51
|
Lehtonen J, Schäffer L, Rasch MG, Hecksher-Sørensen J, Ahnfelt-Rønne J. Beta cell specific probing with fluorescent exendin-4 is progressively reduced in type 2 diabetic mouse models. Islets 2015; 7:e1137415. [PMID: 26963143 PMCID: PMC4878261 DOI: 10.1080/19382014.2015.1137415] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Probes based on GLP-1R agonist exendin-4 have shown promise as in vivo β cell tracers. However, questions remain regarding the β cell specificity of exendin-4 probes, and it is unclear if the expression levels of the GLP-1R are affected in a type 2 diabetic state. Using in vivo probing followed by ex vivo imaging we found fluorescent exendin-4 probes to distinctly label the pancreatic islets in mice in a Glp-1r dependent manner. Furthermore, a co-localization study revealed a near 100 percent β cell specificity with less than one percent probing in other analyzed cell types. We then tested if probing was affected in models of type 2 diabetes using the Lepr(db/db) (db/db) and the Diet-Induced Obese (DIO) mouse. Although nearly all β cells continued to be probed, we observed a progressive decline in probing intensity in both models with the most dramatic reduction seen in db/db mice. This was paralleled by a progressive decrease in Glp-1r protein expression levels. These data confirm β cell specificity for exendin-4 based probes in mice. Furthermore, they also suggest that GLP-1R targeting probes may provide a tool to monitor β cell function rather than mass in type 2 diabetic mouse models.
Collapse
Affiliation(s)
- Janne Lehtonen
- Department of Histology & Imaging, Novo Nordisk A/S, Måløv, Denmark
| | - Lauge Schäffer
- Department of Protein & Peptide Chemistry, Novo Nordisk A/S, Måløv, Denmark
| | | | - Jacob Hecksher-Sørensen
- Department of Histology & Imaging, Novo Nordisk A/S, Måløv, Denmark
- Correspondence to: Jacob Hecksher-Sørensen;
| | | |
Collapse
|
52
|
Abstract
SLC30A8 encodes the secretory granule-resident and largely endocrine pancreas-restricted zinc transporter ZnT8. Interest in this gene product was sparked amongst diabetologists in 2007 when the first genome-wide association study for type 2 diabetes identified polymorphisms in SLC30A8 as affecting disease risk. Thus, the common polymorphism rs13266634 was associated with lowered beta cell function and a 14% increase in diabetes abundance per risk (C) allele. This non-synonymous variant encodes a tryptophan-to-arginine switch at position 325 in the protein's intracellular carboxy-terminal domain, resulting in reduced zinc transport activity and, consequently, decreased intragranular zinc levels. Whereas insulin secretion from isolated islets is most often increased in mice inactivated for Slc30a8, null animals usually show impaired glucose tolerance and lowered circulating insulin. Since Slc30a8 null animals display little, if any, zinc secretion from islets, the lower plasma insulin levels could be explained by increased hepatic clearance as a result of lowered local zinc levels, or less efficient insulin action on target tissues. Despite the emerging consensus on the role of ZnT8 in glucose homeostasis, a recent genetic study in humans has unexpectedly identified loss-of-function SLC30A8 mutants that are associated with protection from diabetes. Here, we attempt to reconcile these apparently contradictory findings, implicating (1) differing degrees of inhibition of ZnT8 activity in carriers of common variants vs rare loss-of-function forms, (2) effects dependent on age or hypoxic beta cell stress. We propose that these variables conspire to affect both the size and the direction of the effect of SLC30A8 risk alleles in man.
Collapse
Affiliation(s)
- Guy A Rutter
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial Centre for Translational and Experimental Medicine, Hammersmith Hospital, Imperial College London, Du Cane Road, London, W12 ONN, UK,
| | | |
Collapse
|
53
|
Rulifson IC, Majeti JZ, Xiong Y, Hamburger A, Lee KJ, Miao L, Lu M, Gardner J, Gong Y, Wu H, Case R, Yeh WC, Richards WG, Baribault H, Li Y. Inhibition of secreted frizzled-related protein 5 improves glucose metabolism. Am J Physiol Endocrinol Metab 2014; 307:E1144-52. [PMID: 25370851 DOI: 10.1152/ajpendo.00283.2014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Elucidating the role of secreted frizzled-related protein 5 (SFRP5) in metabolism and obesity has been complicated by contradictory findings when knockout mice were used to determine metabolic phenotypes. By overexpressing SFRP5 in obese, prediabetic mice we consistently observed elevated hyperglycemia and glucose intolerance, supporting SFRP5 as a negative regulator of glucose metabolism. Accordingly, Sfrp5 mRNA expression analysis of both epididymal and subcutaneous adipose depots of mice indicated a correlation with obesity. Thus, we generated a monoclonal antibody (mAb) against SFRP5 to ascertain the effect of SFRP5 inhibition in vivo. Congruent with SFRP5 overexpression worsening blood glucose levels and glucose intolerance, anti-SFRP5 mAb therapy improved these phenotypes in vivo. The results from both the overexpression and mAb inhibition studies suggest a role for SFRP5 in glucose metabolism and pancreatic β-cell function and thus establish the use of an anti-SFRP5 mAb as a potential approach to treat type 2 diabetes.
Collapse
Affiliation(s)
| | | | - Yumei Xiong
- Amgen Incorporated, South San Francisco, California; and
| | | | | | - Li Miao
- Amgen Incorporated, South San Francisco, California; and
| | - Mei Lu
- Amgen Incorporated, South San Francisco, California; and
| | | | - Yan Gong
- Amgen Incorporated, South San Francisco, California; and
| | - Hai Wu
- Amgen Incorporated, South San Francisco, California; and
| | - Ryan Case
- Amgen Incorporated, South San Francisco, California; and
| | - Wen-Chen Yeh
- Amgen Incorporated, South San Francisco, California; and
| | | | | | - Yang Li
- Amgen Incorporated, South San Francisco, California; and
| |
Collapse
|
54
|
Rutter GA. Dorothy Hodgkin Lecture 2014. Understanding genes identified by genome-wide association studies for type 2 diabetes. Diabet Med 2014; 31:1480-7. [PMID: 25186316 DOI: 10.1111/dme.12579] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Accepted: 08/22/2014] [Indexed: 01/09/2023]
Abstract
Whilst the heritable nature of Type 2 diabetes has been recognized for many years, only in the past two decades have linkage analyses in families and genome-wide association studies in large populations begun to reveal the genetic landscape of the disease in detail. Whilst the former have provided a powerful means of identifying the genes responsible for monogenic forms of the disease, the latter highlight relatively large genomic regions. These often harbour multiple genes, whose relative contribution to exaggerated disease risk is uncertain. In the present study, the approaches that have been used to dissect the role of just a few (TCF7L2, SLC30A8, ADCY5, MTNR1B and CDKAL1) of the ~ 500 genes identified at dozens of implicated loci are described. These are usually selected based on the strength of their effect on disease risk, and predictions as to their likely biological role. Direct determination of the effects of identified polymorphisms on gene expression in disease-relevant tissues, notably the pancreatic islet, are then performed to identify genes whose expression is affected by a particular polymorphism. Subsequent functional analyses then involve perturbing gene expression in vitro in β-cell lines or isolated islets and in vivo in animal models. Although the majority of polymorphisms affect insulin production rather than action, and mainly affect the β cell, effects via other tissues may also contribute, requiring careful consideration in the design and interpretation of experiments in model systems. These considerations illustrate the scale of the task needed to exploit genome-wide association study data for the development of new therapeutic strategies.
