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Ivovic A, Yung JHM, Oprescu AI, Vlavcheski F, Mori Y, Rahman SMN, Ye W, Eversley JA, Wheeler MB, Woo M, Tsiani E, Giacca A. β-Cell Insulin Resistance Plays a Causal Role in Fat-Induced β-Cell Dysfunction In Vitro and In Vivo. Endocrinology 2024; 165:bqae044. [PMID: 38578954 PMCID: PMC11033845 DOI: 10.1210/endocr/bqae044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 03/27/2024] [Accepted: 04/04/2024] [Indexed: 04/07/2024]
Abstract
In the classical insulin target tissues of liver, muscle, and adipose tissue, chronically elevated levels of free fatty acids (FFA) impair insulin signaling. Insulin signaling molecules are also present in β-cells where they play a role in β-cell function. Therefore, inhibition of the insulin/insulin-like growth factor 1 pathway may be involved in fat-induced β-cell dysfunction. To address the role of β-cell insulin resistance in FFA-induced β-cell dysfunction we co-infused bisperoxovanadate (BPV) with oleate or olive oil for 48 hours in rats. BPV, a tyrosine phosphatase inhibitor, acts as an insulin mimetic and is devoid of any antioxidant effect that could prevent β-cell dysfunction, unlike most insulin sensitizers. Following fat infusion, rats either underwent hyperglycemic clamps for assessment of β-cell function in vivo or islets were isolated for ex vivo assessment of glucose-stimulated insulin secretion (GSIS). We also incubated islets with oleate or palmitate and BPV for in vitro assessment of GSIS and Akt (protein kinase B) phosphorylation. Next, mice with β-cell specific deletion of PTEN (phosphatase and tensin homolog; negative regulator of insulin signaling) and littermate controls were infused with oleate for 48 hours, followed by hyperglycemic clamps or ex vivo evaluation of GSIS. In rat experiments, BPV protected against fat-induced impairment of β-cell function in vivo, ex vivo, and in vitro. In mice, β-cell specific deletion of PTEN protected against oleate-induced β-cell dysfunction in vivo and ex vivo. These data support the hypothesis that β-cell insulin resistance plays a causal role in FFA-induced β-cell dysfunction.
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Affiliation(s)
- Aleksandar Ivovic
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Justin Hou Ming Yung
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Andrei I Oprescu
- Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Filip Vlavcheski
- Department of Health Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada
| | - Yusaku Mori
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada
- Division of Diabetes, Metabolism, and Endocrinology, Anti-Glycation Research Section, Department of Medicine, Showa University School of Medicine, Shinagawa, Tokyo 142-8555, Japan
| | - S M Niazur Rahman
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Wenyue Ye
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Judith A Eversley
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Michael B Wheeler
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Minna Woo
- Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada
- Toronto General Hospital Research Institute, University Health Network, University of Toronto, Toronto, ON M5G 2C4, Canada
- Division of Endocrinology, Department of Medicine, University Health Network, University of Toronto, Toronto, ON M5G 2C4, Canada
- Department of Medicine, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada
- Banting and Best Diabetes Centre, University of Toronto, Toronto, ON M5G 2C4, Canada
| | - Evangelia Tsiani
- Department of Health Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada
| | - Adria Giacca
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada
- Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada
- Department of Medicine, Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8, Canada
- Banting and Best Diabetes Centre, University of Toronto, Toronto, ON M5G 2C4, Canada
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Massimino M, Monea G, Marinaro G, Rubino M, Mancuso E, Mannino GC, Andreozzi F. The Triglycerides and Glucose (TyG) Index Is Associated with 1-Hour Glucose Levels during an OGTT. Int J Environ Res Public Health 2022; 20:787. [PMID: 36613109 PMCID: PMC9819897 DOI: 10.3390/ijerph20010787] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 12/20/2022] [Accepted: 12/21/2022] [Indexed: 06/17/2023]
Abstract
