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Guzmán TJ, Klöpper N, Gurrola-Díaz CM, Düfer M. Inhibition of mTOR prevents glucotoxicity-mediated increase of SA-beta-gal, p16 INK4a, and insulin hypersecretion, without restoring electrical features of mouse pancreatic islets. Biogerontology 2024; 25:819-836. [PMID: 38748336 PMCID: PMC11374829 DOI: 10.1007/s10522-024-10107-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2024] [Accepted: 04/16/2024] [Indexed: 09/05/2024]
Abstract
An over-activation of the mechanistic target of rapamycin (mTOR) pathway promotes senescence and age-related diseases like type 2 diabetes. Besides, the regenerative potential of pancreatic islets deteriorates with aging. Nevertheless, the role of mTOR on senescence promoted by metabolic stress in islet cells as well as its relevance for electrophysiological aspects is not yet known. Here, we investigated whether parameters suggested to be indicative for senescence are induced in vitro in mouse islet cells by glucotoxicity and if mTOR inhibition plays a protective role against this. Islet cells exhibit a significant increase (~ 76%) in senescence-associated beta-galactosidase (SA-beta-gal) activity after exposure to glucotoxicity for 72 h. Glucotoxicity does not markedly influence p16INK4a protein within 72 h, but p16INK4a levels increase significantly after a 7-days incubation period. mTOR inhibition with a low rapamycin concentration (1 nM) entirely prevents the glucotoxicity-mediated increase of SA-beta-gal and p16INK4a. At the functional level, reactive oxygen species, calcium homeostasis, and electrical activity are disturbed by glucotoxicity, and rapamycin fails to prevent this. In contrast, rapamycin significantly attenuates the insulin hypersecretion promoted by glucotoxicity by modifying the mRNA levels of Vamp2 and Snap25 genes, related to insulin exocytosis. Our data indicate an influence of glucotoxicity on pancreatic islet-cell senescence and a reduction of the senescence markers by mTOR inhibition, which is relevant to preserve the regenerative potential of the islets. Decreasing the influence of mTOR on islet cells exposed to glucotoxicity attenuates insulin hypersecretion, but is not sufficient to prevent electrophysiological disturbances, indicating the involvement of mTOR-independent mechanisms.
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Affiliation(s)
- Tereso J Guzmán
- Department of Pharmacology, Institute of Pharmaceutical and Medicinal Chemistry, University of Münster, Corrensstraße 48, 48149, Münster, Germany.
- Departamento de Biología Molecular y Genómica, Universidad de Guadalajara, Instituto de Investigación en Enfermedades Crónico-Degenerativas, Centro Universitario de Ciencias de la Salud, 44340, Guadalajara, Jalisco, México.
| | - Nina Klöpper
- Department of Pharmacology, Institute of Pharmaceutical and Medicinal Chemistry, University of Münster, Corrensstraße 48, 48149, Münster, Germany
| | - Carmen M Gurrola-Díaz
- Departamento de Biología Molecular y Genómica, Universidad de Guadalajara, Instituto de Investigación en Enfermedades Crónico-Degenerativas, Centro Universitario de Ciencias de la Salud, 44340, Guadalajara, Jalisco, México
| | - Martina Düfer
- Department of Pharmacology, Institute of Pharmaceutical and Medicinal Chemistry, University of Münster, Corrensstraße 48, 48149, Münster, Germany.
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2
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Nie Y, Zhang Y, Liu S, Xu Z, Xia C, Du L, Yin X, Wang J. Downregulation of Sirt3 contributes to β-cell dedifferentiation via FoxO1 in type 2 diabetic mellitus. Acta Diabetol 2024; 61:485-494. [PMID: 38150004 DOI: 10.1007/s00592-023-02221-w] [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: 05/29/2023] [Accepted: 11/29/2023] [Indexed: 12/28/2023]
Abstract
AIMS FoxO1 is an important factor in the β-cell differentiation in type 2 diabetes mellitus (T2DM). Sirt3 is found to be involved in FoxO1 function. This study investigated the role of Sirt3 in the β-cell dedifferentiation and its mechanism. METHODS Twelve-week-old db/db mice and INS1 cells transfected with Sirt3-specific short hairpin RNA (shSirt3) were used to evaluate the dedifferentiation of β-cell. Insulin levels were measured by enzyme linked immunosorbent assay. The proteins of Sirt3, T-FoxO1, Ac-FoxO1 and differentiation indexes such as NGN3, OCT4, MAFA were determined by western blot or immunofluorescence staining. The combination of Sirt3 and FoxO1 was determined by the co-immunoprecipitation assay. The transcriptional activity of FoxO1 was detected by dual luciferase reporter assay. RESULTS Both the in vivo and in vitro results showed that Sirt3 was decreased along with β-cell dedifferentiation and decreased function of insulin secretion under high glucose conditions. When Sirt3 was knocked down in INS1 cells, increased β-cell dedifferentiation and lowered insulin secretion were observed. This effect was closely related to the amount loss and the decreased deacetylation of FoxO1, which resulted in a reduction in transcriptional activity. CONCLUSION Downregulation of Sirt3 contributes to β-cell dedifferentiation in high glucose via FoxO1. Intervention of Sirt3 may be an effective approach to prevent β-cell failure in T2DM.
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Affiliation(s)
- Yaxing Nie
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, Xuzhou, 221002, Jiangsu, China
| | - Yunye Zhang
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, Xuzhou, 221002, Jiangsu, China
| | - Shuqing Liu
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, Xuzhou, 221002, Jiangsu, China
| | - Zhi Xu
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, Xuzhou, 221002, Jiangsu, China
| | - Chunya Xia
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, Xuzhou, 221002, Jiangsu, China
| | - Lei Du
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, Xuzhou, 221002, Jiangsu, China
| | - Xiaoxing Yin
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, Xuzhou, 221002, Jiangsu, China
| | - Jianyun Wang
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, Xuzhou Medical University, Xuzhou, 221002, Jiangsu, China.
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Del Carpio E, Serrano ML, Hernández L, Madden W, Lubes V, Landaeta VR, Rodríguez-Lugo RE, Lubes G, Stern A, Ciangherotti C, Jiménez L. Speciation study and biological activity of copper (II) complexes with picolinic and 6-methylpicolinic acid with different components of blood serum of low molecular mass in KNO3 1.0 mol·L−1 at 25 °C. Polyhedron 2022. [DOI: 10.1016/j.poly.2021.115562] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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4
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Nahle A, Joseph YD, Pereira S, Mori Y, Poon F, Ghadieh HE, Ivovic A, Desai T, Ghanem SS, Asalla S, Muturi HT, Jentz EM, Joseph JW, Najjar SM, Giacca A. Nicotinamide Mononucleotide Prevents Free Fatty Acid-Induced Reduction in Glucose Tolerance by Decreasing Insulin Clearance. Int J Mol Sci 2021; 22:ijms222413224. [PMID: 34948019 PMCID: PMC8709165 DOI: 10.3390/ijms222413224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 12/02/2021] [Accepted: 12/03/2021] [Indexed: 11/24/2022] Open
Abstract
The NAD-dependent deacetylase SIRT1 improves β cell function. Accordingly, nicotinamide mononucleotide (NMN), the product of the rate-limiting step in NAD synthesis, prevents β cell dysfunction and glucose intolerance in mice fed a high-fat diet. The current study was performed to assess the effects of NMN on β cell dysfunction and glucose intolerance that are caused specifically by increased circulating free fatty acids (FFAs). NMN was intravenously infused, with or without oleate, in C57BL/6J mice over a 48-h-period to elevate intracellular NAD levels and consequently increase SIRT1 activity. Administration of NMN in the context of elevated plasma FFA levels considerably improved glucose tolerance. This was due not only to partial protection from FFA-induced β cell dysfunction but also, unexpectedly, to a significant decrease in insulin clearance. However, in conditions of normal FFA levels, NMN impaired glucose tolerance due to decreased β cell function. The presence of this dual action of NMN suggests caution in its proposed therapeutic use in humans.
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Affiliation(s)
- Ashraf Nahle
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada; (A.N.); (Y.D.J.); (S.P.); (Y.M.); (F.P.); (A.I.); (T.D.)
| | - Yemisi Deborah Joseph
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada; (A.N.); (Y.D.J.); (S.P.); (Y.M.); (F.P.); (A.I.); (T.D.)
| | - Sandra Pereira
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada; (A.N.); (Y.D.J.); (S.P.); (Y.M.); (F.P.); (A.I.); (T.D.)
| | - Yusaku Mori
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada; (A.N.); (Y.D.J.); (S.P.); (Y.M.); (F.P.); (A.I.); (T.D.)
- Division of Diabetes, Metabolism and Endocrinology, Showa University School of Medicine, Shinagawa, Tokyo 142-0064, Japan
| | - Frankie Poon
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada; (A.N.); (Y.D.J.); (S.P.); (Y.M.); (F.P.); (A.I.); (T.D.)
| | - Hilda E. Ghadieh
- Center for Diabetes and Endocrine Research, College of Medicine and Life Sciences, University of Toledo, Toledo, OH 43606, USA; (H.E.G.); (S.S.G.); (S.M.N.)
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH 45701, USA; (S.A.); (H.T.M.)
| | - Aleksandar Ivovic
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada; (A.N.); (Y.D.J.); (S.P.); (Y.M.); (F.P.); (A.I.); (T.D.)
| | - Tejas Desai
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada; (A.N.); (Y.D.J.); (S.P.); (Y.M.); (F.P.); (A.I.); (T.D.)
| | - Simona S. Ghanem
- Center for Diabetes and Endocrine Research, College of Medicine and Life Sciences, University of Toledo, Toledo, OH 43606, USA; (H.E.G.); (S.S.G.); (S.M.N.)
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH 45701, USA; (S.A.); (H.T.M.)
| | - Suman Asalla
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH 45701, USA; (S.A.); (H.T.M.)
| | - Harrison T. Muturi
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH 45701, USA; (S.A.); (H.T.M.)
| | - Emelien M. Jentz
- School of Pharmacy, University of Waterloo, Kitchener, ON N2G 1C5, Canada; (E.M.J.); (J.W.J.)
| | - Jamie W. Joseph
- School of Pharmacy, University of Waterloo, Kitchener, ON N2G 1C5, Canada; (E.M.J.); (J.W.J.)
| | - Sonia M. Najjar
- Center for Diabetes and Endocrine Research, College of Medicine and Life Sciences, University of Toledo, Toledo, OH 43606, USA; (H.E.G.); (S.S.G.); (S.M.N.)
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH 45701, USA; (S.A.); (H.T.M.)
- Diabetes Institute, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH 45701, USA
| | - Adria Giacca
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada; (A.N.); (Y.D.J.); (S.P.); (Y.M.); (F.P.); (A.I.); (T.D.)
- Banting and Best Diabetes Centre, University of Toronto, Toronto, ON M5G 2C4, Canada
- Department of Medicine, University of Toronto, Toronto, ON M5S 1A1, Canada
- Institute of Medical Science, University of Toronto, Toronto, ON M5S 1A8, Canada
- Correspondence:
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5
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Szlapinski SK, Hill DJ. Metabolic Adaptations to Pregnancy in Healthy and Gestational Diabetic Pregnancies: The Pancreas - Placenta Axis. Curr Vasc Pharmacol 2021; 19:141-153. [PMID: 32196450 DOI: 10.2174/1570161118666200320111209] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 02/20/2020] [Accepted: 03/01/2020] [Indexed: 12/16/2022]
Abstract
Normal pregnancy is associated with increased insulin resistance as a metabolic adaptation to the nutritional demands of the placenta and fetus, and this is amplified in obese mothers. Insulin resistance is normally compensated for by an adaptive increase in pancreatic β-cell mass together with enhanced glucose-stimulated insulin release. Placentally-derived hormones and growth factors are central to the altered pancreatic morphology and function. A failure of β-cells to undergo adaptive change after the first trimester has been linked with gestational diabetes. In the pregnant mouse, an increase in β-cell replication contributes to a 2-3-fold increase in mass peaking in late gestation, depending on the proliferation of existing β-cells, the differentiation of resident progenitor β-cells, or islet cell transdifferentiation. Using mouse models and human studies placenta- and islet of Langerhans-derived molecules have been identified that are likely to contribute to the metabolic adaptations to pregnancy and whose physiology is altered in the obese, glucose-intolerant mother. Maternal obesity during pregnancy can create a pro-inflammatory environment that can disrupt the response of the β-cells to the endocrine signals of pregnancy and limit the adaptive changes in β-cell mass and function, resulting in an increased risk of gestational diabetes.
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Affiliation(s)
- Sandra K Szlapinski
- Lawson Health Research Institute, St. Joseph's Health Care, 268 Grosvenor Street, London, Ontario N6A 4V2, Canada
| | - David J Hill
- Lawson Health Research Institute, St. Joseph's Health Care, 268 Grosvenor Street, London, Ontario N6A 4V2, Canada
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Utzschneider KM, Johnson TN, Breymeyer KL, Bettcher L, Raftery D, Newton KM, Neuhouser ML. Small changes in glucose variability induced by low and high glycemic index diets are not associated with changes in β-cell function in adults with pre-diabetes. J Diabetes Complications 2020; 34:107586. [PMID: 32546421 PMCID: PMC7583355 DOI: 10.1016/j.jdiacomp.2020.107586] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 03/31/2020] [Accepted: 03/31/2020] [Indexed: 01/11/2023]
Abstract
Oscillating glucose levels can increase oxidative stress and may contribute to β-cell dysfunction. We tested the hypothesis that increased glycemic variability contributes to β-cell dysfunction by experimentally altering glucose variability with controlled diets varying in glycemic index (GI). Fifty-two adults with prediabetes received a 2-week moderate GI (GI = 55-58) control diet followed by randomization to a four-week low GI (LGI: GI < 35) or high GI (HGI HI > 70) diet. Those on the HGI diet were randomized to placebo or the antioxidant N-acetylcysteine (NAC). Participants underwent blinded CGMS, fasting oxidative stress markers and an intravenous glucose tolerance test to estimate β-cell function (disposition index: DI). On the control diet, DI was inversely correlated with SD glucose (r = -0.314, p = 0.03), but neither DI nor glucose variability were associated with oxidative stress markers. The LGI diet decreased SD glucose (Control 0.96 ± 0.08 vs. LGI 0.79 ± 0.06, p = 0.02) while the HGI diet increased it (Control 0.88 ± 0.06 vs. HGI 1.06 ± 0.07, p = 0.03). Neither DI nor oxidative stress markers changed after the LGI or HGI diets. NAC had no effect on DI, glucose variability or oxidative stress markers. We conclude small changes in glucose variability induced by dietary GI in adults with pre-diabetes are unlikely to contribute to β-cell dysfunction.
