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Spijker HS, Song H, Ellenbroek JH, Roefs MM, Engelse MA, Bos E, Koster AJ, Rabelink TJ, Hansen BC, Clark A, Carlotti F, de Koning EJP. Loss of β-Cell Identity Occurs in Type 2 Diabetes and Is Associated With Islet Amyloid Deposits. Diabetes 2015; 64:2928-38. [PMID: 25918235 DOI: 10.2337/db14-1752] [Citation(s) in RCA: 121] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 04/10/2015] [Indexed: 01/06/2023]
Abstract
Loss of pancreatic islet β-cell mass and β-cell dysfunction are central in the development of type 2 diabetes (T2DM). We recently showed that mature human insulin-containing β-cells can convert into glucagon-containing α-cells ex vivo. This loss of β-cell identity was characterized by the presence of β-cell transcription factors (Nkx6.1, Pdx1) in glucagon(+) cells. Here, we investigated whether the loss of β-cell identity also occurs in vivo, and whether it is related to the presence of (pre)diabetes in humans and nonhuman primates. We observed an eight times increased frequency of insulin(+) cells coexpressing glucagon in donors with diabetes. Up to 5% of the cells that were Nkx6.1(+) but insulin(-) coexpressed glucagon, which represents a five times increased frequency compared with the control group. This increase in bihormonal and Nkx6.1(+)glucagon(+)insulin(-) cells was also found in islets of diabetic macaques. The higher proportion of bihormonal cells and Nkx6.1(+)glucagon(+)insulin(-) cells in macaques and humans with diabetes was correlated with the presence and extent of islet amyloidosis. These data indicate that the loss of β-cell identity occurs in T2DM and could contribute to the decrease of functional β-cell mass. Maintenance of β-cell identity is a potential novel strategy to preserve β-cell function in diabetes.
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Affiliation(s)
- H Siebe Spijker
- Department of Nephrology, Leiden University Medical Center, Leiden, the Netherlands
| | - Heein Song
- Department of Nephrology, Leiden University Medical Center, Leiden, the Netherlands Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
| | - Johanne H Ellenbroek
- Department of Nephrology, Leiden University Medical Center, Leiden, the Netherlands
| | - Maaike M Roefs
- Department of Nephrology, Leiden University Medical Center, Leiden, the Netherlands
| | - Marten A Engelse
- Department of Nephrology, Leiden University Medical Center, Leiden, the Netherlands
| | - Erik Bos
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, the Netherlands
| | - Abraham J Koster
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, the Netherlands
| | - Ton J Rabelink
- Department of Nephrology, Leiden University Medical Center, Leiden, the Netherlands
| | - Barbara C Hansen
- Departments of Internal Medicine and Pediatrics, Morsani College of Medicine, University of South Florida, Tampa, FL
| | - Anne Clark
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford, U.K
| | - Françoise Carlotti
- Department of Nephrology, Leiden University Medical Center, Leiden, the Netherlands
| | - Eelco J P de Koning
- Department of Nephrology, Leiden University Medical Center, Leiden, the Netherlands Hubrecht Institute, Utrecht, the Netherlands
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52
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Do OH, Low JT, Thorn P. Lepr(db) mouse model of type 2 diabetes: pancreatic islet isolation and live-cell 2-photon imaging of intact islets. J Vis Exp 2015:e52632. [PMID: 25992768 DOI: 10.3791/52632] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Type 2 diabetes is a chronic disease affecting 382 million people in 2013, and is expected to rise to 592 million by 2035 (1). During the past 2 decades, the role of beta-cell dysfunction in type 2 diabetes has been clearly established (2). Research progress has required methods for the isolation of pancreatic islets. The protocol of the islet isolation presented here shares many common steps with protocols from other groups, with some modifications to improve the yield and quality of isolated islets from both the wild type and diabetic Lepr(db) (db/db) mice. A live-cell 2-photon imaging method is then presented that can be used to investigate the control of insulin secretion within islets.
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Affiliation(s)
- Oanh H Do
- School of Biomedical Sciences, The University of Queensland
| | - Jiun T Low
- School of Biomedical Sciences, The University of Queensland
| | - Peter Thorn
- School of Biomedical Sciences, The University of Queensland;
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Orr C, Stratton J, Rao I, Al-Sayed M, Smith C, El-Shahawy M, Dafoe D, Mullen Y, Al-Abdullah I, Kandeel F. Quantifying Insulin Therapy Requirements to Preserve Islet Graft Function Following Islet Transplantation. Cell Transplant 2015; 25:83-95. [PMID: 25853639 DOI: 10.3727/096368915x687958] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
A mathematical nonlinear regression model of several parameters (baseline insulin intake, posttransplant 2-h postprandial blood glucose, and stimulated C-peptide) from type 1 diabetics with HbA1c <6.5% who do not require insulin therapy and have no hypoglycemic instances was developed for accurately predicting supplemental insulin requirements in the posttransplant period. An insulin deficit threshold of 0.018 U/kg/day was defined as the average first-year calculated insulin deficit (CID), above which HbA1c rose to >6.5% during year 2 of the posttransplant period. When insulin-untreated subjects were divided into two groups based on whether the average CID was smaller (group I) or greater (group II) than the insulin deficit threshold, HbA1c was found to be similar in the two groups in year 1, but increased significantly in group II to above 6.5% (with mean glucose of 121.9 mg/dl) but remained below 6.5% in group I subjects (with mean glucose of 108.7 mg/dl) in year 2 of the follow-up period. The greater insulin deficit in group II was also associated with a higher susceptibility to hyperglycemia during periods of low serum Rapamune and Prograf levels (combined levels below 11.2 and 4.7 ng/ml, respectively). Although the differences between predicted insulin requirement (PIR) and actual empirical insulin intake in the insulin-treated subjects were generally small, they were nonetheless sufficient to identify over- and underinsulinization at each follow-up visit for all subjects (n = 14 subjects, 135 observations). The newly developed model can effectively identify underinsulinized islet transplant recipients at risk for graft dysfunction due to inadequate supplemental insulin intake or those potentially susceptible to graft function loss due to inadequate immunosuppression. While less common following islet cell therapy, the model can also identify overinsulinized subjects who may be at risk for hypoglycemia.
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Affiliation(s)
- Chris Orr
- Southern California Islet Cell Resources Center, Department of Diabetes, Endocrinology, and Metabolism, Beckman Research Institute of the City of Hope, Duarte, CA, USA
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54
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Bensellam M, Montgomery MK, Luzuriaga J, Chan JY, Laybutt DR. Inhibitor of differentiation proteins protect against oxidative stress by regulating the antioxidant-mitochondrial response in mouse beta cells. Diabetologia 2015; 58:758-70. [PMID: 25636209 DOI: 10.1007/s00125-015-3503-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 12/23/2014] [Indexed: 12/21/2022]
Abstract
AIMS/HYPOTHESIS Oxidative stress is implicated in beta cell glucotoxicity in type 2 diabetes. Inhibitor of differentiation (ID) proteins are transcriptional regulators induced by hyperglycaemia in islets, but the mechanisms involved and their role in beta cells are not clear. Here we investigated whether or not oxidative stress regulates ID levels in beta cells and the role of ID proteins in beta cells during oxidative stress. METHODS MIN6 cells were cultured in H2O2 or ribose to induce oxidative stress. ID1, ID3 and small MAF proteins (MAFF, MAFG and MAFK) were inhibited using small interfering RNA. Isolated islets from Id1(-/-), Id3(-/-) and diabetic db/db mice were used. RESULTS ID1-4 expression was upregulated in vivo in the islets of diabetic db/db mice and stimulated in vitro by ribose and H2O2. Id1/3 inhibition reduced the expression of multiple antioxidant genes and potentiated oxidative stress-induced apoptosis. This finding was associated with increased levels of intracellular reactive oxygen species, altered mitochondrial morphology and reduced expression of Tfam, which encodes a mitochondrial transcription factor, and respiratory chain components. Id1/3 inhibition also reduced the expression of small MAF transcription factors (MafF, MafG and MafK), interacting partners of nuclear factor, erythroid 2-like 2 (NFE2L2), master regulator of the antioxidant response. Inhibition of small MAFs reduced the expression of antioxidant genes and potentiated oxidative stress-induced apoptosis, thus recapitulating the effects of Id1/3 inhibition. CONCLUSIONS/INTERPRETATION Our study identifies IDs as a novel family of oxidative stress-responsive proteins in beta cells. IDs are crucial regulators of the adaptive antioxidant-mitochondrial response that promotes beta cell survival during oxidative stress through a novel link to the NFE2L2-small MAF pathway.
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Affiliation(s)
- Mohammed Bensellam
- Garvan Institute of Medical Research, St Vincent's Hospital, 384 Victoria Street, Darlinghurst, Sydney, NSW, 2010, Australia
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55
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Jacovetti C, Jimenez V, Ayuso E, Laybutt R, Peyot ML, Prentki M, Bosch F, Regazzi R. Contribution of Intronic miR-338-3p and Its Hosting Gene AATK to Compensatory β-Cell Mass Expansion. Mol Endocrinol 2015; 29:693-702. [PMID: 25751313 DOI: 10.1210/me.2014-1299] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The elucidation of the mechanisms directing β-cell mass regeneration and maintenance is of interest, because the deficit of β-cell mass contributes to diabetes onset and progression. We previously found that the level of the microRNA (miRNA) miR-338-3p is decreased in pancreatic islets from rodent models displaying insulin resistance and compensatory β-cell mass expansion, including pregnant rats, diet-induced obese mice, and db/db mice. Transfection of rat islet cells with oligonucleotides that specifically block miR-338-3p activity increased the fraction of proliferating β-cells in vitro and promoted survival under proapoptotic conditions without affecting the capacity of β-cells to release insulin in response to glucose. Here, we evaluated the role of miR-338-3p in vivo by injecting mice with an adeno-associated viral vector permitting specific sequestration of this miRNA in β-cells. We found that the adeno-associated viral construct increased the fraction of proliferating β-cells confirming the data obtained in vitro. miR-338-3p is generated from an intron of the gene coding for apoptosis-associated tyrosine kinase (AATK). Similarly to miR-338-3p, we found that AATK is down-regulated in rat and human islets and INS832/13 β-cells in the presence of the cAMP-raising agents exendin-4, estradiol, and a G-protein-coupled Receptor 30 agonist. Moreover, AATK expression is reduced in islets of insulin resistant animal models and selective silencing of AATK in INS832/13 cells by RNA interference promoted β-cell proliferation. The results point to a coordinated reduction of miR-338-3p and AATK under insulin resistance conditions and provide evidence for a cooperative action of the miRNA and its hosting gene in compensatory β-cell mass expansion.
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Affiliation(s)
- Cécile Jacovetti
- Department of Fundamental Neurosciences (C.J., R.R.), University of Lausanne, 1005 Lausanne, Switzerland; Center of Animal Biotechnology and Gene Therapy and Department of Biochemistry and Molecular Biology (V.J., E.A., F.B.), School of Veterinary Medicine, Universitat Autònoma de Barcelona, 08193 Bellaterra, Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas, Barcelona, Spain; Diabetes and Obesity Research Program (R.L.), Garvan Institute of Medical Research, St. Vincent's Hospital, Sydney, 2010 New South Wales, Australia; and Montreal Diabetes Research Center and Centre de Recherche du Centre Hospitalier de l'Université de Montréal (M.-L.P., M.P.), and Departments of Nutrition, Biochemistry and Molecular Medicine, University of Montreal, Quebec, H2X 0A9 Canada
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Matsuoka TA, Kaneto H, Kawashima S, Miyatsuka T, Tochino Y, Yoshikawa A, Imagawa A, Miyazaki JI, Gannon M, Stein R, Shimomura I. Preserving Mafa expression in diabetic islet β-cells improves glycemic control in vivo. J Biol Chem 2015; 290:7647-57. [PMID: 25645923 DOI: 10.1074/jbc.m114.595579] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The murine Mafa transcription factor is a key regulator of postnatal islet β-cell activity, affecting insulin transcription, insulin secretion, and β-cell mass. Human MAFA expression is also markedly decreased in islet β-cells of type 2 diabetes mellitus (T2DM) patients. Moreover, levels are profoundly reduced in db/db islet β-cells, a mouse model of T2DM. To examine the significance of this key islet β-cell-enriched protein to glycemic control under diabetic conditions, we generated transgenic mice that conditionally and specifically produced Mafa in db/db islet β-cells. Sustained expression of Mafa resulted in significantly lower plasma glucose levels, higher plasma insulin, and augmented islet β-cell mass. In addition, there was increased expression of insulin, Slc2a2, and newly identified Mafa-regulated genes involved in reducing β-cell stress, like Gsta1 and Gckr. Importantly, the levels of human GSTA1 were also compromised in T2DM islets. Collectively, these results illustrate how consequential the reduction in Mafa activity is to islet β-cell function under pathophysiological conditions.
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Affiliation(s)
| | | | | | | | | | | | | | - Jun-ichi Miyazaki
- the Division of Stem Cell Regulation Research, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Maureen Gannon
- the Department of Medicine, Division of Diabetes, Endocrinology, and Metabolism, Vanderbilt University Medical Center, Nashville, Tennessee 37232-6303, and
| | - Roland Stein
- the Department of Molecular Physiology & Biophysics, Vanderbilt University Medical School, Nashville, Tennessee 37232
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57
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Biden TJ, Boslem E, Chu KY, Sue N. Lipotoxic endoplasmic reticulum stress, β cell failure, and type 2 diabetes mellitus. Trends Endocrinol Metab 2014; 25:389-98. [PMID: 24656915 DOI: 10.1016/j.tem.2014.02.003] [Citation(s) in RCA: 155] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2013] [Revised: 02/12/2014] [Accepted: 02/19/2014] [Indexed: 02/06/2023]
Abstract
Failure of the unfolded protein response (UPR) to maintain optimal folding of pro-insulin in the endoplasmic reticulum (ER) leads to unresolved ER stress and β cell death. This contributes not only to some rare forms of diabetes, but also to type 2 diabetes mellitus (T2DM). Many key findings, elaborated over the past decade, are based on the lipotoxicity model, entailing chronic exposure of β cells to elevated levels of fatty acids (FAs). Here, we update recent progress on how FAs initiate ER stress, particularly via disruption of protein trafficking, and how this leads to apoptosis. We also highlight differences in how β cells are impacted by the classic UPR, versus the more selective UPR that arises as part of a broader response to lipotoxicity.
