéte, Strasbourg, France
| | - David Perez-Morga
- Center for Microscopy and Molecular Imaging, Université libre de Bruxelles, Brussels, Belgium
| | - Daniel J Gough
- Centre for Cancer Research, Hudson Institute of Medical Research, Melbourne, Australia
- Department of Science and Translational Medicine, Monash University, Melbourne, Australia
| | - Esteban N Gurzov
- Signal Transduction and Metabolism Laboratory, Laboratoire de Gastroentérologie Expérimental et Endotools, Université libre de Bruxelles, Brussels, Belgium
- Department of Medicine, The University of Melbourne, Parkville, Australia
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21
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Chung RH, Chiu YF, Wang WC, Hwu CM, Hung YJ, Lee IT, Chuang LM, Quertermous T, Rotter JI, Chen YDI, Chang IS, Hsiung CA. Multi-omics analysis identifies CpGs near G6PC2 mediating the effects of genetic variants on fasting glucose. Diabetologia 2021; 64:1613-1625. [PMID: 33842983 DOI: 10.1007/s00125-021-05449-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 02/08/2021] [Indexed: 10/21/2022]
Abstract
AIMS/HYPOTHESIS An elevated fasting glucose level in non-diabetic individuals is a key predictor of type 2 diabetes. Genome-wide association studies (GWAS) have identified hundreds of SNPs for fasting glucose but most of their functional roles in influencing the trait are unclear. This study aimed to identify the mediation effects of DNA methylation between SNPs identified as significant from GWAS and fasting glucose using Mendelian randomisation (MR) analyses. METHODS We first performed GWAS analyses for three cohorts (Taiwan Biobank with 18,122 individuals, the Healthy Aging Longitudinal Study in Taiwan with 1989 individuals and the Stanford Asia-Pacific Program for Hypertension and Insulin Resistance with 416 individuals) with individuals of Han Chinese ancestry in Taiwan, followed by a meta-analysis for combining the three GWAS analysis results to identify significant and independent SNPs for fasting glucose. We determined whether these SNPs were methylation quantitative trait loci (meQTLs) by testing their associations with DNA methylation levels at nearby CpG sites using a subsample of 1775 individuals from the Taiwan Biobank. The MR analysis was performed to identify DNA methylation with causal effects on fasting glucose using meQTLs as instrumental variables based on the 1775 individuals. We also used a two-sample MR strategy to perform replication analysis for CpG sites with significant MR effects based on literature data. RESULTS Our meta-analysis identified 18 significant (p < 5 × 10-8) and independent SNPs for fasting glucose. Interestingly, all 18 SNPs were meQTLs. The MR analysis identified seven CpGs near the G6PC2 gene that mediated the effects of a significant SNP (rs2232326) in the gene on fasting glucose. The MR effects for two CpGs were replicated using summary data based on the European population, using an exonic SNP rs2232328 in G6PC2 as the instrument. CONCLUSIONS/INTERPRETATION Our analysis results suggest that rs2232326 and rs2232328 in G6PC2 may affect DNA methylation at CpGs near the gene and that the methylation may have downstream effects on fasting glucose. Therefore, SNPs in G6PC2 and CpGs near G6PC2 may reside along the pathway that influences fasting glucose levels. This is the first study to report CpGs near G6PC2, an important gene for regulating insulin secretion, mediating the effects of GWAS-significant SNPs on fasting glucose.
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Affiliation(s)
- Ren-Hua Chung
- Division of Biostatistics and Bioinformatics, Institute of Population Health Sciences, National Health Research Institutes, Zhunan, Taiwan.
| | - Yen-Feng Chiu
- Division of Biostatistics and Bioinformatics, Institute of Population Health Sciences, National Health Research Institutes, Zhunan, Taiwan
| | - Wen-Chang Wang
- The Ph.D. Program for Translational Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan
| | - Chii-Min Hwu
- Section of Endocrinology and Metabolism, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
- School of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Yi-Jen Hung
- Division of Endocrine and Metabolism, Tri-Service General Hospital, Taipei, Taiwan
- Institute of Preventive Medicine, National Defense Medical Center, Taipei, Taiwan
| | - I-Te Lee
- School of Medicine, National Yang-Ming University, Taipei, Taiwan
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Taichung Veterans General Hospital, Taichung, Taiwan
- School of Medicine, Chung Shan Medical University, Taichung, Taiwan
| | - Lee-Ming Chuang
- Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
- Institutes of Molecular Medicine, Collage of Medicine, National Taiwan University, Taipei, Taiwan
| | - Thomas Quertermous
- Division of Cardiovascular Medicine and Stanford Cardiovascular Institute, Falk Cardiovascular Research Center, Stanford University, Stanford, CA, USA
| | - Jerome I Rotter
- Institute for Translational Genomics and Population Sciences, the Lundquist Institute, Harbor-UCLA Medical Center, Torrance, CA, USA
- Department of Pediatrics, Harbor-UCLA Medical Center, Torrance, CA, USA
| | - Yii-Der I Chen
- Institute for Translational Genomics and Population Sciences, the Lundquist Institute, Harbor-UCLA Medical Center, Torrance, CA, USA
- Department of Pediatrics, Harbor-UCLA Medical Center, Torrance, CA, USA
| | - I-Shou Chang
- National Institute of Cancer Research, National Health Research Institutes, Zhunan, Taiwan
| | - Chao A Hsiung
- Division of Biostatistics and Bioinformatics, Institute of Population Health Sciences, National Health Research Institutes, Zhunan, Taiwan.
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22
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Lubkemann A, Carpenter H, O'Brien R, Baldwin S, Lister R. Cardiac Morphology and Collagen Deposition in A Glucose-6-Phosphatase Catalytic Subunit 3 (G6PC3) Knockout Mouse model. ACTA ACUST UNITED AC 2021. [PMID: 34263175 DOI: 10.33425/2639-944x.1188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Background Glucose-6-phosphatase-- β (3), one of multiple isoforms of glucose-6-phosphatase, catalyzes the final step in gluconeogenesis. It is known that mutated G6P3 is associated with severe neutropenia in addition to congenital heart defects, but little is known about the histological changes in cardiac tissue as a result of mutated or deleted G6PC34. Objectives We sought to further characterize the histological alterations caused by deleted G6PC3 and determine the role of collagen deposition, myocyte proliferation and apoptosis in these changes. Methods Cardiac tissue from G6PC3 knockout mice and WT mice were harvested, imbedded and stained for markers of collagen (Trichrome), proliferation (KI-67), apoptosis (caspase 3) and hematopoietic stem cells (CD34). Slides were digitally uploaded, and Leica stain quantification was calculated. Results We demonstrated that in G6PC3 knock out adult mice have significant differences in heart morphology including decreased left ventricular collagen, decreased cellular proliferation and increased apoptosis histologically. Conclusions As compared to wild type, the hearts of G6PC3 knockout mice demonstrated significantly decreased collagen globally, a crucial component for adequate strength and contractility of myocardial tissue. More investigation should be done to further explore the functional effects of such alterations via echocardiograms.
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Affiliation(s)
- Austin Lubkemann
- Vanderbilt University Medical Center, Nashville, Tennessee.,UNC Chapel Hill, North Carolina
| | - Heidi Carpenter
- Vanderbilt University Medical Center, Nashville, Tennessee.,UNC Chapel Hill, North Carolina
| | | | - Scott Baldwin
- Vanderbilt University Medical Center, Nashville, Tennessee
| | - Rolanda Lister
- Vanderbilt University Medical Center, Nashville, Tennessee
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23
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Nasteska D, Fine NHF, Ashford FB, Cuozzo F, Viloria K, Smith G, Dahir A, Dawson PWJ, Lai YC, Bastidas-Ponce A, Bakhti M, Rutter GA, Fiancette R, Nano R, Piemonti L, Lickert H, Zhou Q, Akerman I, Hodson DJ. PDX1 LOW MAFA LOW β-cells contribute to islet function and insulin release. Nat Commun 2021; 12:674. [PMID: 33514698 PMCID: PMC7846747 DOI: 10.1038/s41467-020-20632-z] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 12/01/2020] [Indexed: 12/25/2022] Open
Abstract
Transcriptionally mature and immature β-cells co-exist within the adult islet. How such diversity contributes to insulin release remains poorly understood. Here we show that subtle differences in β-cell maturity, defined using PDX1 and MAFA expression, contribute to islet operation. Functional mapping of rodent and human islets containing proportionally more PDX1HIGH and MAFAHIGH β-cells reveals defects in metabolism, ionic fluxes and insulin secretion. At the transcriptomic level, the presence of increased numbers of PDX1HIGH and MAFAHIGH β-cells leads to dysregulation of gene pathways involved in metabolic processes. Using a chemogenetic disruption strategy, differences in PDX1 and MAFA expression are shown to depend on islet Ca2+ signaling patterns. During metabolic stress, islet function can be restored by redressing the balance between PDX1 and MAFA levels across the β-cell population. Thus, preserving heterogeneity in PDX1 and MAFA expression, and more widely in β-cell maturity, might be important for the maintenance of islet function.
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Affiliation(s)
- Daniela Nasteska
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham, UK.,Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK.,Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK
| | - Nicholas H F Fine
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham, UK.,Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK.,Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK
| | - Fiona B Ashford
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham, UK.,Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK.,Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK
| | - Federica Cuozzo
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham, UK.,Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK.,Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK
| | - Katrina Viloria
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham, UK.,Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK.,Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK
| | - Gabrielle Smith
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham, UK.,Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK
| | - Aisha Dahir
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham, UK.,Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK
| | - Peter W J Dawson
- School of Sport, Exercise and Rehabilitation Science, University of Birmingham, Edgbaston, UK.,MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research, University of Birmingham, Edgbaston, UK
| | - Yu-Chiang Lai
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham, UK.,School of Sport, Exercise and Rehabilitation Science, University of Birmingham, Edgbaston, UK.,MRC-Versus Arthritis Centre for Musculoskeletal Ageing Research, University of Birmingham, Edgbaston, UK
| | - Aimée Bastidas-Ponce
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, D-85764, Neuherberg, Germany.,German Center for Diabetes Research (DZD), D-85764, Neuherberg, Germany.,Institute of Stem Cell Research, Helmholtz Zentrum München, D-85764, Neuherberg, Germany.,Technical University of Munich, School of Medicine, Munich, Germany
| | - Mostafa Bakhti
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, D-85764, Neuherberg, Germany.,German Center for Diabetes Research (DZD), D-85764, Neuherberg, Germany.,Institute of Stem Cell Research, Helmholtz Zentrum München, D-85764, Neuherberg, Germany
| | - Guy A Rutter
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology, and Metabolism, Department of Metabolism, Reproduction, and Digestion, Imperial College London, London, UK.,Lee Kong Chian School of Medicine, Nanyang Technological University, Nanyang, Singapore
| | - Remi Fiancette
- Institute of Immunology & Immunotherapy, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - Rita Nano
- San Raffaele Diabetes Research Institute, IRCCS Ospedale, San Raffaele, Italy.,Vita-Salute San Raffaele University, Milan, Italy
| | - Lorenzo Piemonti
- San Raffaele Diabetes Research Institute, IRCCS Ospedale, San Raffaele, Italy.,Vita-Salute San Raffaele University, Milan, Italy
| | - Heiko Lickert
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, D-85764, Neuherberg, Germany.,German Center for Diabetes Research (DZD), D-85764, Neuherberg, Germany.,Institute of Stem Cell Research, Helmholtz Zentrum München, D-85764, Neuherberg, Germany.,Technical University of Munich, School of Medicine, Munich, Germany
| | - Qiao Zhou
- Division of Regenerative Medicine, Department of Medicine, Weill Cornell Medical College, New York, NY, USA
| | - Ildem Akerman
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham, UK.,Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK
| | - David J Hodson
- Institute of Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham, UK. .,Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, Midlands, UK. .,Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK.
