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Bramwell LR, Gould SJ, Davies M, McMullan C, Trusler EC, Harries LW. An Evaluation of the Replacement of Animal-derived Biomaterials in Human Primary Cell Culture. Altern Lab Anim 2024; 52:247-260. [PMID: 39121342 DOI: 10.1177/02611929241269004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/11/2024]
Abstract
The likelihood that potential new drugs will successfully navigate the current translational pipeline is poor, with fewer than 10% of drug candidates making this transition successfully, even after their entry into clinical trials. Prior to this stage, candidate drugs are typically evaluated by using models of increasing complexity, beginning with basic in vitro cell culture studies and progressing through to animal studies, where many of these candidates are lost due to lack of efficacy or toxicology concerns. There are many reasons for this poor translation, but interspecies differences in functional and physiological parameters undoubtedly contribute to the problem. Improving the human-relevance of early preclinical in vitro models may help translatability, especially when targeting more nuanced species-specific cell processes. The aim of the current study was to define a set of guidelines for the effective transition of human primary cells of multiple lineages to more physiologically relevant, translatable, animal-free in vitro culture conditions. Animal-derived biomaterials (ADBs) were systematically replaced with non-animal-derived alternatives in the in vitro cell culture systems, and the impact of the substitutions subsequently assessed by comparing the kinetics and phenotypes of the cultured cells. ADBs were successfully eliminated from primary human dermal fibroblast, uterine fibroblast, pulmonary fibroblast, retinal endothelial cell and peripheral blood mononuclear cell culture systems, and the individual requirements of each cell subtype were defined to ensure the successful transition toward growth under animal-free culture conditions. We demonstrate that it is possible to transition ('humanise') a diverse set of human primary cell types by following a set of simple overarching principles that inform the selection, and guide the evaluation of new, improved, human-relevant in vitro culture conditions.
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Affiliation(s)
- Laura R Bramwell
- RNA-Mediated Mechanisms of Disease Group, Department of Clinical and Biomedical Sciences, University of Exeter, Exeter, UK
| | - Samantha J Gould
- RNA-Mediated Mechanisms of Disease Group, Department of Clinical and Biomedical Sciences, University of Exeter, Exeter, UK
| | - Merlin Davies
- RNA-Mediated Mechanisms of Disease Group, Department of Clinical and Biomedical Sciences, University of Exeter, Exeter, UK
| | - Conor McMullan
- Islet Biology Group (IBEx), Department of Clinical and Biomedical Sciences, University of Exeter, Exeter, UK
| | - Emily C Trusler
- Technical Services, Department of Clinical and Biomedical Sciences, University of Exeter, Exeter, UK
| | - Lorna W Harries
- RNA-Mediated Mechanisms of Disease Group, Department of Clinical and Biomedical Sciences, University of Exeter, Exeter, UK
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2
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Grenko CM, Taylor HJ, Bonnycastle LL, Xue D, Lee BN, Weiss Z, Yan T, Swift AJ, Mansell EC, Lee A, Robertson CC, Narisu N, Erdos MR, Chen S, Collins FS, Taylor DL. Single-cell transcriptomic profiling of human pancreatic islets reveals genes responsive to glucose exposure over 24 h. Diabetologia 2024:10.1007/s00125-024-06214-4. [PMID: 38967666 DOI: 10.1007/s00125-024-06214-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Accepted: 05/08/2024] [Indexed: 07/06/2024]
Abstract
AIMS/HYPOTHESIS Disruption of pancreatic islet function and glucose homeostasis can lead to the development of sustained hyperglycaemia, beta cell glucotoxicity and subsequently type 2 diabetes. In this study, we explored the effects of in vitro hyperglycaemic conditions on human pancreatic islet gene expression across 24 h in six pancreatic cell types: alpha; beta; gamma; delta; ductal; and acinar. We hypothesised that genes associated with hyperglycaemic conditions may be relevant to the onset and progression of diabetes. METHODS We exposed human pancreatic islets from two donors to low (2.8 mmol/l) and high (15.0 mmol/l) glucose concentrations over 24 h in vitro. To assess the transcriptome, we performed single-cell RNA-seq (scRNA-seq) at seven time points. We modelled time as both a discrete and continuous variable to determine momentary and longitudinal changes in transcription associated with islet time in culture or glucose exposure. Additionally, we integrated genomic features and genetic summary statistics to nominate candidate effector genes. For three of these genes, we functionally characterised the effect on insulin production and secretion using CRISPR interference to knock down gene expression in EndoC-βH1 cells, followed by a glucose-stimulated insulin secretion assay. RESULTS In the discrete time models, we identified 1344 genes associated with time and 668 genes associated with glucose exposure across all cell types and time points. In the continuous time models, we identified 1311 genes associated with time, 345 genes associated with glucose exposure and 418 genes associated with interaction effects between time and glucose across all cell types. By integrating these expression profiles with summary statistics from genetic association studies, we identified 2449 candidate effector genes for type 2 diabetes, HbA1c, random blood glucose and fasting blood glucose. Of these candidate effector genes, we showed that three (ERO1B, HNRNPA2B1 and RHOBTB3) exhibited an effect on glucose-stimulated insulin production and secretion in EndoC-βH1 cells. CONCLUSIONS/INTERPRETATION The findings of our study provide an in-depth characterisation of the 24 h transcriptomic response of human pancreatic islets to glucose exposure at a single-cell resolution. By integrating differentially expressed genes with genetic signals for type 2 diabetes and glucose-related traits, we provide insights into the molecular mechanisms underlying glucose homeostasis. Finally, we provide functional evidence to support the role of three candidate effector genes in insulin secretion and production. DATA AVAILABILITY The scRNA-seq data from the 24 h glucose exposure experiment performed in this study are available in the database of Genotypes and Phenotypes (dbGap; https://www.ncbi.nlm.nih.gov/gap/ ) with accession no. phs001188.v3.p1. Study metadata and summary statistics for the differential expression, gene set enrichment and candidate effector gene prediction analyses are available in the Zenodo data repository ( https://zenodo.org/ ) under accession number 11123248. The code used in this study is publicly available at https://github.com/CollinsLabBioComp/publication-islet_glucose_timecourse .
