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Zeng W, Cai N, Liu J, Liu K, Lin S, Zeng L. Caveolin-1 deficiency alleviates palmitate-induced intracellular lipid accumulation and inflammation in pancreatic β cells. J Physiol Biochem 2024; 80:175-188. [PMID: 38032518 DOI: 10.1007/s13105-023-00995-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 10/31/2023] [Indexed: 12/01/2023]
Abstract
Lipotoxicity-induced pancreatic β cell damage is a strong predictor of type 2 diabetes mellitus (T2DM). Our previous work showed that Caveolin-1 (Cav-1) depletion decreased β-cell apoptosis and improved β-cell viability. Further microarray analysis indicated significant changes in the expression of genes related to fatty acid metabolism and inflammation. The objective of this study was to explore the role of Cav-1 in intracellular lipid accumulation and inflammation in β cells under lipotoxic conditions. Here, we established a β-cell-specific Cav-1 knockout (β-Cav-1 KO) mouse model and a CAV-1 depleted β cell line (NIT-1). We found that Cav-1 silencing significantly reduced palmitate (PA)-induced intracellular triglyceride (TG) accumulation and decreased proinflammatory factor expression in both the mouse and cell models. Further mechanistic investigation revealed that amelioration of lipid metabolism was achieved through the downregulation of lipogenic markers (SREBP-1c, FAS and ACC) and upregulation of a fatty acid oxidation marker (CPT-1). Meanwhile, decrease of inflammatory cytokines (IL-6, TNF-α, and IL-1β) secretion was found with the involvement of the IKKβ/NF-κB signaling pathways. Our findings suggest that Cav-1 is of considerable importance in regulating lipotoxicity-induced β-cell intracellular lipid accumulation and inflammation.
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Affiliation(s)
- Wen Zeng
- Department of Endocrinology and Metabolism, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, 510630, Guangdong, China
- Guangdong Provincial Key Laboratory of Diabetology, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, 510630, Guangdong, China
- Guangzhou Municipal Key Laboratory of Mechanistic and Translational Obesity Research, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, 510630, Guangdong, China
- Medical Center for Comprehensive Weight Control, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, 510630, Guangdong, China
| | - Nan Cai
- Department of Endocrinology and Metabolism, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, 510630, Guangdong, China
- Guangdong Provincial Key Laboratory of Diabetology, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, 510630, Guangdong, China
- Guangzhou Municipal Key Laboratory of Mechanistic and Translational Obesity Research, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, 510630, Guangdong, China
- Medical Center for Comprehensive Weight Control, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, 510630, Guangdong, China
| | - Jia Liu
- Department of Endocrinology and Metabolism, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, 510630, Guangdong, China
- Guangzhou Municipal Key Laboratory of Mechanistic and Translational Obesity Research, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, 510630, Guangdong, China
- Medical Center for Comprehensive Weight Control, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, 510630, Guangdong, China
| | - Kunying Liu
- Department of Endocrinology and Metabolism, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, 510630, Guangdong, China
- Guangdong Provincial Key Laboratory of Diabetology, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, 510630, Guangdong, China
| | - Shuo Lin
- Department of Endocrinology and Metabolism, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, 510630, Guangdong, China.
- Guangdong Provincial Key Laboratory of Diabetology, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, 510630, Guangdong, China.
- Guangzhou Municipal Key Laboratory of Mechanistic and Translational Obesity Research, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, 510630, Guangdong, China.
- Medical Center for Comprehensive Weight Control, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, 510630, Guangdong, China.
| | - Longyi Zeng
- Department of Endocrinology and Metabolism, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, 510630, Guangdong, China.
- Guangdong Provincial Key Laboratory of Diabetology, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, 510630, Guangdong, China.
- Guangzhou Municipal Key Laboratory of Mechanistic and Translational Obesity Research, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, 510630, Guangdong, China.
- Medical Center for Comprehensive Weight Control, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, 510630, Guangdong, China.
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Wang Y, Wang J, Tao SY, Liang Z, Xie R, Liu NN, Deng R, Zhang Y, Deng D, Jiang G. Mitochondrial damage-associated molecular patterns: A new insight into metabolic inflammation in type 2 diabetes mellitus. Diabetes Metab Res Rev 2024; 40:e3733. [PMID: 37823338 DOI: 10.1002/dmrr.3733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 07/18/2023] [Accepted: 09/08/2023] [Indexed: 10/13/2023]
Abstract
The pathogenesis of diabetes is accompanied by increased levels of inflammatory factors, also known as "metabolic inflammation", which runs through the whole process of the occurrence and development of the disease. Mitochondria, as the key site of glucose and lipid metabolism, is often accompanied by mitochondrial function damage in type 2 diabetes mellitus (T2DM). Damaged mitochondria release pro-inflammatory factors through damage-related molecular patterns that activate inflammation pathways and reactions to oxidative stress, further aggravate metabolic disorders, and form a vicious circle. Currently, the pathogenesis of diabetes is still unclear, and clinical treatment focuses primarily on symptomatic intervention of the internal environment of disorders of glucose and lipid metabolism with limited clinical efficacy. The proinflammatory effect of mitochondrial damage-associated molecular pattern (mtDAMP) in T2DM provides a new research direction for exploring the pathogenesis and intervention targets of T2DM. Therefore, this review covers the most recent findings on the molecular mechanism and related signalling cascades of inflammation caused by mtDAMP in T2DM and discusses its pathogenic role of it in the pathological process of T2DM to search potential intervention targets.
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Affiliation(s)
- Yan Wang
- School of Traditional Chinese Medicine, Beijing University of Chinese Medicine, Beijing, China
- Shandong University of Traditional Chinese Medicine, Jinan, Shandong, China
| | - Jingwu Wang
- Shandong University of Traditional Chinese Medicine, Jinan, Shandong, China
| | - Si-Yu Tao
- School of Traditional Chinese Medicine, Beijing University of Chinese Medicine, Beijing, China
| | | | - Rong Xie
- Xinjiang Medical University, Urumqi, China
| | - Nan-Nan Liu
- School of Traditional Chinese Medicine, Beijing University of Chinese Medicine, Beijing, China
| | - Ruxue Deng
- School of Traditional Chinese Medicine, Beijing University of Chinese Medicine, Beijing, China
| | - Yuelin Zhang
- School of Traditional Chinese Medicine, Beijing University of Chinese Medicine, Beijing, China
| | - Deqiang Deng
- Department of Endocrinology, Urumqi Hospital of Traditional Chinese Medicine, Urumqi, China
| | - Guangjian Jiang
- School of Traditional Chinese Medicine, Beijing University of Chinese Medicine, Beijing, China
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Sphingosine-1 Phosphate Lyase Regulates Sensitivity of Pancreatic Beta-Cells to Lipotoxicity. Int J Mol Sci 2021; 22:ijms221910893. [PMID: 34639233 PMCID: PMC8509761 DOI: 10.3390/ijms221910893] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 09/28/2021] [Accepted: 10/04/2021] [Indexed: 12/29/2022] Open
Abstract
Elevated levels of free fatty acids (FFAs) have been related to pancreatic beta-cell failure in type 2 diabetes (T2DM), though the underlying mechanisms are not yet fully understood. FFAs have been shown to dysregulate formation of bioactive sphingolipids, such as ceramides and sphingosine-1 phosphate (S1P) in beta-cells. The aim of this study was to analyze the role of sphingosine-1 phosphate lyase (SPL), a key enzyme of the sphingolipid pathway that catalyzes an irreversible degradation of S1P, in the sensitivity of beta-cells to lipotoxicity. To validate the role of SPL in lipotoxicity, we modulated SPL expression in rat INS1E cells and in human EndoC-βH1 beta-cells. SPL overexpression in INS1E cells (INS1E-SPL), which are characterized by a moderate basal expression level of SPL, resulted in an acceleration of palmitate-mediated cell viability loss, proliferation inhibition and induction of oxidative stress. SPL overexpression affected the mRNA expression of ER stress markers and mitochondrial chaperones. In contrast to control cells, in INS1E-SPL cells no protective effect of oleate was detected. Moreover, Plin2 expression and lipid droplet formation were strongly reduced in OA-treated INS1E-SPL cells. Silencing of SPL in human EndoC-βH1 beta-cells, which are characterized by a significantly higher SPL expression as compared to rodent beta-cells, resulted in prevention of FFA-mediated caspase-3/7 activation. Our findings indicate that an adequate control of S1P degradation by SPL might be crucially involved in the susceptibility of pancreatic beta-cells to lipotoxicity.
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Aghelan Z, Kiani S, Nasiri A, Sadeghi M, Farrokhi A, Khodarahmi R. Factors Influencing Mitochondrial Function as a Key Mediator of Glucose-Induced Insulin Release: Highlighting Nicotinamide Nucleotide Transhydrogenase. INTERNATIONAL JOURNAL OF MOLECULAR AND CELLULAR MEDICINE 2020; 9:107-122. [PMID: 32934948 PMCID: PMC7489113 DOI: 10.22088/ijmcm.bums.9.2.107] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Accepted: 08/04/2020] [Indexed: 12/13/2022]
Abstract
Pancreatic β-cells recognize blood glucose changes and release insulin that is a peptide hormone responsible for stable glycemia. Diabetes, a chronic disorder of insulin insufficiency, leads to disturbed glucose homeostasis and multi-organ problems. Glucose and insulin are key markers in the follow-up and control of this disease. Mitochondrial metabolism of pancreatic beta cells is a crucial part of glucose-stimulated cascade of insulin secretion. Effective factors on β-cells mitochondrial function in production of compounds such as tricarboxylic acid intermediates, glutamate, nicotinamide adenine dinucleotide phosphate, and reactive oxygen species can have great effects on the secretion of insulin under diabetes. This review enhances our knowledge of factors influencing mitochondrial function as a key mediator of glucose-induced insulin release that accordingly will be helpful to further our understanding of the mechanisms implicated in the progressive beta cell failure that results in diabetes.
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Affiliation(s)
- Zahra Aghelan
- Department of Clinical Biochemistry, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Sara Kiani
- Medical Biology Research Center, Health Technology Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Abolfazl Nasiri
- Department of Clinical Biochemistry, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Masoud Sadeghi
- Medical Biology Research Center, Health Technology Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Alireza Farrokhi
- Medical Biology Research Center, Health Technology Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Reza Khodarahmi
- Medical Biology Research Center, Health Technology Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran
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Ko E, Um MY, Choi M, Han T, Kim IH, Shin S. Cassia tora Seed Improves Pancreatic Mitochondrial Function Leading to Recovery of Glucose Metabolism. THE AMERICAN JOURNAL OF CHINESE MEDICINE 2020; 48:615-629. [PMID: 32329641 DOI: 10.1142/s0192415x20500317] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Mitochondrial metabolism plays a crucial role in insulin resistance and insulin secretion in type 2 diabetes mellitus (T2D). Some studies have focused on how Cassia tora extracts affect insulin resistance and hyperglycemia. However, the effects of Cassia tora extracts on mitochondrial dysfunction associated with insulin secretion have not been well explained. In this study, well-known effective compounds extracted from Cassia tora using 70% ethanol were administered to a high-fat diet (HFD) fed mouse to examine the effects of Cassia tora ethanolic extracts (CSEE) on mitochondrial dysfunction in the pancreas. Furthermore, we examined how CSEE regulates the basal mechanism of insulin secretion through mitochondrial functions. Our experimental data suggest that pancreatic mitochondrial metabolism in HFD mice is enhanced to compensate for constrained glucose consumption. HFD-fed mice treated with CSEE showed improved pancreatic mitochondrial functions resulting in alleviation of insulin resistance at target tissue as well as basal hyperinsulinemia.