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24
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Avrahami D, Wang YJ, Schug J, Feleke E, Gao L, Liu C, Naji A, Glaser B, Kaestner KH. Single-cell transcriptomics of human islet ontogeny defines the molecular basis of β-cell dedifferentiation in T2D. Mol Metab 2020; 42:101057. [PMID: 32739450 PMCID: PMC7471622 DOI: 10.1016/j.molmet.2020.101057] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Revised: 07/20/2020] [Accepted: 07/27/2020] [Indexed: 01/03/2023] Open
Abstract
OBJECTIVE Dedifferentiation of pancreatic β-cells may reduce islet function in type 2 diabetes (T2D). However, the prevalence, plasticity and functional consequences of this cellular state remain unknown. METHODS We employed single-cell RNAseq to detail the maturation program of α- and β-cells during human ontogeny. We also compared islets from non-diabetic and T2D individuals. RESULTS Both α- and β-cells mature in part by repressing non-endocrine genes; however, α-cells retain hallmarks of an immature state, while β-cells attain a full β-cell specific gene expression program. In islets from T2D donors, both α- and β-cells have a less mature expression profile, de-repressing the juvenile genetic program and exocrine genes and increasing expression of exocytosis, inflammation and stress response signalling pathways. These changes are consistent with the increased proportion of β-cells displaying suboptimal function observed in T2D islets. CONCLUSIONS These findings provide new insights into the molecular program underlying islet cell maturation during human ontogeny and the loss of transcriptomic maturity that occurs in islets of type 2 diabetics.
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Affiliation(s)
- Dana Avrahami
- Endocrinology and Metabolism Department, Hadassah-Hebrew University Medical Centre, Jerusalem, Israel
| | - Yue J Wang
- Department of Genetics and Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Jonathan Schug
- Department of Genetics and Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Eseye Feleke
- Endocrinology and Metabolism Department, Hadassah-Hebrew University Medical Centre, Jerusalem, Israel
| | - Long Gao
- Department of Genetics and Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Chengyang Liu
- Department of Surgery and Institute for Diabetes, Obesity and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ali Naji
- Department of Surgery and Institute for Diabetes, Obesity and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Benjamin Glaser
- Endocrinology and Metabolism Department, Hadassah-Hebrew University Medical Centre, Jerusalem, Israel.
| | - Klaus H Kaestner
- Department of Genetics and Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
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25
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Si Z, Guan X, Teng X, Peng X, Wan Z, Li Q, Chen G, Tan J, Li J. Identification of CYP46A1 as a new regulator of lipid metabolism through CRISPR-based whole-genome screening. FASEB J 2020; 34:13776-13791. [PMID: 32816363 DOI: 10.1096/fj.202001067r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 07/23/2020] [Accepted: 08/03/2020] [Indexed: 12/30/2022]
Abstract
Abnormal lipid droplet (LD) metabolism causes a variety of disorders, especially to nonalcoholic fatty liver disease (NAFLD). But the mechanism of abnormal aggregation of LD is still not fully elucidated. Here, Genome-wide CRISPR-Cas9 knockout (GeCKO) screening was employed to identify candidate genes regulating LD metabolism in L02 cell. We analyzed simultaneously the transcriptomics of liver tissues of NAFLD to find potential genes involved in pathogenesis of NAFLD. After integration these data, we found that the expression of 43 candidate genes from the GeCKO screening was also decreased in tissues of NAFLD patients. Many of these 43 overlapping genes have been reported to play an important role in the formation of LD. Subsequently, we focused on CYP46A1, one of 43 candidate genes and mitochondria-related genes. We confirmed that the protein expression of CYP46A1 is deceased in tissues of NAFLD patients. Downregulation or overexpression of CYP46A1 affected LD accumulation in vitro. Deficiency of CYP46A1 impaired mitochondrial morphology and function, which may be responsible for the accumulation of LD. In summary, this study explored regulatory factors of LD accumulation at the whole-genome level, and demonstrated that CYP46A1 regulated LD formation involving in NAFLD pathogenesis. It provides new clues for studying the molecular mechanisms of diseases related to abnormal lipid metabolism.
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Affiliation(s)
- Zhongzhou Si
- Center for Organ Transplantation, Second Xiangya Hospital, Central South University, Changsha, P.R. China
| | - Xinjie Guan
- Center for Medical Genetics, School of Life Science, Central South University, Changsha, P.R. China
| | | | - Xiaoxia Peng
- Center for Medical Genetics, School of Life Science, Central South University, Changsha, P.R. China
| | - Zhengqin Wan
- Center for Medical Genetics, School of Life Science, Central South University, Changsha, P.R. China
| | - Qiang Li
- Center for Organ Transplantation, Second Xiangya Hospital, Central South University, Changsha, P.R. China
| | - Guangshun Chen
- Center for Organ Transplantation, Second Xiangya Hospital, Central South University, Changsha, P.R. China
| | - Jieqiong Tan
- Center for Medical Genetics, School of Life Science, Central South University, Changsha, P.R. China
| | - Jiequn Li
- Center for Organ Transplantation, Second Xiangya Hospital, Central South University, Changsha, P.R. China
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26
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Gupta MK, Vadde R. Divergent evolution and purifying selection of the Type 2 diabetes gene sequences in Drosophila: a phylogenomic study. Genetica 2020; 148:269-282. [PMID: 32804315 DOI: 10.1007/s10709-020-00101-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2019] [Accepted: 08/12/2020] [Indexed: 11/24/2022]
Abstract
The recently developed phylogenomic approach provides a unique way to identify disease risk or protective allele in any organism. While risk alleles evolve mostly under purifying selection, protective alleles are evolving either under balancing or positive selection. Owing to insufficient information, authors employed the phylogenomic approach to detect the nature of selection acting on type 2 diabetes (T2D) genes in Drosophila genus using various models of CODEML utility of PAML. The obtained result revealed that T2D gene sequences are evolving under purifying selection. However, only a few sites in membrane proteins encoded via CG8051, ZnT35C, and kar, are significantly evolving under positive selection under specific scenarios, which might be because of positive or adaptive evolution in response to changing niche, diet or other factors. In the near future, this information will be highly useful in the field of evolutionary medicine and the drug discovery process.
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Affiliation(s)
- Manoj Kumar Gupta
- Department of Biotechnology & Bioinformatics, Yogi Vemana University, Kadapa, Andhra Pradesh, 516005, India
| | - Ramakrishna Vadde
- Department of Biotechnology & Bioinformatics, Yogi Vemana University, Kadapa, Andhra Pradesh, 516005, India.
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27
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Mosleh E, Ou K, Haemmerle MW, Tembo T, Yuhas A, Carboneau BA, Townsend SE, Bosma KJ, Gannon M, O’Brien RM, Stoffers DA, Golson ML. Ins1-Cre and Ins1-CreER Gene Replacement Alleles Are Susceptible To Silencing By DNA Hypermethylation. Endocrinology 2020; 161:5817889. [PMID: 32267917 PMCID: PMC7354059 DOI: 10.1210/endocr/bqaa054] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 04/07/2020] [Indexed: 12/14/2022]
Abstract
Targeted gene ablation studies of the endocrine pancreas have long suffered from suboptimal Cre deleter strains. In many cases, Cre lines purportedly specific for beta cells also displayed expression in other islet endocrine cells or in a subset of neurons in the brain. Several pancreas and endocrine Cre lines have experienced silencing or mosaicism over time. In addition, many Cre transgenic constructs were designed to include the hGH mini-gene, which by itself increases beta-cell replication and decreases beta-cell function. More recently, driver lines with Cre or CreER inserted into the Ins1 locus were generated, with the intent of producing β cell-specific Cre lines with faithful recapitulation of insulin expression. These lines were bred in multiple labs to several different mouse lines harboring various lox alleles. In our hands, the ability of the Ins1-Cre and Ins1-CreER lines to delete target genes varied from that originally reported, with both alleles displaying low levels of expression, increased levels of methylation compared to the wild-type allele, and ultimately inefficient or absent target deletion. Thus, caution is warranted in the interpretation of results obtained with these genetic tools, and Cre expression and activity should be monitored regularly when using these lines.