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Affiliation(s)
- Kristina M Utzschneider
- Research and Development, Department of Medicine, 1660 S Columbian Way (151), VA Puget Sound Health Care System, Seattle, WA 98108, USA; Division of Metabolism, Endocrinology and Nutrition, University of Washington, 1959 NE Pacific Street, Seattle, WA 98195-6426, USA.
| | - Tonya N Johnson
- Research and Development, Department of Medicine, 1660 S Columbian Way (151), VA Puget Sound Health Care System, Seattle, WA 98108, USA; Seattle Institute for BIomedical and Clinical Research, Seattle, WA, USA
| | - Kara L Breymeyer
- Public Health Sciences Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave N, Seattle, WA 98109, USA
| | - Lisa Bettcher
- Department of Anesthesiology and Pain Medicine, University of Washington, 1959 NE Pacific Street, Seattle, WA 98195-6426, USA.
| | - Daniel Raftery
- Department of Anesthesiology and Pain Medicine, University of Washington, 1959 NE Pacific Street, Seattle, WA 98195-6426, USA.
| | - Katherine M Newton
- Kaiser Permanente Health Research Institute, 1730 Minor Ave, Seattle, WA 98101, USA.
| | - Marian L Neuhouser
- Public Health Sciences Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Ave N, Seattle, WA 98109, USA.
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7
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Role of c-Jun N-terminal Kinase (JNK) in Obesity and Type 2 Diabetes. Cells 2020; 9:cells9030706. [PMID: 32183037 PMCID: PMC7140703 DOI: 10.3390/cells9030706] [Citation(s) in RCA: 105] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 02/16/2020] [Accepted: 03/11/2020] [Indexed: 12/13/2022] Open
Abstract
Obesity has been described as a global epidemic and is a low-grade chronic inflammatory disease that arises as a consequence of energy imbalance. Obesity increases the risk of type 2 diabetes (T2D), by mechanisms that are not entirely clarified. Elevated circulating pro-inflammatory cytokines and free fatty acids (FFA) during obesity cause insulin resistance and ß-cell dysfunction, the two main features of T2D, which are both aggravated with the progressive development of hyperglycemia. The inflammatory kinase c-jun N-terminal kinase (JNK) responds to various cellular stress signals activated by cytokines, free fatty acids and hyperglycemia, and is a key mediator in the transition between obesity and T2D. Specifically, JNK mediates both insulin resistance and ß-cell dysfunction, and is therefore a potential target for T2D therapy.
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8
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Roma LP, Jonas JC. Nutrient Metabolism, Subcellular Redox State, and Oxidative Stress in Pancreatic Islets and β-Cells. J Mol Biol 2019; 432:1461-1493. [PMID: 31634466 DOI: 10.1016/j.jmb.2019.10.012] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 09/25/2019] [Accepted: 10/10/2019] [Indexed: 01/01/2023]
Abstract
Insulin-secreting pancreatic β-cells play a critical role in blood glucose homeostasis and the development of type 2 diabetes (T2D) in the context of insulin resistance. Based on data obtained at the whole cell level using poorly specific chemical probes, reactive oxygen species (ROS) such as superoxide and hydrogen peroxide have been proposed to contribute to the stimulation of insulin secretion by nutrients (positive role) and to the alterations of cell survival and secretory function in T2D (negative role). This raised the controversial hypothesis that any attempt to decrease β-cell oxidative stress and apoptosis in T2D would further impair insulin secretion. Over the last decade, the development of genetically-encoded redox probes that can be targeted to cellular compartments of interest and are specific of redox couples allowed the evaluation of short- and long-term effects of nutrients on β-cell redox changes at the subcellular level. The data indicated that the nutrient regulation of β-cell redox signaling and ROS toxicity is far more complex than previously thought and that the subcellular compartmentation of these processes cannot be neglected when evaluating the mechanisms of ROS production or the efficacy of antioxidant enzymes and antioxidant drugs under glucolipotoxic conditions and in T2D. In this review, we present what is currently known about the compartmentation of redox homeostatic systems and tools to investigate it. We then review data about the effects of nutrients on β-cell subcellular redox state under normal conditions and in the context of T2D and discuss challenges and opportunities in the field.
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Affiliation(s)
- Leticia P Roma
- Universität des Saarlandes, Biophysics Department, Center for Human and Molecular Biology, Kirbergerstrasse Building 48, 66421, Homburg/Saar, Germany
| | - Jean-Christophe Jonas
- Université Catholique de Louvain, Institute of Experimental and Clinical Research, Pole of Endocrinology, Diabetes and Nutrition, Avenue Hippocrate 55 (B1.55.06), B-1200 Brussels, Belgium.
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9
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Kandanur SGS, Tamang N, Golakoti NR, Nanduri S. Andrographolide: A natural product template for the generation of structurally and biologically diverse diterpenes. Eur J Med Chem 2019; 176:513-533. [DOI: 10.1016/j.ejmech.2019.05.022] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 04/22/2019] [Accepted: 05/06/2019] [Indexed: 01/11/2023]
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10
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Kumar SA, Delgado M, Mendez VE, Joddar B. Applications of stem cells and bioprinting for potential treatment of diabetes. World J Stem Cells 2019; 11:13-32. [PMID: 30705712 PMCID: PMC6354103 DOI: 10.4252/wjsc.v11.i1.13] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 12/26/2018] [Accepted: 01/05/2019] [Indexed: 02/06/2023] Open
Abstract
Currently, there does not exist a strategy that can reduce diabetes and scientists are working towards a cure and innovative approaches by employing stem cell-based therapies. On the other hand, bioprinting technology is a novel therapeutic approach that aims to replace the diseased or lost β-cells, insulin-secreting cells in the pancreas, which can potentially regenerate damaged organs such as the pancreas. Stem cells have the ability to differentiate into various cell lines including insulin-producing cells. However, there are still barriers that hamper the successful differentiation of stem cells into β-cells. In this review, we focus on the potential applications of stem cell research and bioprinting that may be targeted towards replacing the β-cells in the pancreas and may offer approaches towards treatment of diabetes. This review emphasizes on the applicability of employing both stem cells and other cells in 3D bioprinting to generate substitutes for diseased β-cells and recover lost pancreatic functions. The article then proceeds to discuss the overall research done in the field of stem cell-based bioprinting and provides future directions for improving the same for potential applications in diabetic research.
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Affiliation(s)
- Shweta Anil Kumar
- Inspired Materials and Stem-Cell Based Tissue Engineering Laboratory, Department of Metallurgical, Materials and Biomedical Engineering, University of Texas at El Paso, 500 W University Avenue, El Paso, TX 79968, United States
| | - Monica Delgado
- Inspired Materials and Stem-Cell Based Tissue Engineering Laboratory, Department of Metallurgical, Materials and Biomedical Engineering, University of Texas at El Paso, 500 W University Avenue, El Paso, TX 79968, United States
| | - Victor E Mendez
- Inspired Materials and Stem-Cell Based Tissue Engineering Laboratory, Department of Metallurgical, Materials and Biomedical Engineering, University of Texas at El Paso, 500 W University Avenue, El Paso, TX 79968, United States
| | - Binata Joddar
- Inspired Materials and Stem-Cell Based Tissue Engineering Laboratory, Department of Metallurgical, Materials and Biomedical Engineering, University of Texas at El Paso, 500 W University Avenue, El Paso, TX 79968, United States
- Border Biomedical Research Center, University of Texas at El Paso, 500 W University Avenue, El Paso, TX 79968, United States.
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11
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Tang C, Yeung LSN, Koulajian K, Zhang L, Tai K, Volchuk A, Giacca A. Glucose-Induced β-Cell Dysfunction In Vivo: Evidence for a Causal Role of C-jun N-terminal Kinase Pathway. Endocrinology 2018; 159:3643-3654. [PMID: 30215691 PMCID: PMC6195676 DOI: 10.1210/en.2018-00566] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 08/26/2018] [Indexed: 11/19/2022]
Abstract
Prolonged elevation of glucose can adversely affect β-cell function. Oxidative stress, which has been implicated in glucose-induced β-cell dysfunction, can activate c-jun N-terminal kinase (JNK). However, whether JNK is causal in glucose-induced β-cell dysfunction in vivo is unclear. Therefore, we aimed at investigating the causal role of JNK activation in in vivo models of glucose-induced β-cell dysfunction. Glucose-induced β-cell dysfunction was investigated in the presence or absence of JNK inhibition. JNK inhibition was achieved using either (i) the JNK-specific inhibitor SP600125 or (ii) JNK-1-null mice. (i) Rats or mice were infused intravenously with saline or glucose with or without SP600125. (ii) JNK-1 null mice and their littermate wild-type controls were infused intravenously with saline or glucose. Following the glucose infusion periods in rats and mice, β-cell function was assessed in isolated islets or in vivo using hyperglycemic clamps. Forty-eight-hour hyperglycemia at ~20 mM in rats or 96-hour hyperglycemia at ~13 mM in mice impaired β-cell function in isolated islets and in vivo. Inhibition of JNK using either SP600125 or JNK-1-null mice prevented glucose-induced β-cell dysfunction in isolated islets and in vivo. Islets of JNK-1-null mice exposed to hyperglycemia in vivo showed an increase in Pdx-1 and insulin 2 mRNA, whereas islets of wild-type mice did not. Together, these data show that JNK pathway is involved in glucose-induced β-cell dysfunction in vivo and is thus a potential therapeutic target for type 2 diabetes.
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Affiliation(s)
- Christine Tang
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Lucy Shu Nga Yeung
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Khajag Koulajian
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Liling Zhang
- Division of Cellular and Molecular Biology, Toronto General Research Institute, University Health Network, Toronto, Ontario, Canada
| | - Kevin Tai
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Allen Volchuk
- Keenan Research Centre for Biomedical Science, St. Michael Hospital, Toronto, Ontario, Canada
| | - Adria Giacca
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Department of Medicine, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Institute of Medical Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
- Correspondence: Adria Giacca, MD, Medical Sciences Building, 3336-1 King’s College Circle, Toronto, Ontario M5S 1A8, Canada. E-mail:
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12
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Palmitate and insulin counteract glucose-induced thioredoxin interacting protein (TXNIP) expression in insulin secreting cells via distinct mechanisms. PLoS One 2018; 13:e0198016. [PMID: 29813102 PMCID: PMC5973613 DOI: 10.1371/journal.pone.0198016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Accepted: 05/12/2018] [Indexed: 01/20/2023] Open
Abstract
Glucose and palmitate synergistically stimulate insulin secretion, but chronically elevated they induce apoptotic β-cell death. The glucotoxic effect has been attributed, at least partly, to the upregulation of the oxidative stress marker thioredoxin interacting protein (TXNIP). Palmitate downregulates TXNIP expression, the functional significance of which is still under debate. This study examines the mechanism and consequence of palmitate-mediated TXNIP regulation in insulin secreting cells. Palmitate (600 μM) reduced TXNIP mRNA levels in isolated human and mouse islets independently of FFAR1/GPR40. Similar effects of palmitate were observed in INS-1E cells and mimicked by other long chain fatty acids. The lowering of TXNIP mRNA was significant already 1 h after addition of palmitate, persisted for 24 h and was directly translated to changes in TXNIP protein. The pharmacological inhibition of palmitate-induced phosphorylation of AMPK, ERK1/2, JNK and PKCα/β by BML-275, PD98059, SP600125 and Gö6976, respectively, did not abolish palmitate-mediated TXNIP downregulation. The effect of palmitate was superimposed by a time-dependent (8 h and 24 h) decline of TXNIP mRNA and protein. This decline correlated with accumulation of secreted insulin into the medium. Accordingly, exogenously added insulin reduced TXNIP mRNA and protein levels, an effect counteracted by the insulin/IGF-1 receptor antagonist linsitinib. The inhibition of PI3K and Akt/PKB increased TXNIP mRNA levels. The histone deacetylase (HDAC1/2/3) inhibitor MS-275 completely abrogated the time-dependent, insulin-mediated reduction of TXNIP, leaving the effect of palmitate unaltered. Acute stimulation of insulin secretion and chronic accentuation of cell death by palmitate occurred independently of TXNIP regulation. On the contrary, palmitate antagonized glucose-augmented ROS production. In conclusion, glucose-induced TXNIP expression is efficiently antagonized by two independent mechanisms, namely via an autocrine activation of insulin/IGF-1 receptors involving HDAC and by palmitate attenuating oxidative stress of β-cells.
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Miki A, Ricordi C, Sakuma Y, Yamamoto T, Misawa R, Mita A, Molano RD, Vaziri ND, Pileggi A, Ichii H. Divergent antioxidant capacity of human islet cell subsets: A potential cause of beta-cell vulnerability in diabetes and islet transplantation. PLoS One 2018; 13:e0196570. [PMID: 29723228 PMCID: PMC5933778 DOI: 10.1371/journal.pone.0196570] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2017] [Accepted: 04/16/2018] [Indexed: 01/09/2023] Open
Abstract
Background Type 1 and Type 2 diabetes mellitus (T1DM and T2DM) are caused by beta(β)-cell loss and functional impairment. Identification of mechanisms of β-cell death and therapeutic interventions to enhance β-cell survival are essential for prevention and treatment of diabetes. Oxidative stress is a common feature of both T1DM and T2DM; elevated biomarkers of oxidative stress are detected in blood, urine and tissues including pancreas of patients with DM. Islet transplantation is a promising treatment for diabetes. However, exposure to stress (chemical and mechanical) and ischemia-reperfusion during isolation and transplantation causes islet loss by generation of reactive oxygen species (ROS). Human intracellular antioxidant enzymes and related molecules are essential defenses against ROS. Antioxidant enzyme levels including superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPX) have been shown to be low in islet cells. However, little is known about the expression and function of antioxidant enzymes within islet cell subsets. We evaluated the expression of the key antioxidant enzymes in β- and alpha(α)-cell and accessed effects of oxidative stress, islet isolation and transplantation on β/α-cell ratio and viability in human islets. Methods Human pancreata from T1DM, T2DM and non-diabetic deceased donors were obtained and analyzed by confocal microscopy. Isolated islets were (I) transplanted in the renal sub-capsular space of streptozotocin-induced diabetic nude mice (in vivo bioassay), or (II) exposed to oxidative (H2O2) and nitrosative (NO donor) stress for 24 hrs in vitro. The ratio, % viability and death of β- and α-cells, and DNA damage (8OHdG) were measured. Results and conclusions Catalase and GPX expression was much lower in β- than α-cells. The β/α-cell ratio fells significantly following islet isolation and transplantation. Exposure to oxidative stress caused a significantly lower survival and viability, with higher DNA damage in β- than α-cells. These findings identified the weakness of β-cell antioxidant capacity as a main cause of vulnerability to oxidative stress. Potential strategies to enhance β-cell antioxidant capacity might be effective in prevention/treatment of diabetes.