Collapse
Affiliation(s)
- G A Rutter
- Department of Medicine, Section of Cell Biology, Imperial College London, London, UK
| |
Collapse
|
55
|
Bailey KA, Savic D, Zielinski M, Park SY, Wang LJ, Witkowski P, Brady M, Hara M, Bell GI, Nobrega MA. Evidence of non-pancreatic beta cell-dependent roles of Tcf7l2 in the regulation of glucose metabolism in mice. Hum Mol Genet 2014; 24:1646-54. [PMID: 25398947 PMCID: PMC4381752 DOI: 10.1093/hmg/ddu577] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Non-coding variation within TCF7L2 remains the strongest genetic determinant of type 2 diabetes risk in humans. A considerable effort has been placed in understanding the functional roles of TCF7L2 in pancreatic beta cells, despite evidence of TCF7L2 expression in various peripheral tissues important in glucose homeostasis. Here, we use a humanized mouse model overexpressing Tcf7l2, resulting in glucose intolerance, to infer the contribution of Tcf7l2 overexpression in beta cells and in other tissues to the metabolic phenotypes displayed by these mice. Restoring Tcf7l2 expression specifically in beta cells to endogenous levels, in face of its overexpression elsewhere, results in impaired insulin secretion, reduced beta cell number and islet area, corroborating data obtained in humans showing similar phenotypes as a result of manipulations leading to Tcf7l2 loss of function. Interestingly, the persistent overexpression of Tcf7l2 in non-pancreatic tissues results in a significant worsening in glucose tolerance in vivo, indicating that Tcf7l2 overexpression in beta cells does not account for the glucose intolerance in the Tcf7l2 overexpression mouse model. Collectively, these data posit that Tcf7l2 plays key roles in glucose metabolism through actions beyond pancreatic beta cells, and further points to functionally opposing cell-type specific effects for Tcf7l2 on the maintenance of balanced glucose metabolism, thereby urging a careful examination of its role in non-pancreatic tissues as well as its composite metabolic effects across distinct tissues. Uncovering these roles may lead to new therapeutic targets for type 2 diabetes.
Collapse
Affiliation(s)
| | | | | | | | | | | | - Matthew Brady
- Department of Medicine, Section of Endocrinology, Diabetes, and Metabolism, University of Chicago, Chicago, IL 60637, USA
| | | | - Graeme I Bell
- Department of Human Genetics, Department of Medicine
| | | |
Collapse
|
56
|
Mitchell RK, Mondragon A, Chen L, Mcginty JA, French PM, Ferrer J, Thorens B, Hodson DJ, Rutter GA, Da Silva Xavier G. Selective disruption of Tcf7l2 in the pancreatic β cell impairs secretory function and lowers β cell mass. Hum Mol Genet 2014; 24:1390-9. [PMID: 25355422 PMCID: PMC4321446 DOI: 10.1093/hmg/ddu553] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Type 2 diabetes (T2D) is characterized by β cell dysfunction and loss. Single nucleotide polymorphisms in the T-cell factor 7-like 2 (TCF7L2) gene, associated with T2D by genome-wide association studies, lead to impaired β cell function. While deletion of the homologous murine Tcf7l2 gene throughout the developing pancreas leads to impaired glucose tolerance, deletion in the β cell in adult mice reportedly has more modest effects. To inactivate Tcf7l2 highly selectively in β cells from the earliest expression of the Ins1 gene (∼E11.5) we have therefore used a Cre recombinase introduced at the Ins1 locus. Tcfl2fl/fl::Ins1Cre mice display impaired oral and intraperitoneal glucose tolerance by 8 and 16 weeks, respectively, and defective responses to the GLP-1 analogue liraglutide at 8 weeks. Tcfl2fl/fl::Ins1Cre islets displayed defective glucose- and GLP-1-stimulated insulin secretion and the expression of both the Ins2 (∼20%) and Glp1r (∼40%) genes were significantly reduced. Glucose- and GLP-1-induced intracellular free Ca2+ increases, and connectivity between individual β cells, were both lowered by Tcf7l2 deletion in islets from mice maintained on a high (60%) fat diet. Finally, analysis by optical projection tomography revealed ∼30% decrease in β cell mass in pancreata from Tcfl2fl/fl::Ins1Cre mice. These data demonstrate that Tcf7l2 plays a cell autonomous role in the control of β cell function and mass, serving as an important regulator of gene expression and islet cell coordination. The possible relevance of these findings for the action of TCF7L2 polymorphisms associated with Type 2 diabetes in man is discussed.
Collapse
Affiliation(s)
- Ryan K Mitchell
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine
| | - Angeles Mondragon
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine
| | | | | | | | - Jorge Ferrer
- Section of Genetics and Medicine, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, London, UK
| | - Bernard Thorens
- Center for Integrative Genomics, Physiology Department, University of Lausanne, Genopode Building, CH-1015 Lausanne, Switzerland
| | - David J Hodson
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine
| | - Guy A Rutter
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine,
| | - Gabriela Da Silva Xavier
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine,
| |
Collapse
|
57
|
Chen L, Kumar S, Kelly D, Andrews N, Dallman MJ, French PMW, McGinty J. Remote focal scanning optical projection tomography with an electrically tunable lens. BIOMEDICAL OPTICS EXPRESS 2014; 5:3367-75. [PMID: 25360356 PMCID: PMC4206308 DOI: 10.1364/boe.5.003367] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Revised: 07/08/2014] [Accepted: 07/23/2014] [Indexed: 05/04/2023]
Abstract
We describe a remote focal scanning technique for optical projection tomography (OPT) implemented with an electrically tunable lens (ETL) that removes the need to scan the specimen or objective lens. Using a 4× objective lens the average spatial resolution is improved by ∼46% and the light collection efficiency by a factor of ∼6.76, thereby enabling increased acquisition speed and reduced light dose. This convenient implementation is particularly appropriate for lower magnifications and larger sample diameters where axial objective scanning would encounter problems with speed and stability.
Collapse
Affiliation(s)
- Lingling Chen
- Photonics Group, Department of Physics, Imperial College London, SW7 2AZ,
UK
| | - Sunil Kumar
- Photonics Group, Department of Physics, Imperial College London, SW7 2AZ,
UK
| | - Douglas Kelly
- Institute for Chemical Biology, Department of Chemistry, Imperial College London, SW7 2AZ,
UK
| | - Natalie Andrews
- Institute for Chemical Biology, Department of Chemistry, Imperial College London, SW7 2AZ,
UK
| | - Margaret J. Dallman
- Division of Cell and Molecular Biology, Department of Life Sciences, Imperial College London, SW7 2AZ,
UK
- Centre for Integrative Systems Biology, Department of Life Sciences, Imperial College London, SW7 2AZ,
UK
| | - Paul M. W. French
- Photonics Group, Department of Physics, Imperial College London, SW7 2AZ,
UK
| | - James McGinty
- Photonics Group, Department of Physics, Imperial College London, SW7 2AZ,
UK
| |
Collapse
|
58
|
Zatyka M, Da Silva Xavier G, Bellomo EA, Leadbeater W, Astuti D, Smith J, Michelangeli F, Rutter GA, Barrett TG. Sarco(endo)plasmic reticulum ATPase is a molecular partner of Wolfram syndrome 1 protein, which negatively regulates its expression. Hum Mol Genet 2014; 24:814-27. [PMID: 25274773 DOI: 10.1093/hmg/ddu499] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Wolfram syndrome is an autosomal recessive disorder characterized by neurodegeneration and diabetes mellitus. The gene responsible for the syndrome (WFS1) encodes an endoplasmic reticulum (ER)-resident transmembrane protein that is involved in the regulation of the unfolded protein response (UPR), intracellular ion homeostasis, cyclic adenosine monophosphate production and regulation of insulin biosynthesis and secretion. In this study, single cell Ca(2+) imaging with fura-2 and direct measurements of free cytosolic ATP concentration ([ATP]CYT) with adenovirally expressed luciferase confirmed a reduced and delayed rise in cytosolic free Ca(2+) concentration ([Ca(2+)]CYT), and additionally, diminished [ATP]CYT rises in response to elevated glucose concentrations in WFS1-depleted MIN6 cells. We also observed that sarco(endo)plasmic reticulum ATPase (SERCA) expression was elevated in several WFS1-depleted cell models and primary islets. We demonstrated a novel interaction between WFS1 and SERCA by co-immunoprecipitation in Cos7 cells and with endogenous proteins in human neuroblastoma cells. This interaction was reduced when cells were treated with the ER stress inducer dithiothreitol. Treatment of WFS1-depleted neuroblastoma cells with the proteasome inhibitor MG132 resulted in reduced accumulation of SERCA levels compared with wild-type cells. Together these results reveal a role for WFS1 in the negative regulation of SERCA and provide further insights into the function of WFS1 in calcium homeostasis.