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Affiliation(s)
- Trevor J Biden
- Diabetes and Obesity Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia.
| | - Ebru Boslem
- Diabetes and Obesity Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
| | - Kwan Yi Chu
- Diabetes and Obesity Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
| | - Nancy Sue
- Diabetes and Obesity Program, Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
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58
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Adverse association between obesity and menopause in mice treated with bezafibrate, a pan peroxisome proliferator-activated receptor agonist. Menopause 2014; 20:1264-74. [PMID: 23632658 DOI: 10.1097/gme.0b013e31828f5e3c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVE The goal of this study was to investigate the combined effects of ovariectomy (OVX) and high-fat diet (HF) on insulin sensitivity and pancreatic remodeling in C57BL/6 mice treated with bezafibrate. METHODS Female C57BL/6 mice were subjected to OVX or surgical procedure without removal of the ovary (SHAM). Animals received standard chow (SC; 10% lipids) or HF (60% lipids). After 13 weeks on the diets, the animals were subdivided into six groups based on diet, bezafibrate treatment, or both: SHAM-SC, SHAM-HF, SHAM-HFBz, OVX-SC, OVX-HF, and OVX-HFBz. After treatment for 5 weeks, the pancreas was removed and analyzed using morphometry, stereological tools, immunostaining, and multiplex assay kits. RESULTS SHAM-HF and OVX-HF mice showed increased fasting glucose levels, plasma insulin levels, homeostasis model of assessment for insulin resistance index, body mass, islet hypertrophy, β-cell mass, and insulin immunostaining, but decreased GLUT2 immunostaining. Bezafibrate treatment prevented islet hypertrophy and reduced body mass, plasma insulin levels, and homeostasis model of assessment for insulin resistance index. CONCLUSIONS OVX combined with HF accentuates the effects of menopause, leading to the development of insulin resistance. Bezafibrate treatment reduces body mass, plasma insulin levels, and pancreatic islet hypertrophy in mice fed HF.
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59
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Pullen TJ, Rutter GA. Roles of lncRNAs in pancreatic beta cell identity and diabetes susceptibility. Front Genet 2014; 5:193. [PMID: 25071823 PMCID: PMC4076741 DOI: 10.3389/fgene.2014.00193] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 06/12/2014] [Indexed: 01/09/2023] Open
Abstract
Type 2 diabetes usually ensues from the inability of pancreatic beta cells to compensate for incipient insulin resistance. The loss of beta cell mass, function, and potentially beta cell identity contribute to this dysfunction to extents which are debated. In recent years, long non-coding RNAs (lncRNAs) have emerged as potentially providing a novel level of gene regulation implicating critical cellular processes such as pluripotency and differentiation. With over 1000 lncRNAs now identified in beta cells, there is growing evidence for their involvement in the above processes in these cells. While functional evidence on individual islet lncRNAs is still scarce, we discuss how lncRNAs could contribute to type 2 diabetes susceptibility, particularly at loci identified through genome-wide association studies as affecting disease risk.
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Affiliation(s)
- Timothy J Pullen
- Section of Cell Biology, Department of Medicine, Imperial Centre for Translational and Experimental Medicine, Imperial College London London, UK
| | - Guy A Rutter
- Section of Cell Biology, Department of Medicine, Imperial Centre for Translational and Experimental Medicine, Imperial College London London, UK
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Do OH, Low JT, Gaisano HY, Thorn P. The secretory deficit in islets from db/db mice is mainly due to a loss of responding beta cells. Diabetologia 2014; 57:1400-9. [PMID: 24705605 PMCID: PMC4052007 DOI: 10.1007/s00125-014-3226-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Accepted: 03/07/2014] [Indexed: 12/03/2022]
Abstract
AIMS/HYPOTHESIS We used the db/db mouse to determine the nature of the secretory defect in intact islets. METHODS Glucose tolerance was compared in db/db and wild-type (WT) mice. Isolated islets were used: to measure insulin secretion and calcium in a two-photon assay of single-insulin-granule fusion; and for immunofluorescence of soluble N-ethylmaleimide-sensitive factor attachment proteins (SNAREs). RESULTS The 13-18-week-old db/db mice showed a diabetic phenotype. Isolated db/db islets showed a 77% reduction in insulin secretion induced by 15 mmol/l glucose and reductions in the amplitude and rise-time of the calcium response to glucose. Ionomycin-induced insulin secretion in WT but not db/db islets. Immunofluorescence showed an increase in the levels of the SNAREs synaptosomal-associated protein 25 (SNAP25) and vesicle-associated membrane protein 2 (VAMP2) in db/db islets, but reduced syntaxin-1A. Therefore, db/db islets have both a compromised calcium response to glucose and a compromised secretory response to calcium. Two-photon microscopy of isolated islets determined the number and distribution of insulin granule exocytic events. Compared with WT, db/db islets showed far fewer exocytic events (an 83% decline at 15 mmol/l glucose). This decline was due to a 73% loss of responding cells and, in the remaining responsive cells, a 50% loss of exocytic responses per cell. An assay measuring granule re-acidification showed evidence for more recaptured granules in db/db islets compared with WT. CONCLUSIONS/INTERPRETATION We showed that db/db islets had a reduced calcium response to glucose and a reduction in syntaxin-1A. Within the db/db islets, changes were manifest as both a reduction in responding cells and a reduction in fusing insulin granules per cell.
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Affiliation(s)
- Oanh H. Do
- School of Biomedical Sciences, University of Queensland, St Lucia, QLD 4072 Australia
| | - Jiun T. Low
- School of Biomedical Sciences, University of Queensland, St Lucia, QLD 4072 Australia
| | | | - Peter Thorn
- School of Biomedical Sciences, University of Queensland, St Lucia, QLD 4072 Australia
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Abstract
Over 200 million people worldwide suffer from diabetes, a disorder of glucose homeostasis. The majority of these individuals are diagnosed with type 2 diabetes. It has traditionally been thought that tissue resistance to the action of insulin is the primary defect in type 2 diabetes. However, recent longitudinal and genome‐wide association studies have shown that insulin resistance is more likely to be a precondition, and that the failure of the pancreatic β cell to meet the increased insulin requirements is the triggering factor in the development of type 2 diabetes. A major emphasis in diabetes research has therefore shifted to understanding the causes of β cell failure. Collectively, these studies have implicated a complex network of triggers, which activate intersecting execution pathways leading to β cell dysfunction and death. In the present review, we discuss these triggers (glucotoxicity, lipotoxicity, amyloid and cytokines) with respect to the pathways they activate (oxidative stress, inflammation and endoplasmic reticulum stress) and propose a model for understanding β cell failure in type 2 diabetes. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2010.00021.x, 2010)
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Affiliation(s)
- Takeshi Ogihara
- Department of Pediatrics and the Herman B Wells Center for Pediatric Research
| | - Raghavendra G Mirmira
- Department of Pediatrics and the Herman B Wells Center for Pediatric Research ; Departments of Medicine and Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, IN, USA
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Kaspi H, Pasvolsky R, Hornstein E. Could microRNAs contribute to the maintenance of β cell identity? Trends Endocrinol Metab 2014; 25:285-92. [PMID: 24656914 DOI: 10.1016/j.tem.2014.01.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Revised: 01/21/2014] [Accepted: 01/29/2014] [Indexed: 12/22/2022]
Abstract
Normal physiology depends on defined functional output of differentiated cells. However, differentiated cells are often surprisingly fragile. As an example, phenotypic collapse and dedifferentiation of β cells were recently discovered in the pathogenesis of type 2 diabetes (T2D). These discoveries necessitate the investigation of mechanisms that function to maintain robust cell type identity. microRNAs (miRNAs), which are small non-coding RNAs, are known to impart robustness to development. miRNAs are interlaced within networks, that include also transcriptional and epigenetic regulators, for continuous control of lineage-specific gene expression. In this Opinion article, we provide a framework for conceptualizing how miRNAs might participate in adult β cell identity and suggest that miRNAs may function as important genetic components in metabolic disorders, including diabetes.
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Affiliation(s)
- Haggai Kaspi
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Ronit Pasvolsky
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Eran Hornstein
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.
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Yan PK, Zhang LN, Feng Y, Qu H, Qin L, Zhang LS, Leng Y. SHR3824, a novel selective inhibitor of renal sodium glucose cotransporter 2, exhibits antidiabetic efficacy in rodent models. Acta Pharmacol Sin 2014; 35:613-24. [PMID: 24786232 PMCID: PMC4814034 DOI: 10.1038/aps.2013.196] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Accepted: 12/30/2013] [Indexed: 01/16/2023] Open
Abstract
AIM The sodium glucose cotransporter 2 (SGLT2) plays an important role in renal glucose reabsorption, thus serves as a new target for the treatment of diabetes. The purpose of this study was to evaluate SHR3824 as a novel selective SGLT2 inhibitor and to characterize its in vivo effects on glucose homeostasis. The effects of chronic administration of SHR3824 on peripheral insulin sensitivity and pancreatic β-cell function were also investigated. METHODS The in vitro potency and selectivity of SHR3824 were assessed in HEK293 cells transfected with human SGLT2 or SGLT1. Acute and multi-dose studies were performed on ICR mice, GK rats and db/db mice to assess the ability of SHR3824 to enhance urinary glucose excretion and improve blood glucose levels. 2-Deoxyglucose uptake and insulin immunohistochemical staining were performed in the soleus muscle and pancreas, respectively, of db/db mice. A selective SGLT2 inhibitor BMS512148 (dapagliflozin) was taken as positive control. RESULTS SHR3824 potently inhibited human SGLT2 in vitro, but exerted much weak inhibition on human SGLT1 (the IC50 values of SHR3824 against human SGLT2 and SGLT1 were 2.38 and 4324 nmol/L, respectively). Acute oral administration of SHR3824 (0.3, 1.0, 3.0 mg/kg) dose-dependently improved glucose tolerance in ICR mice, and reduced hyperglycemia by increasing urinary glucose excretion in GK rats and db/db mice. Chronic oral administration of SHR3824 (0.3, 1.0, 3.0 mg·kg(-1)·d(-1)) dose-dependently reduced blood glucose and HbA1c levels in GK rats and db/db mice, and significantly increased insulin-stimulated glucose uptake in the soleus muscles and enhanced insulin staining in the islet cells of db/db mice. CONCLUSION SHR3824 is a potent and selective SGLT2 inhibitor and exhibits antidiabetic efficacy in several rodent models, suggesting its potential as a new therapeutic agent for the treatment of type 2 diabetes.
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Affiliation(s)
- Pang-ke Yan
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Li-na Zhang
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Ying Feng
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Hui Qu
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Li Qin
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Lian-shan Zhang
- Shanghai Hengrui Pharmaceuticals Co, Ltd, Shanghai 200245, China
| | - Ying Leng
- State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
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D'souza AM, Asadi A, Johnson JD, Covey SD, Kieffer TJ. Leptin deficiency in rats results in hyperinsulinemia and impaired glucose homeostasis. Endocrinology 2014; 155:1268-79. [PMID: 24467741 DOI: 10.1210/en.2013-1523] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Leptin, an adipocyte-derived hormone, has well-established anorexigenic effects but is also able to regulate glucose homeostasis independent of body weight. Until recently, the ob/ob mouse was the only animal model of global leptin deficiency. Here we report the effects of leptin deficiency on glucose homeostasis in male and female leptin knockout (KO) rats. Leptin KO rats developed obesity by 6 to 7 weeks of age, and lipid mass was increased by more than 2-fold compared with that of wild-type (WT) littermates at 18 weeks of age. Hyperinsulinemia and insulin resistance were evident in both males and females and were sustained with aging. Male KO rats experienced transient mild fasting hyperglycemia between 14 and 25 weeks of age, but thereafter fasting glucose levels were comparable to those of WT littermates up to 36 weeks of age. Fasting glucose levels of female KO rats were similar to those of WT littermates. Male KO rats exhibited a 3-fold increase in the proportion of β-cell area relative to total pancreas at 36 weeks of age. Islets from 12-week-old KO rats secreted more insulin when stimulated than islets from WT littermates. Leptin replacement via miniosmotic pump (100 μg/d) reduced food intake, attenuated weight gain, normalized glucose tolerance, and improved glucose-stimulated insulin secretion and insulin sensitivity. Together, these data demonstrate that the absence of leptin in rats recapitulates some of the phenotype previously observed in ob/ob mice including development of hyperinsulinemia, obesity, and insulin resistance.
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Affiliation(s)
- Anna M D'souza
- Department of Cellular and Physiological Sciences (A.M.D., A.A., J.D.J., T.J.K.), Department of Biochemistry and Molecular Biology (S.D.C.), and Department of Surgery (J.D.J., T.J.K.), University of British Columbia, Vancouver British Columbia, Canada V5Z 4E3
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65
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Puri S, Akiyama H, Hebrok M. VHL-mediated disruption of Sox9 activity compromises β-cell identity and results in diabetes mellitus. Genes Dev 2014; 27:2563-75. [PMID: 24298056 PMCID: PMC3861670 DOI: 10.1101/gad.227785.113] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
β-Cell dysfunction contributes to diabetes mellitus. Puri et al. show that deletion of the von Hippel-Lindau (Vhlh) gene is deleterious to canonical β-cell gene expression. Vhlh loss triggers erroneous expression of factors normally active in progenitor cells, including Sox9. β-Cell-specific expression of Sox9 results in diabetes mellitus. This study reveals that perturbed β-cell identity contributes to diabetes mellitus. Precise functioning of the pancreatic β cell is paramount to whole-body glucose homeostasis, and β-cell dysfunction contributes significantly to diabetes mellitus. Using transgenic mouse models, we demonstrate that deletion of the von Hippel-Lindau (Vhlh) gene (encoding an E3 ubiquitin ligase implicated in, among other functions, oxygen sensing in pancreatic β cells) is deleterious to canonical β-cell gene expression. This triggers erroneous expression of factors normally active in progenitor cells, including effectors of the Notch, Wnt, and Hedgehog signaling cascades. Significantly, an up-regulation of the transcription factor Sox9, normally excluded from functional β cells, occurs upon deletion of Vhlh. Sox9 plays important roles during pancreas development but does not have a described role in the adult β cell. β-Cell-specific ectopic expression of Sox9 results in diabetes mellitus from similar perturbations in β-cell identity. These findings reveal that assaults on the β cell that impact the differentiation state of the cell have clear implications toward our understanding of diabetes mellitus.