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Affiliation(s)
- Caleb M Grenko
- Center for Precision Health Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
- Graduate School of Biomedical Sciences, Mayo Clinic, Rochester, MN, USA
| | - Henry J Taylor
- Center for Precision Health Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA.
- British Heart Foundation Cardiovascular Epidemiology Unit, Department of Public Health and Primary Care, University of Cambridge, Cambridge, UK.
- Heart and Lung Research Institute, University of Cambridge, Cambridge, UK.
| | - Lori L Bonnycastle
- Center for Precision Health Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Dongxiang Xue
- Department of Surgery, Weill Cornell Medicine, New York, NY, USA
- Center for Genomic Health, Weill Cornell Medicine, New York, NY, USA
| | - Brian N Lee
- Center for Precision Health Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Zoe Weiss
- Center for Precision Health Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Tingfen Yan
- Center for Precision Health Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Amy J Swift
- Center for Precision Health Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Erin C Mansell
- Center for Precision Health Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Angela Lee
- Center for Precision Health Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Catherine C Robertson
- Center for Precision Health Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, USA
| | - Narisu Narisu
- Center for Precision Health Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Michael R Erdos
- Center for Precision Health Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Shuibing Chen
- Department of Surgery, Weill Cornell Medicine, New York, NY, USA
- Center for Genomic Health, Weill Cornell Medicine, New York, NY, USA
| | - Francis S Collins
- Center for Precision Health Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA.
| | - D Leland Taylor
- Center for Precision Health Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
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3
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Leenders F, de Koning EJP, Carlotti F. Pancreatic β-Cell Identity Change through the Lens of Single-Cell Omics Research. Int J Mol Sci 2024; 25:4720. [PMID: 38731945 PMCID: PMC11083883 DOI: 10.3390/ijms25094720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Revised: 04/12/2024] [Accepted: 04/17/2024] [Indexed: 05/13/2024] Open
Abstract
The main hallmark in the development of both type 1 and type 2 diabetes is a decline in functional β-cell mass. This decline is predominantly attributed to β-cell death, although recent findings suggest that the loss of β-cell identity may also contribute to β-cell dysfunction. This phenomenon is characterized by a reduced expression of key markers associated with β-cell identity. This review delves into the insights gained from single-cell omics research specifically focused on β-cell identity. It highlights how single-cell omics based studies have uncovered an unexpected level of heterogeneity among β-cells and have facilitated the identification of distinct β-cell subpopulations through the discovery of cell surface markers, transcriptional regulators, the upregulation of stress-related genes, and alterations in chromatin activity. Furthermore, specific subsets of β-cells have been identified in diabetes, such as displaying an immature, dedifferentiated gene signature, expressing significantly lower insulin mRNA levels, and expressing increased β-cell precursor markers. Additionally, single-cell omics has increased insight into the detrimental effects of diabetes-associated conditions, including endoplasmic reticulum stress, oxidative stress, and inflammation, on β-cell identity. Lastly, this review outlines the factors that may influence the identification of β-cell subpopulations when designing and performing a single-cell omics experiment.
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Affiliation(s)
| | | | - Françoise Carlotti
- Department of Internal Medicine, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands; (F.L.); (E.J.P.d.K.)
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Puri S, Maachi H, Nair G, Russ HA, Chen R, Pulimeno P, Cutts Z, Ntranos V, Hebrok M. Sox9 regulates alternative splicing and pancreatic beta cell function. Nat Commun 2024; 15:588. [PMID: 38238288 PMCID: PMC10796970 DOI: 10.1038/s41467-023-44384-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 12/12/2023] [Indexed: 01/22/2024] Open
Abstract
Despite significant research, mechanisms underlying the failure of islet beta cells that result in type 2 diabetes (T2D) are still under investigation. Here, we report that Sox9, a transcriptional regulator of pancreas development, also functions in mature beta cells. Our results show that Sox9-depleted rodent beta cells have defective insulin secretion, and aging animals develop glucose intolerance, mimicking the progressive degeneration observed in T2D. Using genome editing in human stem cells, we show that beta cells lacking SOX9 have stunted first-phase insulin secretion. In human and rodent cells, loss of Sox9 disrupts alternative splicing and triggers accumulation of non-functional isoforms of genes with key roles in beta cell function. Sox9 depletion reduces expression of protein-coding splice variants of the serine-rich splicing factor arginine SRSF5, a major splicing enhancer that regulates alternative splicing. Our data highlight the role of SOX9 as a regulator of alternative splicing in mature beta cell function.