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Affiliation(s)
- Atsushi Miki
- Cell Transplant Center, Diabetes Research Institute, University of Miami, Miami, Florida, United States of America
| | - Camillo Ricordi
- Cell Transplant Center, Diabetes Research Institute, University of Miami, Miami, Florida, United States of America
| | - Yasunaru Sakuma
- Cell Transplant Center, Diabetes Research Institute, University of Miami, Miami, Florida, United States of America
| | - Toshiyuki Yamamoto
- Cell Transplant Center, Diabetes Research Institute, University of Miami, Miami, Florida, United States of America
| | - Ryosuke Misawa
- Cell Transplant Center, Diabetes Research Institute, University of Miami, Miami, Florida, United States of America
| | - Atsuyoshi Mita
- Cell Transplant Center, Diabetes Research Institute, University of Miami, Miami, Florida, United States of America
| | - Ruth D Molano
- Cell Transplant Center, Diabetes Research Institute, University of Miami, Miami, Florida, United States of America
| | - Nosratola D Vaziri
- Department of Medicine, University of California, Irvine, United States of America
| | - Antonello Pileggi
- Cell Transplant Center, Diabetes Research Institute, University of Miami, Miami, Florida, United States of America
| | - Hirohito Ichii
- Cell Transplant Center, Diabetes Research Institute, University of Miami, Miami, Florida, United States of America.,Department of Surgery, University of California, Irvine, United States of America
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Lu H, Bogdanovic E, Yu Z, Cho C, Liu L, Ho K, Guo J, Yeung LSN, Lehmann R, Hundal HS, Giacca A, Fantus IG. Combined Hyperglycemia- and Hyperinsulinemia-Induced Insulin Resistance in Adipocytes Is Associated With Dual Signaling Defects Mediated by PKC-ζ. Endocrinology 2018; 159:1658-1677. [PMID: 29370351 PMCID: PMC5939637 DOI: 10.1210/en.2017-00312] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 01/03/2018] [Indexed: 12/27/2022]
Abstract
A hyperglycemic and hyperinsulinemic environment characteristic of type 2 diabetes causes insulin resistance. In adipocytes, defects in both insulin sensitivity and maximum response of glucose transport have been demonstrated. To investigate the molecular mechanisms, freshly isolated rat adipocytes were incubated in control (5.6 mM glucose, no insulin) and high glucose (20 mM)/high insulin (100 nM) (HG/HI) for 18 hours to induce insulin resistance. Insulin-resistant adipocytes manifested decreased sensitivity of glucose uptake associated with defects in insulin receptor substrate (IRS)-1 Tyr phosphorylation, association of p85 subunit of phosphatidylinositol-3-kinase, Akt Ser473 and Thr308 phosphorylation, accompanied by impaired glucose transporter 4 translocation. In contrast, protein kinase C (PKC)-ζ activity was augmented by chronic HG/HI. Inhibition of PKC-ζ with a specific cell-permeable peptide reversed the signaling defects and insulin sensitivity of glucose uptake. Transfection of dominant-negative, kinase-inactive PKC-ζ blocked insulin resistance, whereas constitutively active PKC-ζ recapitulated the defects. The HG/HI incubation was associated with stimulation of IRS-1 Ser318 and Akt Thr34 phosphorylation, targets of PKC-ζ. Transfection of IRS-1 S318A and Akt T34A each partially corrected insulin signaling, whereas combined transfection of both completely normalized insulin signaling. In vivo hyperglycemia/hyperinsulinemia in rats for 48 hours similarly resulted in activation of PKC-ζ and increased phosphorylation of IRS-1 Ser318 and Akt Thr34. These data indicate that impairment of insulin signaling by chronic HG/HI is mediated by dual defects at IRS-1 and Akt mediated by PKC-ζ.
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Affiliation(s)
- Huogen Lu
- Department of Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada
- Toronto General Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Elena Bogdanovic
- Department of Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada
- Toronto General Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada
- Department of Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Zhiwen Yu
- Department of Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada
- Toronto General Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Charles Cho
- Department of Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada
- Department of Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Lijiang Liu
- Department of Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada
- Toronto General Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Karen Ho
- Department of Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada
- Toronto General Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - June Guo
- Department of Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Lucy S N Yeung
- Department of Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Reiner Lehmann
- Department of Internal Medicine IV, Endocrinology, Metabolism, Pathobiochemistry and Clinical Chemistry, University Hospital Tuebingen, Tuebingen, Germany
| | - Harinder S Hundal
- Division of Molecular Physiology Unit, Faculty of Life Sciences, University of Dundee, Dundee, United Kingdom
| | - Adria Giacca
- Department of Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - I George Fantus
- Department of Medicine, Mount Sinai Hospital, Toronto, Ontario, Canada
- Toronto General Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada
- Department of Physiology, Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
- Correspondence: I. George Fantus, MD, Departments of Medicine and Physiology, Mount Sinai Hospital, Joseph and Wolfe Lebovic Building, 60 Murray Street, 5th Floor, Room 5028, Toronto, Ontario M5T 3L9, Canada. E-mail:
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Piao F, Aadil RM, Suleman R, Li K, Zhang M, Wu P, Shahbaz M, Ahmed Z. Ameliorative effects of taurine against diabetes: a review. Amino Acids 2018; 50:487-502. [PMID: 29492671 DOI: 10.1007/s00726-018-2544-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 02/19/2018] [Indexed: 01/01/2023]
Abstract
Diets in rats and humans have shown promising results. Taurine improved glucagon activity, promoted glycemic stability, modified glucose levels, successfully addressed hyperglycemia via advanced glycation end-product control, improved insulin secretion and had a beneficial effect on insulin resistance. Taurine treatment performed well against oxidative stress in brain, increased the secretion of required hormones and protected against neuropathy, retinopathy and nephropathy in diabetes compared with the control. Taurine has been observed to be effective in treatments against diabetic hepatotoxicity, vascular problems and heart injury in diabetes. Taurine was shown to be effective against oxidative stress. The mechanism of action of taurine cannot be explained by one pathway, as it has many effects. Several of the pathways are the advanced glycation end-product pathway, PI3-kinase/AKT pathway and mitochondrial apoptosis pathway. The worldwide threat of diabetes underscores the urgent need for novel therapeutic measures against this disorder. Taurine (2-aminoethane sulfonic acid) is a natural compound that has been studied in diabetes and diabetes-induced complications.
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Affiliation(s)
- Fengyuan Piao
- School of Public Health, Dalian Medical University, Dalian, 116044, China.
| | - Rana Muhammad Aadil
- National Institute of Food Science and Technology, University of Agriculture Faisalabad, Faislabad, Pakistan
| | - Raheel Suleman
- Institute of Food Science and Technology, Graduate School of Chinese Academy of Agriculture Science, Beijing, China
| | - Kaixin Li
- School of Public Health, Dalian Medical University, Dalian, 116044, China
| | - Mengren Zhang
- School of Public Health, Dalian Medical University, Dalian, 116044, China
| | - Pingan Wu
- School of Public Health, Dalian Medical University, Dalian, 116044, China
| | - Muhammad Shahbaz
- Department of Food Science and Technology, Muhammad Nawaz Sharif University of Agriculture, Multan, Pakistan
| | - Zulfiqar Ahmed
- Department of Food Science and Technology, College of Environmental and Agricultural Sciences, Islamia University Bahawalpur, Bhawalpur, Pakistan
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Ke M, Wu H, Zhu Z, Zhang C, Zhang Y, Deng Y. Differential proteomic analysis of white adipose tissues from T2D KKAy mice by LC-ESI-QTOF. Proteomics 2017; 17. [PMID: 27995753 DOI: 10.1002/pmic.201600219] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 11/28/2016] [Accepted: 12/13/2016] [Indexed: 12/14/2022]
Abstract
Type 2 diabetes (T2D) has become a worldwide increasingly social health burden for its high morbidity and heightened prevalence. As one of the main tissues involved in uptake of glucose under the stimulation of insulin, WAT plays very important role in metabolic and homeostasis regulation. We performed a differential proteomics study to investigate alterations in epididymis fat pad of high fat diet fed T2D KKAy mice compared to normal fed C57BL/6J mice, by 18 O-labeling relative quantitative technique. Among 329 confidently identified proteins, 121 proteins showed significant changes with CV ≤ 20% (fold changes of >2 or <0.5 as threshold). According to GO classification, we found that altered proteins contained members of biological processes of metabolic process, oxidative stress, ion homeostasis, apoptosis and cell division. In metabolic, proteins assigned to fatty acid biosynthesis (FAS etc.) were decreased, the key enzyme (ACOX3) in β-oxidation process was increased. Increased glycolysis enzymes (ENOB etc.) and decreased TCA cycle related enzymes (SCOT1 etc.) suggested that glucose metabolism in mitochondria of T2D mice might be impaired. Elevated oxidative stress was observed with alterations of a series of oxidordeuctase (QSOX1 etc.). Besides, alterations of ion homeostasis (AT2C1 etc.) proteins were also observed. The enhancement of cell proliferation associated proteins (ELYS etc.) and inhibition of apoptosis associated proteins (RASF6 etc.) in WAT might contributed to the fat pad and body weight gain. Overall, these changes in WAT may serve as a reference for understanding the functional mechanism of T2D.
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Affiliation(s)
- Ming Ke
- Beijing Institute of Technology, School of life science, Haidian, Beijing, P. R. China
| | - Hanyan Wu
- Beijing Institute of Technology, School of life science, Haidian, Beijing, P. R. China
| | - Zhaoyang Zhu
- Beijing Institute of Technology, School of life science, Haidian, Beijing, P. R. China
| | - Chi Zhang
- Beijing Institute of Technology, School of life science, Haidian, Beijing, P. R. China
| | - Yongqian Zhang
- Beijing Institute of Technology, School of life science, Haidian, Beijing, P. R. China
| | - Yunlin Deng
- Beijing Institute of Technology, School of life science, Haidian, Beijing, P. R. China
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Diabetes-Related Induction of the Heme Oxygenase System and Enhanced Colocalization of Heme Oxygenase 1 and 2 with Neuronal Nitric Oxide Synthase in Myenteric Neurons of Different Intestinal Segments. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2017; 2017:1890512. [PMID: 29081883 PMCID: PMC5610792 DOI: 10.1155/2017/1890512] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 08/02/2017] [Accepted: 08/17/2017] [Indexed: 12/17/2022]
Abstract
Increase in hyperglycaemia-induced oxidative stress and decreased effectiveness of endogenous defense mechanisms plays an essential role in the initiation of diabetes-related neuropathy. We demonstrated that nitrergic myenteric neurons display different susceptibilities to diabetic damage in different gut segments. Therefore, we aim to reveal the gut segment-specific differences in the expression of heme oxygenase (HO) isoforms and the colocalization of these antioxidants with neuronal nitric oxide synthase (nNOS) in myenteric neurons. After ten weeks, samples from the duodenum, ileum, and colon of control and streptozotocin-induced diabetic rats were processed for double-labelling fluorescent immunohistochemistry and ELISA. The number of both HO-immunoreactive and nNOS/HO-immunoreactive myenteric neurons was the lowest in the ileal and the highest in the colonic ganglia of controls; it increased the most extensively in the ileum and was also elevated in the colon of diabetics. Although the total number of nitrergic neurons decreased in all segments, the proportion of nNOS-immunoreactive neurons colocalizing with HOs was enhanced robustly in the ileum and colon of diabetics. We presume that those nitrergic neurons which do not colocalize with HOs are the most seriously affected by diabetic damage. Therefore, the regional induction of the HO system is strongly correlated with diabetes-related region-specific nitrergic neuropathy.
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Wu N, Shen H, Wang Y, He B, Zhang Y, Bai Y, Du R, Du Q, Han P. Role of the PKCβII/JNK signaling pathway in acute glucose fluctuation-induced apoptosis of rat vascular endothelial cells. Acta Diabetol 2017; 54:727-736. [PMID: 28478520 DOI: 10.1007/s00592-017-0999-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 04/24/2017] [Indexed: 12/19/2022]
Abstract
AIMS The purpose of this study was to investigate the mechanism of vascular endothelial cell apoptosis induced by acute blood glucose fluctuation. METHODS Thirty rats were assigned to three groups: normal saline (SAL group), constant high glucose (CHG group) and acute blood glucose fluctuation (AFG) group. Other forty rats were assigned to SAL group, AFG group, LY group (PKCβ inhibitor LY333531 was injected intragastrically to the rats who were under acute blood glucose fluctuation) and SP group (JNK inhibitor SP600125 was injected intraperitoneally to the rats who were under acute blood glucose fluctuation). Oxidative stress and inflammatory cytokines were detected. TUNEL was performed to detect apoptosis. Pro-caspase-3, caspase-3 p17, JNK, PKC-βII and insulin signaling-related protein expression were tested by Western blotting. RESULTS After administration of LY333531, AFG-induced membrane translocation of PKCβII protein was inhibited, but SP600125 failed to affect AFG-induced PKCβII membrane translocation. After administration of LY333531, the AFG-induced increase in JNK activity was significantly compromised. LY333531 inhibited AFG-induced oxidative stress. However, SP600125 only slightly inhibited AFG-induced oxidative stress reaction (P > 0.05). Both LY333531 and SP600125 can reverse AFG-induced endothelial cell apoptosis increase, inflammatory cytokines levels rise and insulin signaling impairment. CONCLUSIONS It is necessary to actively control blood glucose and avoid significant glucose fluctuation. PKCβII/JNK may serve as a target, and inhibitors of PKCβII/JNK may be used to help prevent cardiovascular diseases in patients with poor glucose control or significant glucose fluctuation.
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Affiliation(s)
- Na Wu
- Department of Endocrinology, Shengjing Hospital of China Medical University, Shenyang, 110004, China
| | - Haitao Shen
- Department of Emergency, Shengjing Hospital of China Medical University, Shenyang, 110004, China
| | - Yanjun Wang
- Department of Endocrinology, Shengjing Hospital of China Medical University, Shenyang, 110004, China
| | - Bing He
- Department of Endocrinology, Shengjing Hospital of China Medical University, Shenyang, 110004, China
| | - Yongyan Zhang
- Department of Endocrinology, Shengjing Hospital of China Medical University, Shenyang, 110004, China
| | - Yu Bai
- Department of Endocrinology, Shengjing Hospital of China Medical University, Shenyang, 110004, China
| | - Runyu Du
- Department of Endocrinology, Shengjing Hospital of China Medical University, Shenyang, 110004, China
| | - Qiang Du
- Department of Endocrinology, Shengjing Hospital of China Medical University, Shenyang, 110004, China
| | - Ping Han
- Department of Endocrinology, Shengjing Hospital of China Medical University, Shenyang, 110004, China.