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Affiliation(s)
- Elham Mosleh
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
- Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Kristy Ou
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
- Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Matthew W Haemmerle
- Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Teguru Tembo
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
- Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Andrew Yuhas
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
- Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Bethany A Carboneau
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Shannon E Townsend
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Karin J Bosma
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Maureen Gannon
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
- United States Department of Veteran Affairs, Nashville, Tennessee
| | - Richard M O’Brien
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee
| | - Doris A Stoffers
- Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Maria L Golson
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
- Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
- Department of Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland
- Correspondence: Maria L. Golson, PhD, 5501 Hopkins Bayview Circle, Baltimore, MD 21224. E-mail:
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28
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Syring KE, Bosma KJ, Goleva SB, Singh K, Oeser JK, Lopez CA, Skaar EP, McGuinness OP, Davis LK, Powell DR, O’Brien RM. Potential positive and negative consequences of ZnT8 inhibition. J Endocrinol 2020; 246:189-205. [PMID: 32485672 PMCID: PMC7351606 DOI: 10.1530/joe-20-0138] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 06/02/2020] [Indexed: 12/31/2022]
Abstract
SLC30A8 encodes the zinc transporter ZnT8. SLC30A8 haploinsufficiency protects against type 2 diabetes (T2D), suggesting that ZnT8 inhibitors may prevent T2D. We show here that, while adult chow fed Slc30a8 haploinsufficient and knockout (KO) mice have normal glucose tolerance, they are protected against diet-induced obesity (DIO), resulting in improved glucose tolerance. We hypothesize that this protection against DIO may represent one mechanism whereby SLC30A8 haploinsufficiency protects against T2D in humans and that, while SLC30A8 is predominantly expressed in pancreatic islet beta cells, this may involve a role for ZnT8 in extra-pancreatic tissues. Consistent with this latter concept we show in humans, using electronic health record-derived phenotype analyses, that the 'C' allele of the non-synonymous rs13266634 SNP, which confers a gain of ZnT8 function, is associated not only with increased T2D risk and blood glucose, but also with increased risk for hemolytic anemia and decreased mean corpuscular hemoglobin (MCH). In Slc30a8 KO mice, MCH was unchanged but reticulocytes, platelets and lymphocytes were elevated. Both young and adult Slc30a8 KO mice exhibit a delayed rise in insulin after glucose injection, but only the former exhibit increased basal insulin clearance and impaired glucose tolerance. Young Slc30a8 KO mice also exhibit elevated pancreatic G6pc2 gene expression, potentially mediated by decreased islet zinc levels. These data indicate that the absence of ZnT8 results in a transient impairment in some aspects of metabolism during development. These observations in humans and mice suggest the potential for negative effects associated with T2D prevention using ZnT8 inhibitors.
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Affiliation(s)
- Kristen E. Syring
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine
| | - Karin J. Bosma
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine
| | - Slavina B. Goleva
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232
| | - Kritika Singh
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232
| | - James K. Oeser
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine
| | - Christopher A. Lopez
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232
| | - Eric P. Skaar
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232
| | - Owen P. McGuinness
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine
| | - Lea K. Davis
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232
| | - David R. Powell
- Lexicon Pharmaceuticals Incorporated, 8800 Technology Forest Place, The Woodlands, Texas 77381
| | - Richard M. O’Brien
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine
- To whom correspondence should be addressed: Department of Molecular Physiology and Biophysics, 8415 MRB IV, 2213 Garland Ave Vanderbilt University Medical School, Nashville, TN 37232-0615,
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Bosma KJ, Rahim M, Oeser JK, McGuinness OP, Young JD, O'Brien RM. G6PC2 confers protection against hypoglycemia upon ketogenic diet feeding and prolonged fasting. Mol Metab 2020; 41:101043. [PMID: 32569842 PMCID: PMC7369601 DOI: 10.1016/j.molmet.2020.101043] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 05/26/2020] [Accepted: 06/16/2020] [Indexed: 12/14/2022] Open
Abstract
Objective G6PC2 is predominantly expressed in pancreatic islet beta cells. G6PC2 hydrolyzes glucose-6-phosphate to glucose and inorganic phosphate, thereby creating a futile substrate cycle that opposes the action of glucokinase. This substrate cycle determines the sensitivity of glucose-stimulated insulin secretion to glucose and hence regulates fasting blood glucose (FBG) but not fasting plasma insulin (FPI) levels. Our objective was to explore the physiological benefit this cycle confers. Methods We investigated the response of wild type (WT) and G6pc2 knockout (KO) mice to changes in nutrition. Results Pancreatic G6pc2 expression was little changed by ketogenic diet feeding but was inhibited by 24 hr fasting and strongly induced by high fat feeding. When challenged with either a ketogenic diet or 24 hr fasting, blood glucose fell to 70 mg/dl or less in G6pc2 KO but not WT mice, suggesting that G6PC2 may have evolved, in part, to prevent hypoglycemia. Prolonged ketogenic diet feeding reduced the effect of G6pc2 deletion on FBG. The hyperglycemia associated with high fat feeding was partially blunted in G6pc2 KO mice, suggesting that under these conditions the presence of G6PC2 is detrimental. As expected, FPI changed but did not differ between WT and KO mice in response to fasting, ketogenic and high fat feeding. Conclusions Since elevated FBG levels are associated with increased risk for cardiovascular-associated mortality (CAM), these studies suggest that, while G6PC2 inhibitors would be useful for lowering FBG and the risk of CAM, partial inhibition will be important to avoid the risk of hypoglycemia. G6pc2 deletion lowers fasting blood glucose (FBG) in chow and high fat fed mice. Elevated FBG increases the risk of cardiovascular-associated mortality (CAM). G6pc2 deletion results in hypoglycemia in mice on a ketogenic diet. G6pc2 deletion results in hypoglycemia in mice following prolonged fasting. G6PC2 inhibitors may prevent CAM but increase risk of hypoglycemia.
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Affiliation(s)
- Karin J Bosma
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Mohsin Rahim
- Department of Chemical and Biomolecular Engineering, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - James K Oeser
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Owen P McGuinness
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Jamey D Young
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Department of Chemical and Biomolecular Engineering, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Richard M O'Brien
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
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30
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Bosma KJ, Rahim M, Singh K, Goleva SB, Wall ML, Xia J, Syring KE, Oeser JK, Poffenberger G, McGuinness OP, Means AL, Powers AC, Li WH, Davis LK, Young JD, O’Brien RM. Pancreatic islet beta cell-specific deletion of G6pc2 reduces fasting blood glucose. J Mol Endocrinol 2020; 64:235-248. [PMID: 32213654 PMCID: PMC7331801 DOI: 10.1530/jme-20-0031] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 03/13/2020] [Indexed: 12/25/2022]
Abstract
The G6PC1, G6PC2 and G6PC3 genes encode distinct glucose-6-phosphatase catalytic subunit (G6PC) isoforms. In mice, germline deletion of G6pc2 lowers fasting blood glucose (FBG) without affecting fasting plasma insulin (FPI) while, in isolated islets, glucose-6-phosphatase activity and glucose cycling are abolished and glucose-stimulated insulin secretion (GSIS) is enhanced at submaximal but not high glucose. These observations are all consistent with a model in which G6PC2 regulates the sensitivity of GSIS to glucose by opposing the action of glucokinase. G6PC2 is highly expressed in human and mouse islet beta cells however, various studies have shown trace G6PC2 expression in multiple tissues raising the possibility that G6PC2 also affects FBG through non-islet cell actions. Using real-time PCR we show here that expression of G6pc1 and/or G6pc3 are much greater than G6pc2 in peripheral tissues, whereas G6pc2 expression is much higher than G6pc3 in both pancreas and islets with G6pc1 expression not detected. In adult mice, beta cell-specific deletion of G6pc2 was sufficient to reduce FBG without changing FPI. In addition, electronic health record-derived phenotype analyses showed no association between G6PC2 expression and phenotypes clearly unrelated to islet function in humans. Finally, we show that germline G6pc2 deletion enhances glycolysis in mouse islets and that glucose cycling can also be detected in human islets. These observations are all consistent with a mechanism by which G6PC2 action in islets is sufficient to regulate the sensitivity of GSIS to glucose and hence influence FBG without affecting FPI.
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Affiliation(s)
- Karin J. Bosma
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Mohsin Rahim
- Department of Chemical and Biomolecular Engineering, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Kritika Singh
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Slavina B. Goleva
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Martha L. Wall
- Department of Chemical and Biomolecular Engineering, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Jing Xia
- Departments of Cell Biology and of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390-9039
| | - Kristen E. Syring
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - James K. Oeser
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Greg Poffenberger
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Owen P. McGuinness
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Anna L. Means
- Department of Surgery, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Alvin C. Powers
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232
- VA Tennessee Valley Healthcare System, Nashville, TN 37232
| | - Wen-hong Li
- Departments of Cell Biology and of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390-9039
| | - Lea K. Davis
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Jamey D. Young
- Department of Chemical and Biomolecular Engineering, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Richard M. O’Brien
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232
- To whom correspondence should be addressed: Department of Molecular Physiology and Biophysics, 8415 MRB IV, 2213 Garland Ave, Vanderbilt University Medical School, Nashville, TN 37232-0615,
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31
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Wang X, Jia J, Huang T. Shared genetic architecture and casual relationship between leptin levels and type 2 diabetes: large-scale cross-trait meta-analysis and Mendelian randomization analysis. BMJ Open Diabetes Res Care 2020; 8:8/1/e001140. [PMID: 32341051 PMCID: PMC7202746 DOI: 10.1136/bmjdrc-2019-001140] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 03/03/2020] [Accepted: 03/12/2020] [Indexed: 02/06/2023] Open
Abstract
OBJECTIVE We aimed to estimate genetic correlation, identify shared loci and test causality between leptin levels and type 2 diabetes (T2D). RESEARCH DESIGN AND METHODS Our study consists of three parts. First, we calculated the genetic correlation of leptin levels and T2D or glycemic traits by using linkage disequilibrium score regression analysis. Second, we conducted a large-scale genome-wide cross-trait meta-analysis using cross-phenotype association to identify shared loci between trait pairs that showed significant genetic correlations in the first part. In the end, we carried out a bidirectional MR analysis to find out whether there is a causal relationship between leptin levels and T2D or glycemic traits. RESULTS We found positive genetic correlations between leptin levels and T2D (Rg=0.3165, p=0.0227), fasting insulin (FI) (Rg=0.517, p=0.0076), homeostasis model assessment-insulin resistance (HOMA-IR) (Rg=0.4785, p=0.0196), as well as surrogate estimates of β-cell function (HOMA-β) (Rg=0.4456, p=0.0214). We identified 12 shared loci between leptin levels and T2D, 1 locus between leptin levels and FI, 1 locus between leptin levels and HOMA-IR, and 1 locus between leptin levels and HOMA-β. We newly identified eight loci that did not achieve genome-wide significance in trait-specific genome-wide association studies. These shared genes were enriched in pancreas, thyroid gland, skeletal muscle, placenta, liver and cerebral cortex. In addition, we found that 1-SD increase in HOMA-IR was causally associated with a 0.329 ng/mL increase in leptin levels (β=0.329, p=0.001). CONCLUSIONS Our results have shown the shared genetic architecture between leptin levels and T2D and found causality of HOMA-IR on leptin levels, shedding light on the molecular mechanisms underlying the association between leptin levels and T2D.