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Affiliation(s)
- Sapna Puri
- Diabetes Center, Department of Medicine, University of California, San Francisco, CA, USA
- Minutia Inc., Oakland, CA, USA
| | - Hasna Maachi
- Diabetes Center, Department of Medicine, University of California, San Francisco, CA, USA
- Center for Organoid Systems, Klinikum Rechts der Isar (MRI) and Technical University Munich, 85748, Garching, Germany
- Institute for Diabetes Organoid Technology, Helmholtz Munich, Helmholtz Diabetes Center, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany
- Munich Institute of Biomedical Engineering (MIBE), Technical University Munich, Munich, Germany
- German Center for Diabetes Research (DZD), Ingolstaedter Landstrasse 1, 85764, Neuherberg, Germany
| | - Gopika Nair
- Diabetes Center, Department of Medicine, University of California, San Francisco, CA, USA
- Eli Lilly, Indianapolis, IN, USA
| | - Holger A Russ
- Diabetes Center, Department of Medicine, University of California, San Francisco, CA, USA
- Diabetes Institute, University of Florida, Gainesville, FL, USA
- Department of Pharmacology and Therapeutics, University of Florida, Gainesville, FL, USA
| | - Richard Chen
- Diabetes Center, Department of Medicine, University of California, San Francisco, CA, USA
| | - Pamela Pulimeno
- Diabetes Center, Department of Medicine, University of California, San Francisco, CA, USA
| | - Zachary Cutts
- Graduate Program in Bioinformatics, University of California, San Francisco, CA, USA
| | - Vasilis Ntranos
- Diabetes Center, Department of Medicine, University of California, San Francisco, CA, USA
| | - Matthias Hebrok
- Diabetes Center, Department of Medicine, University of California, San Francisco, CA, USA.
- Center for Organoid Systems, Klinikum Rechts der Isar (MRI) and Technical University Munich, 85748, Garching, Germany.
- Institute for Diabetes Organoid Technology, Helmholtz Munich, Helmholtz Diabetes Center, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany.
- Munich Institute of Biomedical Engineering (MIBE), Technical University Munich, Munich, Germany.
- German Center for Diabetes Research (DZD), Ingolstaedter Landstrasse 1, 85764, Neuherberg, Germany.
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Cota P, Caliskan ÖS, Bastidas-Ponce A, Jing C, Jaki J, Saber L, Czarnecki O, Taskin D, Blöchinger AK, Kurth T, Sterr M, Burtscher I, Krahmer N, Lickert H, Bakhti M. Insulin regulates human pancreatic endocrine cell differentiation in vitro. Mol Metab 2024; 79:101853. [PMID: 38103636 PMCID: PMC10765254 DOI: 10.1016/j.molmet.2023.101853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 11/21/2023] [Accepted: 12/11/2023] [Indexed: 12/19/2023] Open
Abstract
OBJECTIVE The consequences of mutations in genes associated with monogenic forms of diabetes on human pancreas development cannot be studied in a time-resolved fashion in vivo. More specifically, if recessive mutations in the insulin gene influence human pancreatic endocrine lineage formation is still an unresolved question. METHODS To model the extremely reduced insulin levels in patients with recessive insulin gene mutations, we generated a novel knock-in H2B-Cherry reporter human induced pluripotent stem cell (iPSC) line expressing no insulin upon differentiation to stem cell-derived (SC-) β cells in vitro. Differentiation of iPSCs into the pancreatic and endocrine lineage, combined with immunostaining, Western blotting and proteomics analysis phenotypically characterized the insulin gene deficiency in SC-islets. Furthermore, we leveraged FACS analysis and confocal microscopy to explore the impact of insulin shortage on human endocrine cell induction, composition, differentiation and proliferation. RESULTS Interestingly, insulin-deficient SC-islets exhibited low insulin receptor (IR) signaling when stimulated with glucose but displayed increased IR sensitivity upon treatment with exogenous insulin. Furthermore, insulin shortage did not alter neurogenin-3 (NGN3)-mediated endocrine lineage induction. Nevertheless, lack of insulin skewed the SC-islet cell composition with an increased number in SC-β cell formation at the expense of SC-α cells. Finally, insulin deficiency reduced the rate of SC-β cell proliferation but had no impact on the expansion of SC-α cells. CONCLUSIONS Using iPSC disease modelling, we provide first evidence of insulin function in human pancreatic endocrine lineage formation. These findings help to better understand the phenotypic impact of recessive insulin gene mutations during pancreas development and shed light on insulin gene function beside its physiological role in blood glucose regulation.
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Affiliation(s)
- Perla Cota
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany; School of Medicine, Technical University of Munich (TUM), Munich, Germany
| | - Özüm Sehnaz Caliskan
- German Center for Diabetes Research (DZD), Neuherberg, Germany; Institute of Diabetes and Obesity, Helmholtz Munich, Neuherberg, Germany
| | - Aimée Bastidas-Ponce
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Changying Jing
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany; Munich medical research school (MMRS), Ludwig Maximilian University (LMU), Munich, Germany
| | - Jessica Jaki
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Lama Saber
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany; School of Medicine, Technical University of Munich (TUM), Munich, Germany
| | - Oliver Czarnecki
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany; School of Medicine, Technical University of Munich (TUM), Munich, Germany
| | - Damla Taskin
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany
| | - Anna Karolina Blöchinger
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Thomas Kurth
- Center for Molecular and Cellular Bioengineering (CMCB), Technology Platform Core Facility Electron Microscopy and Histology, Technische Universität Dresden, Dresden, Germany
| | - Michael Sterr
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Ingo Burtscher
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany
| | - Natalie Krahmer
- German Center for Diabetes Research (DZD), Neuherberg, Germany; Institute of Diabetes and Obesity, Helmholtz Munich, Neuherberg, Germany
| | - Heiko Lickert
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany; School of Medicine, Technical University of Munich (TUM), Munich, Germany.
| | - Mostafa Bakhti
- Institute of Diabetes and Regeneration Research, Helmholtz Munich, Neuherberg, Germany; German Center for Diabetes Research (DZD), Neuherberg, Germany.