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Affiliation(s)
- Sapna Puri
- Diabetes Center, Department of Medicine, University of California at San Francisco, San Francisco, California 94143, USA
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66
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Lee-Kubli CA, Mixcoatl-Zecuatl T, Jolivalt CG, Calcutt NA. Animal models of diabetes-induced neuropathic pain. Curr Top Behav Neurosci 2014; 20:147-70. [PMID: 24510303 DOI: 10.1007/7854_2014_280] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Neuropathy will afflict over half of the approximately 350 million people worldwide who currently suffer from diabetes and around one-third of diabetic patients with neuropathy will suffer from painful symptoms that may be spontaneous or stimulus evoked. Diabetes can be induced in rats or mice by genetic, dietary, or chemical means, and there are a variety of well-characterized models of diabetic neuropathy that replicate either type 1 or type 2 diabetes. Diabetic rodents display aspects of sensorimotor dysfunction such as stimulus-evoked allodynia and hyperalgesia that are widely used to model painful neuropathy. This allows investigation of pathogenic mechanisms and development of potential therapeutic interventions that may alleviate established pain or prevent onset of pain.
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67
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Plaisance V, Waeber G, Regazzi R, Abderrahmani A. Role of microRNAs in islet beta-cell compensation and failure during diabetes. J Diabetes Res 2014; 2014:618652. [PMID: 24734255 PMCID: PMC3964735 DOI: 10.1155/2014/618652] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Accepted: 01/24/2014] [Indexed: 12/12/2022] Open
Abstract
Pancreatic beta-cell function and mass are markedly adaptive to compensate for the changes in insulin requirement observed during several situations such as pregnancy, obesity, glucocorticoids excess, or administration. This requires a beta-cell compensation which is achieved through a gain of beta-cell mass and function. Elucidating the physiological mechanisms that promote functional beta-cell mass expansion and that protect cells against death, is a key therapeutic target for diabetes. In this respect, several recent studies have emphasized the instrumental role of microRNAs in the control of beta-cell function. MicroRNAs are negative regulators of gene expression, and are pivotal for the control of beta-cell proliferation, function, and survival. On the one hand, changes in specific microRNA levels have been associated with beta-cell compensation and are triggered by hormones or bioactive peptides that promote beta-cell survival and function. Conversely, modifications in the expression of other specific microRNAs contribute to beta-cell dysfunction and death elicited by diabetogenic factors including, cytokines, chronic hyperlipidemia, hyperglycemia, and oxidized LDL. This review underlines the importance of targeting the microRNA network for future innovative therapies aiming at preventing the beta-cell decline in diabetes.
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Affiliation(s)
- Valérie Plaisance
- Lille 2 University, European Genomic Institute for Diabetes (EGID), FR 3508, UMR-8199 Lille, France
| | - Gérard Waeber
- Service of Internal Medicine, Hospital-University of Lausanne (CHUV), 1011 Lausanne, Switzerland
| | - Romano Regazzi
- Department of Fundamental Neurosciences, University of Lausanne, 1005 Lausanne, Switzerland
| | - Amar Abderrahmani
- Lille 2 University, European Genomic Institute for Diabetes (EGID), FR 3508, UMR-8199 Lille, France
- *Amar Abderrahmani:
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68
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Dalbøge LS, Almholt DLC, Neerup TSR, Vassiliadis E, Vrang N, Pedersen L, Fosgerau K, Jelsing J. Characterisation of age-dependent beta cell dynamics in the male db/db mice. PLoS One 2013; 8:e82813. [PMID: 24324833 PMCID: PMC3855780 DOI: 10.1371/journal.pone.0082813] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Accepted: 11/06/2013] [Indexed: 12/20/2022] Open
Abstract
Aim To characterise changes in pancreatic beta cell mass during the development of diabetes in untreated male C57BLKS/J db/db mice. Methods Blood samples were collected from a total of 72 untreated male db/db mice aged 5, 6, 8, 10, 12, 14, 18, 24 and 34 weeks, for measurement of terminal blood glucose, HbA1c, plasma insulin, and C-peptide. Pancreata were removed for quantification of beta cell mass, islet numbers as well as proliferation and apoptosis by immunohistochemistry and stereology. Results Total pancreatic beta cell mass increased significantly from 2.1 ± 0.3 mg in mice aged 5 weeks to a peak value of 4.84 ± 0.26 mg (P < 0.05) in 12-week-old mice, then gradually decreased to 3.27 ± 0.44 mg in mice aged 34 weeks. Analysis of islets in the 5-, 10-, and 24-week age groups showed increased beta cell proliferation in the 10-week-old animals whereas a low proliferation is seen in older animals. The expansion in beta cell mass was driven by an increase in mean islet mass as the total number of islets was unchanged in the three groups. Conclusions/Interpretation The age-dependent beta cell dynamics in male db/db mice has been described from 5-34 weeks of age and at the same time alterations in insulin/glucose homeostasis were assessed. High beta cell proliferation and increased beta cell mass occur in young animals followed by a gradual decline characterised by a low beta cell proliferation in older animals. The expansion of beta cell mass was caused by an increase in mean islet mass and not islet number.
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Affiliation(s)
| | | | - Trine S. R. Neerup
- Department of Research and Development, Zealand Pharma A/S, Glostrup, Denmark
| | | | - Niels Vrang
- Department of Histology, Gubra ApS, Hørsholm, Denmark
| | - Lars Pedersen
- Department of Stereology, Visiopharm, Hørsholm, Denmark
| | - Keld Fosgerau
- Department of Research and Development, Zealand Pharma A/S, Glostrup, Denmark
| | - Jacob Jelsing
- Department of Histology, Gubra ApS, Hørsholm, Denmark
- * E-mail:
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69
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Walters SN, Luzuriaga J, Chan JY, Grey ST, Laybutt DR. Influence of chronic hyperglycemia on the loss of the unfolded protein response in transplanted islets. J Mol Endocrinol 2013; 51:225-32. [PMID: 23833251 DOI: 10.1530/jme-13-0016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Chronic hyperglycemia contributes to β-cell dysfunction in diabetes and with islet transplantation, but the mechanisms remain unclear. Recent studies demonstrate that the unfolded protein response (UPR) is critical for β-cell function. Here, we assessed the influence of hyperglycemia on UPR gene expression in transplanted islets. Streptozotocin-induced diabetic or control nondiabetic mice were transplanted under the kidney capsule with syngeneic islets either sufficient or not to normalize hyperglycemia. Twenty-one days after transplantation, islet grafts were excised and RT-PCR was used to assess gene expression. In islet grafts from diabetic mice, expression levels of many UPR genes of the IRE1/ATF6 pathways, which are important for adaptation to endoplasmic reticulum stress, were markedly reduced compared with that in islet grafts from control mice. UPR genes of the PERK pathway were also downregulated. The normalization of glycemia restored the changes in mRNA expression, suggesting that chronic hyperglycemia contributes to the downregulation of multiple arms of UPR gene expression. Similar correlations were observed between blood glucose and mRNA levels of transcription factors involved in the maintenance of β-cell phenotype and genes implicated in β-cell function, suggesting convergent regulation of UPR gene expression and β-cell differentiation by hyperglycemia. However, the normalization of glycemia was not accompanied by restoration of antioxidant or pro-inflammatory cytokine mRNA levels, which were increased in islet grafts from diabetic mice. These studies demonstrate that chronic hyperglycemia contributes to the downregulation of multiple arms of UPR gene expression in transplanted mouse islets. Failure of the adaptive UPR may contribute to β-cell dedifferentiation and dysfunction in diabetes.
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Affiliation(s)
- Stacey N Walters
- Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, Sydney, New South Wales 2010, Australia St Vincent's Clinical School, University of New South Wales, Sydney, New South Wales, Australia
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70
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Gosmain Y, Masson MH, Philippe J. Glucagon: the renewal of an old hormone in the pathophysiology of diabetes. J Diabetes 2013; 5:102-9. [PMID: 23302052 DOI: 10.1111/1753-0407.12022] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Accepted: 12/14/2012] [Indexed: 12/24/2022] Open
Abstract
Type 2 diabetes (T2D) is one of the most common diseases, affecting 5-10% of the population in most countries; the progression of its prevalence has been constant over the past 50 years in all countries worldwide, creating a major public health problem in terms of disease management and financial burden. Although the pathophysiology of T2D has been attributed for decades to insulin resistance and decreased insulin secretion, particularly in response to glucose, the contributing role of glucagon in hyperglycemia has been highlighted since the early 1970s by demonstrating its glycogenolytic, gluconeogenic and ketogenic properties. More recently, the importance of glucagon in diabetes has been highlighted in a model of streptozotocin-induced diabetic mice becoming euglycemic in the absence of glucagon receptors and without insulin treatment. Understanding the dysregulation of α-cells in diabetes will be critical to better define the pathophysiology of diabetes and develop new antidiabetic treatment.
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Affiliation(s)
- Yvan Gosmain
- Service of Endocrinology, Diabetes, Hypertension and Nutrition, University Hospital Geneva, Geneva, Switzerland
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71
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Cantley J, Biden TJ. Sweet and sour β-cells: ROS and Hif1α induce Warburg-like lactate production during type 2 diabetes. Diabetes 2013; 62:1823-5. [PMID: 23704526 PMCID: PMC3661644 DOI: 10.2337/db13-0272] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- James Cantley
- Diabetes and Obesity Research Program, Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia.
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72
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Chan JY, Luzuriaga J, Bensellam M, Biden TJ, Laybutt DR. Failure of the adaptive unfolded protein response in islets of obese mice is linked with abnormalities in β-cell gene expression and progression to diabetes. Diabetes 2013; 62:1557-68. [PMID: 23274897 PMCID: PMC3636637 DOI: 10.2337/db12-0701] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The normal β-cell response to obesity-associated insulin resistance is hypersecretion of insulin. Type 2 diabetes develops in subjects with β-cells that are susceptible to failure. Here, we investigated the time-dependent gene expression changes in islets of diabetes-prone db/db and diabetes-resistant ob/ob mice. The expressions of adaptive unfolded protein response (UPR) genes were progressively induced in islets of ob/ob mice, whereas they declined in diabetic db/db mice. Genes important for β-cell function and maintenance of the islet phenotype were reduced with time in db/db mice, whereas they were preserved in ob/ob mice. Inflammation and antioxidant genes displayed time-dependent upregulation in db/db islets but were unchanged in ob/ob islets. Treatment of db/db mouse islets with the chemical chaperone 4-phenylbutyric acid partially restored the changes in several β-cell function genes and transcription factors but did not affect inflammation or antioxidant gene expression. These data suggest that the maintenance (or suppression) of the adaptive UPR is associated with β-cell compensation (or failure) in obese mice. Inflammation, oxidative stress, and a progressive loss of β-cell differentiation accompany diabetes progression. The ability to maintain the adaptive UPR in islets may protect against the gene expression changes that underlie diabetes development in obese mice.
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73
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Kang ZF, Deng Y, Zhou Y, Fan RR, Chan JCN, Laybutt DR, Luzuriaga J, Xu G. Pharmacological reduction of NEFA restores the efficacy of incretin-based therapies through GLP-1 receptor signalling in the beta cell in mouse models of diabetes. Diabetologia 2013; 56. [PMID: 23188390 PMCID: PMC3536946 DOI: 10.1007/s00125-012-2776-x] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
AIMS/HYPOTHESIS Type 2 diabetes mellitus is associated with reduced incretin effects. Although previous studies have shown that hyperglycaemia contributes to impaired incretin responses in beta cells, it is largely unknown how hyperlipidaemia, another feature of type 2 diabetes, contributes to impaired glucagon-like peptide 1 (GLP-1) response. Here, we investigated the effects of NEFA on incretin receptor signalling and examined the glucose-lowering efficacy of incretin-based drugs in combination with the lipid-lowering agent bezafibrate. METHODS We used db/db mice to examine the in vivo efficacy of the treatment. Beta cell lines and mouse islets were used to examine GLP-1 and glucose-dependent insulinotropic peptide receptor signalling. RESULTS Palmitate treatment decreased Glp1r expression in rodent insulinoma cell lines and isolated islets. This was associated with impairment of the following: GLP-1-stimulated cAMP production, phosphorylation of cAMP-responsive elements binding protein (CREB) and insulin secretion. In insulinoma cell lines, the expression of exogenous Glp1r restored cAMP production and the phosphorylation of CREB. Treatment with bezafibrate in combination with des-fluoro-sitagliptin or exendin-4 led to more robust glycaemic control, associated with improved islet morphology and beta cell mass in db/db mice. CONCLUSIONS/INTERPRETATION Elevated NEFA contributes to impaired responsiveness to GLP-1, partially through downregulation of GLP-1 receptor signalling. Improvements in lipid control in mouse models of obesity and diabetes increase the efficacy of incretin-based therapy.
