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Liu Q, Han Y, Zhang M, Yang P, Xiang Y, Chen M, Xu F, Zhou X, Zheng D, Qin J. IGF1R stimulates autophagy, enhances viability, and promotes insulin secretion in pancreatic β cells in gestational diabetes mellitus by upregulating ATG7. Reprod Biol 2024; 24:100850. [PMID: 38262267 DOI: 10.1016/j.repbio.2023.100850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 12/20/2023] [Accepted: 12/26/2023] [Indexed: 01/25/2024]
Abstract
Gestational diabetes mellitus (GDM) is a prevalent metabolic disturbance in pregnancy. This article investigated the correlations between serum IGF1R and ATG7 with insulin resistance (IR) in GDM patients. Firstly, 100 GDM patients and 100 healthy pregnant women were selected as study subjects. The levels of serum IGF1, IGF1R, and ATG7 and their correlations with the insulin resistance index homeostasis model assessment of insulin resistance (HOMA-IR) were measured and analyzed by ELISA and Pearson. Additionally, in mouse pancreatic β cells, IGF1R, ATG7, Beclin-1, and LC3-II/LC3-I levels, cell viability/apoptosis, and insulin level were assessed by western blot, CCK-8, flow cytometry, and ELISA. The GDM group exhibited obviously raised serum IGF1 level and diminished serum IGF1R/ATG7 levels. The IGF1 level was positively correlated with HOMA-IR, while IGF1R/ATG7 levels were negatively correlated with HOMA-IR in GDM patients. Collectively, IGF1R stimulated cell viability, suppressed apoptosis, amplified insulin secretion, and increased ATG7 expression to induce cell autophagy, which could be partially averted by ATG7 silencing.
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Affiliation(s)
- Qing Liu
- Department of Maternity and Maternity Health, Guiyang Maternal and Child Health Care Hospital, Guiyang, China
| | - Ying Han
- Department of Maternity and Maternity Health, Guiyang Maternal and Child Health Care Hospital, Guiyang, China
| | - Meng Zhang
- Department of Maternity and Maternity Health, Guiyang Maternal and Child Health Care Hospital, Guiyang, China
| | - Peng Yang
- Department of Pediatric General Surgery, Guiyang Maternal and Child Health Care Hospital, Guiyang, China
| | - Yan Xiang
- Department of Maternity and Maternity Health, Guiyang Maternal and Child Health Care Hospital, Guiyang, China
| | - Min Chen
- Department of Maternity and Maternity Health, Guiyang Maternal and Child Health Care Hospital, Guiyang, China
| | - Fei Xu
- Department of Gynaecological Oncology, Guiyang Maternal and Child Health Care Hospital, Guiyang, China
| | - Xiaochan Zhou
- Department of Obstetrical, Guiyang Maternal and Child Health Care Hospital, Guiyang, China
| | - Dan Zheng
- Department of Maternity and Maternity Health, Guiyang Maternal and Child Health Care Hospital, Guiyang, China.
| | - Juan Qin
- Technology Management Center, Guiyang Maternal and Child Health Care Hospital, Guiyang, China.
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2
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Hu Q, Mu J, Liu Y, Yang Y, Liu Y, Pan Y, Zhang Y, Li L, Liu D, Chen J, Zhang F, Jin L. Obesity-Induced miR-455 Upregulation Promotes Adaptive Pancreatic β-Cell Proliferation Through the CPEB1/CDKN1B Pathway. Diabetes 2022; 71:394-411. [PMID: 35029277 DOI: 10.2337/db21-0134] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 12/13/2021] [Indexed: 11/13/2022]
Abstract
Pancreatic β-cells adapt to compensate for increased metabolic demand during obesity. Although the miRNA pathway has an essential role in β-cell expansion, whether it is involved in adaptive proliferation is largely unknown. First, we report that EGR2 binding to the miR-455 promoter induced miR-455 upregulation in the pancreatic islets of obesity mouse models. Then, in vitro gain- or loss-of-function studies showed that miR-455 overexpression facilitated β-cell proliferation. Knockdown of miR-455 in ob/ob mice via pancreatic intraductal infusion prevented compensatory β-cell expansion. Mechanistically, our results revealed that increased miR-455 expression inhibits the expression of its target cytoplasmic polyadenylation element binding protein 1 (CPEB1), an mRNA binding protein that plays an important role in regulating insulin resistance and cell proliferation. Decreased CPEB1 expression inhibits elongation of the poly(A) tail and the subsequent translation of Cdkn1b mRNA, reducing the CDKN1B expression level and finally promoting β-cell proliferation. Taken together, our results show that the miR-455/CPEB1/CDKN1B pathway contributes to adaptive proliferation of β-cells to meet metabolic demand during obesity.
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Affiliation(s)
- Qianxing Hu
- State Key Laboratory of Natural Medicines, Jiangsu Key Laboratory of Druggability of Biopharmaceuticals, School of Life Science and Technology, China Pharmaceutical University, Nanjing, Jiangsu Province, China
| | - Jinming Mu
- State Key Laboratory of Natural Medicines, Jiangsu Key Laboratory of Druggability of Biopharmaceuticals, School of Life Science and Technology, China Pharmaceutical University, Nanjing, Jiangsu Province, China
| | - Yuhong Liu
- State Key Laboratory of Natural Medicines, Jiangsu Key Laboratory of Druggability of Biopharmaceuticals, School of Life Science and Technology, China Pharmaceutical University, Nanjing, Jiangsu Province, China
| | - Yue Yang
- State Key Laboratory of Natural Medicines, Jiangsu Key Laboratory of Druggability of Biopharmaceuticals, School of Life Science and Technology, China Pharmaceutical University, Nanjing, Jiangsu Province, China
| | - Yue Liu
- State Key Laboratory of Natural Medicines, Jiangsu Key Laboratory of Druggability of Biopharmaceuticals, School of Life Science and Technology, China Pharmaceutical University, Nanjing, Jiangsu Province, China
| | - Yi Pan
- State Key Laboratory of Natural Medicines, Jiangsu Key Laboratory of Druggability of Biopharmaceuticals, School of Life Science and Technology, China Pharmaceutical University, Nanjing, Jiangsu Province, China
| | - Yanfeng Zhang
- State Key Laboratory of Natural Medicines, Jiangsu Key Laboratory of Druggability of Biopharmaceuticals, School of Life Science and Technology, China Pharmaceutical University, Nanjing, Jiangsu Province, China
| | - Ling Li
- Department of Endocrinology, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu Province, China
- Pancreatic Research Institute, Southeast University, Nanjing, Jiangsu Province, China
| | - Dechen Liu
- Department of Endocrinology, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu Province, China
| | - Jianqiu Chen
- College of Engineering, China Pharmaceutical University, Nanjing, Jiangsu Province, China
| | - Fangfang Zhang
- State Key Laboratory of Natural Medicines, Jiangsu Key Laboratory of Druggability of Biopharmaceuticals, School of Life Science and Technology, China Pharmaceutical University, Nanjing, Jiangsu Province, China
| | - Liang Jin
- State Key Laboratory of Natural Medicines, Jiangsu Key Laboratory of Druggability of Biopharmaceuticals, School of Life Science and Technology, China Pharmaceutical University, Nanjing, Jiangsu Province, China
- State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing, Jiangsu Province, China
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3
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Huang LA, Huang KX, Tu J, Kandeel F, Li J. Ramatroban-Based Analogues Containing Fluorine Group as Potential 18F-Labeled Positron Emission Tomography (PET) G-Protein Coupled Receptor 44 (GPR44) Tracers. Molecules 2021; 26:molecules26051433. [PMID: 33800801 PMCID: PMC7961607 DOI: 10.3390/molecules26051433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 03/03/2021] [Accepted: 03/04/2021] [Indexed: 11/16/2022] Open
Abstract
Diabetes remains one of the fastest growing chronic diseases and is a leading source of morbidity and accelerated mortality in the world. Loss of beta cell mass (BCM) and decreased sensitivity to insulin underlie diabetes pathogenesis. Yet, the ability to safely and directly assess BCM in individuals with diabetes does not exist. Measures such as blood glucose provide only a crude indirect picture of beta cell health. PET imaging could, in theory, allow for safe, direct, and precise characterization of BCM. However, identification of beta cell-specific radiolabeled tracers remains elusive. G-protein coupled receptor 44 (GPR44) is a transmembrane protein that was characterized in 2012 as highly beta cell-specific within the insulin-positive islets of Langerhans. Accordingly, radiolabeling of existing GPR44 antagonists could be a viable method to accelerate PET tracer development. The present study aims to evaluate and summarize published analogues of the GPR44 antagonist ramatroban to develop 18F-labeled PET tracers for BCM analysis. The 77 corresponding ramatroban analogues containing a fluorine nuclide were characterized for properties including binding affinity, selectivity, and pharmacokinetic and metabolic profile, and 32 compounds with favorable properties were identified. This review illustrates the potential of GPR44 analogues for the development of PET tracers.
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4
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Chittezhath M, Wai CMM, Tay VSY, Chua M, Langley SR, Ali Y. TLR4 signals through islet macrophages to alter cytokine secretion during diabetes. J Endocrinol 2020; 247:87. [PMID: 32755994 DOI: 10.1530/joe-20-0131] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Accepted: 08/04/2020] [Indexed: 11/08/2022]
Abstract
Toll-like receptors (TLRs), particularly TLR4, may act as immune sensors for metabolic stress signals such as lipids and link tissue metabolic changes to innate immunity. TLR signalling is not only tissue-dependent but also cell-type dependent and recent studies suggest that TLRs are not restricted to innate immune cells alone. Pancreatic islets, a hub of metabolic hormones and cytokines, respond to TLR signalling. However, the source of TLR signalling within the islet remain poorly understood. Uncovering the specific cell source and its role in mediating TLR signalling, especially within type 2 diabetes (T2D) islet will yield new targets to tackle islet inflammation, hormone secretion dysregulation and ultimately diabetes. In the present study, we immuno-characterised TLRs linked to pancreatic islets in both healthy and obese diabetic mice. We found that while TLRs1-4 and TLR9 were expressed in mouse islets, these TLRs did not co-localise with insulin-producing β-cells. β-Cells from obese diabetic mice were also devoid of these TLRs. While TLR immunoreactivity in obese mice islets increased, this was driven mostly by increased islet endothelial cell and islet macrophage presence. Analysis of human islet single-cell RNA-seq databases revealed that macrophages were an important source of islet TLRs. However, only TLR4 and TLR8 showed variation and cell-type specificity in their expression patterns. Cell depletion experiments in isolated mouse islets showed that TLR4 signalled through macrophages to alter islet cytokine secretome. Together, these studies suggest that islet macrophages are a dominant source of TLR4-mediated signalling in both healthy and diabetic islets.
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Affiliation(s)
- Manesh Chittezhath
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, Singapore, Singapore
| | - Cho M M Wai
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, Singapore, Singapore
| | - Vanessa S Y Tay
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, Singapore, Singapore
| | - Minni Chua
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, Singapore, Singapore
- Singapore Eye Research Institute (SERI), Singapore General Hospital, Singapore, Singapore
| | - Sarah R Langley
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, Singapore, Singapore
| | - Yusuf Ali
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, Singapore, Singapore
- Singapore Eye Research Institute (SERI), Singapore General Hospital, Singapore, Singapore
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5
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Martínez-Navarro I, Díaz-Molina R, Pulido-Capiz A, Mas-Oliva J, Luna-Reyes I, Rodríguez-Velázquez E, Rivero IA, Ramos-Ibarra MA, Alatorre-Meda M, García-González V. Lipid Modulation in the Formation of β-Sheet Structures. Implications for De Novo Design of Human Islet Amyloid Polypeptide and the Impact on β-Cell Homeostasis. Biomolecules 2020; 10:biom10091201. [PMID: 32824918 PMCID: PMC7563882 DOI: 10.3390/biom10091201] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 08/03/2020] [Accepted: 08/04/2020] [Indexed: 12/25/2022] Open
Abstract
Human islet amyloid polypeptide (hIAPP) corresponds to a 37-residue hormone present in insulin granules that maintains a high propensity to form β-sheet structures during co-secretion with insulin. Previously, employing a biomimetic approach, we proposed a panel of optimized IAPP sequences with only one residue substitution that shows the capability to reduce amyloidogenesis. Taking into account that specific membrane lipids have been considered as a key factor in the induction of cytotoxicity, in this study, following the same design strategy, we characterize the effect of a series of lipids upon several polypeptide domains that show the highest aggregation propensity. The characterization of the C-native segment of hIAPP (residues F23-Y37), together with novel variants F23R and I26A allowed us to demonstrate an effect upon the formation of β-sheet structures. Our results suggest that zwitterionic phospholipids promote adsorption of the C-native segments at the lipid-interface and β-sheet formation with the exception of the F23R variant. Moreover, the presence of cholesterol did not modify this behavior, and the β-sheet structural transitions were not registered when the N-terminal domain of hIAPP (K1-S20) was characterized. Considering that insulin granules are enriched in phosphatidylserine (PS), the property of lipid vesicles containing negatively charged lipids was also evaluated. We found that these types of lipids promote β-sheet conformational transitions in both the C-native segment and the new variants. Furthermore, these PS/peptides arrangements are internalized in Langerhans islet β-cells, localized in the endoplasmic reticulum, and trigger critical pathways such as unfolded protein response (UPR), affecting insulin secretion. Since this phenomenon was associated with the presence of cytotoxicity on Langerhans islet β-cells, it can be concluded that the anionic lipid environment and degree of solvation are critical conditions for the stability of segments with the propensity to form β-sheet structures, a situation that will eventually affect the structural characteristics and stability of IAPP within insulin granules, thus modifying the insulin secretion.
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Affiliation(s)
- Israel Martínez-Navarro
- Departamento de Bioquímica, Facultad de Medicina Mexicali, Universidad Autónoma de Baja California, Mexicali 21000, Baja California, Mexico; (I.M.-N.); (R.D.-M.); (A.P.-C.)
| | - Raúl Díaz-Molina
- Departamento de Bioquímica, Facultad de Medicina Mexicali, Universidad Autónoma de Baja California, Mexicali 21000, Baja California, Mexico; (I.M.-N.); (R.D.-M.); (A.P.-C.)
| | - Angel Pulido-Capiz
- Departamento de Bioquímica, Facultad de Medicina Mexicali, Universidad Autónoma de Baja California, Mexicali 21000, Baja California, Mexico; (I.M.-N.); (R.D.-M.); (A.P.-C.)