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Upregulation of UCP2 in beta-cells confers partial protection against both oxidative stress and glucotoxicity. Redox Biol 2017; 13:541-549. [PMID: 28755631 PMCID: PMC5537434 DOI: 10.1016/j.redox.2017.07.012] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 07/19/2017] [Accepted: 07/20/2017] [Indexed: 01/09/2023] Open
Abstract
Deterioration of pancreatic beta-cells plays a critical role in the development of type 2 diabetes. Among the various stressors contributing to these deleterious effects, glucotoxicity and superoxides have been proposed as major players. In this context, the mitochondrial uncoupling protein UCP2 is regularly associated with the stress response. In the present study, we tested the effects of UCP2 upregulation in mouse islets with beta-cell specific overexpression of UCP2 (RIP-UCP2). Islets were subjected to both chronic glucotoxicity (7 days at 30 mM glucose) and acute oxidative stress (200 µM H2O2 for 10 min). Increased UCP2 expression did not alter mitochondrial potential and ATP generation but protected against glucotoxic effects. Glucose-stimulated insulin secretion was altered by both glucotoxicity and oxidative stress, in particular through higher basal insulin release at non-stimulatory glucose concentrations. The secretory response to glucose stimulation was partially preserved in beta-cells overexpressing UCP2. The higher rate of cell death induced by chronic high glucose exposure was lower in RIP-UCP2 islets. Finally, superoxide production was reduced by high glucose, both under acute and chronic conditions, and not modified by UCP2 overexpression. In conclusion, upregulation of UCP2 conferred protective effects to the stressed beta-cell through mechanisms not directly associated with superoxide production. UCP2 upregulation protects pancreatic ß-cells against glucotoxicity. High glucose reduces superoxide production in pancreatic islets. UCP2 upregulation does not change superoxide production. UCP2 upregulation protects ß-cells against oxidative stress.
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Moon JS, Karunakaran U, Elumalai S, Lee IK, Lee HW, Kim YW, Won KC. Metformin prevents glucotoxicity by alleviating oxidative and ER stress-induced CD36 expression in pancreatic beta cells. J Diabetes Complications 2017; 31:21-30. [PMID: 27662780 DOI: 10.1016/j.jdiacomp.2016.09.001] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 08/18/2016] [Accepted: 09/05/2016] [Indexed: 12/27/2022]
Abstract
AIM/HYPOTHESIS Cluster determinant 36 (CD36), a fatty acid transporter, was reported to have a pivotal role in glucotoxicity-induced beta cell dysfunction. However, little is known about how glucotoxicity influences CD36 expression, and it is unknown whether this action can be counteracted by metformin. In the present study, we showed that metformin counteracts glucotoxicity by alleviating oxidative and endoplasmic reticulum (ER) stress-induced CD36 expression. METHODS We used primary rat islets as well as INS-1 cells for 72h to 24h with 30mM glucose, respectively. Thapsigargin was used as strong ER stressor, and Sulfo-N-succinimidyl oleate (SSO) and RNA interference were chosen for CD36 inhibition. Free fatty acid uptake was measured by radioisotope tracing technique. RESULTS Exposure of isolated rat islets to high glucose (HG) for 3days decreased insulin and pancreatic duodenal homeobox1 (Pdx1) mRNA expression, with the suppression of glucose-stimulated insulin secretion (GSIS) along with elevation of reactive oxygen species (ROS) levels. Incubation with metformin restored insulin and Pdx1 mRNA expression with significant improvements in GSIS and decrease in ROS production. HG exposure in INS-1 cells increased free fatty acid uptake via induction of CD36 along with impaired insulin and Pdx1 mRNA expression. Moreover, thapsigargin also increased the induction of CD36 expression. Metformin blocked HG- and thapsigargin-induced CD36 expression. In addition, the simultaneous inhibition of intracellular ROS production by metformin or CD36 activation by SSO or CD36 siRNA significantly decreased the apoptotic response in HG-treated INS-1 cells. CONCLUSION/INTERPRETATION In conclusion, metformin conferred protection against HG-induced apoptosis of pancreatic beta cells, largely by interfering with ROS production, and inhibited the CD36-mediated free fatty acid influx. This report provides evidence that the inhibition of CD36 may have potential therapeutic effects against hyperglycemia-induced beta cell damage in diabetes.
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Affiliation(s)
- Jun Sung Moon
- Department of Internal Medicine, Yeungnam University College of Medicine, Daegu, Republic of Korea
| | - Udayakumar Karunakaran
- Institute of Medical Science, Yeungnam University College of Medicine, Daegu, Republic of Korea
| | - Suma Elumalai
- Institute of Medical Science, Yeungnam University College of Medicine, Daegu, Republic of Korea
| | - In-Kyu Lee
- Department of Internal Medicine, Kyungpook National University School of Medicine, Daegu
| | - Hyoung Woo Lee
- Department of Internal Medicine, Yeungnam University College of Medicine, Daegu, Republic of Korea
| | - Yong-Woon Kim
- Department of Physiology, Yeungnam University College of Medicine, Daegu, Republic of Korea
| | - Kyu Chang Won
- Department of Internal Medicine, Yeungnam University College of Medicine, Daegu, Republic of Korea; Institute of Medical Science, Yeungnam University College of Medicine, Daegu, Republic of Korea.
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Lee J, Harris AN, Holley CL, Mahadevan J, Pyles KD, Lavagnino Z, Scherrer DE, Fujiwara H, Sidhu R, Zhang J, Huang SCC, Piston DW, Remedi MS, Urano F, Ory DS, Schaffer JE. Rpl13a small nucleolar RNAs regulate systemic glucose metabolism. J Clin Invest 2016; 126:4616-4625. [PMID: 27820699 DOI: 10.1172/jci88069] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 09/29/2016] [Indexed: 12/22/2022] Open
Abstract
Small nucleolar RNAs (snoRNAs) are non-coding RNAs that form ribonucleoproteins to guide covalent modifications of ribosomal and small nuclear RNAs in the nucleus. Recent studies have also uncovered additional non-canonical roles for snoRNAs. However, the physiological contributions of these small RNAs are largely unknown. Here, we selectively deleted four snoRNAs encoded within the introns of the ribosomal protein L13a (Rpl13a) locus in a mouse model. Loss of Rpl13a snoRNAs altered mitochondrial metabolism and lowered reactive oxygen species tone, leading to increased glucose-stimulated insulin secretion from pancreatic islets and enhanced systemic glucose tolerance. Islets from mice lacking Rpl13a snoRNAs demonstrated blunted oxidative stress responses. Furthermore, these mice were protected against diabetogenic stimuli that cause oxidative stress damage to islets. Our study illuminates a previously unrecognized role for snoRNAs in metabolic regulation.
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Genetic Predisposition to an Impaired Metabolism of the Branched-Chain Amino Acids and Risk of Type 2 Diabetes: A Mendelian Randomisation Analysis. PLoS Med 2016; 13:e1002179. [PMID: 27898682 PMCID: PMC5127513 DOI: 10.1371/journal.pmed.1002179] [Citation(s) in RCA: 284] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 10/20/2016] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Higher circulating levels of the branched-chain amino acids (BCAAs; i.e., isoleucine, leucine, and valine) are strongly associated with higher type 2 diabetes risk, but it is not known whether this association is causal. We undertook large-scale human genetic analyses to address this question. METHODS AND FINDINGS Genome-wide studies of BCAA levels in 16,596 individuals revealed five genomic regions associated at genome-wide levels of significance (p < 5 × 10-8). The strongest signal was 21 kb upstream of the PPM1K gene (beta in standard deviations [SDs] of leucine per allele = 0.08, p = 3.9 × 10-25), encoding an activator of the mitochondrial branched-chain alpha-ketoacid dehydrogenase (BCKD) responsible for the rate-limiting step in BCAA catabolism. In another analysis, in up to 47,877 cases of type 2 diabetes and 267,694 controls, a genetically predicted difference of 1 SD in amino acid level was associated with an odds ratio for type 2 diabetes of 1.44 (95% CI 1.26-1.65, p = 9.5 × 10-8) for isoleucine, 1.85 (95% CI 1.41-2.42, p = 7.3 × 10-6) for leucine, and 1.54 (95% CI 1.28-1.84, p = 4.2 × 10-6) for valine. Estimates were highly consistent with those from prospective observational studies of the association between BCAA levels and incident type 2 diabetes in a meta-analysis of 1,992 cases and 4,319 non-cases. Metabolome-wide association analyses of BCAA-raising alleles revealed high specificity to the BCAA pathway and an accumulation of metabolites upstream of branched-chain alpha-ketoacid oxidation, consistent with reduced BCKD activity. Limitations of this study are that, while the association of genetic variants appeared highly specific, the possibility of pleiotropic associations cannot be entirely excluded. Similar to other complex phenotypes, genetic scores used in the study captured a limited proportion of the heritability in BCAA levels. Therefore, it is possible that only some of the mechanisms that increase BCAA levels or affect BCAA metabolism are implicated in type 2 diabetes. CONCLUSIONS Evidence from this large-scale human genetic and metabolomic study is consistent with a causal role of BCAA metabolism in the aetiology of type 2 diabetes.
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Wu N, Shen H, Liu H, Wang Y, Bai Y, Han P. Acute blood glucose fluctuation enhances rat aorta endothelial cell apoptosis, oxidative stress and pro-inflammatory cytokine expression in vivo. Cardiovasc Diabetol 2016; 15:109. [PMID: 27496150 PMCID: PMC4974767 DOI: 10.1186/s12933-016-0427-0] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 07/22/2016] [Indexed: 01/04/2023] Open
Abstract
Background Complications of diabetes mellitus (DM) are related not only to elevated plasma glucose, but also plasma glucose fluctuations. However, the specific mechanism underlying the role of plasma glucose fluctuation in the pathogenesis of DM complications remains poorly understood. In the present study, the influence of acute fluctuant hyperglycemia and persistent hyperglycemia on vascular endothelial cell apoptosis, function, oxidative stress and inflammation was examined in vivo. Methods Rats were assigned to three different groups (n = 10/group) that received 48-h infusions of saline (SAL group), continuous 50 % glucose (constant high glucose group [CHG]), or intermittent 50 % glucose (acute blood glucose fluctuation group [AFG]). Plasma 8-isoprostaglandin, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and intercellular adhesion molecule-1 (ICAM-1) levels were quantified by using enzyme-linked immunosorbent assay (ELISA) commercial kits. Plasma insulin levels were measured by radioimmunoassays (RIAs) using kits. The aortic segment was collected. The levels of malondialdehyde (MDA) and activity of glutathione peroxidase (GSH-PX) were measured in endothelial homogenates prepared from endothelial cells harvested from the aorta using colorimetric kits. Apoptosis of vascular endothelial cells was determined with terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL). Endothelial dysfunction was assessed by isometric tension recording to evaluate the endothelial function. The expression of B cell lymphoma-2 (Bcl-2), Bcl-2 Associated X protein (Bax), pro caspase-3, caspase-3 p17, 3-nitrotyrosine (3-NT) and p47phox protein in rat aortic endothelial cells were tested with Western blot analysis. Endothelial cells reactive oxygen species (ROS) formation was determined using dihydroethidium-dependent fluorescence microtopography in aortic cryo-sections. Expression of IL-6, TNF-α and ICAM-1 mRNAs in vascular endothelial cells were determined by real-time quantitative PCR. Results Endothelial cells apoptosis and dysfunction were observed significantly in the aortas of the AFG group (P < 0.05). The AFG had reduced Bcl-2 and pro caspase-3 levels and enhanced Bax mitochondrial translocation and caspase-3 p17 protein levels in comparison with the CHG group (P < 0.05). Both AFG and CHG induced β-cell dysfunction and insulin resistance (P < 0.05). AFG increased MDA and 8-isoprostaglandin levels in plasma, oxidative stress in vascular endothelial cells, and inflammatory cytokines in plasma and vascular endothelial cells (P < 0.05). Conclusion Acute glucose fluctuation may cause significant oxidative stress and inflammation in endothelial cells, increase the adhesion of monocytes to endothelial cells, and elevate endothelial cell apoptosis, resulting in severe cardiovascular injury.
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Affiliation(s)
- Na Wu
- Department of Endocrinology, Shengjing Hospital of China Medical University, Shenyang, 110004, China
| | - Haitao Shen
- Department of Emergency, Shengjing Hospital of China Medical University, Shenyang, 110004, China
| | - Henan Liu
- Department of Ophthalmology, Shengjing Hospital of China Medical University, Shenyang, 110004, China
| | - Yanjun Wang
- Department of Endocrinology, Shengjing Hospital of China Medical University, Shenyang, 110004, China
| | - Yu Bai
- Department of Endocrinology, Shengjing Hospital of China Medical University, Shenyang, 110004, China
| | - Ping Han
- Department of Endocrinology, Shengjing Hospital of China Medical University, Shenyang, 110004, China.
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Pepin É, Al-Mass A, Attané C, Zhang K, Lamontagne J, Lussier R, Madiraju SRM, Joly E, Ruderman NB, Sladek R, Prentki M, Peyot ML. Pancreatic β-Cell Dysfunction in Diet-Induced Obese Mice: Roles of AMP-Kinase, Protein Kinase Cε, Mitochondrial and Cholesterol Metabolism, and Alterations in Gene Expression. PLoS One 2016; 11:e0153017. [PMID: 27043434 PMCID: PMC4820227 DOI: 10.1371/journal.pone.0153017] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 03/22/2016] [Indexed: 12/27/2022] Open
Abstract
Diet induced obese (DIO) mice can be stratified according to their weight gain in response to high fat diet as low responders (LDR) and high responders (HDR). This allows the study of β-cell failure and the transitions to prediabetes (LDR) and early diabetes (HDR). C57BL/6N mice were fed for 8 weeks with a normal chow diet (ND) or a high fat diet and stratified as LDR and HDR. Freshly isolated islets from ND, LDR and HDR mice were studied ex-vivo for mitochondrial metabolism, AMPK activity and signalling, the expression and activity of key enzymes of energy metabolism, cholesterol synthesis, and mRNA profiling. Severely compromised glucose-induced insulin secretion in HDR islets, as compared to ND and LDR islets, was associated with suppressed AMP-kinase activity. HDR islets also showed reduced acetyl-CoA carboxylase activity and enhanced activity of 3-hydroxy-3-methylglutaryl-CoA reductase, which led respectively to elevated fatty acid oxidation and increased cholesterol biosynthesis. HDR islets also displayed mitochondrial membrane hyperpolarization and reduced ATP turnover in the presence of elevated glucose. Expression of protein kinase Cε, which reduces both lipolysis and production of signals for insulin secretion, was elevated in DIO islets. Genes whose expression increased or decreased by more than 1.2-fold were minor between LDR and ND islets (17 differentially expressed), but were prominent between HDR and ND islets (1508 differentially expressed). In HDR islets, particularly affected genes were related to cell cycle and proliferation, AMPK signaling, mitochondrial metabolism and cholesterol metabolism. In conclusion, chronically reduced AMPK activity, mitochondrial dysfunction, elevated cholesterol biosynthesis in islets, and substantial alterations in gene expression accompany β-cell failure in HDR islets. The β-cell compensation process in the prediabetic state (LDR) is largely independent of transcriptional adaptive changes, whereas the transition to early diabetes (HDR) is associated with major alterations in gene expression.