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Affiliation(s)
- Xinpei Wang
- Department of Biostatistics, School of Public Health, Peking University, Beijing, China
| | - Jinzhu Jia
- Department of Biostatistics, School of Public Health, Peking University, Beijing, China
- Center for Statistical Science, Peking University, Beijing, China
| | - Tao Huang
- Department of Epidemiology & Biostatistics, School of Public Health, Peking University, Beijing, China
- Department of Global Health, School of Public Health, Peking University, Beijing, China
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32
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Westermeier F, Holyoak T, Asenjo JL, Gatica R, Nualart F, Burbulis I, Bertinat R. Gluconeogenic Enzymes in β-Cells: Pharmacological Targets for Improving Insulin Secretion. Trends Endocrinol Metab 2019; 30:520-531. [PMID: 31213347 DOI: 10.1016/j.tem.2019.05.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 05/14/2019] [Accepted: 05/16/2019] [Indexed: 02/06/2023]
Abstract
Pancreatic β-cells express the gluconeogenic enzymes glucose 6-phosphatase (G6Pase), fructose 1,6-bisphosphatase (FBP), and phosphoenolpyruvate (PEP) carboxykinase (PCK), which modulate glucose-stimulated insulin secretion (GSIS) through their ability to reverse otherwise irreversible glycolytic steps. Here, we review current knowledge about the expression and regulation of these enzymes in the context of manipulating them to improve insulin secretion in diabetics. Because the regulation of gluconeogenic enzymes in β-cells is so poorly understood, we propose novel research avenues to study these enzymes as modulators of insulin secretion and β-cell dysfunction, with especial attention to FBP, which constitutes an attractive target with an inhibitor under clinical evaluation at present.
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Affiliation(s)
- Francisco Westermeier
- FH JOANNEUM Gesellschaft mbH University of Applied Sciences, Institute of Biomedical Science, Eggenberger Allee 13, 8020 Graz, Austria
| | - Todd Holyoak
- Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - Joel L Asenjo
- Instituto de Bioquímica y Microbiología, Facultad de Ciencias, Universidad Austral de Chile, Independencia 631, 5110566 Valdivia, Chile
| | - Rodrigo Gatica
- Escuela de Veterinaria, Facultad de Ciencias, Universidad Mayor, La Pirámide 5750, 8580745 Santiago, Chile
| | - Francisco Nualart
- Centro de Microscopía Avanzada, CMA BIO, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160 C, 4030000 Concepción, Chile
| | - Ian Burbulis
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Virginia, Jordan Hall Room 6022, 1340 Jefferson Park Avenue, Charlottesville, VA 22908, USA; Escuela de Medicina, Universidad San Sebastián, Sede Patagonia, Lago Panguipulli 1390, 5501842 Puerto Montt, Chile
| | - Romina Bertinat
- Centro de Microscopía Avanzada, CMA BIO, Facultad de Ciencias Biológicas, Universidad de Concepción, Casilla 160 C, 4030000 Concepción, Chile.
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Miyamoto T, Amrein H. Neuronal Gluconeogenesis Regulates Systemic Glucose Homeostasis in Drosophila melanogaster. Curr Biol 2019; 29:1263-1272.e5. [DOI: 10.1016/j.cub.2019.02.053] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 01/21/2019] [Accepted: 02/25/2019] [Indexed: 11/25/2022]
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34
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van Gurp L, Muraro MJ, Dielen T, Seneby L, Dharmadhikari G, Gradwohl G, van Oudenaarden A, de Koning EJP. A transcriptomic roadmap to alpha- and beta cell differentiation in the embryonic pancreas. Development 2019; 146:dev.173716. [DOI: 10.1242/dev.173716] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 05/24/2019] [Indexed: 12/13/2022]
Abstract
During pancreatic development, endocrine cells appear from the pancreatic epithelium when Neurog3 positive cells delaminate and differentiate into alpha, beta, gamma and delta cells. The mechanisms involved in this process are still incompletely understood. We characterized the temporal, lineage-specific developmental programs during pancreatic development by sequencing the transcriptome of thousands of individual pancreatic cells from embryonic day E12.5 to E18.5 in mice, and identified all known cell types that are present in the embryonic pancreas, but focused specifically on alpha and beta cell differentiation by enrichment of a MIP-GFP reporter. We characterized transcriptomic heterogeneity in the tip domain based on proliferation, and characterized two endocrine precursor clusters marked by expression of Neurog3 and Fev. Pseudotime analysis revealed specific branches for developing alpha- and beta cells, which allowed identification of specific gene regulation patterns. These include some known and many previously unreported genes that appear to define pancreatic cell fate transitions. This resource allows dynamic profiling of embryonic pancreas development at single cell resolution and reveals novel gene signatures during pancreatic differentiation into alpha and beta cells.
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Affiliation(s)
- Léon van Gurp
- Hubrecht Institute\KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584CT Utrecht, the Netherlands
| | - Mauro J. Muraro
- Hubrecht Institute\KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584CT Utrecht, the Netherlands
- Single Cell Discoveries, Utrecht, the Netherlands
| | - Tim Dielen
- Hubrecht Institute\KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584CT Utrecht, the Netherlands
| | - Lina Seneby
- Hubrecht Institute\KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584CT Utrecht, the Netherlands
| | - Gitanjali Dharmadhikari
- Hubrecht Institute\KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584CT Utrecht, the Netherlands
| | - Gerard Gradwohl
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Université de Strasbourg, Strasbourg, France
| | - Alexander van Oudenaarden
- Hubrecht Institute\KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584CT Utrecht, the Netherlands
- Single Cell Discoveries, Utrecht, the Netherlands
- Oncode Institute, the Netherlands
| | - Eelco J. P. de Koning
- Hubrecht Institute\KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584CT Utrecht, the Netherlands
- Department of Internal Medicine, Leiden University Medical Center, Leiden, the Netherlands
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35
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Haliyur R, Tong X, Sanyoura M, Shrestha S, Lindner J, Saunders DC, Aramandla R, Poffenberger G, Redick SD, Bottino R, Prasad N, Levy SE, Blind RD, Harlan DM, Philipson LH, Stein RW, Brissova M, Powers AC. Human islets expressing HNF1A variant have defective β cell transcriptional regulatory networks. J Clin Invest 2018; 129:246-251. [PMID: 30507613 DOI: 10.1172/jci121994] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 10/24/2018] [Indexed: 01/06/2023] Open
Abstract
Using an integrated approach to characterize the pancreatic tissue and isolated islets from a 33-year-old with 17 years of type 1 diabetes (T1D), we found that donor islets contained β cells without insulitis and lacked glucose-stimulated insulin secretion despite a normal insulin response to cAMP-evoked stimulation. With these unexpected findings for T1D, we sequenced the donor DNA and found a pathogenic heterozygous variant in the gene encoding hepatocyte nuclear factor-1α (HNF1A). In one of the first studies of human pancreatic islets with a disease-causing HNF1A variant associated with the most common form of monogenic diabetes, we found that HNF1A dysfunction leads to insulin-insufficient diabetes reminiscent of T1D by impacting the regulatory processes critical for glucose-stimulated insulin secretion and suggest a rationale for a therapeutic alternative to current treatment.
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Affiliation(s)
- Rachana Haliyur
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
| | - Xin Tong
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
| | - May Sanyoura
- Departments of Medicine and Pediatrics-Endocrinology, Diabetes, and Metabolism, University of Chicago, Chicago, Illinois, USA
| | - Shristi Shrestha
- HudsonAlpha Institute for Biotechnology, Huntsville, Alabama, USA
| | - Jill Lindner
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Diane C Saunders
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
| | - Radhika Aramandla
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Greg Poffenberger
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Sambra D Redick
- Department of Medicine, Diabetes Center of Excellence, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Rita Bottino
- Institute of Cellular Therapeutics, Allegheny Health Network, Pittsburgh, Pennsylvania, USA
| | - Nripesh Prasad
- HudsonAlpha Institute for Biotechnology, Huntsville, Alabama, USA
| | - Shawn E Levy
- HudsonAlpha Institute for Biotechnology, Huntsville, Alabama, USA
| | - Raymond D Blind
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA.,Departments of Pharmacology and Biochemistry, Vanderbilt University, Nashville, Tennessee, USA
| | - David M Harlan
- Department of Medicine, Diabetes Center of Excellence, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Louis H Philipson
- Departments of Medicine and Pediatrics-Endocrinology, Diabetes, and Metabolism, University of Chicago, Chicago, Illinois, USA
| | - Roland W Stein
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA
| | - Marcela Brissova
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Alvin C Powers
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, USA.,Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA.,Veterans Affairs Tennessee Valley Healthcare System, Nashville, Tennessee, USA
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Groebe K, Cen J, Schvartz D, Sargsyan E, Chowdhury A, Roomp K, Schneider R, Alderborn A, Sanchez JC, Bergsten P. Palmitate-Induced Insulin Hypersecretion and Later Secretory Decline Associated with Changes in Protein Expression Patterns in Human Pancreatic Islets. J Proteome Res 2018; 17:3824-3836. [PMID: 30183308 DOI: 10.1021/acs.jproteome.8b00239] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In obese children with high circulating concentrations of free fatty acid palmitate, we have observed that insulin levels at fasting and in response to a glucose challenge were several times higher than in obese children with low concentrations of the fatty acid as well as in lean controls. Declining and even insufficient insulin levels were observed in obese adolescents with high levels of the fatty acid. In isolated human islets exposed to palmitate we have observed insulin hypersecretion after 2 days exposure. In contrast, insulin secretion from the islets was reduced after 7 days culture in the presence of the fatty acid. This study aims at identifying islet-related biological events potentially linked with the observed insulin hypersecretion and later secretory decline in these obese children and adolescents using the islet model. We analyzed protein expression data obtained from human islets exposed to elevated palmitate levels for 2 and 7 days by an improved methodology for statistical analysis of differentially expressed proteins. Protein profiling of islet samples by liquid chromatography-tandem mass spectrometry identified 115 differentially expressed proteins (DEPs). Several DEPs including sorcin were associated with increased glucose-stimulated insulin secretion in islets after 2 days of exposure to palmitate. Similarly, several metabolic pathways including altered protein degradation, increased autophagy, altered redox condition, and hampered insulin processing were coupled to the functional impairment of islets after 7 days of culture in the presence of palmitate. Such biological events, once validated in the islets, may give rise to novel treatment strategies aiming at normalizing insulin levels in obese children with high palmitate levels, which may reduce or even prevent obesity-related type 2 diabetes mellitus.