BACKGROUND AND OBJECTIVES Among individuals with normal glucose tolerance (NGT), subjects with high levels of plasma glucose (≥155 mg/dL) at sixty minutes during an oral glucose tolerance test (1h-OGTT) are at an increased risk of developing type 2 diabetes. We investigated the association between the triglycerides and glucose (TyG) index, a novel marker of insulin resistance, with 1h-OGTT glucose plasma concentrations. MATERIAL AND METHODS 1474 non-diabetic Caucasian subjects underwent a 75 g OGTT and were divided into two groups according to the cutoff 1h-OGTT plasma glucose < 155 mg/dL (NGT-1h-low) and ≥ 155 mg/dL (NGT-1h-high). The TyG index was calculated as ln [fasting triglycerides (milligrams per deciliter) × fasting blood glucose (milligrams per deciliter)/2]. Multivariable linear and logistic regression analyses were used to establish the contribution of the TyG index to the variability of 1h-OGTT glucose, and how the former affected the risk of being NGT-1h-high. RESULTS 1004 individuals were NGT-1h-low and 470 were NGT-1h-high. The TyG index was higher for NGT-1h-high (p = 0.001) individuals, and it was an independent factor influencing 1h-OGTT glycemia (β = 0.191, p < 0.001) after correcting for age, sex, and BMI. The TyG index was the strongest marker associated with the risk of being NGT-1h-high (OR = 1.703, CI 95% 1.34-2.17, p < 0.001) when compared with FPG (OR = 1.054, CI 95% 1.04-1.07, p < 0.001) and the HOMA-IR (OR = 1.156, CI 95% 1.08-1.23, p < 0.001). CONCLUSIONS Our study demonstrated that the TyG index, an efficient and cost-effective marker of insulin resistance, is associated with the variability of early post-challenge glucose levels and is an independent marker of being NGT-1h-high.
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Affiliation(s)
- Mattia Massimino
- Department of Medical and Surgical Sciences, University Magna Graecia of Catanzaro, 88100 Catanzaro, Italy
| | - Giuseppe Monea
- Department of Medical and Surgical Sciences, University Magna Graecia of Catanzaro, 88100 Catanzaro, Italy
| | - Giuseppe Marinaro
- Department of Medical and Surgical Sciences, University Magna Graecia of Catanzaro, 88100 Catanzaro, Italy
| | - Mariangela Rubino
- Department of Medical and Surgical Sciences, University Magna Graecia of Catanzaro, 88100 Catanzaro, Italy
| | - Elettra Mancuso
- Department of Medical and Surgical Sciences, University Magna Graecia of Catanzaro, 88100 Catanzaro, Italy
| | - Gaia Chiara Mannino
- Department of Medical and Surgical Sciences, University Magna Graecia of Catanzaro, 88100 Catanzaro, Italy
| | - Francesco Andreozzi
- Department of Medical and Surgical Sciences, University Magna Graecia of Catanzaro, 88100 Catanzaro, Italy
- Research Center for the Prevention and Treatment of Metabolic Diseases (CR METDIS), University Magna Grecia of Catanzaro, 88100 Catanzaro, Italy
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Petry SF, Römer A, Rawat D, Brunner L, Lerch N, Zhou M, Grewal R, Sharifpanah F, Sauer H, Eckert GP, Linn T. Loss and Recovery of Glutaredoxin 5 Is Inducible by Diet in a Murine Model of Diabesity and Mediated by Free Fatty Acids In Vitro. Antioxidants (Basel) 2022; 11:antiox11040788. [PMID: 35453472 PMCID: PMC9025089 DOI: 10.3390/antiox11040788] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Revised: 03/24/2022] [Accepted: 04/14/2022] [Indexed: 02/05/2023] Open
Abstract
Free fatty acids (FFA), hyperglycemia, and inflammatory cytokines are major mediators of β-cell toxicity in type 2 diabetes mellitus, impairing mitochondrial metabolism. Glutaredoxin 5 (Glrx5) is a mitochondrial protein involved in the assembly of iron–sulfur clusters required for complexes of the respiratory chain. We have provided evidence that islet cells are deprived of Glrx5, correlating with impaired insulin secretion during diabetes in genetically obese mice. In this study, we induced diabesity in C57BL/6J mice in vivo by feeding the mice a high-fat diet (HFD) and modelled the diabetic metabolism in MIN6 cells through exposure to FFA, glucose, or inflammatory cytokines in vitro. qRT-PCR, ELISA, immunohisto-/cytochemistry, bioluminescence, and respirometry were employed to study Glrx5, insulin secretion, and mitochondrial biomarkers. The HFD induced a depletion of islet Glrx5 concomitant with an obese phenotype, elevated FFA in serum and reactive oxygen species in islets, and impaired glucose tolerance. Exposure of MIN6 cells to FFA led to a loss of Glrx5 in vitro. The FFA-induced depletion of Glrx5 coincided with significantly altered mitochondrial biomarkers. In summary, we provide evidence that Glrx5 is regulated by FFA in type 2 diabetes mellitus and is linked to mitochondrial dysfunction and blunted insulin secretion.