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Affiliation(s)
- Émilie Pepin
- Montreal Diabetes Research Center and Centre de Recherche du CHUM, Montréal, Québec, Canada
| | - Anfal Al-Mass
- Montreal Diabetes Research Center and Centre de Recherche du CHUM, Montréal, Québec, Canada
- Departments of Medicine and Human Genetics, McGill University, Montreal, Québec, Canada
| | - Camille Attané
- Montreal Diabetes Research Center and Centre de Recherche du CHUM, Montréal, Québec, Canada
| | - Kezhuo Zhang
- Departments of Medicine and Human Genetics, McGill University, Montreal, Québec, Canada
| | - Julien Lamontagne
- Montreal Diabetes Research Center and Centre de Recherche du CHUM, Montréal, Québec, Canada
| | - Roxane Lussier
- Montreal Diabetes Research Center and Centre de Recherche du CHUM, Montréal, Québec, Canada
| | - S. R. Murthy Madiraju
- Montreal Diabetes Research Center and Centre de Recherche du CHUM, Montréal, Québec, Canada
| | - Erik Joly
- Montreal Diabetes Research Center and Centre de Recherche du CHUM, Montréal, Québec, Canada
| | - Neil B. Ruderman
- Departments of Medicine and Physiology and Biophysics, Boston University School of Medicine and Diabetes Unit, Boston Medical Center, Boston, MA, United States of America
| | - Robert Sladek
- Departments of Medicine and Human Genetics, McGill University, Montreal, Québec, Canada
| | - Marc Prentki
- Montreal Diabetes Research Center and Centre de Recherche du CHUM, Montréal, Québec, Canada
- Departments of Nutrition, Biochemistry and Molecular Medicine, Faculty of Medicine, University of Montréal, Montreal, Québec, Canada
- * E-mail: (MP); (MLP)
| | - Marie-Line Peyot
- Montreal Diabetes Research Center and Centre de Recherche du CHUM, Montréal, Québec, Canada
- * E-mail: (MP); (MLP)
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Shahidi S, Jabbarpour Z, Saidijam M, Esmaeili R, Komaki A, Hashemi Firouzi N. The Effects of the Synthetic Antioxidant, Tempol, on Serum Glucose and Lipid Profile of Diabetic and Non-Diabetic Rats. AVICENNA JOURNAL OF MEDICAL BIOCHEMISTRY 2016. [DOI: 10.17795/ajmb-31043] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
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26
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Bandsma RHJ, Ackerley C, Koulajian K, Zhang L, van Zutphen T, van Dijk TH, Xiao C, Giacca A, Lewis GF. A low-protein diet combined with low-dose endotoxin leads to changes in glucose homeostasis in weanling rats. Am J Physiol Endocrinol Metab 2015; 309:E466-73. [PMID: 26152763 DOI: 10.1152/ajpendo.00090.2015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 07/01/2015] [Indexed: 12/23/2022]
Abstract
Severe malnutrition is a leading cause of global childhood mortality, and infection and hypoglycemia or hyperglycemia are commonly present. The etiology behind the changes in glucose homeostasis is poorly understood. Here, we generated an animal model of severe malnutrition with and without low-grade inflammation to investigate the effects on glucose homeostasis. Immediately after weaning, rats were fed diets containing 5 [low-protein diet (LP)] or 20% protein [control diet (CTRL)], with or without repeated low-dose intraperitoneal lipopolysaccharide (LPS; 2 mg/kg), to mimic inflammation resulting from infections. After 4 wk on the diets, hyperglycemic clamps or euglycemic hyperinsulinemic clamps were performed with infusion of [U-(13)C6]glucose and [2-(13)C]glycerol to assess insulin secretion, action, and hepatic glucose metabolism. In separate studies, pancreatic islets were isolated for further analyses of insulin secretion and islet morphometry. Glucose clearance was reduced significantly by LP feeding alone (16%) and by LP feeding with LPS administration (43.8%) compared with control during the hyperglycemic clamps. This was associated with a strongly reduced insulin secretion in LP-fed rats in vivo as well as ex vivo in islets but signficantly enhanced whole body insulin sensitivity. Gluconeogenesis rates were unaffected by LP feeding, but glycogenolysis was higher after LP feeding. A protein-deficient diet in young rats leads to a susceptibility to low-dose endotoxin-induced impairment in glucose clearance with a decrease in the islet insulin secretory pathway. A protein-deficient diet is associated with enhanced peripheral insulin sensitivity but impaired insulin-mediated suppression of hepatic glycogenolysis.
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Affiliation(s)
- Robert H J Bandsma
- Division of Gastroenterology, Hepatology, and Nutrition, The Hospital for Sick Children, Toronto, Ontario, Canada; Physiology and Experimental Medicine Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Pediatrics, Center for Liver, Digestive, and Metabolic Diseases, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands;
| | - Cameron Ackerley
- Department of Paediatric Laboratory Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Khajag Koulajian
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada; Division of Endocrinology and Metabolism, Department of Medicine, University of Toronto, Toronto, Ontario, Canada; and
| | - Ling Zhang
- Physiology and Experimental Medicine Program, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Tim van Zutphen
- Department of Pediatrics, Center for Liver, Digestive, and Metabolic Diseases, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Theo H van Dijk
- Department of Pediatrics, Center for Liver, Digestive, and Metabolic Diseases, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Changting Xiao
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada; Division of Endocrinology and Metabolism, Department of Medicine, University of Toronto, Toronto, Ontario, Canada; and Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Adria Giacca
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada; Division of Endocrinology and Metabolism, Department of Medicine, University of Toronto, Toronto, Ontario, Canada; and Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
| | - Gary F Lewis
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada; Division of Endocrinology and Metabolism, Department of Medicine, University of Toronto, Toronto, Ontario, Canada; and Banting and Best Diabetes Centre, University of Toronto, Toronto, Ontario, Canada
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Ito T, Yoshikawa N, Ito H, Schaffer SW. Impact of taurine depletion on glucose control and insulin secretion in mice. J Pharmacol Sci 2015; 129:59-64. [PMID: 26382103 DOI: 10.1016/j.jphs.2015.08.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Revised: 08/19/2015] [Accepted: 08/21/2015] [Indexed: 11/26/2022] Open
Abstract
Taurine, an endogenous sulfur-containing amino acid, is found in millimolar concentrations in mammalian tissue, and its tissue content is altered by diet, disease and aging. The effectiveness of taurine administration against obesity and its related diseases, including type 2 diabetes, has been well documented. However, the impact of taurine depletion on glucose metabolism and fat deposition has not been elucidated. In this study, we investigated the effect of taurine depletion (in the taurine transporter (TauT) knockout mouse model) on blood glucose control and high fat diet-induced obesity. TauT-knockout (TauTKO) mice exhibited lower body weight and abdominal fat mass when maintained on normal chow than wild-type (WT) mice. Blood glucose disposal after an intraperitoneal glucose injection was faster in TauTKO mice than in WT mice despite lower serum insulin levels. Islet beta-cells (insulin positive area) were also decreased in TauTKO mice compared to WT mice. Meanwhile, overnutrition by high fat (60% fat)-diet could lead to obesity in TauTKO mice despite lower body weight under normal chow diet condition, indicating nutrition in normal diet is not enough for TauTKO mice to maintain body weight comparable to WT mice. In conclusion, taurine depletion causes enhanced glucose disposal despite lowering insulin levels and lower body weight, implying deterioration in tissue energy metabolism.
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Affiliation(s)
- Takashi Ito
- Hyogo University of Health Sciences, 1-3-6 Minatojima, Chuo-ku, Kobe, Hyogo, Japan.
| | - Natsumi Yoshikawa
- Hyogo University of Health Sciences, 1-3-6 Minatojima, Chuo-ku, Kobe, Hyogo, Japan
| | - Hiromi Ito
- Hyogo University of Health Sciences, 1-3-6 Minatojima, Chuo-ku, Kobe, Hyogo, Japan
| | - Stephen W Schaffer
- College of Medicine, University of South Alabama, 307 University Blvd. N, Mobile, AL 36688, USA
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Edalat A, Schulte-Mecklenbeck P, Bauer C, Undank S, Krippeit-Drews P, Drews G, Düfer M. Mitochondrial succinate dehydrogenase is involved in stimulus-secretion coupling and endogenous ROS formation in murine beta cells. Diabetologia 2015; 58:1532-41. [PMID: 25874444 DOI: 10.1007/s00125-015-3577-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 03/13/2015] [Indexed: 10/23/2022]
Abstract
AIMS/HYPOTHESIS Generation of reduction equivalents is a prerequisite for nutrient-stimulated insulin secretion. Mitochondrial succinate dehydrogenase (SDH) fulfils a dual function with respect to mitochondrial energy supply: (1) the enzyme is part of mitochondrial respiratory chains; and (2) it catalyses oxidation of succinate to fumarate in the Krebs cycle. The aim of our study was to elucidate the significance of SDH for beta cell stimulus-secretion coupling (SSC). METHODS Mitochondrial variables, reactive oxygen species (ROS) and cytosolic Ca(2+) concentration ([Ca(2+)]c) were measured by fluorescence techniques and insulin release by radioimmunoassay in islets or islet cells of C57Bl/6N mice. RESULTS Inhibition of SDH with 3-nitropropionic acid (3-NPA) or monoethyl fumarate (MEF) reduced glucose-stimulated insulin secretion. Inhibition of the ATP-sensitive K(+) channel (KATP channel) partly prevented this effect, whereas potentiation of antioxidant defence by superoxide dismutase mimetics (TEMPOL and mito-TEMPO) or by nuclear factor erythroid 2-related factor 2 (Nrf-2)-mediated upregulation of antioxidant enzymes (oltipraz, tert-butylhydroxyquinone) did not diminish the inhibitory influence of 3-NPA. Blocking SDH decreased glucose-stimulated increase in intracellular FADH2 concentration without alterations in NAD(P)H. In addition, 3-NPA and MEF drastically reduced glucose-induced hyperpolarisation of mitochondrial membrane potential, indicative of decreased ATP production. As a consequence, the glucose-stimulated rise in [Ca(2+)]c was significantly delayed and reduced. Acute application of 3-NPA interrupted glucose-driven oscillations of [Ca(2+)]c. 3-NPA per se did not elevate intracellular ROS, but instead prevented glucose-induced ROS accumulation. CONCLUSIONS/INTERPRETATION SDH is an important regulator of insulin secretion and ROS production. Inhibition of SDH interrupts membrane-potential-dependent SSC, pointing to a pivotal role of mitochondrial FAD/FADH2 homeostasis for the maintenance of glycaemic control.
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Affiliation(s)
- Armin Edalat
- Department of Pharmaceutical and Medicinal Chemistry, University of Münster, Corrensstraße 48, 48149, Münster, Germany
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Masuda Y, Vaziri ND, Li S, Le A, Hajighasemi-Ossareh M, Robles L, Foster CE, Stamos MJ, Al-Abodullah I, Ricordi C, Ichii H. The effect of Nrf2 pathway activation on human pancreatic islet cells. PLoS One 2015; 10:e0131012. [PMID: 26110640 PMCID: PMC4482439 DOI: 10.1371/journal.pone.0131012] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 05/26/2015] [Indexed: 12/30/2022] Open
Abstract
Background Pancreatic islets are known to contain low level of antioxidants that renders them vulnerable to oxidative stress. Nrf2 is the master regulator of numerous genes, encoding antioxidant, detoxifying, and cytoprotective molecules. Activation of Nrf2 pathway induces up-regulation of numerous genes encoding antioxidant and phase II detoxifying enzymes and related proteins. However, little is known regarding the role of this pathway in human islet cells. The aim was to investigate the effect of Nrf2 activator (dh404, CDDO-9,11-dihydro-trifluoroethyl amide) on human islet cells. Methods Human islets were obtained from cadaveric donors. After dh404 treatment, Nrf2 translocation, mRNA expression, and protein abundance of its key target gene products were examined. The proportion of dh404-treated or non-treated viable islet beta cells was analyzed using flowcytemetry. The cytoprotective effects against oxidative stress and production of inflammatory mediators, and in vivo islet function after transplantation were determined. Results Nrf2 nuclear translocation was confirmed by con-focal microscope within 2 hours after treatment, which was associated with a dose-dependent increase in mRNA expression of anti-oxidants, including NQO1, HO-1, and GCLC. Enhanced HO-1 expression in dh404 treated islets was confirmed by Western Blot assay. Islet function after transplantation (2000 IEQ/mouse) to diabetic nude mice was not affected with or without dh404 treatment. After induction of oxidative stress with hydrogen peroxide (200 μM) the proportion of dh404-treated viable islet cells was significantly higher in the dh404-treated than untreated islets (74% vs.57%; P<0.05). Dh404 significantly decreased production of cytokines/chemokines including IL-1β, IL-6, IFN-γ and MCP-1. Conclusion Treatment of human pancreatic islets with the potent synthetic Nrf2 activator, dh404, significantly increased expression of the key anti-oxidants enzymes, decreased inflammatory mediators in islets and conferred protection against oxidative stress in beta cells.