Collapse
Affiliation(s)
| | - Gabriela Da Silva Xavier
- Department of Cell Biology, Division of Medicine, Faculty of Medicine, Imperial Centre for Translation and Experimental Medicine, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
| | - Elisa A Bellomo
- Department of Cell Biology, Division of Medicine, Faculty of Medicine, Imperial Centre for Translation and Experimental Medicine, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
| | | | - Dewi Astuti
- Department of Medical and Molecular Genetics
| | - Joel Smith
- Department of Medical and Molecular Genetics
| | - Frank Michelangeli
- School of Clinical and Experimental Medicine, The Medical School School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK and
| | - Guy A Rutter
- Department of Cell Biology, Division of Medicine, Faculty of Medicine, Imperial Centre for Translation and Experimental Medicine, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
| | | |
Collapse
|
59
|
Mondragon A, Davidsson D, Kyriakoudi S, Bertling A, Gomes-Faria R, Cohen P, Rothery S, Chabosseau P, Rutter GA, da Silva Xavier G. Divergent effects of liraglutide, exendin-4, and sitagliptin on beta-cell mass and indicators of pancreatitis in a mouse model of hyperglycaemia. PLoS One 2014; 9:e104873. [PMID: 25119717 PMCID: PMC4132080 DOI: 10.1371/journal.pone.0104873] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Accepted: 06/23/2014] [Indexed: 01/29/2023] Open
Abstract
AIMS Glucagon-like peptide-1 (GLP-1) receptor agonists and dipeptidyl peptidase-4 (DPP4) inhibitors improve glucose tolerance by still incompletely understood mechanisms. Each class of antihyperglycemic drugs has also been proposed to increase pancreatitis risk. Here, we compare systematically the effects of two widely-used GLP-1 analogues, liraglutide and exendin-4, and the DPP4 inhibitor, sitagliptin, in the mouse. METHODS C57BL6 mice were maintained for 131 days on a normal diet (ND) or a diet comprising 60% fat (HFD) before measurements of fasting blood glucose and insulin, and intraperitoneal glucose tolerance. Beta- and alpha- cell volume, and Reg3b immunoreactivity, were measured by immunohistochemical analysis of pancreatic slices. RESULTS Whereas liraglutide (200 µg/kg) and exendin-4 (10 µg/kg) treatment reduced body weight and/or improved glucose tolerance, sitagliptin (10 mg/kg) was without effect on either parameter. Liraglutide caused a sharp reduction in beta-cell mass in both ND and HFD mice, whereas exendin-4 exerted no effect. By contrast, sitagliptin unmasked an action of high fat diet to increase beta-cell mass. Reg3B positive area was augmented by all three agents in normal chow-fed mice, whilst sitagliptin and exendin-4, but not liraglutide, affected this parameter in HFD animals. Correspondingly sitagliptin, but not the GLP-1 analogues, increased circulating amylase levels in ND and HFD mice. CONCLUSIONS Liraglutide improves glucose tolerance in the mouse whilst exerting relatively modest effects on pancreatitis risk. Conversely, exendin-4 and sitagliptin, at doses which exert, respectively, minor or no effects on metabolic parameters, lead to signs of pancreatitis.
Collapse
Affiliation(s)
- Angeles Mondragon
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Daniel Davidsson
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Styliana Kyriakoudi
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Annika Bertling
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Rosa Gomes-Faria
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Patrizia Cohen
- Imperial College Healthcare NHS Trust, Department of Pathology, St. Mary's Hospital, London, United Kingdom
| | | | - Pauline Chabosseau
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Guy A. Rutter
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Gabriela da Silva Xavier
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Faculty of Medicine, Imperial College London, London, United Kingdom
| |
Collapse
|
60
|
Thomsen SK, Gloyn AL. The pancreatic β cell: recent insights from human genetics. Trends Endocrinol Metab 2014; 25:425-34. [PMID: 24986330 PMCID: PMC4229643 DOI: 10.1016/j.tem.2014.05.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 05/02/2014] [Accepted: 05/07/2014] [Indexed: 12/14/2022]
Abstract
Diabetes mellitus is a metabolic disease characterised by relative or absolute pancreatic β cell dysfunction. Genetic variants implicated in disease risk can be identified by studying affected individuals. To understand the mechanisms driving genetic associations, variants must be translated through causative transcripts to biological insights. Studies into the genetic basis of Mendelian forms of diabetes have successfully identified genes involved in both β cell function and pancreatic development. For type 2 diabetes (T2D), genome-wide association studies (GWASs) are uncovering an ever-increasing number of susceptibility variants that exert their effect through β cell dysfunction, but translation to mechanistic understanding has in most cases been slow. Improved annotations of the islet genome and advances in whole-genome and -exome sequencing (WHS and WES) have facilitated recent progress.
Collapse
Affiliation(s)
- Soren K Thomsen
- Oxford Centre for Diabetes, Endocrinology, and Metabolism, University of Oxford, Headington, OX3 7LE, UK
| | - Anna L Gloyn
- Oxford Centre for Diabetes, Endocrinology, and Metabolism, University of Oxford, Headington, OX3 7LE, UK; Oxford National Institute for Health Research (NIHR) Biomedical Research Centre, Churchill Hospital, Headington, OX3 7LE, UK.
| |
Collapse
|
61
|
Zhou Y, Park SY, Su J, Bailey K, Ottosson-Laakso E, Shcherbina L, Oskolkov N, Zhang E, Thevenin T, Fadista J, Bennet H, Vikman P, Wierup N, Fex M, Rung J, Wollheim C, Nobrega M, Renström E, Groop L, Hansson O. TCF7L2 is a master regulator of insulin production and processing. Hum Mol Genet 2014; 23:6419-31. [PMID: 25015099 PMCID: PMC4240194 DOI: 10.1093/hmg/ddu359] [Citation(s) in RCA: 133] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Genome-wide association studies have revealed >60 loci associated with type 2 diabetes (T2D), but the underlying causal variants and functional mechanisms remain largely elusive. Although variants in TCF7L2 confer the strongest risk of T2D among common variants by presumed effects on islet function, the molecular mechanisms are not yet well understood. Using RNA-sequencing, we have identified a TCF7L2-regulated transcriptional network responsible for its effect on insulin secretion in rodent and human pancreatic islets. ISL1 is a primary target of TCF7L2 and regulates proinsulin production and processing via MAFA, PDX1, NKX6.1, PCSK1, PCSK2 and SLC30A8, thereby providing evidence for a coordinated regulation of insulin production and processing. The risk T-allele of rs7903146 was associated with increased TCF7L2 expression, and decreased insulin content and secretion. Using gene expression profiles of 66 human pancreatic islets donors’, we also show that the identified TCF7L2-ISL1 transcriptional network is regulated in a genotype-dependent manner. Taken together, these results demonstrate that not only synthesis of proinsulin is regulated by TCF7L2 but also processing and possibly clearance of proinsulin and insulin. These multiple targets in key pathways may explain why TCF7L2 has emerged as the gene showing one of the strongest associations with T2D.
