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Zhang X, St Clair JR, London E, Raleigh DP. Islet Amyloid Polypeptide Membrane Interactions: Effects of Membrane Composition. Biochemistry 2017; 56:376-390. [PMID: 28054763 DOI: 10.1021/acs.biochem.6b01016] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Amyloid formation by islet amyloid polypeptide (IAPP) contributes to β-cell dysfunction in type 2 diabetes. Perturbation of the β-cell membrane may contribute to IAPP-induced toxicity. We examine the effects of lipid composition, salt, and buffer on IAPP amyloid formation and on the ability of IAPP to induce leakage of model membranes. Even low levels of anionic lipids promote amyloid formation and membrane permeabilization. Increasing the percentage of the anionic lipids, 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-l-serine (POPS) or 1,2-dioleoyl-sn-glycero-3-phospho(1'-rac-glycerol), enhances the rate of amyloid formation and increases the level of membrane permeabilization. The choice of zwitterionic lipid has no noticeable effect on membrane-catalyzed amyloid formation but in most cases affects leakage, which tends to decrease in the following order: 1,2-dioleoyl-sn-glycero-3-phosphocholine > 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine > sphingomyelin. Uncharged lipids that increase the level of membrane order weaken the ability of IAPP to induce leakage. Leakage is due predominately to pore formation rather than complete disruption of the vesicles under the conditions used in these studies. Cholesterol at or below physiological levels significantly reduces the rate of vesicle-catalyzed IAPP amyloid formation and decreases the susceptibility to IAPP-induced leakage. The effects of cholesterol on amyloid formation are masked by 25 mol % POPS. Overall, there is a strong inverse correlation between the time to form amyloid and the extent of vesicle leakage. NaCl reduces the rate of membrane-catalyzed amyloid formation by anionic vesicles, but accelerates amyloid formation in solution. The implications for IAPP membrane interactions are discussed, as is the possibility that the loss of phosphatidylserine asymmetry enhances IAPP amyloid formation and membrane damage in vivo via a positive feedback loop.
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Affiliation(s)
- Xiaoxue Zhang
- Department of Chemistry, Stony Brook University , Stony Brook, New York 11794-3400, United States
| | - Johnna R St Clair
- Department of Biochemistry and Cell Biology, Stony Brook University , Stony Brook, New York 11794-5215, United States
| | - Erwin London
- Department of Chemistry, Stony Brook University , Stony Brook, New York 11794-3400, United States.,Department of Biochemistry and Cell Biology, Stony Brook University , Stony Brook, New York 11794-5215, United States
| | - Daniel P Raleigh
- Department of Chemistry, Stony Brook University , Stony Brook, New York 11794-3400, United States.,Graduate Program in Biochemistry and Structural Biology, Stony Brook University , Stony Brook, New York 11794-5215, United States
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102
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Min SH, Yoon JH, Hahn S, Cho YM. Comparison between SGLT2 inhibitors and DPP4 inhibitors added to insulin therapy in type 2 diabetes: a systematic review with indirect comparison meta-analysis. Diabetes Metab Res Rev 2017; 33. [PMID: 27155214 DOI: 10.1002/dmrr.2818] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Revised: 04/21/2016] [Accepted: 04/28/2016] [Indexed: 12/23/2022]
Abstract
BACKGROUND Both sodium glucose cotransporter 2 (SGLT2) inhibitors and dipeptidyl peptidase-4 (DPP4) inhibitors can be used to treat patients with type 2 diabetes mellitus (T2DM) that is inadequately controlled with insulin therapy, and yet there has been no direct comparison of these two inhibitors. METHODS We searched MEDLINE, EMBASE, LILACS, the Cochrane Central Register of Controlled Trials and ClinicalTrials.gov through June 2015. Randomized controlled trials published in English that compare SGLT2 inhibitor plus insulin (SGLT2i/INS) with placebo plus insulin or DPP4 inhibitor plus insulin (DPP4i/INS) with placebo plus insulin in patients with T2DM were selected. Data on the study characteristics, efficacy and safety outcomes were extracted. We compared the efficacy and safety between SGLT2i/INS and DPP4i/INS indirectly with covariates adjustment. Risk of potential bias was assessed. RESULTS Fourteen eligible randomized controlled trials comprising 6980 patients were included (five SGLT2 inhibitor studies and nine DPP4 inhibitor studies). Covariate-adjusted indirect comparison using meta-regression analyses revealed that SGLT2i/INS achieved greater reduction in HbA1c [weighted mean difference (WMD) -0.24%, 95% confidence interval (CI) -0.43 to -0.05%], fasting plasma glucose (WMD -18.0 mg/dL, 95% CI -28.5 to -7.6 mg/dL) and body weight (WMD -2.38 kg, 95% CI -3.18 to -1.58 kg) from baseline than DPP4i/INS without increasing the risk of hypoglycaemia (relative risks 1.19, 95% CI 0.78 to 1.82). CONCLUSIONS Sodium glucose cotransporter 2 inhibitors achieved better glycaemic control and greater weight reduction than DPP4 inhibitors without increasing the risk of hypoglycaemia in patients with T2DM that is inadequately controlled with insulin. There has been no direct comparison of SGLT2 inhibitors and DPP4 inhibitors in patients with T2DM inadequately controlled with insulin therapy. In this study, we performed indirect meta-analysis comparing SGLT2 inhibitors and DPP4 inhibitors added to insulin therapy. Without increasing hypoglycaemia, SGLT2 inhibitors showed better glycaemic control and greater weight reduction than DPP4 inhibitors in patients with T2DM inadequately controlled with insulin. The results of the current study could serve as the best available evidence in selecting oral agents to improve glycaemic control in insulin-treated T2DM patients. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Se Hee Min
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Seoul National University College of Medicine, Seoul, South Korea
| | - Jeong-Hwa Yoon
- Interdisciplinary Program in Medical Informatics, Seoul National University College of Medicine, Seoul, South Korea
| | - Seokyung Hahn
- Department of Medicine, Seoul National University College of Medicine/Biostatistics Division of Medical Research Collaborating Center, Seoul National University Hospital, Seoul, South Korea
| | - Young Min Cho
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Seoul National University College of Medicine, Seoul, South Korea
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103
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Burke SJ, Batdorf HM, Burk DH, Noland RC, Eder AE, Boulos MS, Karlstad MD, Collier JJ. db/ db Mice Exhibit Features of Human Type 2 Diabetes That Are Not Present in Weight-Matched C57BL/6J Mice Fed a Western Diet. J Diabetes Res 2017; 2017:8503754. [PMID: 29038790 PMCID: PMC5606106 DOI: 10.1155/2017/8503754] [Citation(s) in RCA: 93] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 07/24/2017] [Accepted: 07/25/2017] [Indexed: 12/19/2022] Open
Abstract
To understand features of human obesity and type 2 diabetes mellitus (T2D) that can be recapitulated in the mouse, we compared C57BL/6J mice fed a Western-style diet (WD) to weight-matched genetically obese leptin receptor-deficient mice (db/db). All mice were monitored for changes in body composition, glycemia, and total body mass. To objectively compare diet-induced and genetic models of obesity, tissue analyses were conducted using mice with similar body mass. We found that adipose tissue inflammation was present in both models of obesity. In addition, distinct alterations in metabolic flexibility were evident between WD-fed mice and db/db mice. Circulating insulin levels are elevated in each model of obesity, while glucagon was increased only in the db/db mice. Although both WD-fed and db/db mice exhibited adaptive increases in islet size, the db/db mice also displayed augmented islet expression of the dedifferentiation marker Aldh1a3 and reduced nuclear presence of the transcription factor Nkx6.1. Based on the collective results put forth herein, we conclude that db/db mice capture key features of human T2D that do not occur in WD-fed C57BL/6J mice of comparable body mass.
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Affiliation(s)
- Susan J. Burke
- Laboratory of Immunogenetics, Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA
| | - Heidi M. Batdorf
- Laboratory of Islet Biology and Inflammation, Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA
- Skeletal Muscle Metabolism Laboratory, Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA
| | - David H. Burk
- Cell Biology and Bioimaging Core Facility, Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA
| | - Robert C. Noland
- Skeletal Muscle Metabolism Laboratory, Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA
| | - Adrianna E. Eder
- Department of Surgery, Graduate School of Medicine, University of Tennessee Health Science Center, Knoxville, TN 37920, USA
| | - Matthew S. Boulos
- Department of Surgery, Graduate School of Medicine, University of Tennessee Health Science Center, Knoxville, TN 37920, USA
| | - Michael D. Karlstad
- Department of Surgery, Graduate School of Medicine, University of Tennessee Health Science Center, Knoxville, TN 37920, USA
| | - J. Jason Collier
- Laboratory of Islet Biology and Inflammation, Pennington Biomedical Research Center, Baton Rouge, LA 70808, USA
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104
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Efficacy of a combination of high and low dosage of PEGylated FGF-21 in treatment of diabetes in db/db mice. Biomed Pharmacother 2016; 84:97-105. [DOI: 10.1016/j.biopha.2016.09.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 08/29/2016] [Accepted: 09/07/2016] [Indexed: 12/18/2022] Open
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105
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Nath S, Ghosh SK, Choudhury Y. A murine model of type 2 diabetes mellitus developed using a combination of high fat diet and multiple low doses of streptozotocin treatment mimics the metabolic characteristics of type 2 diabetes mellitus in humans. J Pharmacol Toxicol Methods 2016; 84:20-30. [PMID: 27773844 DOI: 10.1016/j.vascn.2016.10.007] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 10/04/2016] [Accepted: 10/19/2016] [Indexed: 01/07/2023]
Abstract
INTRODUCTION A murine model of type 2 diabetes mellitus was used to compare the antidiabetic effects of the dipeptidyl peptidase-4 (DPP4) inhibitor vildagliptin and biguanide, metformin. METHODS Swiss albino mice (n=20 males; n=25 females) were given high fat diet (HFD) ad libitum for 3weeks followed by low dose (40mgkg-1 body weight, bw daily) of streptozotocin (STZ) intraperitoneally five times from the 22nd day of treatment onwards, with HFD continued up to 26th day. Controls (n=15 males; n=15 females) were fed normal balanced diet without administration of STZ. Successful induction of diabetes mellitus was confirmed by testing for fasting blood glucose, intraperitoneal glucose tolerance and intraperitoneal insulin sensitivity. Diabetic mice were administered vildagliptin (10mgkg-1 bw daily) and metformin (50mgkg-1 bw daily) orally for 4weeks. Control, diabetic, vildagliptin and metformin-treated diabetic mice were evaluated for alterations in lipid profile using blood serum and histopathology and oxidative stress using tissues including liver, kidney and heart. RESULTS Diabetic mice showed significant alterations in lipid profile, tissue histopathology, impaired glucose tolerance, lower insulin sensitivity and elevated lipid peroxidation and protein carbonylation, with depressed catalase activity, when compared to age and gender-matched controls. Metformin and vildagliptin ameliorated the abovementioned diabetic conditions, with vildagliptin found to be more effective. DISCUSSION A murine model developed by the combination of HFD and multiple low dose of STZ mimics the metabolic characteristics of type 2 diabetes mellitus in humans, and may be useful for antidiabetic drug screening.
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Affiliation(s)
- Sayantan Nath
- Department of Biotechnology, Assam University, Silchar, 788011, India
| | | | - Yashmin Choudhury
- Department of Biotechnology, Assam University, Silchar, 788011, India.
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Semplici F, Mondragon A, Macintyre B, Madeyski-Bengston K, Persson-Kry A, Barr S, Ramne A, Marley A, McGinty J, French P, Soedling H, Yokosuka R, Gaitan J, Lang J, Migrenne-Li S, Philippe E, Herrera PL, Magnan C, da Silva Xavier G, Rutter GA. Cell type-specific deletion in mice reveals roles for PAS kinase in insulin and glucagon production. Diabetologia 2016; 59:1938-47. [PMID: 27338626 PMCID: PMC4969360 DOI: 10.1007/s00125-016-4025-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 06/01/2016] [Indexed: 12/12/2022]
Abstract
AIMS/HYPOTHESIS Per-Arnt-Sim kinase (PASK) is a nutrient-regulated domain-containing protein kinase previously implicated in the control of insulin gene expression and glucagon secretion. Here, we explore the roles of PASK in the control of islet hormone release, by generating mice with selective deletion of the Pask gene in pancreatic beta or alpha cells. METHODS Floxed alleles of Pask were produced by homologous recombination and animals bred with mice bearing beta (Ins1 (Cre); PaskBKO) or alpha (Ppg (Cre) [also known as Gcg]; PaskAKO) cell-selective Cre recombinase alleles. Glucose homeostasis and hormone secretion in vivo and in vitro, gene expression and islet cell mass were measured using standard techniques. RESULTS Ins1 (Cre)-based recombination led to efficient beta cell-targeted deletion of Pask. Beta cell mass was reduced by 36.5% (p < 0.05) compared with controls in PaskBKO mice, as well as in global Pask-null mice (38%, p < 0.05). PaskBKO mice displayed normal body weight and fasting glycaemia, but slightly impaired glucose tolerance, and beta cell proliferation, after maintenance on a high-fat diet. Whilst glucose tolerance was unaffected in PaskAKO mice, glucose infusion rates were increased, and glucagon secretion tended to be lower, during hypoglycaemic clamps. Although alpha cell mass was increased (21.9%, p < 0.05), glucagon release at low glucose was impaired (p < 0.05) in PaskAKO islets. CONCLUSIONS/INTERPRETATION The findings demonstrate cell-autonomous roles for PASK in the control of pancreatic endocrine hormone secretion. Differences between the glycaemic phenotype of global vs cell type-specific null mice suggest important roles for tissue interactions in the control of glycaemia by PASK.