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Affiliation(s)
- Yuichi Masuda
- Department of Surgery, University of California Irvine, Irvine, California, United States of America
| | - Nosratola D. Vaziri
- Medicine, University of California Irvine, Irvine, California, United States of America
| | - Shiri Li
- Department of Surgery, University of California Irvine, Irvine, California, United States of America
| | - Aimee Le
- Department of Surgery, University of California Irvine, Irvine, California, United States of America
| | | | - Lourdes Robles
- Department of Surgery, University of California Irvine, Irvine, California, United States of America
| | - Clarence E. Foster
- Department of Surgery, University of California Irvine, Irvine, California, United States of America
| | - Michael J. Stamos
- Department of Surgery, University of California Irvine, Irvine, California, United States of America
| | - Ismail Al-Abodullah
- Southern California Islet Cell Resources Center, Department of Diabetes, Endocrinology and Metabolism, City of Hope National Medical Center and Beckman Research Institute, Duarte, California, United States of America
| | - Camillo Ricordi
- Diabetes Research Institute, University of Miami, Miami, Florida, United States of America
| | - Hirohito Ichii
- Department of Surgery, University of California Irvine, Irvine, California, United States of America
- * E-mail:
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Malin SK, Kirwan JP, Sia CL, González F. Pancreatic β-cell dysfunction in polycystic ovary syndrome: role of hyperglycemia-induced nuclear factor-κB activation and systemic inflammation. Am J Physiol Endocrinol Metab 2015; 308:E770-7. [PMID: 25714674 PMCID: PMC4420895 DOI: 10.1152/ajpendo.00510.2014] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 02/18/2015] [Indexed: 12/14/2022]
Abstract
In polycystic ovary syndrome (PCOS), oxidative stress is implicated in the development of β-cell dysfunction. However, the role of mononuclear cell (MNC)-derived inflammation in this process is unclear. We determined the relationship between β-cell function and MNC-derived nuclear factor-κB (NF-κB) activation and tumor necrosis factor-α (TNF-α) secretion in response to a 2-h 75-g oral glucose tolerance test (OGTT) in normoglycemic women with PCOS (15 lean, 15 obese) and controls (16 lean, 14 obese). First- and second-phase β-cell function was calculated as glucose-stimulated insulin secretion (insulin/glucose area under the curve for 0-30 and 60-120 min, respectively) × insulin sensitivity (Matsuda Index derived from the OGTT). Glucose-stimulated NF-κB activation and TNF-α secretion from MNC, and fasting plasma thiobarbituric acid-reactive substances (TBARS) and high-sensitivity C-reactive protein (hs-CRP) were also assessed. In obese women with PCOS, first- and second-phase β-cell function was lower compared with lean and obese controls. Compared with lean controls, women with PCOS had greater change from baseline in NF-κB activation and TNF-α secretion, and higher plasma TBARS. β-Cell function was inversely related to NF-κB activation (1st and 2nd) and TNF-α secretion (1st), and plasma TBARS and hs-CRP (1st and 2nd). First- and second-phase β-cell function also remained independently linked to NF-κB activation after adjustment for body fat percentage and TBARS. In conclusion, β-cell dysfunction in PCOS is linked to hyperglycemia-induced NF-κB activation from MNC and systemic inflammation. These data suggest that in PCOS, inflammation may play a role in impairing insulin secretion before the development of overt hyperglycemia.
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Affiliation(s)
- Steven K Malin
- Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio; Department of Nutrition, School of Medicine, Case Western Reserve University, Cleveland, Ohio; and
| | - John P Kirwan
- Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio; Department of Nutrition, School of Medicine, Case Western Reserve University, Cleveland, Ohio; and
| | - Chang Ling Sia
- Department of Obstetrics and Gynecology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Frank González
- Department of Obstetrics and Gynecology, Indiana University School of Medicine, Indianapolis, Indiana
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Luo X, Li R, Yan LJ. Roles of Pyruvate, NADH, and Mitochondrial Complex I in Redox Balance and Imbalance in β Cell Function and Dysfunction. J Diabetes Res 2015; 2015:512618. [PMID: 26568959 PMCID: PMC4629043 DOI: 10.1155/2015/512618] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Revised: 11/26/2014] [Accepted: 11/27/2014] [Indexed: 12/25/2022] Open
Abstract
Pancreatic β cells not only use glucose as an energy source, but also sense blood glucose levels for insulin secretion. While pyruvate and NADH metabolic pathways are known to be involved in regulating insulin secretion in response to glucose stimulation, the roles of many other components along the metabolic pathways remain poorly understood. Such is the case for mitochondrial complex I (NADH/ubiquinone oxidoreductase). It is known that normal complex I function is absolutely required for episodic insulin secretion after a meal, but the role of complex I in β cells in the diabetic pancreas remains to be investigated. In this paper, we review the roles of pyruvate, NADH, and complex I in insulin secretion and hypothesize that complex I plays a crucial role in the pathogenesis of β cell dysfunction in the diabetic pancreas. This hypothesis is based on the establishment that chronic hyperglycemia overloads complex I with NADH leading to enhanced complex I production of reactive oxygen species. As nearly all metabolic pathways are impaired in diabetes, understanding how complex I in the β cells copes with elevated levels of NADH in the diabetic pancreas may provide potential therapeutic strategies for diabetes.
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Affiliation(s)
- Xiaoting Luo
- Department of Pharmaceutical Sciences, UNT System College of Pharmacy, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, USA
- Department of Biochemistry and Molecular Biology, Gannan Medical University, Ganzhou, Jiangxi 341000, China
| | - Rongrong Li
- Department of Pharmaceutical Sciences, UNT System College of Pharmacy, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, USA
| | - Liang-Jun Yan
- Department of Pharmaceutical Sciences, UNT System College of Pharmacy, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, USA
- *Liang-Jun Yan:
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Ghosal A, Sekar TV, Said HM. Biotin uptake by mouse and human pancreatic beta cells/islets: a regulated, lipopolysaccharide-sensitive carrier-mediated process. Am J Physiol Gastrointest Liver Physiol 2014; 307:G365-73. [PMID: 24904078 PMCID: PMC4121639 DOI: 10.1152/ajpgi.00157.2014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Biotin is essential for the normal function of pancreatic beta cells. These cells obtain biotin from their surroundings via transport across their cell membrane. Little is known about the uptake mechanism involved, how it is regulated, and how it is affected by internal and external factors. We addressed these issues using the mouse-derived pancreatic beta-TC-6 cells and freshly isolated mouse and human primary pancreatic beta cells as models. The results showed biotin uptake by pancreatic beta-TC-6 cells occurs via a Na(+)-dependent, carrier-mediated process, that is sensitive to desthiobiotin, as well as to pantothenic acid and lipoate; the process is also saturable as a function of concentration (apparent Km = 22.24 ± 5.5 μM). These cells express the sodium-dependent multivitamin transporter (SMVT), whose knockdown (with doxycycline-inducible shRNA) led to a sever inhibition in biotin uptake. Similarly, uptake of biotin by mouse and human primary pancreatic islets is Na(+)-dependent and carrier-mediated, and both cell types express SMVT. Biotin uptake by pancreatic beta-TC-6 cells is also adaptively regulated (via transcriptional mechanism) by extracellular substrate level. Chronic treatment of pancreatic beta-TC-6 cells with bacterial lipopolysaccharides (LPS) leads to inhibition in biotin uptake. This inhibition is mediated via a Toll-Like receptor 4-mediated process and involves a decrease in membrane expression of SMVT. These findings show, for the first time, that pancreatic beta cells/islets take up biotin via a specific and regulated carrier-mediated process, and that the process is sensitive to the effect of LPS.
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Affiliation(s)
- Abhisek Ghosal
- Departments of Medicine and Physiology/Biophysics, University of California, Irvine, California; and Department of Veterans Affairs Medical Center, Long Beach, California
| | - Thillai V. Sekar
- Departments of Medicine and Physiology/Biophysics, University of California, Irvine, California; and Department of Veterans Affairs Medical Center, Long Beach, California
| | - Hamid M. Said
- Departments of Medicine and Physiology/Biophysics, University of California, Irvine, California; and Department of Veterans Affairs Medical Center, Long Beach, California
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Wright JR, Xu BY. That which does not kill us makes us stronger--does Nietzsche's quote apply to islets? A re-evaluation of the passenger leukocyte theory, free radicals, and glucose toxicity in islet cell transplantation. Med Hypotheses 2014; 83:92-8. [PMID: 24767938 DOI: 10.1016/j.mehy.2014.03.036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Accepted: 03/28/2014] [Indexed: 11/26/2022]
Abstract
In clinical islet transplantation, isolated islets are embolized into the liver via the portal vein (PV); however, up to 70% of the islets are lost in the first few days after transplantation (i.e., too quickly to be mediated by the adaptive immune system). Part of early loss is due to instant blood-mediated inflammatory reaction, an immune/thrombotic process caused by islets interacting with complement. We have shown that glucose toxicity (GT) also plays a critical role based upon the observation that islets embolized into the PVs of diabetic athymic mice are rapidly lost but, if recipients are not diabetic, the islet grafts persist. Using donor islets resistant to the β-cell toxin streptozotocin, we have shown that intraportal islets engrafted in non-diabetic athymic mice for as little as 3 days will maintain normoglycemia when streptozotocin is administered destroying the recipient's native pancreas β-cells. What is the mechanism of GT in β-cells? Chronic exposure to hyperglycemia over-exerts β-cells and their electron transport chains leak superoxide radicals during aerobic metabolism. Here we reinterpret old data and present some compelling new data supporting a new model of early intraportal islet graft loss. We hypothesize that diabetes stimulates overproduction of superoxide in both the β-cells of the islet grafts and the endothelial cells lining the intraportal microvasculature adjacent to where the embolized islets become lodged. This double dose of oxidant damage stresses both the islets, which are highly susceptible to free radicals because of inherent low levels of scavenging enzymes, and the adjacent hepatic endothelial cells. This, superimposed upon localized endothelial damage caused by embolization, precipitates inflammation and coagulation which further damages islet grafts. Based upon this model, we predict that pre-exposing islets to sub-lethal hyperoxia should up-regulate islet free radical scavenging enzyme levels and promote initial engraftment; reinterpretation of 30 years old "passenger leukocyte" data and preliminary new data support this. Other data suggests that pre-exposure of recipients to hyperoxia could up-regulate antioxidant enzymes in the hepatic endothelium. The combination of both effects could markedly enhance early intraportal islet graft survival and engraftment. Finally, if our model is correct, current in vitro and in vivo tests used to test batches of harvested islets for viability and function prior to transplantation are poorly conceived (n.b., it is already well-known that results using these tests often do not predict clinical islet transplantation success) and a different testing paradigm is suggested.
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Affiliation(s)
- J R Wright
- University of Calgary, Department of Pathology & Laboratory Medicine and Calgary Laboratory Services, Calgary, Alberta, Canada.
| | - B-Y Xu
- University of Calgary, Department of Pathology & Laboratory Medicine and Calgary Laboratory Services, Calgary, Alberta, Canada
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Jabbarpour Z, Shahidi S, Saidijam M, Sarihi A, Hassanzadeh T, Esmaeili R. Effect of tempol on the passive avoidance and novel object recognition task in diabetic rats. Brain Res Bull 2014; 101:51-6. [PMID: 24412412 DOI: 10.1016/j.brainresbull.2013.12.013] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 12/10/2013] [Accepted: 12/30/2013] [Indexed: 01/11/2023]
Abstract
Diabetes mellitus (DM) has several effects, including cognitive impairment. Oxidative stress is associated with complications from diabetes. It seems that antioxidants can reduce some complications of the diabetes induced by oxidative stress. The objective of this study was to evaluate the effect of synthetic antioxidant, tempol on the passive avoidance (PA) memory and novel object recognition (NOR) tests in the diabetic rats. Forty male Wistar rats randomly divided into the control, diabetic, diabetic receiving tempol and healthy receiving tempol groups. Diabetes was induced by injection of streptozotocin (STZ) (60 mg/kg, i.p.). Then, the rats received saline or tempol (30 mg/kg) orally by gavages for 60 days. After that, they were assessed using the PA memory and NOR tests. The results of NOR test showed that the discrimination index (DI) in the healthy receiving tempol group and diabetic control group was significantly lower than control group. Also the amount of this index in diabetic receiving tempol group was significantly higher than diabetic group. The results of PA test indicated that the number of trials to acquisition in the diabetic rats is significantly more than control and diabetic tempol treated groups. Also, the time spent in the dark compartment (TDC) in the control and diabetic receiving tempol groups was less than diabetic group. TDC in the healthy receiving tempol group was more than control group. It can be concluded that although use of tempol is restricted as a cognitive enhancer in non-diabetic subjects but long-term administration of synthetic antioxidant, tempol, is able to dramatically improve diabetes-induced learning and memory deficit in both PA and NOR tests.
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Affiliation(s)
- Zahra Jabbarpour
- Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Siamak Shahidi
- Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran.
| | - Massoud Saidijam
- Research Center for Molecular Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Abdolrahman Sarihi
- Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Taghi Hassanzadeh
- Department of Clinical Biochemistry, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Rasoul Esmaeili
- School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
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Malin SK, Kirwan JP, Sia CL, González F. Glucose-stimulated oxidative stress in mononuclear cells is related to pancreatic β-cell dysfunction in polycystic ovary syndrome. J Clin Endocrinol Metab 2014; 99:322-9. [PMID: 24203060 PMCID: PMC3879676 DOI: 10.1210/jc.2013-3177] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
CONTEXT Oxidative stress induced by reactive oxygen species (ROS) is involved in the development of pancreatic β-cell dysfunction. OBJECTIVE We determined the relationship between mononuclear cell (MNC)-derived ROS generation and p47phox protein content in response to glucose ingestion and β-cell function in women with polycystic ovary syndrome (PCOS). DESIGN This was a cross-sectional study. SETTING This study was conducted at an academic medical center. PARTICIPANTS Twenty-nine normoglycemic women with PCOS (13 lean, 16 obese) and 25 ovulatory controls (16 lean, 9 obese) underwent a 3-h 75-g oral glucose tolerance test (OGTT). MAIN OUTCOME VARIABLES Pancreatic β-cell function was calculated as glucose-stimulated insulin secretion (insulin/glucose area under the curve0-30 min; GSIS)×Matsuda index-derived insulin sensitivity (ISOGTT). ROS generation was measured by chemiluminescence, and p47phox protein was quantified by Western blotting in MNC isolated from blood samples obtained at 0 and 2 hours of the OGTT. RESULTS Compared with controls, women with PCOS exhibited a higher percent change from baseline in ROS generation and p47phox protein in conjunction with greater GSIS and a tendency toward lower β-cell function. Lean women with PCOS exhibited a greater percent change from baseline in ROS generation and p47phox protein yet had similar GSIS responses compared with lean controls despite having lower ISOGTT. For the combined groups, β-cell function was inversely related to ROS generation and p47phox protein. GSIS was directly related to body mass index, central obesity, and circulating androgens. CONCLUSION In normoglycemic women, obesity plays a role in exaggerating GSIS. However, MNC-derived oxidative stress is independent of obesity and may contribute to the decline in β-cell function in women with PCOS.