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Affiliation(s)
- Eun Ko
- Interdisciplinary Program of Bioenergy and Biomaterials, Graduate School, College of Engineering, College of Engineering, Chonnam National University, Gwangju 61186, Republic of Korea
| | - Min Young Um
- Division of Functional Food Research, Korea Food Research Institute, Wanju 55365, Republic of Korea
| | - Moonsung Choi
- Department of Optometry, College of Energy and Biotechnology, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea.,Convergence Institute of Biomaterials and Bioengineering, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea
| | - Taewon Han
- Division of Functional Food Research, Korea Food Research Institute, Wanju 55365, Republic of Korea
| | - In-Ho Kim
- Division of Functional Food Research, Korea Food Research Institute, Wanju 55365, Republic of Korea
| | - Sooim Shin
- Interdisciplinary Program of Bioenergy and Biomaterials, Graduate School, College of Engineering, College of Engineering, Chonnam National University, Gwangju 61186, Republic of Korea.,Department of Biotechnology and Bioengineering, College of Engineering, Chonnam National University, Gwangju 61186, Republic of Korea
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Substantial inter-individual variations in insulin secretion and sensitivity across the glucometabolic spectrum. Scandinavian Journal of Clinical and Laboratory Investigation 2020; 80:282-290. [PMID: 32134347 DOI: 10.1080/00365513.2020.1730433] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Impaired insulin secretion and action are important for development of type 2 diabetes (T2D) and metabolic syndrome (MetS). Despite recognized heterogeneity of these glucometabolic disorders, few data are available of biological variation in insulin secretion and action among individuals with T2D and MetS. The aim of this study was to explore the inter-individual variations using gold standard methods in a cross-sectional study of two independent cohorts of phenotypically well-characterized subjects. Cohort I included 486 subjects with MetS, and cohort II 62 subjects with established T2D. First phase insulin secretion was defined as the incremental area under the curve 0-8 min (iAUC0-8 min) during an intravenous glucose tolerance test (IVGTT). Insulin sensitivity was measured as the insulin sensitivity index (SI) modelled from IVGTT in cohort I, and in II as total glucose disposal (TGD) estimated from a euglycaemic-hyperinsulinaemic clamp. Variation is given as total range and, fold-variation between 5%- and 95%-percentile. The iAUC0-8 min ranged from -60 to 3397 mUL-1min-1 among subjects with MetS and from -263 to 1194 mUL-1min-1 in subjects with T2D, representing a more than 10-fold variation. Insulin sensitivity ranged from SI 0.19 to 15.29 (mU/L)-1min-1 among subjects with MetS and TGD 12.9-101.6 μmolkgFFM-1min-1 in subjects with T2D, representing a 6.8 and 5.5-fold variation, respectively. The other components of MetS; BMI, waist-hip ratio, HDL-cholesterol, triglycerides and blood pressure (BP), showed a 1.4-4.7-fold variation. In conclusion, our data demonstrated extensive inter-individual variations in insulin secretion and sensitivity. These variations may be essential to take into account when planning clinical research and treatment in subjects with T2D and MetS.
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Magalhães FO, Uber-Bucek E, Ceron PIB, Name TF, Coelho HE, Barbosa CHG, Carvalho T, Groppo M. Chronic treatment with hydroalcoholic extract of Plathymenia reticulata promotes islet hyperplasia and improves glycemic control in diabetic rats. EINSTEIN-SAO PAULO 2019; 17:eAO4635. [PMID: 31271592 PMCID: PMC6611089 DOI: 10.31744/einstein_journal/2019ao4635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 04/08/2019] [Indexed: 11/14/2022] Open
Abstract
Objective: To investigate the anti-hyperglycemic effects of Plathymenia reticulata hydroalcoholic extract and related changes in body weight, lipid profile and the pancreas. Methods: Diabetes was induced in 75 adult male Wistar rats via oral gavage of 65mg/Kg of streptozotocin. Rats were allocated to one of 8 groups, as follows: diabetic and control rats treated with water, diabetic and control rats treated with 100mg/kg or 200mg/kg of plant extract, and diabetic and control rats treated with glyburide. Treatment consisted of oral gavage for 30 days. Blood glucose levels and body weight were measured weekly. Animals were sacrificed and lipid profile and pancreatic tissue samples analyzed. Statistical analysis consisted of ANOVA, post-hoc Tukey-Kramer, paired Student's t and χ2 tests; the level of significance was set at 5%. Results: Extract gavage at 100mg/kg led to a decrease in blood glucose levels in diabetic rats in the second, third (198.71±65.27 versus 428.00±15.25) and fourth weeks (253.29±47.37 versus 443.22±42.72), body weight loss (13.22±5.70 versus 109.60±9.95) and lower cholesterol levels (58.75±3.13 versus 80.11±4.01) in control rats. Extract gavage at 200mg/Kg led to a decrease in glucose levels on the fourth week in diabetic rats, body weight loss in the second, third and fourth weeks in control rats, and lower cholesterol levels in diabetic and control rats. Islet hyperplasia (p=0.005) and pancreatic duct dilation (p=0.047) were observed in diabetic and control rats. Conclusion: Plathymenia extract reduced blood glucose levels in diabetic rats, and body weight in control rats, and promoted pancreatic islet hyperplasia in diabetic and control rats.
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Affiliation(s)
| | | | | | | | | | | | | | - Milton Groppo
- Universidade de São Paulo, Ribeirão Preto, SP, Brazil
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Gerst F, Wagner R, Oquendo MB, Siegel-Axel D, Fritsche A, Heni M, Staiger H, Häring HU, Ullrich S. What role do fat cells play in pancreatic tissue? Mol Metab 2019; 25:1-10. [PMID: 31113756 PMCID: PMC6600604 DOI: 10.1016/j.molmet.2019.05.001] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 04/10/2019] [Accepted: 05/01/2019] [Indexed: 02/07/2023] Open
Abstract
Background It is now generally accepted that obesity is a major risk factor for type 2 diabetes mellitus (T2DM). Hepatic steatosis in particular, as well as visceral and ectopic fat accumulation within tissues, is associated with the development of the disease. We recently presented the first study on isolated human pancreatic adipocytes and their interaction with islets [Gerst, F., Wagner, R., Kaiser, G., Panse, M., Heni, M., Machann, J., et al., 2017. Metabolic crosstalk between fatty pancreas and fatty liver: effects on local inflammation and insulin secretion. Diabetologia 60(11):2240–2251.]. The results indicate that the function of adipocytes depends on the overall metabolic status in humans which, in turn, differentially affects islet hormone release. Scope of Review This review summarizes former and recent studies on factors derived from adipocytes and their effects on insulin-secreting β-cells, with particular emphasis on the human pancreas. The adipocyte secretome is discussed with a special focus on its influence on insulin secretion, β-cell survival and apoptotic β-cell death. Major Conclusions Human pancreatic adipocytes store lipids and release adipokines, metabolites, and pro-inflammatory molecules in response to the overall metabolic, humoral, and neuronal status. The differentially regulated adipocyte secretome impacts on endocrine function, i.e., insulin secretion, β-cell survival and death which interferes with glycemic control. This review attempts to explain why the extent of pancreatic steatosis is associated with reduced insulin secretion in some studies but not in others.
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Affiliation(s)
- Felicia Gerst
- German Center for Diabetes Research (DZD), Tübingen, Germany; Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Robert Wagner
- German Center for Diabetes Research (DZD), Tübingen, Germany; Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, Eberhard Karls University of Tübingen, Tübingen, Germany; Department of Internal Medicine IV, Division of Endocrinology, Diabetology, and Nephrology, University Hospital Tübingen, Tübingen, Germany
| | - Morgana Barroso Oquendo
- German Center for Diabetes Research (DZD), Tübingen, Germany; Department of Internal Medicine IV, Division of Endocrinology, Diabetology, and Nephrology, University Hospital Tübingen, Tübingen, Germany
| | - Dorothea Siegel-Axel
- German Center for Diabetes Research (DZD), Tübingen, Germany; Department of Internal Medicine IV, Division of Endocrinology, Diabetology, and Nephrology, University Hospital Tübingen, Tübingen, Germany
| | - Andreas Fritsche
- German Center for Diabetes Research (DZD), Tübingen, Germany; Department of Internal Medicine IV, Division of Endocrinology, Diabetology, and Nephrology, University Hospital Tübingen, Tübingen, Germany
| | - Martin Heni
- German Center for Diabetes Research (DZD), Tübingen, Germany; Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, Eberhard Karls University of Tübingen, Tübingen, Germany; Department of Internal Medicine IV, Division of Endocrinology, Diabetology, and Nephrology, University Hospital Tübingen, Tübingen, Germany
| | - Harald Staiger
- German Center for Diabetes Research (DZD), Tübingen, Germany; Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, Eberhard Karls University of Tübingen, Tübingen, Germany; Institute of Pharmaceutical Sciences, Department of Pharmacy and Biochemistry, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Hans-Ulrich Häring
- German Center for Diabetes Research (DZD), Tübingen, Germany; Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, Eberhard Karls University of Tübingen, Tübingen, Germany; Department of Internal Medicine IV, Division of Endocrinology, Diabetology, and Nephrology, University Hospital Tübingen, Tübingen, Germany
| | - Susanne Ullrich
- German Center for Diabetes Research (DZD), Tübingen, Germany; Institute for Diabetes Research and Metabolic Diseases, Helmholtz Center Munich, Eberhard Karls University of Tübingen, Tübingen, Germany.
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The role of cardiolipin concentration and acyl chain composition on mitochondrial inner membrane molecular organization and function. Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1864:1039-1052. [PMID: 30951877 DOI: 10.1016/j.bbalip.2019.03.012] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 03/19/2019] [Accepted: 03/30/2019] [Indexed: 12/28/2022]
Abstract
Cardiolipin (CL) is a key phospholipid of the mitochondria. A loss of CL content and remodeling of CL's acyl chains is observed in several pathologies. Strong shifts in CL concentration and acyl chain composition would presumably disrupt mitochondrial inner membrane biophysical organization. However, it remains unclear in the literature as to which is the key regulator of mitochondrial membrane biophysical properties. We review the literature to discriminate the effects of CL concentration and acyl chain composition on mitochondrial membrane organization. A widely applicable theme emerges across several pathologies, including cardiovascular diseases, diabetes, Barth syndrome, and neurodegenerative ailments. The loss of CL, often accompanied by increased levels of lyso-CLs, impairs mitochondrial inner membrane organization. Modest remodeling of CL acyl chains is not a major driver of impairments and only in cases of extreme remodeling is there an influence on membrane properties.
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Chitooligosaccharide Biguanide Repairs Islet β‐Cell Dysfunction by Activating the IRS‐2/PI3K/Akt Signaling Pathway in Type 2 Diabetic Rats. ADVANCED THERAPEUTICS 2019. [DOI: 10.1002/adtp.201800136] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Zheng S, Ren X, Han T, Chen Y, Qiu H, Liu W, Hu Y. Fenofibrate attenuates fatty acid-induced islet β-cell dysfunction and apoptosis via inhibiting the NF-κB/MIF dependent inflammatory pathway. Metabolism 2017; 77:23-38. [PMID: 28941594 DOI: 10.1016/j.metabol.2017.09.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2017] [Revised: 09/04/2017] [Accepted: 09/05/2017] [Indexed: 01/01/2023]
Abstract
BACKGROUND Fatty acid-induced lipotoxicity and macrophage migration inhibitory factor (MIF) affect pancreatic β-cell function, and may promote the development of diabetes mellitus. However, the association of lipotoxicity with MIF and the effect of Fenofibrate on β-cell function remain unknown. METHODS LPL+/- mice and MIN6 cells stimulated with palmitic acid (PA) were utilized as models of lipid metabolism disorders. Factors associated with insulin secretion and apoptosis were assessed in the presence or absence of Fenofibrate. The possible mechanisms of lipotoxicity-induced β-cell dysfunction were also explored. RESULTS Fenofibrate effectively improved lipid accumulation in pancreatic β-cells, increased glucose-stimulated insulin secretion and β-cell mass, and significantly downregulated pro-apoptotic molecules, at the gene and protein levels, both in vivo and in vitro. Additionally, elevated MIF levels in serum from LPL+/- mice and PA-treated MIN6 cells were starkly decreased after Fenofibrate administration. Mechanistic analysis indicated that NF-κB signaling was remarkably triggered, which could further activate MIF transcription. Furthermore, Fenofibrate exerted beneficial effects on fatty acid-induced β-cell dysfunction likely by inhibiting the NF-κB/MIF dependent inflammatory response. CONCLUSIONS Fenofibrate ameliorates lipotoxicity-induced β-cell dysfunction and apoptosis by inhibiting the NF-κB/MIF inflammatory pathway. These findings provide novel insights into the treatment of lipotoxicity-induced metabolic disorders.
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Affiliation(s)
- Shuang Zheng
- Department of Endocrinology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
| | - Xingxing Ren
- Department of Endocrinology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
| | - Tingting Han
- Department of Endocrinology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
| | - Yawen Chen
- Department of Endocrinology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
| | - Huiying Qiu
- Department of Endocrinology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China
| | - Wei Liu
- Department of Endocrinology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China.
| | - Yaomin Hu
- Department of Endocrinology, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, China.