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Affiliation(s)
- Sebastian Friedrich Petry
- Clinical Research Unit, Medical Clinic and Polyclinic III, Center of Internal Medicine, Justus Liebig University, 35392 Giessen, Germany; (A.R.); (D.R.); (L.B.); (N.L.); (M.Z.); (T.L.)
- Correspondence: ; Tel.: +49-641-985-57010
| | - Axel Römer
- Clinical Research Unit, Medical Clinic and Polyclinic III, Center of Internal Medicine, Justus Liebig University, 35392 Giessen, Germany; (A.R.); (D.R.); (L.B.); (N.L.); (M.Z.); (T.L.)
| | - Divya Rawat
- Clinical Research Unit, Medical Clinic and Polyclinic III, Center of Internal Medicine, Justus Liebig University, 35392 Giessen, Germany; (A.R.); (D.R.); (L.B.); (N.L.); (M.Z.); (T.L.)
| | - Lara Brunner
- Clinical Research Unit, Medical Clinic and Polyclinic III, Center of Internal Medicine, Justus Liebig University, 35392 Giessen, Germany; (A.R.); (D.R.); (L.B.); (N.L.); (M.Z.); (T.L.)
| | - Nina Lerch
- Clinical Research Unit, Medical Clinic and Polyclinic III, Center of Internal Medicine, Justus Liebig University, 35392 Giessen, Germany; (A.R.); (D.R.); (L.B.); (N.L.); (M.Z.); (T.L.)
| | - Mengmeng Zhou
- Clinical Research Unit, Medical Clinic and Polyclinic III, Center of Internal Medicine, Justus Liebig University, 35392 Giessen, Germany; (A.R.); (D.R.); (L.B.); (N.L.); (M.Z.); (T.L.)
| | - Rekha Grewal
- Laboratory for Nutrition in Prevention & Therapy, Department of Nutritional Sciences, Justus Liebig University, 35392 Giessen, Germany; (R.G.); (G.P.E.)
| | - Fatemeh Sharifpanah
- Faculty of Medicine, Philipps University, 35037 Marburg, Germany;
- Cyntegrity Germany GmbH, 60438 Frankfurt, Germany
| | - Heinrich Sauer
- Department of Physiology, Faculty of Medicine, Justus Liebig University, 35392 Giessen, Germany;
| | - Gunter Peter Eckert
- Laboratory for Nutrition in Prevention & Therapy, Department of Nutritional Sciences, Justus Liebig University, 35392 Giessen, Germany; (R.G.); (G.P.E.)
| | - Thomas Linn
- Clinical Research Unit, Medical Clinic and Polyclinic III, Center of Internal Medicine, Justus Liebig University, 35392 Giessen, Germany; (A.R.); (D.R.); (L.B.); (N.L.); (M.Z.); (T.L.)