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Affiliation(s)
- Z. F. Kang
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Rm 114038, 9/F, Clinical Science Building, Prince of Wales Hospital Shatin, Hong Kong, SAR People’s Republic of China
- Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong, SAR People’s Republic of China
| | - Y. Deng
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Rm 114038, 9/F, Clinical Science Building, Prince of Wales Hospital Shatin, Hong Kong, SAR People’s Republic of China
| | - Y. Zhou
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Rm 114038, 9/F, Clinical Science Building, Prince of Wales Hospital Shatin, Hong Kong, SAR People’s Republic of China
| | - R. R. Fan
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Rm 114038, 9/F, Clinical Science Building, Prince of Wales Hospital Shatin, Hong Kong, SAR People’s Republic of China
| | - J. C. N. Chan
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Rm 114038, 9/F, Clinical Science Building, Prince of Wales Hospital Shatin, Hong Kong, SAR People’s Republic of China
- Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong, SAR People’s Republic of China
- Hong Kong Institute of Diabetes and Obesity, The Chinese University of Hong Kong, Hong Kong, SAR People’s Republic of China
| | - D. R. Laybutt
- Diabetes and Obesity Research Program, Garvan Institute of Medical Research, Sydney, NSW Australia
| | - J. Luzuriaga
- Diabetes and Obesity Research Program, Garvan Institute of Medical Research, Sydney, NSW Australia
| | - G. Xu
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Rm 114038, 9/F, Clinical Science Building, Prince of Wales Hospital Shatin, Hong Kong, SAR People’s Republic of China
- Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Hong Kong, SAR People’s Republic of China
- Hong Kong Institute of Diabetes and Obesity, The Chinese University of Hong Kong, Hong Kong, SAR People’s Republic of China
- Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, People’s Republic of China
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74
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Weir GC, Bonner-Weir S. Islet β cell mass in diabetes and how it relates to function, birth, and death. Ann N Y Acad Sci 2013; 1281:92-105. [PMID: 23363033 PMCID: PMC3618572 DOI: 10.1111/nyas.12031] [Citation(s) in RCA: 236] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In type 1 diabetes (T1D) β cell mass is markedly reduced by autoimmunity. Type 2 diabetes (T2D) results from inadequate β cell mass and function that can no longer compensate for insulin resistance. The reduction of β cell mass in T2D may result from increased cell death and/or inadequate birth through replication and neogenesis. Reduction in mass allows glucose levels to rise, which places β cells in an unfamiliar hyperglycemic environment, leading to marked changes in their phenotype and a dramatic loss of glucose-stimulated insulin secretion (GSIS), which worsens as glucose levels climb. Toxic effects of glucose on β cells (glucotoxicity) appear to be the culprit. This dysfunctional insulin secretion can be reversed when glucose levels are lowered by treatment, a finding with therapeutic significance. Restoration of β cell mass in both types of diabetes could be accomplished by either β cell regeneration or transplantation. Learning more about the relationships between β cell mass, turnover, and function and finding ways to restore β cell mass are among the most urgent priorities for diabetes research.
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Affiliation(s)
- Gordon C Weir
- Section on Islet Cell Biology and Regenerative Medicine, Research Division, Joslin Diabetes Center, Department of Medicine, Harvard Medical School, Boston, MA 02215, USA.
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75
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Bensellam M, Laybutt DR, Jonas JC. The molecular mechanisms of pancreatic β-cell glucotoxicity: recent findings and future research directions. Mol Cell Endocrinol 2012; 364:1-27. [PMID: 22885162 DOI: 10.1016/j.mce.2012.08.003] [Citation(s) in RCA: 208] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 07/11/2012] [Accepted: 08/01/2012] [Indexed: 02/06/2023]
Abstract
It is well established that regular physiological stimulation by glucose plays a crucial role in the maintenance of the β-cell differentiated phenotype. In contrast, prolonged or repeated exposure to elevated glucose concentrations both in vitro and in vivo exerts deleterious or toxic effects on the β-cell phenotype, a concept termed as glucotoxicity. Evidence indicates that the latter may greatly contribute to the pathogenesis of type 2 diabetes. Through the activation of several mechanisms and signaling pathways, high glucose levels exert deleterious effects on β-cell function and survival and thereby, lead to the worsening of the disease over time. While the role of high glucose-induced β-cell overstimulation, oxidative stress, excessive Unfolded Protein Response (UPR) activation, and loss of differentiation in the alteration of the β-cell phenotype is well ascertained, at least in vitro and in animal models of type 2 diabetes, the role of other mechanisms such as inflammation, O-GlcNacylation, PKC activation, and amyloidogenesis requires further confirmation. On the other hand, protein glycation is an emerging mechanism that may play an important role in the glucotoxic deterioration of the β-cell phenotype. Finally, our recent evidence suggests that hypoxia may also be a new mechanism of β-cell glucotoxicity. Deciphering these molecular mechanisms of β-cell glucotoxicity is a mandatory first step toward the development of therapeutic strategies to protect β-cells and improve the functional β-cell mass in type 2 diabetes.
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Affiliation(s)
- Mohammed Bensellam
- Université catholique de Louvain, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Brussels, Belgium
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76
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Abstract
Hyperglycaemia has multiple effects on β-cells, some clearly prosecretory, including hyperplasia and elevated insulin content, but eventually, a 'glucotoxic' effect which leads to pancreatic β-cell dysfunction, reduced β-cell mass and insulin deficiency, is an important part of diabetes pathophysiology. Myriad underlying cellular and molecular processes could lead to such dysfunction. High glucose will stimulate glycolysis and oxidative phosphorylation, which will in turn increase β-cell membrane excitability through K(ATP) channel closure. Chronic hyperexcitability will then lead to persistently elevated [Ca(2+)](i), a key trigger to insulin secretion. Thus, at least a part of the consequence of 'hyperstimulation' by glucose has been suggested to be a result of 'hyperexcitability' and chronically elevated [Ca(2+)](i). This link is lost when the [glucose], K(ATP) -channel activity link is broken, either pharmacologically or genetically. In isolated islets, such studies reveal that hyperexcitability causes a largely reversible chronic loss of insulin content, but in vivo chronic hyperexcitability per se does not lead to β-cell death or loss of insulin content. On the other hand, chronic inexcitability in vivo leads to systemic diabetes and consequential β-cell death, even while [Ca(2+)](i) remains low.
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Affiliation(s)
- C G Nichols
- Department of Cell Biology and Physiology and Center for Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, MO 63110, USA.
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77
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Jacovetti C, Abderrahmani A, Parnaud G, Jonas JC, Peyot ML, Cornu M, Laybutt R, Meugnier E, Rome S, Thorens B, Prentki M, Bosco D, Regazzi R. MicroRNAs contribute to compensatory β cell expansion during pregnancy and obesity. J Clin Invest 2012; 122:3541-51. [PMID: 22996663 PMCID: PMC3461923 DOI: 10.1172/jci64151] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 07/19/2012] [Indexed: 01/09/2023] Open
Abstract
Pregnancy and obesity are frequently associated with diminished insulin sensitivity, which is normally compensated for by an expansion of the functional β cell mass that prevents chronic hyperglycemia and development of diabetes mellitus. The molecular basis underlying compensatory β cell mass expansion is largely unknown. We found in rodents that β cell mass expansion during pregnancy and obesity is associated with changes in the expression of several islet microRNAs, including miR-338-3p. In isolated pancreatic islets, we recapitulated the decreased miR-338-3p level observed in gestation and obesity by activating the G protein-coupled estrogen receptor GPR30 and the glucagon-like peptide 1 (GLP1) receptor. Blockade of miR-338-3p in β cells using specific anti-miR molecules mimicked gene expression changes occurring during β cell mass expansion and resulted in increased proliferation and improved survival both in vitro and in vivo. These findings point to a major role for miR-338-3p in compensatory β cell mass expansion occurring under different insulin resistance states.
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MESH Headings
- Adaptation, Physiological/physiology
- Animals
- Cells, Cultured/drug effects
- Cells, Cultured/metabolism
- Cytokines/biosynthesis
- Cytokines/genetics
- Estradiol/analogs & derivatives
- Estradiol/pharmacology
- Estradiol/physiology
- Estrogen Antagonists/pharmacology
- Female
- Fulvestrant
- Gene Expression Regulation/physiology
- Glucagon-Like Peptide 1/physiology
- Glucagon-Like Peptide-1 Receptor
- Insulin Resistance/physiology
- Islets of Langerhans/growth & development
- Islets of Langerhans/metabolism
- Islets of Langerhans/pathology
- Male
- Mice
- Mice, Mutant Strains
- MicroRNAs/biosynthesis
- MicroRNAs/genetics
- MicroRNAs/physiology
- Obesity/pathology
- Obesity/physiopathology
- Organ Size/drug effects
- Postpartum Period/metabolism
- Pregnancy/metabolism
- Pregnancy/physiology
- Rats
- Rats, Wistar
- Receptors, G-Protein-Coupled/agonists
- Receptors, G-Protein-Coupled/biosynthesis
- Receptors, G-Protein-Coupled/genetics
- Receptors, Glucagon/agonists
- Receptors, Glucagon/deficiency
- Signal Transduction/drug effects
- Signal Transduction/physiology
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Affiliation(s)
- Cécile Jacovetti
- Department of Cell Biology and Morphology, University of Lausanne, Lausanne, Switzerland.
University of Lille Nord de France, European Genomic Institute for Diabetes EGID FR 3508, UMR 8199, Lille, France.
Cell Isolation and Transplantation Center, Department of Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland.
Université catholique de Louvain, Institut de recherche expérimentale et clinique, Pôle d’endocrinologie, diabète et nutrition, Brussels, Belgium.
Montreal Diabetes Research Center and CRCHUM, Montreal, Quebec, Canada.
Departments of Nutrition and Biochemistry, University of Montreal, Montreal, Quebec, Canada.
Center for Integrative Genomics, University of Lausanne, Genopode Building, Lausanne, Switzerland.
Diabetes and Obesity Research Program, Garvan Institute of Medical Research, St. Vincent’s Hospital, Sydney, New South Wales, Australia.
Laboratory CarMen (INSERM 1060, INRA 1235, INSA), University of Lyon, Faculté de Médecine Lyon-Sud, Chemin du Grand Revoyet, Oullins, France
| | - Amar Abderrahmani
- Department of Cell Biology and Morphology, University of Lausanne, Lausanne, Switzerland.
University of Lille Nord de France, European Genomic Institute for Diabetes EGID FR 3508, UMR 8199, Lille, France.
Cell Isolation and Transplantation Center, Department of Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland.
Université catholique de Louvain, Institut de recherche expérimentale et clinique, Pôle d’endocrinologie, diabète et nutrition, Brussels, Belgium.
Montreal Diabetes Research Center and CRCHUM, Montreal, Quebec, Canada.
Departments of Nutrition and Biochemistry, University of Montreal, Montreal, Quebec, Canada.
Center for Integrative Genomics, University of Lausanne, Genopode Building, Lausanne, Switzerland.
Diabetes and Obesity Research Program, Garvan Institute of Medical Research, St. Vincent’s Hospital, Sydney, New South Wales, Australia.
Laboratory CarMen (INSERM 1060, INRA 1235, INSA), University of Lyon, Faculté de Médecine Lyon-Sud, Chemin du Grand Revoyet, Oullins, France
| | - Géraldine Parnaud
- Department of Cell Biology and Morphology, University of Lausanne, Lausanne, Switzerland.
University of Lille Nord de France, European Genomic Institute for Diabetes EGID FR 3508, UMR 8199, Lille, France.
Cell Isolation and Transplantation Center, Department of Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland.
Université catholique de Louvain, Institut de recherche expérimentale et clinique, Pôle d’endocrinologie, diabète et nutrition, Brussels, Belgium.
Montreal Diabetes Research Center and CRCHUM, Montreal, Quebec, Canada.
Departments of Nutrition and Biochemistry, University of Montreal, Montreal, Quebec, Canada.
Center for Integrative Genomics, University of Lausanne, Genopode Building, Lausanne, Switzerland.
Diabetes and Obesity Research Program, Garvan Institute of Medical Research, St. Vincent’s Hospital, Sydney, New South Wales, Australia.
Laboratory CarMen (INSERM 1060, INRA 1235, INSA), University of Lyon, Faculté de Médecine Lyon-Sud, Chemin du Grand Revoyet, Oullins, France
| | - Jean-Christophe Jonas
- Department of Cell Biology and Morphology, University of Lausanne, Lausanne, Switzerland.
University of Lille Nord de France, European Genomic Institute for Diabetes EGID FR 3508, UMR 8199, Lille, France.
Cell Isolation and Transplantation Center, Department of Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland.
Université catholique de Louvain, Institut de recherche expérimentale et clinique, Pôle d’endocrinologie, diabète et nutrition, Brussels, Belgium.
Montreal Diabetes Research Center and CRCHUM, Montreal, Quebec, Canada.
Departments of Nutrition and Biochemistry, University of Montreal, Montreal, Quebec, Canada.
Center for Integrative Genomics, University of Lausanne, Genopode Building, Lausanne, Switzerland.
Diabetes and Obesity Research Program, Garvan Institute of Medical Research, St. Vincent’s Hospital, Sydney, New South Wales, Australia.
Laboratory CarMen (INSERM 1060, INRA 1235, INSA), University of Lyon, Faculté de Médecine Lyon-Sud, Chemin du Grand Revoyet, Oullins, France
| | - Marie-Line Peyot
- Department of Cell Biology and Morphology, University of Lausanne, Lausanne, Switzerland.
University of Lille Nord de France, European Genomic Institute for Diabetes EGID FR 3508, UMR 8199, Lille, France.
Cell Isolation and Transplantation Center, Department of Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland.
Université catholique de Louvain, Institut de recherche expérimentale et clinique, Pôle d’endocrinologie, diabète et nutrition, Brussels, Belgium.
Montreal Diabetes Research Center and CRCHUM, Montreal, Quebec, Canada.
Departments of Nutrition and Biochemistry, University of Montreal, Montreal, Quebec, Canada.
Center for Integrative Genomics, University of Lausanne, Genopode Building, Lausanne, Switzerland.
Diabetes and Obesity Research Program, Garvan Institute of Medical Research, St. Vincent’s Hospital, Sydney, New South Wales, Australia.