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Affiliation(s)
- Francesca Semplici
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, Imperial Centre for Translational and Experimental Medicine, Hammersmith Hospital, du Cane Road, London, W12 0NN, UK
| | - Angeles Mondragon
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, Imperial Centre for Translational and Experimental Medicine, Hammersmith Hospital, du Cane Road, London, W12 0NN, UK
| | - Benedict Macintyre
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, Imperial Centre for Translational and Experimental Medicine, Hammersmith Hospital, du Cane Road, London, W12 0NN, UK
| | - Katja Madeyski-Bengston
- AstraZeneca R&D, DECS, AstraZeneca R&D, Mölndal, Sweden
- AstraZeneca R&D, HC3020, AstraZeneca R&D, Mölndal, Sweden
| | - Anette Persson-Kry
- AstraZeneca R&D, DECS, AstraZeneca R&D, Mölndal, Sweden
- AstraZeneca R&D, HC3020, AstraZeneca R&D, Mölndal, Sweden
| | - Sara Barr
- AstraZeneca R&D, DECS, AstraZeneca R&D, Mölndal, Sweden
- AstraZeneca R&D, HC3020, AstraZeneca R&D, Mölndal, Sweden
| | - Anna Ramne
- AstraZeneca R&D, DECS, AstraZeneca R&D, Mölndal, Sweden
- AstraZeneca R&D, HC3020, AstraZeneca R&D, Mölndal, Sweden
| | | | - James McGinty
- Photonics Group, Department of Physics, Imperial College London, London, UK
| | - Paul French
- Photonics Group, Department of Physics, Imperial College London, London, UK
| | - Helen Soedling
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, Imperial Centre for Translational and Experimental Medicine, Hammersmith Hospital, du Cane Road, London, W12 0NN, UK
| | - Ryohsuke Yokosuka
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, Imperial Centre for Translational and Experimental Medicine, Hammersmith Hospital, du Cane Road, London, W12 0NN, UK
| | - Julien Gaitan
- Université de Bordeaux, Institut de Chimie et Biologie des Membranes et des Nano-objets, CNRS UMR 5248, Pessac, France
| | - Jochen Lang
- Université de Bordeaux, Institut de Chimie et Biologie des Membranes et des Nano-objets, CNRS UMR 5248, Pessac, France
| | - Stephanie Migrenne-Li
- Paris Diderot University, Unit of Functional and Adaptive Biology (BFA), CNRS UMR 8251, Paris, France
| | - Erwann Philippe
- Paris Diderot University, Unit of Functional and Adaptive Biology (BFA), CNRS UMR 8251, Paris, France
| | - Pedro L Herrera
- Department of Genetic Medicine and Development, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Christophe Magnan
- Paris Diderot University, Unit of Functional and Adaptive Biology (BFA), CNRS UMR 8251, Paris, France
| | - Gabriela da Silva Xavier
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, Imperial Centre for Translational and Experimental Medicine, Hammersmith Hospital, du Cane Road, London, W12 0NN, UK.
| | - Guy A Rutter
- Section of Cell Biology and Functional Genomics, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, Imperial Centre for Translational and Experimental Medicine, Hammersmith Hospital, du Cane Road, London, W12 0NN, UK.
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Abstract
Carbohydrate, lipid, and protein metabolism are largely controlled by the interplay of various hormones, which includes those secreted by the pancreatic islets of Langerhans. While typically representing only 1% to 2% of the total pancreatic mass, the islets have a remarkable ability to adapt to disparate situations demanding a change in hormone release, such as peripheral insulin resistance. There are many different routes to the onset of insulin resistance, including obesity, lipodystrophy, glucocorticoid excess, and the chronic usage of atypical antipsychotic drugs. All of these situations are coupled to an increase in pancreatic islet size, often with a corresponding increase in insulin production. These adaptive responses within the islets are ultimately intended to maintain glycemic control and to promote macronutrient homeostasis during times of stress. Herein, we review the consequences of specific metabolic trauma that lead to insulin resistance and the corresponding adaptive alterations within the pancreatic islets.
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Affiliation(s)
- Susan J. Burke
- Laboratory of Islet Biology and Inflammation, Pennington Biomedical Research Center, Baton Rouge, LA 70808
| | - Michael D. Karlstad
- Department of Surgery, Graduate School of Medicine, University of Tennessee Health Science Center, Knoxville, TN 37920
| | - J. Jason Collier
- Laboratory of Islet Biology and Inflammation, Pennington Biomedical Research Center, Baton Rouge, LA 70808
- Department of Surgery, Graduate School of Medicine, University of Tennessee Health Science Center, Knoxville, TN 37920
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Satin LS, Ha J, Sherman AS. Islets Transplanted Into the Eye: Do They Improve Our Insight Into Islet Adaptation to Insulin Resistance? Diabetes 2016; 65:2470-2. [PMID: 27555572 PMCID: PMC5001186 DOI: 10.2337/dbi16-0025] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Leslie S Satin
- Department of Pharmacology and Brehm Center for Diabetes Research, University of Michigan Medical School, Ann Arbor, MI Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Joon Ha
- Laboratory of Biological Modeling, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD
| | - Arthur S Sherman
- Laboratory of Biological Modeling, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD
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Retnakaran R, Ye C, Kramer CK, Connelly PW, Hanley AJ, Sermer M, Zinman B. Maternal Serum Prolactin and Prediction of Postpartum β-Cell Function and Risk of Prediabetes/Diabetes. Diabetes Care 2016; 39:1250-8. [PMID: 27208323 DOI: 10.2337/dc16-0043] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 04/04/2016] [Indexed: 02/03/2023]
Abstract
OBJECTIVE The insulin resistance of mid- to late pregnancy poses a physiologic stress test for the pancreatic β-cells, which must respond by markedly increasing their secretion of insulin. This response is achieved through an expansion of β-cell mass induced by the hormones prolactin and human placental lactogen (HPL). Conversely, the furan fatty acid metabolite 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid (CMPF) has recently emerged as a negative regulator of β-cell function in pregnancy. Given their respective roles in the β-cell response to the stress test of gestation, we hypothesized that antepartum prolactin, HPL, and CMPF may relate to a woman's underlying glucoregulatory physiology and hence to her metabolic status after pregnancy. RESEARCH DESIGN AND METHODS Three hundred and sixty-seven women underwent measurement of fasting serum prolactin, HPL, and CMPF in the late-2nd/early-3rd trimester, followed by an oral glucose tolerance test (OGTT) at 3 months postpartum that enabled assessment of glucose tolerance, insulin sensitivity/resistance, and β-cell function (Insulin Secretion-Sensitivity Index-2 [ISSI-2]). RESULTS The postpartum OGTT identified 301 women with normal glucose tolerance (NGT) and 66 with prediabetes or diabetes. Serum prolactin in pregnancy was higher in women with postpartum NGT compared with those with postpartum prediabetes/diabetes (mean 98.2 vs. 80.2 ng/mL, P = 0.0003), whereas HPL and CMPF did not differ between the groups. On multiple linear regression analyses, antepartum prolactin was an independent determinant of postpartum ISSI-2 (β = 0.0016, t = 2.96, P = 0.003). Furthermore, higher serum prolactin in pregnancy independently predicted a lower risk of postpartum prediabetes/diabetes (odds ratio 0.50, 95% CI 0.35-0.72, P = 0.0002). CONCLUSIONS Serum prolactin in pregnancy predicts postpartum β-cell function and risk of prediabetes/diabetes.
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Affiliation(s)
- Ravi Retnakaran
- Leadership Sinai Centre for Diabetes, Mount Sinai Hospital, Toronto, Ontario, Canada Division of Endocrinology, University of Toronto, Toronto, Ontario, Canada Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Chang Ye
- Leadership Sinai Centre for Diabetes, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Caroline K Kramer
- Leadership Sinai Centre for Diabetes, Mount Sinai Hospital, Toronto, Ontario, Canada Division of Endocrinology, University of Toronto, Toronto, Ontario, Canada
| | - Philip W Connelly
- Division of Endocrinology, University of Toronto, Toronto, Ontario, Canada Keenan Research Centre for Biomedical Science of St. Michael's Hospital, Toronto, Ontario, Canada
| | - Anthony J Hanley
- Leadership Sinai Centre for Diabetes, Mount Sinai Hospital, Toronto, Ontario, Canada Division of Endocrinology, University of Toronto, Toronto, Ontario, Canada Department of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada
| | - Mathew Sermer
- Division of Obstetrics and Gynecology, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Bernard Zinman
- Leadership Sinai Centre for Diabetes, Mount Sinai Hospital, Toronto, Ontario, Canada Division of Endocrinology, University of Toronto, Toronto, Ontario, Canada Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
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Retnakaran R, Ye C, Kramer CK, Connelly PW, Hanley AJ, Sermer M, Zinman B. Evaluation of Circulating Determinants of Beta-Cell Function in Women With and Without Gestational Diabetes. J Clin Endocrinol Metab 2016; 101:2683-91. [PMID: 27023450 DOI: 10.1210/jc.2016-1402] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
CONTEXT Gestational diabetes (GDM) arises in women in whom there is insufficient β-cell compensation for the insulin resistance of late pregnancy. The mechanisms underlying both normal antepartum β-cell adaptation and its aberrancy in GDM are unclear. Preclinical studies have suggested that the hormones prolactin and human placental lactogen (HPL) may stimulate β-cell mass, whereas the furan fatty acid metabolite 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid (CMPF) has recently emerged as a potential negative regulator of β-cell function. However, there has been limited study of these factors in humans. OBJECTIVE Our objective was to systematically evaluate HPL, prolactin, and CMPF in relation to glucose homeostasis and β-cell function in women with and without GDM. DESIGN/SETTING/PARTICIPANTS Three-hundred-and-ninety-five women underwent an oral glucose tolerance test in late pregnancy, enabling assessment of GDM status, glycemia (area-under-the-glucose-curve on oral glucose tolerance test [AUCglucose]), β-cell function (Insulin Secretion-Sensitivity Index-2, insulinogenic index/homeostatic model assessment of insulin resistance [HOMA-IR]), insulin sensitivity/resistance (Matsuda index, HOMA-IR), and circulating HPL, prolactin, and CMPF. RESULTS Serum concentrations of HPL, prolactin, and CMPF were similar between women with GDM (n = 105) and women without GDM (n = 290). However, on multiple linear regression analyses, CMPF emerged as a significant predictor of AUCglucose in women with GDM (t = 4.75, P < .0001) but not in their peers (P = .60). Furthermore, CMPF independently predicted lower Insulin Secretion-Sensitivity Index-2 (t = -2.28, P = .02) and lower insulinogenic index/HOMA-IR (t = -2.22, P = .03) in women with GDM but not in the non-GDM group (both P = .93). Neither HPL nor prolactin was significantly associated with AUCglucose, β-cell function, or insulin sensitivity. CONCLUSION CMPF is a potential circulating determinant of β-cell dysfunction and hyperglycemia in women with GDM.
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Affiliation(s)
- Ravi Retnakaran
- Leadership Sinai Centre for Diabetes (R.R., C.Y., C.K.K., A.J.H., B.Z.), Mt Sinai Hospital, Toronto, Ontario, Canada; Division of Endocrinology (R.R., C.K.K., P.W.C., A.J.H., B.Z.), University of Toronto, Toronto, Ontario, Canada; Lunenfeld-Tanenbaum Research Institute (R.R., B.Z.), Mt Sinai Hospital, Toronto, Canada; Keenan Research Centre for Biomedical Science of St. Michael's Hospital (P.W.C.), Toronto, Canada; Department of Nutritional Sciences (A.J.H.), University of Toronto, Toronto, Ontario, Canada; and Division of Obstetrics and Gynecology (M.S.), Mt Sinai Hospital, Toronto, Canada
| | - Chang Ye
- Leadership Sinai Centre for Diabetes (R.R., C.Y., C.K.K., A.J.H., B.Z.), Mt Sinai Hospital, Toronto, Ontario, Canada; Division of Endocrinology (R.R., C.K.K., P.W.C., A.J.H., B.Z.), University of Toronto, Toronto, Ontario, Canada; Lunenfeld-Tanenbaum Research Institute (R.R., B.Z.), Mt Sinai Hospital, Toronto, Canada; Keenan Research Centre for Biomedical Science of St. Michael's Hospital (P.W.C.), Toronto, Canada; Department of Nutritional Sciences (A.J.H.), University of Toronto, Toronto, Ontario, Canada; and Division of Obstetrics and Gynecology (M.S.), Mt Sinai Hospital, Toronto, Canada
| | - Caroline K Kramer
- Leadership Sinai Centre for Diabetes (R.R., C.Y., C.K.K., A.J.H., B.Z.), Mt Sinai Hospital, Toronto, Ontario, Canada; Division of Endocrinology (R.R., C.K.K., P.W.C., A.J.H., B.Z.), University of Toronto, Toronto, Ontario, Canada; Lunenfeld-Tanenbaum Research Institute (R.R., B.Z.), Mt Sinai Hospital, Toronto, Canada; Keenan Research Centre for Biomedical Science of St. Michael's Hospital (P.W.C.), Toronto, Canada; Department of Nutritional Sciences (A.J.H.), University of Toronto, Toronto, Ontario, Canada; and Division of Obstetrics and Gynecology (M.S.), Mt Sinai Hospital, Toronto, Canada
| | - Philip W Connelly
- Leadership Sinai Centre for Diabetes (R.R., C.Y., C.K.K., A.J.H., B.Z.), Mt Sinai Hospital, Toronto, Ontario, Canada; Division of Endocrinology (R.R., C.K.K., P.W.C., A.J.H., B.Z.), University of Toronto, Toronto, Ontario, Canada; Lunenfeld-Tanenbaum Research Institute (R.R., B.Z.), Mt Sinai Hospital, Toronto, Canada; Keenan Research Centre for Biomedical Science of St. Michael's Hospital (P.W.C.), Toronto, Canada; Department of Nutritional Sciences (A.J.H.), University of Toronto, Toronto, Ontario, Canada; and Division of Obstetrics and Gynecology (M.S.), Mt Sinai Hospital, Toronto, Canada
| | - Anthony J Hanley
- Leadership Sinai Centre for Diabetes (R.R., C.Y., C.K.K., A.J.H., B.Z.), Mt Sinai Hospital, Toronto, Ontario, Canada; Division of Endocrinology (R.R., C.K.K., P.W.C., A.J.H., B.Z.), University of Toronto, Toronto, Ontario, Canada; Lunenfeld-Tanenbaum Research Institute (R.R., B.Z.), Mt Sinai Hospital, Toronto, Canada; Keenan Research Centre for Biomedical Science of St. Michael's Hospital (P.W.C.), Toronto, Canada; Department of Nutritional Sciences (A.J.H.), University of Toronto, Toronto, Ontario, Canada; and Division of Obstetrics and Gynecology (M.S.), Mt Sinai Hospital, Toronto, Canada
| | - Mathew Sermer
- Leadership Sinai Centre for Diabetes (R.R., C.Y., C.K.K., A.J.H., B.Z.), Mt Sinai Hospital, Toronto, Ontario, Canada; Division of Endocrinology (R.R., C.K.K., P.W.C., A.J.H., B.Z.), University of Toronto, Toronto, Ontario, Canada; Lunenfeld-Tanenbaum Research Institute (R.R., B.Z.), Mt Sinai Hospital, Toronto, Canada; Keenan Research Centre for Biomedical Science of St. Michael's Hospital (P.W.C.), Toronto, Canada; Department of Nutritional Sciences (A.J.H.), University of Toronto, Toronto, Ontario, Canada; and Division of Obstetrics and Gynecology (M.S.), Mt Sinai Hospital, Toronto, Canada
| | - Bernard Zinman
- Leadership Sinai Centre for Diabetes (R.R., C.Y., C.K.K., A.J.H., B.Z.), Mt Sinai Hospital, Toronto, Ontario, Canada; Division of Endocrinology (R.R., C.K.K., P.W.C., A.J.H., B.Z.), University of Toronto, Toronto, Ontario, Canada; Lunenfeld-Tanenbaum Research Institute (R.R., B.Z.), Mt Sinai Hospital, Toronto, Canada; Keenan Research Centre for Biomedical Science of St. Michael's Hospital (P.W.C.), Toronto, Canada; Department of Nutritional Sciences (A.J.H.), University of Toronto, Toronto, Ontario, Canada; and Division of Obstetrics and Gynecology (M.S.), Mt Sinai Hospital, Toronto, Canada
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111
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Do OH, Gunton JE, Gaisano HY, Thorn P. Changes in beta cell function occur in prediabetes and early disease in the Lepr (db) mouse model of diabetes. Diabetologia 2016; 59:1222-30. [PMID: 27048248 PMCID: PMC4869737 DOI: 10.1007/s00125-016-3942-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 02/29/2016] [Indexed: 01/09/2023]
Abstract
AIMS/HYPOTHESIS Type 2 diabetes is a progressive disease that increases morbidity and the risk of premature death. Glucose dysregulation, such as elevated fasting blood glucose, is observed prior to diabetes onset. A decline in beta cell insulin secretion contributes to the later stages of diabetes, but it is not known what, if any, functional beta cell changes occur in prediabetes and early disease. METHODS The Lepr (db) mouse (age 13-18 weeks) was used as a model of type 2 diabetes and a two-photon granule fusion assay was used to characterise the secretory response of pancreatic beta cells. RESULTS We identified a prediabetic state in db/db mice where the animals responded normally to a glucose challenge but have elevated fasting blood glucose. Isolated islets from prediabetic animals secreted more and were bigger. Insulin secretion, normalised to insulin content, was similar to wild type but basal insulin secretion was elevated. There was increased glucose-induced granule fusion with a high prevalence of granule-granule fusion. The glucose-induced calcium response was not changed but there was altered expression of the exocytic machinery. db/db animals at the next stage of disease had overt glucose intolerance. Isolated islets from these animals had reduced insulin secretion, reduced glucose-induced granule fusion events and decreased calcium responses to glucose. CONCLUSIONS/INTERPRETATION Beta cell function is altered in prediabetes and there are further changes in the progression to early disease.