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6
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Thomas P, Gallagher MT, Da Silva Xavier G. Beta cell lipotoxicity in the development of type 2 diabetes: the need for species-specific understanding. Front Endocrinol (Lausanne) 2023; 14:1275835. [PMID: 38144558 PMCID: PMC10739424 DOI: 10.3389/fendo.2023.1275835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 11/13/2023] [Indexed: 12/26/2023] Open
Abstract
The propensity to develop type 2 diabetes (T2D) is known to have both environmental and hereditary components. In those with a genetic predisposition to T2D, it is widely believed that elevated concentrations of circulatory long-chain fatty acids (LC-FFA) significantly contribute towards the demise of insulin-producing pancreatic β-cells - the fundamental feature of the development of T2D. Over 25 years of research support that LC-FFA are deleterious to β-cells, through a process termed lipotoxicity. However, the work underpinning the theory of β-cell lipotoxicity is mostly based on rodent studies. Doubts have been raised as to whether lipotoxicity also occurs in humans. In this review, we examine the evidence, both in vivo and in vitro, for the pathogenic effects of LC-FFA on β-cell viability and function in humans, highlighting key species differences. In this way, we aim to uncover the role of lipotoxicity in the human pathogenesis of T2D and motivate the need for species-specific understanding.
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Affiliation(s)
- Patricia Thomas
- Centre for Systems Modelling and Quantitative Biomedicine, University of Birmingham, Birmingham, United Kingdom
- Institute for Metabolism and Systems Research, Birmingham Medical School, University of Birmingham, Birmingham, United Kingdom
| | - Meurig T. Gallagher
- Centre for Systems Modelling and Quantitative Biomedicine, University of Birmingham, Birmingham, United Kingdom
- Institute for Metabolism and Systems Research, Birmingham Medical School, University of Birmingham, Birmingham, United Kingdom
| | - Gabriela Da Silva Xavier
- Institute for Metabolism and Systems Research, Birmingham Medical School, University of Birmingham, Birmingham, United Kingdom
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7
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Moss ND, Wells KL, Theis A, Kim YK, Spigelman AF, Liu X, MacDonald PE, Sussel L. Modulation of insulin secretion by RBFOX2-mediated alternative splicing. Nat Commun 2023; 14:7732. [PMID: 38007492 PMCID: PMC10676425 DOI: 10.1038/s41467-023-43605-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 11/15/2023] [Indexed: 11/27/2023] Open
Abstract
Insulin secretion is a tightly regulated process that is vital for maintaining blood glucose homeostasis. Although the molecular components of insulin granule trafficking and secretion are well established, how they are regulated to rapidly fine-tune secretion in response to changing environmental conditions is not well characterized. Recent studies have determined that dysregulation of RNA-binding proteins (RBPs) and aberrant mRNA splicing occurs at the onset of diabetes. We demonstrate that the RBP, RBFOX2, is a critical regulator of insulin secretion through the alternative splicing of genes required for insulin granule docking and exocytosis. Conditional mutation of Rbfox2 in the mouse pancreas results in decreased insulin secretion and impaired blood glucose homeostasis. Consistent with defects in secretion, we observe reduced insulin granule docking and corresponding splicing defects in the SNARE complex components. These findings identify an additional mechanism for modulating insulin secretion in both healthy and dysfunctional pancreatic β cells.
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Affiliation(s)
- Nicole D Moss
- Barbara Davis Center for Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Kristen L Wells
- Barbara Davis Center for Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Alexandra Theis
- Barbara Davis Center for Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Yong-Kyung Kim
- Barbara Davis Center for Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Aliya F Spigelman
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
| | - Xiong Liu
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
| | - Patrick E MacDonald
- Department of Pharmacology and Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
| | - Lori Sussel
- Barbara Davis Center for Diabetes, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
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Chen X, Xie X, Li J, Sun L, Lv Z, Yao X, Li L, Jin H, Cui S, Liu J. BCAS2 Participates in Insulin Synthesis and Secretion via mRNA Alternative Splicing in Mice. Endocrinology 2023; 165:bqad152. [PMID: 37820033 DOI: 10.1210/endocr/bqad152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2023] [Revised: 09/22/2023] [Accepted: 10/09/2023] [Indexed: 10/13/2023]
Abstract
Insulin secreted by pancreatic β cells is essential for maintaining blood glucose levels. Diabetes is caused primarily by a loss of β cells or impairment of β-cell function. A previous whole-transcriptome analysis of islets from a type 2 diabetes group and a control group showed that a splicing disorder occurred in approximately 25% of splicing events. Breast carcinoma amplified sequence 2 (BCAS2) is a spliceosome component whose function in islet β cells is unclear. Here, we report that knockdown of Bcas2 decreased glucose- and KCl-stimulated insulin secretion in the NIT-1 cell line. Pancreas weight, glucose tolerance, and insulin sensitivity were measured in normal chow-fed Bcas2 f/f-βKO mice, and β-cell mass and islet size were analyzed by immunohistochemistry. Glucose intolerance developed in Bcas2 f/f-βKO mice, but there were no significant differences in pancreas weight, insulin sensitivity, β-cell mass, or islet size. Furthermore, observation of glucose-stimulated insulin secretion and insulin secretion granules in normal chow-fed mice revealed that the insulin level in serum and the number of insulin secretion granules were decreased in Bcas2 f/f-βKO mice. These differences were related to abnormal splicing of Syt7 and Tcf7l2 pre-mRNA. Taken together, these results demonstrate that BCAS2 is involved in alternative splicing during insulin synthesis and secretion.