- Laboratorio de Biología Molecular, Facultad de Medicina Mexicali, Universidad Autónoma de Baja California, Mexicali 21000, Baja California, Mexico
| | - Jaime Mas-Oliva
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ciudad de Mexico 04510, Mexico; (J.M.-O.); (I.L.-R.)
| | - Ismael Luna-Reyes
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ciudad de Mexico 04510, Mexico; (J.M.-O.); (I.L.-R.)
| | - Eustolia Rodríguez-Velázquez
- Facultad de Odontología, Universidad Autónoma de Baja California, Tijuana 22390, Mexico;
- Tecnológico Nacional de México/I.T. Tijuana, Centro de Graduados e Investigación en Química-Grupo de Biomateriales y Nanomedicina, Tijuana 22510, Mexico
| | - Ignacio A. Rivero
- Tecnológico Nacional de México/Instituto Tecnológico de Tijuana, Centro de Graduados e Investigación en Química, Tijuana 22510, Baja California, Mexico;
| | - Marco A. Ramos-Ibarra
- Facultad de Ciencias Químicas e Ingeniería, Universidad Autónoma de Baja California, Tijuana 22390, Baja California, Mexico;
| | - Manuel Alatorre-Meda
- Cátedras CONACyT- Tecnológico Nacional de México/I.T. Tijuana, Centro de Graduados e Investigación en Química-Grupo de Biomateriales y Nanomedicina, Tijuana 22510, Mexico;
| | - Victor García-González
- Departamento de Bioquímica, Facultad de Medicina Mexicali, Universidad Autónoma de Baja California, Mexicali 21000, Baja California, Mexico; (I.M.-N.); (R.D.-M.); (A.P.-C.)
- Correspondence: ; Tel.: +52-68-6557-1622
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6
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Amouyal C, Castel J, Guay C, Lacombe A, Denom J, Migrenne-Li S, Rouault C, Marquet F, Georgiadou E, Stylianides T, Luquet S, Le Stunff H, Scharfmann R, Clément K, Rutter GA, Taboureau O, Magnan C, Regazzi R, Andreelli F. A surrogate of Roux-en-Y gastric bypass (the enterogastro anastomosis surgery) regulates multiple beta-cell pathways during resolution of diabetes in ob/ob mice. EBioMedicine 2020; 58:102895. [PMID: 32739864 PMCID: PMC7393530 DOI: 10.1016/j.ebiom.2020.102895] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 06/26/2020] [Accepted: 06/30/2020] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Bariatric surgery is an effective treatment for type 2 diabetes. Early post-surgical enhancement of insulin secretion is key for diabetes remission. The full complement of mechanisms responsible for improved pancreatic beta cell functionality after bariatric surgery is still unclear. Our aim was to identify pathways, evident in the islet transcriptome, that characterize the adaptive response to bariatric surgery independently of body weight changes. METHODS We performed entero-gastro-anastomosis (EGA) with pyloric ligature in leptin-deficient ob/ob mice as a surrogate of Roux-en-Y gastric bypass (RYGB) in humans. Multiple approaches such as determination of glucose tolerance, GLP-1 and insulin secretion, whole body insulin sensitivity, ex vivo glucose-stimulated insulin secretion (GSIS) and functional multicellular Ca2+-imaging, profiling of mRNA and of miRNA expression were utilized to identify significant biological processes involved in pancreatic islet recovery. FINDINGS EGA resolved diabetes, increased pancreatic insulin content and GSIS despite a persistent increase in fat mass, systemic and intra-islet inflammation, and lipotoxicity. Surgery differentially regulated 193 genes in the islet, most of which were involved in the regulation of glucose metabolism, insulin secretion, calcium signaling or beta cell viability, and these were normalized alongside changes in glucose metabolism, intracellular Ca2+ dynamics and the threshold for GSIS. Furthermore, 27 islet miRNAs were differentially regulated, four of them hubs in a miRNA-gene interaction network and four others part of a blood signature of diabetes resolution in ob/ob mice and in humans. INTERPRETATION Taken together, our data highlight novel miRNA-gene interactions in the pancreatic islet during the resolution of diabetes after bariatric surgery that form part of a blood signature of diabetes reversal. FUNDING European Union's Horizon 2020 research and innovation programme via the Innovative Medicines Initiative 2 Joint Undertaking (RHAPSODY), INSERM, Société Francophone du Diabète, Institut Benjamin Delessert, Wellcome Trust Investigator Award (212625/Z/18/Z), MRC Programme grants (MR/R022259/1, MR/J0003042/1, MR/L020149/1), Diabetes UK (BDA/11/0004210, BDA/15/0005275, BDA 16/0005485) project grants, National Science Foundation (310030-188447), Fondation de l'Avenir.
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Affiliation(s)
- Chloé Amouyal
- Sorbonne Université, INSERM, Nutrition and Obesities; Systemic approaches (NutriOmics), Paris, France; AP-HP, Pitié-Salpêtrière Hospital, Diabetology department, F-75013 Paris, France
| | - Julien Castel
- Université de Paris, BFA, UMR 8251, CNRS, F-75013 Paris, France
| | - Claudiane Guay
- Department of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, CH-1005, Lausanne, Switzerland
| | - Amélie Lacombe
- PreclinICAN, Institute of Cardiometabolism and Nutrition, Paris, France
| | - Jessica Denom
- Université de Paris, BFA, UMR 8251, CNRS, F-75013 Paris, France
| | | | - Christine Rouault
- Sorbonne Université, INSERM, Nutrition and Obesities; Systemic approaches (NutriOmics), Paris, France
| | - Florian Marquet
- Sorbonne Université, INSERM, Nutrition and Obesities; Systemic approaches (NutriOmics), Paris, France
| | - Eleni Georgiadou
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Imperial College London, London, UK
| | | | - Serge Luquet
- Université de Paris, BFA, UMR 8251, CNRS, F-75013 Paris, France
| | - Hervé Le Stunff
- Université de Paris, BFA, UMR 8251, CNRS, F-75013 Paris, France
| | - Raphael Scharfmann
- Université de Paris, Cochin Institute, Inserm U1016, Paris 75014, France
| | - Karine Clément
- Sorbonne Université, INSERM, Nutrition and Obesities; Systemic approaches (NutriOmics), Paris, France; APHP, Pitié-Salpêtrière Hospital, Nutrition department, F-75013 Paris, France
| | - Guy A Rutter
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Metabolism, Digestion and Reproduction, Imperial College London, London, UK; Lee Kong Chian School of Medicine, Nan Yang Technological University, Singapore
| | - Olivier Taboureau
- Université de Paris, BFA, Team CMPLI, Inserm U1133, CNRS UMR 8251, Paris, France
| | | | - Romano Regazzi
- Department of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, CH-1005, Lausanne, Switzerland; Department of Biomedical Sciences, University of Lausanne, Rue du Bugnon 7, CH-1005 Lausanne, Switzerland
| | - Fabrizio Andreelli
- Sorbonne Université, INSERM, Nutrition and Obesities; Systemic approaches (NutriOmics), Paris, France; AP-HP, Pitié-Salpêtrière Hospital, Diabetology department, F-75013 Paris, France.
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7
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Abstract
The polygenic background of selectively bred diabetes models mimics the etiology of type 2 diabetes. So far, three different rodent models (Goto-Kakizaki rats, Nagoya-Shibata-Yasuda mice, and Oikawa-Nagao mice) have been established in the diabetes research field by continuous selective breeding for glucose tolerance from outbred rodent stocks. The origin of hyperglycemia in these rodents is mainly insulin secretion deficiency from the pancreatic β-cells and mild insulin resistance in insulin target organs. In this chapter, we summarize backgrounds and phenotypes of these rodent models to highlight their importance in diabetes research. Then, we introduce experimental methodologies to evaluate β-cell exocytosis as a putative common defect observed in these rodent models.
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MESH Headings
- Animals
- Diabetes Mellitus, Experimental/etiology
- Diabetes Mellitus, Experimental/genetics
- Diabetes Mellitus, Experimental/metabolism
- Diabetes Mellitus, Type 1/etiology
- Diabetes Mellitus, Type 1/genetics
- Diabetes Mellitus, Type 1/metabolism
- Diabetes Mellitus, Type 2/etiology
- Diabetes Mellitus, Type 2/genetics
- Diabetes Mellitus, Type 2/metabolism
- Exocytosis
- Gene Expression Profiling/methods
- Glucose Intolerance
- Insulin Resistance/physiology
- Insulin Secretion/physiology
- Insulin-Secreting Cells/chemistry
- Insulin-Secreting Cells/cytology
- Insulin-Secreting Cells/metabolism
- Insulin-Secreting Cells/physiology
- Mice
- Mice, Inbred C3H
- Patch-Clamp Techniques/methods
- Phenotype
- Rats
- Rats, Wistar
- Selective Breeding/genetics
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Affiliation(s)
- Mototsugu Nagao
- Islet Cell Exocytosis, Lund University Diabetes Centre, Department of Clinical Sciences Malmö, Lund University, Malmö, Sweden.
- Clinical Research Centre, Skåne University Hospital, Lund and Malmö, Sweden.
- Department of Endocrinology, Diabetes and Metabolism, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan.
| | - Jonathan Lou S Esguerra
- Islet Cell Exocytosis, Lund University Diabetes Centre, Department of Clinical Sciences Malmö, Lund University, Malmö, Sweden
- Clinical Research Centre, Skåne University Hospital, Lund and Malmö, Sweden
| | - Anna Wendt
- Islet Cell Exocytosis, Lund University Diabetes Centre, Department of Clinical Sciences Malmö, Lund University, Malmö, Sweden
- Clinical Research Centre, Skåne University Hospital, Lund and Malmö, Sweden
| | - Akira Asai
- Department of Endocrinology, Diabetes and Metabolism, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan
- Food and Health Science Research Unit, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Hitoshi Sugihara
- Department of Endocrinology, Diabetes and Metabolism, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan
| | - Shinichi Oikawa
- Department of Endocrinology, Diabetes and Metabolism, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan
- Diabetes and Lifestyle-related Disease Center, Japan Anti-Tuberculosis Association, Fukujuji Hospital, Tokyo, Japan
| | - Lena Eliasson
- Islet Cell Exocytosis, Lund University Diabetes Centre, Department of Clinical Sciences Malmö, Lund University, Malmö, Sweden.
- Clinical Research Centre, Skåne University Hospital, Lund and Malmö, Sweden.
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8
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Malaiyandi LM, Sharthiya H, Barakat AN, Edwards JR, Dineley KE. Using FluoZin-3 and fura-2 to monitor acute accumulation of free intracellular Cd 2+ in a pancreatic beta cell line. Biometals 2019; 32:951-964. [PMID: 31754889 PMCID: PMC7446769 DOI: 10.1007/s10534-019-00226-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Accepted: 11/08/2019] [Indexed: 11/28/2022]
Abstract
The understanding of cellular Cd2+ accumulation and toxicity is hampered by a lack of fluorescent indicators selective for intracellular free Cd2+ ([Cd2+]i). In this study, we used depolarized MIN6 mouse pancreatic beta cells as a model for evaluating [Cd2+]i detection with commercially available fluorescent probes, most of which have been traditionally used to visualize [Ca2+]i and [Zn2+]i. We trialed a panel of 12 probes including fura-2, FluoZin-3, Leadmium Green, Rhod-5N, indo-1, Fluo-5N, and others. We found that the [Zn2+]i probe FluoZin-3 and the traditional [Ca2+]i probe fura-2 responded most consistently and robustly to [Cd2+]i accumulation mediated by voltage-gated calcium channels. While selective detection of [Cd2+]i by fura-2 required the omission of Ca2+ from extracellular buffers, FluoZin-3 responded to [Cd2+]i similarly in the presence or absence of extracellular Ca2+. Furthermore, we showed that FluoZin-3 and fura-2 can be used together for simultaneous monitoring of [Ca2+]i and [Cd2+]i in the same cells. None of the other fluorophores tested were effective [Cd2+]i detectors in this model.
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Affiliation(s)
- Latha M Malaiyandi
- Departments of Anatomy, College of Graduate Studies, Midwestern University, Downers Grove, IL, 60515, USA
| | - Harsh Sharthiya
- Departments of Anatomy, College of Graduate Studies, Midwestern University, Downers Grove, IL, 60515, USA
- AbbVie Inc., Headquarters 1 N. Waukegan Road, North Chicago, IL, 60064, USA
| | - Ameir N Barakat
- Departments of Anatomy, College of Graduate Studies, Midwestern University, Downers Grove, IL, 60515, USA
| | - Joshua R Edwards
- Departments of Pharmacology, College of Graduate Studies, Midwestern University, 555 31st Street, Downers Grove, IL, 60515, USA
| | - Kirk E Dineley
- Departments of Pharmacology, College of Graduate Studies, Midwestern University, 555 31st Street, Downers Grove, IL, 60515, USA.
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Kim MK, Shin HM, Jung H, Lee E, Kim TK, Kim TN, Kwon MJ, Lee SH, Rhee BD, Park JH. Comparison of pancreatic beta cells and alpha cells under hyperglycemia: Inverse coupling in pAkt-FoxO1. Diabetes Res Clin Pract 2017; 131:1-11. [PMID: 28666105 DOI: 10.1016/j.diabres.2017.05.017] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 05/04/2017] [Accepted: 05/16/2017] [Indexed: 01/09/2023]
Abstract
Type 2 diabetes manifests beta cell deficiencies and alpha cell expansion which is consistent with relative insulin deficiency and glucagon oversecretion. The effects of hyperglycemia on alpha cells are not as understood in comparison to beta cells. Hyperglycemia increases oxidative stress, which induces Akt activation or FoxO activation, depending on cell type. Several studies independently reported that FoxO1 translocations in alpha cells and beta cells were opposite. We compared the responses of pancreatic alpha cells and beta cells against hyperglycemia. Alpha TC-1 cells and Beta TC-6 cells were incubated with control (5mM Glucose) or high glucose (33mM Glucose) with or without PI3K inhibitor or FoxO1 inhibitor. We assessed PI3K, pAkt and phosphorylated FoxO1 (pFoxO1) in both cell lines. Immunostaining of BrdU and FoxO1 was detected by green fluorescence microscopy and confocal microscopy. Hyperglycemia and H2O2 decreased PI3K and pAKT in beta cells, but increased them in alpha cells. FoxO1 localizations and pFoxO1 expressions between alpha cells and beta cells were opposite. Proliferation of beta cells was decreased, but alpha cell proliferation was increased under hyperglycemia. Antioxidant enzymes including superoxide dismutase (SOD) and catalase were increased in beta cells and they were reversed with FoxO1 inhibitor treatment. Increased proliferation in alpha cells under hyperglycemia was attenuated with PI3K inhibitor. In conclusion, hyperglycemia increased alpha cell proliferation and glucagon contents which are opposite to beta cells. These differences may be related to contrasting PI3K/pAkt changes in both cells and subsequent FoxO1 modulation.