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Affiliation(s)
- Oanh H Do
- School of Biomedical Sciences, University of Queensland, St Lucia, Brisbane, QLD, 4072, Australia
- Charles Perkins Centre, University of Sydney, John Hopkins Drive, Camperdown, Sydney, NSW, 2050, Australia
| | - Jenny E Gunton
- Westmead Hospital, Sydney, NSW, 2145, Australia
- Westmead Institute for Medical Research, PO Box 412, Westmead, Sydney, NSW, 2145, Australia
| | - Herbert Y Gaisano
- School of Medicine, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Peter Thorn
- School of Biomedical Sciences, University of Queensland, St Lucia, Brisbane, QLD, 4072, Australia.
- Charles Perkins Centre, University of Sydney, John Hopkins Drive, Camperdown, Sydney, NSW, 2050, Australia.
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112
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Xu HZ, Cheng YL, Wang WN, Wu H, Zhang YY, Zang CS, Xu ZG. 12-Lipoxygenase Inhibition on Microalbuminuria in Type-1 and Type-2 Diabetes Is Associated with Changes of Glomerular Angiotensin II Type 1 Receptor Related to Insulin Resistance. Int J Mol Sci 2016; 17:ijms17050684. [PMID: 27164093 PMCID: PMC4881510 DOI: 10.3390/ijms17050684] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 04/18/2016] [Accepted: 04/27/2016] [Indexed: 01/06/2023] Open
Abstract
(1) BACKGROUND: 12-lipoxygenase (12-LO) is involved in the development of diabetic nephropathy (DN). In the present study, we investigated whether 12-LO inhibition may ameliorate type-2 DN (T2DN) by interfering with insulin resistance (IR); (2) METHODS: Rat glomerular mesangial cells, glomeruli and skeletal muscles were isolated and used in this study. Kidney histological changes were confirmed by periodic-acid Schiff staining; mRNA expression was detected by competitive reverse transcription polymerase chain reaction; and the protein level was determined by Western blot and the enzyme-linked immunosorbent assay, respectively; (3) RESULTS: The inhibition of 12-LO attenuated microalbuminuria (MAU) increases in type-2 diabetic rats, but not in type-1 diabetic rats. Infusion of 12(S)-hydroxyeicosatetraenoic acid (12(S)-HETE) significantly increased the expression of angiotensin II (Ang II) and Ang II type 1 receptor (AT1R), but decreased the expression of AT1R-associated protein (ATRAP) in rat glomeruli, compared to the control. An in vitro study revealed that both 12(S)-HETE and insulin upregulated AT1R expression in rat mesangial cells. In the presence of p38 mitogen-activated protein kinase (MAPK) inhibitor, SB202190, the 12(S)-HETE-induced ATRAP reduction was significantly abolished. Interestingly, 12-LO inhibition did not influence AT1R expression in type-1 diabetic rats, but significantly abolished the increased AT1R and Ang II expression in glomeruli of type-2 diabetic rats. Furthermore, the inhibition of 12-LO significantly corrected impaired insulin sensitivity and fast serum insulin level, as well as the p-AMP-activated protein kinase (AMPK) reduction in skeletal muscle of type-2 diabetic rats; (4) CONCLUSION: The inhibition of 12-LO potentially ameliorated MAU by preventing IR through the downregulation of glomerular AT1R expression in T2DN.
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MESH Headings
- 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid/pharmacology
- Albuminuria/etiology
- Albuminuria/metabolism
- Animals
- Arachidonate 12-Lipoxygenase/metabolism
- Cells, Cultured
- Diabetes Mellitus, Type 1/complications
- Diabetes Mellitus, Type 1/metabolism
- Diabetes Mellitus, Type 2/complications
- Diabetes Mellitus, Type 2/metabolism
- Diabetic Nephropathies/metabolism
- Down-Regulation
- Insulin Resistance
- Kidney Glomerulus/drug effects
- Kidney Glomerulus/metabolism
- Lipoxygenase Inhibitors/pharmacology
- Male
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/metabolism
- Protein Kinase Inhibitors/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptor, Angiotensin, Type 1/genetics
- Receptor, Angiotensin, Type 1/metabolism
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Affiliation(s)
- Hong-Zhao Xu
- Department of Nephrology, the First Hospital of Jilin University, Changchun 130021, China.
| | - Yan-Li Cheng
- Department of Nephrology, the First Hospital of Jilin University, Changchun 130021, China.
| | - Wan-Ning Wang
- Department of Nephrology, the First Hospital of Jilin University, Changchun 130021, China.
| | - Hao Wu
- Department of Nephrology, the First Hospital of Jilin University, Changchun 130021, China.
| | - Yuan-Yuan Zhang
- Department of Nephrology, the First Hospital of Jilin University, Changchun 130021, China.
| | - Chong-Sen Zang
- Department of Nephrology, the First Hospital of Jilin University, Changchun 130021, China.
| | - Zhong-Gao Xu
- Department of Nephrology, the First Hospital of Jilin University, Changchun 130021, China.
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113
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Briant L, Salehi A, Vergari E, Zhang Q, Rorsman P. Glucagon secretion from pancreatic α-cells. Ups J Med Sci 2016; 121:113-9. [PMID: 27044683 PMCID: PMC4900066 DOI: 10.3109/03009734.2016.1156789] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 02/16/2016] [Indexed: 11/13/2022] Open
Abstract
Type 2 diabetes involves a ménage à trois of impaired glucose regulation of pancreatic hormone release: in addition to impaired glucose-induced insulin secretion, the release of the hyperglycaemic hormone glucagon becomes dysregulated; these last-mentioned defects exacerbate the metabolic consequences of hypoinsulinaemia and are compounded further by hypersecretion of somatostatin (which inhibits both insulin and glucagon secretion). Glucagon secretion has been proposed to be regulated by either intrinsic or paracrine mechanisms, but their relative significance and the conditions under which they operate are debated. Importantly, the paracrine and intrinsic modes of regulation are not mutually exclusive; they could operate in parallel to control glucagon secretion. Here we have applied mathematical modelling of α-cell electrical activity as a novel means of dissecting the processes that underlie metabolic regulation of glucagon secretion. Our analyses indicate that basal hypersecretion of somatostatin and/or increased activity of somatostatin receptors may explain the loss of adequate counter-regulation under hypoglycaemic conditions, as well as the physiologically inappropriate stimulation of glucagon secretion during hyperglycaemia seen in diabetic patients. We therefore advocate studying the interaction of the paracrine and intrinsic mechanisms; unifying these processes may give a more complete picture of the regulation of glucagon secretion from α-cells than studying the individual parts.
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Affiliation(s)
- Linford Briant
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford, UK;
| | - Albert Salehi
- Metabolic Research, Department of Physiology, Institute of Neuroscience and Physiology, University of Göteborg, Göteborg, Sweden
| | - Elisa Vergari
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford, UK;
| | - Quan Zhang
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford, UK;
| | - Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford, UK;
- Metabolic Research, Department of Physiology, Institute of Neuroscience and Physiology, University of Göteborg, Göteborg, Sweden
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114
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Oetjen E. Regulation of Beta-Cell Function and Mass by the Dual Leucine Zipper Kinase. Arch Pharm (Weinheim) 2016; 349:410-3. [PMID: 27100796 DOI: 10.1002/ardp.201600053] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 03/14/2016] [Accepted: 03/18/2016] [Indexed: 01/09/2023]
Abstract
Diabetes mellitus is one of the most rapidly increasing diseases worldwide, whereby approximately 90-95% of patients suffer from type 2 diabetes. Considering its micro- and macrovascular complications like blindness and myocardial infarction, a reliable anti-diabetic treatment is needed. Maintaining the function and the mass of the insulin producing beta-cells despite elevated levels of beta-cell-toxic prediabetic signals represents a desirable mechanism of action of anti-diabetic drugs. The dual leucine zipper kinase (DLK) inhibits the action of two transcription factors within the beta-cell, thereby interfering with insulin secretion and production and the conservation of beta-cell mass. Furthermore, DLK action is regulated by prediabetic signals. Hence, the inhibition of this kinase might protect beta-cells against beta-cell-toxic prediabetic signals and prevent the development of diabetes. DLK might thus present a novel drug target for the treatment of diabetes mellitus type 2.
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Affiliation(s)
- Elke Oetjen
- Department of Clinical Pharmacology and Toxicology, Pharmacology for Pharmacist's Unit, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Centre for Cardiovascular Research) Partner Site Hamburg/Kiel/Lübeck, Germany.,Institute of Pharmacy, University of Hamburg, Hamburg, Germany
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115
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Wallbach M, Duque Escobar J, Babaeikelishomi R, Stahnke MJ, Blume R, Schröder S, Kruegel J, Maedler K, Kluth O, Kehlenbach RH, Miosge N, Oetjen E. Distinct functions of the dual leucine zipper kinase depending on its subcellular localization. Cell Signal 2016; 28:272-83. [PMID: 26776303 DOI: 10.1016/j.cellsig.2016.01.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 12/20/2015] [Accepted: 01/04/2016] [Indexed: 01/09/2023]
Abstract
The dual leucine zipper kinase DLK induces β-cell apoptosis by inhibiting the transcriptional activity conferred by the β-cell protective transcription factor cAMP response element binding protein CREB. This action might contribute to β-cell loss and ultimately diabetes. Within its kinase domain DLK shares high homology with the mixed lineage kinase (MLK) 3, which is activated by tumor necrosis factor (TNF) α and interleukin (IL)-1β, known prediabetic signals. In the present study, the regulation of DLK in β-cells by these cytokines was investigated. Both, TNFα and IL-1β induced the nuclear translocation of DLK. Mutations within a putative nuclear localization signal (NLS) prevented basal and cytokine-induced nuclear localization of DLK and binding to the importin receptor importin α, thereby demonstrating a functional NLS within DLK. DLK NLS mutants were catalytically active as they phosphorylated their down-stream kinase c-Jun N-terminal kinase to the same extent as DLK wild-type but did neither inhibit CREB-dependent gene transcription nor transcription conferred by the promoter of the anti-apoptotic protein BCL-xL. In addition, the β-cell apoptosis-inducing effect of DLK was severely diminished by mutation of its NLS. In a murine model of prediabetes, enhanced nuclear DLK was found. These data demonstrate that DLK exerts distinct functions, depending on its subcellular localization and thus provide a novel level of regulating DLK action. Furthermore, the prevention of the nuclear localization of DLK as induced by prediabetic signals with consecutive suppression of β-cell apoptosis might constitute a novel target in the therapy of diabetes mellitus.
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Affiliation(s)
- Manuel Wallbach
- Department of Pharmacology, University of Göttingen, Robert-Koch-Str. 40, 37075 Göttingen, Germany
| | - Jorge Duque Escobar
- Department of Clinical Pharmacology and Toxicology, University Medical Center Hamburg Eppendorf, Martinistr. 52, 20246 Hamburg, Germany
| | - Rohollah Babaeikelishomi
- Department of Pharmacology, University of Göttingen, Robert-Koch-Str. 40, 37075 Göttingen, Germany; Department of Clinical Pharmacology and Toxicology, University Medical Center Hamburg Eppendorf, Martinistr. 52, 20246 Hamburg, Germany
| | - Marie-Jeannette Stahnke
- Department of Pharmacology, University of Göttingen, Robert-Koch-Str. 40, 37075 Göttingen, Germany
| | - Roland Blume
- Department of Pharmacology, University of Göttingen, Robert-Koch-Str. 40, 37075 Göttingen, Germany
| | - Sabine Schröder
- Department of Clinical Pharmacology and Toxicology, University Medical Center Hamburg Eppendorf, Martinistr. 52, 20246 Hamburg, Germany
| | - Jenny Kruegel
- Department of Prothetics, Faculty of Medicine, Georg-August-University, GZMB, Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
| | - Kathrin Maedler
- Center for Biomolecular Interactions Bremen, Leobener Str. Im NW2, 28359 Bremen, Germany
| | - Oliver Kluth
- German Institute of Human Nutrition Potsdam-Rehbrücke, Arthur-Scheunert-Allee 114-116, 14558 Nuthetal, Germany
| | - Ralph H Kehlenbach
- Department of Molecular Biology, Faculty of Medicine, Georg-August-University, GZMB, Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
| | - Nicolai Miosge
- Department of Prothetics, Faculty of Medicine, Georg-August-University, GZMB, Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
| | - Elke Oetjen
- Department of Pharmacology, University of Göttingen, Robert-Koch-Str. 40, 37075 Göttingen, Germany; Department of Clinical Pharmacology and Toxicology, University Medical Center Hamburg Eppendorf, Martinistr. 52, 20246 Hamburg, Germany; Institute of Pharmacy, University of Hamburg, Bundesstr. 45, 20146 Hamburg, Germany.
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116
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Pilkington EH, Gurzov EN, Kakinen A, Litwak SA, Stanley WJ, Davis TP, Ke PC. Pancreatic β-Cell Membrane Fluidity and Toxicity Induced by Human Islet Amyloid Polypeptide Species. Sci Rep 2016; 6:21274. [PMID: 26880502 PMCID: PMC4754679 DOI: 10.1038/srep21274] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Accepted: 01/20/2016] [Indexed: 01/22/2023] Open
Abstract
Aggregation of human islet amyloid polypeptide (hIAPP) into fibrils and plaques is associated with pancreatic β-cell loss in type 2 diabetes (T2D). However, due to the rapidness of hIAPP conversion in aqueous phase, exactly which hIAPP species is responsible for the observed toxicity and through what mechanisms remains ambiguous. In light of the importance of understanding hIAPP toxicity for T2D here we show a biophysical scheme based on the use of a lipophilic Laurdan dye for examining MIN6 cell membranes upon exposure to fresh and oligomeric hIAPP as well as mature amyloid. It has been found that all three hIAPP species, especially fresh hIAPP, enhanced membrane fluidity and caused losses in cell viability. The cell generation of reactive oxygen species (ROS), however, was the most pronounced with mature amyloid hIAPP. The correlation between changes in membrane fluidity and cell viability and their lack of correlation with ROS production suggest hIAPP toxicity is elicited through both physical and biochemical means. This study offers a new insight into β-cell toxicity induced by controlled hIAPP species, as well as new biophysical methodologies that may prove beneficial for the studies of T2D as well as neurological disorders.