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Affiliation(s)
- Xuexue Chen
- State Key Laboratory of Animal Biotech Breeding, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Xiaomei Xie
- State Key Laboratory of Animal Biotech Breeding, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Jianhua Li
- Reproductive Medical Center, Department of Obstetrics and Gynecology, the Seventh Medical Center of PLA General Hospital, Beijing 100007, China
| | - Longjie Sun
- State Key Laboratory of Animal Biotech Breeding, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Zheng Lv
- State Key Laboratory of Animal Biotech Breeding, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Xiaohong Yao
- State Key Laboratory of Animal Biotech Breeding, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Lei Li
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Hua Jin
- Department of Pathology, the Seventh Medical Center of PLA General Hospital, Beijing 100007, China
| | - Sheng Cui
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu 225009, China
| | - Jiali Liu
- State Key Laboratory of Animal Biotech Breeding, College of Biological Sciences, China Agricultural University, Beijing 100193, China
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9
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Atkinson MA, Mirmira RG. The pathogenic "symphony" in type 1 diabetes: A disorder of the immune system, β cells, and exocrine pancreas. Cell Metab 2023; 35:1500-1518. [PMID: 37478842 PMCID: PMC10529265 DOI: 10.1016/j.cmet.2023.06.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 06/22/2023] [Accepted: 06/28/2023] [Indexed: 07/23/2023]
Abstract
Type 1 diabetes (T1D) is widely considered to result from the autoimmune destruction of insulin-producing β cells. This concept has been a central tenet for decades of attempts seeking to decipher the disorder's pathogenesis and prevent/reverse the disease. Recently, this and many other disease-related notions have come under increasing question, particularly given knowledge gained from analyses of human T1D pancreas. Perhaps most crucial are findings suggesting that a collective of cellular constituents-immune, endocrine, and exocrine in origin-mechanistically coalesce to facilitate T1D. This review considers these emerging concepts, from basic science to clinical research, and identifies several key remaining knowledge voids.
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Affiliation(s)
- Mark A Atkinson
- Department of Pathology, Immunology, and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, FL 32610, USA.
| | - Raghavendra G Mirmira
- Departments of Medicine and Pediatrics, The University of Chicago, Chicago, IL 60637, USA
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10
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Wu W, Syed F, Simpson E, Lee CC, Liu J, Chang G, Dong C, Seitz C, Eizirik DL, Mirmira RG, Liu Y, Evans-Molina C. The Impact of Pro-Inflammatory Cytokines on Alternative Splicing Patterns in Human Islets. Diabetes 2021; 71:db200847. [PMID: 34697029 PMCID: PMC8763875 DOI: 10.2337/db20-0847] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Accepted: 10/18/2021] [Indexed: 01/05/2023]
Abstract
Alternative splicing (AS) within the β cell has been proposed as one potential pathway that may exacerbate autoimmunity and unveil novel immunogenic epitopes in type 1 diabetes (T1D). We employed a computational strategy to prioritize pathogenic splicing events in human islets treated with IL-1β + IFN-γ as an ex vivo model of T1D and coupled this analysis with a k-mer based approach to predict RNA binding proteins involved in AS. In total, 969 AS events were identified in cytokine-treated islets, with the majority (44.8%) involving a skipped exon. ExonImpact identified 129 events predicted to impact protein structure. AS occurred with high frequency in MHC Class II-related mRNAs, and targeted qPCR validated reduced inclusion of Exon5 in the MHC Class II gene HLA-DMB. Single molecule RNA FISH confirmed increased HLA-DMB splicing in pancreatic sections from human donors with established T1D and autoantibody positivity. Serine and Arginine Rich Splicing Factor 2 was implicated in 37.2% of potentially pathogenic events, including Exon5 exclusion in HLA-DMB. Together, these data suggest that dynamic control of AS plays a role in the β cell response to inflammatory signals during T1D evolution.
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Affiliation(s)
- Wenting Wu
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA
- Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, Indiana
| | - Farooq Syed
- Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, Indiana
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN, USA
- Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Edward Simpson
- Department of BioHealth Informatics, Indiana University School of Informatics and Computing, Indianapolis, IN, USA
| | - Chih-Chun Lee
- Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, Indiana
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN, USA
- Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Jing Liu
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, IN, USA
| | - Garrick Chang
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, IN, USA
| | - Chuanpeng Dong
- Department of BioHealth Informatics, Indiana University School of Informatics and Computing, Indianapolis, IN, USA
| | - Clayton Seitz
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, IN, USA
| | - Decio L Eizirik
- ULB Center for Diabetes Research, Medical Faculty, Universitê Libre de Bruxelles (ULB), Brussels, Belgium
- Indiana Biosciences Research Institute (IBRI), Indianapolis, Indiana, USA
| | - Raghavendra G Mirmira
- Kovler Diabetes Center and Department of Medicine, The University of Chicago, Chicago, IL, USA
| | - Yunlong Liu
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Carmella Evans-Molina
- Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, Indiana
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN, USA
- Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
- Richard L. Roudebush VA Medical Center, Indiana University School of Informatics and Computing, Indianapolis, IN, USA
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11
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Dudek KD, Osipovich AB, Cartailler JP, Gu G, Magnuson MA. Insm1, Neurod1, and Pax6 promote murine pancreatic endocrine cell development through overlapping yet distinct RNA transcription and splicing programs. G3-GENES GENOMES GENETICS 2021; 11:6358139. [PMID: 34534285 PMCID: PMC8527475 DOI: 10.1093/g3journal/jkab303] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 08/19/2021] [Indexed: 11/13/2022]
Abstract
Insm1, Neurod1, and Pax6 are essential for the formation and function of pancreatic endocrine cells. Here, we report comparative immunohistochemical, transcriptomic, functional enrichment, and RNA splicing analyses of these genes using gene knock-out mice. Quantitative immunohistochemical analysis confirmed that elimination of each of these three factors variably impairs the proliferation, survival, and differentiation of endocrine cells. Transcriptomic analysis revealed that each factor contributes uniquely to the transcriptome although their effects were overlapping. Functional enrichment analysis revealed that genes downregulated by the elimination of Insm1, Neurod1, and Pax6 are commonly involved in mRNA metabolism, chromatin organization, secretion, and cell cycle regulation, and upregulated genes are associated with protein degradation, autophagy, and apoptotic process. Elimination of Insm1, Neurod1, and Pax6 impaired expression of many RNA-binding proteins thereby altering RNA splicing events, including for Syt14 and Snap25, two genes required for insulin secretion. All three factors are necessary for normal splicing of Syt14, and both Insm1 and Pax6 are necessary for the processing of Snap25. Collectively, these data provide new insights into how Insm1, Neurod1, and Pax6 contribute to the formation of functional pancreatic endocrine cells.