Collapse
Affiliation(s)
- Yuedan Zhou
- Department of Clinical Sciences, CRC, Lund University, Malmö 20502, Sweden
| | | | - Jing Su
- European Bioinformatics Institute, Functional Genomics, Hinxton, Cambridge CB10 1SD, UK
| | - Kathleen Bailey
- Department of Human Genetics, University of Chicago, IL 60637, USA
| | | | - Liliya Shcherbina
- Department of Clinical Sciences, CRC, Lund University, Malmö 20502, Sweden
| | - Nikolay Oskolkov
- Department of Clinical Sciences, CRC, Lund University, Malmö 20502, Sweden
| | - Enming Zhang
- Department of Clinical Sciences, CRC, Lund University, Malmö 20502, Sweden
| | - Thomas Thevenin
- Department of Clinical Sciences, CRC, Lund University, Malmö 20502, Sweden
| | - João Fadista
- Department of Clinical Sciences, CRC, Lund University, Malmö 20502, Sweden
| | - Hedvig Bennet
- Department of Clinical Sciences, CRC, Lund University, Malmö 20502, Sweden
| | - Petter Vikman
- Department of Clinical Sciences, CRC, Lund University, Malmö 20502, Sweden
| | - Nils Wierup
- Department of Clinical Sciences, CRC, Lund University, Malmö 20502, Sweden
| | - Malin Fex
- Department of Clinical Sciences, CRC, Lund University, Malmö 20502, Sweden
| | - Johan Rung
- Department of Immunology, Genetics and Pathology, Rudbeck Laboratory, Uppsala University, Uppsala 75185, Sweden and
| | - Claes Wollheim
- Department of Clinical Sciences, CRC, Lund University, Malmö 20502, Sweden, Department of Cell Physiology and Metabolism, Université de Genève, University Medical Centre, 1 rue Michel-Servet, Geneva 4 1211, Switzerland
| | - Marcelo Nobrega
- Department of Human Genetics, University of Chicago, IL 60637, USA
| | - Erik Renström
- Department of Clinical Sciences, CRC, Lund University, Malmö 20502, Sweden
| | - Leif Groop
- Department of Clinical Sciences, CRC, Lund University, Malmö 20502, Sweden
| | - Ola Hansson
- Department of Clinical Sciences, CRC, Lund University, Malmö 20502, Sweden,
| |
Collapse
|
62
|
Wagner R, Li J, Kenar E, Kohlbacher O, Machicao F, Häring HU, Fritsche A, Xu G, Lehmann R. Clinical and non-targeted metabolomic profiling of homozygous carriers of Transcription Factor 7-like 2 variant rs7903146. Sci Rep 2014; 4:5296. [PMID: 24925104 PMCID: PMC4055885 DOI: 10.1038/srep05296] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Accepted: 05/28/2014] [Indexed: 12/27/2022] Open
Abstract
An important role of the type 2 diabetes risk variant rs7903146 in TCF7L2 in metabolic actions of various tissues, in particular of the liver, has recently been demonstrated by functional animal studies. Accordingly, the TT diabetes risk allele may lead to currently unknown alterations in human. Our study revealed no differences in the kinetics of glucose, insulin, C-peptide and non-esterified fatty acids during an OGTT in homozygous participants from a German diabetes risk cohort (n = 1832) carrying either the rs7903146 CC (n = 15) or the TT (n = 15) genotype. However, beta-cell function was impaired for TT carriers. Covering more than 4000 metabolite ions the plasma metabolome did not reveal any differences between genotypes. Our study argues against a relevant impact of TCF7L2 rs7903146 on the systemic level in humans, but confirms the role in the pathogenesis of type 2 diabetes in humans as a mechanism impairing insulin secretion.
Collapse
Affiliation(s)
- Robert Wagner
- 1] Division of Endocrinology, Diabetology, Angiology and Nephrology, Department of Internal Medicine 4, University Hospital Tuebingen, Germany [2] Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Zentrum München at the University of Tuebingen, Tuebingen, Germany [3] German Center for Diabetes Research (DZD), Tübingen [4]
| | - Jia Li
- 1] CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China [2]
| | - Erhan Kenar
- 1] Applied Bioinformatics, Center for Bioinformatics, Quantitative Biology Center, and Department of Computer Science, University of Tuebingen, Sand 14, 72076 Tuebingen, Germany [2]
| | - Oliver Kohlbacher
- Applied Bioinformatics, Center for Bioinformatics, Quantitative Biology Center, and Department of Computer Science, University of Tuebingen, Sand 14, 72076 Tuebingen, Germany
| | - Fausto Machicao
- 1] Division of Endocrinology, Diabetology, Angiology and Nephrology, Department of Internal Medicine 4, University Hospital Tuebingen, Germany [2] Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Zentrum München at the University of Tuebingen, Tuebingen, Germany [3] German Center for Diabetes Research (DZD), Tübingen
| | - Hans-Ulrich Häring
- 1] Division of Endocrinology, Diabetology, Angiology and Nephrology, Department of Internal Medicine 4, University Hospital Tuebingen, Germany [2] Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Zentrum München at the University of Tuebingen, Tuebingen, Germany [3] German Center for Diabetes Research (DZD), Tübingen
| | - Andreas Fritsche
- 1] Division of Endocrinology, Diabetology, Angiology and Nephrology, Department of Internal Medicine 4, University Hospital Tuebingen, Germany [2] Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Zentrum München at the University of Tuebingen, Tuebingen, Germany [3] German Center for Diabetes Research (DZD), Tübingen
| | - Guowang Xu
- CAS Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
| | - Rainer Lehmann
- 1] Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Zentrum München at the University of Tuebingen, Tuebingen, Germany [2] German Center for Diabetes Research (DZD), Tübingen [3] Division of Clinical Chemistry and Pathobiochemistry, Department of Internal Medicine 4, University Hospital Tuebingen, Tuebingen, Germany
| |
Collapse
|
63
|
Abstract
PURPOSE OF REVIEW Therapies that increase functional β-cell mass may be the best long-term treatment for diabetes. Significant resources are devoted toward this goal, and progress is occurring at a rapid pace. Here, we summarize recent advances relevant to human β-cell regeneration. RECENT FINDINGS New β-cells arise from proliferation of pre-existing β-cells or transdifferentiation from other cell types. In addition, dedifferentiated β-cells may populate islets in diabetes, possibly representing a pool of cells that could redifferentiate into functional β-cells. Advances in finding strategies to drive β-cell proliferation include new insight into proproliferative factors, both circulating and local, and elements intrinsic to the β-cell, such as cell cycle machinery and regulation of gene expression through epigenetic modification and noncoding RNAs. Controversy continues in the arena of generation of β-cells by transdifferentiation from exocrine, ductal, and alpha cells, with studies producing both supporting and opposing data. Progress has been made in redifferentiation of β-cells that have lost expression of β-cell markers. SUMMARY Although significant progress has been made, and promising avenues exist, more work is needed to achieve the goal of β-cell regeneration as a treatment for diabetes.
Collapse
Affiliation(s)
- Agata Jurczyk
- University of Massachusetts Medical School, Diabetes Center of Excellence, Worcester, Massachusetts, USA
| | | | | |
Collapse
|
64
|
Bernal-Mizrachi E, Kulkarni RN, Scott DK, Mauvais-Jarvis F, Stewart AF, Garcia-Ocaña A. Human β-cell proliferation and intracellular signaling part 2: still driving in the dark without a road map. Diabetes 2014; 63:819-31. [PMID: 24556859 PMCID: PMC3931400 DOI: 10.2337/db13-1146] [Citation(s) in RCA: 141] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Enhancing β-cell proliferation is a major goal for type 1 and type 2 diabetes research. Unraveling the network of β-cell intracellular signaling pathways that promote β-cell replication can provide the tools to address this important task. In a previous Perspectives in Diabetes article, we discussed what was known regarding several important intracellular signaling pathways in rodent β-cells, including the insulin receptor substrate/phosphatidylinositol-3 kinase/Akt (IRS-PI3K-Akt) pathways, glycogen synthase kinase-3 (GSK3) and mammalian target of rapamycin (mTOR) S6 kinase pathways, protein kinase Cζ (PKCζ) pathways, and their downstream cell-cycle molecular targets, and contrasted that ample knowledge to the small amount of complementary data on human β-cell intracellular signaling pathways. In this Perspectives, we summarize additional important information on signaling pathways activated by nutrients, such as glucose; growth factors, such as epidermal growth factor, platelet-derived growth factor, and Wnt; and hormones, such as leptin, estrogen, and progesterone, that are linked to rodent and human β-cell proliferation. With these two Perspectives, we attempt to construct a brief summary of knowledge for β-cell researchers on mitogenic signaling pathways and to emphasize how little is known regarding intracellular events linked to human β-cell replication. This is a critical aspect in the long-term goal of expanding human β-cells for the prevention and/or cure of type 1 and type 2 diabetes.