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Affiliation(s)
- Mi-Kyung Kim
- Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, Inje University, Busan, South Korea; Paik Institute for Clinical Research, Molecular Therapy Lab, Inje University, Busan, South Korea.
| | - Hyun Mi Shin
- Paik Institute for Clinical Research, Molecular Therapy Lab, Inje University, Busan, South Korea
| | - HyeSook Jung
- Paik Institute for Clinical Research, Molecular Therapy Lab, Inje University, Busan, South Korea
| | - EunJu Lee
- Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, Inje University, Busan, South Korea
| | - Tae Kyoon Kim
- Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, Inje University, Busan, South Korea
| | - Tae Nyun Kim
- Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, Inje University, Busan, South Korea
| | - Min Jeong Kwon
- Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, Inje University, Busan, South Korea
| | - Soon Hee Lee
- Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, Inje University, Busan, South Korea
| | - Byoung Doo Rhee
- Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, Inje University, Busan, South Korea
| | - Jeong Hyun Park
- Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, Inje University, Busan, South Korea; Paik Institute for Clinical Research, Molecular Therapy Lab, Inje University, Busan, South Korea
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10
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Palivec V, Viola CM, Kozak M, Ganderton TR, Křížková K, Turkenburg JP, Haluŝková P, Žáková L, Jiráĉek J, Jungwirth P, Brzozowski AM. Computational and structural evidence for neurotransmitter-mediated modulation of the oligomeric states of human insulin in storage granules. J Biol Chem 2017; 292:8342-8355. [PMID: 28348075 PMCID: PMC5437240 DOI: 10.1074/jbc.m117.775924] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 03/23/2017] [Indexed: 11/23/2022] Open
Abstract
Human insulin is a pivotal protein hormone controlling metabolism, growth, and aging and whose malfunctioning underlies diabetes, some cancers, and neurodegeneration. Despite its central position in human physiology, the in vivo oligomeric state and conformation of insulin in its storage granules in the pancreas are not known. In contrast, many in vitro structures of hexamers of this hormone are available and fall into three conformational states: T6, T3Rf3, and R6 As there is strong evidence for accumulation of neurotransmitters, such as serotonin and dopamine, in insulin storage granules in pancreatic β-cells, we probed by molecular dynamics (MD) and protein crystallography (PC) if these endogenous ligands affect and stabilize insulin oligomers. Parallel studies independently converged on the observation that serotonin binds well within the insulin hexamer (site I), stabilizing it in the T3R3 conformation. Both methods indicated serotonin binding on the hexamer surface (site III) as well. MD, but not PC, indicated that dopamine was also a good site III ligand. Some of the PC studies also included arginine, which may be abundant in insulin granules upon processing of pro-insulin, and stable T3R3 hexamers loaded with both serotonin and arginine were obtained. The MD and PC results were supported further by in solution spectroscopic studies with R-state-specific chromophore. Our results indicate that the T3R3 oligomer is a plausible insulin pancreatic storage form, resulting from its complex interplay with neurotransmitters, and pro-insulin processing products. These findings may have implications for clinical insulin formulations.
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Affiliation(s)
- Vladimír Palivec
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám 2, 166 10 Prague 6, Czech Republic
| | - Cristina M Viola
- York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Mateusz Kozak
- York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Timothy R Ganderton
- York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Květoslava Křížková
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám 2, 166 10 Prague 6, Czech Republic
| | - Johan P Turkenburg
- York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Petra Haluŝková
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám 2, 166 10 Prague 6, Czech Republic
| | - Lenka Žáková
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám 2, 166 10 Prague 6, Czech Republic
| | - Jiří Jiráĉek
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám 2, 166 10 Prague 6, Czech Republic.
| | - Pavel Jungwirth
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo nám 2, 166 10 Prague 6, Czech Republic.
| | - Andrzej M Brzozowski
- York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom.
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11
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Luo RQ, Wei F, Huang SS, Jiang YM, Zhang SL, Mo WQ, Liu H, Rong X. Real-Time, Label-Free Detection of Local Exocytosis Outside Pancreatic β Cells Using Laser Tweezers Raman Spectroscopy. Appl Spectrosc 2017; 71:422-431. [PMID: 27940997 DOI: 10.1177/0003702816670911] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The examination of insulin (Ins) exocytosis at the single-cell level by conventional methods, such as electrophysiological approaches, total internal reflection imaging, and two-photon imaging technology, often requires an invasive microelectrode puncture or label. In this study, high concentrations of glucose and potassium chloride were used to stimulate β cell Ins exocytosis, while low concentrations of glucose and calcium channel blockers served as the blank and negative control, respectively. Laser tweezers Raman spectroscopy (LTRS) was used to capture the possible Raman scattering signal from a local zone outside of the cell edge. The results show that the frequencies of the strong signals from the local zones outside the cellular edge in the stimulated groups are greater than those of the control. The Raman spectra from the cellular edge, Ins and cell membrane were compared. Thus, local Ins exocytosis activity outside pancreatic β cells might be observed indirectly using LTRS, a non-invasive optical method.
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Affiliation(s)
- Rui-Qiong Luo
- 1 Department of Geriatric Endocrinology, First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Fang Wei
- 1 Department of Geriatric Endocrinology, First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Shu-Shi Huang
- 2 The Laboratory of Biophysics, Guangxi Academy of Sciences, Nanning, China
| | - Yue-Ming Jiang
- 3 Department of Health Toxicology, School of Public Health, Guangxi Medical University, Nanning, China
| | - Shan-Lei Zhang
- 1 Department of Geriatric Endocrinology, First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Wen-Qing Mo
- 1 Department of Geriatric Endocrinology, First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Hong Liu
- 1 Department of Geriatric Endocrinology, First Affiliated Hospital of Guangxi Medical University, Nanning, China
| | - Xi Rong
- 1 Department of Geriatric Endocrinology, First Affiliated Hospital of Guangxi Medical University, Nanning, China
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12
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Cinti F, Bouchi R, Kim-Muller JY, Ohmura Y, Sandoval PR, Masini M, Marselli L, Suleiman M, Ratner LE, Marchetti P, Accili D. Evidence of β-Cell Dedifferentiation in Human Type 2 Diabetes. J Clin Endocrinol Metab 2016; 101:1044-54. [PMID: 26713822 PMCID: PMC4803182 DOI: 10.1210/jc.2015-2860] [Citation(s) in RCA: 368] [Impact Index Per Article: 46.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
CONTEXT Diabetes is associated with a deficit of insulin-producing β-cells. Animal studies show that β-cells become dedifferentiated in diabetes, reverting to a progenitor-like stage, and partly converting to other endocrine cell types. OBJECTIVE To determine whether similar processes occur in human type 2 diabetes, we surveyed pancreatic islets from 15 diabetic and 15 nondiabetic organ donors. DESIGN We scored dedifferentiation using markers of endocrine lineage, β-cell-specific transcription factors, and a newly identified endocrine progenitor cell marker, aldehyde dehydrogenase 1A3. RESULTS By these criteria, dedifferentiated cells accounted for 31.9% of β-cells in type 2 diabetics vs 8.7% in controls, and for 16.8% vs 6.5% of all endocrine cells (P < .001). The number of aldehyde dehydrogenase 1A3-positive/hormone-negative cells was 3-fold higher in diabetics compared with controls. Moreover, β-cell-specific transcription factors were ectopically found in glucagon- and somatostatin-producing cells of diabetic subjects. CONCLUSIONS The data support the view that pancreatic β-cells become dedifferentiated and convert to α- and δ-"like" cells in human type 2 diabetes. The findings should prompt a reassessment of goals in the prevention and treatment of β-cell dysfunction.
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Affiliation(s)
- Francesca Cinti
- Departments of Medicine (F.C., R.B., J.Y.K.-M., D.A.) and Surgery (Y.O., P.R.S., L.E.R.), Columbia University College of Physicians and Surgeons, New York, New York 10032; Department of Clinical and Experimental Medicine (F.C.), Università Politecnica delle Marche, Ancona, Italy; and Department of Clinical and Experimental Medicine (M.M., L.M., M.S., P.M.), Islet Cell Laboratory, University of Pisa, 56100 Pisa, Italy
| | - Ryotaro Bouchi
- Departments of Medicine (F.C., R.B., J.Y.K.-M., D.A.) and Surgery (Y.O., P.R.S., L.E.R.), Columbia University College of Physicians and Surgeons, New York, New York 10032; Department of Clinical and Experimental Medicine (F.C.), Università Politecnica delle Marche, Ancona, Italy; and Department of Clinical and Experimental Medicine (M.M., L.M., M.S., P.M.), Islet Cell Laboratory, University of Pisa, 56100 Pisa, Italy
| | - Ja Young Kim-Muller
- Departments of Medicine (F.C., R.B., J.Y.K.-M., D.A.) and Surgery (Y.O., P.R.S., L.E.R.), Columbia University College of Physicians and Surgeons, New York, New York 10032; Department of Clinical and Experimental Medicine (F.C.), Università Politecnica delle Marche, Ancona, Italy; and Department of Clinical and Experimental Medicine (M.M., L.M., M.S., P.M.), Islet Cell Laboratory, University of Pisa, 56100 Pisa, Italy
| | - Yoshiaki Ohmura
- Departments of Medicine (F.C., R.B., J.Y.K.-M., D.A.) and Surgery (Y.O., P.R.S., L.E.R.), Columbia University College of Physicians and Surgeons, New York, New York 10032; Department of Clinical and Experimental Medicine (F.C.), Università Politecnica delle Marche, Ancona, Italy; and Department of Clinical and Experimental Medicine (M.M., L.M., M.S., P.M.), Islet Cell Laboratory, University of Pisa, 56100 Pisa, Italy
| | - P R Sandoval
- Departments of Medicine (F.C., R.B., J.Y.K.-M., D.A.) and Surgery (Y.O., P.R.S., L.E.R.), Columbia University College of Physicians and Surgeons, New York, New York 10032; Department of Clinical and Experimental Medicine (F.C.), Università Politecnica delle Marche, Ancona, Italy; and Department of Clinical and Experimental Medicine (M.M., L.M., M.S., P.M.), Islet Cell Laboratory, University of Pisa, 56100 Pisa, Italy
| | - Matilde Masini
- Departments of Medicine (F.C., R.B., J.Y.K.-M., D.A.) and Surgery (Y.O., P.R.S., L.E.R.), Columbia University College of Physicians and Surgeons, New York, New York 10032; Department of Clinical and Experimental Medicine (F.C.), Università Politecnica delle Marche, Ancona, Italy; and Department of Clinical and Experimental Medicine (M.M., L.M., M.S., P.M.), Islet Cell Laboratory, University of Pisa, 56100 Pisa, Italy
| | - Lorella Marselli
- Departments of Medicine (F.C., R.B., J.Y.K.-M., D.A.) and Surgery (Y.O., P.R.S., L.E.R.), Columbia University College of Physicians and Surgeons, New York, New York 10032; Department of Clinical and Experimental Medicine (F.C.), Università Politecnica delle Marche, Ancona, Italy; and Department of Clinical and Experimental Medicine (M.M., L.M., M.S., P.M.), Islet Cell Laboratory, University of Pisa, 56100 Pisa, Italy
| | - Mara Suleiman
- Departments of Medicine (F.C., R.B., J.Y.K.-M., D.A.) and Surgery (Y.O., P.R.S., L.E.R.), Columbia University College of Physicians and Surgeons, New York, New York 10032; Department of Clinical and Experimental Medicine (F.C.), Università Politecnica delle Marche, Ancona, Italy; and Department of Clinical and Experimental Medicine (M.M., L.M., M.S., P.M.), Islet Cell Laboratory, University of Pisa, 56100 Pisa, Italy
| | - Lloyd E Ratner
- Departments of Medicine (F.C., R.B., J.Y.K.-M., D.A.) and Surgery (Y.O., P.R.S., L.E.R.), Columbia University College of Physicians and Surgeons, New York, New York 10032; Department of Clinical and Experimental Medicine (F.C.), Università Politecnica delle Marche, Ancona, Italy; and Department of Clinical and Experimental Medicine (M.M., L.M., M.S., P.M.), Islet Cell Laboratory, University of Pisa, 56100 Pisa, Italy
| | - Piero Marchetti
- Departments of Medicine (F.C., R.B., J.Y.K.-M., D.A.) and Surgery (Y.O., P.R.S., L.E.R.), Columbia University College of Physicians and Surgeons, New York, New York 10032; Department of Clinical and Experimental Medicine (F.C.), Università Politecnica delle Marche, Ancona, Italy; and Department of Clinical and Experimental Medicine (M.M., L.M., M.S., P.M.), Islet Cell Laboratory, University of Pisa, 56100 Pisa, Italy
| | - Domenico Accili
- Departments of Medicine (F.C., R.B., J.Y.K.-M., D.A.) and Surgery (Y.O., P.R.S., L.E.R.), Columbia University College of Physicians and Surgeons, New York, New York 10032; Department of Clinical and Experimental Medicine (F.C.), Università Politecnica delle Marche, Ancona, Italy; and Department of Clinical and Experimental Medicine (M.M., L.M., M.S., P.M.), Islet Cell Laboratory, University of Pisa, 56100 Pisa, Italy
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13
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Lampropoulou E, Lymperopoulou A, Charonis A. Reduced expression of ERp46 under diabetic conditions in β-cells and the effect of liraglutide. Metabolism 2016; 65:7-15. [PMID: 26683792 DOI: 10.1016/j.metabol.2015.09.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2015] [Revised: 09/11/2015] [Accepted: 09/12/2015] [Indexed: 10/23/2022]
Abstract
BACKGROUND Diabetes mellitus is characterized by peripheral insulin resistance, hyperglycemia and defective insulin secretion. Insulin producing pancreatic β-cells are equipped with a highly developed endoplasmic reticulum (ER) and thus are affected by ER stress under hyperglycemic conditions. We have previously studied the influence of high glucose on cultured β-cells in vitro. Proteomic analysis revealed a number of proteins involved in glucose toxicity, while further biochemical analysis identified the endoplasmic reticulum protein ERp46 as a molecule with a possible role in insulin production at the post-translational level. In addition, the involvement of incretin hormone glucagon-like peptide 1 (GLP-1) in diabetes proposes that incretin-mimetic compounds may be among the optimal choices in future therapeutic interventions; therefore their effects on various aspects of the pathogenesis of diabetes mellitus should be explored in detail. Based on the above, we examined the possible involvement of ERp46 in insulin production and the effect of the GLP-1 analogue liraglutide on the expression of ERp46 in vitro, in β-cells cultured under high glucose conditions and in vivo, in the mouse db/db diabetic model, where pronounced hyperglycemia is a key characteristic. RESULTS Confocal microscopy revealed areas of co-localization of ERp46 and pro-insulin in pancreatic islets. In order to explore the possible interaction between ERp46 and insulin immunoprecipitation was used. In extracts from cultured β-cells, antibodies against pro-insulin co-precipitated ERp46 and antibodies against ERp46 co-precipitated pro-insulin, as shown by Western blotting. Furthermore, data from a proximity ligation assay positioned these two molecules closer than 30nm in distance. When pancreatic β-cells were cultured in high glucose conditions they exhibited a decrease in ERp46 expression, while treatment with the GLP-1 analogue liraglutide restored ERp46 levels, leading to a significant increase of ERp46 in comparison to hyperglycemic conditions. In the diabetic mouse model db(-)/db, ERp46 expression was reduced in pancreatic islets, as documented by morphological and biochemical techniques. This decrease was abolished after treatment with the GLP-1 analogue in a dose-dependent manner. In an attempt to understand the underlying mechanism, we examined the sequence of the promoter of ERp46 and found consensus motifs that can be recognized by transcription factors ATF6 and XBP1. Subsequently, we performed chromatin immunoprecipitation assay and demonstrated that treatment of β-TC-6 cells with 25mmol/L glucose decreases gradually the binding enrichment of ATF6 and XBP1 in ERp46 gene promoter. CONCLUSIONS We propose that since ERp46 is a member of the disulfide isomerases family, it is likely to play a key role in insulin biosynthesis and its reduction under high glucose conditions may be a novel contributor to the glucotoxicity of β-cells. In addition, the GLP-1 analogue liraglutide seems to interfere in this process and may exert its beneficial effects in diabetes by affecting insulin production via restoration of ERp46 expression.