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Affiliation(s)
- Emily H. Pilkington
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Esteban N. Gurzov
- St Vincent’s Institute of Medical Research, 9 Princes Street, Fitzroy, VIC 3065, Australia
- Department of Medicine, St. Vincent’s Hospital, The University of Melbourne, Melbourne, Australia
| | - Aleksandr Kakinen
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Sara A. Litwak
- St Vincent’s Institute of Medical Research, 9 Princes Street, Fitzroy, VIC 3065, Australia
| | - William J. Stanley
- St Vincent’s Institute of Medical Research, 9 Princes Street, Fitzroy, VIC 3065, Australia
- Department of Medicine, St. Vincent’s Hospital, The University of Melbourne, Melbourne, Australia
| | - Thomas P. Davis
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
- Department of Chemistry, University of Warwick, Gibbet Hill, Coventry, CV4 7AL, United Kingdom
| | - Pu Chun Ke
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
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117
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Alarcon C, Boland BB, Uchizono Y, Moore PC, Peterson B, Rajan S, Rhodes OS, Noske AB, Haataja L, Arvan P, Marsh BJ, Austin J, Rhodes CJ. Pancreatic β-Cell Adaptive Plasticity in Obesity Increases Insulin Production but Adversely Affects Secretory Function. Diabetes 2016; 65:438-50. [PMID: 26307586 PMCID: PMC4747460 DOI: 10.2337/db15-0792] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 08/17/2015] [Indexed: 12/17/2022]
Abstract
Pancreatic β-cells normally produce adequate insulin to control glucose homeostasis, but in obesity-related diabetes, there is a presumed deficit in insulin production and secretory capacity. In this study, insulin production was assessed directly in obese diabetic mouse models, and proinsulin biosynthesis was found to be contrastingly increased, coupled with a significant expansion of the rough endoplasmic reticulum (without endoplasmic reticulum stress) and Golgi apparatus, increased vesicular trafficking, and a depletion of mature β-granules. As such, β-cells have a remarkable capacity to produce substantial quantities of insulin in obesity, which are then made available for immediate secretion to meet increased metabolic demand, but this comes at the price of insulin secretory dysfunction. Notwithstanding, it can be restored. Upon exposing isolated pancreatic islets of obese mice to normal glucose concentrations, β-cells revert back to their typical morphology with restoration of regulated insulin secretion. These data demonstrate an unrealized dynamic adaptive plasticity of pancreatic β-cells and underscore the rationale for transient β-cell rest as a treatment strategy for obesity-linked diabetes.
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Affiliation(s)
- Cristina Alarcon
- Kovler Diabetes Center, Department of Medicine, Section of Endocrinology, Diabetes and Metabolism, The University of Chicago, Chicago, IL
| | - Brandon B Boland
- Kovler Diabetes Center, Department of Medicine, Section of Endocrinology, Diabetes and Metabolism, The University of Chicago, Chicago, IL
| | - Yuji Uchizono
- Kovler Diabetes Center, Department of Medicine, Section of Endocrinology, Diabetes and Metabolism, The University of Chicago, Chicago, IL
| | - Patrick C Moore
- Kovler Diabetes Center, Department of Medicine, Section of Endocrinology, Diabetes and Metabolism, The University of Chicago, Chicago, IL
| | - Bryan Peterson
- Kovler Diabetes Center, Department of Medicine, Section of Endocrinology, Diabetes and Metabolism, The University of Chicago, Chicago, IL
| | - Suryalekha Rajan
- Kovler Diabetes Center, Department of Medicine, Section of Endocrinology, Diabetes and Metabolism, The University of Chicago, Chicago, IL
| | - Olivia S Rhodes
- Kovler Diabetes Center, Department of Medicine, Section of Endocrinology, Diabetes and Metabolism, The University of Chicago, Chicago, IL
| | - Andrew B Noske
- Institute for Molecular Bioscience, Queensland Bioscience Precinct, The University of Queensland, Brisbane, Queensland, Australia
| | - Leena Haataja
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical School, Ann Arbor, MI
| | - Peter Arvan
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan Medical School, Ann Arbor, MI
| | - Bradly J Marsh
- Institute for Molecular Bioscience, Queensland Bioscience Precinct, The University of Queensland, Brisbane, Queensland, Australia
| | - Jotham Austin
- Advanced Electron Microscope Core Facility, The University of Chicago, Chicago, IL
| | - Christopher J Rhodes
- Kovler Diabetes Center, Department of Medicine, Section of Endocrinology, Diabetes and Metabolism, The University of Chicago, Chicago, IL
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118
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Cane MC, Parrington J, Rorsman P, Galione A, Rutter GA. The two pore channel TPC2 is dispensable in pancreatic β-cells for normal Ca²⁺ dynamics and insulin secretion. Cell Calcium 2015; 59:32-40. [PMID: 26769314 PMCID: PMC4751975 DOI: 10.1016/j.ceca.2015.12.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 12/08/2015] [Accepted: 12/21/2015] [Indexed: 12/21/2022]
Abstract
Ca(2+) signals are central to the stimulation of insulin secretion from pancreatic β-cells by glucose and other agents, including glucagon-like peptide-1 (GLP-1). Whilst Ca(2+) influx through voltage-gated Ca(2+) channels on the plasma membrane is a key trigger for glucose-stimulated secretion, mobilisation of Ca(2+) from acidic stores has been implicated in the control of more localised Ca(2+) changes and membrane potential. Nicotinic acid adenine dinucleotide phosphate (NAADP), generated in β-cells in response to high glucose, is a potent mobiliser of these stores, and has been proposed to act through two pore channels (TPC1 and TPC2, murine gene names Tpcn1 and Tpcn2). Whilst the role of TPC1 in the control of Ca(2+) mobilisation and insulin secretion was recently confirmed, conflicting data exist for TPC2. Here, we used the selective and efficient deleter strain, Ins1Cre to achieve β-cell selective deletion of the Tpcn2 gene in mice. βTpcn2 KO mice displayed normal intraperitoneal and oral glucose tolerance, and glucose-stimulated Ca(2+) dynamics and insulin secretion from islets were similarly normal. GLP-1-induced Ca(2+) increases involved an increase in oscillation frequency from 4.35 to 4.84 per minute (p=0.04) at 8mM glucose, and this increase was unaffected by the absence of Tpcn2. The current data thus indicate that TPC2 is not absolutely required for normal glucose- or incretin-stimulated insulin secretion from the β-cell. Our findings suggest that TPC1, whose expression tended to increase in Tpcn2 null islets, might be sufficient to support normal Ca(2+) dynamics in response to stimulation by nutrients or incretins.
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Affiliation(s)
- Matthew C Cane
- Section of Cell Biology and Functional Genomics, Imperial College London, Du Cane Road, W12 0NN London, UK
| | - John Parrington
- Department of Pharmacology, University of Oxford, Mansfield Road, OX1 3QT, UK
| | - Patrik Rorsman
- The Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford OX3 7LJ, UK
| | - Antony Galione
- Department of Pharmacology, University of Oxford, Mansfield Road, OX1 3QT, UK
| | - Guy A Rutter
- Section of Cell Biology and Functional Genomics, Imperial College London, Du Cane Road, W12 0NN London, UK.
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119
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Novel Strategies for Inducing Glycemic Remission during the Honeymoon Phase of Type 2 Diabetes. Can J Diabetes 2015; 39 Suppl 5:S142-7. [DOI: 10.1016/j.jcjd.2015.08.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 07/31/2015] [Accepted: 08/10/2015] [Indexed: 12/19/2022]
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Mitchell RK, Hu M, Chabosseau PL, Cane MC, Meur G, Bellomo EA, Carzaniga R, Collinson LM, Li WH, Hodson DJ, Rutter GA. Molecular Genetic Regulation of Slc30a8/ZnT8 Reveals a Positive Association With Glucose Tolerance. Mol Endocrinol 2015; 30:77-91. [PMID: 26584158 PMCID: PMC4995240 DOI: 10.1210/me.2015-1227] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Zinc transporter 8 (ZnT8), encoded by SLC30A8, is chiefly expressed within pancreatic islet cells, where it mediates zinc (Zn2+) uptake into secretory granules. Although a common nonsynonymous polymorphism (R325W), which lowers activity, is associated with increased type 2 diabetes (T2D) risk, rare inactivating mutations in SLC30A8 have been reported to protect against T2D. Here, we generate and characterize new mouse models to explore the impact on glucose homeostasis of graded changes in ZnT8 activity in the β-cell. Firstly, Slc30a8 was deleted highly selectively in these cells using the novel deleter strain, Ins1Cre. The resultant Ins1CreZnT8KO mice displayed significant (P < .05) impairments in glucose tolerance at 10 weeks of age vs littermate controls, and glucose-induced increases in circulating insulin were inhibited in vivo. Although insulin release from Ins1CreZnT8KO islets was normal, Zn2+ release was severely impaired. Conversely, transgenic ZnT8Tg mice, overexpressing the transporter inducibly in the adult β-cell using an insulin promoter-dependent Tet-On system, showed significant (P < .01) improvements in glucose tolerance compared with control animals. Glucose-induced insulin secretion from ZnT8Tg islets was severely impaired, whereas Zn2+ release was significantly enhanced. Our findings demonstrate that glucose homeostasis in the mouse improves as β-cell ZnT8 activity increases, and remarkably, these changes track Zn2+ rather than insulin release in vitro. Activation of ZnT8 in β-cells might therefore provide the basis of a novel approach to treating T2D.
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Affiliation(s)
- Ryan K Mitchell
- Section of Cell Biology and Functional Genomics (R.K.M., M.H., P.L.C., M.C.C., G.M., E.A.B., D.J.H., G.A.R.), Division of Diabetes, Endocrinology and Metabolism, Imperial Centre for Translational and Experimental Medicine, Imperial College London, London W12 0NN, United Kingdom; Electron Microscopy Unit (R.C., L.M.C.), Francis Crick Institute, Lincoln's Inn Fields, London WC2A 3LY, United Kingdom; and Department of Cell Biology and Biochemistry (W.-H.L.), The University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Ming Hu
- Section of Cell Biology and Functional Genomics (R.K.M., M.H., P.L.C., M.C.C., G.M., E.A.B., D.J.H., G.A.R.), Division of Diabetes, Endocrinology and Metabolism, Imperial Centre for Translational and Experimental Medicine, Imperial College London, London W12 0NN, United Kingdom; Electron Microscopy Unit (R.C., L.M.C.), Francis Crick Institute, Lincoln's Inn Fields, London WC2A 3LY, United Kingdom; and Department of Cell Biology and Biochemistry (W.-H.L.), The University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Pauline L Chabosseau
- Section of Cell Biology and Functional Genomics (R.K.M., M.H., P.L.C., M.C.C., G.M., E.A.B., D.J.H., G.A.R.), Division of Diabetes, Endocrinology and Metabolism, Imperial Centre for Translational and Experimental Medicine, Imperial College London, London W12 0NN, United Kingdom; Electron Microscopy Unit (R.C., L.M.C.), Francis Crick Institute, Lincoln's Inn Fields, London WC2A 3LY, United Kingdom; and Department of Cell Biology and Biochemistry (W.-H.L.), The University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Matthew C Cane
- Section of Cell Biology and Functional Genomics (R.K.M., M.H., P.L.C., M.C.C., G.M., E.A.B., D.J.H., G.A.R.), Division of Diabetes, Endocrinology and Metabolism, Imperial Centre for Translational and Experimental Medicine, Imperial College London, London W12 0NN, United Kingdom; Electron Microscopy Unit (R.C., L.M.C.), Francis Crick Institute, Lincoln's Inn Fields, London WC2A 3LY, United Kingdom; and Department of Cell Biology and Biochemistry (W.-H.L.), The University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Gargi Meur
- Section of Cell Biology and Functional Genomics (R.K.M., M.H., P.L.C., M.C.C., G.M., E.A.B., D.J.H., G.A.R.), Division of Diabetes, Endocrinology and Metabolism, Imperial Centre for Translational and Experimental Medicine, Imperial College London, London W12 0NN, United Kingdom; Electron Microscopy Unit (R.C., L.M.C.), Francis Crick Institute, Lincoln's Inn Fields, London WC2A 3LY, United Kingdom; and Department of Cell Biology and Biochemistry (W.-H.L.), The University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Elisa A Bellomo
- Section of Cell Biology and Functional Genomics (R.K.M., M.H., P.L.C., M.C.C., G.M., E.A.B., D.J.H., G.A.R.), Division of Diabetes, Endocrinology and Metabolism, Imperial Centre for Translational and Experimental Medicine, Imperial College London, London W12 0NN, United Kingdom; Electron Microscopy Unit (R.C., L.M.C.), Francis Crick Institute, Lincoln's Inn Fields, London WC2A 3LY, United Kingdom; and Department of Cell Biology and Biochemistry (W.-H.L.), The University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Raffaella Carzaniga
- Section of Cell Biology and Functional Genomics (R.K.M., M.H., P.L.C., M.C.C., G.M., E.A.B., D.J.H., G.A.R.), Division of Diabetes, Endocrinology and Metabolism, Imperial Centre for Translational and Experimental Medicine, Imperial College London, London W12 0NN, United Kingdom; Electron Microscopy Unit (R.C., L.M.C.), Francis Crick Institute, Lincoln's Inn Fields, London WC2A 3LY, United Kingdom; and Department of Cell Biology and Biochemistry (W.-H.L.), The University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Lucy M Collinson
- Section of Cell Biology and Functional Genomics (R.K.M., M.H., P.L.C., M.C.C., G.M., E.A.B., D.J.H., G.A.R.), Division of Diabetes, Endocrinology and Metabolism, Imperial Centre for Translational and Experimental Medicine, Imperial College London, London W12 0NN, United Kingdom; Electron Microscopy Unit (R.C., L.M.C.), Francis Crick Institute, Lincoln's Inn Fields, London WC2A 3LY, United Kingdom; and Department of Cell Biology and Biochemistry (W.-H.L.), The University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Wen-Hong Li
- Section of Cell Biology and Functional Genomics (R.K.M., M.H., P.L.C., M.C.C., G.M., E.A.B., D.J.H., G.A.R.), Division of Diabetes, Endocrinology and Metabolism, Imperial Centre for Translational and Experimental Medicine, Imperial College London, London W12 0NN, United Kingdom; Electron Microscopy Unit (R.C., L.M.C.), Francis Crick Institute, Lincoln's Inn Fields, London WC2A 3LY, United Kingdom; and Department of Cell Biology and Biochemistry (W.-H.L.), The University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - David J Hodson
- Section of Cell Biology and Functional Genomics (R.K.M., M.H., P.L.C., M.C.C., G.M., E.A.B., D.J.H., G.A.R.), Division of Diabetes, Endocrinology and Metabolism, Imperial Centre for Translational and Experimental Medicine, Imperial College London, London W12 0NN, United Kingdom; Electron Microscopy Unit (R.C., L.M.C.), Francis Crick Institute, Lincoln's Inn Fields, London WC2A 3LY, United Kingdom; and Department of Cell Biology and Biochemistry (W.-H.L.), The University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Guy A Rutter
- Section of Cell Biology and Functional Genomics (R.K.M., M.H., P.L.C., M.C.C., G.M., E.A.B., D.J.H., G.A.R.), Division of Diabetes, Endocrinology and Metabolism, Imperial Centre for Translational and Experimental Medicine, Imperial College London, London W12 0NN, United Kingdom; Electron Microscopy Unit (R.C., L.M.C.), Francis Crick Institute, Lincoln's Inn Fields, London WC2A 3LY, United Kingdom; and Department of Cell Biology and Biochemistry (W.-H.L.), The University of Texas Southwestern Medical Center, Dallas, Texas 75390
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121
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Montefusco F, Pedersen MG. Mathematical modelling of local calcium and regulated exocytosis during inhibition and stimulation of glucagon secretion from pancreatic alpha-cells. J Physiol 2015; 593:4519-30. [PMID: 26236035 DOI: 10.1113/jp270777] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 07/28/2015] [Indexed: 02/06/2023] Open
Abstract
Glucagon secretion from pancreatic alpha-cells is dysregulated in diabetes. Despite decades of investigations of the control of glucagon release by glucose and hormones, the underlying mechanisms are still debated. Recently, mathematical models have been applied to investigate the modification of electrical activity in alpha-cells as a result of glucose application. However, recent studies have shown that paracrine effects such as inhibition of glucagon secretion by glucagon-like peptide 1 (GLP-1) or stimulation of release by adrenaline involve cAMP-mediated effects downstream of electrical activity. In particular, depending of the intracellular cAMP concentration, specific types of Ca(2+) channels are inhibited or activated, which interacts with mobilization of secretory granules. To investigate these aspects of alpha-cell function theoretically, we carefully developed a mathematical model of Ca(2+) levels near open or closed Ca(2+) channels of various types, which was linked to a description of Ca(2+) below the plasma membrane, in the bulk cytosol and in the endoplasmic reticulum. We investigated how the various subcellular Ca(2+) compartments contribute to control of glucagon-exocytosis in response to glucose, GLP-1 or adrenaline. Our studies refine previous modelling studies of alpha-cell function, and provide deeper insight into the control of glucagon secretion.