Collapse
Affiliation(s)
- Ernesto Bernal-Mizrachi
- Division of Metabolism, Endocrinology, and Diabetes, University of Michigan, and U.S. Department of Veterans Affairs Ann Arbor Healthcare System, Ann Arbor, MI
- Corresponding authors: Ernesto Bernal-Mizrachi, , and Adolfo Garcia-Ocaña,
| | - Rohit N. Kulkarni
- Islet Cell Biology and Regenerative Medicine, Joslin Diabetes Center, Harvard Medical School, Boston, MA
- Department of Medicine, Harvard Medical School, Boston, MA
| | - Donald K. Scott
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Franck Mauvais-Jarvis
- Division of Endocrinology and Metabolism, Tulane University School of Medicine and Health Sciences Center, New Orleans, LA
| | - Andrew F. Stewart
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Adolfo Garcia-Ocaña
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
- Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, NY
- Corresponding authors: Ernesto Bernal-Mizrachi, , and Adolfo Garcia-Ocaña,
| |
Collapse
|
65
|
Takamoto I, Kubota N, Nakaya K, Kumagai K, Hashimoto S, Kubota T, Inoue M, Kajiwara E, Katsuyama H, Obata A, Sakurai Y, Iwamoto M, Kitamura T, Ueki K, Kadowaki T. TCF7L2 in mouse pancreatic beta cells plays a crucial role in glucose homeostasis by regulating beta cell mass. Diabetologia 2014; 57:542-53. [PMID: 24317852 DOI: 10.1007/s00125-013-3131-6] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Accepted: 11/11/2013] [Indexed: 12/13/2022]
Abstract
AIMS/HYPOTHESIS Common genetic variations of the transcription factor 7-like 2 gene (encoded by TCF7L2), one of the T cell factor/lymphoid enhancer-binding factor transcription factors for the converging wingless-type MMTV integration site family (Wnt)/β-catenin signalling pathway, are known to be associated with type 2 diabetes. Individuals with at-risk alleles of TCF7L2 exhibit impaired insulin secretion. Although previous studies using animal models have revealed the existence of a relationship between the Wnt/β-catenin signalling pathway and glucose homeostasis, it remains unclear whether TCF7L2 in the pancreatic beta cells might be causally involved in insulin secretion in vivo. In this study, we investigated the role of TCF7L2 expressed in the pancreatic beta cells in glucose homeostasis. METHODS Three independent groups of genetically engineered mice (DN mice) were generated, in which expression of the dominant-negative form of Tcf7l2 was driven under a rat insulin promoter. Phenotypes of both adult and newborn mice were evaluated. The levels of genes and proteins expressed in isolated islets were determined by reverse transcription-quantitative PCR and western blot analysis, respectively. RESULTS Adult DN mice showed impaired glucose tolerance and decreased insulin secretion in both oral and intraperitoneal glucose tolerance tests. Marked reduction of the beta cell area and whole-pancreas insulin content was observed in both the adult and newborn DN mice. Islets from the DN mice showed decreased gene expressions of Ccnd1, Ccnd2, Irs1, Irs2, Ins1, Ins2 and Mafa, consistent with the deleterious effects of the dominant-negative form of Tcf7l2 on beta cell proliferation and insulin production. CONCLUSIONS/INTERPRETATION TCF7L2 expressed in the pancreatic beta cells plays a crucial role in glucose metabolism through regulation of the beta cell mass.
Collapse
Affiliation(s)
- Iseki Takamoto
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
66
|
Wang X, Lei XG, Wang J. Malondialdehyde regulates glucose-stimulated insulin secretion in murine islets via TCF7L2-dependent Wnt signaling pathway. Mol Cell Endocrinol 2014; 382:8-16. [PMID: 24035868 DOI: 10.1016/j.mce.2013.09.003] [Citation(s) in RCA: 209] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Revised: 08/30/2013] [Accepted: 09/03/2013] [Indexed: 11/29/2022]
Abstract
Evidence showed strong relations between malondialdehyde (MDA) levels and different pathological stages of diabetes. Here, an explicit system with freshly isolated islets and precisely controlled MDA gradient was employed to investigate the physiological effect of MDA on GSIS. Promoter analysis, pathway mapping, Q-PCR profiling, and siRNA verification were performed to clarify the intracellular signaling pathways. MDA at a moderately high level (5 and 10μM) promoted GSIS and accompanied with ATP/ADP ratio, cytosolic Ca(2+) level, and key regulators (GK, GLUT2, PDX1, and UCP2) changes in islets. Both upstream (PI3K and p-AKT) and downstream (TCF7L2 and TCF7) factors of Wnt pathway showed greatest changes. Knockdown of TCF7L2 blocked the MDA-induced GSIS elevation. These results indicated that MDA acted as a signaling messenger and regulated islet GSIS mainly through Wnt pathway. Therefore, the elevated MDA level and up-regulated Wnt signaling pathway could be an etiological factor in the development of hyperinsulinemia and type 2 diabetes.
Collapse
Affiliation(s)
- Xinhui Wang
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, Guangdong 510006, China; Animal Science Department, Cornell University, Ithaca, NY 14853, USA
| | - Xin Gen Lei
- Animal Science Department, Cornell University, Ithaca, NY 14853, USA.
| | - Jufang Wang
- School of Bioscience and Bioengineering, South China University of Technology, Guangzhou, Guangdong 510006, China.
| |
Collapse
|
67
|
Basile KJ, Johnson ME, Xia Q, Grant SFA. Genetic susceptibility to type 2 diabetes and obesity: follow-up of findings from genome-wide association studies. Int J Endocrinol 2014; 2014:769671. [PMID: 24719615 PMCID: PMC3955626 DOI: 10.1155/2014/769671] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Revised: 01/17/2014] [Accepted: 01/20/2014] [Indexed: 12/13/2022] Open
Abstract
Elucidating the underlying genetic variations influencing various complex diseases is one of the major challenges currently facing clinical genetic research. Although these variations are often difficult to uncover, approaches such as genome-wide association studies (GWASs) have been successful at finding statistically significant associations between specific genomic loci and disease susceptibility. GWAS has been especially successful in elucidating genetic variants that influence type 2 diabetes (T2D) and obesity/body mass index (BMI). Specifically, several GWASs have confirmed that a variant in transcription factor 7-like 2 (TCF7L2) confers risk for T2D, while a variant in fat mass and obesity-associated protein (FTO) confers risk for obesity/BMI; indeed both of these signals are considered the most statistically associated loci discovered for these respective traits to date. The discovery of these two key loci in this context has been invaluable for providing novel insight into mechanisms of heritability and disease pathogenesis. As follow-up studies of TCF7L2 and FTO have typically lead the way in how to follow up a GWAS discovery, we outline what has been learned from such investigations and how they have implications for the myriad of other loci that have been subsequently reported in this disease context.