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12
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Mega C, Teixeira-de-Lemos E, Fernandes R, Reis F. Renoprotective Effects of the Dipeptidyl Peptidase-4 Inhibitor Sitagliptin: A Review in Type 2 Diabetes. J Diabetes Res 2017; 2017:5164292. [PMID: 29098166 PMCID: PMC5643039 DOI: 10.1155/2017/5164292] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2017] [Accepted: 07/12/2017] [Indexed: 12/13/2022] Open
Abstract
Diabetic nephropathy (DN) is now the single commonest cause of end-stage renal disease (ESRD) worldwide and one of the main causes of death in diabetic patients. It is also acknowledged as an independent risk factor for cardiovascular disease (CVD). Since sitagliptin was approved, many studies have been carried out revealing its ability to not only improve metabolic control but also ameliorate dysfunction in various diabetes-targeted organs, especially the kidney, due to putative underlying cytoprotective properties, namely, its antiapoptotic, antioxidant, anti-inflammatory, and antifibrotic properties. Despite overall recommendations, many patients spend a long time well outside the recommended glycaemic range and, therefore, have an increased risk for developing micro- and macrovascular complications. Currently, it is becoming clearer that type 2 diabetes mellitus (T2DM) management must envision not only the improvement in glycaemic control but also, and particularly, the prevention of pancreatic deterioration and the evolution of complications, such as DN. This review aims to provide an overview of the current knowledge in the field of renoprotective actions of sitagliptin, namely, improvement in diabetic dysmetabolism, hemodynamic factors, renal function, diabetic kidney lesions, and cytoprotective properties.
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Affiliation(s)
- Cristina Mega
- Agrarian School of Viseu (ESAV), Polytechnic Institute of Viseu (IPV), 3500-606 Viseu, Portugal
- Centre for the Study of Education, Technologies and Health (CI&DETS), Polytechnic Institute of Viseu (IPV), 3500-606 Viseu, Portugal
- Institute of Pharmacology and Experimental Therapeutics and Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal
| | - Edite Teixeira-de-Lemos
- Agrarian School of Viseu (ESAV), Polytechnic Institute of Viseu (IPV), 3500-606 Viseu, Portugal
- Centre for the Study of Education, Technologies and Health (CI&DETS), Polytechnic Institute of Viseu (IPV), 3500-606 Viseu, Portugal
| | - Rosa Fernandes
- Institute of Pharmacology and Experimental Therapeutics and Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal
- CNC.IBILI Research Consortium, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Flávio Reis
- Institute of Pharmacology and Experimental Therapeutics and Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal
- CNC.IBILI Research Consortium, University of Coimbra, 3004-504 Coimbra, Portugal
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Kawamori D, Shirakawa J, Liew CW, Hu J, Morioka T, Duttaroy A, Burkey B, Kulkarni RN. GLP-1 signalling compensates for impaired insulin signalling in regulating beta cell proliferation in βIRKO mice. Diabetologia 2017; 60:1442-1453. [PMID: 28526921 PMCID: PMC5508991 DOI: 10.1007/s00125-017-4303-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 04/18/2017] [Indexed: 01/08/2023]
Abstract
AIMS/HYPOTHESIS We aimed to investigate potential interactions between insulin and glucagon-like peptide (GLP)-1 signalling pathways in the regulation of beta cell-cycle dynamics in vivo, in the context of the therapeutic potential of GLP-1 to modulate impaired beta cell function. METHODS Beta cell-specific insulin receptor knockout (βIRKO) mice, which exhibit beta cell dysfunction and an age-dependent decrease in beta cell mass, were treated with the dipeptidyl peptidase-4 inhibitor vildagliptin. Following this, glucose homeostasis and beta cell proliferation were evaluated and underlying molecular mechanisms were investigated. RESULTS The sustained elevation in circulating GLP-1 levels, caused by treatment of the knockout mice with vildagliptin for 6 weeks, significantly improved glucose tolerance secondary to enhanced insulin secretion and proliferation of beta cells. Treating βIRKO beta cell lines with the GLP-1 analogue, exendin-4, promoted Akt phosphorylation and protein expression of cyclins A, D1 and E two- to threefold, in addition to cyclin D2. Pancreases from the vildagliptin-treated βIRKO mice exhibited increased cyclin D1 expression, while cyclin D2 expression was impaired. CONCLUSIONS/INTERPRETATION Activation of GLP-1 signalling compensates for impaired growth factor (insulin) signalling and enhances expression of cyclins to promote beta cell proliferation. Together, these data indicate the potential of GLP-1-related therapies to enhance beta cell proliferation and promote beneficial outcomes in models with dysfunctional beta cells.
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Affiliation(s)
- Dan Kawamori
- Section of Islet Cell and Regenerative Biology, Joslin Diabetes Center, Room 410, One Joslin Place, Boston, MA, 02215, USA
- Department of Metabolic Medicine, Graduate School of Medicine, Osaka University, Osaka, Japan
- Medical Education Center, Faculty of Medicine, Osaka University, Osaka, Japan
| | - Jun Shirakawa
- Section of Islet Cell and Regenerative Biology, Joslin Diabetes Center, Room 410, One Joslin Place, Boston, MA, 02215, USA
| | - Chong Wee Liew
- Section of Islet Cell and Regenerative Biology, Joslin Diabetes Center, Room 410, One Joslin Place, Boston, MA, 02215, USA
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL, USA
| | - Jiang Hu
- Section of Islet Cell and Regenerative Biology, Joslin Diabetes Center, Room 410, One Joslin Place, Boston, MA, 02215, USA
| | - Tomoaki Morioka
- Section of Islet Cell and Regenerative Biology, Joslin Diabetes Center, Room 410, One Joslin Place, Boston, MA, 02215, USA
- Department of Metabolism, Endocrinology and Molecular Medicine, Graduate School of Medicine, Osaka City University, Osaka, Japan
| | - Alokesh Duttaroy
- Cardiovascular & Metabolic Diseases, Novartis Institutes for Biomedical Research, Inc., Cambridge, MA, USA
| | | | - Rohit N Kulkarni
- Section of Islet Cell and Regenerative Biology, Joslin Diabetes Center, Room 410, One Joslin Place, Boston, MA, 02215, USA.
- Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
- Harvard Stem Cell Institute, Boston, MA, USA.
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14
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Tahrani AA, Barnett AH, Bailey CJ. Pharmacology and therapeutic implications of current drugs for type 2 diabetes mellitus. Nat Rev Endocrinol 2016; 12:566-92. [PMID: 27339889 DOI: 10.1038/nrendo.2016.86] [Citation(s) in RCA: 244] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Type 2 diabetes mellitus (T2DM) is a global epidemic that poses a major challenge to health-care systems. Improving metabolic control to approach normal glycaemia (where practical) greatly benefits long-term prognoses and justifies early, effective, sustained and safety-conscious intervention. Improvements in the understanding of the complex pathogenesis of T2DM have underpinned the development of glucose-lowering therapies with complementary mechanisms of action, which have expanded treatment options and facilitated individualized management strategies. Over the past decade, several new classes of glucose-lowering agents have been licensed, including glucagon-like peptide 1 receptor (GLP-1R) agonists, dipeptidyl peptidase 4 (DPP-4) inhibitors and sodium/glucose cotransporter 2 (SGLT2) inhibitors. These agents can be used individually or in combination with well-established treatments such as biguanides, sulfonylureas and thiazolidinediones. Although novel agents have potential advantages including low risk of hypoglycaemia and help with weight control, long-term safety has yet to be established. In this Review, we assess the pharmacokinetics, pharmacodynamics and safety profiles, including cardiovascular safety, of currently available therapies for management of hyperglycaemia in patients with T2DM within the context of disease pathogenesis and natural history. In addition, we briefly describe treatment algorithms for patients with T2DM and lessons from present therapies to inform the development of future therapies.
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Affiliation(s)
- Abd A Tahrani
- Centre of Endocrinology, Diabetes and Metabolism, 2nd Floor, Institute of Biomedical Research, University of Birmingham, Birmingham, B15 2TT, UK
- Department of Diabetes and Endocrinology, Heart of England NHS Foundation Trust, Birmingham, B9 5SS, UK
| | - Anthony H Barnett
- Centre of Endocrinology, Diabetes and Metabolism, 2nd Floor, Institute of Biomedical Research, University of Birmingham, Birmingham, B15 2TT, UK
- Department of Diabetes and Endocrinology, Heart of England NHS Foundation Trust, Birmingham, B9 5SS, UK
| | - Clifford J Bailey
- School of Life and Health Sciences, Aston University, Birmingham, B4 7ET, UK
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Kusminski CM, Chen S, Ye R, Sun K, Wang QA, Spurgin SB, Sanders PE, Brozinick JT, Geldenhuys WJ, Li WH, Unger RH, Scherer PE. MitoNEET-Parkin Effects in Pancreatic α- and β-Cells, Cellular Survival, and Intrainsular Cross Talk. Diabetes 2016; 65:1534-55. [PMID: 26895793 PMCID: PMC5310214 DOI: 10.2337/db15-1323] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 02/06/2016] [Indexed: 12/16/2022]
Abstract
Mitochondrial metabolism plays an integral role in glucose-stimulated insulin secretion (GSIS) in β-cells. In addition, the diabetogenic role of glucagon released from α-cells plays a major role in the etiology of both type 1 and type 2 diabetes because unopposed hyperglucagonemia is a pertinent contributor to diabetic hyperglycemia. Titrating expression levels of the mitochondrial protein mitoNEET is a powerful approach to fine-tune mitochondrial capacity of cells. Mechanistically, β-cell-specific mitoNEET induction causes hyperglycemia and glucose intolerance due to activation of a Parkin-dependent mitophagic pathway, leading to the formation of vacuoles and uniquely structured mitophagosomes. Induction of mitoNEET in α-cells leads to fasting-induced hypoglycemia and hypersecretion of insulin during GSIS. MitoNEET-challenged α-cells exert potent antiapoptotic effects on β-cells and prevent cellular dysfunction associated with mitoNEET overexpression in β-cells. These observations identify that reduced mitochondrial function in α-cells exerts potently protective effects on β-cells, preserving β-cell viability and mass.
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Affiliation(s)
- Christine M Kusminski
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX
| | - Shiuhwei Chen
- Department of Cell Biology, The University of Texas Southwestern Medical Center, Dallas, TX Department of Biochemistry, The University of Texas Southwestern Medical Center, Dallas, TX
| | - Risheng Ye
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX
| | - Kai Sun
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX
| | - Qiong A Wang
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX
| | - Stephen B Spurgin
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX
| | - Phillip E Sanders
- Lilly Research Laboratories, Division of Eli Lilly and Co., Indianapolis, IN
| | - Joseph T Brozinick
- Lilly Research Laboratories, Division of Eli Lilly and Co., Indianapolis, IN
| | - Werner J Geldenhuys
- Department of Pharmaceutical Sciences, School of Pharmacy, West Virginia University, Morgantown, WV
| | - Wen-Hong Li
- Department of Cell Biology, The University of Texas Southwestern Medical Center, Dallas, TX Department of Biochemistry, The University of Texas Southwestern Medical Center, Dallas, TX
| | - Roger H Unger
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX
| | - Philipp E Scherer
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX Department of Cell Biology, The University of Texas Southwestern Medical Center, Dallas, TX
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16
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Lyon J, Manning Fox JE, Spigelman AF, Kim R, Smith N, O'Gorman D, Kin T, Shapiro AMJ, Rajotte RV, MacDonald PE. Research-Focused Isolation of Human Islets From Donors With and Without Diabetes at the Alberta Diabetes Institute IsletCore. Endocrinology 2016; 157:560-9. [PMID: 26653569 DOI: 10.1210/en.2015-1562] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Recent years have seen an increased focus on human islet biology, and exciting findings in the stem cell and genomic arenas highlight the need to define the key features of mature human islets and β-cells. Donor and organ procurement parameters impact human islet yield, although for research purposes islet yield may be secondary in importance to islet function. We examined the feasibility of a research-only human islet isolation, distribution, and biobanking program and whether key criteria such as cold ischemia time (CIT) and metabolic status may be relaxed and still allow successful research-focused isolations, including from donors with type 1 diabetes and type 2 diabetes. Through 142 isolations over approximately 5 years, we confirm that CIT and glycated hemoglobin each have a weak negative impacts on isolation purity and yield, and extending CIT beyond the typical clinical isolation cutoff of 12 hours (to ≥ 18 h) had only a modest impact on islet function. Age and glycated hemoglobin/type 2 diabetes status negatively impacted secretory function; however, these and other biological (sex, body mass index) and procurement/isolation variables (CIT, time in culture) appear to make only a small contribution to the heterogeneity of human islet function. This work demonstrates the feasibility of extending acceptable CIT for research-focused human islet isolation and highlights the biological variation in function of human islets from donors with and without diabetes.