Laboratory CarMen (INSERM 1060, INRA 1235, INSA), University of Lyon, Faculté de Médecine Lyon-Sud, Chemin du Grand Revoyet, Oullins, France
| | - Marion Cornu
- Department of Cell Biology and Morphology, University of Lausanne, Lausanne, Switzerland.
University of Lille Nord de France, European Genomic Institute for Diabetes EGID FR 3508, UMR 8199, Lille, France.
Cell Isolation and Transplantation Center, Department of Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland.
Université catholique de Louvain, Institut de recherche expérimentale et clinique, Pôle d’endocrinologie, diabète et nutrition, Brussels, Belgium.
Montreal Diabetes Research Center and CRCHUM, Montreal, Quebec, Canada.
Departments of Nutrition and Biochemistry, University of Montreal, Montreal, Quebec, Canada.
Center for Integrative Genomics, University of Lausanne, Genopode Building, Lausanne, Switzerland.
Diabetes and Obesity Research Program, Garvan Institute of Medical Research, St. Vincent’s Hospital, Sydney, New South Wales, Australia.
Laboratory CarMen (INSERM 1060, INRA 1235, INSA), University of Lyon, Faculté de Médecine Lyon-Sud, Chemin du Grand Revoyet, Oullins, France
| | - Ross Laybutt
- Department of Cell Biology and Morphology, University of Lausanne, Lausanne, Switzerland.
University of Lille Nord de France, European Genomic Institute for Diabetes EGID FR 3508, UMR 8199, Lille, France.
Cell Isolation and Transplantation Center, Department of Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland.
Université catholique de Louvain, Institut de recherche expérimentale et clinique, Pôle d’endocrinologie, diabète et nutrition, Brussels, Belgium.
Montreal Diabetes Research Center and CRCHUM, Montreal, Quebec, Canada.
Departments of Nutrition and Biochemistry, University of Montreal, Montreal, Quebec, Canada.
Center for Integrative Genomics, University of Lausanne, Genopode Building, Lausanne, Switzerland.
Diabetes and Obesity Research Program, Garvan Institute of Medical Research, St. Vincent’s Hospital, Sydney, New South Wales, Australia.
Laboratory CarMen (INSERM 1060, INRA 1235, INSA), University of Lyon, Faculté de Médecine Lyon-Sud, Chemin du Grand Revoyet, Oullins, France
| | - Emmanuelle Meugnier
- Department of Cell Biology and Morphology, University of Lausanne, Lausanne, Switzerland.
University of Lille Nord de France, European Genomic Institute for Diabetes EGID FR 3508, UMR 8199, Lille, France.
Cell Isolation and Transplantation Center, Department of Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland.
Université catholique de Louvain, Institut de recherche expérimentale et clinique, Pôle d’endocrinologie, diabète et nutrition, Brussels, Belgium.
Montreal Diabetes Research Center and CRCHUM, Montreal, Quebec, Canada.
Departments of Nutrition and Biochemistry, University of Montreal, Montreal, Quebec, Canada.
Center for Integrative Genomics, University of Lausanne, Genopode Building, Lausanne, Switzerland.
Diabetes and Obesity Research Program, Garvan Institute of Medical Research, St. Vincent’s Hospital, Sydney, New South Wales, Australia.
Laboratory CarMen (INSERM 1060, INRA 1235, INSA), University of Lyon, Faculté de Médecine Lyon-Sud, Chemin du Grand Revoyet, Oullins, France
| | - Sophie Rome
- Department of Cell Biology and Morphology, University of Lausanne, Lausanne, Switzerland.
University of Lille Nord de France, European Genomic Institute for Diabetes EGID FR 3508, UMR 8199, Lille, France.
Cell Isolation and Transplantation Center, Department of Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland.
Université catholique de Louvain, Institut de recherche expérimentale et clinique, Pôle d’endocrinologie, diabète et nutrition, Brussels, Belgium.
Montreal Diabetes Research Center and CRCHUM, Montreal, Quebec, Canada.
Departments of Nutrition and Biochemistry, University of Montreal, Montreal, Quebec, Canada.
Center for Integrative Genomics, University of Lausanne, Genopode Building, Lausanne, Switzerland.
Diabetes and Obesity Research Program, Garvan Institute of Medical Research, St. Vincent’s Hospital, Sydney, New South Wales, Australia.
Laboratory CarMen (INSERM 1060, INRA 1235, INSA), University of Lyon, Faculté de Médecine Lyon-Sud, Chemin du Grand Revoyet, Oullins, France
| | - Bernard Thorens
- Department of Cell Biology and Morphology, University of Lausanne, Lausanne, Switzerland.
University of Lille Nord de France, European Genomic Institute for Diabetes EGID FR 3508, UMR 8199, Lille, France.
Cell Isolation and Transplantation Center, Department of Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland.
Université catholique de Louvain, Institut de recherche expérimentale et clinique, Pôle d’endocrinologie, diabète et nutrition, Brussels, Belgium.
Montreal Diabetes Research Center and CRCHUM, Montreal, Quebec, Canada.
Departments of Nutrition and Biochemistry, University of Montreal, Montreal, Quebec, Canada.
Center for Integrative Genomics, University of Lausanne, Genopode Building, Lausanne, Switzerland.
Diabetes and Obesity Research Program, Garvan Institute of Medical Research, St. Vincent’s Hospital, Sydney, New South Wales, Australia.
Laboratory CarMen (INSERM 1060, INRA 1235, INSA), University of Lyon, Faculté de Médecine Lyon-Sud, Chemin du Grand Revoyet, Oullins, France
| | - Marc Prentki
- Department of Cell Biology and Morphology, University of Lausanne, Lausanne, Switzerland.
University of Lille Nord de France, European Genomic Institute for Diabetes EGID FR 3508, UMR 8199, Lille, France.
Cell Isolation and Transplantation Center, Department of Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland.
Université catholique de Louvain, Institut de recherche expérimentale et clinique, Pôle d’endocrinologie, diabète et nutrition, Brussels, Belgium.
Montreal Diabetes Research Center and CRCHUM, Montreal, Quebec, Canada.
Departments of Nutrition and Biochemistry, University of Montreal, Montreal, Quebec, Canada.
Center for Integrative Genomics, University of Lausanne, Genopode Building, Lausanne, Switzerland.
Diabetes and Obesity Research Program, Garvan Institute of Medical Research, St. Vincent’s Hospital, Sydney, New South Wales, Australia.
Laboratory CarMen (INSERM 1060, INRA 1235, INSA), University of Lyon, Faculté de Médecine Lyon-Sud, Chemin du Grand Revoyet, Oullins, France
| | - Domenico Bosco
- Department of Cell Biology and Morphology, University of Lausanne, Lausanne, Switzerland.
University of Lille Nord de France, European Genomic Institute for Diabetes EGID FR 3508, UMR 8199, Lille, France.
Cell Isolation and Transplantation Center, Department of Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland.
Université catholique de Louvain, Institut de recherche expérimentale et clinique, Pôle d’endocrinologie, diabète et nutrition, Brussels, Belgium.
Montreal Diabetes Research Center and CRCHUM, Montreal, Quebec, Canada.
Departments of Nutrition and Biochemistry, University of Montreal, Montreal, Quebec, Canada.
Center for Integrative Genomics, University of Lausanne, Genopode Building, Lausanne, Switzerland.
Diabetes and Obesity Research Program, Garvan Institute of Medical Research, St. Vincent’s Hospital, Sydney, New South Wales, Australia.
Laboratory CarMen (INSERM 1060, INRA 1235, INSA), University of Lyon, Faculté de Médecine Lyon-Sud, Chemin du Grand Revoyet, Oullins, France
| | - Romano Regazzi
- Department of Cell Biology and Morphology, University of Lausanne, Lausanne, Switzerland.
University of Lille Nord de France, European Genomic Institute for Diabetes EGID FR 3508, UMR 8199, Lille, France.
Cell Isolation and Transplantation Center, Department of Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland.
Université catholique de Louvain, Institut de recherche expérimentale et clinique, Pôle d’endocrinologie, diabète et nutrition, Brussels, Belgium.
Montreal Diabetes Research Center and CRCHUM, Montreal, Quebec, Canada.
Departments of Nutrition and Biochemistry, University of Montreal, Montreal, Quebec, Canada.
Center for Integrative Genomics, University of Lausanne, Genopode Building, Lausanne, Switzerland.
Diabetes and Obesity Research Program, Garvan Institute of Medical Research, St. Vincent’s Hospital, Sydney, New South Wales, Australia.
Laboratory CarMen (INSERM 1060, INRA 1235, INSA), University of Lyon, Faculté de Médecine Lyon-Sud, Chemin du Grand Revoyet, Oullins, France
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78
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Iyer A, Lim J, Poudyal H, Reid RC, Suen JY, Webster J, Prins JB, Whitehead JP, Fairlie DP, Brown L. An inhibitor of phospholipase A2 group IIA modulates adipocyte signaling and protects against diet-induced metabolic syndrome in rats. Diabetes 2012; 61:2320-9. [PMID: 22923652 PMCID: PMC3425408 DOI: 10.2337/db11-1179] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Obesity, type 2 diabetes, and cardiovascular disease correlate with infiltration to adipose tissue of different immune cells, with uncertain influences on metabolism. Rats were fed a diet high in carbohydrates and saturated fats to develop diet-induced obesity over 16 weeks. This nutritional overload caused overexpression and secretion of phospholipase A(2) group IIA (pla2g2a) from immune cells in adipose tissue rather than adipocytes, whereas expression of adipose-specific phospholipase A(2) (pla2g16) was unchanged. These immune cells produce prostaglandin E(2) (PGE(2)), which influences adipocyte signaling. We found that a selective inhibitor of human pla2g2a (5-(4-benzyloxyphenyl)-(4S)-(phenyl-heptanoylamino)-pentanoic acid [KH064]) attenuated secretion of PGE(2) from human immune cells stimulated with the fatty acid, palmitic acid, or with lipopolysaccharide. Oral administration of KH064 (5 mg/kg/day) to rats fed the high-carbohydrate, high-fat diet prevented the overexpression of pla2g2a and the increased macrophage infiltration and elevated PGE(2) concentrations in adipose tissue. The treatment also attenuated visceral adiposity and reversed most characteristics of metabolic syndrome, producing marked improvements in insulin sensitivity, glucose intolerance, and cardiovascular abnormalities. We suggest that pla2g2a may have a causal relationship with chronic adiposity and metabolic syndrome and that its inhibition in vivo may be a valuable new approach to treat obesity, type 2 diabetes, and metabolic dysfunction in humans.
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Affiliation(s)
- Abishek Iyer
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - Junxian Lim
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - Hemant Poudyal
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Robert C. Reid
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - Jacky Y. Suen
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
| | - Julie Webster
- Mater Medical Research Institute (MMRI), South Brisbane, Queensland, Australia
| | - Johannes B. Prins
- Mater Medical Research Institute (MMRI), South Brisbane, Queensland, Australia
| | | | - David P. Fairlie
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
- Corresponding authors: Lindsay Brown, , and David Fairlie,
| | - Lindsay Brown
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia
- Department of Biological and Physical Sciences, University of Southern Queensland, Toowoomba, Queensland, Australia
- Corresponding authors: Lindsay Brown, , and David Fairlie,
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79
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Gosmain Y, Cheyssac C, Masson MH, Guérardel A, Poisson C, Philippe J. Pax6 is a key component of regulated glucagon secretion. Endocrinology 2012; 153:4204-15. [PMID: 22778220 DOI: 10.1210/en.2012-1425] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The Pax6 transcription factor is crucial for pancreatic α-cells. Indeed, Pax6-deficient mouse models are characterized by markedly altered α-cell differentiation. Our objective was to investigate the role of Pax6 in glucagon secretion process. We used a Pax6-deficient model in rat primary enriched-α cells with specific small interfering RNA leading to a 70% knockdown of Pax6 expression. We first showed that Pax6 knockdown decreases glucagon biosynthesis as well as glucagon release. Through physiological assays, we demonstrated that the decrease of Pax6 affects specifically acute glucagon secretion in primary α-cell in response to glucose, palmitate, and glucose-dependent insulinotropic peptide (GIP) but not the response to arginine and epinephrine. We identified in Pax6 knockdown model that genes involved in glucagon secretion such as the glucokinase (GCK), G protein-coupled receptor (GPR40), and GIP receptor (GIPR) as well as the corresponding proteins were significantly decreased whereas the insulin receptor (IR) Kir6.2/Sur1, and glucose transporter 1 genes were not affected. We demonstrated that Pax6 directly binds and activates specific elements on the promoter region of the GPR40, GCK, and GIPR genes. Finally, through site-directed mutagenesis experiments, we showed that disruption of Pax6 binding on the GCK, GPR40, and GIPR gene promoters led to specific decreases of their activities in the αTC1.9 glucagon-producing cell line. Hence our results indicate that Pax6 acts on the regulation of glucagon secretion at least through the transcriptional control of GCK, GPR40, and GIPR. We propose that Pax6 is not only critical for glucagon biosynthesis but also for glucagon secretion particularly in response to nutrients.
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MESH Headings
- ATP-Binding Cassette Transporters/genetics
- ATP-Binding Cassette Transporters/metabolism
- Animals
- Cells, Cultured
- Eye Proteins/genetics
- Eye Proteins/metabolism
- Glucagon/metabolism
- Glucokinase/genetics
- Glucokinase/metabolism
- Glucose Transporter Type 1/genetics
- Glucose Transporter Type 1/metabolism
- Homeodomain Proteins/genetics
- Homeodomain Proteins/metabolism
- Immunoprecipitation
- Mutagenesis, Site-Directed
- PAX6 Transcription Factor
- Paired Box Transcription Factors/genetics
- Paired Box Transcription Factors/metabolism
- Potassium Channels, Inwardly Rectifying/genetics
- Potassium Channels, Inwardly Rectifying/metabolism
- Promoter Regions, Genetic/genetics
- Protein Binding
- Rats
- Receptor, Insulin/genetics
- Receptor, Insulin/metabolism
- Receptors, Drug/genetics
- Receptors, Drug/metabolism
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Receptors, Gastrointestinal Hormone/genetics
- Receptors, Gastrointestinal Hormone/metabolism
- Repressor Proteins/genetics
- Repressor Proteins/metabolism
- Sulfonylurea Receptors
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Affiliation(s)
- Yvan Gosmain
- Diabetes Unit, University Hospital, University of Geneva Medical School, 1211 Geneva 14, Switzerland.