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Affiliation(s)
- Francesco Montefusco
- Department of Information Engineering, University of Padova, Via Gradenigo 6/B, 35131, Padova, Italy
| | - Morten Gram Pedersen
- Department of Information Engineering, University of Padova, Via Gradenigo 6/B, 35131, Padova, Italy
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122
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Vieira E, Merino B, Quesada I. Role of the clock gene Rev-erbα in metabolism and in the endocrine pancreas. Diabetes Obes Metab 2015; 17 Suppl 1:106-14. [PMID: 26332975 DOI: 10.1111/dom.12522] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 05/01/2015] [Indexed: 01/08/2023]
Abstract
Several hormones are regulated by circadian rhythms to adjust the metabolism to the light/dark cycles and feeding/activity patterns throughout the day. Circadian rhythms are mainly governed by the central clock located in the suprachiasmatic nucleus but also by clocks present in peripheral organs, like the endocrine pancreas. Plasma glucose levels and the main pancreatic hormones insulin and glucagon also exhibit daily variations. Alterations in circadian rhythms are associated with metabolic disturbances and pathologies such as obesity and diabetes. The molecular components of central and peripheral clocks and their regulatory mechanisms are well established. Among the different clock genes, Rev-erbα is considered one of the key links between circadian rhythms and metabolism. Rev-erbα is a critical part of a negative feedback loop in the core circadian clock and modulates the clock oscillatory properties. In addition, Rev-erbα plays an important role in the regulation of lipid and glucose metabolism, thermogenesis, adipocyte and muscle differentiation as well as mitochondrial function. In the endocrine pancreas, Rev-erbα regulates insulin and glucagon secretion and pancreatic β-cell proliferation. In the present review, we discuss all these subjects and, particularly, the role of the clock gene Rev-erbα in the endocrine pancreas.
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Affiliation(s)
- E Vieira
- Department of Cell Biology and Genetic, State University of Maringá, Maringá, Brazil
| | - B Merino
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM) and Instituto de Bioingeniería, Universidad Miguel Hernandez, Elche, Spain
| | - I Quesada
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM) and Instituto de Bioingeniería, Universidad Miguel Hernandez, Elche, Spain
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123
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Abstract
Our understanding of beta cell development and function has increased substantially these past 50 years but much remains to be learned before this knowledge can be put to clinical use. A comprehensive business plan will be necessary to develop a detailed molecular and functional blueprint of the beta cell in health and disease based on an integrated approach involving all necessary research disciplines. This blueprint will provide a platform for the development of novel therapeutic strategies for the treatment of both major forms of diabetes, foremost among them beta cell replacement therapy. This is one of a series of commentaries under the banner '50 years forward', giving personal opinions on future perspectives in diabetes, to celebrate the 50th anniversary of Diabetologia (1965-2015).
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Affiliation(s)
- Philippe A Halban
- Department of Genetic Medicine and Development, University of Geneva Medical Centre, 1 rue Michel-Servet, 1211, Geneva 4, Switzerland,
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124
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Satin LS, Schnell S. Evidence for Residual and Partly Reparable Insulin Secretory Function and Maintained β-Cell Gene Expression in Islets From Patients With Type 1 Diabetes. Diabetes 2015; 64:2335-7. [PMID: 26106195 PMCID: PMC4477347 DOI: 10.2337/db15-0434] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Leslie S Satin
- Department of Pharmacology, Brehm Center for Diabetes Research, University of Michigan Medical School, Ann Arbor, MI
| | - Santiago Schnell
- Department of Molecular & Integrative Physiology, Brehm Center for Diabetes Research, University of Michigan Medical School, Ann Arbor, MI
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125
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Kaihara KA, Dickson LM, Ellenbroek JH, Orr CMD, Layden BT, Wicksteed B. PKA Enhances the Acute Insulin Response Leading to the Restoration of Glucose Control. Diabetes 2015; 64:1688-97. [PMID: 25475437 PMCID: PMC4407848 DOI: 10.2337/db14-1051] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Accepted: 11/24/2014] [Indexed: 12/18/2022]
Abstract
Diabetes arises from insufficient insulin secretion and failure of the β-cell mass to persist and expand. These deficits can be treated with ligands to Gs-coupled G-protein-coupled receptors that raise β-cell cAMP. Here we studied the therapeutic potential of β-cell cAMP-dependent protein kinase (PKA) activity in restoring glucose control using β-caPKA mice. PKA activity enhanced the acute insulin response (AIR) to glucose, which is a primary determinant of the efficacy of glucose clearance. Enhanced AIR improved peripheral insulin action, leading to more rapid muscle glucose uptake. In the setting of pre-established glucose intolerance caused by diet-induced insulin resistance or streptozotocin-mediated β-cell mass depletion, PKA activation enhanced β-cell secretory function to restore glucose control, primarily through augmentation of the AIR. Enhanced AIR and improved glucose control were maintained through 16 weeks of a high-fat diet and aging to 1 year. Importantly, improved glucose tolerance did not increase the risk for hypoglycemia, nor did it rely upon hyperinsulinemia or β-cell hyperplasia, although PKA activity was protective for β-cell mass. These data highlight that improving β-cell function through the activation of PKA has a large and underappreciated capacity to restore glucose control with minimal risk for adverse side effects.
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Affiliation(s)
- Kelly A Kaihara
- Kovler Diabetes Center, The University of Chicago, Chicago, IL Committee for Molecular Metabolism and Nutrition, The University of Chicago, Chicago, IL Section of Adult and Pediatric Endocrinology, Diabetes, and Metabolism, Department of Medicine, The University of Chicago, Chicago, IL
| | - Lorna M Dickson
- Kovler Diabetes Center, The University of Chicago, Chicago, IL Section of Adult and Pediatric Endocrinology, Diabetes, and Metabolism, Department of Medicine, The University of Chicago, Chicago, IL
| | - Johanne H Ellenbroek
- Kovler Diabetes Center, The University of Chicago, Chicago, IL Section of Adult and Pediatric Endocrinology, Diabetes, and Metabolism, Department of Medicine, The University of Chicago, Chicago, IL
| | - Caitlin M D Orr
- Kovler Diabetes Center, The University of Chicago, Chicago, IL Committee for Molecular Metabolism and Nutrition, The University of Chicago, Chicago, IL Section of Adult and Pediatric Endocrinology, Diabetes, and Metabolism, Department of Medicine, The University of Chicago, Chicago, IL
| | - Brian T Layden
- Division of Endocrinology, Metabolism, and Molecular Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL Jesse Brown Veterans Affairs Medical Center, Chicago, IL
| | - Barton Wicksteed
- Kovler Diabetes Center, The University of Chicago, Chicago, IL Committee for Molecular Metabolism and Nutrition, The University of Chicago, Chicago, IL Section of Adult and Pediatric Endocrinology, Diabetes, and Metabolism, Department of Medicine, The University of Chicago, Chicago, IL
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126
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Stein CM, Kramer CK, Zinman B, Choi H, Opsteen C, Retnakaran R. Clinical predictors and time course of the improvement in β-cell function with short-term intensive insulin therapy in patients with Type 2 diabetes. Diabet Med 2015; 32:645-52. [PMID: 25495067 DOI: 10.1111/dme.12671] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Revised: 09/26/2014] [Accepted: 12/08/2014] [Indexed: 11/29/2022]
Abstract
AIMS In patients with Type 2 diabetes, a short course of intensive insulin therapy can improve β-cell function and even induce transient remission of diabetes. However, not all patients respond to this therapy. Although the achievement of fasting glucose < 7.0 mmol/l one day after stopping intensive insulin therapy can identify patients in whom β-cell function has improved, we sought to determine clinical predictors for the early identification of such responders and the time course of response. METHODS We pooled data from two studies in which 97 patients with Type 2 diabetes mellitus (median 3 years duration) and HbA1c 51 ± 8.7 mmol/mol (6.8 ± 0.8%) underwent 4-8 weeks of intensive insulin therapy, consisting of basal detemir and pre-meal insulin aspart. They were classified as responders (n = 74) or non-responders (n = 23), defined by the achievement of fasting glucose < 7.0 mmol/l after stopping intensive insulin therapy. RESULTS On logistic regression analyses, duration of diabetes (odds ratio [OR] = 0.72, 95% confidence interval [CI] 0.56-0.92, P = 0.009) and baseline fasting glucose (OR = 0.40, 95% CI 0.24-0.68, P = 0.001) emerged as predictors of the likelihood of responding. Ninety per cent of patients with duration ≤ 4 years and fasting glucose ≤ 8.0 mmol/l responded to intensive insulin therapy. Despite having lower glucose levels during intensive insulin therapy, responders had less hypoglycaemia than non-responders (median 0.3 vs. 1.6 episodes/week, P < 0.0001), with rates of hypoglycaemia diverging sharply from the third week onwards. CONCLUSION At baseline, shorter duration of diabetes and lower fasting glucose can identify patients most likely to benefit from short-term intensive insulin therapy. Most importantly, during therapy, responders had less hypoglycaemia from the third week onwards, despite lower glycaemia, suggesting that 2 weeks of intensive insulin therapy may be needed to improve endogenous islet function.
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Affiliation(s)
- C M Stein
- Sinai Centre for Diabetes, Mount Sinai Hospital, Toronto, Canada
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127
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Pancreatic β-cell identity, glucose sensing and the control of insulin secretion. Biochem J 2015; 466:203-18. [PMID: 25697093 DOI: 10.1042/bj20141384] [Citation(s) in RCA: 251] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Insulin release from pancreatic β-cells is required to maintain normal glucose homoeostasis in man and many other animals. Defective insulin secretion underlies all forms of diabetes mellitus, a disease currently reaching epidemic proportions worldwide. Although the destruction of β-cells is responsible for Type 1 diabetes (T1D), both lowered β-cell mass and loss of secretory function are implicated in Type 2 diabetes (T2D). Emerging results suggest that a functional deficiency, involving de-differentiation of the mature β-cell towards a more progenitor-like state, may be an important driver for impaired secretion in T2D. Conversely, at least in rodents, reprogramming of islet non-β to β-cells appears to occur spontaneously in models of T1D, and may occur in man. In the present paper, we summarize the biochemical properties which define the 'identity' of the mature β-cell as a glucose sensor par excellence. In particular, we discuss the importance of suppressing a group of 11 'disallowed' housekeeping genes, including Ldha and the monocarboxylate transporter Mct1 (Slc16a1), for normal nutrient sensing. We then survey the changes in the expression and/or activity of β-cell-enriched transcription factors, including FOXO1, PDX1, NKX6.1, MAFA and RFX6, as well as non-coding RNAs, which may contribute to β-cell de-differentiation and functional impairment in T2D. The relevance of these observations for the development of new approaches to treat T1D and T2D is considered.
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128
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Ehses JA, Donath MY. Targeting 12-lipoxygenase as a novel strategy to combat the effects of inflammation on beta cells in diabetes. Diabetologia 2015; 58:425-8. [PMID: 25537834 DOI: 10.1007/s00125-014-3482-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 12/04/2014] [Indexed: 01/24/2023]
Abstract
Inflammation is a pathological feature of the pancreatic islet in type 1 and 2 diabetes, contributing to islet endocrine cell failure and the onset of hyperglycaemia in both diseases. Indeed, numerous immune targets have recently been found to be altered in type 2 diabetes, but few have yet to be translated to the clinic. Taylor-Fishwick and colleagues aimed to change this by performing proof-of-concept studies investigating the efficacy of small molecule inhibitors of 12-lipoxygenase in rodent and human beta cells exposed to proinflammatory cytokines. The results of these studies, published in this issue of Diabetologia (DOI: 10.1007/s00125-014-3452-0), build on a wealth of preclinical data that have implicated 12-lipoxygenase in rodent models of type 1 and 2 diabetes. While there remain some unanswered mechanistic questions regarding how cytokines regulate 12-lipoxygenase activation and the downstream consequences of activation, it is hoped that future studies with newly identified selective inhibitors may overcome the in vitro limitations of this study and allow for the eventual clinical translation of these highly interesting findings.