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Affiliation(s)
| | - Jing Cen
- Department of Medical Cell Biology , Uppsala University , 75236 Uppsala , Sweden
| | - Domitille Schvartz
- Human Protein Sciences Department, Centre Medical Universitaire , University of Geneva , CH-1211 Geneva , Switzerland
| | - Ernest Sargsyan
- Department of Medical Cell Biology , Uppsala University , 75236 Uppsala , Sweden
| | - Azazul Chowdhury
- Department of Medical Cell Biology , Uppsala University , 75236 Uppsala , Sweden
| | - Kirsten Roomp
- Luxembourg Centre for Systems Biomedicine , University of Luxembourg , 4365 Esch-sur-Alzette , Luxembourg
| | - Reinhard Schneider
- Luxembourg Centre for Systems Biomedicine , University of Luxembourg , 4365 Esch-sur-Alzette , Luxembourg
| | - Anders Alderborn
- Department of Medical Cell Biology , Uppsala University , 75236 Uppsala , Sweden
| | - Jean-Charles Sanchez
- Human Protein Sciences Department, Centre Medical Universitaire , University of Geneva , CH-1211 Geneva , Switzerland
| | - Peter Bergsten
- Department of Medical Cell Biology , Uppsala University , 75236 Uppsala , Sweden
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Taneera J, Prasad RB, Dhaiban S, Mohammed AK, Haataja L, Arvan P, Hamad M, Groop L, Wollheim CB. Silencing of the FTO gene inhibits insulin secretion: An in vitro study using GRINCH cells. Mol Cell Endocrinol 2018; 472:10-17. [PMID: 29890211 PMCID: PMC6559235 DOI: 10.1016/j.mce.2018.06.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 05/14/2018] [Accepted: 06/07/2018] [Indexed: 01/01/2023]
Abstract
Expression of fat mass and obesity-associated gene (FTO) and ADP-ribosylation factor-like 15 (ARL15) in human islets is inversely correlated with HbA1c. However, their impact on insulin secretion is still ambiguous. Here in, we investigated the role of FTO and ARL15 using GRINCH (Glucose-Responsive Insulin-secreting C-peptide-modified Human proinsulin) clonal rat β-cells. GRINCH cells have inserted GFP into the human C-peptide insulin gene. Hence, secreted CpepGFP served to monitor insulin secretion. mRNA silencing of FTO in GRINCH cells showed a significant reduction in glucose but not depolarization-stimulated insulin secretion, whereas ARL15 silencing had no effect. A significant down-regulation of insulin mRNA was observed in FTO knockdown cells. Type-2 Diabetic islets revealed a reduced expression of FTO mRNA. In conclusion, our data suggest that fluorescent CpepGFP released from GRINCH cells may serve as a convenient marker for insulin secretion. Silencing of FTO expression, but not ARL15, inhibits insulin secretion by affecting metabolic signaling.
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Affiliation(s)
- Jalal Taneera
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates; Lund University Diabetes Center, Malmoe, Lund University, Sweden.
| | - Rashmi B Prasad
- Lund University Diabetes Center, Malmoe, Lund University, Sweden
| | - Sarah Dhaiban
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates
| | - Abdul Khader Mohammed
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates
| | - Leena Haataja
- Endocrinology and Diabetes, University of Michigan Medical School, Ann Arbor, USA
| | - Peter Arvan
- Endocrinology and Diabetes, University of Michigan Medical School, Ann Arbor, USA
| | - Mawieh Hamad
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates
| | - Leif Groop
- Lund University Diabetes Center, Malmoe, Lund University, Sweden; Finnish Institute for Molecular Medicine (FIMM), Helsinki University, Finland
| | - Claes B Wollheim
- Lund University Diabetes Center, Malmoe, Lund University, Sweden; Department of Cell Physiology and Metabolism, University Medical Center. Geneva, Switzerland
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38
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Meta-analyses of the association of G6PC2 allele variants with elevated fasting glucose and type 2 diabetes. PLoS One 2017; 12:e0181232. [PMID: 28704540 PMCID: PMC5509327 DOI: 10.1371/journal.pone.0181232] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 06/28/2017] [Indexed: 12/19/2022] Open
Abstract
Objective To collectively evaluate the association of glucose-6-phosphatase catalytic unit 2 (G6PC2) allele variants with elevated fasting glucose (FG) and type 2 diabetes (T2D). Design Meta-analysis Data sources PubMed, Web of Knowledge and Embase databases. Study selection Full text articles of studies that identified an association of G6PC2 with T2D and elevated FG. Patient involvement There was no T2D patient involvement in the analyses on the association of FG with G6PC2, there were T2D patients and non-diabetes patient involvement in the analyses on the association of T2D with G6PC2. Statistical analysis Random-effects meta-analyses were used to calculate the pool effect sizes. I2 metric and H2 tests were used to calculate the heterogeneity. Begg's funnel plot and Egger’s linear regression test were done to assess publication bias. Results Of the 423 studies identified, 21 were eligible and included. Data on three loci (rs560887, rs16856187 and rs573225) were available. The G allele at rs560887 in three ethnicities, the C allele at rs16856187 and the A allele at rs573225 all had a positive association with elevated FG. Per increment of G allele at rs560887 and A allele at rs573225 resulted in a FG 0.070 mmol/l and 0.075 mmol/l higher (ß (95% CI) = 0.070 (0.060, 0.079), p = 4.635e-50 and 0.075 (0.065, 0.085), p = 5.856e-48, respectively). With regard to the relationship of rs16856187 and FG, an increase of 0.152 (95% CI: 0.034–0.270; p = 0.011) and 0.317 (95% CI: 0.193–0.442, p = 6.046e-07) was found in the standardized mean difference (SMD) of FG for the AC and CC genotypes, respectively, when compared with the AA reference genotype. However, the G-allele of rs560887 in Caucasians under the additive model and the C-allele of rs16856187 under the allele and dominant models were associated with a decreased risk of T2D (OR (95% CI) = 0.964 (0.947, 0.981), p = 0.570e-4; OR (95% CI) = 0.892 (0.832, 0.956), p = 0.001; and OR (95% CI) = 0.923(0.892, 0.955), p = 5.301e-6, respectively). Conclusions Our meta-analyses demonstrate that all three allele variants of G6PC2 (rs560887, rs16856187 and rs573225) are associated with elevated FG, with two variants (rs560887 in the Caucasians subgroup and rs16856187 under the allele and dominant model) being associated with T2D as well. Further studies utilizing larger sample sizes and different ethnic populations are needed to extend and confirm these findings.
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Ashcroft FM, Rohm M, Clark A, Brereton MF. Is Type 2 Diabetes a Glycogen Storage Disease of Pancreatic β Cells? Cell Metab 2017; 26:17-23. [PMID: 28683284 PMCID: PMC5890904 DOI: 10.1016/j.cmet.2017.05.014] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 04/24/2017] [Accepted: 05/24/2017] [Indexed: 11/17/2022]
Abstract
Elevated plasma glucose leads to pancreatic β cell dysfunction and death in type 2 diabetes. Glycogen accumulation, due to impaired metabolism, contributes to this "glucotoxicity" via dysregulated biochemical pathways promoting β cell dysfunction. Here, we review emerging data, and re-examine published findings, on the role of glycogen in β cells in normoglycemia and in diabetes.
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Affiliation(s)
- Frances M Ashcroft
- Department of Physiology, Anatomy, and Genetics and OXION, University of Oxford, Parks Road, Oxford OX1 3PT, UK.
| | - Maria Rohm
- Department of Physiology, Anatomy, and Genetics and OXION, University of Oxford, Parks Road, Oxford OX1 3PT, UK
| | - Anne Clark
- Oxford Centre for Diabetes, Endocrinology, and Metabolism, University of Oxford, Churchill Hospital, Oxford OX3 7LJ, UK
| | - Melissa F Brereton
- Department of Physiology, Anatomy, and Genetics and OXION, University of Oxford, Parks Road, Oxford OX1 3PT, UK
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van der Meulen T, Mawla AM, DiGruccio MR, Adams MW, Nies V, Dólleman S, Liu S, Ackermann AM, Cáceres E, Hunter AE, Kaestner KH, Donaldson CJ, Huising MO. Virgin Beta Cells Persist throughout Life at a Neogenic Niche within Pancreatic Islets. Cell Metab 2017; 25:911-926.e6. [PMID: 28380380 PMCID: PMC8586897 DOI: 10.1016/j.cmet.2017.03.017] [Citation(s) in RCA: 147] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 02/14/2017] [Accepted: 03/21/2017] [Indexed: 12/21/2022]
Abstract
Postnatal maintenance or regeneration of pancreatic beta cells is considered to occur exclusively via the replication of existing beta cells, but clinically meaningful restoration of human beta cell mass by proliferation has never been achieved. We discovered a population of immature beta cells that is present throughout life and forms from non-beta precursors at a specialized micro-environment or "neogenic niche" at the islet periphery. These cells express insulin, but lack other key beta cell markers, and are transcriptionally immature, incapable of sensing glucose, and unable to support calcium influx. They constitute an intermediate stage in the transdifferentiation of alpha cells to cells that are functionally indistinguishable from conventional beta cells. We thus identified a lifelong source of new beta cells at a specialized site within healthy islets. By comparing co-existing immature and mature beta cells within healthy islets, we stand to learn how to mature insulin-expressing cells into functional beta cells.
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Affiliation(s)
- Talitha van der Meulen
- Department of Neurobiology, Physiology, and Behavior, College of Biological Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Alex M Mawla
- Department of Neurobiology, Physiology, and Behavior, College of Biological Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Michael R DiGruccio
- Department of Neurobiology, Physiology, and Behavior, College of Biological Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Michael W Adams
- Waitt Advanced Biophotonics Center, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Vera Nies
- Clayton Foundation Laboratories for Peptide Biology, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Sophie Dólleman
- Clayton Foundation Laboratories for Peptide Biology, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Siming Liu
- Department of Neurobiology, Physiology, and Behavior, College of Biological Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Amanda M Ackermann
- Division of Endocrinology and Diabetes, The Children's Hospital of Philadelphia, 3400 Civic Center Boulevard, Philadelphia, PA 19104, USA
| | - Elena Cáceres
- Clayton Foundation Laboratories for Peptide Biology, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Anna E Hunter
- Department of Neurobiology, Physiology, and Behavior, College of Biological Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Klaus H Kaestner
- Department of Genetics and Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Cynthia J Donaldson
- Clayton Foundation Laboratories for Peptide Biology, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Mark O Huising
- Department of Neurobiology, Physiology, and Behavior, College of Biological Sciences, University of California, Davis, Davis, CA 95616, USA; Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, Davis, CA 95616, USA.