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Affiliation(s)
- Eugenia Lampropoulou
- Center for Clinical, Experimental Surgery and Translational Research, Biomedical Research Foundation of the Academy of Athens, Soranou Efessiou 4, Athens 115 27, Greece.
| | - Anna Lymperopoulou
- Center for Clinical, Experimental Surgery and Translational Research, Biomedical Research Foundation of the Academy of Athens, Soranou Efessiou 4, Athens 115 27, Greece.
| | - Aristidis Charonis
- Center for Clinical, Experimental Surgery and Translational Research, Biomedical Research Foundation of the Academy of Athens, Soranou Efessiou 4, Athens 115 27, Greece.
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14
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Buschard K, Bracey AW, McElroy DL, Magis AT, Osterbye T, Atkinson MA, Bailey KM, Posgai AL, Ostrov DA. Sulfatide Preserves Insulin Crystals Not by Being Integrated in the Lattice but by Stabilizing Their Surface. J Diabetes Res 2016; 2016:6179635. [PMID: 26981544 PMCID: PMC4769769 DOI: 10.1155/2016/6179635] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 01/14/2016] [Accepted: 01/14/2016] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Sulfatide is known to chaperone insulin crystallization within the pancreatic beta cell, but it is not known if this results from sulfatide being integrated inside the crystal structure or by binding the surface of the crystal. With this study, we aimed to characterize the molecular mechanisms underlying the integral role for sulfatide in stabilizing insulin crystals prior to exocytosis. METHODS We cocrystallized human insulin in the presence of sulfatide and solved the structure by molecular replacement. RESULTS The crystal structure of insulin crystallized in the presence of sulfatide does not reveal ordered occupancy representing sulfatide in the crystal lattice, suggesting that sulfatide does not permeate the crystal lattice but exerts its stabilizing effect by alternative interactions such as on the external surface of insulin crystals. CONCLUSIONS Sulfatide is known to stabilize insulin crystals, and we demonstrate here that in beta cells sulfatide is likely coating insulin crystals. However, there is no evidence for sulfatide to be built into the crystal lattice.
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Affiliation(s)
- Karsten Buschard
- Bartholin Instituttet, Rigshospitalet, 2100 Copenhagen, Denmark
- *Karsten Buschard:
| | - Austin W. Bracey
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida College of Medicine, 1600 SW Archer Road, Gainesville, FL 32610, USA
| | - Daniel L. McElroy
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida College of Medicine, 1600 SW Archer Road, Gainesville, FL 32610, USA
| | - Andrew T. Magis
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida College of Medicine, 1600 SW Archer Road, Gainesville, FL 32610, USA
| | - Thomas Osterbye
- Bartholin Instituttet, Rigshospitalet, 2100 Copenhagen, Denmark
| | - Mark A. Atkinson
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida College of Medicine, 1600 SW Archer Road, Gainesville, FL 32610, USA
| | - Kate M. Bailey
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida College of Medicine, 1600 SW Archer Road, Gainesville, FL 32610, USA
| | - Amanda L. Posgai
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida College of Medicine, 1600 SW Archer Road, Gainesville, FL 32610, USA
| | - David A. Ostrov
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida College of Medicine, 1600 SW Archer Road, Gainesville, FL 32610, USA
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15
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Abstract
INTRODUCTION Islet transplantation can treat the most severe cases of type 1 diabetes but it currently requires deceased donor pancreata as an islet source and chronic immunosuppression to prevent rejection and recurrence of autoimmunity. Stem cell-derived insulin-producing cells may address the shortage of organ donors, whereas cell encapsulation may reduce or eliminate the requirement for immunosuppression, minimizing the risks associated with the islet transplantation procedure, and potentially prolonging graft survival. AREAS COVERED This review focuses on the design principles for immunoisolation devices and on stem cell differentiation into insulin-producing cell products. The reader will gain understanding of the different types of immunoisolation devices and the key parameters that affect the outcome of the encapsulated graft. Progresses in stem cell differentiation towards mature endocrine islet cells, including the most recent clinical trials and the challenges associated with the application of immunoisolation devices designed for primary islets to stem-cell products, are also discussed. EXPERT OPINION Recent advancements in the field of stem cell-derived islet cell products and immunoisolation strategies hold great promise for type 1 diabetes. However, a combination product including both cells and an immunoisolation strategy still needs to be optimized and tested for safety and efficacy.
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Affiliation(s)
- Alice Anna Tomei
- University of Miami Miller School of Medicine, Diabetes Research Institute , 1450 NW 10th Avenue, Miami, FL 33136 , USA +1 305 243 3469 ;
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16
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Zhou QL, Rong X, Wei F, Luo RQ, Liu H. Different Raman spectral patterns of primary rat pancreatic β cells and insulinoma cells. J Biomed Opt 2015; 20:047001. [PMID: 25848805 DOI: 10.1117/1.jbo.20.4.047001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2015] [Accepted: 03/17/2015] [Indexed: 06/04/2023]
Abstract
As a noninvasive and label-free analytical technique, Raman spectroscopy has been widely used to study the difference between malignant cells and normal cells. Insulinomas are functional β-cell tumors of pancreatic islet cells. They exhibit many structural and immunohistochemical features in common with normal pancreatic β cells; thus, they are typically difficult to distinguish under the microscope, especially in vivo. We investigated insulinoma and primary rat pancreatic β-cell populations using Raman spectroscopy. The details of the optical heterogeneity between these two populations were determined based on different Raman regions primarily involving nucleic acid and protein contents, which are the most distinct cellular contents in these two types of cells. Using principal component analysis–linear discriminant analysis, these two cell types can be readily separated. The results of this work indicate that Raman spectroscopy is a promising tool for the noninvasive and label-free differentiation of insulinoma cells and normal pancreatic β cells.
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Affiliation(s)
- Qiu-Li Zhou
- Guangxi Medical University, No. 22 Shuangyong Road, Nanning 530021, China
| | - Xi Rong
- First Affiliated Hospital of Guangxi Medical University, Department of Geriatric Endocrinology, No. 6 Shuangyong Road, Nanning 530021, China
| | - Fang Wei
- Guangxi Medical University, No. 22 Shuangyong Road, Nanning 530021, China
| | - Rui-Qiong Luo
- Guangxi Medical University, No. 22 Shuangyong Road, Nanning 530021, China
| | - Hong Liu
- First Affiliated Hospital of Guangxi Medical University, Department of Geriatric Endocrinology, No. 6 Shuangyong Road, Nanning 530021, China
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17
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Abstract
The loss of or decreased functional pancreatic β-cell is a major cause of type 1 and type 2 diabetes. Previous studies have shown that adult β-cells can maintain their ability for a low level of turnover through replication and neogenesis. Thus, a strategy to prevent and treat diabetes would be to enhance the ability of β-cells to increase the mass of functional β-cells. Consequently, much effort has been devoted to identify factors that can effectively induce β-cell expansion. This review focuses on recent reports on small molecules and protein factors that have been shown to promote β-cell expansion.
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Affiliation(s)
- Qiu Li
- Shandong Provincial Hospital Affiliated to Shandong University, Jinan, 250021 China
| | - Zhi-Chun Lai
- Shandong Provincial Hospital Affiliated to Shandong University, Jinan, 250021 China
- Department of Biology, The Pennsylvania State University, University Park, PA 16802 USA
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802 USA
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18
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Rajagopal A, Kulkarni S, Lewis KT, Chen X, Maarouf A, Kelly CV, Taatjes DJ, Jena BP. Proteome of the insulin-secreting Min6 cell porosome complex: involvement of Hsp90 in its assembly and function. J Proteomics 2014; 114:83-92. [PMID: 25464371 DOI: 10.1016/j.jprot.2014.11.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 10/19/2014] [Accepted: 11/03/2014] [Indexed: 11/15/2022]
Abstract
UNLABELLED Porosomes are secretory portals located at the cell plasma membrane involved in the regulated release of intravesicular contents from cells. Porosomes have been immunoisolated from a number of cells including the exocrine pancreas and neurons, biochemically characterized, and functionally reconstituted into an artificial lipid membrane. In the current study, the proteome of the porosome complex in mouse insulinoma Min6 cells was determined, demonstrating among other proteins, the presence of 30 core proteins including the heat shock protein Hsp90. Half maximal inhibition of Hsp90 using the specific inhibitor 17-demethoxy-17-(2-prophenylamino) geldanamycin, results in the loss of proteins, including the calcium-transporting ATPase type 2C and the potassium channel subfamily K member 2 from the Min6 porosome. This loss of porosome proteins is reflected in the observed inhibition of glucose stimulated insulin release from Min6 cells exposed to the Hsp90 specific inhibitor. Results from the study implicate Hsp90 in the assembly and function of the porosome complex. BIOLOGICAL SIGNIFICANCE In the present study, the porosome proteome in the insulin-secreting mouse β-cell line Min6 has been determined. Nearly 30 core proteins including the heat shock protein Hsp90 are found to compose the Min6 porosome complex. Results from the study implicate Hsp90 in the assembly of the Min6 porosome. These new findings will facilitate understanding of the porosome assembly and its function in insulin secretion.
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Affiliation(s)
- Amulya Rajagopal
- Wayne State University School of Medicine, Department of Physiology, Detroit, MI, USA
| | - Sanjana Kulkarni
- Wayne State University School of Medicine, Department of Physiology, Detroit, MI, USA
| | - Kenneth T Lewis
- Wayne State University School of Medicine, Department of Physiology, Detroit, MI, USA
| | - Xuequn Chen
- Wayne State University School of Medicine, Department of Physiology, Detroit, MI, USA
| | - Abir Maarouf
- Wayne State University, Department of Physics and Astronomy, Detroit, MI, USA
| | - Christopher V Kelly
- Wayne State University, Department of Physics and Astronomy, Detroit, MI, USA
| | - Douglas J Taatjes
- Department of Pathology and Laboratory Medicine, Microscopy Imaging Center, University of Vermont College of Medicine, Burlington, VT 05405, USA
| | - Bhanu P Jena
- Wayne State University School of Medicine, Department of Physiology, Detroit, MI, USA; Wayne State University, Department of Physics and Astronomy, Detroit, MI, USA.
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19
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Abstract
High levels of aldehyde dehydrogenase (ALDH) activity have been regarded as a specific feature of progenitor cells and stem cells. Hence, as an indicator of ALDH activity, aldefluor fluorescence has been widely used for the identification and isolation of stem and progenitor cells. ALDH activity was recently detected in embryonic mouse pancreas, and specifically and exclusively in adult centroacinar and terminal duct cells, suggesting that these duct cells may harbor cells of endocrine and exocrine differentiation potential in the adult pancreas. Here, we report the presence of aldefluor+ beta-cells in a beta-cell proliferation model, partial pancreatectomy. The aldefluor+ beta-cells are essentially all positive for Ki-67 and expressed high levels of cell-cycle activators such as CyclinD1, CyclinD2, and CDK4, suggesting that they are mitotic cells. Our data thus reveal a potential change in ALDH activity of proliferating beta-cells, which provides a novel method for the isolation and analysis of proliferating beta-cells. Moreover, our data also suggest that aldefluor lineage-tracing is not a proper method for analyzing progenitor or stem activity in the adult pancreas.
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Affiliation(s)
- Yinglan Liu
- Department of Endocrinology, The First Affiliated Hospital of Nanhua University, No. 69 Chuanshan Road, Hengyang, 421001, Hunan Province, China
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20
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Tamagno G, Vigolo S, Olivieri M, Martini C, De Carlo E. From the rat to the beta cell: a fast and effective technique of separation of Langerhans islets and direct purification of pancreatic beta cells. Endocr Res 2014; 39:18-21. [PMID: 23789587 DOI: 10.3109/07435800.2013.797430] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Isolated Langerhans islets represent a useful model for the study of the endocrine pancreas. The possibility to purify pancreatic beta cells from a mixed Langerhans islet cell population may lead towards a dedicated focus on beta cell research. We describe an effective and rapid immunomagnetic technique for the direct purification of beta cells from isolated Langerhans islets of rat. After the sacrifice of the rat, the Langerhans islets were separated by ductal injection of the pancreas with collagenase, altered to a mixed Langerhans islet cell population and incubated with conditioned immunomagnetic beads targeted to the beta cell surface. The beads were previously coated with a specific antibody against the surface of the beta cell, namely K14D10. The suspension of mixed Langerhans islet cells and immunomagnetic K14D10-conditioned beads was pelleted by a magnetic particle concentrator to isolate the bead-bound cells, which were finally suspended in a culture medium. The purified cells were immunoreactive for insulin and no glucagon-positive cells were detected at immunocytochemistry. Real Time PCR confirmed the purification of the pancreatic beta cells. This immunomagnetic technique allows a rapid, effective and consistent purification of beta cells from isolated Langerhans islets in a direct manner by conditioning the immunomagnetic beads only. This technique is easy, fast and reproducible. It promises to be a reliable method for providing purified beta cells for in vitro research.
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Affiliation(s)
- Gianluca Tamagno
- Department of Endocrinology and Diabetes Mellitus, St Vincent's University Hospital, University College Dublin , Ireland and
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21
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Tapia-Limonchi R, Díaz I, Cahuana GM, Bautista M, Martín F, Soria B, Tejedo JR, Bedoya FJ. Impact of exposure to low concentrations of nitric oxide on protein profile in murine and human pancreatic islet cells. Islets 2014; 6:e995997. [PMID: 25658244 PMCID: PMC4398281 DOI: 10.1080/19382014.2014.995997] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Homeostatic levels of nitric oxide (NO) protect efficiently against apoptotic death in both human and rodent pancreatic β cells, but the protein profile of this action remains to be determined. We have applied a 2 dimensional LC-MS-MALDI-TOF/TOF-based analysis to study the impact of protective NO in rat insulin-producing RINm5F cell line and in mouse and human pancreatic islets (HPI) exposed to serum deprivation condition. 24 proteins in RINm5F and 22 in HPI were identified to undergo changes in at least one experimental condition. These include stress response mitochondrial proteins (UQCRC2, VDAC1, ATP5C1, ATP5A1) in RINm5F cells and stress response endoplasmic reticulum proteins (HSPA5, PDIA6, VCP, GANAB) in HPI. In addition, metabolic and structural proteins, oxidoreductases and chaperones related with protein metabolism are also regulated by NO treatment. Network analysis of differentially expressed proteins shows their interaction in glucocorticoid receptor and NRF2-mediated oxidative stress response pathways and eNOS signaling. The results indicate that exposure to exogenous NO counteracts the impact of serum deprivation on pancreatic β cell proteome. Species differences in the proteins involved are apparent.