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Affiliation(s)
- Karrie D Dudek
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37232, USA.,Center for Stem Cell Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Anna B Osipovich
- Center for Stem Cell Biology, Vanderbilt University, Nashville, TN 37232, USA.,Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
| | | | - Guoquing Gu
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37232, USA.,Center for Stem Cell Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Mark A Magnuson
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37232, USA.,Center for Stem Cell Biology, Vanderbilt University, Nashville, TN 37232, USA.,Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232, USA
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12
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Jeffery N, Chambers D, Invergo BM, Ames RM, Harries LW. Changes to the identity of EndoC-βH1 beta cells may be mediated by stress-induced depletion of HNRNPD. Cell Biosci 2021; 11:144. [PMID: 34301309 PMCID: PMC8305497 DOI: 10.1186/s13578-021-00658-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 07/14/2021] [Indexed: 12/02/2022] Open
Abstract
Background Beta cell identity changes occur in the islets of donors with diabetes, but the molecular basis of this remains unclear. Protecting residual functional beta cells from cell identity changes may be beneficial for patients with diabetes. Results A somatostatin-positive cell population was induced in stressed clonal human EndoC-βH1 beta cells and was isolated using FACS. A transcriptomic characterisation of somatostatin-positive cells was then carried out. Gain of somatostatin-positivity was associated with marked dysregulation of the non-coding genome. Very few coding genes were differentially expressed. Potential candidate effector genes were assessed by targeted gene knockdown. Targeted knockdown of the HNRNPD gene induced the emergence of a somatostatin-positive cell population in clonal EndoC-βH1 beta cells comparable with that we have previously reported in stressed cells. Conclusions We report here a role for the HNRNPD gene in determination of beta cell identity in response to cellular stress. These findings widen our understanding of the role of RNA binding proteins and RNA biology in determining cell identity and may be important for protecting remaining beta cell reserve in diabetes. Supplementary Information The online version contains supplementary material available at 10.1186/s13578-021-00658-6.
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Affiliation(s)
- Nicola Jeffery
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Barrack Road, Exeter, EX2 5DW, UK
| | | | | | - Ryan M Ames
- University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
| | - Lorna W Harries
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Barrack Road, Exeter, EX2 5DW, UK.
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13
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Rehman SU, Schallschmidt T, Rasche A, Knebel B, Stermann T, Altenhofen D, Herwig R, Schürmann A, Chadt A, Al-Hasani H. Alternative exon splicing and differential expression in pancreatic islets reveals candidate genes and pathways implicated in early diabetes development. Mamm Genome 2021; 32:153-172. [PMID: 33880624 PMCID: PMC8128753 DOI: 10.1007/s00335-021-09869-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 04/03/2021] [Indexed: 12/29/2022]
Abstract
Type 2 diabetes (T2D) has a strong genetic component. Most of the gene variants driving the pathogenesis of T2D seem to target pancreatic β-cell function. To identify novel gene variants acting at early stage of the disease, we analyzed whole transcriptome data to identify differential expression (DE) and alternative exon splicing (AS) transcripts in pancreatic islets collected from two metabolically diverse mouse strains at 6 weeks of age after three weeks of high-fat-diet intervention. Our analysis revealed 1218 DE and 436 AS genes in islets from NZO/Hl vs C3HeB/FeJ. Whereas some of the revealed genes present well-established markers for β-cell failure, such as Cd36 or Aldh1a3, we identified numerous DE/AS genes that have not been described in context with β-cell function before. The gene Lgals2, previously associated with human T2D development, was DE as well as AS and localizes in a quantitative trait locus (QTL) for blood glucose on Chr.15 that we reported recently in our N2(NZOxC3H) population. In addition, pathway enrichment analysis of DE and AS genes showed an overlap of only half of the revealed pathways, indicating that DE and AS in large parts influence different pathways in T2D development. PPARG and adipogenesis pathways, two well-established metabolic pathways, were overrepresented for both DE and AS genes, probably as an adaptive mechanism to cope for increased cellular stress. Our results provide guidance for the identification of novel T2D candidate genes and demonstrate the presence of numerous AS transcripts possibly involved in islet function and maintenance of glucose homeostasis.