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Boortz KA, Syring KE, Pound LD, Mo H, Bastarache L, Oeser JK, McGuinness OP, Denny JC, O’Brien RM. Effects of G6pc2 deletion on body weight and cholesterol in mice. J Mol Endocrinol 2017; 58:127-139. [PMID: 28122818 PMCID: PMC5380368 DOI: 10.1530/jme-16-0202] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 01/24/2017] [Indexed: 11/08/2022]
Abstract
Genome-wide association study (GWAS) data have linked the G6PC2 gene to variations in fasting blood glucose (FBG). G6PC2 encodes an islet-specific glucose-6-phosphatase catalytic subunit that forms a substrate cycle with the beta cell glucose sensor glucokinase. This cycle modulates the glucose sensitivity of insulin secretion and hence FBG. GWAS data have not linked G6PC2 to variations in body weight but we previously reported that female C57BL/6J G6pc2-knockout (KO) mice were lighter than wild-type littermates on both a chow and high-fat diet. The purpose of this study was to compare the effects of G6pc2 deletion on FBG and body weight in both chow-fed and high-fat-fed mice on two other genetic backgrounds. FBG was reduced in G6pc2 KO mice largely independent of gender, genetic background or diet. In contrast, the effect of G6pc2 deletion on body weight was markedly influenced by these variables. Deletion of G6pc2 conferred a marked protection against diet-induced obesity in male mixed genetic background mice, whereas in 129SvEv mice deletion of G6pc2 had no effect on body weight. G6pc2 deletion also reduced plasma cholesterol levels in a manner dependent on gender, genetic background and diet. An association between G6PC2 and plasma cholesterol was also observed in humans through electronic health record-derived phenotype analyses. These observations suggest that the action of G6PC2 on FBG is largely independent of the influences of environment, modifier genes or epigenetic events, whereas the action of G6PC2 on body weight and cholesterol are influenced by unknown variables.
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Affiliation(s)
- Kayla A. Boortz
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Kristen E. Syring
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Lynley D. Pound
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Huan Mo
- Department of Biomedical Informatics, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Lisa Bastarache
- Department of Biomedical Informatics, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - James K. Oeser
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Owen P. McGuinness
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Joshua C. Denny
- Department of Biomedical Informatics, Vanderbilt University School of Medicine, Nashville, TN 37232
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Richard M. O’Brien
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232
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Andersson LE, Nicholas LM, Filipsson K, Sun J, Medina A, Al-Majdoub M, Fex M, Mulder H, Spégel P. Glycogen metabolism in the glucose-sensing and supply-driven β-cell. FEBS Lett 2016; 590:4242-4251. [PMID: 27943300 DOI: 10.1002/1873-3468.12460] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Revised: 07/25/2016] [Accepted: 09/29/2016] [Indexed: 12/24/2022]
Abstract
Glycogen metabolism in β-cells may affect downstream metabolic pathways controlling insulin release. We examined glycogen metabolism in human islets and in the rodent-derived INS-1 832/13 β-cells and found them to express the same isoforms of key enzymes required for glycogen metabolism. Our findings indicate that glycogenesis is insulin-independent but influenced by extracellular glucose concentrations. Levels of glycogen synthase decrease with increasing glucose concentrations, paralleling accumulation of glycogen. We did not find cAMP-elicited glycogenolysis and insulin secretion to be causally related. In conclusion, our results reveal regulated glycogen metabolism in human islets and insulin-secreting cells. Whether glycogen metabolism affects insulin secretion under physiological conditions remains to be determined.
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Affiliation(s)
- Lotta E Andersson
- Department of Clinical Sciences, Unit of Molecular Metabolism, Lund University Diabetes Centre, CRC, Malmö, Sweden
| | - Lisa M Nicholas
- Department of Clinical Sciences, Unit of Molecular Metabolism, Lund University Diabetes Centre, CRC, Malmö, Sweden
| | - Karin Filipsson
- Department of Clinical Sciences, Unit of Molecular Metabolism, Lund University Diabetes Centre, CRC, Malmö, Sweden
| | - Jiangming Sun
- Department of Clinical Sciences, Unit of Molecular Metabolism, Lund University Diabetes Centre, CRC, Malmö, Sweden
| | - Anya Medina
- Department of Clinical Sciences, Unit of Molecular Metabolism, Lund University Diabetes Centre, CRC, Malmö, Sweden
| | - Mahmoud Al-Majdoub
- Department of Clinical Sciences, Unit of Molecular Metabolism, Lund University Diabetes Centre, CRC, Malmö, Sweden
| | - Malin Fex
- Department of Clinical Sciences, Unit of Molecular Metabolism, Lund University Diabetes Centre, CRC, Malmö, Sweden
| | - Hindrik Mulder
- Department of Clinical Sciences, Unit of Molecular Metabolism, Lund University Diabetes Centre, CRC, Malmö, Sweden
| | - Peter Spégel
- Department of Clinical Sciences, Unit of Molecular Metabolism, Lund University Diabetes Centre, CRC, Malmö, Sweden.,Department of Chemistry, Centre for Analysis and Synthesis, Lund University, Sweden
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Boortz KA, Syring KE, Lee RA, Dai C, Oeser JK, McGuinness OP, Wang JC, O'Brien RM. G6PC2 Modulates the Effects of Dexamethasone on Fasting Blood Glucose and Glucose Tolerance. Endocrinology 2016; 157:4133-4145. [PMID: 27653037 PMCID: PMC5086534 DOI: 10.1210/en.2016-1678] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The glucose-6-phosphatase catalytic subunit 2 (G6PC2) gene encodes an islet-specific glucose-6-phosphatase catalytic subunit. G6PC2 forms a substrate cycle with glucokinase that determines the glucose sensitivity of insulin secretion. Consequently, deletion of G6pc2 lowers fasting blood glucose (FBG) without affecting fasting plasma insulin. Although chronic elevation of FBG is detrimental to health, glucocorticoids induce G6PC2 expression, suggesting that G6PC2 evolved to transiently modulate FBG under conditions of glucocorticoid-related stress. We show, using competition and mutagenesis experiments, that the synthetic glucocorticoid dexamethasone (Dex) induces G6PC2 promoter activity through a mechanism involving displacement of the islet-enriched transcription factor MafA by the glucocorticoid receptor. The induction of G6PC2 promoter activity by Dex is modulated by a single nucleotide polymorphism, previously linked to altered FBG in humans, that affects FOXA2 binding. A 5-day repeated injection paradigm was used to examine the chronic effect of Dex on FBG and glucose tolerance in wild-type (WT) and G6pc2 knockout mice. Acute Dex treatment only induces G6pc2 expression in 129SvEv but not C57BL/6J mice, but this chronic treatment induced G6pc2 expression in both. In 6-hour fasted C57BL/6J WT mice, Dex treatment lowered FBG and improved glucose tolerance, with G6pc2 deletion exacerbating the decrease in FBG and enhancing the improvement in glucose tolerance. In contrast, in 24-hour fasted C57BL/6J WT mice, Dex treatment raised FBG but still improved glucose tolerance, with G6pc2 deletion limiting the increase in FBG and enhancing the improvement in glucose tolerance. These observations demonstrate that G6pc2 modulates the complex effects of Dex on both FBG and glucose tolerance.
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Affiliation(s)
- Kayla A Boortz
- Departments of Molecular Physiology and Biophysics (K.A.B., K.E.S., J.K.O., O.P.M., R.M.O.) and Medicine (C.D.), Vanderbilt University School of Medicine, Nashville, Tennessee 37232; and Department of Nutritional Sciences and Toxicology (R.A.L., J.-C.W.), University of California at Berkeley, Berkeley, California 94720
| | - Kristen E Syring
- Departments of Molecular Physiology and Biophysics (K.A.B., K.E.S., J.K.O., O.P.M., R.M.O.) and Medicine (C.D.), Vanderbilt University School of Medicine, Nashville, Tennessee 37232; and Department of Nutritional Sciences and Toxicology (R.A.L., J.-C.W.), University of California at Berkeley, Berkeley, California 94720
| | - Rebecca A Lee
- Departments of Molecular Physiology and Biophysics (K.A.B., K.E.S., J.K.O., O.P.M., R.M.O.) and Medicine (C.D.), Vanderbilt University School of Medicine, Nashville, Tennessee 37232; and Department of Nutritional Sciences and Toxicology (R.A.L., J.-C.W.), University of California at Berkeley, Berkeley, California 94720
| | - Chunhua Dai
- Departments of Molecular Physiology and Biophysics (K.A.B., K.E.S., J.K.O., O.P.M., R.M.O.) and Medicine (C.D.), Vanderbilt University School of Medicine, Nashville, Tennessee 37232; and Department of Nutritional Sciences and Toxicology (R.A.L., J.-C.W.), University of California at Berkeley, Berkeley, California 94720
| | - James K Oeser
- Departments of Molecular Physiology and Biophysics (K.A.B., K.E.S., J.K.O., O.P.M., R.M.O.) and Medicine (C.D.), Vanderbilt University School of Medicine, Nashville, Tennessee 37232; and Department of Nutritional Sciences and Toxicology (R.A.L., J.-C.W.), University of California at Berkeley, Berkeley, California 94720
| | - Owen P McGuinness
- Departments of Molecular Physiology and Biophysics (K.A.B., K.E.S., J.K.O., O.P.M., R.M.O.) and Medicine (C.D.), Vanderbilt University School of Medicine, Nashville, Tennessee 37232; and Department of Nutritional Sciences and Toxicology (R.A.L., J.-C.W.), University of California at Berkeley, Berkeley, California 94720
| | - Jen-Chywan Wang
- Departments of Molecular Physiology and Biophysics (K.A.B., K.E.S., J.K.O., O.P.M., R.M.O.) and Medicine (C.D.), Vanderbilt University School of Medicine, Nashville, Tennessee 37232; and Department of Nutritional Sciences and Toxicology (R.A.L., J.-C.W.), University of California at Berkeley, Berkeley, California 94720
| | - Richard M O'Brien
- Departments of Molecular Physiology and Biophysics (K.A.B., K.E.S., J.K.O., O.P.M., R.M.O.) and Medicine (C.D.), Vanderbilt University School of Medicine, Nashville, Tennessee 37232; and Department of Nutritional Sciences and Toxicology (R.A.L., J.-C.W.), University of California at Berkeley, Berkeley, California 94720
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Ward WO, Kodavanti UP. Pulmonary transcriptional response to ozone in healthy and cardiovascular compromised rat models. Inhal Toxicol 2016; 27 Suppl 1:93-104. [PMID: 26667334 DOI: 10.3109/08958378.2014.954173] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The genetic cardiovascular disease (CVD) and associated metabolic impairments can influence the lung injury from inhaled pollutants. We hypothesized that comparative assessment of global pulmonary expression profile of healthy and CVD-prone rat models will provide mechanistic insights into susceptibility differences to ozone. The lung expression profiles of healthy Wistar Kyoto (WKY) and CVD-compromised spontaneously hypertensive (SH), stroke-prone SH (SHSP), obese SH heart failure (SHHF) and obese, atherosclerosis-prone JCR rats were analyzed using Affymetrix platform immediately after 4-h air or 1 ppm ozone exposure. At baseline, the JCR exhibited the largest difference in the number of genes among all strains when compared with WKY. Interestingly, the number of genes affected by ozone was inversely correlated with genes different at baseline relative to WKY. A cluster of NFkB target genes involved in cell-adhesion, antioxidant response, inflammation and apoptosis was induced in all strains, albeit at different levels (JCR < WKY < SHHF < SH < SHSP). The lung metabolic syndrome gene cluster indicated expressions in opposite directions for SHHF and JCR suggesting different mechanisms for common disease phenotype and perhaps obesity-independent contribution to exacerbated lung disease. The differences in expression of adrenergic receptors and ion-channel genes suggested distinct mechanisms by which ozone might induce protein leakage in CVD models, especially SHHF and JCR. Thus, the pulmonary response to ozone in CVD strains was likely linked to the defining gene expression profiles. Differential transcriptional patterns between healthy and CVD rat strains at baseline, and after ozone suggests that lung inflammation and injury might be influenced by multiple biological pathways affecting inflammation gene signatures.