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Affiliation(s)
- James Lyon
- Alberta Diabetes Institute IsletCore (J.L., J.E.M.F., P.E.M.) and Departments of Pharmacology (J.E.M.F., A.F.S., R.K., N.S., P.E.M.) and Surgery (D.O., T.K., A.M.J.S., R.V.R.), University of Alberta, Edmonton, Canada T6G 2E1
| | - Jocelyn E Manning Fox
- Alberta Diabetes Institute IsletCore (J.L., J.E.M.F., P.E.M.) and Departments of Pharmacology (J.E.M.F., A.F.S., R.K., N.S., P.E.M.) and Surgery (D.O., T.K., A.M.J.S., R.V.R.), University of Alberta, Edmonton, Canada T6G 2E1
| | - Aliya F Spigelman
- Alberta Diabetes Institute IsletCore (J.L., J.E.M.F., P.E.M.) and Departments of Pharmacology (J.E.M.F., A.F.S., R.K., N.S., P.E.M.) and Surgery (D.O., T.K., A.M.J.S., R.V.R.), University of Alberta, Edmonton, Canada T6G 2E1
| | - Ryekjang Kim
- Alberta Diabetes Institute IsletCore (J.L., J.E.M.F., P.E.M.) and Departments of Pharmacology (J.E.M.F., A.F.S., R.K., N.S., P.E.M.) and Surgery (D.O., T.K., A.M.J.S., R.V.R.), University of Alberta, Edmonton, Canada T6G 2E1
| | - Nancy Smith
- Alberta Diabetes Institute IsletCore (J.L., J.E.M.F., P.E.M.) and Departments of Pharmacology (J.E.M.F., A.F.S., R.K., N.S., P.E.M.) and Surgery (D.O., T.K., A.M.J.S., R.V.R.), University of Alberta, Edmonton, Canada T6G 2E1
| | - Doug O'Gorman
- Alberta Diabetes Institute IsletCore (J.L., J.E.M.F., P.E.M.) and Departments of Pharmacology (J.E.M.F., A.F.S., R.K., N.S., P.E.M.) and Surgery (D.O., T.K., A.M.J.S., R.V.R.), University of Alberta, Edmonton, Canada T6G 2E1
| | - Tatsuya Kin
- Alberta Diabetes Institute IsletCore (J.L., J.E.M.F., P.E.M.) and Departments of Pharmacology (J.E.M.F., A.F.S., R.K., N.S., P.E.M.) and Surgery (D.O., T.K., A.M.J.S., R.V.R.), University of Alberta, Edmonton, Canada T6G 2E1
| | - A M James Shapiro
- Alberta Diabetes Institute IsletCore (J.L., J.E.M.F., P.E.M.) and Departments of Pharmacology (J.E.M.F., A.F.S., R.K., N.S., P.E.M.) and Surgery (D.O., T.K., A.M.J.S., R.V.R.), University of Alberta, Edmonton, Canada T6G 2E1
| | - Raymond V Rajotte
- Alberta Diabetes Institute IsletCore (J.L., J.E.M.F., P.E.M.) and Departments of Pharmacology (J.E.M.F., A.F.S., R.K., N.S., P.E.M.) and Surgery (D.O., T.K., A.M.J.S., R.V.R.), University of Alberta, Edmonton, Canada T6G 2E1
| | - Patrick E MacDonald
- Alberta Diabetes Institute IsletCore (J.L., J.E.M.F., P.E.M.) and Departments of Pharmacology (J.E.M.F., A.F.S., R.K., N.S., P.E.M.) and Surgery (D.O., T.K., A.M.J.S., R.V.R.), University of Alberta, Edmonton, Canada T6G 2E1
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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: 23] [Impact Index Per Article: 2.6] [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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Alejandro EU, Bozadjieva N, Kumusoglu D, Abdulhamid S, Levine H, Haataja L, Vadrevu S, Satin LS, Arvan P, Bernal-Mizrachi E. Disruption of O-linked N-Acetylglucosamine Signaling Induces ER Stress and β Cell Failure. Cell Rep 2015; 13:2527-2538. [PMID: 26673325 PMCID: PMC4839001 DOI: 10.1016/j.celrep.2015.11.020] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Revised: 09/22/2015] [Accepted: 11/03/2015] [Indexed: 11/30/2022] Open
Abstract
Nutrient levels dictate the activity of O-linked N-acetylglucosamine transferase (OGT) to regulate O-GlcNAcylation, a post-translational modification mechanism to "fine-tune" intracellular signaling and metabolic status. However, the requirement of O-GlcNAcylation for maintaining glucose homeostasis by regulating pancreatic β cell mass and function is unclear. Here, we reveal that mice lacking β cell OGT (βOGT-KO) develop diabetes and β cell failure. βOGT-KO mice demonstrated increased ER stress and distended ER architecture, and these changes ultimately caused the loss of β cell mass due to ER-stress-induced apoptosis and decreased proliferation. Akt1/2 signaling was also dampened in βOGT-KO islets. The mechanistic role of these processes was demonstrated by rescuing the phenotype of βOGT-KO mice with concomitant Chop gene deletion or genetic reconstitution of Akt2. These findings identify OGT as a regulator of β cell mass and function and provide a direct link between O-GlcNAcylation and β cell survival by regulation of ER stress responses and modulation of Akt1/2 signaling.
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Affiliation(s)
- Emilyn U Alejandro
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, University of Michigan, Ann Arbor, MI 48109-0678, USA
| | - Nadejda Bozadjieva
- Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, MI 48109-0678, USA
| | - Doga Kumusoglu
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, University of Michigan, Ann Arbor, MI 48109-0678, USA
| | - Sarah Abdulhamid
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, University of Michigan, Ann Arbor, MI 48109-0678, USA
| | - Hannah Levine
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, University of Michigan, Ann Arbor, MI 48109-0678, USA
| | - Leena Haataja
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, University of Michigan, Ann Arbor, MI 48109-0678, USA
| | - Suryakiran Vadrevu
- Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109-0678, USA
| | - Leslie S Satin
- Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, MI 48109-0678, USA
| | - Peter Arvan
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, University of Michigan, Ann Arbor, MI 48109-0678, USA
| | - Ernesto Bernal-Mizrachi
- Department of Internal Medicine, Division of Metabolism, Endocrinology and Diabetes, University of Michigan, Ann Arbor, MI 48109-0678, USA; VA Ann Arbor Healthcare System, Ann Arbor, MI 48109-0678, USA.
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20
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Kokil GR, Veedu RN, Ramm GA, Prins JB, Parekh HS. Type 2 diabetes mellitus: limitations of conventional therapies and intervention with nucleic acid-based therapeutics. Chem Rev 2015; 115:4719-43. [PMID: 25918949 DOI: 10.1021/cr5002832] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Ganesh R Kokil
- †School of Pharmacy, Pharmacy Australia Centre of Excellence, The University of Queensland, Brisbane, QLD 4102, Australia
| | - Rakesh N Veedu
- §Center for Comparative Genomics, Murdoch University, 90 South Street, Murdoch, WA 6150, Australia.,∥Western Australian Neuroscience Research Institute, Perth, WA 6150, Australia.,‡School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane QLD 4072 Australia
| | - Grant A Ramm
- ⊥The Hepatic Fibrosis Group, QIMR Berghofer Medical Research Institute, Brisbane, QLD 4006, Australia.,#Faculty of Medicine and Biomedical Sciences, The University of Queensland, Brisbane, QLD 4006, Australia
| | - Johannes B Prins
- ∇Mater Research Institute, The University of Queensland, Brisbane, QLD 4101, Australia
| | - Harendra S Parekh
- †School of Pharmacy, Pharmacy Australia Centre of Excellence, The University of Queensland, Brisbane, QLD 4102, Australia
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Sun J, Cui J, He Q, Chen Z, Arvan P, Liu M. Proinsulin misfolding and endoplasmic reticulum stress during the development and progression of diabetes. Mol Aspects Med 2015; 42:105-18. [PMID: 25579745 PMCID: PMC4404191 DOI: 10.1016/j.mam.2015.01.001] [Citation(s) in RCA: 119] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 12/31/2014] [Accepted: 01/02/2015] [Indexed: 02/06/2023]
Abstract
To maintain copious insulin granule stores in the face of ongoing metabolic demand, pancreatic beta cells must produce large quantities of proinsulin, the insulin precursor. Proinsulin biosynthesis can account for up to 30-50% of total cellular protein synthesis of beta cells. This puts pressure on the beta cell secretory pathway, especially the endoplasmic reticulum (ER), where proinsulin undergoes its initial folding, including the formation of three evolutionarily conserved disulfide bonds. In normal beta cells, up to 20% of newly synthesized proinsulin may fail to reach its native conformation, suggesting that proinsulin is a misfolding-prone protein. Misfolded proinsulin molecules can either be refolded to their native structure or degraded through ER associated degradation (ERAD) and autophagy. These degraded molecules decrease proinsulin yield but do not otherwise compromise beta cell function. However, under certain pathological conditions, proinsulin misfolding increases, exceeding the genetically determined threshold of beta cells to handle the misfolded protein load. This results in accumulation of misfolded proinsulin in the ER - a causal factor leading to beta cell failure and diabetes. In patients with Mutant INS-gene induced diabetes of Youth (MIDY), increased proinsulin misfolding due to insulin gene mutations is the primary defect operating as a "first hit" to beta cells. Additionally, increased proinsulin misfolding can be secondary to an unfavorable ER folding environment due to genetic and/or environmental factors. Under these conditions, increased wild-type proinsulin misfolding becomes a "second hit" to the ER and beta cells, aggravating beta cell failure and diabetes. In this article, we describe our current understanding of the normal proinsulin folding pathway in the ER, and then review existing links between proinsulin misfolding, ER dysfunction, and beta cell failure in the development and progression of type 2, type 1, and some monogenic forms of diabetes.
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Affiliation(s)
- Jinhong Sun
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan, Ann Arbor, MI 48105, USA
| | - Jingqiu Cui
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin 300052, China
| | - Qing He
- Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin 300052, China
| | - Zheng Chen
- School of Life Sciences, Northeast Normal University, Changchun, Jilin 130024, China
| | - Peter Arvan
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan, Ann Arbor, MI 48105, USA.
| | - Ming Liu
- Division of Metabolism, Endocrinology & Diabetes, University of Michigan, Ann Arbor, MI 48105, USA; Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin 300052, China.
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Altaf QA, Barnett AH, Tahrani AA. Novel therapeutics for type 2 diabetes: insulin resistance. Diabetes Obes Metab 2015; 17:319-34. [PMID: 25308775 DOI: 10.1111/dom.12400] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Revised: 09/23/2014] [Accepted: 10/04/2014] [Indexed: 12/19/2022]
Abstract
Insulin resistance (IR) plays an important role in the pathogenesis of type 2 diabetes (T2D) and cardiovascular disease. Hence improving IR is a major target of treatment in patients with T2D. Obesity and lack of exercise are major causes of IR. However, recent evidence implicates sleep disorders and disorders of the circadian rhythm in the pathogenesis of IR. Weight loss and lifestyle changes are the cornerstone and most effective treatments of IR, but adherence and patient's acceptability are poor. Bariatric surgery results in significant and sustainable long-term weight loss associated with beneficial impact on IR and glucose metabolism, making this an attractive treatment option for patients with T2D. Currently available pharmacological options targeting IR (such as metformin and thiazolidinediones) do not maintain glycaemic measures within targets long term and can be associated with significant side effects. Over the last two decades, many pharmacological agents targeting different aspects of the insulin signalling pathway were developed to improve IR, but only a minority reached clinical trials. Such treatments need to be specific and reversible as many of the components of the insulin signalling pathway are involved in other cellular functions such as apoptosis. Recent evidence highlighted the role of circadian rhythm and sleep-related disorders in the pathogenesis of IR. In this article, we review the latest developments in the pharmacological and non-pharmacological interventions targeting IR including bariatric surgery. We will also review the role of circadian rhythm and sleep-related disorders in the development and treatment of IR.