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80
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Gosmain Y, Katz LS, Masson MH, Cheyssac C, Poisson C, Philippe J. Pax6 is crucial for β-cell function, insulin biosynthesis, and glucose-induced insulin secretion. Mol Endocrinol 2012; 26:696-709. [PMID: 22403172 DOI: 10.1210/me.2011-1256] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The Pax6 transcription factor is crucial for endocrine cell differentiation and function. Indeed, mutations of Pax6 are associated with a diabetic phenotype and a drastic decrease of insulin-positive cell number. Our aim was to better define the β-cell Pax6 transcriptional network and thus provide further information concerning the role of Pax6 in β-cell function. We developed a Pax6-deficient model in rat primary β-cells with specific small interfering RNA leading to a 75% knockdown of Pax6 expression. Through candidate gene approach, we confirmed that Pax6 controls the mRNA levels of the insulin 1 and 2, Pdx1, MafA, GLUT2, and PC1/3 genes in β-cells. Importantly, we identified new Pax6 target genes coding for GK, Nkx6.1, cMaf, PC2, GLP-1R and GIPR which are all involved in β-cell function. Furthermore, we demonstrated that Pax6 directly binds and activates specific elements on the promoter region of these genes. We also demonstrated that Pax6 knockdown led to decreases in insulin cell content, in insulin processing, and a specific defect of glucose-induced insulin secretion as well as a significant reduction of GLP-1 action in primary β-cells. Our results strongly suggest that Pax6 is crucial for β-cells through transcriptional control of key genes coding for proteins that are involved in insulin biosynthesis and secretion as well as glucose and incretin actions on β-cells. We provide further evidence that Pax6 represents a key element of mature β-cell function.
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Affiliation(s)
- Yvan Gosmain
- Diabetes Unit, Division of Endocrinology, Diabetes, and Nutrition, University Hospital, University of Geneva Medical School, 1211 Geneva 14, Switzerland.
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81
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Turban S, Liu X, Ramage L, Webster SP, Walker BR, Dunbar DR, Mullins JJ, Seckl JR, Morton NM. Optimal elevation of β-cell 11β-hydroxysteroid dehydrogenase type 1 is a compensatory mechanism that prevents high-fat diet-induced β-cell failure. Diabetes 2012; 61:642-52. [PMID: 22315313 PMCID: PMC3282808 DOI: 10.2337/db11-1054] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Type 2 diabetes ultimately results from pancreatic β-cell failure. Abnormally elevated intracellular regeneration of glucocorticoids by the enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) in fat or liver may underlie pathophysiological aspects of the metabolic syndrome. Elevated 11β-HSD1 is also found in pancreatic islets of obese/diabetic rodents and is hypothesized to suppress insulin secretion and promote diabetes. To define the direct impact of elevated pancreatic β-cell 11β-HSD1 on insulin secretion, we generated β-cell-specific, 11β-HSD1-overexpressing (MIP-HSD1) mice on a strain background prone to β-cell failure. Unexpectedly, MIP-HSD1(tg/+) mice exhibited a reversal of high fat-induced β-cell failure through augmentation of the number and intrinsic function of small islets in association with induction of heat shock, protein kinase A, and extracellular signal-related kinase and p21 signaling pathways. 11β-HSD1(-/-) mice showed mild β-cell impairment that was offset by improved glucose tolerance. The benefit of higher β-cell 11β-HSD1 exhibited a threshold because homozygous MIP-HSD1(tg/tg) mice and diabetic Lep(db/db) mice with markedly elevated β-cell 11β-HSD1 levels had impaired basal β-cell function. Optimal elevation of β-cell 11β-HSD1 represents a novel biological mechanism supporting compensatory insulin hypersecretion rather than exacerbating metabolic disease. These findings have immediate significance for current therapeutic strategies for type 2 diabetes.
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Affiliation(s)
- Sophie Turban
- Molecular Metabolism Group, University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, U.K
| | - Xiaoxia Liu
- Molecular Metabolism Group, University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, U.K
| | - Lynne Ramage
- Molecular Metabolism Group, University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, U.K
| | - Scott P. Webster
- Endocrinology Unit, University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, U.K
| | - Brian R. Walker
- Endocrinology Unit, University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, U.K
| | - Donald R. Dunbar
- Bioinformatics Core, University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, U.K
| | - John J. Mullins
- Molecular Physiology, University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, U.K
| | - Jonathan R. Seckl
- Endocrinology Unit, University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, U.K
| | - Nicholas M. Morton
- Molecular Metabolism Group, University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, Queen’s Medical Research Institute, University of Edinburgh, Edinburgh, U.K
- Corresponding author: Nicholas M. Morton,
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82
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Bensellam M, Duvillié B, Rybachuk G, Laybutt DR, Magnan C, Guiot Y, Pouysségur J, Jonas JC. Glucose-induced O₂ consumption activates hypoxia inducible factors 1 and 2 in rat insulin-secreting pancreatic beta-cells. PLoS One 2012; 7:e29807. [PMID: 22235342 PMCID: PMC3250482 DOI: 10.1371/journal.pone.0029807] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Accepted: 12/06/2011] [Indexed: 12/21/2022] Open
Abstract
Background Glucose increases the expression of glycolytic enzymes and other hypoxia-response genes in pancreatic beta-cells. Here, we tested whether this effect results from the activation of Hypoxia-Inducible-factors (HIF) 1 and 2 in a hypoxia-dependent manner. Methodology/Principal Findings Isolated rat islets and insulin-secreting INS-1E cells were stimulated with nutrients at various pO2 values or treated with the HIF activator CoCl2. HIF-target gene mRNA levels and HIF subunit protein levels were measured by real-time RT-PCR, Western Blot and immunohistochemistry. The formation of pimonidazole-protein adducts was used as an indicator of hypoxia. In INS-1E and islet beta-cells, glucose concentration-dependently stimulated formation of pimonidazole-protein adducts, HIF1 and HIF2 nuclear expression and HIF-target gene mRNA levels to a lesser extent than CoCl2 or a four-fold reduction in pO2. Islets also showed signs of HIF activation in diabetic Leprdb/db but not non-diabetic Leprdb/+ mice. In vitro, these glucose effects were reproduced by nutrient secretagogues that bypass glycolysis, and were inhibited by a three-fold increase in pO2 or by inhibitors of Ca2+ influx and insulin secretion. In INS-1E cells, small interfering RNA-mediated knockdown of Hif1α and Hif2α, alone or in combination, indicated that the stimulation of glycolytic enzyme mRNA levels depended on both HIF isoforms while the vasodilating peptide adrenomedullin was a HIF2-specific target gene. Conclusions/Significance Glucose-induced O2 consumption creates an intracellular hypoxia that activates HIF1 and HIF2 in rat beta-cells, and this glucose effect contributes, together with the activation of other transcription factors, to the glucose stimulation of expression of some glycolytic enzymes and other hypoxia response genes.
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Affiliation(s)
- Mohammed Bensellam
- Pôle d′Endocrinologie, Diabète et Nutrition, Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, Brussels, Belgium
| | - Bertrand Duvillié
- INSERM U845, Faculté de Médecine, Research Center Growth and Signalling, Université Paris Descartes, Hôpital Necker, Paris, France
| | - Galyna Rybachuk
- Pôle d′Endocrinologie, Diabète et Nutrition, Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, Brussels, Belgium
| | - D. Ross Laybutt
- Diabetes and Obesity Research Program, Garvan Institute of Medical Research, St. Vincent's Hospital, Sydney, Australia
| | - Christophe Magnan
- Unité de Biologie Fonctionnelle et Adaptative, CNRS-Université Paris Diderot-Paris 7, Paris, France
| | - Yves Guiot
- Pôle de Morphologie, Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, Brussels, Belgium
| | - Jacques Pouysségur
- Institute of Developmental Biology and Cancer Research, University of Nice, CNRS UMR 6543, Centre A. Lacassagne, Nice, France
| | - Jean-Christophe Jonas
- Pôle d′Endocrinologie, Diabète et Nutrition, Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, Brussels, Belgium
- * E-mail:
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83
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Åkerfeldt MC, Laybutt DR. Inhibition of Id1 augments insulin secretion and protects against high-fat diet-induced glucose intolerance. Diabetes 2011; 60:2506-14. [PMID: 21940780 PMCID: PMC3178288 DOI: 10.2337/db11-0083] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
OBJECTIVE The molecular mechanisms responsible for pancreatic β-cell dysfunction in type 2 diabetes remain unresolved. Increased expression of the helix-loop-helix protein Id1 has been found in islets of diabetic mice and in vitro models of β-cell dysfunction. Here, we investigated the role of Id1 in insulin secretion and glucose homeostasis. RESEARCH DESIGN AND METHODS Id1 knockout (Id1(-/-)) and wild-type mice were fed a chow or high-fat diet. Glucose tolerance, insulin tolerance, β-cell mass, insulin secretion, and islet gene expression were assessed. Small interfering RNA (siRNA) was used to silence Id1 in MIN6 cells, and responses to chronic palmitate treatment were assessed. RESULTS Id1(-/-) mice exhibited an improved response to glucose challenge and were almost completely protected against glucose intolerance induced by high-fat diet. This was associated with increased insulin levels and enhanced insulin release from isolated islets, whereas energy intake, body weight, fat pad weight, β-cell mass, and insulin action were unchanged. Islets from Id1(-/-) mice displayed reduced stress gene expression and were protected against high-fat diet-induced downregulation of β-cell gene expression (pancreatic duodenal homeobox-1, Beta2, Glut2, pyruvate carboxylase, and Gpr40). In MIN6 cells, siRNA-mediated inhibition of Id1 enhanced insulin secretion after chronic palmitate treatment and protected against palmitate-mediated loss of β-cell gene expression. CONCLUSIONS These findings implicate Id1 as a negative regulator of insulin secretion. Id1 expression plays an essential role in the etiology of glucose intolerance, insulin secretory dysfunction, and β-cell dedifferentiation under conditions of increased lipid supply.
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85
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Cline GW. Fuel-Stimulated Insulin Secretion Depends upon Mitochondria Activation and the Integration of Mitochondrial and Cytosolic Substrate Cycles. Diabetes Metab J 2011; 35:458-65. [PMID: 22111036 PMCID: PMC3221020 DOI: 10.4093/dmj.2011.35.5.458] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The pancreatic islet β-cell is uniquely specialized to couple its metabolism and rates of insulin secretion with the levels of circulating nutrient fuels, with the mitochondrial playing a central regulatory role in this process. In the β-cell, mitochondrial activation generates an integrated signal reflecting rates of oxidativephosphorylation, Kreb's cycle flux, and anaplerosis that ultimately determines the rate of insulin exocytosis. Mitochondrial activation can be regulated by proton leak and mediated by UCP2, and by alkalinization to utilize the pH gradient to drive substrate and ion transport. Converging lines of evidence support the hypothesis that substrate cycles driven by rates of Kreb's cycle flux and by anaplerosis play an integral role in coupling responsive changes in mitochondrial metabolism with insulin secretion. The components and mechanisms that account for the integrated signal of ATP production, substrate cycling, the regulation of cellular redox state, and the production of other secondary signaling intermediates are operative in both rodent and human islet β-cells.
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Affiliation(s)
- Gary W. Cline
- Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, USA
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86
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Gosmain Y, Cheyssac C, Heddad Masson M, Dibner C, Philippe J. Glucagon gene expression in the endocrine pancreas: the role of the transcription factor Pax6 in α-cell differentiation, glucagon biosynthesis and secretion. Diabetes Obes Metab 2011; 13 Suppl 1:31-8. [PMID: 21824254 DOI: 10.1111/j.1463-1326.2011.01445.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The glucagon gene is expressed in α-cells of the pancreas, L cells of the intestine and the hypothalamus. The determinants of the α-cell-specific expression of the glucagon gene are not fully characterized, although Arx, Pax6 and Foxa2 are critical for α-cell differentiation and glucagon gene expression; in addition, the absence of the β-cell-specific transcription factors Pdx1, Pax4 and Nkx6.1 may allow for the glucagon gene to be expressed. Pax6, along with cMaf and MafB, binds to the DNA control element G(1) which confers α-cell specificity to the promoter and to G(3) and potently activates glucagon gene transcription. In addition, to its direct role on the transcription of the glucagon gene, Pax6 controls several transcription factors involved in the activation of the glucagon gene such as cMaf, MafB and NeuroD1/Beta2 as well as different steps of glucagon biosynthesis and secretion. We conclude that Pax6 independently of Arx and Foxa2 is critical for α-cell function by coordinating glucagon gene expression as well as glucagon biosynthesis and secretion.
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Affiliation(s)
- Y Gosmain
- Division of Endocrinology, Diabetes and Nutrition, University Hospital Geneva, Rue Gabrielle-Perret-Gentil 4, 1211 Geneva 14, Switzerland.