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Affiliation(s)
- Sayeed Ur Rehman
- Institute for Clinical Biochemistry and Pathobiochemistry, German Diabetes Center (DDZ), Leibniz Center for Diabetes Research at Heinrich Heine University, Medical Faculty, Duesseldorf, Germany.,German Center for Diabetes Research (DZD), München-Neuherberg, Germany.,Department of Biochemistry, School of Chemical and Life Sciences, Jamia Hamdard, New Delhi, 110062, India
| | - Tanja Schallschmidt
- Institute for Clinical Biochemistry and Pathobiochemistry, German Diabetes Center (DDZ), Leibniz Center for Diabetes Research at Heinrich Heine University, Medical Faculty, Duesseldorf, Germany.,German Center for Diabetes Research (DZD), München-Neuherberg, Germany
| | - Axel Rasche
- Department of Computational Molecular Biology, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Birgit Knebel
- Institute for Clinical Biochemistry and Pathobiochemistry, German Diabetes Center (DDZ), Leibniz Center for Diabetes Research at Heinrich Heine University, Medical Faculty, Duesseldorf, Germany.,German Center for Diabetes Research (DZD), München-Neuherberg, Germany
| | - Torben Stermann
- Institute for Clinical Biochemistry and Pathobiochemistry, German Diabetes Center (DDZ), Leibniz Center for Diabetes Research at Heinrich Heine University, Medical Faculty, Duesseldorf, Germany.,German Center for Diabetes Research (DZD), München-Neuherberg, Germany
| | - Delsi Altenhofen
- Institute for Clinical Biochemistry and Pathobiochemistry, German Diabetes Center (DDZ), Leibniz Center for Diabetes Research at Heinrich Heine University, Medical Faculty, Duesseldorf, Germany.,German Center for Diabetes Research (DZD), München-Neuherberg, Germany
| | - Ralf Herwig
- Department of Computational Molecular Biology, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Annette Schürmann
- German Center for Diabetes Research (DZD), München-Neuherberg, Germany.,German Institute of Human Nutrition, Potsdam, Germany
| | - Alexandra Chadt
- Institute for Clinical Biochemistry and Pathobiochemistry, German Diabetes Center (DDZ), Leibniz Center for Diabetes Research at Heinrich Heine University, Medical Faculty, Duesseldorf, Germany.,German Center for Diabetes Research (DZD), München-Neuherberg, Germany
| | - Hadi Al-Hasani
- Institute for Clinical Biochemistry and Pathobiochemistry, German Diabetes Center (DDZ), Leibniz Center for Diabetes Research at Heinrich Heine University, Medical Faculty, Duesseldorf, Germany. .,German Center for Diabetes Research (DZD), München-Neuherberg, Germany.
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14
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Vanderkruk B, Hoffman BG. Metabolism as a central regulator of β-cell chromatin state. FEBS J 2020; 288:3683-3693. [PMID: 32926557 DOI: 10.1111/febs.15562] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 08/06/2020] [Accepted: 09/07/2020] [Indexed: 02/06/2023]
Abstract
Pancreatic β-cells are critical mediators of glucose homeostasis in the body, and proper cellular nutrient metabolism is critical to β-cell function. Several interacting signaling networks that uniquely control β-cell metabolism produce essential substrates and co-factors for catalytic reactions, including reactions that modify chromatin. Chromatin modifications, in turn, regulate gene expression. The reactions that modify chromatin are therefore well-positioned to adjust gene expression programs according to nutrient availability. It follows that dysregulation of nutrient metabolism in β-cells may impact chromatin state and gene expression through altering the availability of these substrates and co-factors. Metabolic disorders such as type 2 diabetes (T2D) can significantly alter metabolite levels in cells. This suggests that a driver of β-cell dysfunction during T2D may be the altered availability of substrates or co-factors necessary to maintain β-cell chromatin state. Induced changes in the β-cell chromatin modifications may then lead to dysregulation of gene expression, in turn contributing to the downward cascade of events that leads to the loss of functional β-cell mass, and loss of glucose homeostasis, that occurs in T2D.
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Affiliation(s)
- Ben Vanderkruk
- Diabetes Research Group, British Columbia Children's Hospital Research Institute, Vancouver, BC, Canada.,Department of Surgery, University of British Columbia, Vancouver, BC, Canada.,Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Brad G Hoffman
- Diabetes Research Group, British Columbia Children's Hospital Research Institute, Vancouver, BC, Canada.,Department of Surgery, University of British Columbia, Vancouver, BC, Canada.,Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada
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15
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Moss ND, Sussel L. mRNA Processing: An Emerging Frontier in the Regulation of Pancreatic β Cell Function. Front Genet 2020; 11:983. [PMID: 33088281 PMCID: PMC7490333 DOI: 10.3389/fgene.2020.00983] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 08/03/2020] [Indexed: 01/04/2023] Open
Abstract
Robust endocrine cell function, particularly β cell function, is required to maintain blood glucose homeostasis. Diabetes can result from the loss or dysfunction of β cells. Despite decades of clinical and basic research, the precise regulation of β cell function and pathogenesis in diabetes remains incompletely understood. In this review, we highlight RNA processing of mRNAs as a rapidly emerging mechanism regulating β cell function and survival. RNA-binding proteins (RBPs) and RNA modifications are primed to be the next frontier to explain many of the poorly understood molecular processes that regulate β cell formation and function, and provide an exciting potential for the development of novel therapeutics. Here we outline the current understanding of β cell specific functions of several characterized RBPs, alternative splicing events, and transcriptome wide changes in RNA methylation. We also highlight several RBPs that are dysregulated in both Type 1 and Type 2 diabetes, and discuss remaining knowledge gaps in the field.