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Affiliation(s)
- Q-A Altaf
- Department of Diabetes and Endocrinology, Heart of England NHS Foundation Trust, Birmingham, UK; Centre of Endocrinology, Diabetes and Metabolism, University of Birmingham, Birmingham, UK
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Wang D, Tian M, Qi Y, Chen G, Xu L, Zou X, Wang K, Dong H, Lu F. Jinlida granule inhibits palmitic acid induced-intracellular lipid accumulation and enhances autophagy in NIT-1 pancreatic β cells through AMPK activation. JOURNAL OF ETHNOPHARMACOLOGY 2015; 161:99-107. [PMID: 25510732 DOI: 10.1016/j.jep.2014.12.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Revised: 11/06/2014] [Accepted: 12/01/2014] [Indexed: 06/04/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Jinlida granule (JLDG), composed of seventeen Chinese medical herbs, is a widely used Chinese herbal prescription for treating diabetes mellitus. However, the mechanism underlying this effect remains unclear. To determine the main components in JLDG and to explore the effect of JLDG on autophagy and lipid accumulation in NIT-1 pancreatic β cells exposed to politic acid (PA) through AMP activated protein kinase (AMPK) signaling pathway. MATERIALS AND METHODS JLDG was prepared and the main components contained in the granules were identified by ultra performance liquid chromatography (UPLC) fingerprint. Intracellular lipid accumulation in NIT-1 cells was induced by culturing with medium containing PA. Intracellular lipid droplets were observed by Oil Red O staining and triglyceride (TG) content was measured by colorimetric assay. The formation of autophagosomes was observed under transmission electron microscope. The expression of AMPK and phospho-AMPK (pAMPK) proteins as well as its downstream fatty acid metabolism-related proteins (fatty acid synthase, FAS; acetyl-coA carboxylase, ACC; carnitine acyltransferase 1, CPT-1) and autophagy-related genes (mammal target of rapamycin, mTOR; tuberous sclerosis complex 1, TSC1; microtubule-associated protein 1 light chain 3, LC3-II) were determined by Western blot. The expression of sterol regulating element binding protein 1c (SREBP-1c) mRNA was examined by real time PCR (RT-PCR). RESULTS Our data showed that JLDG could significantly reduce PA-induced intracellular lipid accumulation in NIT-1 pancreatic β cells. This effect was associated with increased protein expression of pAMPK and AMPK in NIT-1 cells. Treatment with JLDG also decreased the expression of AMPK downstream lipogenic genes (SREBP-1c mRNA, FAS and ACC proteins) whereas increased the expression of fatty acid oxidation gene (CPT-1 protein). Additionally, JLDG-treated cells displayed a markedly increase in the number of autophagosomes which was accompanied by the down-regulation of mTOR and the up-regulation of TSC1 and LC3-II proteins expression. However, when AMPK phosphorylation was inhibited by Compound C, JLDG supplementation did not exhibit any effect on the expression of these AMPK downstream molecules in NIT-1 cells. CONCLUSIONS The results suggest that JLDG could reduce intracellular lipid accumulation and enhance the autophagy in NIT-1 pancreatic β cells cultured with PA. The mechanism is possibly mediated by AMPK activation.
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Affiliation(s)
- Dingkun Wang
- Institute of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Min Tian
- Institute of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Yuan Qi
- Shijiazhuang YiLing Pharmaceutical Co., Ltd., Shijiazhuang, Hebei 050035, China
| | - Guang Chen
- Department of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Lijun Xu
- Institute of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Xin Zou
- Institute of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Kaifu Wang
- Institute of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China
| | - Hui Dong
- Institute of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China.
| | - Fuer Lu
- Institute of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China.
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Patel M, Gleason A, O'Malley S, Connolly B, Suresch D, Virostko J, Phillips N, Lin SA, Chen TB, Klimas M, Hargreaves RJ, Sur C, Williams DL, Powers AC, Bednar B. Non-invasive bioluminescence imaging of β-cell function in obese-hyperglycemic [ob/ob] mice. PLoS One 2014; 9:e106693. [PMID: 25198535 PMCID: PMC4157804 DOI: 10.1371/journal.pone.0106693] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Accepted: 08/01/2014] [Indexed: 01/09/2023] Open
Abstract
Background Type 2 diabetes results from failure of the β-cells to compensate for increased insulin demand due to abnormal levels of metabolic factors. The ob/ob(lep-/-) mouse has been extensively studied as an animal model of type 2 diabetes. Previous studies have shown a correlation between β-cell function and bioluminescent imaging in lean genetically engineered mice. The ability to noninvasively monitor β-cell function in ob/ob mice could provide new information on β-cell regulation in type 2 diabetes. Methods To create the B6 Albino ob/ob MIP-luc mice (ob/ob-luc), the ob/ob mouse was crossed with the CD1 MIP-luc mouse. All mice were backcrossed over multiple generations to ensure the genetic background of the transgenic mice was over 96% similar to the background of the original ob/ob mouse. Animal weight, blood glucose levels, insulin in plasma, and in vivo bioluminescence (BLI) were monitored weekly or biweekly for up to 70 weeks of age. BL imaging was performed using IVIS Spectrum (Perkin Elmer) and calculated by integrating the bioluminescence signal between 5 and 10 min after i.v. injection of D-luciferin. Insulin immunohistochemistry determined islet beta cell count and insulin secretion assay determined islet insulin function. Results There were significant increases in BLI and insulin levels as the ob/ob-luc mice aged while glucose levels gradually decreased. Ob/ob-luc were sacrificed at different time points to determine ex vivo BLI, islet function and total β-cell numbers using a cell counting training algorithm developed for the Vectra image analysis system (Perkin Elmer). The number of β-cells increased as the mice aged and all three ex vivo measurements correlated with BLI. Conclusions The ob/ob-luc mice can serve as a model of metabolic stress, similar to human type 2 diabetes using BLI as a surrogate marker for β-cell function.
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Affiliation(s)
- Manishkumar Patel
- Imaging Department, Merck Research Laboratories, Merck and Co., West Point, Pennsylvania, United States of America
- * E-mail:
| | - Alexa Gleason
- Imaging Department, Merck Research Laboratories, Merck and Co., West Point, Pennsylvania, United States of America
| | - Stacey O'Malley
- Imaging Department, Merck Research Laboratories, Merck and Co., West Point, Pennsylvania, United States of America
| | - Brett Connolly
- Imaging Department, Merck Research Laboratories, Merck and Co., West Point, Pennsylvania, United States of America
| | - Donna Suresch
- Imaging Department, Merck Research Laboratories, Merck and Co., West Point, Pennsylvania, United States of America
| | - John Virostko
- Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Neil Phillips
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Shu-An Lin
- Imaging Department, Merck Research Laboratories, Merck and Co., West Point, Pennsylvania, United States of America
| | - Tsing-Bau Chen
- Imaging Department, Merck Research Laboratories, Merck and Co., West Point, Pennsylvania, United States of America
| | - Michael Klimas
- Imaging Department, Merck Research Laboratories, Merck and Co., West Point, Pennsylvania, United States of America
| | - Richard J. Hargreaves
- Imaging Department, Merck Research Laboratories, Merck and Co., West Point, Pennsylvania, United States of America
| | - Cyrille Sur
- Imaging Department, Merck Research Laboratories, Merck and Co., West Point, Pennsylvania, United States of America
| | - David L. Williams
- Imaging Department, Merck Research Laboratories, Merck and Co., West Point, Pennsylvania, United States of America
| | - Alvin C. Powers
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States of America
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University, Nashville, Tennessee, United States of America
- Veterans Affairs Tennessee Valley Healthcare System, Nashville, Tennessee, United States of America
| | - Bohumil Bednar
- Imaging Department, Merck Research Laboratories, Merck and Co., West Point, Pennsylvania, United States of America
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Paradies G, Paradies V, Ruggiero FM, Petrosillo G. Cardiolipin and mitochondrial function in health and disease. Antioxid Redox Signal 2014; 20:1925-53. [PMID: 24094094 DOI: 10.1089/ars.2013.5280] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Cardiolipin (CL) is a unique phospholipid that is almost exclusively localized at the level of the inner mitochondrial membrane (IMM), where it is biosynthesized. This phospholipid is associated with membranes which are designed to generate an electrochemical gradient that is used to produce ATP. Such membranes include the bacterial plasma membrane and IMM. This ubiquitous and intimate association between CL and energy-transducing membranes suggests an important role for CL in mitochondrial bioenergetic processes. CL has been shown to interact with a number of IMM proteins, including the respiratory chain complexes and substrate carriers. Moreover, CL is involved in different stages of the mitochondrial apoptosis process as well as in mitochondrial membrane stability and dynamics. Alterations in CL structure, content, and acyl chain composition have been associated with mitochondrial dysfunction in multiple tissues in several physiopathological conditions and aging. In this review, we provide an overview of the roles of CL in mitochondrial function and bioenergetics in health and disease.
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Affiliation(s)
- Giuseppe Paradies
- 1 Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari , Bari, Italy
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Mega C, Vala H, Rodrigues-Santos P, Oliveira J, Teixeira F, Fernandes R, Reis F, de Lemos ET. Sitagliptin prevents aggravation of endocrine and exocrine pancreatic damage in the Zucker Diabetic Fatty rat - focus on amelioration of metabolic profile and tissue cytoprotective properties. Diabetol Metab Syndr 2014; 6:42. [PMID: 24650557 PMCID: PMC3998187 DOI: 10.1186/1758-5996-6-42] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Accepted: 03/05/2014] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND The purpose of this study was to investigate some of the possible mechanisms underlying the protective effects of a dipeptidyl peptidase IV (DPP-IV) inhibitor, sitagliptin, on pancreatic tissue in an animal model of type 2 diabetes mellitus (T2DM), the Zucker Diabetic Fatty (ZDF) rat, focusing on glycaemic, insulinic and lipidic profiles, as well as, on apoptosis, inflammation, angiogenesis and proliferation mediators. METHODS Male obese diabetic ZDF (fa/fa) rats, aged 20 weeks, were treated with sitagliptin (10 mg/kg bw/day) during 6 weeks and compared to untreated diabetic and lean control littermates. Metabolic data was evaluated at the beginning and at the end of the treatment, including glycaemia, HbA1c, insulinaemia, HOMA-beta and TGs. Endocrine and exocrine pancreas lesions were assessed semiquantitatively by histopathological methods. Pancreas gene (mRNA) and protein expression of mediators of apoptotic machinery, inflammation and angiogenesis/proliferation (Bax, Bcl2, IL-1β, VEGF, PCNA and TRIB3) were analyzed by RT-qPCR and/or by immunohistochemistry. RESULTS Sitagliptin treatment for 6 weeks (between 20 and 26 week-old) was able to significantly (p < 0.001) ameliorate all the metabolic parameters, by preventing the increase in blood glucose and in serum TGs contents (16.54% and 37.63%, respectively, vs untreated), as well as, by preventing the decrease in serum insulin levels and in the functional beta cells capacity accessed via HOMA-beta index (156.28% and 191.74%, respectively, vs untreated). Sitagliptin-treated diabetic rats presented a reduced pancreas Bax/Bcl2 ratio, suggestive of an antiapoptotic effect; in addition, sitagliptin was able to completely reduce (p < 0.001) the pancreas overexpression of IL-1β and TRIB3 found in the untreated diabetic animals; and promoted a significant (p < 0.001) overexpression of VEGF and PCNA. CONCLUSION In this animal model of obese T2DM (the ZDF rat), sitagliptin prevented β-cell dysfunction and evolution of pancreatic damage. The protective effects afforded by this DPP-IV inhibitor may derive from improvement of the metabolic profile (viewed by the amelioration of glucose and TGs levels and of insulin resistance) and from cytoprotective properties, such as antiapoptotic, anti-inflammatory, pro-angiogenic and pro-proliferative.