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Zhao YF. Free fatty acid receptors in the endocrine regulation of glucose metabolism: Insight from gastrointestinal-pancreatic-adipose interactions. Front Endocrinol (Lausanne) 2022; 13:956277. [PMID: 36246919 PMCID: PMC9554507 DOI: 10.3389/fendo.2022.956277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 09/14/2022] [Indexed: 11/25/2022] Open
Abstract
Glucose metabolism is primarily controlled by pancreatic hormones, with the coordinated assistance of the hormones from gastrointestine and adipose tissue. Studies have unfolded a sophisticated hormonal gastrointestinal-pancreatic-adipose interaction network, which essentially maintains glucose homeostasis in response to the changes in substrates and nutrients. Free fatty acids (FFAs) are the important substrates that are involved in glucose metabolism. FFAs are able to activate the G-protein coupled membrane receptors including GPR40, GPR120, GPR41 and GPR43, which are specifically expressed in pancreatic islet cells, enteroendocrine cells as well as adipocytes. The activation of FFA receptors regulates the secretion of hormones from pancreas, gastrointestine and adipose tissue to influence glucose metabolism. This review presents the effects of the FFA receptors on glucose metabolism via the hormonal gastrointestinal-pancreatic-adipose interactions and the underlying intracellular mechanisms. Furthermore, the development of therapeutic drugs targeting FFA receptors for the treatment of abnormal glucose metabolism such as type 2 diabetes mellitus is summarized.
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Reed J, Bain S, Kanamarlapudi V. A Review of Current Trends with Type 2 Diabetes Epidemiology, Aetiology, Pathogenesis, Treatments and Future Perspectives. Diabetes Metab Syndr Obes 2021; 14:3567-3602. [PMID: 34413662 PMCID: PMC8369920 DOI: 10.2147/dmso.s319895] [Citation(s) in RCA: 102] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 07/09/2021] [Indexed: 12/13/2022] Open
Abstract
Type 2 diabetes (T2D), which has currently become a global pandemic, is a metabolic disease largely characterised by impaired insulin secretion and action. Significant progress has been made in understanding T2D aetiology and pathogenesis, which is discussed in this review. Extrapancreatic pathology is also summarised, which demonstrates the highly multifactorial nature of T2D. Glucagon-like peptide (GLP)-1 is an incretin hormone responsible for augmenting insulin secretion from pancreatic beta-cells during the postprandial period. Given that native GLP-1 has a very short half-life, GLP-1 mimetics with a much longer half-life have been developed, which are currently an effective treatment option for T2D by enhancing insulin secretion in patients. Interestingly, there is continual emerging evidence that these therapies alleviate some of the post-diagnosis complications of T2D. Additionally, these therapies have been shown to induce weight loss in patients, suggesting they could be an alternative to bariatric surgery, a procedure associated with numerous complications. Current GLP-1-based therapies all act as orthosteric agonists for the GLP-1 receptor (GLP-1R). Interestingly, it has emerged that GLP-1R also has allosteric binding sites and agonists have been developed for these sites to test their therapeutic potential. Recent studies have also demonstrated the potential of bi- and tri-agonists, which target multiple hormonal receptors including GLP-1R, to more effectively treat T2D. Improved understanding of T2D aetiology/pathogenesis, coupled with the further elucidation of both GLP-1 activity/targets and GLP-1R mechanisms of activation via different agonists, will likely provide better insight into the therapeutic potential of GLP-1-based therapies to treat T2D.