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Affiliation(s)
- William O Ward
- a Research Cores Unit, National Health and Environmental Effects Research Laboratory, Office of Research and Development, US Environmental Protection Agency , Research Triangle Park , NC , USA and
| | - Urmila P Kodavanti
- b Environmental Public Health Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, US Environmental Protection Agency , Research Triangle Park , NC , USA
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Functional Analysis of Mouse G6pc1 Mutations Using a Novel In Situ Assay for Glucose-6-Phosphatase Activity and the Effect of Mutations in Conserved Human G6PC1/G6PC2 Amino Acids on G6PC2 Protein Expression. PLoS One 2016; 11:e0162439. [PMID: 27611587 PMCID: PMC5017610 DOI: 10.1371/journal.pone.0162439] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2016] [Accepted: 08/23/2016] [Indexed: 11/19/2022] Open
Abstract
Elevated fasting blood glucose (FBG) has been associated with increased risk for development of type 2 diabetes. Single nucleotide polymorphisms (SNPs) in G6PC2 are the most important common determinants of variations in FBG in humans. Studies using G6pc2 knockout mice suggest that G6pc2 regulates the glucose sensitivity of insulin secretion. G6PC2 and the related G6PC1 and G6PC3 genes encode glucose-6-phosphatase catalytic subunits. This study describes a functional analysis of 22 non-synonymous G6PC2 SNPs, that alter amino acids that are conserved in human G6PC1, mouse G6pc1 and mouse G6pc2, with the goal of identifying variants that potentially affect G6PC2 activity/expression. Published data suggest strong conservation of catalytically important amino acids between all four proteins and the related G6PC3 isoform. Because human G6PC2 has very low glucose-6-phosphatase activity we used an indirect approach, examining the effect of these SNPs on mouse G6pc1 activity. Using a novel in situ functional assay for glucose-6-phosphatase activity we demonstrate that the amino acid changes associated with the human G6PC2 rs144254880 (Arg79Gln), rs149663725 (Gly114Arg) and rs2232326 (Ser324Pro) SNPs reduce mouse G6pc1 enzyme activity without affecting protein expression. The Arg79Gln variant alters an amino acid mutation of which, in G6PC1, has previously been shown to cause glycogen storage disease type 1a. We also demonstrate that the rs368382511 (Gly8Glu), rs138726309 (His177Tyr), rs2232323 (Tyr207Ser) rs374055555 (Arg293Trp), rs2232326 (Ser324Pro), rs137857125 (Pro313Leu) and rs2232327 (Pro340Leu) SNPs confer decreased G6PC2 protein expression. In summary, these studies identify multiple G6PC2 variants that have the potential to be associated with altered FBG in humans.
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Boortz KA, Syring KE, Dai C, Pound LD, Oeser JK, Jacobson DA, Wang JC, McGuinness OP, Powers AC, O'Brien RM. G6PC2 Modulates Fasting Blood Glucose In Male Mice in Response to Stress. Endocrinology 2016; 157:3002-8. [PMID: 27300767 PMCID: PMC4967123 DOI: 10.1210/en.2016-1245] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The glucose-6-phosphatase catalytic 2 (G6PC2) gene is expressed specifically in pancreatic islet beta cells. Genome-wide association studies have shown that single nucleotide polymorphisms in the G6PC2 gene are associated with variations in fasting blood glucose (FBG) but not fasting plasma insulin. Molecular analyses examining the functional effects of these single nucleotide polymorphisms demonstrate that elevated G6PC2 expression is associated with elevated FBG. Studies in mice complement these genome-wide association data and show that deletion of the G6pc2 gene lowers FBG without affecting fasting plasma insulin. This suggests that, together with glucokinase, G6PC2 forms a substrate cycle that determines the glucose sensitivity of insulin secretion. Because genome-wide association studies and mouse studies demonstrate that elevated G6PC2 expression raises FBG and because chronically elevated FBG is detrimental to human health, increasing the risk of type 2 diabetes, it is unclear why G6PC2 evolved. We show here that the synthetic glucocorticoid dexamethasone strongly induces human G6PC2 promoter activity and endogenous G6PC2 expression in isolated human islets. Acute treatment with dexamethasone selectively induces endogenous G6pc2 expression in 129SvEv but not C57BL/6J mouse pancreas and isolated islets. The difference is due to a single nucleotide polymorphism in the C57BL/6J G6pc2 promoter that abolishes glucocorticoid receptor binding. In 6-hour fasted, nonstressed 129SvEv mice, deletion of G6pc2 lowers FBG. In response to the stress of repeated physical restraint, which is associated with elevated plasma glucocorticoid levels, G6pc2 gene expression is induced and the difference in FBG between wild-type and knockout mice is enhanced. These data suggest that G6PC2 may have evolved to modulate FBG in response to stress.
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Affiliation(s)
- Kayla A Boortz
- Departments of Molecular Physiology and Biophysics (K.A.B., K.E.S., L.D.P., J.K.O., D.A.J., O.P.M., R.M.O.) and Medicine (C.D., A.C.P.), Vanderbilt University School of Medicine, and VA Tennessee Valley Healthcare System (A.C.P.), Nashville, Tennessee 37232-0615; and Department of Nutritional Sciences and Toxicology (J.-C.W.), University of California, Berkeley, Berkeley, California 94720-3104
| | - Kristen E Syring
- Departments of Molecular Physiology and Biophysics (K.A.B., K.E.S., L.D.P., J.K.O., D.A.J., O.P.M., R.M.O.) and Medicine (C.D., A.C.P.), Vanderbilt University School of Medicine, and VA Tennessee Valley Healthcare System (A.C.P.), Nashville, Tennessee 37232-0615; and Department of Nutritional Sciences and Toxicology (J.-C.W.), University of California, Berkeley, Berkeley, California 94720-3104
| | - Chunhua Dai
- Departments of Molecular Physiology and Biophysics (K.A.B., K.E.S., L.D.P., J.K.O., D.A.J., O.P.M., R.M.O.) and Medicine (C.D., A.C.P.), Vanderbilt University School of Medicine, and VA Tennessee Valley Healthcare System (A.C.P.), Nashville, Tennessee 37232-0615; and Department of Nutritional Sciences and Toxicology (J.-C.W.), University of California, Berkeley, Berkeley, California 94720-3104
| | - Lynley D Pound
- Departments of Molecular Physiology and Biophysics (K.A.B., K.E.S., L.D.P., J.K.O., D.A.J., O.P.M., R.M.O.) and Medicine (C.D., A.C.P.), Vanderbilt University School of Medicine, and VA Tennessee Valley Healthcare System (A.C.P.), Nashville, Tennessee 37232-0615; and Department of Nutritional Sciences and Toxicology (J.-C.W.), University of California, Berkeley, Berkeley, California 94720-3104
| | - James K Oeser
- Departments of Molecular Physiology and Biophysics (K.A.B., K.E.S., L.D.P., J.K.O., D.A.J., O.P.M., R.M.O.) and Medicine (C.D., A.C.P.), Vanderbilt University School of Medicine, and VA Tennessee Valley Healthcare System (A.C.P.), Nashville, Tennessee 37232-0615; and Department of Nutritional Sciences and Toxicology (J.-C.W.), University of California, Berkeley, Berkeley, California 94720-3104
| | - David A Jacobson
- Departments of Molecular Physiology and Biophysics (K.A.B., K.E.S., L.D.P., J.K.O., D.A.J., O.P.M., R.M.O.) and Medicine (C.D., A.C.P.), Vanderbilt University School of Medicine, and VA Tennessee Valley Healthcare System (A.C.P.), Nashville, Tennessee 37232-0615; and Department of Nutritional Sciences and Toxicology (J.-C.W.), University of California, Berkeley, Berkeley, California 94720-3104
| | - Jen-Chywan Wang
- Departments of Molecular Physiology and Biophysics (K.A.B., K.E.S., L.D.P., J.K.O., D.A.J., O.P.M., R.M.O.) and Medicine (C.D., A.C.P.), Vanderbilt University School of Medicine, and VA Tennessee Valley Healthcare System (A.C.P.), Nashville, Tennessee 37232-0615; and Department of Nutritional Sciences and Toxicology (J.-C.W.), University of California, Berkeley, Berkeley, California 94720-3104
| | - Owen P McGuinness
- Departments of Molecular Physiology and Biophysics (K.A.B., K.E.S., L.D.P., J.K.O., D.A.J., O.P.M., R.M.O.) and Medicine (C.D., A.C.P.), Vanderbilt University School of Medicine, and VA Tennessee Valley Healthcare System (A.C.P.), Nashville, Tennessee 37232-0615; and Department of Nutritional Sciences and Toxicology (J.-C.W.), University of California, Berkeley, Berkeley, California 94720-3104
| | - Alvin C Powers
- Departments of Molecular Physiology and Biophysics (K.A.B., K.E.S., L.D.P., J.K.O., D.A.J., O.P.M., R.M.O.) and Medicine (C.D., A.C.P.), Vanderbilt University School of Medicine, and VA Tennessee Valley Healthcare System (A.C.P.), Nashville, Tennessee 37232-0615; and Department of Nutritional Sciences and Toxicology (J.-C.W.), University of California, Berkeley, Berkeley, California 94720-3104
| | - Richard M O'Brien
- Departments of Molecular Physiology and Biophysics (K.A.B., K.E.S., L.D.P., J.K.O., D.A.J., O.P.M., R.M.O.) and Medicine (C.D., A.C.P.), Vanderbilt University School of Medicine, and VA Tennessee Valley Healthcare System (A.C.P.), Nashville, Tennessee 37232-0615; and Department of Nutritional Sciences and Toxicology (J.-C.W.), University of California, Berkeley, Berkeley, California 94720-3104
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47
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Marmugi A, Parnis J, Chen X, Carmichael L, Hardy J, Mannan N, Marchetti P, Piemonti L, Bosco D, Johnson P, Shapiro JAM, Cruciani-Guglielmacci C, Magnan C, Ibberson M, Thorens B, Valdivia HH, Rutter GA, Leclerc I. Sorcin Links Pancreatic β-Cell Lipotoxicity to ER Ca2+ Stores. Diabetes 2016; 65:1009-21. [PMID: 26822088 PMCID: PMC4806657 DOI: 10.2337/db15-1334] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 01/18/2016] [Indexed: 01/02/2023]
Abstract
Preserving β-cell function during the development of obesity and insulin resistance would limit the worldwide epidemic of type 2 diabetes. Endoplasmic reticulum (ER) calcium (Ca(2+)) depletion induced by saturated free fatty acids and cytokines causes β-cell ER stress and apoptosis, but the molecular mechanisms behind these phenomena are still poorly understood. Here, we demonstrate that palmitate-induced sorcin downregulation and subsequent increases in glucose-6-phosphatase catalytic subunit-2 (G6PC2) levels contribute to lipotoxicity. Sorcin is a calcium sensor protein involved in maintaining ER Ca(2+) by inhibiting ryanodine receptor activity and playing a role in terminating Ca(2+)-induced Ca(2+) release. G6PC2, a genome-wide association study gene associated with fasting blood glucose, is a negative regulator of glucose-stimulated insulin secretion (GSIS). High-fat feeding in mice and chronic exposure of human islets to palmitate decreases endogenous sorcin expression while levels of G6PC2 mRNA increase. Sorcin-null mice are glucose intolerant, with markedly impaired GSIS and increased expression of G6pc2 Under high-fat diet, mice overexpressing sorcin in the β-cell display improved glucose tolerance, fasting blood glucose, and GSIS, whereas G6PC2 levels are decreased and cytosolic and ER Ca(2+) are increased in transgenic islets. Sorcin may thus provide a target for intervention in type 2 diabetes.