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Affiliation(s)
- Cristina Mega
- Laboratory of Pharmacology & Experimental Therapeutics, IBILI, Faculty of Medicine, Sub-Unit 1 (Polo III), University of Coimbra, 3000-548 Coimbra, Portugal
- ESAV, Polytechnic Institute of Viseu, Viseu, Portugal
| | - Helena Vala
- ESAV, Polytechnic Institute of Viseu, Viseu, Portugal
- Center for Studies in Education, Technologies and Health (CI&DETS), Polytechnic Institute of Viseu, Viseu, Portugal
| | - Paulo Rodrigues-Santos
- Institute of Immunology, Faculty of Medicine, University of Coimbra, Coimbra, Portugal
- Immunology and Oncology Laboratory, Center for Neurosciences and Cell Biology, Coimbra, Portugal
| | - Jorge Oliveira
- ESAV, Polytechnic Institute of Viseu, Viseu, Portugal
- Center for Studies in Education, Technologies and Health (CI&DETS), Polytechnic Institute of Viseu, Viseu, Portugal
| | - Frederico Teixeira
- Laboratory of Pharmacology & Experimental Therapeutics, IBILI, Faculty of Medicine, Sub-Unit 1 (Polo III), University of Coimbra, 3000-548 Coimbra, Portugal
| | - Rosa Fernandes
- Laboratory of Pharmacology & Experimental Therapeutics, IBILI, Faculty of Medicine, Sub-Unit 1 (Polo III), University of Coimbra, 3000-548 Coimbra, Portugal
| | - Flávio Reis
- Laboratory of Pharmacology & Experimental Therapeutics, IBILI, Faculty of Medicine, Sub-Unit 1 (Polo III), University of Coimbra, 3000-548 Coimbra, Portugal
| | - Edite Teixeira de Lemos
- Laboratory of Pharmacology & Experimental Therapeutics, IBILI, Faculty of Medicine, Sub-Unit 1 (Polo III), University of Coimbra, 3000-548 Coimbra, Portugal
- ESAV, Polytechnic Institute of Viseu, Viseu, Portugal
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Chen Z, Morris DL, Jiang L, Liu Y, Rui L. SH2B1 in β-cells promotes insulin expression and glucose metabolism in mice. Mol Endocrinol 2014; 28:696-705. [PMID: 24645678 DOI: 10.1210/me.2013-1333] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Insulin deficiency drives the progression of both type 1 and type 2 diabetes. Pancreatic β-cell insulin expression and secretion are tightly regulated by nutrients and hormones; however, intracellular signaling proteins that mediate nutrient and hormonal regulation of insulin synthesis and secretion are not fully understood. SH2B1 is an SH2 domain-containing adaptor protein. It enhances the activation of the Janus tyrosine kinase 2 (JAK2)/signal transducer and activator of transcription and the phosphatidylinositol 3-kinase pathways in response to a verity of hormones, growth factors, and cytokines. Here we identify SH2B1 as a new regulator of insulin expression. In rat INS-1 832/13 β-cells, SH2B1 knockdown decreased, whereas SH2B1 overexpression increased, both insulin expression and glucose-stimulated insulin secretion. SH2B1-deficent islets also had reduced insulin expression, insulin content, and glucose-stimulated insulin secretion. Heterozygous deletion of SH2B1 decreased pancreatic insulin content and plasma insulin levels in leptin-deficient ob/ob mice, thus exacerbating hyperglycemia and glucose intolerance. In addition, overexpression of JAK2 increased insulin promoter activity, and SH2B1 enhanced the ability of JAK2 to activate the insulin promoter. Overexpression of SH2B1 also increased the expression of Pdx1 and the recruitment of Pdx1 to the insulin promoter in INS-1 832/13 cells, whereas silencing of SH2B1 had the opposite effects. Consistently, Pdx1 expression was lower in SH2B1-deficient islets. These data suggest that the SH2B1 in β-cells promotes insulin synthesis and secretion at least in part by enhancing activation of JAK2 and/or Pdx1 pathways in response to hormonal and nutritional signals.
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Affiliation(s)
- Zheng Chen
- Department of Molecular and Integrative Physiology (Z.C., D.L.M., L.J., L.R.), University of Michigan Medical School, Ann Arbor, Michigan 48109; Key Laboratory of Nutrition and Metabolism (Y.L.), Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
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Chen Z, Morris DL, Jiang L, Liu Y, Rui L. SH2B1 in β-cells regulates glucose metabolism by promoting β-cell survival and islet expansion. Diabetes 2014; 63:585-95. [PMID: 24150605 PMCID: PMC3900537 DOI: 10.2337/db13-0666] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
IGF-1 and insulin promote β-cell expansion by inhibiting β-cell death and stimulating β-cell proliferation, and the phosphatidylinositol (PI) 3-kinase/Akt pathway mediates insulin and IGF-1 action. Impaired β-cell expansion is a risk factor for type 2 diabetes. Here, we identified SH2B1, which is highly expressed in β-cells, as a novel regulator of β-cell expansion. Silencing of SH2B1 in INS-1 832/13 β-cells attenuated insulin- and IGF-1-stimulated activation of the PI 3-kinase/Akt pathway and increased streptozotocin (STZ)-induced apoptosis; conversely, overexpression of SH2B1 had the opposite effects. Activation of the PI 3-kinase/Akt pathway in β-cells was impaired in pancreas-specific SH2B1 knockout (PKO) mice fed a high-fat diet (HFD). HFD-fed PKO mice also had increased β-cell apoptosis, decreased β-cell proliferation, decreased β-cell mass, decreased pancreatic insulin content, impaired insulin secretion, and exacerbated glucose intolerance. Furthermore, PKO mice were more susceptible to STZ-induced β-cell destruction, insulin deficiency, and hyperglycemia. These data indicate that SH2B1 in β-cells is an important prosurvival and proproliferative protein and promotes compensatory β-cell expansion in the insulin-resistant state and in response to β-cell stress.
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Affiliation(s)
- Zheng Chen
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI
| | - David L. Morris
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI
| | - Lin Jiang
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI
| | - Yong Liu
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Liangyou Rui
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI
- Corresponding author: Liangyou Rui,
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Stamper IJ, Jackson E, Wang X. Phase transitions in pancreatic islet cellular networks and implications for type-1 diabetes. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 89:012719. [PMID: 24580269 PMCID: PMC4172977 DOI: 10.1103/physreve.89.012719] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Indexed: 06/03/2023]
Abstract
In many aspects the onset of a chronic disease resembles a phase transition in a complex dynamic system: Quantitative changes accumulate largely unnoticed until a critical threshold is reached, which causes abrupt qualitative changes of the system. In this study we examine a special case, the onset of type-1 diabetes (T1D), a disease that results from loss of the insulin-producing pancreatic islet β cells. Within each islet, the β cells are electrically coupled to each other via gap-junctional channels. This intercellular coupling enables the β cells to synchronize their insulin release, thereby generating the multiscale temporal rhythms in blood insulin that are critical to maintaining blood glucose homeostasis. Using percolation theory we show how normal islet function is intrinsically linked to network connectivity. In particular, the critical amount of β-cell death at which the islet cellular network loses site percolation is consistent with laboratory and clinical observations of the threshold loss of β cells that causes islet functional failure. In addition, numerical simulations confirm that the islet cellular network needs to be percolated for β cells to synchronize. Furthermore, the interplay between site percolation and bond strength predicts the existence of a transient phase of islet functional recovery after onset of T1D and introduction of treatment, potentially explaining the honeymoon phenomenon. Based on these results, we hypothesize that the onset of T1D may be the result of a phase transition of the islet β-cell network.
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Affiliation(s)
- I. J. Stamper
- Department of Physics, the University of Alabama at Birmingham, Birmingham, Alabama, USA
- The Comprehensive Diabetes Center, the University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Elais Jackson
- Department of Computer and Information Sciences, the University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Xujing Wang
- Department of Physics, the University of Alabama at Birmingham, Birmingham, Alabama, USA
- The Comprehensive Diabetes Center, the University of Alabama at Birmingham, Birmingham, Alabama, USA
- Systems Biology Center, the National Heart, Lung, and Blood Institute, the National Institutes of Health, Bethesda, Maryland, USA
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Ruz M, Carrasco F, Rojas P, Codoceo J, Inostroza J, Basfi-fer K, Valencia A, Vásquez K, Galgani J, Pérez A, López G, Arredondo M, Perez-Bravo F. Zinc as a potential coadjuvant in therapy for type 2 diabetes. Food Nutr Bull 2013; 34:215-21. [PMID: 23964394 DOI: 10.1177/156482651303400210] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND Type 2 diabetes is highly prevalent in populations having high rates of overweight and obesity. It is a chronic condition responsible for long-term severe dysfunction of several organs, including the kidneys, heart, blood vessels, and eyes. Although there are a number of pharmacologic products in the market to treat insulin resistance and impaired insulin secretion--the most prominent features of this disease--interventions directed at preserving the integrity and function of beta-cells in the long term are less available. The use of some nutrients with important cellular protective roles that may lead to a preservation of beta-cells has not been fully tested; among these, zinc may be an interesting candidate. OBJECTIVE To assess the potential of zinc supplementation as coadjuvant to diabetes therapy. METHODS This article reviews the available information on the use of zinc as part of diabetes therapy. RESULTS Cellular and animal models provide information on the insulin mimetic action of zinc, as well as its role as a regulator of oxidative stress, inflammation, apoptosis, and insulin secretion. Zinc supplementation studies in humans are limited, although some positive effects have been reported; mainly, a modest but significant reduction in fasting glucose and a trend to decreased glycated hemoglobin (HbA1c). CONCLUSIONS Zinc supplementation may have beneficial effects on glycemic control. Nevertheless, among the studies considered, the vast majority lasted for 6 months or less, suggesting the importance of conducting long-duration studies given the characteristics of type 2 diabetes as a chronic disease.
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Affiliation(s)
- Manuel Ruz
- Department of Nutrition, Faculty of Medicine, University of Chile, Independencia 1027, Correo 7, Santiago, Chile.
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Zhang Q, Zhu Y, Zhou W, Gao L, Yuan L, Han X. Serotonin receptor 2C and insulin secretion. PLoS One 2013; 8:e54250. [PMID: 23349838 PMCID: PMC3547871 DOI: 10.1371/journal.pone.0054250] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Accepted: 12/10/2012] [Indexed: 12/20/2022] Open
Abstract
Type 2 diabetes mellitus (T2DM) describes a group of metabolic disorders characterized by defects in insulin secretion and insulin sensitivity. Insulin secretion from pancreatic β-cells is an important factor in the etiology of T2DM, though the complex regulation and mechanisms of insulin secretion from β-cells remains to be fully elucidated. High plasma levels of serotonin (5-hydroxytryptamine; 5-HT) have been reported in T2DM patients, though the potential effect on insulin secretion is unclear. However, it is known that the 5-HT receptor 2C (5-HT(2C)R) agonist, mCPP, decreases plasma insulin concentration in mice. As such, we aimed to investigate the expression of the 5-HT(2C)R in pancreatic islets of diabetic mice and the role of 5-HT(2C)R signaling in insulin secretion from pancreatic β-cells. We found that 5-HT(2C)R expression was significantly increased in pancreatic islets of db/db mice. Furthermore, treatment with a 5-HT(2C)R antagonist (SB242084) increased insulin secretion from pancreatic islets isolated from db/db mice in a dose-dependent manner, but had no effect in islets from control mice. The effect of a 5-HT(2C)R agonist (mCPP) and antagonist (SB242084) were further studied in isolated pancreatic islets from mice and Min-6 cells. We found that mCPP significantly inhibited insulin secretion in Min-6 cells and isolated islets in a dose-dependent manner, which could be reversed by SB242084 or RNA interference against 5-HT(2C)R. We also treated Min-6 cells with palmitic acid for 24 h, and found that the expression of 5-HT(2C)R increased in a dose-dependent manner; furthermore, the inhibition of insulin secretion in Min-6 cells induced by palmitic acid could be reversed by SB242084 or RNA interference against 5-HT(2C)R. Taken together, our data suggests that increased expression of 5-HT(2C)R in pancreatic β-cells might inhibit insulin secretion. This unique observation increases our understanding of T2DM and suggests new avenues for potential treatment.
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MESH Headings
- Aminopyridines/pharmacology
- Animals
- Blotting, Western
- Cell Line, Tumor
- Diabetes Mellitus, Type 2/genetics
- Diabetes Mellitus, Type 2/metabolism
- Dose-Response Relationship, Drug
- Gene Expression/drug effects
- Humans
- Indoles/pharmacology
- Insulin/metabolism
- Insulin Secretion
- Insulin-Secreting Cells/drug effects
- Insulin-Secreting Cells/metabolism
- Islets of Langerhans/drug effects
- Islets of Langerhans/metabolism
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Inbred ICR
- Palmitic Acid/pharmacology
- Piperazines/pharmacology
- RNA Interference
- Receptor, Serotonin, 5-HT2C/genetics
- Receptor, Serotonin, 5-HT2C/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Serotonin 5-HT2 Receptor Antagonists/pharmacology
- Serotonin Receptor Agonists/pharmacology
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Affiliation(s)
- Qiang Zhang
- State Key Laboratory of Reproductive Medicine and Key Laboratory of Human Functional Genomics of Jiangsu Province, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Yunxia Zhu
- State Key Laboratory of Reproductive Medicine and Key Laboratory of Human Functional Genomics of Jiangsu Province, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Wenbo Zhou
- State Key Laboratory of Reproductive Medicine and Key Laboratory of Human Functional Genomics of Jiangsu Province, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Lu Gao
- State Key Laboratory of Reproductive Medicine and Key Laboratory of Human Functional Genomics of Jiangsu Province, Nanjing Medical University, Nanjing, Jiangsu, China
| | - Li Yuan
- State Key Laboratory of Reproductive Medicine and Key Laboratory of Human Functional Genomics of Jiangsu Province, Nanjing Medical University, Nanjing, Jiangsu, China
- * E-mail: (XH); (LY)
| | - Xiao Han
- State Key Laboratory of Reproductive Medicine and Key Laboratory of Human Functional Genomics of Jiangsu Province, Nanjing Medical University, Nanjing, Jiangsu, China
- * E-mail: (XH); (LY)
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Rotella F, Cresci B, Monami M, Aletti V, Andreoli V, Ambrosio ML, Ricca V, Dicembrini I, Mannucci E. Are psychopathological features relevant predictors of glucose control in patients with type 2 diabetes? A prospective study. Acta Diabetol 2012; 49 Suppl 1:S179-84. [PMID: 22644473 DOI: 10.1007/s00592-012-0403-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Accepted: 05/08/2012] [Indexed: 12/22/2022]
Abstract
Type 2 diabetes has been associated with an increased prevalence of psychopathology, in comparison with matched non-diabetic controls. However, the cross-sectional design of most studies does not allow causal inferences. The aim of the present study is the exploration of this possible association in patients with type 2 diabetes, in a longitudinal fashion. This prospective observational study was conducted on a consecutive series of 250 type 2 diabetic outpatients and a 1-year follow-up period was performed. At enrollment, a complete medical history was collected and hemoglobin A1c was measured. General psychopathology was assessed using the Symptom Checklist 90-revised and the Eating Disorder Examination Questionnaire. Among the 187 patients available at follow-up, factors associated with unsatisfactory glycemic control at follow-up were baseline hemoglobin A1c, insulin therapy, a longer duration of diabetes, higher scores on the Eating behavior, and Somatization scales. At multivariate analysis, the attainment of hemoglobin A1c ≤ 7 % was associated with baseline hemoglobin A1c (p = 0.01), insulin therapy (p = 0.016), and Eating behavior (p = 0.02), whereas duration of diabetes and Somatization were no longer significant after adjusting for confounders. The results of the present study suggest that clinical features have a much greater impact on attainment of therapeutic goals than psychopathology. However, there are several aspects, such as temperament, motivation, self-efficacy, and well-being, not assessed in the present study, which could be crucial. These areas should be adequately explored for obtaining an overall picture of the psychological determinants of appropriate metabolic control in diabetes.