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Affiliation(s)
- Rafael Tapia-Limonchi
- Andalusian Center for Molecular Biology and
Regenerative Medicine (CABIMER)- Pablo de Olavide University; Biomedical Research
Network (CIBER) of Diabetes and Related Metabolic Diseases; RED-TERCEL;
Seville, Spain
| | - Irene Díaz
- Andalusian Center for Molecular Biology and
Regenerative Medicine (CABIMER)- Pablo de Olavide University; Biomedical Research
Network (CIBER) of Diabetes and Related Metabolic Diseases; RED-TERCEL;
Seville, Spain
| | - Gladys M Cahuana
- Andalusian Center for Molecular Biology and
Regenerative Medicine (CABIMER)- Pablo de Olavide University; Biomedical Research
Network (CIBER) of Diabetes and Related Metabolic Diseases; RED-TERCEL;
Seville, Spain
| | - Mario Bautista
- Andalusian Center for Molecular Biology and
Regenerative Medicine (CABIMER)- Pablo de Olavide University; Biomedical Research
Network (CIBER) of Diabetes and Related Metabolic Diseases; RED-TERCEL;
Seville, Spain
| | - Franz Martín
- Andalusian Center for Molecular Biology and
Regenerative Medicine (CABIMER)- Pablo de Olavide University; Biomedical Research
Network (CIBER) of Diabetes and Related Metabolic Diseases; RED-TERCEL;
Seville, Spain
| | - Bernat Soria
- Andalusian Center for Molecular Biology and
Regenerative Medicine (CABIMER)-Fundación Progreso y Salud; Biomedical Research
Network (CIBER) of Diabetes and Related Metabolic Diseases; RED-TERCEL;
Seville, Spain
| | - Juan R Tejedo
- Andalusian Center for Molecular Biology and
Regenerative Medicine (CABIMER)- Pablo de Olavide University; Biomedical Research
Network (CIBER) of Diabetes and Related Metabolic Diseases; RED-TERCEL;
Seville, Spain
| | - Francisco J Bedoya
- Andalusian Center for Molecular Biology and
Regenerative Medicine (CABIMER)- Pablo de Olavide University; Biomedical Research
Network (CIBER) of Diabetes and Related Metabolic Diseases; RED-TERCEL;
Seville, Spain
- Correspondence to: Francisco J. Bedoya;
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22
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Lee YS, Kobayashi M, Kikuchi O, Sasaki T, Yokota-Hashimoto H, Susanti VY, Ido Kitamura Y, Kitamura T. ATF3 expression is induced by low glucose in pancreatic α and β cells and regulates glucagon but not insulin gene transcription. Endocr J 2014; 61:85-90. [PMID: 24140652 DOI: 10.1507/endocrj.ej13-0383] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The pancreas is critical for maintaining glucose homeostasis. Activating transcription factor 3 (ATF3) is an adaptive response transcription factor. There are major discrepancies in previous reports on pancreatic ATF3; therefore, its role in the pancreas is unclear. To better elucidate the role of ATF3 in the pancreas, we conducted in vitro studies using pancreatic α and β cell lines, and also evaluated the use of ATF3 antibodies for immunohistochemistry. We determined ATF3 expression was increased by low glucose and decreased by high glucose in both αTC-1.6 and βTC3 cells. We also showed that adenovirus-mediated ATF3 overexpression increased glucagon promoter activity and glucagon mRNA levels in αTC-1.6 cells; whereas, it had no effect on insulin promoter activity and insulin mRNA levels in βTC3 cells. Although immunostaining with the C-19 ATF3 antibody demonstrated predominant expression in α cells rather than β cells, ATF3 staining was still detected in ATF3 knockout mice as clearly as in control mice. On the other hand, another ATF3 antibody (H-90) detected ATF3 in both α cells and β cells, and was clearly diminished in ATF3 knockout mice. These results indicate that previous discrepancies in ATF3 expression patterns in the pancreas were caused by the varying specificities of the ATF3 antibodies used, and that ATF3 is actually expressed in both α cells and β cells.
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Affiliation(s)
- Yong-Soo Lee
- Metabolic Signal Research Center, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Gunma, Japan
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23
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Syed SK, Kauffman AL, Beavers LS, Alston JT, Farb TB, Ficorilli J, Marcelo MC, Brenner MB, Bokvist K, Barrett DG, Efanov AM. Ectonucleotidase NTPDase3 is abundant in pancreatic β-cells and regulates glucose-induced insulin secretion. Am J Physiol Endocrinol Metab 2013; 305:E1319-26. [PMID: 24085034 DOI: 10.1152/ajpendo.00328.2013] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Extracellular ATP released from pancreatic β-cells acts as a potent insulinotropic agent through activation of P2 purinergic receptors. Ectonucleotidases, a family of membrane-bound nucleotide-metabolizing enzymes, regulate extracellular ATP levels by degrading ATP and related nucleotides. Ectonucleotidase activity affects the relative proportion of ATP and its metabolites, which in turn will impact the level of purinergic receptor stimulation exerted by extracellular ATP. Therefore, we investigated the expression and role of ectonucleotidases in pancreatic β-cells. Of the ectonucleotidases studied, only ENTPD3 (gene encoding the NTPDase3 enzyme) mRNA was detected at fairly abundant levels in human and mouse pancreatic islets as well as in insulin-secreting MIN6 cells. ARL67156, a selective ectonucleotidase inhibitor, blocked degradation of extracellular ATP that was added to MIN6 cells. The compound also decreased degradation of endogenous ATP released from cells. Measurements of insulin secretion in MIN6 cells as well as in mouse and human pancreatic islets demonstrated that ARL67156 potentiated glucose-dependent insulin secretion. Downregulation of NTPDase3 expression in MIN6 cells with the specific siRNA replicated the effects of ARL67156 on extracellular ATP hydrolysis and insulin secretion. Our results demonstrate that NTPDase3 is the major ectonucleotidase in pancreatic β-cells in multiple species and that it modulates insulin secretion by controlling activation of purinergic receptors.
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Affiliation(s)
- Samreen K Syed
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana
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24
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Xie H, Wang Y, Zhang H, Qi H, Zhou H, Li FR. Role of injured pancreatic extract promotes bone marrow-derived mesenchymal stem cells efficiently differentiate into insulin-producing cells. PLoS One 2013; 8:e76056. [PMID: 24058711 PMCID: PMC3776851 DOI: 10.1371/journal.pone.0076056] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Accepted: 08/24/2013] [Indexed: 12/22/2022] Open
Abstract
Mesenchymal stem cells (MSCs) can be successfully induced to differentiate into insulin-producing cells (IPCs) by a variety of small molecules and cytokines in vitro. However, problems remain, such as low transdifferentiation efficiency and poor maturity of trans-differentiated cells. The damaged pancreatic cells secreted a large amount of soluble proteins, which were able to promote pancreative islet regeneration and MSCs differentiation. In this study, we utilized the rat injured pancreatic tissue extract to modulate rat bone marrow-derived MSCs differentiation into IPCs by the traditional two-step induction. Our results showed that injured pancreatic tissue extract could effectively promote the trans-differentiation efficiency and maturity of IPCs by the traditional induction. Moreover, IPCs were able to release more insulin in a glucose-dependent manner and ameliorate better the diabetic conditions of streptozotocin (STZ)-treated rats. Our study provides a new strategy to induce an efficient and directional differentiation of MSCs into IPCs.
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Affiliation(s)
- Hongbin Xie
- The Key Laboratory of stem cell and cellular therapy, the Second Clinical Medical College (Shenzhen People’s Hospital), Jinan University, Shenzhen, China
| | - Yunshuai Wang
- The Key Laboratory of stem cell and cellular therapy, the Second Clinical Medical College (Shenzhen People’s Hospital), Jinan University, Shenzhen, China
| | - Hui Zhang
- Laboratory of Cancer Cell Proteomics, Nevada Cancer Institute, Las Vegas, Nevada, United States of America
| | - Hui Qi
- The Key Laboratory of stem cell and cellular therapy, the Second Clinical Medical College (Shenzhen People’s Hospital), Jinan University, Shenzhen, China
| | - Hanxin Zhou
- Department of General Surgery, First Hospital (Shenzhen second People’s Hospital) of Shenzhen University, Shenzhen, China
| | - Fu-Rong Li
- The Key Laboratory of stem cell and cellular therapy, the Second Clinical Medical College (Shenzhen People’s Hospital), Jinan University, Shenzhen, China
- Shenzhen Institute of Gerontology, Shenzhen, China
- * E-mail:
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25
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van Genderen FT, Gorus FK, Pipeleers DG, van Schravendijk CFH. Sensitive and specific time-resolved fluorescence immunoassay of rat C-peptide for measuring hormone secretory and storage capacity of β-cells in vivo and in vitro. Endocrinology 2013; 154:1934-9. [PMID: 23525244 DOI: 10.1210/en.2012-2167] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The limitations of current rat C-peptide assays led us to develop a time-resolved fluorescence immunoassay for measurements in plasma, incubation media, and tissue/cell extracts. The assay uses 2 monoclonal antibodies, binding to different parts of the C-peptide molecule, and allowing, respectively, capture of the peptide and its detection by europium-labeled streptavidin. It is performed on 25-μL samples for a dynamic range from 66pM up to 3900pM C-peptide and displays over 95% recovery of added peptide in the range of 111pM to 2786pM. Its inter- and intra-assay coefficients of variations are, respectively, lower than 7.6% and 4.8%. Cross-reactivities by rat insulin and by human and porcine C-peptide are negligible, and cross-reactivity by mouse C-peptide is 6% ± 2%. The assay has been validated for in vivo and in vitro measurements of C-peptide release and cellular content. Release patterns were similar to those for insulin and occurred in equimolar concentrations for both peptides. The molar C-peptide contents in purified β-cells and isolated islets were similar to the corresponding insulin contents. This was also the case for pancreatic extracts containing protease inhibitors.
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Affiliation(s)
- Farah T van Genderen
- Department of Clinical Biology of Diabetes, Brussels University Hospital (UZ-Brussel), 101 Laarbeeklaan, B-1090 Brussels, Belgium.
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26
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Russo L, Marsella C, Nardo G, Massignan T, Alessio M, Piermarini E, La Rosa S, Finzi G, Bonetto V, Bertuzzi F, Maechler P, Massa O. Transglutaminase 2 transamidation activity during first-phase insulin secretion: natural substrates in INS-1E. Acta Diabetol 2013; 50:61-72. [PMID: 22382775 DOI: 10.1007/s00592-012-0381-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2012] [Accepted: 02/08/2012] [Indexed: 11/28/2022]
Abstract
Transglutaminase 2 (TG2) is a multifunctional protein with Ca(2+)-dependent transamidating and G protein activity. Previously, we reported that tgm2 -/- mice have an impaired insulin secretion and that naturally occurring TG2 mutations associated with familial, early-onset type 2 diabetes, show a defective transamidating activity. Aim of this study was to get a better insight into the role of TG2 in insulin secretion by identifying substrates of TG2 transamidating activity in the pancreatic beta cell line INS-1E. To this end, we labeled INS-1E that are capable of secreting insulin upon glucose stimulation in the physiologic range, with an artificial acyl acceptor (biotinamido-pentylamine) or donor (biotinylated peptide), in basal condition and after stimulus with glucose for 2, 5, and 8 min. Biotinylated proteins were analyzed by two-dimensional electrophoresis and mass spectrometry. In addition, subcellular localization of TG2 in human endocrine pancreas was studied by electron microscopy. Among several TG2's transamidating substrates in INS-1E, mass spectrometry identified cytoplasmic actin (a result confirmed in human pancreatic islet), tropomyosin, and molecules that participate in insulin granule structure (e.g., GAPDH), glucose metabolism, or [Ca(2+)] sensing (e.g., calreticulin). Physical interaction between TG2 and cytoplasmic actin during glucose-stimulated first-phase insulin secretion was confirmed by co-immunoprecipitation. Electron microscopy revealed that TG2 is localized close to insulin and glucagon granules in human pancreatic islet. We propose that TG2's role in insulin secretion may involve cytoplasmic actin remodeling and may have a regulative action on other proteins during granule movement. A similar role of TG2 in glucagon secretion is also suggested.
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Affiliation(s)
- Lucia Russo
- Laboratory of Mendelian Diabetes, Bambino Gesù Children's Hospital, Research Institute, Rome, Italy
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27
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Whitlock KA, Kozicky L, Jin A, Yee H, Ha C, Morris J, Field CJ, Bell RC, Ozga JA, Chan CB. Assessment of the mechanisms exerting glucose-lowering effects of dried peas in glucose-intolerant rats. Br J Nutr 2012; 108 Suppl 1:S91-102. [PMID: 22916820 DOI: 10.1017/s0007114512000736] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The present study compared the effects of feeding uncooked pea fractions (embryo v. seed coat) on glucose homeostasis in glucose-intolerant rats and examined potential mechanisms influencing glucose homeostasis. Rats were made glucose intolerant by high-fat feeding, after which diets containing both high-fat and pea fractions were fed for 4 weeks. Rats fed diets containing uncooked pea seed coats low (non-coloured seed coat; NSC) or high (coloured seed coat; CSC) in proanthocyanidins but not embryos had improved oral glucose tolerance (P < 0·05). NSC also lowered fasting and glucose-stimulated insulin secretion (P < 0·05), decreased β-cell mass by 50 % (P < 0·05) and lowered levels of malondialdehyde, a marker of oxidative stress. Furthermore, NSC decreased the mucosal thickness of the colon by 25 % (P < 0·05), which might affect fibre fermentation and other gut functions. Small but statistically significant (P < 0·05) effects consistent with enhanced glucose transport or metabolism were observed in the skeletal muscle of rats fed NSC or CSC, for example, increased levels of AMP-dependent kinase or akt. We conclude that pea seed coats are the fraction exerting beneficial effects on glucose tolerance. Most of the changes were small in amplitude, suggesting that additive effects on multiple tissues may be important. NSC content appeared to have the most beneficial effects in improving glucose homeostasis but our ability to detect the effect of flavonoids may have been limited by their low concentration in the diet.