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Affiliation(s)
- Jan A Ehses
- Faculty of Medicine, Department of Surgery and Department of Cellular & Physiological Sciences, The University of British Columbia, Child & Family Research Institute, Room A4-183, 950W 28th Avenue, Vancouver, BC, Canada, V5Z 4H4,
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129
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Kaiser D, Oetjen E. Something old, something new and something very old: drugs for treating type 2 diabetes. Br J Pharmacol 2015; 171:2940-50. [PMID: 24641580 DOI: 10.1111/bph.12624] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Revised: 01/13/2014] [Accepted: 01/30/2014] [Indexed: 12/28/2022] Open
Abstract
Diabetes mellitus belongs to the most rapidly increasing diseases worldwide. Approximately 90-95% of these patients suffer from type 2 diabetes mellitus, which is characterized by peripheral insulin resistance and the progressive loss of beta-cell function and mass. Considering the complications of this chronic disease, a reliable anti-diabetic treatment is indispensable. An ideal oral anti-diabetic drug should not only correct glucose homeostasis but also preserve or even augment beta-cell function and mass, ameliorate the subclinical inflammation present under insulin-resistant conditions and prevent the macro- and microvascular consequences of diabetes in order to reduce the mortality. Despite the many anti-diabetic drugs already in use, there is an ongoing research for additional drugs, guided by different concepts of the pathogenesis of type 2 diabetes. This review will briefly summarize current oral anti-diabetic drugs. In addition, emerging strategies for the treatment of diabetes will be described, among them the inhibition of glucagon action and anti-inflammatory drugs. Their suitability as 'ideal anti-diabetic drugs' will be discussed.
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Affiliation(s)
- D Kaiser
- Department of Clinical Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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130
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Abstract
SLC30A8 encodes the secretory granule-resident and largely endocrine pancreas-restricted zinc transporter ZnT8. Interest in this gene product was sparked amongst diabetologists in 2007 when the first genome-wide association study for type 2 diabetes identified polymorphisms in SLC30A8 as affecting disease risk. Thus, the common polymorphism rs13266634 was associated with lowered beta cell function and a 14% increase in diabetes abundance per risk (C) allele. This non-synonymous variant encodes a tryptophan-to-arginine switch at position 325 in the protein's intracellular carboxy-terminal domain, resulting in reduced zinc transport activity and, consequently, decreased intragranular zinc levels. Whereas insulin secretion from isolated islets is most often increased in mice inactivated for Slc30a8, null animals usually show impaired glucose tolerance and lowered circulating insulin. Since Slc30a8 null animals display little, if any, zinc secretion from islets, the lower plasma insulin levels could be explained by increased hepatic clearance as a result of lowered local zinc levels, or less efficient insulin action on target tissues. Despite the emerging consensus on the role of ZnT8 in glucose homeostasis, a recent genetic study in humans has unexpectedly identified loss-of-function SLC30A8 mutants that are associated with protection from diabetes. Here, we attempt to reconcile these apparently contradictory findings, implicating (1) differing degrees of inhibition of ZnT8 activity in carriers of common variants vs rare loss-of-function forms, (2) effects dependent on age or hypoxic beta cell stress. We propose that these variables conspire to affect both the size and the direction of the effect of SLC30A8 risk alleles in man.
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Affiliation(s)
- Guy A Rutter
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial Centre for Translational and Experimental Medicine, Hammersmith Hospital, Imperial College London, Du Cane Road, London, W12 ONN, UK,
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131
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Sato Y, Oka R, Nakasone Y, Katakura M, Yamauchi K, Aizawa T. Impact of one-hour postchallenge glucose on the relationship between insulin sensitivity and secretion. Endocr J 2015; 62:573-83. [PMID: 26052138 DOI: 10.1507/endocrj.ej15-0122] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The impact of postchallenge glucose on the relationship between insulin sensitivity (SI) and secretion (β) is unknown. We analyzed data from 2,264 health examinees (male/female 1,524/740, median age 54 yrs) with normal glucose tolerance (NGT, n = 1,623), non-diabetic hyperglycemia (NDH, n = 555), or diabetes (DM, n = 86) using OGTT-derived indices of SI (insulin sensitivity index [ISI]-Matsuda, 1/HOMA-IR, and 1/fasting IRI) and β (δIRI0-30/δPG0-30, and Stumvoll 1st [Stumvoll-1] and 2nd [Stumvoll-2] phases). The combination of 1/HOMA-IR and Stumvoll-1 recapitulated the hyperbolic SI-β relationship with the slope of the fitted line -1.000 in NGT subjects, and therefore it was utilized in the following analysis of the SI-β correlation. In multiple regression analysis of the relationship between SI and β, an independent correlation was found for 1 h-plasma glucose (PG; PG60) but not for 2 h-PG. When the NGT subjects were grouped by PG60 quartile (Q), the fitted line was flat in Q1 but progressively steeper from Q2 to Q4, with a slope (95%CI) of -0.663 (-0.726~-0.605), -0.680 (-0.745~-0.622), -0.847 (-0.922~-0.779), and -1.259 (-1.370~-1.158) (P for trend < 0.05). The fitted line steepened further in the NDH and DM groups, with a slope of -1.545 and -1.915, respectively (P < 0.01 for the difference). The intercept of the fitted line for SI-β correlation was also progressively lower across the PG60 Q for NGT, NDH, and DM. In conclusion, using the 1/HOMA-IR-Stumvoll-1 pair for an analysis of the SI-β relationship, elevated PG60 was associated with steepening and downward shifting of the fitted line for the SI-β correlation. The finding suggests impaired beta cell function.
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Affiliation(s)
- Yuka Sato
- Diabetes Center, Aizawa Hospital, Matsumoto 390-8510, Japan
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132
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Eng C, Kramer CK, Zinman B, Retnakaran R. Glucagon-like peptide-1 receptor agonist and basal insulin combination treatment for the management of type 2 diabetes: a systematic review and meta-analysis. Lancet 2014; 384:2228-34. [PMID: 25220191 DOI: 10.1016/s0140-6736(14)61335-0] [Citation(s) in RCA: 282] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND Combination treatment with a glucagon-like peptide-1 (GLP-1) agonist and basal insulin has been proposed as a treatment strategy for type 2 diabetes that could provide robust glucose-lowering capability with low risk of hypoglycaemia or weight gain. We thus did a systematic review and meta-analysis of randomised controlled trials to assess the effect of this combination treatment on glycaemic control, hypoglycaemia, and weight gain in patients with type 2 diabetes. METHODS We systematically searched PubMed, Embase, Cochrane, Web of Knowledge, FDA.gov, and ClinicalTrials.gov for randomised controlled trials (published between Jan 1, 1950, and July 29, 2014; no language restrictions) comparing GLP-1 agonist and basal insulin combination treatment to other anti-diabetic treatments. Our main endpoints were glycaemic control, hypoglycaemia, and change in weight. We assessed pooled data by use of a random-effects model. FINDINGS Of 2905 identified studies, 15 were eligible and were included in our analysis (N=4348 participants). Compared with other anti-diabetic treatments, GLP-1 agonist and basal insulin combination treatment yielded an improved mean reduction in glycated haemoglobin (HbA1c) of -0·44% (95% CI -0·60 to -0·29), an improved likelihood of achieving the target HbA1c of 7·0% or lower (relative risk [RR] 1·92; 95% CI 1·43 to 2·56), no increased relative risk of hypoglycaemia (0·99; 0·76 to 1·29), and a mean reduction in weight of -3·22 kg (-4·90 to -1·54). Furthermore, compared with basal-bolus insulin regimens, the combination treatment yielded a mean reduction in HbA1c of -0·1% (-0·17 to -0·02), with lower relative risk of hypoglycaemia (0·67, 0·56 to 0·80), and reduction in mean weight (-5·66 kg; -9·8 to -1·51). INTERPRETATION GLP-1 agonist and basal insulin combination treatment can enable achievement of the ideal trifecta in diabetic treatment: robust glycaemic control with no increased hypoglycaemia or weight gain. This combination is thus a potential therapeutic strategy that could improve the management of patients with type 2 diabetes. FUNDING None.
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Affiliation(s)
- Conrad Eng
- Leadership Sinai Centre for Diabetes, Mount Sinai Hospital, Toronto, ON, Canada
| | - Caroline K Kramer
- Leadership Sinai Centre for Diabetes, Mount Sinai Hospital, Toronto, ON, Canada; Division of Endocrinology, University of Toronto, Toronto, ON, Canada
| | - Bernard Zinman
- Leadership Sinai Centre for Diabetes, Mount Sinai Hospital, Toronto, ON, Canada; Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada; Division of Endocrinology, University of Toronto, Toronto, ON, Canada
| | - Ravi Retnakaran
- Leadership Sinai Centre for Diabetes, Mount Sinai Hospital, Toronto, ON, Canada; Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, Canada; Division of Endocrinology, University of Toronto, Toronto, ON, Canada.
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133
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Retnakaran R, Kramer CK, Choi H, Swaminathan B, Zinman B. Liraglutide and the preservation of pancreatic β-cell function in early type 2 diabetes: the LIBRA trial. Diabetes Care 2014; 37:3270-8. [PMID: 25249651 DOI: 10.2337/dc14-0893] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Clinical studies evaluating the effects of medications on β-cell function in type 2 diabetes (T2DM) are compromised by an inability to determine the actual baseline degree of β-cell dysfunction independent of the reversible dysfunction induced by hyperglycemia (glucotoxicity). Short-term intensive insulin therapy (IIT) is a strategy for eliminating glucotoxicity before randomization. This study determined whether liraglutide can preserve β-cell function over 48 weeks in early T2DM following initial elimination of glucotoxicity with IIT. RESEARCH DESIGN AND METHODS In this double-blind, randomized, placebo-controlled trial, 51 patients with T2DM of 2.6 ± 1.9 years' duration and an A1C of 6.8 ± 0.8% (51 ± 8.7 mmol/mol) completed 4 weeks of IIT before randomization to daily subcutaneous liraglutide or placebo injection, with serial assessment of β-cell function by Insulin Secretion-Sensitivity Index-2 (ISSI-2) on oral glucose tolerance test performed every 12 weeks. RESULTS The primary outcome of baseline-adjusted ISSI-2 at 48 weeks was higher in the liraglutide group than in the placebo group (339.8 ± 27.8 vs. 229.3 ± 28.4, P = 0.008). Baseline-adjusted HbA1c at 48 weeks was lower in the liraglutide group (6.2 ± 0.1% vs. 6.6 ± 0.1%, P = 0.055) (44 ± 1.1 vs. 49 ± 1.1 mmol/mol). At each quarterly assessment, >50% of participants on liraglutide had an HbA1c ≤6.0% (42 mmol/mol) and glucose tolerance in the nondiabetic range. Despite this level of glycemic control, no difference was found in the incidence of hypoglycemia between the liraglutide and placebo groups (P = 0.61). Two weeks after stopping treatment, however, the beneficial effect on ISSI-2 of liraglutide versus placebo was entirely lost (191.9 ± 24.7 vs. 238.1 ± 25.2, P = 0.20). CONCLUSIONS Liraglutide provides robust enhancement of β-cell function that is sustained over 48 weeks in early T2DM but lost upon cessation of therapy.
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Affiliation(s)
- Ravi Retnakaran
- Leadership Sinai Centre for Diabetes, Mount Sinai Hospital, Toronto, Ontario, Canada Division of Endocrinology, University of Toronto, Toronto, Ontario, Canada Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Caroline K Kramer
- Leadership Sinai Centre for Diabetes, Mount Sinai Hospital, Toronto, Ontario, Canada Division of Endocrinology, University of Toronto, Toronto, Ontario, Canada
| | - Haysook Choi
- Leadership Sinai Centre for Diabetes, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Balakumar Swaminathan
- Leadership Sinai Centre for Diabetes, Mount Sinai Hospital, Toronto, Ontario, Canada
| | - Bernard Zinman
- Leadership Sinai Centre for Diabetes, Mount Sinai Hospital, Toronto, Ontario, Canada Division of Endocrinology, University of Toronto, Toronto, Ontario, Canada Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
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134
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Gilon P, Chae HY, Rutter GA, Ravier MA. Calcium signaling in pancreatic β-cells in health and in Type 2 diabetes. Cell Calcium 2014; 56:340-61. [DOI: 10.1016/j.ceca.2014.09.001] [Citation(s) in RCA: 116] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 08/26/2014] [Accepted: 09/01/2014] [Indexed: 12/24/2022]
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135
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Affiliation(s)
- Guy A Rutter
- Section of Cell Biology, Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, Imperial College London, Hammersmith Hospital, London, U.K
| | - Paolo Pinton
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies, University of Ferrara, Ferrara, Italy
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136
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Mizukami H, Takahashi K, Inaba W, Tsuboi K, Osonoi S, Yoshida T, Yagihashi S. Involvement of oxidative stress-induced DNA damage, endoplasmic reticulum stress, and autophagy deficits in the decline of β-cell mass in Japanese type 2 diabetic patients. Diabetes Care 2014; 37:1966-74. [PMID: 24705612 DOI: 10.2337/dc13-2018] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Deficits of β-cells characterize the islet pathology in type 2 diabetes. It is yet to be clear how the β-cell loss develops in type 2 diabetes. We explored the implication of oxidative stress, endoplasmic reticulum (ER)-induced stress, and autophagy deficit in the β-cell decline in Japanese type 2 diabetic patients. RESEARCH DESIGN AND METHODS Pancreases from recent autopsy cases of 47 type 2 diabetic and 30 nondiabetic subjects were investigated on the islet structure with morphometric analysis. Volume densities of islet (Vi), β-cell (Vβ), and α-cell (Vα) were measured. To evaluate cell damage of endocrine cells, immunohistochemical expressions of oxidative stress-related DNA damage as expressed by γH2AX, ER stress-related cell damage as CCAAT/enhancer 1 binding protein-β (C/EBP-β), and autophagy deficit as P62 were semiquantified, and their correlations to islet changes were sought. RESULTS Compared with nondiabetic subjects, Vβ was reduced in diabetic subjects. Contrariwise, there was an increase in Vα. There was a significant link between reduced Vβ and increased HbA1c levels (P < 0.01) and a trend of inverse correlation between Vβ and duration of diabetes (P = 0.06). Expressions of γH2AX, P62, and C/EBP-β were all enhanced in diabetic islets, and reduced Vβ correlated with the intensity of γH2AX expression but not with C/EBP-β or P62 expressions. Combined expressions of γH2AX, P62, and C/EBP-β were associated with severe reduction of Vβ. CONCLUSIONS β-Cell deficit in type 2 diabetes was associated with increased oxidative stress and may further be augmented by autophagic deficits and ER stress.