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Affiliation(s)
- Francesco Rotella
- Diabetes Agency, Careggi Teaching Hospital and University of Florence, Largo Brambilla 3, 50134 Florence, Italy.
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Bensellam M, Laybutt DR, Jonas JC. The molecular mechanisms of pancreatic β-cell glucotoxicity: recent findings and future research directions. Mol Cell Endocrinol 2012; 364:1-27. [PMID: 22885162 DOI: 10.1016/j.mce.2012.08.003] [Citation(s) in RCA: 206] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 07/11/2012] [Accepted: 08/01/2012] [Indexed: 02/06/2023]
Abstract
It is well established that regular physiological stimulation by glucose plays a crucial role in the maintenance of the β-cell differentiated phenotype. In contrast, prolonged or repeated exposure to elevated glucose concentrations both in vitro and in vivo exerts deleterious or toxic effects on the β-cell phenotype, a concept termed as glucotoxicity. Evidence indicates that the latter may greatly contribute to the pathogenesis of type 2 diabetes. Through the activation of several mechanisms and signaling pathways, high glucose levels exert deleterious effects on β-cell function and survival and thereby, lead to the worsening of the disease over time. While the role of high glucose-induced β-cell overstimulation, oxidative stress, excessive Unfolded Protein Response (UPR) activation, and loss of differentiation in the alteration of the β-cell phenotype is well ascertained, at least in vitro and in animal models of type 2 diabetes, the role of other mechanisms such as inflammation, O-GlcNacylation, PKC activation, and amyloidogenesis requires further confirmation. On the other hand, protein glycation is an emerging mechanism that may play an important role in the glucotoxic deterioration of the β-cell phenotype. Finally, our recent evidence suggests that hypoxia may also be a new mechanism of β-cell glucotoxicity. Deciphering these molecular mechanisms of β-cell glucotoxicity is a mandatory first step toward the development of therapeutic strategies to protect β-cells and improve the functional β-cell mass in type 2 diabetes.
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Affiliation(s)
- Mohammed Bensellam
- Université catholique de Louvain, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Brussels, Belgium
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Group VIB Phospholipase A(2) promotes proliferation of INS-1 insulinoma cells and attenuates lipid peroxidation and apoptosis induced by inflammatory cytokines and oxidant agents. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2012; 2012:989372. [PMID: 23213352 PMCID: PMC3503447 DOI: 10.1155/2012/989372] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Accepted: 08/20/2012] [Indexed: 01/09/2023]
Abstract
Group VIB Phospholipase A(2) (iPLA(2)γ) is distributed in membranous organelles in which β-oxidation occurs, that is, mitochondria and peroxisomes, and is expressed by insulin-secreting pancreatic islet β-cells and INS-1 insulinoma cells, which can be injured by inflammatory cytokines, for example, IL-1β and IFN-γ, and by oxidants, for example, streptozotocin (STZ) or t-butyl-hydroperoxide (TBHP), via processes pertinent to mechanisms of β-cell loss in types 1 and 2 diabetes mellitus. We find that incubating INS-1 cells with IL-1β and IFN-γ, with STZ, or with TBHP causes increased expression of iPLA(2)γ mRNA and protein. We prepared INS-1 knockdown (KD) cell lines with reduced iPLA(2)γ expression, and they proliferate more slowly than control INS-1 cells and undergo increased membrane peroxidation in response to cytokines or oxidants. Accumulation of oxidized phospholipid molecular species in STZ-treated INS-1 cells was demonstrated by LC/MS/MS scanning, and the levels in iPLA(2)γ-KD cells exceeded those in control cells. iPLA(2)γ-KD INS-1 cells also exhibited higher levels of apoptosis than control cells when incubated with STZ or with IL-1β and IFN-γ. These findings suggest that iPLA(2)γ promotes β-cell proliferation and that its expression is increased during inflammation or oxidative stress as a mechanism to mitigate membrane injury that may enhance β-cell survival.
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Seed Ahmed M, Kovoor A, Nordman S, Abu Seman N, Gu T, Efendic S, Brismar K, Östenson CG, Gu HF. Increased expression of adenylyl cyclase 3 in pancreatic islets and central nervous system of diabetic Goto-Kakizaki rats: a possible regulatory role in glucose homeostasis. Islets 2012; 4:343-8. [PMID: 23018249 PMCID: PMC3524141 DOI: 10.4161/isl.22283] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Adenylyl cyclase 3 (AC3) is expressed in pancreatic islets of the Goto-Kakizaki (GK) rat, a spontaneous animal model of type 2 diabetes (T2D), and also exerts genetic effects on the regulation of body weight in man. In addition to pancreatic islets, the central nervous system (CNS) plays an important role in the pathogenesis of T2D and obesity by regulating feeding behavior, body weight and glucose metabolism. In the present study, we have investigated AC3 expression in pancreatic islets, striatum and hypothalamus of GK rats to evaluate its role in the regulation of glucose homeostasis. GK and Wistar rats at the age of 2.5 mo were used. A group of GK rats were implanted with sustained insulin release chips for 15 d. Plasma glucose and serum insulin levels were measured. AC3 gene expression levels in pancreatic islets, striatum and hypothalamus were determined by using real-time RT-PCR. Results indicated that plasma glucose levels in Wistar rats were found to be similar to insulin-treated GK rats, and significantly lower compared with non-treated GK rats. AC3 expression levels in pancreatic islets, striatum and hypothalamus of GK rats were higher compared with Wistar rats, while the levels were intermediate in insulin-treated GK rats. The AC3 expression display patterns between pancreatic islets and striatum-hypothalamus were similar. The present study thus provides the first evidence that AC3 is overexpressed in the regions of striatum and hypothalamus of brain, and similarly in pancreatic islets of GK rats suggesting that AC3 plays a role in regulation of glucose homeostasis via CNS and insulin secretion.
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Affiliation(s)
- Mohammed Seed Ahmed
- Department of Molecular Medicine and Surgery; Karolinska Institutet; Karolinska University Hospital; Stockholm, Sweden
| | - Abraham Kovoor
- Department of Biomedical and Pharmaceutical Sciences; University of Rhode Island; Kingston, RI USA
| | - Sofia Nordman
- Department of Molecular Medicine and Surgery; Karolinska Institutet; Karolinska University Hospital; Stockholm, Sweden
| | - Norhashimah Abu Seman
- Department of Molecular Medicine and Surgery; Karolinska Institutet; Karolinska University Hospital; Stockholm, Sweden
| | - Tianwei Gu
- Department of Molecular Medicine and Surgery; Karolinska Institutet; Karolinska University Hospital; Stockholm, Sweden
| | - Suad Efendic
- Department of Molecular Medicine and Surgery; Karolinska Institutet; Karolinska University Hospital; Stockholm, Sweden
| | - Kerstin Brismar
- Department of Molecular Medicine and Surgery; Karolinska Institutet; Karolinska University Hospital; Stockholm, Sweden
| | - Claes-Göran Östenson
- Department of Molecular Medicine and Surgery; Karolinska Institutet; Karolinska University Hospital; Stockholm, Sweden
| | - Harvest F. Gu
- Department of Molecular Medicine and Surgery; Karolinska Institutet; Karolinska University Hospital; Stockholm, Sweden
- Correspondence to: Harvest F. Gu,
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Shen H, Shao M, Cho KW, Wang S, Chen Z, Sheng L, Wang T, Liu Y, Rui L. Herbal constituent sequoyitol improves hyperglycemia and glucose intolerance by targeting hepatocytes, adipocytes, and β-cells. Am J Physiol Endocrinol Metab 2012; 302:E932-40. [PMID: 22297305 PMCID: PMC3330724 DOI: 10.1152/ajpendo.00479.2011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The prevalence of insulin resistance and type 2 diabetes increases rapidly; however, treatments are limited. Various herbal extracts have been reported to reduce blood glucose in animals with either genetic or dietary type 2 diabetes; however, plant extracts are extremely complex, and leading compounds remain largely unknown. Here we show that 5-O-methyl-myo-inositol (also called sequoyitol), a herbal constituent, exerts antidiabetic effects in mice. Sequoyitol was chronically administrated into ob/ob mice either orally or subcutaneously. Both oral and subcutaneous administrations of sequoyitol decreased blood glucose, improved glucose intolerance, and enhanced insulin signaling in ob/ob mice. Sequoyitol directly enhanced insulin signaling, including phosphorylation of insulin receptor substrate-1 and Akt, in both HepG2 cells (derived from human hepatocytes) and 3T3-L1 adipocytes. In agreement, sequoyitol increased the ability of insulin to suppress glucose production in primary hepatocytes and to stimulate glucose uptake into primary adipocytes. Furthermore, sequoyitol improved insulin signaling in INS-1 cells (a rat β-cell line) and protected INS-1 cells from streptozotocin- or H₂O₂-induced injury. In mice with streptozotocin-induced β-cell deficiency, sequoyitol treatments increased plasma insulin levels and decreased hyperglycemia and glucose intolerance. These results indicate that sequoyitol, a natural, water-soluble small molecule, ameliorates hyperglycemia and glucose intolerance by increasing both insulin sensitivity and insulin secretion. Sequoyitol appears to directly target hepatocytes, adipocytes, and β-cells. Therefore, sequoyitol may serve as a new oral diabetes medication.
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Affiliation(s)
- Hong Shen
- Dept. of Molecular & Integrative Physiology, Univ. of Michigan Medical School, Ann Arbor, MI 48109-0622, USA
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Calegari VC, Abrantes JL, Silveira LR, Paula FM, Costa JM, Rafacho A, Velloso LA, Carneiro EM, Bosqueiro JR, Boschero AC, Zoppi CC. Endurance training stimulates growth and survival pathways and the redox balance in rat pancreatic islets. J Appl Physiol (1985) 2012; 112:711-8. [DOI: 10.1152/japplphysiol.00318.2011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Endurance training has been shown to increase pancreatic β-cell function and mass. However, whether exercise modulates β-cell growth and survival pathways signaling is not completely understood. This study investigated the effects of exercise on growth and apoptotic markers levels in rat pancreatic islets. Male Wistar rats were randomly assigned to 8-wk endurance training or to a sedentary control group. After that, pancreatic islets were isolated; gene expression and the total content and phosphorylation of several proteins related to growth and apoptotic pathways as well as the main antioxidant enzymes were determined by real-time polymerase chain reaction and Western blot analysis, respectively. Reactive oxygen species (ROS) production was measured by fluorescence. Endurance training increased the time to reach fatigue by 50%. Endurance training resulted in increased protein phosphorylation content of AKT (75%), AKT substrate (AS160; 100%), mTOR (60%), p70s6k (90%), and ERK1/2 (50%), compared with islets from control group. Catalase protein content was 50% higher, whereas ROS production was 49 and 77% lower in islets from trained rats under basal and stimulating glucose conditions, respectively. Bcl-2 mRNA and protein levels increased by 46 and 100%, respectively. Bax and cleaved caspase-3 protein contents were reduced by 25 and 50% in islets from trained rats, respectively. In conclusion, these results demonstrate that endurance training favors the β-cell growth and survival by activating AKT and ERK1/2 pathways, enhancing antioxidant capacity, and reducing ROS production and apoptotic proteins content.