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Affiliation(s)
- Kevin A Whitlock
- Department of Physiology, University of Alberta, Edmonton, Alberta, Canada T6G 2R3
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28
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Payeur AL, Lorenz MA, Kennedy RT. Analysis of fatty acid composition in insulin secreting cells by comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry. J Chromatogr B Analyt Technol Biomed Life Sci 2012; 893-894:187-92. [PMID: 22456534 PMCID: PMC3322247 DOI: 10.1016/j.jchromb.2012.03.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Revised: 02/28/2012] [Accepted: 03/01/2012] [Indexed: 11/28/2022]
Abstract
A comprehensive two-dimensional gas chromatography (GC×GC) time-of-flight mass spectrometry method was developed for determination of fatty acids (irrespective of origin, i.e., both free fatty acids and fatty acids bound in sources such as triglycerides) in cultured mammalian cells. The method was applied to INS-1 cells, an insulin-secreting cell line commonly used as a model in diabetes studies. In the method, lipids were extracted and transformed to fatty acid methyl esters for analysis. GC×GC analysis revealed the presence of 30 identifiable fatty acids in the extract. This result doubles the number of fatty acids previously identified in these cells. The method yielded linear calibrations and an average relative standard deviation of 8.4% for replicate injections of samples and 12.4% for replicate analysis of different samples. The method was used to demonstrate changes in fatty acid content as a function of glucose concentration on the cells. These results demonstrate the utility of this method for analysis of fatty acids in mammalian cell cultures.
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Affiliation(s)
- Amy L. Payeur
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Matthew A. Lorenz
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
| | - Robert T. Kennedy
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109, USA
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29
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Kapur R, Højfeldt TW, Højfeldt TW, Rønn SG, Karlsen AE, Heller RS. Short-term effects of INGAP and Reg family peptides on the appearance of small β-cells clusters in non-diabetic mice. Islets 2012; 4:40-8. [PMID: 22395480 DOI: 10.4161/isl.18659] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The Reg3 peptides INGAP-PP and human Reg3α/β (HIP) have been hypothesized to stimulate β-cell neogenesis in the pancreas. Administration of INGAP-PP has been shown to cause an increase in β-cell mass in multiple animal models, reverse streptozotocin (STZ) induced diabetes in mice and reduces HbA1c levels in type 2 diabetic humans. In this study, we have examined the ability of the INGAP-PP and HIP peptides to induce β-cell formation in vivo in normal mice through short-term administration of the peptides. We assessed the peptides ability to induce an increase in extra-islet insulin-positive cell clusters by looking at β-cell number by point counting morphometry on pancreata that had been randomized using the smooth fractionator principle in non-diabetic NMRI mice after short-term injections of the peptides (5 d). Five day continuous BrdU labeling was used to determine if the new β-cells were derived from replicating β-cells. Real time quantitative RT-PCR and immuno-histochemistry was used to analyze changes in pancreatic transcription factor expression. A 1.5- to 2-fold increase in the volume of small extra-islet insulin-positive clusters post 5 d treatment with INGAP-PP and HIP as compared with mice treated with a non-peptide control or scrambled peptide (p<0.05) (n = 7) was found. Five day continuous BrdU infusion during the 5 d period showed little or no incorporation in islets or small insulin clusters. Five days of treatment with INGAP-PP or HIP, showed a tendency toward increased levels of pancreatic progenitor markers such as Ngn3, Nkx6.1, Sox9 and Ins. These are the first studies to compare and indicate that the human Reg3 α/β (HIP) peptide has similar bioactivity in vivo as INGAP by causing formation of small β-cell clusters in extra-islet pancreatic tissue after only 5 d of treatment. Upregulation of pancreatic transcription factors may be part of the mechanism of action.
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Affiliation(s)
- Rahul Kapur
- Department of Beta Cell Regeneration; Hagedorn Research Institute; Gentofte, Denmark
| | | | | | - Sif Groth Rønn
- Department of Incretin Biology; Hagedorn Research Institute; Gentofte, Denmark
| | - Allan E Karlsen
- Department of Beta Cell Regeneration; Hagedorn Research Institute; Gentofte, Denmark
| | - R Scott Heller
- Department of Beta Cell Regeneration; Hagedorn Research Institute; Gentofte, Denmark
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30
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Abstract
We have studied whether functional TRPV1 channels exist in the INS-1E cells, a cell type used as a model for β-cells, and in primary β-cells from rat and human. The effects of the TRPV1 agonists capsaicin and AM404 on the intracellular free Ca (2+) concentration ([Ca (2+)]i) in the INS-1E cells were studied by fura-2 based microfluorometry. Capsaicin increased [Ca (2+)]i in a concentration-dependent manner, and the [Ca (2+)]i increase was dependent on extracellular Ca (2+). AM404 also increased [Ca (2+)]i in the INS-1E cells. Capsazepine, a specific antagonist of TRPV1, completely blocked the capsaicin- and AM404-induced [Ca (2+)]i increases. Capsaicin did not increase [Ca (2+)]i in the primary β-cells from rat and human. Whole cell patch clamp configuration was used to record currents across the plasma membrane in the INS-1E cells. Capsaicin elicited inward currents that were inhibited by capsazepine. Western blot analysis detected TRPV1 proteins in the INS-1E cells and the human islets. Immunohistochemistry was used to study the expression of TRPV1, but no TRPV1 protein immunoreactivity was detected in the human islet cells and the human insulinoma cells. We conclude that the INS-1E cells, but not the primary β-cells, express functional TRPV1 channels.
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Affiliation(s)
- Amanda Jabin Fågelskiöld
- Department of Clinical Science and Education; Södersjukhuset; Karolinska Institutet; Stockholm, Sweden
| | - Kristina Kannisto
- Department of Clinical Science and Education; Södersjukhuset; Karolinska Institutet; Stockholm, Sweden
| | - Anna Boström
- Department of Clinical Science and Education; Södersjukhuset; Karolinska Institutet; Stockholm, Sweden
| | - Banina Hadrovic
- Department of Clinical Science and Education; Södersjukhuset; Karolinska Institutet; Stockholm, Sweden
| | | | - Mohamed Eweida
- Department of Clinical Science and Education; Södersjukhuset; Karolinska Institutet; Stockholm, Sweden
| | - Kenneth Wester
- Department of Genetics and Pathology; the Rudbeck Laboratory; Uppsala University; Uppsala, Sweden
| | - Md Shahidul Islam
- Department of Clinical Science and Education; Södersjukhuset; Karolinska Institutet; Stockholm, Sweden; Internal Medicine; Uppsala University Hospital; Uppsala, Sweden
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31
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Akirav EM, Lebastchi J, Galvan EM, Henegariu O, Akirav M, Ablamunits V, Lizardi PM, Herold KC. Detection of β cell death in diabetes using differentially methylated circulating DNA. Proc Natl Acad Sci U S A 2011; 108:19018-23. [PMID: 22074781 PMCID: PMC3223447 DOI: 10.1073/pnas.1111008108] [Citation(s) in RCA: 165] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In diabetes mellitus, β cell destruction is largely silent and can be detected only after significant loss of insulin secretion capacity. We have developed a method for detecting β cell death in vivo by amplifying and measuring the proportion of insulin 1 DNA from β cells in the serum. By using primers that are specific for DNA methylation patterns in β cells, we have detected circulating copies of β cell-derived demethylated DNA in serum of mice by quantitative PCR. Accordingly, we have identified a relative increase of β cell-derived DNA after induction of diabetes with streptozotocin and during development of diabetes in nonobese diabetic mice. We have extended the use of this assay to measure β cell-derived insulin DNA in human tissues and serum. We found increased levels of demethylated insulin DNA in subjects with new-onset type 1 diabetes compared with age-matched control subjects. Our method provides a noninvasive approach for detecting β cell death in vivo that may be used to track the progression of diabetes and guide its treatment.
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Affiliation(s)
- Eitan M. Akirav
- Department of Immunobiology and Internal Medicine, Yale University School of Medicine, New Haven, CT 06511
| | - Jasmin Lebastchi
- Department of Immunobiology and Internal Medicine, Yale University School of Medicine, New Haven, CT 06511
| | - Eva M. Galvan
- Department of Immunobiology and Internal Medicine, Yale University School of Medicine, New Haven, CT 06511
| | - Octavian Henegariu
- Department of Immunobiology and Internal Medicine, Yale University School of Medicine, New Haven, CT 06511
| | - Michael Akirav
- Faculty of Life Sciences, Bar-Ilan University, Ramat Gan 52900, Israel; and
| | - Vitaly Ablamunits
- Department of Immunobiology and Internal Medicine, Yale University School of Medicine, New Haven, CT 06511
| | - Paul M. Lizardi
- Department of Pathology, Yale University School of Medicine, New Haven, CT 06511
| | - Kevan C. Herold
- Department of Immunobiology and Internal Medicine, Yale University School of Medicine, New Haven, CT 06511
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Ziegler P, Teller S, Ha NH, Giese B, Fraunholz M, Walther R. Phosphoproteomic identification of a PDX-1/14-3-3ε interaction in pancreatic beta cells. Horm Metab Res 2011; 43:165-70. [PMID: 21287435 DOI: 10.1055/s-0030-1270526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Glucose-dependent activation of the homeodomain transcription factor PDX-1 leads to its phosphorylation, to an increase in DNA binding capacity, and to NLS dependent translocation into the nucleus. To uncover unknown mediators of PDX-1 activation, PDX-1 interacting proteins were analysed by pull-down from (32)P-labelled, glucose-stimulated MIN6 cells. Recovered proteins were analysed by 2D gel electrophoresis and mass spectrometry. We identified 14-3-3ε as a novel PDX-1 binding protein and confirmed the interaction in vivo by Fluorescence Resonance Energy Transfer (FRET) analysis. We propose that 14-3-3ε interacts directly with PDX-1 to regulate its cellular distribution in pancreatic beta cells.
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Affiliation(s)
- P Ziegler
- Department of Medical Biochemistry and Molecular Biology, University of Greifswald, Greifswald, Germany
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33
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Ruiz de Azua I, Gautam D, Guettier JM, Wess J. Novel insights into the function of β-cell M3 muscarinic acetylcholine receptors: therapeutic implications. Trends Endocrinol Metab 2011; 22:74-80. [PMID: 21106385 PMCID: PMC3053051 DOI: 10.1016/j.tem.2010.10.004] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Revised: 10/20/2010] [Accepted: 10/20/2010] [Indexed: 12/25/2022]
Abstract
Impaired function of pancreatic β-cells is one of the hallmarks of type 2 diabetes. β-cell function is regulated by the activity of many hormones and neurotransmitters, which bind to specific cell surface receptors. The M(3) muscarinic acetylcholine receptor (M3R) belongs to the superfamily of G protein-coupled receptors and, following ligand dependent activation, selectively activates G proteins of the G(q/11) family. Recent studies with M3R mutant mice strongly suggest that β-cell M3Rs play a central role in promoting insulin release and maintaining correct glucose homeostasis. In this review, we highlight recent studies indicating that β-cell M3Rs and components of downstream signaling pathways might represent promising new targets for the treatment of type 2 diabetes.
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Affiliation(s)
- Inigo Ruiz de Azua
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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34
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Buchanan CM, Phillips ARJ, Cooper GJS. A novel two-chain IGF-II-derived peptide from purified β-cell granules. Growth Horm IGF Res 2010; 20:360-366. [PMID: 20656537 DOI: 10.1016/j.ghir.2010.06.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2010] [Revised: 05/19/2010] [Accepted: 06/28/2010] [Indexed: 10/19/2022]
Abstract
OBJECTIVE Insulin-like growth factor II (IGF-II) is a potent mitogen that regulates prenatal growth and development in both humans and rodents. Its role in post-natal life is less clear although immunohistochemical studies have observed IGF-II-like immunoreactivity (IGF-II-LI) associated with insulin-producing pancreatic β-cells. Here we isolated secretory granules from a β-cell line, βTC6-F7, and characterized the nature of the IGF-II-LI located therein. DESIGN Secretory granules were isolated from cultured mouse βTC6-F7 cells by ultracentrifugation. Granule protein content was separated by reversed-phase HPLC, and assayed for IGF-II (radioimmunoassay) prior to identification by gas-phase NH(2)-terminal sequencing and MALDI-TOF MS. Effects of glucose incorporation into muscle glycogen were determined by incubating with isolated rat soleus muscle strips. RESULTS βTC6-F7 cells contained 60 ± 8 pmol of IGF-II-LI per 10⁶ cells compared to 340 ± 44 pmol insulin-LI per 10⁶ cells. IGF-II immunoreactive fractions were found to contain an IGF-II-like molecule with a molecular mass of 6847.6 Da. The protein was found to be a two-chain insulin-like product of Igf2 that corresponds to mouse des(37-40)IGF-II, which we termed 'vesiculin'. This molecule was also detectable in βTC6-F7 cells by intact-cell mass spectrometry. Mouse vesiculin evoked concentration-dependent stimulation of muscle glycogen synthesis ex vivo with an EC(50) value of 131 nM ± 1.35. CONCLUSIONS Vesiculin, des(37-40)IGF-II, is a novel two-chain insulin-like hormone and the major "IGF-II-like" peptide found in purified mouse βTC6-F7 secretory granules. It stimulated ex vivo muscle glycogen synthesis with an efficacy greater than or equal to the intrinsic potency of IGF-II when compared to insulin derived from the same species.
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Affiliation(s)
- Christina M Buchanan
- Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, New Zealand.
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35
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Schubert S, Knoch KP, Ouwendijk J, Mohammed S, Bodrov Y, Jäger M, Altkrüger A, Wegbrod C, Adams ME, Kim Y, Froehner SC, Jensen ON, Kalaidzidis Y, Solimena M. β2-Syntrophin is a Cdk5 substrate that restrains the motility of insulin secretory granules. PLoS One 2010; 5:e12929. [PMID: 20886068 PMCID: PMC2944849 DOI: 10.1371/journal.pone.0012929] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2009] [Accepted: 08/23/2010] [Indexed: 11/18/2022] Open
Abstract
The molecular basis for the interaction of insulin granules with the cortical cytoskeleton of pancreatic β-cells remains unknown. We have proposed that binding of the granule protein ICA512 to the PDZ domain of β2-syntrophin anchors granules to actin filaments and that the phosphorylation/dephosphorylation of β2-syntrophin regulates this association. Here we tested this hypothesis by analyzing INS-1 cells expressing GFP-β2-syntrophin through the combined use of biochemical approaches, imaging studies by confocal and total internal reflection fluorescence microscopy as well as electron microscopy. Our results support the notion that β2-syntrophin restrains the mobility of cortical granules in insulinoma INS-1 cells, thereby reducing insulin secretion and increasing insulin stores in resting cells, while increasing insulin release upon stimulation. Using mass spectrometry, in vitro phosphorylation assays and β2-syntrophin phosphomutants we found that phosphorylation of β2-syntrophin on S75 near the PDZ domain decreases its binding to ICA512 and correlates with increased granule motility, while phosphorylation of S90 has opposite effects. We further show that Cdk5, which regulates insulin secretion, phosphorylates S75. These findings provide mechanistic insight into how stimulation displaces insulin granules from cortical actin, thus promoting their motility and exocytosis.