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Affiliation(s)
- Alice Marmugi
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology & Metabolism, Department of Medicine, Imperial College London, London, U.K
| | - Julia Parnis
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology & Metabolism, Department of Medicine, Imperial College London, London, U.K
| | - Xi Chen
- Center for Arrhythmia Research, University of Michigan, Ann Arbor, MI
| | - LeAnne Carmichael
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology & Metabolism, Department of Medicine, Imperial College London, London, U.K
| | - Julie Hardy
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology & Metabolism, Department of Medicine, Imperial College London, London, U.K
| | - Naila Mannan
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology & Metabolism, Department of Medicine, Imperial College London, London, U.K
| | - Piero Marchetti
- Department of Endocrinology and Metabolism, University of Pisa, Pisa, Italy
| | - Lorenzo Piemonti
- Diabetes Research Institute (HSR-DRI), San Raffaele Scientific Institute, Milan, Italy
| | - Domenico Bosco
- Cell Isolation and Transplantation Center, Department of Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | - Paul Johnson
- Nuffield Department of Surgical Sciences, University of Oxford, Oxford, U.K
| | - James A M Shapiro
- Clinical Islet Laboratory and Clinical Islet Transplant Program, University of Alberta, Edmonton, Alberta, Canada
| | | | - Christophe Magnan
- Unit of Functional and Adaptive Biology, Paris Diderot University-Paris 7, Paris, France
| | - Mark Ibberson
- Vital-IT Group, SIB Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Bernard Thorens
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
| | - Héctor H Valdivia
- Center for Arrhythmia Research, University of Michigan, Ann Arbor, MI
| | - Guy A Rutter
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology & Metabolism, Department of Medicine, Imperial College London, London, U.K.
| | - Isabelle Leclerc
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology & Metabolism, Department of Medicine, Imperial College London, London, U.K.
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48
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Pound LD, Patrick C, Eberhard CE, Mottawea W, Wang GS, Abujamel T, Vandenbeek R, Stintzi A, Scott FW. Cathelicidin Antimicrobial Peptide: A Novel Regulator of Islet Function, Islet Regeneration, and Selected Gut Bacteria. Diabetes 2015; 64:4135-47. [PMID: 26370175 DOI: 10.2337/db15-0788] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 08/22/2015] [Indexed: 11/13/2022]
Abstract
Cathelicidin antimicrobial peptide (CAMP) is a naturally occurring secreted peptide that is expressed in several organs with pleiotropic roles in immunomodulation, wound healing, and cell growth. We previously demonstrated that gut Camp expression is upregulated when type 1 diabetes-prone rats are protected from diabetes development. Unexpectedly, we have also identified novel CAMP expression in the pancreatic β-cells of rats, mice, and humans. CAMP was present even in sterile rat embryo islets, germ-free adult rat islets, and neogenic tubular complexes. Camp gene expression was downregulated in young BBdp rat islets before the onset of insulitis compared with control BBc rats. CAMP treatment of dispersed islets resulted in a significant increase in intracellular calcium mobilization, an effect that was both delayed and blunted in the absence of extracellular calcium. Additionally, CAMP treatment promoted insulin and glucagon secretion from isolated rat islets. Thus, CAMP is a promoter of islet paracrine signaling that enhances islet function and glucoregulation. Finally, daily treatment with the CAMP/LL-37 peptide in vivo in BBdp rats resulted in enhanced β-cell neogenesis and upregulation of potentially beneficial gut microbes. In particular, CAMP/LL-37 treatment shifted the abundance of specific bacterial populations, mitigating the gut dysbiosis observed in the BBdp rat. Taken together, these findings indicate a novel functional role for CAMP/LL-37 in islet biology and modification of gut microbiota.
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Affiliation(s)
- Lynley D Pound
- Chronic Disease Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Christopher Patrick
- Chronic Disease Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Chandra E Eberhard
- Chronic Disease Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Walid Mottawea
- Ottawa Institute of Systems Biology, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada Department of Microbiology and Immunology, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt
| | - Gen-Sheng Wang
- Chronic Disease Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Turki Abujamel
- Ottawa Institute of Systems Biology, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
| | - Roxanne Vandenbeek
- Chronic Disease Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Alain Stintzi
- Ottawa Institute of Systems Biology, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
| | - Fraser W Scott
- Chronic Disease Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada Department of Medicine, University of Ottawa, Ottawa, Ontario, Canada
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49
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Wall ML, Pound LD, Trenary I, O'Brien RM, Young JD. Novel stable isotope analyses demonstrate significant rates of glucose cycling in mouse pancreatic islets. Diabetes 2015; 64:2129-37. [PMID: 25552595 PMCID: PMC4439557 DOI: 10.2337/db14-0745] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2014] [Accepted: 12/20/2014] [Indexed: 11/20/2022]
Abstract
A polymorphism located in the G6PC2 gene, which encodes an islet-specific glucose-6-phosphatase catalytic subunit, is the most important common determinant of variations in fasting blood glucose (FBG) levels in humans. Studies of G6pc2 knockout (KO) mice suggest that G6pc2 represents a negative regulator of basal glucose-stimulated insulin secretion (GSIS) that acts by hydrolyzing glucose-6-phosphate (G6P), thereby reducing glycolytic flux. However, this conclusion conflicts with the very low estimates for the rate of glucose cycling in pancreatic islets, as assessed using radioisotopes. We have reassessed the rate of glucose cycling in pancreatic islets using a novel stable isotope method. The data show much higher levels of glucose cycling than previously reported. In 5 mmol/L glucose, islets from C57BL/6J chow-fed mice cycled ∼16% of net glucose uptake. The cycling rate was further increased at 11 mmol/L glucose. Similar cycling rates were observed using islets from high fat-fed mice. Importantly, glucose cycling was abolished in G6pc2 KO mouse islets, confirming that G6pc2 opposes the action of the glucose sensor glucokinase by hydrolyzing G6P. The demonstration of high rates of glucose cycling in pancreatic islets explains why G6pc2 deletion enhances GSIS and why variants in G6PC2 affect FBG in humans.
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Affiliation(s)
- Martha L Wall
- Department of Chemical and Biomolecular Engineering, Vanderbilt School of Engineering, Nashville, TN
| | - Lynley D Pound
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical School, Nashville, TN
| | - Irina Trenary
- Department of Chemical and Biomolecular Engineering, Vanderbilt School of Engineering, Nashville, TN
| | - Richard M O'Brien
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical School, Nashville, TN
| | - Jamey D Young
- Department of Chemical and Biomolecular Engineering, Vanderbilt School of Engineering, Nashville, TN Department of Molecular Physiology and Biophysics, Vanderbilt University Medical School, Nashville, TN
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50
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Gjesing AP, Ribel-Madsen R, Harder MN, Eiberg H, Grarup N, Jørgensen T, Ekstrøm CT, Pedersen O, Hansen T. Genetic and phenotypic correlations between surrogate measures of insulin release obtained from OGTT data. Diabetologia 2015; 58:1006-12. [PMID: 25660259 DOI: 10.1007/s00125-015-3516-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Accepted: 01/12/2015] [Indexed: 10/24/2022]
Abstract
AIMS/HYPOTHESIS We examined the extent to which surrogate measures of insulin release have shared genetic causes. METHODS Genetic and phenotypic correlations were calculated in a family cohort (n = 315) in which beta cell indices were estimated based on fasting and oral glucose-stimulated plasma glucose, serum C-peptide and serum insulin levels. Furthermore, we genotyped a large population-based cohort (n = 6,269) for common genetic variants known to associate with type 2 diabetes, fasting plasma glucose levels or fasting serum insulin levels to examine their association with various indices. RESULTS We found a notable difference between the phenotypic and genetic correlations for the traits, emphasising that the phenotypic correlation is an insufficient measure of the magnitude of shared genetic impact. In addition, we found that corrected insulin response, insulinogenic index and incAUC for insulin after an oral glucose challenge shared the majority of their genetic backgrounds, with genetic correlations of 0.80-0.99. The BIGTT index for acute insulin response differed slightly more from the latter with genetic correlations of 0.78-0.87. The HOMA for beta cell function was genetically closely related to fasting insulin with a genetic correlation of 0.85. The effects of 82 selected susceptibility single nucleotide polymorphisms on these insulin secretion indices supported our interpretation of the data and added insight into the biological differences between the examined traits. CONCLUSIONS/INTERPRETATION The level of shared genetic background varies between surrogate measures of insulin release, and this should be considered when designing a genetic association study to best obtain information on various mechanisms of insulin release.
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Affiliation(s)
- Anette P Gjesing
- The Novo Nordisk Foundation Center for Basic Metabolic Research, Section of Metabolic Genetics, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 1-3, DK-2100, Copenhagen, Denmark,
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