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Affiliation(s)
- Vivian C. Calegari
- Department of Anatomy, Cellular Biology and Physiology and Biophysics, Institute of Biology and
| | - Julia L. Abrantes
- Department of Anatomy, Cellular Biology and Physiology and Biophysics, Institute of Biology and
| | - Leonardo R. Silveira
- School of Physical Education and Sports, Faculty of Medicine, Department of Biochemistry and Immunology, University of Sao Paulo (USP), Ribeirão Preto, Sao Paulo
| | - Flavia M. Paula
- Department of Anatomy, Cellular Biology and Physiology and Biophysics, Institute of Biology and
| | - José Maria Costa
- Department of Anatomy, Cellular Biology and Physiology and Biophysics, Institute of Biology and
| | - Alex Rafacho
- Department of Anatomy, Cellular Biology and Physiology and Biophysics, Institute of Biology and
- Department of Physiological Sciences, Center of Biological Sciences, Federal University of Santa Catarina (UFSC), Florianopolis, Santa Catarina; and
| | - Lício A. Velloso
- Laboratory of Cell Signaling, State University of Campinas (UNICAMP), Campinas
| | - Everardo M. Carneiro
- Department of Anatomy, Cellular Biology and Physiology and Biophysics, Institute of Biology and
| | - Jose R. Bosqueiro
- Department of Physical Education, School of Science, Sao Paulo State University, UNESP, Bauru, Sao Paulo, Brazil
| | - Antonio C. Boschero
- Department of Anatomy, Cellular Biology and Physiology and Biophysics, Institute of Biology and
| | - Claudio C. Zoppi
- Department of Anatomy, Cellular Biology and Physiology and Biophysics, Institute of Biology and
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Ma ZA. The role of peroxidation of mitochondrial membrane phospholipids in pancreatic β -cell failure. Curr Diabetes Rev 2012; 8:69-75. [PMID: 22414059 PMCID: PMC4884441 DOI: 10.2174/157339912798829232] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Revised: 08/15/2011] [Accepted: 09/13/2011] [Indexed: 12/28/2022]
Abstract
Type 2 diabetes (T2D) is characterized by peripheral insulin resistance and pancreatic islet β-cell failure. Accumulating evidence indicates that mitochondrial dysfunction is a central contributor to β-cell failure in the pathogenesis of T2D. This review focuses on mechanisms whereby reactive oxygen species (ROS) produced by β-cell in response to metabolic stress affect mitochondrial structure and function and lead to β-cell failure. Specifically, ROS oxidize mitochondrial membrane phospholipids such as cardiolipin, which impairs membrane integrity and leads to cytochrome c release and apoptosis. In addition, ROS activate UCP2 via peroxidation of the mitochondrial membrane phospholipids, which results in proton leak leading to reduced ATP synthesis and content in β-cells - critical parameters in the regulation of glucose-stimulated insulin secretion. Group VIA Phospholipase A2 (iPLA2β) appears to be a component of a mechanism for repairing mitochondrial phospholipids that contain oxidized fatty acid substituents, and genetic or acquired iPLA2β-deficiency increases β-cell mitochondrial susceptibility to injury from ROS and predisposes to development of T2D. Interventions that attenuate the adverse effects of ROS on β-cell mitochondrial phospholipids may prevent or retard the development of T2D.
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Affiliation(s)
- Zhongmin A Ma
- Division of Experimental Diabetes and Aging, Department of Geriatrics and Palliative Medicine, Mount Sinai School of Medicine, New York, NY 10029, USA.
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Kilimnik G, Zhao B, Jo J, Periwal V, Witkowski P, Misawa R, Hara M. Altered islet composition and disproportionate loss of large islets in patients with type 2 diabetes. PLoS One 2011; 6:e27445. [PMID: 22102895 PMCID: PMC3216964 DOI: 10.1371/journal.pone.0027445] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Accepted: 10/17/2011] [Indexed: 01/09/2023] Open
Abstract
Human islets exhibit distinct islet architecture with intermingled alpha- and beta-cells particularly in large islets. In this study, we quantitatively examined pathological changes of the pancreas in patients with type 2 diabetes (T2D). Specifically, we tested a hypothesis that changes in endocrine cell mass and composition are islet-size dependent. A large-scale analysis of cadaveric pancreatic sections from T2D patients (n = 12) and non-diabetic subjects (n = 14) was carried out combined with semi-automated analysis to quantify changes in islet architecture. The method provided the representative islet distribution in the whole pancreas section that allowed us to examine details of endocrine cell composition in individual islets. We observed a preferential loss of large islets (>60 µm in diameter) in T2D patients compared to non-diabetic subjects. Analysis of islet cell composition revealed that the beta-cell fraction in large islets was decreased in T2D patients. This change was accompanied by a reciprocal increase in alpha-cell fraction, however total alpha-cell area was decreased along with beta-cells in T2D. Delta-cell fraction and area remained unchanged. The computer-assisted quantification of morphological changes in islet structure minimizes sampling bias. Significant beta-cell loss was observed in large islets in T2D, in which alpha-cell ratio reciprocally increased. However, there was no alpha-cell expansion and the total alpha-cell area was also decreased. Changes in islet architecture were marked in large islets. Our method is widely applicable to various specimens using standard immunohistochemical analysis that may be particularly useful to study large animals including humans where large organ size precludes manual quantitation of organ morphology.
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Affiliation(s)
- German Kilimnik
- Department of Medicine, The University of Chicago, Chicago, Illinois, United States of America
| | - Billy Zhao
- Department of Medicine, The University of Chicago, Chicago, Illinois, United States of America
| | - Junghyo Jo
- Laboratory of Biological Modeling, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Vipul Periwal
- Laboratory of Biological Modeling, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Piotr Witkowski
- Department of Surgery, The University of Chicago, Chicago, Illinois, United States of America
| | - Ryosuke Misawa
- Department of Surgery, The University of Chicago, Chicago, Illinois, United States of America
| | - Manami Hara
- Department of Medicine, The University of Chicago, Chicago, Illinois, United States of America
- * E-mail:
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Mitochondrial dysfunction and β-cell failure in type 2 diabetes mellitus. EXPERIMENTAL DIABETES RESEARCH 2011; 2012:703538. [PMID: 22110477 PMCID: PMC3216264 DOI: 10.1155/2012/703538] [Citation(s) in RCA: 146] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Accepted: 09/03/2011] [Indexed: 01/09/2023]
Abstract
Type 2 diabetes mellitus (T2DM) is the most common human endocrine disease and is characterized by peripheral insulin resistance and pancreatic islet β-cell failure. Accumulating evidence indicates that mitochondrial dysfunction is a central contributor to β-cell failure in the evolution of T2DM. As reviewed elsewhere, reactive oxygen species (ROS) produced by β-cell mitochondria as a result of metabolic stress activate several stress-response pathways. This paper focuses on mechanisms whereby ROS affect mitochondrial structure and function and lead to β-cell failure. ROS activate UCP2, which results in proton leak across the mitochondrial inner membrane, and this leads to reduced β-cell ATP synthesis and content, which is a critical parameter in regulating glucose-stimulated insulin secretion. In addition, ROS oxidize polyunsaturated fatty acids in mitochondrial cardiolipin and other phospholipids, and this impairs membrane integrity and leads to cytochrome c release into cytosol and apoptosis. Group VIA phospholipase A2 (iPLA2β) appears to be a component of a mechanism for repairing mitochondrial phospholipids that contain oxidized fatty acid substituents, and genetic or acquired iPLA2β-deficiency increases β-cell mitochondrial susceptibility to injury from ROS and predisposes to developing T2DM. Interventions that attenuate ROS effects on β-cell mitochondrial phospholipids might prevent or retard development of T2DM.
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Macrophage migration inhibitory factor deficiency protects pancreatic islets from palmitic acid-induced apoptosis. Immunol Cell Biol 2011; 90:688-98. [PMID: 22064706 DOI: 10.1038/icb.2011.89] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
As a result of chronic exposure to high levels of free fatty acids, glucose and inflammatory mediators β-cell apoptosis occurs at the end stage of obesity-associated type 2 diabetes (T2D). One potentially deleterious molecule for β-cell function associated with T2D and obesity in humans is macrophage migration inhibitory factor (MIF). Therefore, the aim of this study was to explore MIF expression in vivo during development of obesity and insulin resistance in high-fat diet (HFD)-fed C57BL/6 mice and whether MIF inhibition could affect β-cell apoptosis and dysfunction induced by palmitic acid (PA) in vitro. Indeed, increase in systemic and locally produced MIF correlated well with the weight gain, triglyceride upregulation, glucose intolerance and insulin resistance, which developed in HFD-fed mice. In in vitro settings PA dose-dependently induced MIF secretion before apoptosis development in islets. Further, mif gene deletion, mRNA silencing or protein inhibition rescued β-cells from PA-induced apoptosis as measured by MTT assay and histone-DNA enzyme linked immuno sorbent assay. Protection from induced apoptosis was mediated by altered activation of caspase pathway and correlated with changes in the level of Bcl-2 family members. Further, MIF inhibition conveyed a significant resistance to PA-induced downregulation of insulin and PDX-1 expression and ATP content. However, β-cell function was not entirely preserved in the absence of MIF judging by low glucose oxidation and depolarized mitochondrial membrane. In conclusion, the observed considerable preservation of β-cells from nutrient-induced apoptosis might implicate MIF as a potential therapeutic target in the later stage of obesity-associated T2D.
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Smith GC, Konycheva G, Dziadek MA, Ravelich SR, Patel S, Reddy S, Breier BH, Vickers MH, Owens JA, Ferguson LR. Pre- and postnatal methyl deficiency in the rat differentially alters glucose homeostasis. JOURNAL OF NUTRIGENETICS AND NUTRIGENOMICS 2011; 4:175-91. [PMID: 21860247 DOI: 10.1159/000330227] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Accepted: 06/09/2011] [Indexed: 01/18/2023]
Abstract
BACKGROUND/AIMS Early-life methyl-donor deficiency is implicated in growth restriction and later-life development of type 2 diabetes mellitus. We ascertained whether dietary methyl-donor deficiency in the mother during pregnancy or during postweaning growth in the rat would impair glucose homeostasis, insulin secretion and pancreatic endocrine development in young adults. METHODS Effects of maternal methyl deficiency (90% deficiency in methionine, folate and choline) were compared with those of postweaning methyl deficiency and with control diets for effects on growth, impaired glucose tolerance, insulin secretion and pancreas development in offspring. Studies focussed on male offspring, which have been shown more susceptible to early-life influences on later disease development. RESULTS Prenatal methyl deficiency delayed delivery, restricted birthweight by 22%, reduced litter size by 33% and increased offspring mortality to 23% shortly after birth. It reduced relative endocrine pancreatic mass in adult male offspring to 46% of endocrine mass in controls, but only mildly impaired their glucose tolerance and insulin secretion. In contrast, postweaning methyl deficiency restricted growth of male rats and reduced relative pancreatic endocrine mass (-40%), but improved their glucose tolerance, despite decreased insulin secretion. CONCLUSION It is clear that the global undernutrition (UN) during pregnancy in rodents alters glucose metabolism in adult offspring. It has been hypothesised that alterations in epigenetic mechanisms may underlie this phenotype. However, removing all methyl donors during pregnancy, which are essential for epigenetic processes in development, did not cause any alteration in glucose metabolism in offspring as seen in the global UN model.
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Affiliation(s)
- Greg C Smith
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
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Abstract
The increasing prevalence, variable pathogenesis, progressive natural history, and complications of type 2 diabetes emphasise the urgent need for new treatment strategies. Longacting (eg, once weekly) agonists of the glucagon-like-peptide-1 receptor are advanced in development, and they improve prandial insulin secretion, reduce excess glucagon production, and promote satiety. Trials of inhibitors of dipeptidyl peptidase 4, which enhance the effect of endogenous incretin hormones, are also nearing completion. Novel approaches to glycaemic regulation include use of inhibitors of the sodium-glucose cotransporter 2, which increase renal glucose elimination, and inhibitors of 11β-hydroxysteroid dehydrogenase 1, which reduce the glucocorticoid effects in liver and fat. Insulin-releasing glucokinase activators and pancreatic-G-protein-coupled fatty-acid-receptor agonists, glucagon-receptor antagonists, and metabolic inhibitors of hepatic glucose output are being assessed. Early proof of principle has been shown for compounds that enhance and partly mimic insulin action and replicate some effects of bariatric surgery.
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Affiliation(s)
- Abd A Tahrani
- Centre of Endocrinology, Diabetes and Metabolism, University of Birmingham, Birmingham, UK
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