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Affiliation(s)
- Sandra Schubert
- Molecular Diabetology, Paul Langerhans Institute Dresden, Uniklinikum Carl Gustav Carus at Dresden University of Technology, Dresden, Germany
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Klaus-Peter Knoch
- Molecular Diabetology, Paul Langerhans Institute Dresden, Uniklinikum Carl Gustav Carus at Dresden University of Technology, Dresden, Germany
| | - Joke Ouwendijk
- Molecular Diabetology, Paul Langerhans Institute Dresden, Uniklinikum Carl Gustav Carus at Dresden University of Technology, Dresden, Germany
| | - Shabaz Mohammed
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Yury Bodrov
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Melanie Jäger
- Molecular Diabetology, Paul Langerhans Institute Dresden, Uniklinikum Carl Gustav Carus at Dresden University of Technology, Dresden, Germany
| | - Anke Altkrüger
- Molecular Diabetology, Paul Langerhans Institute Dresden, Uniklinikum Carl Gustav Carus at Dresden University of Technology, Dresden, Germany
| | - Carolin Wegbrod
- Molecular Diabetology, Paul Langerhans Institute Dresden, Uniklinikum Carl Gustav Carus at Dresden University of Technology, Dresden, Germany
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Marvin E. Adams
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington, United States of America
| | - Yong Kim
- Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York, New York, United States of America
| | - Stanley C. Froehner
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington, United States of America
| | - Ole N. Jensen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Yannis Kalaidzidis
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia
| | - Michele Solimena
- Molecular Diabetology, Paul Langerhans Institute Dresden, Uniklinikum Carl Gustav Carus at Dresden University of Technology, Dresden, Germany
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
- * E-mail:
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36
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Rauf F, Huang Y, Muhandiramlage TP, Aspinwall CA. Analysis of protein kinase A activity in insulin-secreting cells using a cell-penetrating protein substrate and capillary electrophoresis. Anal Bioanal Chem 2010; 397:3359-67. [PMID: 20458471 PMCID: PMC3064950 DOI: 10.1007/s00216-010-3776-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2010] [Revised: 04/19/2010] [Accepted: 04/22/2010] [Indexed: 10/19/2022]
Abstract
A cell-penetrating, fluorescent protein substrate was developed to monitor intracellular protein kinase A (PKA) activity in cells without the need for cellular transfection. The PKA substrate (PKAS) was prepared with a 6xhistidine purification tag, an enhanced green fluorescent protein (EGFP) reporter, an HIV-TAT protein transduction domain for cellular translocation and a pentaphosphorylation motif specific for PKA. PKAS was expressed in Escherichia coli and purified by metal affinity chromatography. Incubation of PKAS in the extracellular media facilitated translocation into the intracellular milieu in HeLa cells, betaTC-3 cells and pancreatic islets with minimal toxicity in a time and concentration dependent manner. Upon cellular loading, glucose-dependent phosphorylation of PKAS was observed in both betaTC-3 cells and pancreatic islets via capillary zone electrophoresis. In pancreatic islets, maximal PKAS phosphorylation (83 +/- 6%) was observed at 12 mM glucose, whereas maximal PKAS phosphorylation (86 +/- 4%) in betaTC-3 cells was observed at 3 mM glucose indicating a left-shifted glucose sensitivity. Increased PKAS phosphorylation was observed in the presence of PKA stimulators forskolin and 8-Br-cAMP (33% and 16%, respectively), with corresponding decreases in PKAS phosphorylation observed in the presence of PKA inhibitors staurosporine and H-89 (40% and 54%, respectively).
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Affiliation(s)
- Femina Rauf
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | - Yiding Huang
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | | | - Craig A. Aspinwall
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
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37
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González-Pertusa JA, Dubé J, Valle SR, Rosa TC, Takane KK, Mellado-Gil JM, Perdomo G, Vasavada RC, García-Ocaña A. Novel proapoptotic effect of hepatocyte growth factor: synergy with palmitate to cause pancreatic {beta}-cell apoptosis. Endocrinology 2010; 151:1487-98. [PMID: 20176723 PMCID: PMC2850223 DOI: 10.1210/en.2009-0975] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Increasing evidence suggests that elevation of plasma fatty acids that often accompanies insulin resistance contributes to beta-cell insufficiency in obesity-related type 2 diabetes. Circulating levels of hepatocyte growth factor (HGF) are increased in humans with metabolic syndrome and obesity. HGF is known to protect beta-cells against streptozotocin and during islet engraftment. However, whether HGF is a beta-cell prosurvival factor in situations of excessive lipid supply has not been deciphered. Mice overexpressing HGF in the beta-cell [rat insulin type II promoter (RIP)-HGF transgenic mice] fed with standard chow display improved glucose homeostasis and increased beta-cell mass and proliferation compared with normal littermates. However, after 15 wk of high-fat feeding, glucose homeostasis and beta-cell expansion and proliferation are indistinguishable between normal and transgenic mice. Interestingly, RIP-HGF transgenic mouse beta-cells and normal beta-cells treated with HGF display increased sensitivity to palmitate-mediated apoptosis in vitro. Palmitate completely eliminates Akt and Bad phosphorylation in RIP-HGF transgenic mouse islets. HGF-overexpressing islets also show significantly decreased AMP-activated protein kinase-alpha and acetyl-coenzyme A carboxylase phosphorylation, diminished fatty acid oxidation, increased serine palmitoyltransferase expression, and enhanced ceramide formation compared with normal islets. Importantly, human islets overexpressing HGF also display increased beta-cell apoptosis in the presence of palmitate. Treatment of both mouse and human islet cells with the de novo ceramide synthesis inhibitors myriocin and fumonisin B1 abrogates beta-cell apoptosis induced by HGF and palmitate. Collectively, these studies indicate that HGF can be detrimental for beta-cell survival in an environment with excessive fatty acid supply.
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Affiliation(s)
- José A González-Pertusa
- Division of Endocrinology, University of Pittsburgh, 200 Lothrop Street, BST-E1140, Pittsburgh, Pennsylvania 15261, USA
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38
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Hanley SC, Austin E, Assouline-Thomas B, Kapeluto J, Blaichman J, Moosavi M, Petropavlovskaia M, Rosenberg L. {beta}-Cell mass dynamics and islet cell plasticity in human type 2 diabetes. Endocrinology 2010; 151:1462-72. [PMID: 20176718 DOI: 10.1210/en.2009-1277] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Studies of long-standing type 2 diabetes (T2D) report a deficit in beta-cell mass due to increased apoptosis, whereas neogenesis and replication are unaffected. It is unclear whether these changes are a cause or a consequence of T2D. Moreover, whereas islet morphogenetic plasticity has been demonstrated in vitro, the in situ plasticity of islets, as well as the effect of T2D on endocrine differentiation, is unknown. We compared beta-cell volume, neogenesis, replication, and apoptosis in pancreata from lean and obese (body mass index > or = 27 kg/m(2)) diabetic (5 +/- 2 yr since diagnosis) and nondiabetic cadaveric donors. We also subjected isolated islets from diabetic (3 +/- 1 yr since diagnosis) and nondiabetic donors to an established in vitro model of islet plasticity. Differences in beta-cell volume between diabetic and nondiabetic donors were consistently less pronounced than those reported in long-standing T2D. A compensatory increase in beta-cell neogenesis appeared to mediate this effect. Studies of induced plasticity indicated that islets from diabetic donors were capable of epithelial dedifferentiation but did not demonstrate regenerative potential, as was seen in islets from nondiabetic donors. This deficiency was associated with the overexpression of Notch signaling molecules and a decreased neurogenin-3(+) cell frequency. One interpretation of these results would be that decreased beta-cell volume is a consequence, not a cause, of T2D, mediated by increased apoptosis and attenuated beta-cell (re)generation. However, other explanations are also possible. It remains to be seen whether the morphogenetic plasticity of human islets, deficient in vitro in islets from diabetic donors, is a component of normal beta-cell mass dynamics.
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Affiliation(s)
- Stephen C Hanley
- M.Eng., Montréal General Hospital C9-128, 1650 Cedar Avenue, Montréal, Québec, Canada H3G 1A4
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Huang H, Xie Q, Kang M, Zhang B, Zhang H, Chen J, Zhai C, Yang D, Jiang B, Wu Y. Labeling transplanted mice islet with polyvinylpyrrolidone coated superparamagnetic iron oxide nanoparticles for in vivo detection by magnetic resonance imaging. Nanotechnology 2009; 20:365101. [PMID: 19687538 DOI: 10.1088/0957-4484/20/36/365101] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Superparamagnetic iron oxide nanoparticles (SPIO) are emerging as a novel probe for noninvasive cell tracking with magnetic resonance imaging (MRI) and have potential wide usage in medical research. In this study, we have developed a method using high-temperature hydrolysis of chelate metal alkoxide complexes to synthesize polyvinylpyrrolidone coated iron oxide nanoparticles (PVP-SPIO), as a biocompatible magnetic agent that can efficiently label mice islet beta-cells. The size, crystal structure and magnetic properties of the as-synthesized nanoparticles have been characterized. The newly synthesized PVP-SPIO with high stability, crystallinity and saturation magnetization can be efficiently internalized into beta-cells, without affecting viability and function. The imaging of 100 PVP-SPIO-labeled mice islets in the syngeneic renal subcapsular model of transplantation under a clinical 3.0 T MR imager showed high spatial resolution in vivo. These results indicated the great potential application of the PVP-SPIO as an MRI contrast agent for monitoring transplanted islet grafts in the clinical management of diabetes in the near future.
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Affiliation(s)
- Hai Huang
- Department of Surgery, 2nd Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, PR China
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40
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Abstract
Recently, we have identified matrix pH as a key regulator of mitochondrial energy metabolism in the β-cell (Wiederkehr et al. EMBO J. (2009) 28(4):417-28). Under resting glucose conditions matrix pH in β-cell mitochondria is unusually low (pH 7.25). Following nutrient stimulation of rat islets matrix alkalinisation occurs raising matrix pH to 7.7 a value close to those determined in other cell types (pH 7.8-8.1). Alkalinisation follows a very similar time-course as net increases of the cytosolic ATP levels and is associated with a 2.5-fold elevation of the mitochondrial ATP synthesis rate. Suppression of this alkalinisation using nigericin almost completely abolishes mitochondrial ATP synthesis in a permeabilised cell system. Our working hypothesis is that low mitochondrial pH maintains the β-cell mitochondria in an inactive state, whereas nutrient stimulation favors alkalinisation and full activation of mitochondrial energy metabolism, resulting in mitochondrial signal generation and insulin granule exocytosis.
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Affiliation(s)
- Andreas Wiederkehr
- Department of Cell Physiology and Metabolism, University Medical Center, Geneva Switzerland.
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41
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Abstract
Previously, the insulin producing liver cell line HUH7-ins has been shown to synthesize, store and secrete insulin in response to glucose via secretory granules. The current study characterized the gene expression profile of HUH7-ins with the aim to identify changes possibly involved in the formation of granules. Additionally, experiments were conducted to determine the influence of chromogranin A (CgA) on secretory granule biogenesis (SGB) in HUH7-ins. Expression of 165 genes were significantly changed in HUH7-ins,though interestingly the majority of secretory granule associated genes, such as the chromogranins were unchanged. CgA was over-expressed in glucose unresponsive HUH7-ins cells to test whether CgA played a role in SGB and would restore the regulated secretory phenotype. Over-expression affected neither the storage nor regulated secretion of insulin. These data suggest that SGB may by regulated at a post-transcriptional level with no evidence to indicate that CgA regulates SGB in the cell line HUH7-ins.
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Affiliation(s)
- Mark A Lutherborrow
- Diabetes Transplant Unit, Prince of Wales Hospital, Sydney, New South Wales, Australia
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42
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Tews D, Lehr S, Hartwig S, Osmers A, Paslack W, Eckel J. Anti-apoptotic action of exendin-4 in INS-1 beta cells: comparative protein pattern analysis of isolated mitochondria. Horm Metab Res 2009; 41:294-301. [PMID: 19085810 DOI: 10.1055/s-0028-1105911] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Glucagon like peptide-1 (Glp-1) exhibits beneficial effects on beta cell mass by both enhancing proliferation and inhibiting apoptosis. The precise mechanism of the anti-apoptotic effect of Glp-1 and Glp-1 mimetics like exendin-4 has remained elusive. Here, we studied cytokine-induced apoptosis in the pancreatic beta cell line INS-1 and performed a comparative mitochondrial protein pattern analysis using two-dimensional difference gel electrophoresis (2D-DIGE). Cytokine incubation of INS-1 cells increased caspase-3 activity about 3-fold, which was reduced by 60% in the presence of exendin-4. Production of reactive oxygen species in response to cytokines was completely prevented after preincubation with exendin-4. Highly purified mitochondria were obtained and mitochondrial proteins were labeled with Cy-dyes and separated on overlapping zoom 2D gels spanning a pH-range of 4-9. Protein spots with significant changes after cytokine and exendin-4 treatment were identified by MALDI mass spectrometry. Comparing all treatment conditions, comparative mitochondrial proteome analysis allowed to identify 33 different proteins, which were significantly altered between comparison groups. Changes in protein patterns revealed involvement of cytokine-induced electron transport chain damage. Thus, cytochrome bc1 complex subunit I and ATP synthase subunit beta were downregulated by 30-40%. This was abrogated by the presence of exendin-4. In conclusion, this study provides further insights into the role of mitochondria in cytokine-induced apoptosis. We show here that exendin-4 significantly counter-regulates the reduced abundance of electron transport chain proteins, leading to a reduction of oxidative stress and most likely contributing to the anti-apoptotic action of this drug.
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Affiliation(s)
- D Tews
- Institute of Clinical Biochemistry and Pathobiochemistry, German Diabetes Center, Düsseldorf, Germany
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43
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Adisakwattana S, Moonsan P, Yibchok-Anun S. Insulin-releasing properties of a series of cinnamic acid derivatives in vitro and in vivo. J Agric Food Chem 2008; 56:7838-7844. [PMID: 18651742 DOI: 10.1021/jf801208t] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Cinnamic acid derivatives are naturally occurring substances found in fruits, vegetables, and flowers and are consumed as dietary phenolic compounds. In the present study, cinnamic acid and its derivatives were evaluated for insulin secreting activity in perfused rat pancreas and pancreatic beta-cells (INS-1) as well as an increase in [Ca(2+)]i in vitro. The presence of m-hydroxy or p-methoxy residues on cinnamic acid was a significantly important substituent as an effective insulin releasing agent. The introduction of p-hydroxy and m-methoxy-substituted groups in cinnamic acid structure (ferulic acid) displayed the most potent insulin secreting agent among those of cinnamic acid derivatives. In particular, the stimulatory insulin secreting activities of test compounds were associated with a rise of [Ca(2+)]i in INS-1. In perfused rat pancreas, m-hydroxycinnamic acid, p-methoxycinnamic acid, and ferulic acid (100 microM) significantly stimulated insulin secretion during 10 min of administration. The onset time of insulin secretion of those compounds was less than 1 min and reached its peak at 4 min that was about 2.8-, 3.3-, and 3.4-fold of the baseline level, respectively. Intravenous administration of p-methoxycinnamic acid and ferulic acid (5 mg/kg) significantly decreased plasma glucose and increased insulin concentration in normal rats and maintained its level for 15 min until the end of experiment. Meanwhile, m-hydroxycinnamic acid induced a significant lowering of plasma glucose after 6 min, but the effects were transient with plasma glucose concentration, rapidly returning to basal levels. Our findings suggested that p-methoxycinnamic acid and ferulic acid may be beneficial for the treatment of diabetes mellitus because they regulated blood glucose level by stimulating insulin secretion from pancreatic beta-cells.