Collapse
Affiliation(s)
- Kevin J. Basile
- Division of Human Genetics, The Children's Hospital of Philadelphia Research Institute, 34th and Civic Center Boulevard, Philadelphia, PA 19104, USA
| | - Matthew E. Johnson
- Division of Human Genetics, The Children's Hospital of Philadelphia Research Institute, 34th and Civic Center Boulevard, Philadelphia, PA 19104, USA
| | - Qianghua Xia
- Division of Human Genetics, The Children's Hospital of Philadelphia Research Institute, 34th and Civic Center Boulevard, Philadelphia, PA 19104, USA
| | - Struan F. A. Grant
- Division of Human Genetics, The Children's Hospital of Philadelphia Research Institute, 34th and Civic Center Boulevard, Philadelphia, PA 19104, USA
- Center for Applied Genomics, The Children's Hospital of Philadelphia Research Institute, 34th and Civic Center Boulevard, Philadelphia, PA 19104, USA
- Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- 1216F Children's Hospital of Philadelphia Research Institute, 34th and Civic Center Boulevard, Philadelphia, PA 19104, USA
- *Struan F. A. Grant:
| |
Collapse
|
68
|
Lee YS, Jun HS. Anti-diabetic actions of glucagon-like peptide-1 on pancreatic beta-cells. Metabolism 2014; 63:9-19. [PMID: 24140094 DOI: 10.1016/j.metabol.2013.09.010] [Citation(s) in RCA: 199] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 09/05/2013] [Accepted: 09/14/2013] [Indexed: 12/11/2022]
Abstract
Glucagon-like peptide-1 (GLP-1), an incretin hormone, is released from intestinal L-cells in response to nutrients. GLP-1 lowers blood glucose levels by stimulating insulin secretion from pancreatic beta-cells in a glucose-dependent manner. In addition, GLP-1 slows gastric emptying, suppresses appetite, reduces plasma glucagon, and stimulates glucose disposal, which are beneficial for glucose homeostasis. Therefore, incretin-based therapies such as GLP-1 receptor agonists and inhibitors of dipeptidyl peptidase IV, an enzyme which inactivates GLP-1, have been developed for treatment of diabetes. This review outlines our knowledge of the actions of GLP-1 on insulin secretion and biosynthesis, beta-cell proliferation and regeneration, and protection against beta-cell damage, as well as the involvement of recently discovered signaling pathways of GLP-1 action, mainly focusing on pancreatic beta-cells.
Collapse
Affiliation(s)
- Young-Sun Lee
- Lee Gil Ya Cancer and Diabetes Institute, Gachon University, 7-45 Songdo-dong, Yeonsu-ku, Incheon 406-840, South Korea
| | | |
Collapse
|
69
|
Rutter GA, Hodson DJ. Minireview: intraislet regulation of insulin secretion in humans. Mol Endocrinol 2013; 27:1984-95. [PMID: 24243488 PMCID: PMC5426601 DOI: 10.1210/me.2013-1278] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Accepted: 10/23/2013] [Indexed: 12/25/2022] Open
Abstract
The higher organization of β-cells into spheroid structures termed islets of Langerhans is critical for the proper regulation of insulin secretion. Thus, rodent β-cells form a functional syncytium that integrates and propagates information encoded by secretagogues, producing a "gain-of-function" in hormone release through the generation of coordinated cell-cell activity. By contrast, human islets possess divergent topology, and this may have repercussions for the cell-cell communication pathways that mediate the population dynamics underlying the intraislet regulation of insulin secretion. This is pertinent for type 2 diabetes mellitus pathogenesis, and its study in rodent models, because environmental and genetic factors may converge on these processes in a species-specific manner to precipitate the defective insulin secretion associated with glucose intolerance. The aim of the present minireview is therefore to discuss the structural and functional underpinnings that influence insulin secretion from human islets, and the possibility that dyscoordination between individual β-cells may play an important role in some forms of type 2 diabetes mellitus.
Collapse
Affiliation(s)
- Guy A Rutter
- Section Cell Biology, Department of Medicine, Imperial College London, London SW7 2AZ, United Kingdom. ; or Professor Guy A. Rutter, Section of Cell Biology, Department of Medicine, Imperial College London, London SW7 2AZ, United Kingdom. E-mail:
| | | |
Collapse
|
70
|
Abstract
Type 2 diabetes is a global pandemic for which there is currently no disease-modifying treatment. New and targeted therapeutics are greatly needed, but progress in identifying novel targets for therapeutic intervention is severely hampered by poor understanding of disease pathogenesis. Over the past 6 years, the success of genome-wide association studies has led to an unprecedented increase in the number of loci robustly associating with type 2 diabetes risk. Each of these signals offers the opportunity to uncover biological insights into disease pathogenesis, which, if harnessed effectively, hold the promise to deliver new pathways for therapeutic intervention, strategies for patient stratification, and potentially, biomarkers for identifying those at greatest risk of developing diabetes. We review the progress that has been made and the approaches being adopted and discuss the inherent challenges in moving from association signals, which largely map to poorly annotated sequence, to transcripts, mechanisms, and disease biology.
Collapse
Affiliation(s)
- Hui Jin Ng
- Oxford Centre for Diabetes, Endocrinology & Metabolism, Churchill Hospital, University of Oxford, Oxford, OX3 7LE, UK,
| | | |
Collapse
|
71
|
Pasek RC, Gannon M. Advancements and challenges in generating accurate animal models of gestational diabetes mellitus. Am J Physiol Endocrinol Metab 2013; 305:E1327-38. [PMID: 24085033 PMCID: PMC4073988 DOI: 10.1152/ajpendo.00425.2013] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The maintenance of glucose homeostasis during pregnancy is critical to the health and well-being of both the mother and the developing fetus. Strikingly, approximately 7% of human pregnancies are characterized by insufficient insulin production or signaling, resulting in gestational diabetes mellitus (GDM). In addition to the acute health concerns of hyperglycemia, women diagnosed with GDM during pregnancy have an increased incidence of complications during pregnancy as well as an increased risk of developing type 2 diabetes (T2D) later in life. Furthermore, children born to mothers diagnosed with GDM have increased incidence of perinatal complications, including hypoglycemia, respiratory distress syndrome, and macrosomia, as well as an increased risk of being obese or developing T2D as adults. No single environmental or genetic factor is solely responsible for the disease; instead, a variety of risk factors, including weight, ethnicity, genetics, and family history, contribute to the likelihood of developing GDM, making the generation of animal models that fully recapitulate the disease difficult. Here, we discuss and critique the various animal models that have been generated to better understand the etiology of diabetes during pregnancy and its physiological impacts on both the mother and the fetus. Strategies utilized are diverse in nature and include the use of surgical manipulation, pharmacological treatment, nutritional manipulation, and genetic approaches in a variety of animal models. Continued development of animal models of GDM is essential for understanding the consequences of this disease as well as providing insights into potential treatments and preventative measures.
Collapse
Affiliation(s)
- Raymond C Pasek
- Tennessee Valley Healthcare System, Department of Veteran Affairs, Nashville, Tennessee
| | | |
Collapse
|
72
|
Schwenk RW, Vogel H, Schürmann A. Genetic and epigenetic control of metabolic health. Mol Metab 2013; 2:337-47. [PMID: 24327950 PMCID: PMC3854991 DOI: 10.1016/j.molmet.2013.09.002] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 09/09/2013] [Accepted: 09/13/2013] [Indexed: 02/06/2023] Open
Abstract
Obesity is characterized as an excess accumulation of body fat resulting from a positive energy balance. It is the major risk factor for type 2 diabetes (T2D). The evidence for familial aggregation of obesity and its associated metabolic diseases is substantial. To date, about 150 genetic loci identified in genome-wide association studies (GWAS) are linked with obesity and T2D, each accounting for only a small proportion of the predicted heritability. However, the percentage of overall trait variance explained by these associated loci is modest (~5-10% for T2D, ~2% for BMI). The lack of powerful genetic associations suggests that heritability is not entirely attributable to gene variations. Some of the familial aggregation as well as many of the effects of environmental exposures, may reflect epigenetic processes. This review summarizes our current knowledge on the genetic basis to individual risk of obesity and T2D, and explores the potential role of epigenetic contribution.