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87
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Ikeda N, Inoguchi T, Sonoda N, Fujii M, Takei R, Hirata E, Yokomizo H, Zheng J, Maeda Y, Kobayashi K, Takayanagi R. Biliverdin protects against the deterioration of glucose tolerance in db/db mice. Diabetologia 2011; 54:2183-91. [PMID: 21614569 DOI: 10.1007/s00125-011-2197-2] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Accepted: 04/12/2011] [Indexed: 01/11/2023]
Abstract
AIMS/HYPOTHESIS We have previously shown a negative correlation between serum bilirubin levels and prevalence of type 2 diabetes, suggesting that bilirubin inhibits development of this disease. To confirm this hypothesis, we investigated whether administration of biliverdin, the precursor of bilirubin, protects against the deterioration of glucose tolerance in db/db mice, a rodent model of type 2 diabetes. METHODS Biliverdin (20 mg/kg daily) was orally administered to 5-week-old db/db mice for 4 weeks. After 4 weeks of treatment, i.p. glucose tolerance and insulin tolerance tests were performed. Insulin content was evaluated by immunostaining and ELISA. Oxidative stress markers (8-hydroxy-2'-deoxyguansosine and dihydroethidium staining) and expression of NADPH oxidase components Pdx1 and Bax were also evaluated in isolated islets. RESULTS Treatment with biliverdin partially prevented worsening of hyperglycaemia and glucose intolerance in db/db mice. This effect was accompanied by a significant increase in insulin content and Pdx1 expression, and a significant decrease of apoptosis and Bax expression in pancreatic islets from db/db mice. At the same time, levels of oxidative stress markers and NADPH oxidase component production in islets were normalised. Biliverdin had little effect on HOMA of insulin resistance or insulin resistance evaluated by insulin tolerance tests. CONCLUSIONS/INTERPRETATION Biliverdin may protect against progressive worsening of glucose tolerance in db/db mice, mainly via inhibition of oxidative stress-induced beta cell damage.
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Affiliation(s)
- N Ikeda
- Department of Internal Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
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Chan JY, Cooney GJ, Biden TJ, Laybutt DR. Differential regulation of adaptive and apoptotic unfolded protein response signalling by cytokine-induced nitric oxide production in mouse pancreatic beta cells. Diabetologia 2011; 54:1766-76. [PMID: 21472432 DOI: 10.1007/s00125-011-2139-z] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Accepted: 03/09/2011] [Indexed: 01/06/2023]
Abstract
AIMS/HYPOTHESIS Pro-inflammatory cytokines such as IL-1β, IFN-γ and TNF-α may contribute to pancreatic beta cell destruction in type 1 diabetes. A mechanism requiring nitric oxide, which is generated by inducible nitric oxide synthase (iNOS), in cytokine-induced endoplasmic reticulum (ER) stress and apoptosis has been proposed. Here, we tested the role of nitric oxide in cytokine-induced ER stress and the subsequent unfolded protein response (UPR) in beta cells. METHODS Isolated islets from wild-type and iNos (also known as Nos2) knockout (iNos ( -/- )) mice, and MIN6 beta cells were incubated with IL-1β, IFN-γ and TNF-α for 24-48 h. N (G)-methyl-L: -arginine was used to inhibit nitric oxide production in MIN6 cells. Protein levels and gene expression were assessed by western blot and real-time RT-PCR. RESULTS In islets and MIN6 cells, inhibition of nitric oxide production had no effect on the generation of ER stress by cytokines, as evidenced by downregulation of Serca2b (also known as Atp2a2) mRNA and increased phosphorylation of PKR-like ER kinase, Jun N-terminal kinase (JNK) and eukaryotic translation initiation factor 2 α subunit. However, nitric oxide regulated the pattern of UPR signalling, which delineates the cellular decision to adapt to ER stress or to undergo apoptosis. Inhibition of nitric oxide production led to reduced expression of pro-apoptotic UPR markers, Chop (also known as Ddit3), Atf3 and Trib3. In contrast, adaptive UPR markers (chaperones, foldases and degradation enhancers) were increased. Further analysis of mouse islets showed that cytokine-induced Chop and Atf3 expression was also dependent on JNK activity. CONCLUSIONS/INTERPRETATION The mechanism by which cytokines induce ER stress in mouse beta cells is independent of nitric oxide production. However, nitric oxide may regulate the switch between adaptive and apoptotic UPR signalling.
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Affiliation(s)
- J Y Chan
- Garvan Institute of Medical Research, St Vincent's Hospital, 384 Victoria St, Darlinghurst, NSW, 2010, Australia
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89
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Reversibility of hyperglycaemia and islet abnormalities in the high fat-fed female ZDF rat model of type 2 diabetes. J Pharmacol Toxicol Methods 2011; 63:15-23. [DOI: 10.1016/j.vascn.2010.04.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2010] [Revised: 03/23/2010] [Accepted: 04/01/2010] [Indexed: 01/09/2023]
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90
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Macdonald FR, Peel JE, Jones HB, Mayers RM, Westgate L, Whaley JM, Poucher SM. The novel sodium glucose transporter 2 inhibitor dapagliflozin sustains pancreatic function and preserves islet morphology in obese, diabetic rats. Diabetes Obes Metab 2010; 12:1004-12. [PMID: 20880347 DOI: 10.1111/j.1463-1326.2010.01291.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
AIMS To investigate whether glucose lowering with the selective sodium glucose transporter 2 (SGLT2) inhibitor dapagliflozin would prevent or reduce the decline of pancreatic function and disruption of normal islet morphology. METHODS Female Zucker diabetic fatty (ZDF) rats, 7-8 weeks old, were placed on high-fat diet. Dapagliflozin (1 mg/kg/day, p.o.) was administered for ∼33 days either from initiation of high-fat diet or when rats were moderately hyperglycaemic. Insulin sensitivity and pancreatic function were evaluated using a hyperglycaemic clamp in anaesthetized animals (n = 5-6); β-cell function was quantified using the disposition index (DI) to account for insulin resistance compensation. Pancreata from a matched subgroup (n = 7-8) were fixed and β-cell mass and islet morphology investigated using immunohistochemical methods. RESULTS Dapagliflozin, administered from initiation of high-fat feeding, reduced the development of hyperglycaemia; after 24 days, blood glucose was 8.6 ± 0.5 vs. 13.3 ± 1.3 mmol/l (p < 0.005 vs. vehicle) and glycated haemoglobin 3.6 ± 0.1 vs. 4.8 ± 0.26% (p < 0.003 vs. vehicle). Dapagliflozin improved insulin sensitivity index: 0.08 ± 0.01 vs. 0.02 ± 0.01 in obese controls (p < 0.03). DI was improved to the level of lean control rats (dapagliflozin 0.29 ± 0.04; obese control 0.15 ± 0.01; lean 0.28 ± 0.01). In dapagliflozin-treated rats, β-cell mass was less variable and significant improvement in islet morphology was observed compared to vehicle-treated rats, although there was no change in mean β-cell mass with dapagliflozin. Results were similar when dapagliflozin treatment was initiated when animals were already moderately hyperglycaemic. CONCLUSION Sustained glucose lowering with dapagliflozin in this model of type 2 diabetes prevented the continued decline in functional adaptation of pancreatic β-cells.
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Affiliation(s)
- F R Macdonald
- CVGI Discovery, AstraZeneca, Alderley Park, Macclesfield, Cheshire, UK
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91
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Zhang C, Wang M, Racine JJ, Liu H, Lin CL, Nair I, Lau J, Cao YA, Todorov I, Atkinson M, Zeng D. Induction of chimerism permits low-dose islet grafts in the liver or pancreas to reverse refractory autoimmune diabetes. Diabetes 2010; 59:2228-36. [PMID: 20530743 PMCID: PMC2927945 DOI: 10.2337/db10-0450] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
OBJECTIVE To test whether induction of chimerism lowers the amount of donor islets required for reversal of diabetes and renders the pancreas a suitable site for islet grafts in autoimmune diabetic mice. RESEARCH DESIGN AND METHODS The required donor islet dose for reversal of diabetes in late-stage diabetic NOD mice after transplantation into the liver or pancreas was compared under immunosuppression or after induction of chimerism. Recipient mice were monitored for blood glucose levels and measured for insulin-secretion capacity. Islet grafts were evaluated for beta-cell proliferation, beta-cell functional gene expression, and revascularization. RESULTS With immunosuppression, transplantation of 1,000, but not 600, donor islets was able to reverse diabetes when transplanted into the liver, but transplantation of 1,000 islets was not able to reverse diabetes when transplanted into the pancreas. In contrast, after induction of chimerism, transplantation of as few as 100 donor islets was able to reverse diabetes when transplanted into either the liver or pancreas. Interestingly, when lower doses (50 or 25) of islets were transplanted, donor islets in the pancreas were much more effective in reversal of diabetes than in the liver, which was associated with higher beta-cell replication rate, better beta-cell functional gene expression, and higher vascular density of graft islets in the pancreas. CONCLUSIONS Induction of chimerism not only provides immune tolerance to donor islets, but also markedly reduces the required amount of donor islets for reversal of diabetes. In addition, this process renders the pancreas a more superior site than the liver for donor islets in autoimmune mice.
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Affiliation(s)
- Chunyan Zhang
- Departments of Diabetes Research and Hematopoietic Cell Transplantation, Beckman Research Institute of City of Hope, Duarte, California
| | - Miao Wang
- Departments of Diabetes Research and Hematopoietic Cell Transplantation, Beckman Research Institute of City of Hope, Duarte, California
| | - Jeremy J. Racine
- Departments of Diabetes Research and Hematopoietic Cell Transplantation, Beckman Research Institute of City of Hope, Duarte, California
- Irell and Manella Graduate School of Biological Sciences of City of Hope, Duarte, California
| | - Hongjun Liu
- Departments of Diabetes Research and Hematopoietic Cell Transplantation, Beckman Research Institute of City of Hope, Duarte, California
| | - Chia-Lei Lin
- Departments of Diabetes Research and Hematopoietic Cell Transplantation, Beckman Research Institute of City of Hope, Duarte, California
| | - Indu Nair
- Departments of Diabetes Research and Hematopoietic Cell Transplantation, Beckman Research Institute of City of Hope, Duarte, California
| | - Joyce Lau
- Eugene and Ruth Roberts Summer Student Academy of City of Hope, Duarte, California
| | - Yu-An Cao
- Stanford University School of Medicine, Stanford, California
| | - Ivan Todorov
- Departments of Diabetes Research and Hematopoietic Cell Transplantation, Beckman Research Institute of City of Hope, Duarte, California
- Irell and Manella Graduate School of Biological Sciences of City of Hope, Duarte, California
| | - Mark Atkinson
- University of Florida College of Medicine, Gainesville, Florida
| | - Defu Zeng
- Departments of Diabetes Research and Hematopoietic Cell Transplantation, Beckman Research Institute of City of Hope, Duarte, California
- Irell and Manella Graduate School of Biological Sciences of City of Hope, Duarte, California
- Corresponding author: Defu Zeng,
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92
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Moritoh Y, Takeuchi K, Hazama M. Combination treatment with alogliptin and voglibose increases active GLP-1 circulation, prevents the development of diabetes and preserves pancreatic beta-cells in prediabetic db/db mice. Diabetes Obes Metab 2010; 12:224-33. [PMID: 20151999 DOI: 10.1111/j.1463-1326.2009.01156.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
AIM Alogliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor, and voglibose, an alpha-glucosidase inhibitor, have different but complementary mechanisms of action on glucagon-like peptide-1 (GLP-1) regulation and glucose-lowering effects. The present study evaluated the chronic effects of combination treatment with alogliptin and voglibose in prediabetic db/db mice. METHODS Alogliptin (0.03%) and voglibose (0.001%) alone or in combination were administered in the diet to prediabetic db/db mice. RESULTS After 3 weeks, voglibose treatment increased GLP-1 secretion (voglibose alone, 1.6-fold; alogliptin plus voglibose, 1.5-fold), while it decreased plasma glucose-dependent insulinotropic polypeptide (GIP) (voglibose alone, -30%; alogliptin plus voglibose, -29%). Alogliptin, voglibose and combination treatment decreased plasma DPP-4 activity by 72, 15 and additively by 80%, respectively, and increased plasma active GLP-1 levels by 4.5-, 1.8- and synergistically by 9.1-fold respectively. Combination treatment increased plasma insulin by 3.6-fold (alogliptin alone, 1.3-fold; voglibose alone, 1.8-fold), decreased plasma glucagon by 30% (alogliptin alone, 11%; voglibose alone, 8%), and prevented the development of diabetes, much more effectively than either agent alone. After 4 weeks, alogliptin, voglibose and combination treatment increased pancreatic insulin content by 1.6-, 3.4- and synergistically by 8.5-fold respectively. Furthermore, combination treatment resulted in an increased expression of insulin, pancreatic and duodenal homeobox 1 (PDX1) and glucose transporter 2 (GLUT2), and maintenance of normal beta/alpha-cell distribution in the pancreatic islet. CONCLUSIONS Chronic treatment with alogliptin in combination with voglibose concurrently increased active GLP-1 circulation, increased insulin secretion, decreased glucagon secretion, prevented the onset of the disease, and preserved pancreatic beta-cells and islet structure in prediabetic db/db mice.
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Affiliation(s)
- Y Moritoh
- Pharmacology Research Laboratories, Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, Osaka, Japan.
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93
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Han J, Liu YQ. Reduction of islet pyruvate carboxylase activity might be related to the development of type 2 diabetes mellitus in Agouti-K mice. J Endocrinol 2010; 204:143-52. [PMID: 19910451 PMCID: PMC2808427 DOI: 10.1677/joe-09-0391] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Pyruvate carboxylase (PC) activity is enhanced in the islets of obese rats, but it is reduced in the islets of type 2 diabetic rats, suggesting the importance of PC in beta-cell adaptation to insulin resistance as well as the possibility that PC reduction might lead to hyperglycemia. However, the causality is currently unknown. We used obese Agouti mice (AyL) as a model to show enhanced beta-cell adaptation, and type 2 diabetic db/db mice as a model to show severe beta-cell failure. After comparison of the two models, a less severe type 2 diabetic Agouti-K (AyK) mouse model was used to show the changes in islet PC activity during the development of type 2 diabetes mellitus (T2DM). AyK mice were separated into two groups: mildly (AyK-M, blood glucose <250 mg/dl) and severely (AyK-S, blood glucose >250 mg/dl) hyperglycemic. Islet PC activity, but not protein level, was increased 1.7-fold in AyK-M mice; in AyK-S mice, islet PC activity and protein level were reduced. All other changes including insulin secretion and islet morphology in AyK-M mice were similar to those observed in AyL mice, but they were worse in AyK-S mice where these parameters closely matched those in db/db mice. In 2-day treated islets, PC activity was inhibited by high glucose but not by palmitate. Our findings suggest that islet PC might play a role in the development of T2DM where reduction of PC activity might be a consequence of mild hyperglycemia and a cause for severe hyperglycemia.