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Affiliation(s)
- Sirichai Adisakwattana
- Department of Transfusion Medicine, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, Thailand.
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44
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Nordentoft I, Jeppesen PB, Hong J, Abudula R, Hermansen K. Increased insulin sensitivity and changes in the expression profile of key insulin regulatory genes and beta cell transcription factors in diabetic KKAy-mice after feeding with a soy bean protein rich diet high in isoflavone content. J Agric Food Chem 2008; 56:4377-4385. [PMID: 18522411 DOI: 10.1021/jf800504r] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
High content isoflavone soy protein (SBP) (Abalon) has been found in animal studies to possess beneficial effects on a number of the characteristic features of the insulin resistance syndrome. The aim of this study was to investigate whether SBP exerts beneficial effects on metabolism in the diabetic KKAy-mouse. Furthermore, we investigated the long-term in vivo effect of SBP on the expression profile in islets of key insulin regulatory genes. Twenty KKAy-mice, aged 5 weeks, were divided into 2 groups and treated for 9 weeks with either (A) standard chow diet (control) or (B) chow + 50% SBP. Twenty normal C57BL-mice fed with standard chow diet served as nondiabetic controls (C). Blood samples were collected and analyzed before and after intervention. Gene expression was determined in islets by quantitative real-time RT-PCR and Affymetrix microarray. It was demonstrated that long-term treatment with SBP improves glucose homeostasis, increases insulin sensitivity, and lowers plasma triglycerides in diabetic KKAy-mice. SBP reduces fasting plasma glucose, insulin, triglycerides, and total cholesterol. Furthermore, SBP markedly changes the gene expression profile of key insulin regulatory genes GLUT2, GLUT3, Ins1, Ins2, IGF1, Beta2/Neurod1, cholecystokinin, and LDLr, and proliferative genes in islets isolated from KKAy-mice. After 9 weeks of treatment with SBP, plasma glucose and insulin homeostasis was normalized compared to start levels. The results indicate that SBP improves glucose and insulin sensitivity and up-regulates the expression of key insulin regulatory genes.
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Affiliation(s)
- I Nordentoft
- Department of Endocrinology and Metabolism C, Aarhus Sygehus THG, Aarhus University Hospital, Tage-Hansens Gade 2, DK-8000 Aarhus C, Denmark.
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Wellershaus K, Degen J, Deuchars J, Theis M, Charollais A, Caille D, Gauthier B, Janssen-Bienhold U, Sonntag S, Herrera P, Meda P, Willecke K. A new conditional mouse mutant reveals specific expression and functions of connexin36 in neurons and pancreatic beta-cells. Exp Cell Res 2008; 314:997-1012. [PMID: 18258229 DOI: 10.1016/j.yexcr.2007.12.024] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2007] [Revised: 12/20/2007] [Accepted: 12/20/2007] [Indexed: 11/19/2022]
Abstract
Connexin36 (Cx36) is the main connexin isoform expressed in neurons of the central nervous system (CNS) and in pancreatic beta-cells, i.e. two types of excitable cells that share - in spite of their different origins - a number of common features. Previous studies on Cx36 deficient mice have documented that loss of Cx36 resulted in phenotypic abnormalities in both the CNS and the pancreas which, however, could not be attributed to specific cell types due to the general deletion nature of the animal model used. Attempts to address this limitation using cell type specific deletions generated by the Cre/loxP strategy have so far been complicated by the lack of Cx36 expression from the floxed allele. We have now generated a conditional Cx36 deficient mouse mutant in which the coding region of Cx36 is flanked by loxP sites, followed by a cyan fluorescent protein (CFP) reporter gene. Here we show that Cx36 was still expressed from the floxed allele in neurons and pancreatic beta-cells. In these cells, a 30-60% decrease of this protein, relative to the expression level of the wildtype allele, did not significantly perturb cell coupling. The deletion of Cx36 by ubiquitously and cell type specifically expressed Cre recombinases revealed that CFP functions as a reliable reporter for Cx36 expression in brain neurons and to some extent in retina neurons, but not in pancreas. Loss of Cx36 by Cre-mediated recombination was documented at transcript and protein levels. Cell type specific deletion of Cx36 in the endocrine pancreas revealed major alterations in the basal as well as the glucose-induced insulin secretion, hence specifically attributing to pancreatic Cx36 an important regulatory role in the control of beta-cell function. Cell type specific deletion of Cx36 in the CNS by suitable Cre recombinases should also help to elucidate the functional role of Cx36 in different neuronal subtypes.
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Affiliation(s)
- Kerstin Wellershaus
- Institute of Genetics, Division of Molecular Genetics, University of Bonn, Roemerstrasse 164, Bonn, Germany
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Mirhashemi F, Kluth O, Scherneck S, Vogel H, Kluge R, Schürmann A, Joost HG, Neschen S. High-fat, carbohydrate-free diet markedly aggravates obesity but prevents beta-cell loss and diabetes in the obese, diabetes-susceptible db/db strain. Obes Facts 2008; 1:292-7. [PMID: 20054191 PMCID: PMC6452171 DOI: 10.1159/000176064] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
OBJECTIVE We have previously reported that a high-fat, carbohydrate-free diet prevents diabetes and beta-cell destruction in the New Zealand Obese (NZO) mouse strain. Here we investigated the effect of diets with and without carbohydrates on obesity and development of beta-cell failure in a second mouse model of type 2 diabetes, the db/db mouse. RESULTS When kept on a carbohydrate-containing standard (SD; with (w/w) 5.1, 58.3, and 17.6% fat, carbohydrates and protein, respectively) or high-fat diet (HFD; 14.6, 46.7 and 17.1%), db/db mice developed severe diabetes (blood glucose >20 mmol/l, weight loss, polydipsia and polyurea) associated with a selective loss of pancreatic beta-cells, reduced GLUT2 expression in the remaining beta-cells, and reduced plasma insulin levels. In contrast, db/db mice kept on a high-fat, carbohydrate-free diet (CFD; with 30.2 and 26.4% (w/w) fat or protein) did not develop diabetes and exhibited near-normal, hyperplastic islets in spite of a morbid obesity (fat content >60%) associated with hyperinsulinaemia. CONCLUSION These data indicate that in genetically different mouse models of obesity-associated diabetes, obesity and dietary fat are not sufficient, and dietary carbohydrates are required, for beta-cell destruction.
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Affiliation(s)
| | | | | | | | | | | | - Hans-Georg Joost
- *Prof. Dr. Hans-Georg Joost, German Institute of Human Nutrition, Arthur-Scheunert-Allee 114–116, 14558, Nuthetal, Germany Tel. +49 33200 88-216, Fax -555,
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Aldibbiat A, Marriott CE, Scougall KT, Campbell SC, Huang GC, Macfarlane WM, Shaw JAM. Inability to process and store proinsulin in transdifferentiated pancreatic acinar cells lacking the regulated secretory pathway. J Endocrinol 2008; 196:33-43. [PMID: 18180315 DOI: 10.1677/joe-07-0397] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Generation of new beta-cells from the adult pancreas or the embryonic stem cells is being pursued by research groups worldwide. Success will be dependent on confirmation of true beta-cell phenotype evidenced by capacity to process and store proinsulin. The aim of these studies was to robustly determine endocrine characteristics of the AR42J rat pancreatic acinar cell line before and after in vitro transdifferentiation. beta-cell phenotypic marker expression was characterised by RT-PCR, immunostaining, western blotting, ELISA and in human preproinsulin transgene over-expression studies in wild-type AR42J cells and after culture on Matrigel basement membrane matrix with and without growth/differentiation factor supplementation. Pancreatic duodenal homeobox 1 (PDX1), forkhead box transcription factor a2 (Foxa2), glucokinase, pancreatic polypeptide and low-level insulin gene transcription in wild-type AR42J cells were confirmed by RT-PCR. Culture on Matrigel-coated plates and supplementation of medium with glucagon-like peptide 1 induced expression of the beta-cell Glut 2 with maintained expression of insulin and PDX1. Increased biosynthesis and secretion of proinsulin were confirmed by immunocytochemical staining and sensitive ELISA. Absence of the regulated secretory pathway was demonstrated by undetectable prohormone convertase expression. In addition, inability to process and store endogenous proinsulin or human proinsulin translated from a constitutively over-expressed preproinsulin transgene was confirmed. The importance of robust phenotypic characterisation at the protein level in attempted beta-cell transdifferentiation studies has been confirmed. Rodent and human sensitive/specific differential proinsulin/insulin ELISA in combination with human preproinsulin over-expression enables detailed elucidatation of core endocrine functions of proinsulin processing and storage in putative new beta-cells.
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Affiliation(s)
- A Aldibbiat
- Diabetes Research Group, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
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Abstract
OBJECTIVES Intranuclear rodlets (INRs) are rod-shaped intranuclear inclusions that we have described in neurons of the human brain. We recently identified these structures in pancreatic islet cells. The objectives of this study are to describe the light microscopic features and cellular pattern of distribution of INRs in human pancreatic islet cells. METHODS Double immunofluorescence staining was performed on 5 human pancreatic tissue samples for the detection of class III beta tubulin (C3T) to detect INRs and for promyelocytic leukemia (PML) protein to examine the relationship between PML and INRs. RESULTS Intranuclear rodlets were detected in 22.99% of pancreatic B cells compared with only 3.11%, 1.80%, and 1.60% of A, D, and PP cells, respectively. Twenty-four percent of C3T-immunoreactive INRs showed partial or complete immunoreactivity for PML. Promyelocytic leukemia staining within the nuclei of B cells was confined to INRs and was not present in the typical PML bodies present in other cell types. Spatially, PML and C3T staining of islet cell INRs appeared to be mutually exclusive within individual INRs. CONCLUSIONS Intranuclear rodlets are present within the nuclei of pancreatic islet cells, where they reside predominantly but not exclusively in B cells. Immunoreactivity of B-cell INRs for PML suggests that the functional significance of INRs may be related to that of PML and/or PML bodies. Conversely, the exclusive localization of PML staining to INRs in B cells indicates that PML's function in B cells is selectively associated with INRs. The mutually exclusive pattern of PML and C3T staining suggests dynamic interactions between these 2 proteins in B-cell INRs. In light of evidence for the involvement of INRs and of PML bodies in disease, it will be of interest to investigate these structures in animal models of diabetes and in human diabetes.
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Affiliation(s)
- Wendy Prichett
- Centre for Cancer Therapeutics, The Ottawa Health Research Institute, Ottawa, Ontario, Canada
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Blixt M, Niklasson B, Sandler S. Characterization of beta-cell function of pancreatic islets isolated from bank voles developing glucose intolerance/diabetes: an animal model showing features of both type 1 and type 2 diabetes mellitus, and a possible role of the Ljungan virus. Gen Comp Endocrinol 2007; 154:41-7. [PMID: 17686482 DOI: 10.1016/j.ygcen.2007.06.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2007] [Revised: 06/21/2007] [Accepted: 06/22/2007] [Indexed: 10/23/2022]
Abstract
Bank voles (Clethrionomys glareolus) kept in captivity develop diabetes mellitus to a significant extent. Also in wild bank voles, elevated blood glucose has been observed. A newly isolated picornavirus named Ljungan virus (LV) has been found in the pancreas of these bank voles. Moreover, LV infection in combination with environmental factors may cause glucose intolerance/diabetes (GINT/D) in normal mice. The aim of the present study was to investigate the functional characteristics of pancreatic islets, isolated from bank voles, bred in the laboratory but considered LV infected. About 20% of all males and females were classified as GINT/D following a glucose tolerance test. Of these animals the majority had become diabetic by 20 weeks of age, with a tendency towards an earlier onset in the males. GINT/D animals had increased serum insulin levels. Islets were tested on the day of isolation (day 0) and after 1 week of culture for their insulin content and their capacity to synthesize (pro)insulin, secrete insulin and metabolize glucose. Functional differences could be observed between normal and GINT/D animals as well as between genders. An elevated basal insulin secretion was observed on day 0 indicating beta-cell dysfunction among islets isolated from diabetic males. In vitro culture could reverse some functional changes. The increased serum insulin level and the increased basal islet insulin secretion may suggest that the animals had developed a type 2 diabetes-like condition. It is likely that the putative stress imposed in the laboratory, maybe in combination with LV infection, can lead to an increased functional demand on the beta-cells.
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Affiliation(s)
- Martin Blixt
- Department of Medical Cell Biology, Uppsala University, Uppsala Biomedical Centre, Box 571, Husargatan 3, SE-751 23 Uppsala, Sweden.
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Harris PE, Ferrara C, Barba P, Polito T, Freeby M, Maffei A. VMAT2 gene expression and function as it applies to imaging beta-cell mass. J Mol Med (Berl) 2007; 86:5-16. [PMID: 17665159 DOI: 10.1007/s00109-007-0242-x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2007] [Revised: 06/06/2007] [Accepted: 06/27/2007] [Indexed: 12/14/2022]
Abstract
Diabetes mellitus is a metabolic disorder characterized by hyperglycemia. The two main forms of the disease are distinguished by different pathogenesis, natural histories, and population distributions and indicated as either type 1 (T1DM) or type 2 diabetes mellitus (T2DM). It is well established that T1DM is an autoimmune disease whereby beta-cells of pancreatic islets are destroyed leading to loss of endogenous insulin production. Albeit less dramatic, beta-cell mass (BCM) also drops in T2DM. Therefore, it is realistic to expect that noninvasive measures of BCM might provide useful information in the diabetes-care field. Preclinical studies have demonstrated that BCM measurements by positron emission tomography scanning, using the vesicular monoamine transporter type 2 (VMAT2) as a tissue-specific surrogate marker of insulin production and [11C] Dihydrotetrabenazine (DTBZ) as the radioligand specific for this molecule, is feasible in animal models. Unfortunately, the mechanisms underlying beta-cell-specific expression of VMAT2 are still largely unexplored, and a much better understanding of the regulation of VMAT2 gene expression and of its function in beta-cells will be required before the full utility of this technique in the prediction and treatment of individuals with diabetes can be understood. In this review, we summarize much of what is understood about the regulation of VMAT2 and identify questions whose answers may help in understanding what measurements of VMAT2 density mean in the context of diabetes.
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Affiliation(s)
- Paul E Harris
- Institute of Genetics and Biophysics Adriano Buzzati-Traverso, CNR, Naples, Italy.
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