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Affiliation(s)
- Steven K Malin
- Department of Pathobiology (S.K.M., J.P.K.), Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195; Department of Nutrition (S.K.M., J.P.K.), School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106; and Department of Obstetrics and Gynecology (C.L.S., F.G.), Indiana University School of Medicine, Indianapolis, Indiana 46202
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Askwith T. Taurine Treatment for Complications of Diabetes. OXIDATIVE STRESS IN APPLIED BASIC RESEARCH AND CLINICAL PRACTICE 2014. [DOI: 10.1007/978-1-4899-8035-9_10] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Prevost G, Arabo A, Jian L, Quelennec E, Cartier D, Hassan S, Falluel-Morel A, Tanguy Y, Gargani S, Lihrmann I, Kerr-Conte J, Lefebvre H, Pattou F, Anouar Y. The PACAP-regulated gene selenoprotein T is abundantly expressed in mouse and human β-cells and its targeted inactivation impairs glucose tolerance. Endocrinology 2013; 154:3796-806. [PMID: 23913443 DOI: 10.1210/en.2013-1167] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Selenoproteins are involved in the regulation of redox status, which affects several cellular processes, including cell survival and homeostasis. Considerable interest has arisen recently concerning the role of selenoproteins in the regulation of glucose metabolism. Here, we found that selenoprotein T (SelT), a new thioredoxin-like protein of the endoplasmic reticulum, is present at high levels in human and mouse pancreas as revealed by immunofluorescence and quantitative PCR. Confocal immunohistochemistry studies revealed that SelT is mostly confined to insulin- and somatostatin-producing cells in mouse and human islets. To elucidate the role of SelT in β-cells, we generated, using a Cre-Lox strategy, a conditional pancreatic β-cell SelT-knockout C57BL/6J mice (SelT-insKO) in which SelT gene disruption is under the control of the rat insulin promoter Cre gene. Glucose administration revealed that male SelT-insKO mice display impaired glucose tolerance. Although insulin sensitivity was not modified in the mutant mice, the ratio of glucose to insulin was significantly higher in the SelT-insKO mice compared with wild-type littermates, pointing to a deficit in insulin production/secretion in mutant mice. In addition, morphometric analysis showed that islets from SelT-insKO mice were smaller and that their number was significantly increased compared with islets from their wild-type littermates. Finally, we found that SelT is up-regulated by pituitary adenylate cyclase-activating polypeptide (PACAP) in β-pancreatic cells and that SelT could act by facilitating a feed-forward mechanism to potentiate insulin secretion induced by the neuropeptide. Our findings are the first to show that the PACAP-regulated SelT is localized in pancreatic β- and δ-cells and is involved in the control of glucose homeostasis.
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Affiliation(s)
- Gaëtan Prevost
- INSERM U982, Neuronal and Neuroendocrine Differentiation and Communication Laboratory, Sciences Faculty, University of Rouen, Place Emile Blondel, 76 821 Mont-Saint-Aignan cedex, France.
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Shirakawa J, Togashi Y, Sakamoto E, Kaji M, Tajima K, Orime K, Inoue H, Kubota N, Kadowaki T, Terauchi Y. Glucokinase activation ameliorates ER stress-induced apoptosis in pancreatic β-cells. Diabetes 2013; 62:3448-58. [PMID: 23801577 PMCID: PMC3781485 DOI: 10.2337/db13-0052] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The derangement of endoplasmic reticulum (ER) homeostasis triggers β-cell apoptosis, leading to diabetes. Glucokinase upregulates insulin receptor substrate 2 (IRS-2) expression in β-cells, but the role of glucokinase and IRS-2 in ER stress has been unclear. In this study, we investigated the impact of glucokinase activation by glucokinase activator (GKA) on ER stress in β-cells. GKA administration improved β-cell apoptosis in Akita mice, a model of ER stress-mediated diabetes. GKA increased the expression of IRS-2 in β-cells, even under ER stress. Both glucokinase-deficient Akita mice and IRS-2-deficient Akita mice exhibited an increase in β-cell apoptosis, compared with Akita mice. β-cell-specific IRS-2-overexpressing (βIRS-2-Tg) Akita mice showed less β-cell apoptosis than Akita mice. IRS-2-deficient islets were vulnerable, but βIRS-2-Tg islets were resistant to ER stress-induced apoptosis. Meanwhile, GKA regulated the expressions of C/EBP homologous protein (CHOP) and other ER stress-related genes in an IRS-2-independent fashion in islets. GKA suppressed the expressions of CHOP and Bcl2-associated X protein (Bax) and protected against β-cell apoptosis under ER stress in an ERK1/2-dependent, IRS-2-independent manner. Taken together, GKA ameliorated ER stress-mediated apoptosis by harmonizing IRS-2 upregulation and the IRS-2-independent control of apoptosis in β-cells.
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Affiliation(s)
- Jun Shirakawa
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
| | - Yu Togashi
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
| | - Eri Sakamoto
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
| | - Mitsuyo Kaji
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
| | - Kazuki Tajima
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
| | - Kazuki Orime
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
| | - Hideaki Inoue
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
| | - Naoto Kubota
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, University of Tokyo, Tokyo, Japan
| | - Takashi Kadowaki
- Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, University of Tokyo, Tokyo, Japan
| | - Yasuo Terauchi
- Department of Endocrinology and Metabolism, Graduate School of Medicine, Yokohama City University, Yokohama, Japan
- Corresponding author: Yasuo Terauchi,
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Zhu Y, You W, Wang H, Li Y, Qiao N, Shi Y, Zhang C, Bleich D, Han X. MicroRNA-24/MODY gene regulatory pathway mediates pancreatic β-cell dysfunction. Diabetes 2013; 62:3194-206. [PMID: 23761103 PMCID: PMC3749364 DOI: 10.2337/db13-0151] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Overnutrition and genetics both contribute separately to pancreatic β-cell dysfunction, but how these factors interact is unclear. This study was aimed at determining whether microRNAs (miRNAs) provide a link between these factors. In this study, miRNA-24 (miR-24) was highly expressed in pancreatic β-cells and further upregulated in islets from genetic fatty (db/db) or mice fed a high-fat diet, and islets subject to oxidative stress. Overexpression of miR-24 inhibited insulin secretion and β-cell proliferation, potentially involving 351 downregulated genes. By using bioinformatic analysis combined with luciferase-based promoter activity assays and quantitative real-time PCR assays, we identified two maturity-onset diabetes of the young (MODY) genes as direct targets of miR-24. Silencing either of these MODY genes (Hnf1a and Neurod1) mimicked the cellular phenotype caused by miR-24 overexpression, whereas restoring their expression rescued β-cell function. Our findings functionally link the miR-24/MODY gene regulatory pathway to the onset of type 2 diabetes and create a novel network between nutrient overload and genetic diabetes via miR-24.
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Affiliation(s)
- Yunxia Zhu
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Jiangsu Diabetes Center, Nanjing Medical University, Nanjing, Jiangsu, People’s Republic of China
| | - Weiyan You
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Jiangsu Diabetes Center, Nanjing Medical University, Nanjing, Jiangsu, People’s Republic of China
| | - Hongdong Wang
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Jiangsu Diabetes Center, Nanjing Medical University, Nanjing, Jiangsu, People’s Republic of China
| | - Yating Li
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Jiangsu Diabetes Center, Nanjing Medical University, Nanjing, Jiangsu, People’s Republic of China
| | - Nan Qiao
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Jiangsu Diabetes Center, Nanjing Medical University, Nanjing, Jiangsu, People’s Republic of China
| | - Yuguang Shi
- Department of Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, Pennsylvania
| | - Chenyu Zhang
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, Jiangsu, People’s Republic of China
| | - David Bleich
- University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark, New Jersey
| | - Xiao Han
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Jiangsu Diabetes Center, Nanjing Medical University, Nanjing, Jiangsu, People’s Republic of China
- Corresponding author: Xiao Han,
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Koulajian K, Ivovic A, Ye K, Desai T, Shah A, Fantus IG, Ran Q, Giacca A. Overexpression of glutathione peroxidase 4 prevents β-cell dysfunction induced by prolonged elevation of lipids in vivo. Am J Physiol Endocrinol Metab 2013; 305:E254-62. [PMID: 23695217 DOI: 10.1152/ajpendo.00481.2012] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
We have shown that oxidative stress is a mechanism of free fatty acid (FFA)-induced β-cell dysfunction. Unsaturated fatty acids in membranes, including plasma and mitochondrial membranes, are substrates for lipid peroxidation, and lipid peroxidation products are known to cause impaired insulin secretion. Therefore, we hypothesized that mice overexpressing glutathione peroxidase-4 (GPx4), an enzyme that specifically reduces lipid peroxides, are protected from fat-induced β-cell dysfunction. GPx4-overexpressing mice and their wild-type littermate controls were infused intravenously with saline or oleate for 48 h, after which reactive oxygen species (ROS) were imaged, using dihydrodichlorofluorescein diacetate in isolated islets, and β-cell function was assessed ex vivo in isolated islets and in vivo during hyperglycemic clamps. Forty-eight-hour FFA elevation in wild-type mice increased ROS and the lipid peroxidation product malondialdehyde and impaired β-cell function ex vivo in isolated islets and in vivo, as assessed by decreased disposition index. Also, islets of wild-type mice exposed to oleate for 48 h had increased ROS and lipid peroxides and decreased β-cell function. In contrast, GPx4-overexpressing mice showed no FFA-induced increase in ROS and lipid peroxidation and were protected from the FFA-induced impairment of β-cell function assessed in vitro, ex vivo and in vivo. These results implicate lipid peroxidation in FFA-induced β-cell dysfunction.
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Affiliation(s)
- Khajag Koulajian
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
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Sasaki M, Fujimoto S, Sato Y, Nishi Y, Mukai E, Yamano G, Sato H, Tahara Y, Ogura K, Nagashima K, Inagaki N. Reduction of reactive oxygen species ameliorates metabolism-secretion coupling in islets of diabetic GK rats by suppressing lactate overproduction. Diabetes 2013; 62:1996-2003. [PMID: 23349483 PMCID: PMC3661648 DOI: 10.2337/db12-0903] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
We previously demonstrated that impaired glucose-induced insulin secretion (IS) and ATP elevation in islets of Goto-Kakizaki (GK) rats, a nonobese model of diabetes, were significantly restored by 30-60-min suppression of endogenous reactive oxygen species (ROS) overproduction. In this study, we investigated the effect of a longer (12 h) suppression of ROS on metabolism-secretion coupling in β-cells by exposure to tempol, a superoxide (O2(-)) dismutase mimic, plus ebselen, a glutathione peroxidase mimic (TE treatment). In GK islets, both H2O2 and O2(-) were sufficiently reduced and glucose-induced IS and ATP elevation were improved by TE treatment. Glucose oxidation, an indicator of Krebs cycle velocity, also was improved by TE treatment at high glucose, whereas glucokinase activity, which determines glycolytic velocity, was not affected. Lactate production was markedly increased in GK islets, and TE treatment reduced lactate production and protein expression of lactate dehydrogenase and hypoxia-inducible factor 1α (HIF1α). These results indicate that the Warburg-like effect, which is characteristic of aerobic metabolism in cancer cells by which lactate is overproduced with reduced linking to mitochondria metabolism, plays an important role in impaired metabolism-secretion coupling in diabetic β-cells and suggest that ROS reduction can improve mitochondrial metabolism by suppressing lactate overproduction through the inhibition of HIF1α stabilization.
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Affiliation(s)
- Mayumi Sasaki
- Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Shimpei Fujimoto
- Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, Japan
- Department of Endocrinology, Metabolism, and Nephrology, Kochi Medical School, Kochi University, Nankoku, Japan
| | - Yuichi Sato
- Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Yuichi Nishi
- Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, Japan
- Department of Endocrinology, Metabolism, and Nephrology, Kochi Medical School, Kochi University, Nankoku, Japan
| | - Eri Mukai
- Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Gen Yamano
- Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Hiroki Sato
- Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Yumiko Tahara
- Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Kasane Ogura
- Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Kazuaki Nagashima
- Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Nobuya Inagaki
- Department of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, Japan
- Corresponding author: Nobuya Inagaki,
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Tang C, Marchand K, Lam L, Lux-Lantos V, Thyssen SM, Guo J, Giacca A, Arany E. Maternal taurine supplementation in rats partially prevents the adverse effects of early-life protein deprivation on β-cell function and insulin sensitivity. Reproduction 2013; 145:609-20. [PMID: 23613616 DOI: 10.1530/rep-12-0388] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Dietary protein restriction during pregnancy and lactation in rats impairs β-cell function and mass in neonates and leads to glucose intolerance in adult offspring. Maternal taurine (Tau) supplementation during pregnancy in rats restores β-cell function and mass in neonates, but its long-term effects are unclear. The prevention of postnatal catch-up growth has been suggested to improve glucose tolerance in adult offspring of low-protein (LP)-fed mothers. The objective of this study was to examine the relative contribution of β-cell dysfunction and insulin resistance to impaired glucose tolerance in 130-day-old rat offspring of LP-fed mothers and the effects of maternal Tau supplementation on β-cell function and insulin resistance in these offspring. Pregnant rats were fed i) control, ii) LP, and iii) LP+Tau diets during gestation and lactation. Offspring were given a control diet following weaning. A fourth group consisting of offspring of LP-fed mothers, maintained on a LP diet following weaning, was also studied (LP-all life). Insulin sensitivity in the offspring of LP-fed mothers was reduced in females but not in males. In both genders, LP exposure decreased β-cell function. Tau supplementation improved insulin sensitivity in females and β-cell function in males. The LP-all life diet improved β-cell function in males. We conclude that i) maternal Tau supplementation has persistent effects on improving glucose metabolism (β-cell function and insulin sensitivity) in adult rat offspring of LP-fed mothers and ii) increasing the amount of protein in the diet of offspring adapted to a LP diet after weaning may impair glucose metabolism (β-cell function) in a gender-specific manner.
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Affiliation(s)
- Christine Tang
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
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Koulajian K, Desai T, Liu GC, Ivovic A, Patterson JN, Tang C, El-Benna J, Joseph JW, Scholey JW, Giacca A. NADPH oxidase inhibition prevents beta cell dysfunction induced by prolonged elevation of oleate in rodents. Diabetologia 2013; 56:1078-87. [PMID: 23429921 PMCID: PMC3622749 DOI: 10.1007/s00125-013-2858-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Accepted: 01/21/2013] [Indexed: 12/16/2022]
Abstract
AIMS/HYPOTHESIS The activation of NADPH oxidase has been implicated in NEFA-induced beta cell dysfunction. However, the causal role of this activation in vivo remains unclear. Here, using rodents, we investigated whether pharmacological or genetic inhibition of NADPH oxidase could prevent NEFA-induced beta cell dysfunction in vivo. METHODS Normal rats were infused for 48 h with saline or oleate with or without the NADPH oxidase inhibitor apocynin. In addition, NADPH oxidase subunit p47(phox)-null mice and wild-type littermate controls were infused with saline or oleate for 48 h. This was followed by measurement of NADPH oxidase activity, reactive oxygen species (ROS) and superoxide imaging and assessment of beta cell function in isolated islets and hyperglycaemic clamps. RESULTS Oleate infusion in rats increased NADPH oxidase activity, consistent with increased total but not mitochondrial superoxide in islets and impaired beta cell function in isolated islets and during hyperglycaemic clamps. Co-infusion of apocynin with oleate normalised NADPH oxidase activity and total superoxide levels and prevented beta cell dysfunction. Similarly, 48 h NEFA elevation in wild-type mice increased total but not mitochondrial superoxide and impaired beta cell function in isolated islets. p47(phox)-null mice were protected against these effects when subjected to 48 h oleate infusion. Finally, oleate increased the levels of total ROS, in both models, whereas inhibition of NADPH oxidase prevented this increase, suggesting that NADPH oxidase is the main source of ROS in this model. CONCLUSIONS/INTERPRETATION These data show that NADPH-oxidase-derived cytosolic superoxide is increased in islets upon oleate infusion in vivo; and whole-body NADPH-oxidase inhibition decreases superoxide in concert with restoration of islet function.