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Affiliation(s)
- Hiroki Mizukami
- Department of Pathology and Molecular Medicine, Hirosaki University Graduate School of Medicine, Hirosaki, Japan
| | - Kazunori Takahashi
- Department of Pathology and Molecular Medicine, Hirosaki University Graduate School of Medicine, Hirosaki, Japan
| | - Wataru Inaba
- Department of Pathology and Molecular Medicine, Hirosaki University Graduate School of Medicine, Hirosaki, Japan
| | - Kentaro Tsuboi
- Department of Pathology and Molecular Medicine, Hirosaki University Graduate School of Medicine, Hirosaki, Japan
| | - Sho Osonoi
- Department of Pathology and Molecular Medicine, Hirosaki University Graduate School of Medicine, Hirosaki, Japan
| | - Taro Yoshida
- Department of Pathology and Molecular Medicine, Hirosaki University Graduate School of Medicine, Hirosaki, Japan
| | - Soroku Yagihashi
- Department of Pathology and Molecular Medicine, Hirosaki University Graduate School of Medicine, Hirosaki, Japan
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Abstract
The failure of pancreatic β‐cells to supply insulin in quantities sufficient to maintain euglycemia is a hallmark of type 2 diabetes. Perturbation of β‐cell cholesterol homeostasis, culminating in elevated intracellular cholesterol levels, impairs insulin secretion and has therefore been proposed as a mechanism contributing to β‐cell dysfunction. The manner in which this occurs, however, is unclear. Cholesterol is an essential lipid, as well as a major component of membrane rafts, and numerous proteins critical for the regulation of insulin secretion have been reported to associate with these domains. Although this suggests that alterations in membrane rafts could partially account for the reduction in insulin secretion observed when β‐cell cholesterol accumulates, this has not yet been demonstrated. In this review, we provide a brief overview of recent work implicating membrane rafts in some of the basic molecular mechanisms of insulin secretion, and discuss the insight it provides into the β‐cell dysfunction characteristic of type 2 diabetes. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2012.00200.x, 2012)
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Affiliation(s)
- Ronald Dirkx
- Molecular Diabetology, Paul Langerhans Institute Dresden, School of Medicine and University Clinic "Carl Gustav Carus", Dresden University of Technology
| | - Michele Solimena
- Molecular Diabetology, Paul Langerhans Institute Dresden, School of Medicine and University Clinic "Carl Gustav Carus", Dresden University of Technology ; Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
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Morita S, Sakagashira S, Ueyama M, Shimajiri Y, Furuta M, Sanke T. Progressive deterioration of insulin secretion in Japanese type 2 diabetic patients in comparison with those who carry the S20G mutation of the islet amyloid polypeptide gene: A long-term follow-up study. J Diabetes Investig 2014; 2:287-92. [PMID: 24843500 PMCID: PMC4014969 DOI: 10.1111/j.2040-1124.2011.00102.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
UNLABELLED Aims/Introduction: In order to clarify the enhanced β-cell dysfunction in type 2 diabetic patients carrying the S20G mutation of the islet amyloid polypeptide gene (S20G-patients), we first estimated the decline of insulin secretion in Japanese type 2 diabetic patients without the S20G mutation (non-S20G-T2D-patients) by long-term observation, and then compared it with that of the S20G-patients. MATERIALS AND METHODS We followed 70 non-S20G-T2D-patients (body mass index <30 kg/m(2)) for more than 10 years and six S20G-patients for more than 5 years. We measured fasting C-peptide (F-CP) every 1-2 years and carried out a glucagon test at least once during the follow-up period. F-CP and a 5-min value of C-peptide after glucagon injection (5'-CP) were used as the indices of insulin secretion. We excluded patients who had renal dysfunction and/or anti-insulin antibodies in the insulin-treated patients. The individual annual declines were calculated from the slopes of the regression lines between C-peptide levels and duration (years after diagnosis). RESULTS The mean individual annual declines of both F-CP and 5'-CP were significantly greater in the S20G-patients than the non-S20G-T2D-patients (F-CP; 0.047 ± 0.026 vs 0.011 ± 0.037 nmol/L/year, P = 0.025, 5'-CP; 0.139 ± 0.055 vs 0.022 ± 0.012 nmol/L/year, P = 0.008). CONCLUSIONS We established the annual decline of insulin secretion in the Japanese type 2 diabetic patients by the long-term observation. The results show that the decline of insulin secretion is more rapid in the S20G-patients than the non-S20G-T2D-patients. (J Diabetes Invest, doi: 10.1111/j.2040-1124.2011.00102.x, 2011).
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Affiliation(s)
- Shuhei Morita
- Department of Clinical Laboratory Medicine, Wakayama Medical University, Wakayama, Japan
| | - Setsuya Sakagashira
- Department of Clinical Laboratory Medicine, Wakayama Medical University, Wakayama, Japan
| | - Minoru Ueyama
- Department of Clinical Laboratory Medicine, Wakayama Medical University, Wakayama, Japan
| | - Yoshinori Shimajiri
- Department of Clinical Laboratory Medicine, Wakayama Medical University, Wakayama, Japan
| | - Machi Furuta
- Department of Clinical Laboratory Medicine, Wakayama Medical University, Wakayama, Japan
| | - Tokio Sanke
- Department of Clinical Laboratory Medicine, Wakayama Medical University, Wakayama, Japan
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139
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Stahnke MJ, Dickel C, Schröder S, Kaiser D, Blume R, Stein R, Pouponnot C, Oetjen E. Inhibition of human insulin gene transcription and MafA transcriptional activity by the dual leucine zipper kinase. Cell Signal 2014; 26:1792-9. [PMID: 24726898 DOI: 10.1016/j.cellsig.2014.04.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 04/01/2014] [Accepted: 04/04/2014] [Indexed: 01/25/2023]
Abstract
Insulin biosynthesis is an essential β-cell function and inappropriate insulin secretion and biosynthesis contribute to the pathogenesis of diabetes mellitus type 2. Previous studies showed that the dual leucine zipper kinase (DLK) induces β-cell apoptosis. Since β-cell dysfunction precedes β-cell loss, in the present study the effect of DLK on insulin gene transcription was investigated in the HIT-T15 β-cell line. Downregulation of endogenous DLK increased whereas overexpression of DLK decreased human insulin gene transcription. 5'- and 3'-deletion human insulin promoter analyses resulted in the identification of a DLK responsive element that mapped to the DNA binding-site for the β-cell specific transcription factor MafA. Overexpression of DLK wild-type but not its kinase-dead mutant inhibited MafA transcriptional activity conferred by its transactivation domain. Furthermore, in the non-β-cell line JEG DLK inhibited MafA overexpression-induced human insulin promoter activity. Overexpression of MafA and DLK or its kinase-dead mutant into JEG cells revealed that DLK but not its mutant reduced MafA protein content. Inhibition of the down-stream DLK kinase c-Jun N-terminal kinase (JNK) by SP600125 attenuated DLK-induced MafA loss. Furthermore, mutation of the serine 65 to alanine, shown to confer MafA protein stability, increased MafA-dependent insulin gene transcription and prevented DLK-induced MafA loss in JEG cells. These data suggest that DLK by activating JNK triggers the phosphorylation and degradation of MafA thereby attenuating insulin gene transcription. Given the importance of MafA for β-cell function, the inhibition of DLK might preserve β-cell function and ultimately retard the development of diabetes mellitus type 2.
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Affiliation(s)
| | - Corinna Dickel
- Department of Pharmacology, University Medical Center Göttingen, Göttingen, Germany
| | - Sabine Schröder
- Institute of Clinical Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Diana Kaiser
- Institute of Clinical Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Roland Blume
- Department of Pharmacology, University Medical Center Göttingen, Göttingen, Germany
| | - Roland Stein
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Celio Pouponnot
- Institut Curie, CNRS UMR 3347, INSERM U1021, Paris Sud University Centre de Recherche, Orsay, France
| | - Elke Oetjen
- Department of Pharmacology, University Medical Center Göttingen, Göttingen, Germany; Institute of Clinical Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; DZHK (German Centre for Cardiovascular Research) partner site Hamburg/Kiel/Lübeck, Hamburg, Germany; Institute of Pharmacy, University of Hamburg, Hamburg, Germany.
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140
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Li H, Wei S, Cheng K, Gounko NV, Ericksen RE, Xu A, Hong W, Han W. BIG3 inhibits insulin granule biogenesis and insulin secretion. EMBO Rep 2014; 15:714-22. [PMID: 24711543 DOI: 10.1002/embr.201338181] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
While molecular regulation of insulin granule exocytosis is relatively well understood, insulin granule biogenesis and maturation and its influence on glucose homeostasis are relatively unclear. Here, we identify a novel protein highly expressed in insulin-secreting cells and name it BIG3 due to its similarity to BIG/GBF of the Arf-GTP exchange factor (GEF) family. BIG3 is predominantly localized to insulin- and clathrin-positive trans-Golgi network (TGN) compartments. BIG3-deficient insulin-secreting cells display increased insulin content and granule number and elevated insulin secretion upon stimulation. Moreover, BIG3 deficiency results in faster processing of proinsulin to insulin and chromogranin A to β-granin in β-cells. BIG3-knockout mice exhibit postprandial hyperinsulinemia, hyperglycemia, impaired glucose tolerance, and insulin resistance. Collectively, these results demonstrate that BIG3 negatively modulates insulin granule biogenesis and insulin secretion and participates in the regulation of systemic glucose homeostasis.
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Affiliation(s)
- Hongyu Li
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore Singapore Bioimaging Consortium, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Shunhui Wei
- Singapore Bioimaging Consortium, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Kenneth Cheng
- State Key Laboratory of Pharmaceutical Biotechnology, University of Hong Kong, Hong Kong, China Department of Medicine, University of Hong Kong, Hong Kong, China
| | - Natalia V Gounko
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore Joint IMB-IMCB Electron Microscopy Suite, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Russell E Ericksen
- Singapore Bioimaging Consortium, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Aimin Xu
- State Key Laboratory of Pharmaceutical Biotechnology, University of Hong Kong, Hong Kong, China Department of Medicine, University of Hong Kong, Hong Kong, China Pharmacology and Pharmacy, University of Hong Kong, Hong Kong, China
| | - Wanjin Hong
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Weiping Han
- Singapore Bioimaging Consortium, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
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Westwell-Roper C, Ehses JA. Is there a role for the adaptive immune system in pancreatic beta cell failure in type 2 diabetes? Diabetologia 2014; 57:447-50. [PMID: 24362729 DOI: 10.1007/s00125-013-3151-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Accepted: 12/04/2013] [Indexed: 01/23/2023]
Abstract
Pancreatic beta cell failure dictates the clinical onset of type 2 diabetes, with insulin secretion insufficient to overcome peripheral tissue insulin resistance. Over the past 5-10 years, a convincing case has emerged supporting the contribution of islet inflammation to this beta cell failure. IL-1 is central to this insult, impairing insulin secretion in preclinical and clinical studies. Further, islet-infiltrating macrophages are a major source of IL-1 and other cytokines in response to elevated levels of nutrients (glucose, saturated fatty acids), endocannabinoids and islet amyloid polypeptide (IAPP). In this issue of Diabetologia, Butcher et al have further characterised immune cell subsets present in islets from individuals with type 2 diabetes (DOI: 10.1007/s00125-013-3116-5). Increased numbers of CD45(+) leucocytes were found in these islets compared with islets from healthy controls, with an elevated proportion of CD20(+) B cells within the CD45(+) population. Their data also suggest that absolute numbers of CD3(+) T cells and CD11b(+)CD11c(+) myeloid cells may be increased in islets from individuals with type 2 diabetes. While many aspects of islet inflammation await further exploration, the study from Butcher and colleagues suggests a role for immune cell-mediated inflammation early in disease pathogenesis, and supports the concept that targeting the immune system may slow continued beta cell demise in type 2 diabetes.
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Affiliation(s)
- Clara Westwell-Roper
- Department of Pathology and Laboratory Medicine, Faculty of Medicine, Child & Family Research Institute, University of British Columbia, Vancouver, BC, Canada
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Butcher MJ, Hallinger D, Garcia E, Machida Y, Chakrabarti S, Nadler J, Galkina EV, Imai Y. Association of proinflammatory cytokines and islet resident leucocytes with islet dysfunction in type 2 diabetes. Diabetologia 2014; 57:491-501. [PMID: 24429578 PMCID: PMC3966210 DOI: 10.1007/s00125-013-3116-5] [Citation(s) in RCA: 117] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 11/01/2013] [Indexed: 12/23/2022]
Abstract
AIMS/HYPOTHESIS Chronic inflammation in type 2 diabetes is proposed to affect islets as well as insulin target organs. However, the nature of islet inflammation and its effects on islet function in type 2 diabetes remain unclear. Moreover, the immune cell profiles of human islets in healthy and type 2 diabetic conditions are undefined. We aimed to investigate the correlation between proinflammatory cytokine expression, islet leucocyte composition and insulin secretion in type 2 diabetic human islets. METHODS Human islets from organ donors with or without type 2 diabetes were studied. First and second phases of glucose-stimulated insulin secretion were determined by perifusion. The expression of inflammatory markers was obtained by quantitative PCR. Immune cells within human islets were analysed by FACS. RESULTS Type 2 diabetic islets, especially those without first-phase insulin secretion, displayed higher CCL2 and TNFa expression than healthy islets. CD45(+) leucocytes were elevated in type 2 diabetic islets, to a greater extent in moderately functional type 2 diabetic islets compared with poorly functional ones, and corresponded with elevated ALOX12 but not with CCL2 or TNFa expression. T and B lymphocytes and CD11c(+) cells were detectable within both non-diabetic and type 2 diabetic islet leucocytes. Importantly, the proportion of B cells was significantly elevated within type 2 diabetic islets. CONCLUSIONS/INTERPRETATION Elevated total islet leucocyte content and proinflammatory mediators correlated with islet dysfunction, suggesting that heterogeneous insulitis occurs during the development of islet dysfunction in type 2 diabetes. In addition, the altered B cell content highlights a potential role for the adaptive immune response in islet dysfunction.
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Affiliation(s)
- Matthew J. Butcher
- Department of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, 700 West Olney Road, Norfolk, VA 23507-1696, USA
| | - Daniel Hallinger
- Department of Internal Medicine, Strelitz Diabetes Center, Eastern Virginia Medical School, 700 West Olney Road, Norfolk, VA 23507-1696, USA
| | - Eden Garcia
- Department of Internal Medicine, Strelitz Diabetes Center, Eastern Virginia Medical School, 700 West Olney Road, Norfolk, VA 23507-1696, USA
| | - Yui Machida
- Department of Internal Medicine, Strelitz Diabetes Center, Eastern Virginia Medical School, 700 West Olney Road, Norfolk, VA 23507-1696, USA
| | - Swarup Chakrabarti
- Department of Internal Medicine, Strelitz Diabetes Center, Eastern Virginia Medical School, 700 West Olney Road, Norfolk, VA 23507-1696, USA
| | - Jerry Nadler
- Department of Internal Medicine, Strelitz Diabetes Center, Eastern Virginia Medical School, 700 West Olney Road, Norfolk, VA 23507-1696, USA
| | - Elena V. Galkina
- Department of Microbiology and Molecular Cell Biology, Eastern Virginia Medical School, 700 West Olney Road, Norfolk, VA 23507-1696, USA
| | - Yumi Imai
- Department of Internal Medicine, Strelitz Diabetes Center, Eastern Virginia Medical School, 700 West Olney Road, Norfolk, VA 23507-1696, USA
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Utzschneider KM, Largajolli A, Bertoldo A, Marcovina S, Nelson JE, Yeh MM, Kowdley KV, Kahn SE. Serum ferritin is associated with non-alcoholic fatty liver disease and decreased Β-cell function in non-diabetic men and women. J Diabetes Complications 2014; 28:177-84. [PMID: 24360972 PMCID: PMC3943487 DOI: 10.1016/j.jdiacomp.2013.11.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Revised: 11/15/2013] [Accepted: 11/18/2013] [Indexed: 02/08/2023]
Abstract
AIMS We sought to determine whether NAFLD is associated with poorer β-cell function and if any β-cell dysfunction is associated with abnormal markers of iron or inflammation. METHODS This was a cross-sectional study of 15 non-diabetic adults with NAFLD and 15 non-diabetic age and BMI-matched controls. Insulin sensitivity was measured by isotope-labeled hyperinsulinemic-euglycemic clamps and β-cell function by both oral (OGTT) and intravenous glucose tolerance tests. Liver and abdominal fat composition was evaluated by CT scan. Fasting serum levels of ferritin, transferrin-iron saturation, IL-6, TNFα and hsCRP were measured. RESULTS Compared to controls, subjects with NAFLD had lower hepatic and systemic insulin sensitivity and β-cell function was decreased as measured by the oral disposition index. Fasting serum ferritin and transferrin-iron saturation were higher in NAFLD and were positively associated with liver fat. Serum ferritin was negatively associated with β-cell function measured by both oral and intravenous tests, but was not associated with insulin sensitivity. IL-6, TNFα and hsCRP did not differ between groups and did not correlate with serum ferritin, liver fat or measures of β-cell function. CONCLUSIONS These findings support a potential pathophysiological link between iron metabolism, liver fat and diabetes risk.