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Affiliation(s)
- J Han
- The Research Institute for Children, Children's Hospital at New Orleans, New Orleans, Louisiana 70118, USA
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94
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Kanda Y, Shimoda M, Hamamoto S, Tawaramoto K, Kawasaki F, Hashiramoto M, Nakashima K, Matsuki M, Kaku K. Molecular mechanism by which pioglitazone preserves pancreatic beta-cells in obese diabetic mice: evidence for acute and chronic actions as a PPARgamma agonist. Am J Physiol Endocrinol Metab 2010; 298:E278-86. [PMID: 19920213 PMCID: PMC2822485 DOI: 10.1152/ajpendo.00388.2009] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Pioglitazone preserves pancreatic beta-cell morphology and function in diabetic animal models. In this study, we investigated the molecular mechanisms by which pioglitazone protects beta-cells in diabetic db/db mice. In addition to the morphological analysis of the islets, gene expression profiles of the pancreatic islet were analyzed using laser capture microdissection and were compared with real-time RT-PCR of db/db and nondiabetic m/m mice treated with or without pioglitazone for 2 wk or 2 days. Pioglitazone treatment (2 wk) ameliorated dysmetabolism, increased islet insulin content, restored glucose-stimulated insulin secretion, and preserved beta-cell mass in db/db mice but had no significant effects in m/m mice. Pioglitazone upregulated genes that promote cell differentiation/proliferation in diabetic and nondiabetic mice. In db/db mice, pioglitazone downregulated the apoptosis-promoting caspase-activated DNase gene and upregulated anti-apoptosis-related genes. The above-mentioned effects of pioglitazone treatment were also observed after 2 days of treatment. By contrast, the oxidative stress-promoting NADPH oxidase gene was downregulated, and antioxidative stress-related genes were upregulated, in db/db mice treated with pioglitazone for 2 wk, rather than 2 days. Morphometric results for proliferative cell number antigen and 4-hydroxy-2-noneal modified protein were consistent with the results of gene expression analysis. The present results strongly suggest that pioglitazone preserves beta-cell mass in diabetic mice mostly by two ways; directly, by acceleration of cell differentiation/proliferation and suppression of apoptosis (acute effect); and indirectly, by deceleration of oxidative stress because of amelioration of the underlying metabolic disorder (chronic effect).
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Affiliation(s)
- Yukiko Kanda
- Diabetes and Endocrine Division, Kawasaki Medical School, Kurashiki, Japan
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95
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Jonas JC, Bensellam M, Duprez J, Elouil H, Guiot Y, Pascal SMA. Glucose regulation of islet stress responses and beta-cell failure in type 2 diabetes. Diabetes Obes Metab 2009; 11 Suppl 4:65-81. [PMID: 19817790 DOI: 10.1111/j.1463-1326.2009.01112.x] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Pancreatic beta-cells exposed to high glucose concentrations display altered gene expression, function, survival and growth that may contribute to the slow deterioration of the functional beta-cell mass in type 2 diabetes. These glucotoxic alterations may result from various types of stress imposed by the hyperglycaemic environment, including oxidative stress, endoplasmic reticulum stress, cytokine-induced apoptosis and hypoxia. The glucose regulation of oxidative stress-response and integrated stress-response genes in cultured rat islets follows an asymmetric V-shaped profile parallel to that of beta-cell apoptosis, with a large increase at low glucose and a moderate increase at high vs. intermediate glucose concentrations. These observations suggest that both types of stress could play a role in the alteration of the functional beta-cell mass under states of prolonged hypoglycaemia and hyperglycaemia. In addition, beta-cell demise under glucotoxic conditions may also result from beta-cell hypoxia and, in vivo, from their exposure to inflammatory cytokines released locally by non-endocrine islet cells. A better understanding of the relative contribution of each type of stress to beta-cell glucotoxicity and of their pathophysiological cause in vivo may lead to new therapeutic strategies to prevent the slow deterioration of the functional beta-cell mass in glucose intolerant and type 2 diabetic patients.
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Affiliation(s)
- J C Jonas
- Université catholique de Louvain, Brussels, Belgium.
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96
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Kondo T, El Khattabi I, Nishimura W, Laybutt DR, Geraldes P, Shah S, King G, Bonner-Weir S, Weir G, Sharma A. p38 MAPK is a major regulator of MafA protein stability under oxidative stress. Mol Endocrinol 2009; 23:1281-90. [PMID: 19407223 DOI: 10.1210/me.2008-0482] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Mammalian MafA/RIPE3b1 is an important glucose-responsive transcription factor that regulates function, maturation, and survival of beta-cells. Increased expression of MafA results in improved glucose-stimulated insulin secretion and beta-cell function. Because MafA is a highly phosphorylated protein, we examined whether regulating activity of protein kinases can increase MafA expression by enhancing its stability. We demonstrate that MafA protein stability in MIN6 cells and isolated mouse islets is regulated by both p38 MAPK and glycogen synthase kinase 3. Inhibiting p38 MAPK enhanced MafA stability in cells grown under both low and high concentrations of glucose. We also show that the N-terminal domain of MafA plays a major role in p38 MAPK-mediated degradation; simultaneous mutation of both threonines 57 and 134 into alanines in MafA was sufficient to prevent this degradation. Under oxidative stress, a condition detrimental to beta-cell function, a decrease in MafA stability was associated with a concomitant increase in active p38 MAPK. Interestingly, inhibiting p38 MAPK but not glycogen synthase kinase 3 prevented oxidative stress-dependent degradation of MafA. These results suggest that the p38 MAPK pathway may represent a common mechanism for regulating MafA levels under oxidative stress and basal and stimulatory glucose concentrations. Therefore, preventing p38 MAPK-mediated degradation of MafA represents a novel approach to improve beta-cell function.
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Affiliation(s)
- Takuma Kondo
- Section of Islet Transplantation and Cell Biology, Joslin Diabetes Center, Department of Medicine, Harvard Medical School, Boston, Massachusetts 02215, USA
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97
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Wang T, Xiao XH, Li WH, Wang H, Sun Q, Yuan T, Yang GH. Effects of glucagon on islet beta cell function in patients with diabetes mellitus. ACTA ACUST UNITED AC 2009; 23:117-20. [PMID: 18686632 DOI: 10.1016/s1001-9294(09)60023-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE To evaluate islet beta cell response to intravenous glucagon (a non-glucose secretagogue) stimulation in diabetes mellitus. METHODS Nineteen patients with type 1 diabetes (T1D) and 131 patients with type 2 diabetes (T2D) were recruited in this study. T2D patients were divided into two groups according to therapy: 36 cases treated with insulin and 95 cases treated with diet or oral therapy. The serum C-peptide levels were determined at fasting and six minutes after intravenous injection of 1 mg of glucagon. RESULTS Both fasting and 6-minute post-glucagon-stimulated C-peptide levels in T1D patients were significantly lower than those of T2D patients (0.76 +/- 0.36 ng/mL vs. 1.81 +/- 0.78 ng/mL, P < 0.05; 0.88 +/- 0.42 ng/mL vs. 3.68 +/- 0.98 ng/mL, P < 0.05). In T1D patients, the C-peptide level after injection of glucagon was similar to the fasting level. In T2D, patients treated with diet or oral drug had a significantly greater fasting and stimulated C-peptide level than those patients received insulin therapy (2.45 +/- 0.93 ng/mL vs. 1.61 +/- 0.68 ng/mL, P < 0.05; 5.26 +/- 1.24 ng/mL vs. 2.15 +/- 0.76 ng/mL, P < 0.05). The serum C-peptide level after glucagon stimulation was positively correlated with C-peptide levels at fasting in all three groups (r = 0.76, P < 0.05). CONCLUSIONS The 6-minute glucagon test is valuable in assessing the function of islet beta cell in patients with diabetes mellitus. It is helpful for diagnosis and treatment of diabetes mellitus.
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Affiliation(s)
- Tong Wang
- Key Laboratory of Endocrinology of Ministry of Health, Department of Endocrinology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100730
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98
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Moritoh Y, Takeuchi K, Asakawa T, Kataoka O, Odaka H. Combining a dipeptidyl peptidase-4 inhibitor, alogliptin, with pioglitazone improves glycaemic control, lipid profiles and beta-cell function in db/db mice. Br J Pharmacol 2009; 157:415-26. [PMID: 19371350 DOI: 10.1111/j.1476-5381.2009.00145.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND AND PURPOSE Alogliptin, a highly selective dipeptidyl peptidase-4 (DPP-4) inhibitor, enhances incretin action and pioglitazone enhances hepatic and peripheral insulin actions. Here, we have evaluated the effects of combining these agents in diabetic mice. EXPERIMENTAL APPROACH Effects of short-term treatment with alogliptin alone (0.01%-0.1% in diet), and chronic combination treatment with alogliptin (0.03% in diet) and pioglitazone (0.0075% in diet) were evaluated in db/db mice exhibiting early stages of diabetes. KEY RESULTS Alogliptin inhibited plasma DPP-4 activity up to 84% and increased plasma active glucagon-like peptide-1 by 4.4- to 4.9-fold. Unexpectedly, alogliptin alone lacked clear efficacy for improving glucose levels. However, alogliptin in combination with pioglitazone clearly enhanced the effects of pioglitazone alone. After 3-4 weeks of treatment, combination treatment increased plasma insulin by 3.8-fold, decreased plasma glucagon by 41%, both of which were greater than each drug alone, and increased plasma adiponectin by 2.4-fold. In addition, combination treatment decreased glycosylated haemoglobin by 2.2%, plasma glucose by 52%, plasma triglycerides by 77% and non-esterified fatty acids by 48%, all of which were greater than each drug alone. Combination treatment also increased expression of insulin and pancreatic and duodenal homeobox 1 (PDX1), maintained normal beta-cell/alpha-cell distribution in islets and restored pancreatic insulin content to levels comparable to non-diabetic mice. CONCLUSIONS AND IMPLICATIONS These results indicate that combination treatment with alogliptin and pioglitazone at an early stage of diabetes improved metabolic profiles and indices that measure beta-cell function, and maintained islet structure in db/db mice, compared with either alogliptin or pioglitazone monotherapy.
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Affiliation(s)
- Y Moritoh
- Pharmacology Research Laboratories I, Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, Osaka 532-8686, Japan
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99
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Fernandes-Santos C, Carneiro RE, de Souza Mendonca L, Aguila MB, Mandarim-de-Lacerda CA. Pan-PPAR agonist beneficial effects in overweight mice fed a high-fat high-sucrose diet. Nutrition 2009; 25:818-27. [PMID: 19268533 DOI: 10.1016/j.nut.2008.12.010] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2008] [Revised: 11/25/2008] [Accepted: 12/11/2008] [Indexed: 12/19/2022]
Abstract
OBJECTIVE We analyzed the effect of peroxisome proliferator-activated receptor (PPAR) agonists on adipose tissue morphology, adiponectin expression, and its relation to glucose and insulin levels in C57BL/6 mice fed a high-fat high-sucrose (HFHS) diet. METHODS Male C57BL/6 mice received one of five diets: standard chow, HFHS chow, or HFHS plus rosiglitazone (PPAR-gamma agonist), fenofibrate (PPAR-alpha agonist), or bezafibrate (pan-PPAR agonist). Diets were administered for 11 wk and medications from week 6 to week 11. Glucose intolerance (GI) and insulin resistance were evaluated by oral glucose tolerance testing and homeostasis model assessment for insulin resistance, respectively. Adipocyte diameter was analyzed in epididymal, inguinal, and retroperitoneal fat pads and by adiponectin immunostain. RESULTS Mice fed the HFHS chow had hyperglycemia, GI, insulin resistance, increased fat pad weight, adipocyte hypertrophy, and decreased adiponectin immunostaining. Rosiglitazone improved GI, insulin sensitiveness, and adiponectin immunostaining, but it resulted in body weight gain, hyperphagia, and adipocyte and heart hypertrophy. Fenofibrate improved all parameters except for fasting glucose and GI. Bezafibrate was the most efficient in decreasing body weight and glucose intolerance. CONCLUSION Activation of PPAR-alpha, -delta, and -gamma together is better than the activation of PPAR-alpha or -gamma alone, because bezafibrate showed a wider range of action on metabolic, morphologic, and biometric alterations due to an HFHS diet in mice.
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100
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Sohn EJ, Kim YS, Kim CS, Lee YM, Kim JS. KIOM-79 prevents apoptotic cell death and AGEs accumulation in retinas of diabetic db/db mice. JOURNAL OF ETHNOPHARMACOLOGY 2009; 121:171-174. [PMID: 19013511 DOI: 10.1016/j.jep.2008.09.036] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2008] [Revised: 09/16/2008] [Accepted: 09/29/2008] [Indexed: 05/27/2023]
Abstract
AIM OF THE STUDY KIOM-79 retards the development of diabetic nephropathy in animal models of type 1 and type 2 diabetes. In this study, we evaluated whether KIOM-79 could prevent apoptotic cell death and advanced glycation end products (AGEs) accumulation in the retinas of diabetic db/db mice. MATERIAL AND METHODS Mice were treated orally with KIOM-79 (150 mg/kg body weight) once daily for 12 weeks. Levels of retinal ganglion cell death were measured by terminal dUTP nick-end labeling (TUNEL) assay. In the retina, the activity of caspase-3 (a marker of apoptosis) and the formation of AGEs were measured by immunohistochemical staining. RESULTS KIOM-79 reduced the number of TUNEL-immunoreactive retinal cells. KIOM-79 attenuated caspase-3 expression and AGEs accumulation in the retina. CONCLUSIONS These data show that KIOM-79 can prevent apoptosis in neuronal cells, AGEs accumulation in the retina, and retard the development of diabetic retinopathy.
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Affiliation(s)
- Eun Jin Sohn
- Department of Herbal Pharmaceutical Development, Korea Institute of Oriental Medicine, 461-24 Jeonmin-dong, Yuseong-gu, Daejeon 305-811, Republic of Korea
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