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Affiliation(s)
- K. Koulajian
- Department of Physiology, University of Toronto, Medical Sciences Building, Room 3336-1 King’s College Circle, Toronto, ON Canada M5S 1A8
| | - T. Desai
- Department of Physiology, University of Toronto, Medical Sciences Building, Room 3336-1 King’s College Circle, Toronto, ON Canada M5S 1A8
| | - G. C. Liu
- Institute of Medical Sciences, University of Toronto, Toronto, ON Canada
| | - A. Ivovic
- Department of Physiology, University of Toronto, Medical Sciences Building, Room 3336-1 King’s College Circle, Toronto, ON Canada M5S 1A8
| | - J. N. Patterson
- School of Pharmacy, University of Waterloo, Waterloo, ON Canada
| | - C. Tang
- Department of Physiology, University of Toronto, Medical Sciences Building, Room 3336-1 King’s College Circle, Toronto, ON Canada M5S 1A8
| | - J. El-Benna
- Inserm, U773, Centre de Recherche Biomédicale Bichat Beaujon CRB3, Paris, France
- Université Paris 7 site Bichat, UMRS 773, Paris, France
| | - J. W. Joseph
- School of Pharmacy, University of Waterloo, Waterloo, ON Canada
| | - J. W. Scholey
- Institute of Medical Sciences, University of Toronto, Toronto, ON Canada
- Division of Nephrology, University of Toronto, Toronto, ON Canada
| | - A. Giacca
- Department of Physiology, University of Toronto, Medical Sciences Building, Room 3336-1 King’s College Circle, Toronto, ON Canada M5S 1A8
- Institute of Medical Sciences, University of Toronto, Toronto, ON Canada
- Department of Medicine, University of Toronto, Toronto, ON Canada
- Banting and Best Diabetes Centre, University of Toronto, Toronto, ON Canada
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44
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Karunakaran U, Park KG. A systematic review of oxidative stress and safety of antioxidants in diabetes: focus on islets and their defense. Diabetes Metab J 2013; 37:106-12. [PMID: 23641350 PMCID: PMC3638220 DOI: 10.4093/dmj.2013.37.2.106] [Citation(s) in RCA: 141] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
A growing body of evidence suggests that hyperglycemia-induced oxidative stress plays an important role in diabetic complications, especially β-cell dysfunction and failure. Under physiological conditions, reactive oxygen species serve as second messengers that facilitate signal transduction and gene expression in pancreatic β-cells. However, under pathological conditions, an imbalance in redox homeostasis leads to aberrant tissue damage and β-cell death due to a lack of antioxidant defense systems. Taking into account the vulnerability of islets to oxidative damage, induction of endogenous antioxidant enzymes or exogenous antioxidant administration has been proposed as a way to protect β-cells against diabetic insults. Here, we consider recent insights into how the redox response becomes deregulated under diabetic conditions, as well as the therapeutic benefits of antioxidants, which may provide clues for developing strategies aimed at the treatment or prevention of diabetes associated with β-cell failure.
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Affiliation(s)
- Udayakumar Karunakaran
- Departments of Internal Medicine, Biochemistry and Cell Biology, Research Institute of Aging and Metabolism and World Class University Program, Kyungpook National University School of Medicine, Daegu, Korea
| | - Keun-Gyu Park
- Departments of Internal Medicine, Biochemistry and Cell Biology, Research Institute of Aging and Metabolism and World Class University Program, Kyungpook National University School of Medicine, Daegu, Korea
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45
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Steinbrenner H, Hotze AL, Speckmann B, Pinto A, Sies H, Schott M, Ehlers M, Scherbaum WA, Schinner S. Localization and regulation of pancreatic selenoprotein P. J Mol Endocrinol 2013; 50:31-42. [PMID: 23125459 DOI: 10.1530/jme-12-0105] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Progressive loss of pancreatic β-cell mass is a crucial feature of type 2 diabetes mellitus. As β-cells express very low amounts of the antioxidant enzymes catalase and glutathione peroxidase (GPx), they appear to be particularly vulnerable to oxidative damage in the pathogenesis of diabetes. Here, we investigated the pancreatic expression pattern and regulation of selenoprotein P (Sepp1), which may serve as an additional antioxidant enzyme inside and outside of cells. Sepp1 was detected in rodent pancreas by immunofluorescence and real-time RT-PCR. Regulation of Sepp1 biosynthesis in INS-1 rat insulinoma cells was investigated by real-time RT-PCR, luciferase gene reporter assay, and immunoblotting. Sepp1 and Gpx1 gene expressions in rat pancreas were 58 and 22% respectively of the liver values. Pancreatic Sepp1 expression was restricted to the endocrine tissue, with Sepp1 being present in the α- and β-cells of mouse islets. In INS-1 insulinoma cells, Sepp1 expression was stimulated by the selenium compound sodium selenate and diminished in the presence of high glucose (16.7 vs 5 mM) concentrations. Sepp1 mRNA stability was also lowered at 16.7 mM glucose. Moreover, Sepp1 mRNA levels were decreased in isolated murine islets cultured in high-glucose (22 mM) medium compared with normal glucose (5.5 mM) medium. Pancreatic Sepp1 expression was elevated upon treatment of mice with the β-cell toxin streptozotocin. This study shows that pancreatic islets express relatively high levels of Sepp1 that may fulfill a function in antioxidant protection of β-cells. Downregulation of Sepp1 expression by high glucose might thus contribute to glucotoxicity in β-cells.
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Affiliation(s)
- Holger Steinbrenner
- Institute for Biochemistry and Molecular Biology I, Heinrich-Heine-University, Universitätsstrasse 1, D-40225 Düsseldorf, Germany
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46
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Tang C, Naassan AE, Chamson-Reig A, Koulajian K, Goh TT, Yoon F, Oprescu AI, Ghanim H, Lewis GF, Dandona P, Donath MY, Ehses JA, Arany E, Giacca A. Susceptibility to fatty acid-induced β-cell dysfunction is enhanced in prediabetic diabetes-prone biobreeding rats: a potential link between β-cell lipotoxicity and islet inflammation. Endocrinology 2013; 154:89-101. [PMID: 23150493 DOI: 10.1210/en.2012-1720] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
β-Cell lipotoxicity is thought to play an important role in the development of type 2 diabetes. However, no study has examined its role in type 1 diabetes, which could be clinically relevant for slow-onset type 1 diabetes. Reports of enhanced cytokine toxicity in fat-laden islets are consistent with the hypothesis that lipid and cytokine toxicity may be synergistic. Thus, β-cell lipotoxicity could be enhanced in models of autoimmune diabetes. To determine this, we examined the effects of prolonged free fatty acids elevation on β-cell secretory function in the prediabetic diabetes-prone BioBreeding (dp-BB) rat, its diabetes-resistant BioBreeding (dr-BB) control, and normal Wistar-Furth (WF) rats. Rats received a 48-h iv infusion of saline or Intralipid plus heparin (IH) (to elevate free fatty acid levels ~2-fold) followed by hyperglycemic clamp or islet secretion studies ex vivo. IH significantly decreased β-cell function, assessed both by the disposition index (insulin secretion corrected for IH-induced insulin resistance) and in isolated islets, in dp-BB, but not in dr-BB or WF, rats, and the effect of IH was inhibited by the antioxidant N-acetylcysteine. Furthermore, IH significantly increased islet cytokine mRNA and plasma cytokine levels (monocyte chemoattractant protein-1 and IL-10) in dp-BB, but not in dr-BB or WF, rats. All dp-BB rats had mononuclear infiltration of islets, which was absent in dr-BB and WF rats. In conclusion, the presence of insulitis was permissive for IH-induced β-cell dysfunction in the BB rat, which suggests a link between β-cell lipotoxicity and islet inflammation.
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Affiliation(s)
- Christine Tang
- Department of Physiology, University of Toronto, Room 3336, Medical Sciences Building, Toronto, Ontario, Canada M5S 1A8
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47
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Feng L, Zhu M, Zhang M, Jia X, Cheng X, Ding S, Zhu Q. Amelioration of compound 4,4'-diphenylmethane-bis(methyl)carbamate on high mobility group box1-mediated inflammation and oxidant stress responses in human umbilical vein endothelial cells via RAGE/ERK1/2/NF-κB pathway. Int Immunopharmacol 2012; 15:206-16. [PMID: 23219582 DOI: 10.1016/j.intimp.2012.11.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Revised: 11/22/2012] [Accepted: 11/23/2012] [Indexed: 01/25/2023]
Abstract
High mobility group box-1 (HMGB1), a secreted nuclear protein, acts as an inflammatory mediator and has been implicated in pathophysiological damage of diabetic vascular complications. A compound 4,4'-diphenylmethane-bis(methyl) carbamate (CM1) has a protective activity on advanced glycation end products (AGEs)-induced endothelial dysfunction in our previous study. The aim of this study was to investigate whether CM1 could attenuate HMGB1-induced endothelial dysfunction in human umbilical vein endothelial cells (HUVECs), and also elucidate the possible underlying mechanism. The pre-treatment of CM1 (10(-9)M) could inhibit significantly the migration of macrophages in co-incubation with HUVECs system. HMGB1 stimulated intercellular adhesion molecule-1 (ICAM-1), transforming growth factor-beta1 (TGF-β1) and receptor for advanced glycation end products (RAGE) protein expression in HUVECs, which were inhibited by pretreatment with CM1. Furthermore, it also reduced significantly reactive oxygen species (ROS) generation and inflammatory cytokine interleukin-6 (IL-6) level in co-incubation system. Immunofluorescence and Western blotting assays showed that CM1 could attenuate HMGB1-induced intracellular ERK1/2 and NF-kB activation in HUVECs. Our findings indicated that CM1 attenuated HMGB1-mediated endothelial activation by ameliorating inflammation and oxidant stress responses via RAGE/ERK1/2/NF-κB pathway.
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Affiliation(s)
- Liang Feng
- Key Laboratory of Delivery Systems of Chinese Materia Medica, Jiangsu Provincial Academy of Chinese Medicine, Jiangsu, Nanjing, 210028, China.
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48
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Abstract
In the endocrine fraction of the pancreas, the task of the beta-cell is to continuously and perfectly adjust insulin secretion to fluctuating blood glucose levels, thereby maintaining glycemia and nutrient homeostasis. This glucose sensing coupled to insulin exocytosis depends on transduction of metabolic signals into intracellular messengers recognized by the exocytotic machinery. Central to this metabolism-secretion coupling, mitochondrial signal transduction refers to both integration and generation of metabolic signals, connecting glucose sensing to insulin exocytosis. In response to a glucose rise, nucleotides and metabolites are generated by mitochondria and participate, together with cytosolic calcium, in the stimulation of insulin release. This review describes the role of mitochondria in metabolic signal transduction regulating insulin secretion.
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Affiliation(s)
- Pierre Maechler
- Department of Cell Physiology and Metabolism, University of Geneva Medical Centre, rue Michel-Servet 1, CH-1211 Geneva 4, Switzerland.
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49
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Bensellam M, Laybutt DR, Jonas JC. The molecular mechanisms of pancreatic β-cell glucotoxicity: recent findings and future research directions. Mol Cell Endocrinol 2012; 364:1-27. [PMID: 22885162 DOI: 10.1016/j.mce.2012.08.003] [Citation(s) in RCA: 208] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 07/11/2012] [Accepted: 08/01/2012] [Indexed: 02/06/2023]
Abstract
It is well established that regular physiological stimulation by glucose plays a crucial role in the maintenance of the β-cell differentiated phenotype. In contrast, prolonged or repeated exposure to elevated glucose concentrations both in vitro and in vivo exerts deleterious or toxic effects on the β-cell phenotype, a concept termed as glucotoxicity. Evidence indicates that the latter may greatly contribute to the pathogenesis of type 2 diabetes. Through the activation of several mechanisms and signaling pathways, high glucose levels exert deleterious effects on β-cell function and survival and thereby, lead to the worsening of the disease over time. While the role of high glucose-induced β-cell overstimulation, oxidative stress, excessive Unfolded Protein Response (UPR) activation, and loss of differentiation in the alteration of the β-cell phenotype is well ascertained, at least in vitro and in animal models of type 2 diabetes, the role of other mechanisms such as inflammation, O-GlcNacylation, PKC activation, and amyloidogenesis requires further confirmation. On the other hand, protein glycation is an emerging mechanism that may play an important role in the glucotoxic deterioration of the β-cell phenotype. Finally, our recent evidence suggests that hypoxia may also be a new mechanism of β-cell glucotoxicity. Deciphering these molecular mechanisms of β-cell glucotoxicity is a mandatory first step toward the development of therapeutic strategies to protect β-cells and improve the functional β-cell mass in type 2 diabetes.
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Affiliation(s)
- Mohammed Bensellam
- Université catholique de Louvain, Institut de recherche expérimentale et clinique, Pôle d'endocrinologie, diabète et nutrition, Brussels, Belgium
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50
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Peiris H, Raghupathi R, Jessup CF, Zanin MP, Mohanasundaram D, Mackenzie KD, Chataway T, Clarke JN, Brealey J, Coates PT, Pritchard MA, Keating DJ. Increased expression of the glucose-responsive gene, RCAN1, causes hypoinsulinemia, β-cell dysfunction, and diabetes. Endocrinology 2012; 153:5212-21. [PMID: 23011918 DOI: 10.1210/en.2011-2149] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
RCAN1 is a chromosome 21 gene that controls secretion in endocrine cells, regulates mitochondrial function, and is sensitive to oxidative stress. Regulator of calcineurin 1 (RCAN1) is also an endogenous inhibitor of the protein phosphatase calcineurin, the inhibition of which leads to hypoinsulinemia and diabetes in humans and mice. However, the presence or the role of RCAN1 in insulin-secreting β-cells and its potential role in the pathogenesis of diabetes is unknown. Hence, the aim of this study is to investigate the presence of RCAN1 in β-cells and identify its role in β-cell function. RCAN1 is expressed in mouse islets and in the cytosol of pancreatic β-cells. We find RCAN1 is a glucose-responsive gene with a 1.5-fold increase in expression observed in pancreatic islets in response to chronic hyperglycemia. The overexpression of the human RCAN1.1 isoform in mice under the regulation of its endogenous promoter causes diabetes, age-associated hyperglycemia, reduced glucose tolerance, hypoinsulinemia, loss of β-cells, reduced β-cell insulin secretion, aberrant mitochondrial reactive oxygen species production, and the down-regulation of key β-cell genes. Our data therefore identifies a novel molecular link between the overexpression of RCAN1 and β-cell dysfunction. The glucose-responsive nature of RCAN1 provides a potential mechanism of action associated with the β-cell dysfunction observed in diabetes.
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Affiliation(s)
- Heshan Peiris
- Flinders Medical Science and Technology and Centre for Neuroscience, Flinders University, Adelaide, Australia
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