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Affiliation(s)
- Kristina M Utzschneider
- VA Puget Sound Health Care System, Department of Medicine, Division of Endocrinology and Metabolism, Seattle, WA; University of Washington, Department of Medicine, Division of Metabolism, Endocrinology and Nutrition, Seattle, WA.
| | | | | | - Santica Marcovina
- Department of Medicine, University of Washington and the Northwest Lipid Metabolism and Diabetes Research Laboratory, Seattle, WA
| | - James E Nelson
- Digestive Disease Institute, Virginia Mason Medical Center and Benaroya Research Institute, Seattle, WA
| | - Matthew M Yeh
- University of Washington, Department of Pathology, Seattle, WA
| | - Kris V Kowdley
- Digestive Disease Institute, Virginia Mason Medical Center and Benaroya Research Institute, Seattle, WA; University of Washington, Department of Medicine, Division of Gastroenterology/Hepatology, Seattle, WA
| | - Steven E Kahn
- VA Puget Sound Health Care System, Department of Medicine, Division of Endocrinology and Metabolism, Seattle, WA; University of Washington, Department of Medicine, Division of Metabolism, Endocrinology and Nutrition, Seattle, WA
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Toll-like receptors and NLRP3 as central regulators of pancreatic islet inflammation in type 2 diabetes. Immunol Cell Biol 2014; 92:314-23. [PMID: 24492799 DOI: 10.1038/icb.2014.4] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Revised: 01/03/2014] [Accepted: 01/06/2014] [Indexed: 12/17/2022]
Abstract
The global health and economic burden of type 2 diabetes (T2D) has reached staggering proportions. Current projections estimate that 592 million people will have diabetes by 2035. T2D-which comprises 90% of cases-is a complex disease, in most cases resulting from a combination of predisposing genes and an unhealthy environment. Clinical onset of the disease occurs when pancreatic β cells fail in the face of insulin resistance. It has long been appreciated that chronic activation of the innate immune system is associated with T2D, and many organs critical to the regulation of glucose homeostasis show signs of a chronic inflammatory process, including the pancreatic islets of Langerhans. Recent clinical trials using IL-1-targeting agents have confirmed that inflammation contributes to β-cell failure in humans with T2D. However, little is known about the nature of the pro-inflammatory response within the islet, and there is considerable debate about the triggers for islet inflammation, which may be systemically derived and/or tissue-specific. In this review, we present evidence that Toll-like receptors 2 and 4 and the NLRP3 (Nucleotide-binding oligomerization domain, Leucine-rich Repeat and Pyrin domain containing 3) inflammasome are triggers for islet inflammation in T2D and propose that the activation of macrophages by these triggers mediates islet endocrine cell dysfunction. Therapeutically targeting these receptors may improve hyperglycemia and protect the β cell in T2D.
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145
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Potter KJ, Westwell-Roper CY, Klimek-Abercrombie AM, Warnock GL, Verchere CB. Death and dysfunction of transplanted β-cells: lessons learned from type 2 diabetes? Diabetes 2014; 63:12-9. [PMID: 24357689 DOI: 10.2337/db12-0364] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
β-Cell replacement by islet transplantation is a potential curative therapy for type 1 diabetes. Despite advancements in islet procurement and immune suppression that have increased islet transplant survival, graft function progressively declines, and many recipients return to insulin dependence within a few years posttransplant. The progressive loss of β-cell function in islet transplants seems unlikely to be explained by allo- and autoimmune-mediated mechanisms alone and in a number of ways resembles β-cell failure in type 2 diabetes. That is, both following transplantation and in type 2 diabetes, islets exhibit decreased first-phase glucose-stimulated insulin secretion, impaired proinsulin processing, inflammation, formation of islet amyloid, signs of oxidative and endoplasmic reticulum stress, and β-cell death. These similarities suggest common mechanisms may underlie loss of insulin production in both type 2 diabetes and islet transplantation and point to the potential for therapeutic approaches used in type 2 diabetes that target the β-cell, such as incretin-based therapies, as adjuncts for immunosuppression in islet transplantation.
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Affiliation(s)
- Kathryn J Potter
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
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146
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Kramer CK, Choi H, Zinman B, Retnakaran R. Determinants of reversibility of β-cell dysfunction in response to short-term intensive insulin therapy in patients with early type 2 diabetes. Am J Physiol Endocrinol Metab 2013; 305:E1398-407. [PMID: 24129396 DOI: 10.1152/ajpendo.00447.2013] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Short-term intensive insulin therapy (IIT) can improve pancreatic β-cell function when administered early in the course of type 2 diabetes mellitus (T2DM). However, the degree of improvement in response to this therapy varies between patients. Thus, we sought to characterize the determinants of improvement in β-cell function in response to short-term IIT in early T2DM. Sixty-three patients with mean 3.0 ± 2.1 yr duration of T2DM and Hb A1c of 6.8 ± 0.8% underwent 4 wk of IIT consisting of basal insulin detemir and premeal insulin aspart, with oral glucose tolerance test administered at baseline and 1 day post-IIT. β-Cell function before and after IIT was assessed by Insulin Secretion Sensitivity Index-2 (ISSI-2). Reversibility of β-cell dysfunction was defined as percentage change in ISSI-2 of ≥25%. Overall, the study population experienced an increase in ISSI-2 from baseline to post-IIT (P = 0.01), with one-third of participants achieving ≥25% improvement in ISSI-2. Compared with their peers, those with increases in ISSI-2 of ≥25% had greater decrements in fasting glucose (P < 0.0001), Hb A1c (P = 0.001), ALT (P = 0.04), AST (P = 0.02), and HOMA-IR (P < 0.0001). On logistical regression analysis, baseline Hb A1c (OR = 2.83, 95% CI 1.16-6.88, P = 0.02) and change in HOMA-IR (OR = 0.008, 95%CI 0.0004-0.16, P = 0.001) emerged as independent predictors of reversibility of β-cell dysfunction. Indeed, reversibility of β-cell dysfunction was achieved in only those participants in whom IIT yielded an improvement in HOMA-IR. In conclusion, decline in HOMA-IR may be a key determinant of improvement of β-cell function in response to short-term IIT, suggesting a fundamental contribution of insulin resistance to the reversible component of β-cell dysfunction in early T2DM.
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147
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ER stress in rodent islets of Langerhans is concomitant with obesity and β-cell compensation but not with β-cell dysfunction and diabetes. Nutr Diabetes 2013; 3:e93. [PMID: 24145577 PMCID: PMC3817349 DOI: 10.1038/nutd.2013.35] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Revised: 08/15/2013] [Accepted: 09/06/2013] [Indexed: 12/20/2022] Open
Abstract
Objective: The objective of this study was to determine whether ER stress correlates with β-cell dysfunction in obesity-associated diabetes. Methods: Quantitative RT-PCR and western blot analysis were used to investigate changes in the expression of markers of ER stress, the unfolded protein response (UPR) and β-cell function in islets isolated from (1) non-diabetic Zucker obese (ZO) and obese female Zucker diabetic fatty (fZDF) rats compared with their lean littermates and from (2) high-fat-diet-fed fZDF rats (HF-fZDF), to induce diabetes, compared with age-matched non-diabetic obese fZDF rats. Results: Markers of an adaptive ER stress/UPR and β-cell function are elevated in islets isolated from ZO and fZDF rats compared with their lean littermates. In islets isolated from HF-fZDF rats, there was no significant change in the expression of markers of ER stress compared with age matched, obese, non-diabetic fZDF rats. Conclusions: These results provide evidence that obesity-induced activation of the UPR is an adaptive response for increasing the ER folding capacity to meet the increased demand for insulin. As ER stress is not exacerbated in high-fat-diet-induced diabetes, we suggest that failure of the islet to mount an effective adaptive UPR in response to an additional increase in insulin demand, rather than chronic ER stress, may ultimately lead to β-cell failure and hence diabetes.
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148
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Kramer CK, Zinman B, Retnakaran R. Short-term intensive insulin therapy in type 2 diabetes mellitus: a systematic review and meta-analysis. Lancet Diabetes Endocrinol 2013; 1:28-34. [PMID: 24622264 DOI: 10.1016/s2213-8587(13)70006-8] [Citation(s) in RCA: 152] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
BACKGROUND Studies have shown that, when implemented early in the course of type 2 diabetes mellitus, treatment with intensive insulin therapy for 2-3 weeks can induce a glycaemic remission, wherein patients are able to maintain normoglycaemia without any anti-diabetic medication. We thus did a systematic review and meta-analysis of interventional studies to assess the effect of short-term intensive insulin therapy on the pathophysiological defects underlying type 2 diabetes mellitus (pancreatic β-cell dysfunction and insulin resistance) and identify clinical predictors of remission. METHODS We identified studies published between 1950 and Nov 19, 2012, which assessed the effect of intensive insulin therapy on β-cell function or insulin resistance, or both, or assessed long-term drug-free glycaemic remission in adults aged 18 years or older with newly diagnosed type 2 diabetes mellitus. We calculated pooled estimates by random-effects model. This study is registered with International Prospective Register of Systematic Reviews, number CRD42012002829. FINDINGS We identified 1645 studies of which seven fulfilled inclusion criteria (n=839 participants). Five studies were non-randomised. A pooled analysis of the seven studies showed a post-intensive insulin therapy increase in Homeostasis Model Assessment of β-cell function as compared with baseline (1·13, 95% CI 1·02 to 1·25) and a decrease in Homeostasis Model Assessment of Insulin Resistance (-0·57, -0·84 to -0·29). In the four studies that assessed glycaemic remission (n=559 participants), the proportion of participants in drug-free remission was about 66·2% (292 of 441 patients) after 3 months of follow-up, about 58·9% (222 of 377 patients) after 6 months, about 46·3% (229 of 495 patients) after 12 months, and about 42·1% (53 of 126 patients) after 24 months. Patients who achieved remission had higher body-mass index than those who did not achieve remission (1·06 kg/m(2), 95% CI 0·55 to 1·58) and lower fasting plasma glucose (-0·59 mmol/L, 95% CI -1·11 to -0·07) at baseline. INTERPRETATION Short-term intensive insulin therapy can improve the underlying pathophysiology in early type 2 diabetes mellitus, and thus might provide a treatment strategy for modifying the natural history of diabetes. FUNDING None.
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Affiliation(s)
- Caroline Kaercher Kramer
- Leadership Sinai Centre for Diabetes, Mount Sinai Hospital, Toronto, ON, Canada; Division of Endocrinology, University of Toronto, Toronto, ON, Canada
| | - Bernard Zinman
- Leadership Sinai Centre for Diabetes, Mount Sinai Hospital, Toronto, ON, Canada; Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, ON, Canada; Division of Endocrinology, University of Toronto, Toronto, ON, Canada
| | - Ravi Retnakaran
- Leadership Sinai Centre for Diabetes, Mount Sinai Hospital, Toronto, ON, Canada; Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, ON, Canada; Division of Endocrinology, University of Toronto, Toronto, ON, Canada.
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149
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Aston-Mourney K, Subramanian SL, Zraika S, Samarasekera T, Meier DT, Goldstein LC, Hull RL. One year of sitagliptin treatment protects against islet amyloid-associated β-cell loss and does not induce pancreatitis or pancreatic neoplasia in mice. Am J Physiol Endocrinol Metab 2013; 305:E475-84. [PMID: 23736544 PMCID: PMC3891222 DOI: 10.1152/ajpendo.00025.2013] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The dipeptidyl peptidase-4 (DPP-4) inhibitor sitagliptin is an attractive therapy for diabetes, as it increases insulin release and may preserve β-cell mass. However, sitagliptin also increases β-cell release of human islet amyloid polypeptide (hIAPP), the peptide component of islet amyloid, which is cosecreted with insulin. Thus, sitagliptin treatment may promote islet amyloid formation and its associated β-cell toxicity. Conversely, metformin treatment decreases islet amyloid formation by decreasing β-cell secretory demand and could therefore offset sitagliptin's potential proamyloidogenic effects. Sitagliptin treatment has also been reported to be detrimental to the exocrine pancreas. We investigated whether long-term sitagliptin treatment, alone or with metformin, increased islet amyloid deposition and β-cell toxicity and induced pancreatic ductal proliferation, pancreatitis, and/or pancreatic metaplasia/neoplasia. hIAPP transgenic and nontransgenic littermates were followed for 1 yr on no treatment, sitagliptin, metformin, or the combination. Islet amyloid deposition, β-cell mass, insulin release, and measures of exocrine pancreas pathology were determined. Relative to untreated mice, sitagliptin treatment did not increase amyloid deposition, despite increasing hIAPP release, and prevented amyloid-induced β-cell loss. Metformin treatment alone or with sitagliptin decreased islet amyloid deposition to a similar extent vs untreated mice. Ductal proliferation was not altered among treatment groups, and no evidence of pancreatitis, ductal metaplasia, or neoplasia were observed. Therefore, long-term sitagliptin treatment stimulates β-cell secretion without increasing amyloid formation and protects against amyloid-induced β-cell loss. This suggests a novel effect of sitagliptin to protect the β-cell in type 2 diabetes that appears to occur without adverse effects on the exocrine pancreas.
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Affiliation(s)
- Kathryn Aston-Mourney
- Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, Veterans Affairs Puget Sound Health Care System and University of Washington, Seattle, Washington
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150
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Meier JJ, Bonadonna RC. Role of reduced β-cell mass versus impaired β-cell function in the pathogenesis of type 2 diabetes. Diabetes Care 2013; 36 Suppl 2:S113-9. [PMID: 23882035 PMCID: PMC3920783 DOI: 10.2337/dcs13-2008] [Citation(s) in RCA: 170] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Juris J Meier
- Division of Diabetology and Gastrointestinal Endocrinology, St. Josef-Hospital, Ruhr-University of Bochum, Bochum, Germany.
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