Collapse
Key Words
- ADCY3, adenylate cyclase 3
- AQP9, aquaporin 9
- BDNF, brain-derived neurotrophic factor
- CDKAL1, CDK5 regulatory subunit associated protein 1-like 1
- CPEB4, cytoplasmic polyadenylation element binding protein 4
- DUSP22, dual specificity phosphatase 22
- DUSP8, dual specificity phosphatase 8
- Epigenetics
- GALNT10, UDP-N-acetyl-alpha-d-galactosamine:polypeptide N-acetylgalactosaminyltransferase 10 (GalNAc-T10)
- GIPR, gastric inhibitory polypeptide receptor
- GNPDA2, glucosamine-6-phosphate deaminase 2
- GP2, glycoprotein 2 (zymogen granule membrane)
- GWAS
- HIPK3, homeodomain interacting protein kinase 3
- IFI16, interferon, gamma-inducible protein 16
- KCNQ1, potassium voltage-gated channel, KQT-like subfamily, member 1
- KLHL32, kelch-like family member 32
- LEPR, leptin receptor
- MAP2K4, mitogen-activated protein kinase kinase 4
- MAP2K5, mitogen-activated protein kinase kinase 5
- MIR148A, microRNA 148a
- MMP9, matrix metallopeptidase 9 (gelatinase B, 92 kDa gelatinase, 92 kDa type IV collagenase)
- MNDA, myeloid cell nuclear differentiation antigen
- NFE2L3, nuclear factor, erythroid 2-like 3
- Obesity
- PACS1, phosphofurin acidic cluster sorting protein 1
- PAX6, paired box gene 6
- PCSK1, proprotein convertase subtilisin/kexin type 1
- PGC1α, peroxisome proliferative activated receptor, gamma, coactivator 1 alpha, PM2OD1
- PRKCH, protein kinase C, eta
- PRKD1, protein kinase D1
- PRKG1, protein kinase, cGMP-dependent, type I
- Positional cloning
- QPCTL, glutaminyl-peptide cyclotransferase-like
- RBJ, DnaJ (Hsp40) homolog, subfamily C, member 27
- RFC5, replication factor C (activator 1) 5
- RMST, rhabdomyosarcoma 2 associated transcript (non-protein coding)
- SEC16B, SEC16 homolog B
- TFAP2B, transcription factor AP-2 beta (activating enhancer binding protein 2 beta)
- TNNI3, troponin I type 3 (cardiac)
- TNNT1, troponin T type 1 (skeletal, slow)
- Type 2 diabetes
Collapse
Affiliation(s)
| | | | - Annette Schürmann
- Corresponding author. Tel.: +49 33200 882368; fax: +49 33200 882334.
| |
Collapse
|
73
|
Abstract
In healthy individuals, insulin resistance is associated with physiological conditions such as pregnancy or body weight gain and triggers an increase in beta cell number and insulin secretion capacity to preserve normoglycaemia. Failure of this beta cell compensation capacity is a fundamental cause of diabetic hyperglycaemia. Incomplete understanding of the molecular mechanisms controlling the plasticity of adult beta cells mechanisms and how these cells fail during the pathogenesis of diabetes strongly limits the ability to develop new beta cell-specific therapies. Here, current knowledge of the signalling pathways controlling beta cell plasticity is reviewed, and possible directions for future research are discussed.
Collapse
Affiliation(s)
- B Thorens
- Center for Integrative Genomics, University of Lausanne, Switzerland.
| |
Collapse
|
74
|
Ordelheide AM, Gerst F, Rothfuss O, Heni M, Haas C, Thielker I, Herzberg-Schäfer S, Böhm A, Machicao F, Ullrich S, Stefan N, Fritsche A, Häring HU, Staiger H. Nor-1, a novel incretin-responsive regulator of insulin genes and insulin secretion. Mol Metab 2013; 2:243-55. [PMID: 24044104 DOI: 10.1016/j.molmet.2013.06.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 06/07/2013] [Accepted: 06/10/2013] [Indexed: 01/09/2023] Open
Abstract
B-cell failure at the onset of type 2 diabetes is caused by a decline in β-cell function in the postprandial state and loss of pancreatic β-cell mass. Recently, we showed an association between increased insulin secretion and a single nucleotide polymorphism (SNP), SNP rs12686676, in the NR4A3 gene locus encoding the nuclear receptor Nor-1. Nor-1 is expressed in β-cells, however, not much is known about its function with regard to insulin gene expression and insulin secretion. Nor-1 is induced in a glucose-/incretin-dependent manner via the PKA pathway and directly induces insulin gene expression. Additionally, it stimulates insulin secretion possibly via regulation of potentially important genes in insulin exocytosis. Moreover, we show that the minor allele of NR4A3 SNP rs12686676 fully rescues incretin resistance provoked by a well-described polymorphism in TCF7L2. Thus, Nor-1 represents a promising new target for pharmacological intervention to fight diabetes.
Collapse
Affiliation(s)
- Anna-Maria Ordelheide
- Department of Internal Medicine, Division of Endocrinology, Diabetology, Angiology, Nephrology and Clinical Chemistry, University Hospital Tübingen, Germany ; Institute for Diabetes Research and Metabolic Diseases of the Helmholz Centre Munich at the University of Tübingen, Germany ; German Center for Diabetes Research (DZD), Neuherberg, Germany
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
75
|
Abstract
Incretin peptides, principally GLP-1 and GIP, regulate islet hormone secretion, glucose concentrations, lipid metabolism, gut motility, appetite and body weight, and immune function, providing a scientific basis for utilizing incretin-based therapies in the treatment of type 2 diabetes. Activation of GLP-1 and GIP receptors also leads to nonglycemic effects in multiple tissues, through direct actions on tissues expressing incretin receptors and indirect mechanisms mediated through neuronal and endocrine pathways. Here we contrast the pharmacology and physiology of incretin hormones and review recent advances in mechanisms coupling incretin receptor signaling to pleiotropic metabolic actions in preclinical studies. We discuss whether mechanisms identified in preclinical studies have potential translational relevance for the treatment of human disease and highlight controversies and uncertainties in incretin biology that require resolution in future studies.
Collapse
Affiliation(s)
- Jonathan E Campbell
- Department of Medicine, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, University of Toronto, Toronto, ON M5G 1X5, Canada
| | - Daniel J Drucker
- Department of Medicine, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, University of Toronto, Toronto, ON M5G 1X5, Canada.
| |
Collapse
|
76
|
da Silva Xavier G, Bellomo EA, McGinty JA, French PM, Rutter GA. Animal models of GWAS-identified type 2 diabetes genes. J Diabetes Res 2013; 2013:906590. [PMID: 23710470 PMCID: PMC3654344 DOI: 10.1155/2013/906590] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Accepted: 03/18/2013] [Indexed: 02/07/2023] Open
Abstract
More than 65 loci, encoding up to 500 different genes, have been implicated by genome-wide association studies (GWAS) as conferring an increased risk of developing type 2 diabetes (T2D). Whilst mouse models have in the past been central to understanding the mechanisms through which more penetrant risk genes for T2D, for example, those responsible for neonatal or maturity-onset diabetes of the young, only a few of those identified by GWAS, notably TCF7L2 and ZnT8/SLC30A8, have to date been examined in mouse models. We discuss here the animal models available for the latter genes and provide perspectives for future, higher throughput approaches towards efficiently mining the information provided by human genetics.