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Affiliation(s)
- Nicole D Moss
- Cell, Stem Cells, and Development Graduate Program, Department of Pediatrics, Barbara Davis Center, University of Colorado Denver Anschutz Medical Campus, Aurora, CO, United States
| | - Lori Sussel
- Cell, Stem Cells, and Development Graduate Program, Department of Pediatrics, Barbara Davis Center, University of Colorado Denver Anschutz Medical Campus, Aurora, CO, United States
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16
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Haque S, Ames RM, Moore K, Lee BP, Jeffery N, Harries LW. Islet-expressed circular RNAs are associated with type 2 diabetes status in human primary islets and in peripheral blood. BMC Med Genomics 2020; 13:64. [PMID: 32312268 PMCID: PMC7171860 DOI: 10.1186/s12920-020-0713-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Accepted: 04/14/2020] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Circular RNAs are non-coding RNA molecules with gene regulatory potential that have been associated with several human diseases. They are stable and present in the circulation, making them excellent candidates for biomarkers of disease. Despite their promise as biomarkers or future therapeutic targets, information on their expression and functionality in human pancreatic islets is a relatively unexplored subject. METHODS Here we aimed to produce an enriched circRNAome profile for human pancreatic islets by CircleSeq, and to explore the relationship between circRNA expression, diabetes status, genotype at T2D risk loci and measures of glycaemia (insulin secretory index; SI and HbA1c) in human islet preparations from healthy control donors and donors with type 2 diabetes using ANOVA or linear regression as appropriate. We also assessed the effect of elevated glucose, cytokine and lipid and hypoxia on circRNA expression in the human beta cell line EndoC-βH1. RESULTS We identified over 2600 circRNAs present in human islets. Of the five most abundant circRNAs in human islets, four (circCIRBP, circZKSCAN, circRPH3AL and circCAMSAP1) demonstrated marked associations with diabetes status. CircCIRBP demonstrated an association with insulin secretory index in isolated human islets and circCIRBP and circRPH3AL displayed altered expression with elevated fatty acid in treated EndoC-βH1 cells. CircCAMSAP1 was also noted to be associated with T2D status in human peripheral blood. No associations between circRNA expression and genotype at T2D risk loci were identified in our samples. CONCLUSIONS Our data suggest that circRNAs are abundantly expressed in human islets, and that some are differentially regulated in the islets of donors with type 2 diabetes. Some islet circRNAs are also expressed in peripheral blood and the expression of one, circCAMSAP1, correlates with diabetes status. These findings highlight the potential of circRNAs as biomarkers for T2D.
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Affiliation(s)
- Shahnaz Haque
- RNA-Mediated Mechanisms of Disease Group, Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, University of Exeter, RILD South, Barrack Road, Exeter, EX2 5DW, UK
| | - Ryan M Ames
- Biosciences, University of Exeter, Exeter, UK
| | - Karen Moore
- College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Benjamin P Lee
- RNA-Mediated Mechanisms of Disease Group, Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, University of Exeter, RILD South, Barrack Road, Exeter, EX2 5DW, UK
| | - Nicola Jeffery
- RNA-Mediated Mechanisms of Disease Group, Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, University of Exeter, RILD South, Barrack Road, Exeter, EX2 5DW, UK
| | - Lorna W Harries
- RNA-Mediated Mechanisms of Disease Group, Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, University of Exeter, RILD South, Barrack Road, Exeter, EX2 5DW, UK.
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17
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Lee BP, Smith M, Buffenstein R, Harries LW. Negligible senescence in naked mole rats may be a consequence of well-maintained splicing regulation. GeroScience 2020; 42:633-651. [PMID: 31927681 PMCID: PMC7205774 DOI: 10.1007/s11357-019-00150-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 12/27/2019] [Indexed: 02/07/2023] Open
Abstract
Naked mole-rats (NMRs) have amongst the longest lifespans relative to body size of any known, non-volant mammalian species. They also display an enhanced stress resistance phenotype, negligible senescence and very rarely are they burdened with chronic age-related diseases. Alternative splicing (AS) dysregulation is emerging as a potential driver of senescence and ageing. We hypothesised that the expression of splicing factors, important regulators of patterns of AS, may differ in NMRs when compared to other species with relatively shorter lifespans. We designed assays specific to NMR splicing regulatory factors and also to a panel of pre-selected brain-expressed genes known to demonstrate senescence-related alterations in AS in other species, and measured age-related changes in the transcript expression levels of these using embryonic and neonatal developmental stages through to extreme old age in NMR brain samples. We also compared splicing factor expression in both young mouse and NMR spleen and brain samples. Both NMR tissues showed approximately double the expression levels observed in tissues from similarly sized mice. Furthermore, contrary to observations in other species, following a brief period of labile expression in early life stages, adult NMR splicing factors and patterns of AS for functionally relevant brain genes remained remarkably stable for at least two decades. These findings are consistent with a model whereby the conservation of splicing regulation and stable patterns of AS may contribute to better molecular stress responses and the avoidance of senescence in NMRs, contributing to their exceptional lifespan and prolonged healthspan.
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Affiliation(s)
- B P Lee
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Barrack Road, Exeter, EX2 5DW, UK
| | - M Smith
- Calico Life Sciences LLC, 1170 Veterans Blvd., South San Francisco, CA, 94080, USA
| | - R Buffenstein
- Calico Life Sciences LLC, 1170 Veterans Blvd., South San Francisco, CA, 94080, USA.
| | - L W Harries
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Barrack Road, Exeter, EX2 5DW, UK.
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