Collapse
Affiliation(s)
- Gabriela da Silva Xavier
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, London SW7 2AZ, UK
| | - Elisa A. Bellomo
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, London SW7 2AZ, UK
| | - James A. McGinty
- Biophotonics Section, Department of Physics, Imperial College London, London SW7 2AZ, UK
| | - Paul M. French
- Biophotonics Section, Department of Physics, Imperial College London, London SW7 2AZ, UK
| | - Guy A. Rutter
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, London SW7 2AZ, UK
| |
Collapse
|
77
|
Sun X, Song M, Bai R, Cheng S, Xing Y, Yuan H, Wang P, Zhou L. Ileal interposition surgery-induced improvement of hyperglycemia and insulin resistance in Goto-Kakizaki rats by upregulation of TCF7L2 expression. Exp Ther Med 2013; 5:1511-1515. [PMID: 23737909 PMCID: PMC3671895 DOI: 10.3892/etm.2013.998] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2012] [Accepted: 03/05/2013] [Indexed: 12/20/2022] Open
Abstract
The aim of this study was to investigate the effects of ileal interposition (IT) on glucose and insulin resistance (IR) in type 2 diabetic mellitus (T2DM), and the role of T-cell factor 7-like 2 (TCF7L2), formerly known as TCF4, in the downregulation of hyperglycemia following IT. Goto-Kakizaki (GK) rats subjected to IT surgery (GK-IT group), GK rats subjected to sham surgery (GK-Sham group) and Wistar (WS) rats subjected to sham surgery (WS-Sham group) were investigated in this study. Fasting plasma glucose, body weight, food intake per 1 kg body weight, insulin and a homeostasis model assessment of insulin resistance (HOMA-IR) were measured pre- and post-surgery. The rats were euthanized 28 days post-surgery and the pancreas of each rat was dissected. The expression levels of TCF7L2 mRNA and protein were analyzed by quantitative RT-PCR and western blotting, respectively. Our results revealed that IT improved both fasting plasma glucose levels and IR in GK rats by upregulating the expression of the TCF7L2 protein. IT provides a valuable therapeutic option for patients with T2DM. Upregulation of TCF7L2 protein expression may be a possible mechanism underlying the improvement of T2DM following IT.
Collapse
Affiliation(s)
- Xu Sun
- Department of General Surgery, Beijing Tiantan Hospital, Capital Medical University, Beijing 100050, P.R. China
| | | | | | | | | | | | | | | |
Collapse
|
78
|
Affiliation(s)
- Marcelo A Nobrega
- Department of Human Genetics, University of Chicago, Chicago, Illinois, USA.
| |
Collapse
|
79
|
Abstract
Human genetics is revealing ever more variants that influence propensity to common diseases, but progress in translating these discoveries into the biological mechanisms responsible for predisposition continues to lag behind. A recent paper in Cell (Boj et al., 2012) using rodent models to examine how diabetes-associated variants near TCF7L2 perturb metabolic regulation provides surprising results.
Collapse
Affiliation(s)
- Mark I McCarthy
- Oxford Centre for Diabetes, Endocrinology, and Metabolism, University of Oxford, Churchill Hospital, Old Road, Headington, Oxford OX3 7LE, UK.
| | | | | |
Collapse
|
80
|
Abstract
The incretin hormones glucagon-like peptide-1 and glucose-dependent insulinotropic peptide are secreted by enteroendocrine cells and augment glucose-induced insulin secretion in response to food ingestion in a glucose-dependent manner. This mechanism forms the basis for incretin-based therapies in type 2 diabetes. However, the insulinotropic effect of incretins is diminished in type 2 diabetic patients, due in part to reduced expression of incretin receptors as a consequence of glucotoxicity. In this issue of Diabetologia, Kang et al (DOI: 10.1007/s00125-012-2776-x ) provide evidence that in addition to glucotoxicity, lipotoxicity also affects incretin receptor expression and signalling in insulin-secreting cells and isolated islets. In animal models of diabetes, the authors show that co-administration of a lipid-lowering drug with a dipeptidyl peptidase-4 inhibitor or a glucagon-like peptide-1 agonist improved glucose tolerance and beta cell mass. These novel findings provide convincing support for the notion that restoring normal circulating lipid levels in type 2 diabetes might help improve the efficacy of incretin-based therapies.
Collapse
Affiliation(s)
- V Poitout
- Montreal Diabetes Research Center, CRCHUM, Technopôle Angus, 2901 Rachel Est, Montréal, QC, Canada.
| |
Collapse
|
81
|
Shu L, Zien K, Gutjahr G, Oberholzer J, Pattou F, Kerr-Conte J, Maedler K. TCF7L2 promotes beta cell regeneration in human and mouse pancreas. Diabetologia 2012; 55:3296-307. [PMID: 22945304 DOI: 10.1007/s00125-012-2693-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Accepted: 07/17/2012] [Indexed: 11/25/2022]
Abstract
AIMS/HYPOTHESIS Diabetes is characterised by loss and dysfunction of the beta cell. A major goal of diabetes therapy is to promote the formation of new beta cells. Polymorphisms of T cell factor 7-like 2 (TCF7L2) are associated with type 2 diabetes, negatively regulating beta cell survival and function. Here, we provide evidence for a role of TCF7L2 in beta cell proliferation and regeneration. METHODS Pancreatic sections from three mouse models (high-fat diet, exendin-4 and streptozotocin-treated mice) and from healthy individuals and patients with type 2 diabetes were used to investigate the association of beta cell regeneration and TCF7L2 levels. To analyse a direct effect of TCF7L2 on duct cell to beta cell conversion, TCF7L2 was overexpressed in isolated exocrine cells. RESULTS TCF7L2 levels correlated with beta cell compensation during high-fat diet feeding. TCF7L2 was increased together with pancreatic duct cell proliferation and differentiation. Small islet-like cell clusters (ICCs) that contained TCF7L2 originated in the vicinity of the ductal epithelium. In human isolated exocrine tissue, TCF7L2 overexpression induced proliferation of pancreatic duct cells and ICC formation next to duct cells, an effect dependent on the JAK2/STAT3 pathway. CONCLUSIONS/INTERPRETATION The present study demonstrates that TCF7L2 overexpression fosters beta cell regeneration. Our findings imply correlation of TCF7L2 levels and new beta cell formation.
Collapse
Affiliation(s)
- L Shu
- Centre for Biomolecular Interactions Bremen, University of Bremen, Leobener Strasse NW2, Bremen, Germany
| | | | | | | | | | | | | |
Collapse
|
82
|
Abstract
The genomes of many species have now been completely sequenced including human and mouse. Great progress has been made in understanding the complex genetics that underlie diabetes and obesity in human populations. One of the current challenges is the functional identification and characterization of the genes within loci that are being mapped. There are many approaches to this problem and this review outlines the valuable role that the mouse can play. We outline the mouse resources that are available to the research community, including knockouts with conditional potential for every gene, and the efforts of the International Mouse Phenotyping Consortium to attach phenotype information to these genes. We also briefly consider the potential of TALEN technology to tailor-make new mouse models of specific mutations discovered in humans. Finally, we consider the recent progress in characterizing the GWAS genes FTO, TCF7L2, CDKAL1, and SLC30A8 in engineered mouse models.
Collapse
Affiliation(s)
- Fiona McMurray
- MRC Harwell, Mammalian Genetics Unit, Medical Research Council, Harwell Science and Innovation Campus, Oxfordshire, OX11 0RD UK
| | - Lee Moir
- MRC Harwell, Mammalian Genetics Unit, Medical Research Council, Harwell Science and Innovation Campus, Oxfordshire, OX11 0RD UK
| | - Roger D. Cox
- MRC Harwell, Mammalian Genetics Unit, Medical Research Council, Harwell Science and Innovation Campus, Oxfordshire, OX11 0RD UK
| |
Collapse
|
83
|
Renström E. Impact of transcription factor 7-like 2 (TCF7L2) on pancreatic islet function and morphology in mice and men. Diabetologia 2012; 55:2559-2561. [PMID: 22864463 PMCID: PMC3433659 DOI: 10.1007/s00125-012-2659-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2012] [Accepted: 06/22/2012] [Indexed: 12/22/2022]
Abstract
Common genetic variations in the gene encoding transcription factor 7-like 2 (TCF7L2) reveal the strongest association with type 2-diabetes known to date. These lead to impaired insulin production and output, but the mechanisms of disease remain incompletely known. In this issue of Diabetologia, two publications provide new insights into TCF7L2-dependent diabetes.
Collapse
Affiliation(s)
- E Renström
- Lund University Diabetes Center, Inga-Marie Nilssons gata 53 floor 3, 205 02, Malmö, Sweden.
| |
Collapse
|