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Affiliation(s)
- Josh Reed
- Institute of Life Science 1, Medical School, Swansea University, Swansea, SA2 8PP, UK
| | - Stephen Bain
- Institute of Life Science 1, Medical School, Swansea University, Swansea, SA2 8PP, UK
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Meyer J, Kononov SU, Grindler S, Tröscher-Mußotter J, Alaedin MT, Frahm J, Hüther L, Kluess J, Kersten S, von Soosten D, Meyer U, Most E, Eder K, Sauerwein H, Seifert J, Huber K, Wegerich A, Rehage J, Dänicke S. Dietary l-carnitine Supplementation Modifies the Lipopolysaccharide-Induced Acute Phase Reaction in Dairy Cows. Animals (Basel) 2021; 11:ani11010136. [PMID: 33435209 PMCID: PMC7828073 DOI: 10.3390/ani11010136] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 01/08/2021] [Indexed: 12/28/2022] Open
Abstract
l-carnitine plays an important role in energy metabolism through supporting the transport of activated fatty acids to the subcellular site of β-oxidation. An acute phase reaction (APR) is known as an energy consuming process. Lipopolysaccharides (LPS) are often used in animal models to study intervention measures during innate immune responses such as APR. Thus, the aim of the study was to investigate the effects of dietary l-carnitine supplementation during an LPS-induced APR in mid-lactating German Holstein cows. Animals were assigned to a control (CON, n = 26) or l-carnitine group (CAR, n = 27, 25 g rumen-protected l-carnitine/cow/d) and received an intravenous injection of LPS (0.5 μg/kg body weight) at day 111 post-partum. Blood samples were collected from day 1 pre-injection until day 14 post-injection (pi). From 0.5 h pi until 72 h pi blood samplings and clinical examinations were performed in short intervals. Clinical signs of the APR were not altered in group CAR except rumen motility which increased at a lower level compared to the CON group after a period of atonia. Group CAR maintained a higher insulin level compared to group CON even up to 72 h pi which might support glucose utilization following an APR.
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Affiliation(s)
- Jennifer Meyer
- Institute of Animal Nutrition, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Bundesallee 37, 38116 Braunschweig, Germany; (J.M.); (S.U.K.); (L.H.); (J.K.); (S.K.); (D.v.S.); (U.M.); (S.D.)
| | - Susanne Ursula Kononov
- Institute of Animal Nutrition, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Bundesallee 37, 38116 Braunschweig, Germany; (J.M.); (S.U.K.); (L.H.); (J.K.); (S.K.); (D.v.S.); (U.M.); (S.D.)
- Institute of Animal Science, Functional Anatomy of Livestock, University of Hohenheim, Fruwirthstraße 35, 70593 Stuttgart, Germany; (S.G.); (K.H.)
| | - Sandra Grindler
- Institute of Animal Science, Functional Anatomy of Livestock, University of Hohenheim, Fruwirthstraße 35, 70593 Stuttgart, Germany; (S.G.); (K.H.)
| | - Johanna Tröscher-Mußotter
- Institute of Animal Science, Functional Microbiology of Livestock, University of Hohenheim, Emil-Wolff-Str. 8, 70593 Stuttgart, Germany; (J.T.-M.); (J.S.)
| | - Mohamad Taher Alaedin
- Institute for Animal Science, Physiology and Hygiene, Rheinische Friedrich-Wilhelms-Universität Bonn, Katzenburgweg 7-9, 53115 Bonn, Germany; (M.T.A.); (H.S.)
| | - Jana Frahm
- Institute of Animal Nutrition, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Bundesallee 37, 38116 Braunschweig, Germany; (J.M.); (S.U.K.); (L.H.); (J.K.); (S.K.); (D.v.S.); (U.M.); (S.D.)
- Correspondence: ; Tel.: +49-531-58044-142
| | - Liane Hüther
- Institute of Animal Nutrition, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Bundesallee 37, 38116 Braunschweig, Germany; (J.M.); (S.U.K.); (L.H.); (J.K.); (S.K.); (D.v.S.); (U.M.); (S.D.)
| | - Jeannette Kluess
- Institute of Animal Nutrition, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Bundesallee 37, 38116 Braunschweig, Germany; (J.M.); (S.U.K.); (L.H.); (J.K.); (S.K.); (D.v.S.); (U.M.); (S.D.)
| | - Susanne Kersten
- Institute of Animal Nutrition, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Bundesallee 37, 38116 Braunschweig, Germany; (J.M.); (S.U.K.); (L.H.); (J.K.); (S.K.); (D.v.S.); (U.M.); (S.D.)
| | - Dirk von Soosten
- Institute of Animal Nutrition, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Bundesallee 37, 38116 Braunschweig, Germany; (J.M.); (S.U.K.); (L.H.); (J.K.); (S.K.); (D.v.S.); (U.M.); (S.D.)
| | - Ulrich Meyer
- Institute of Animal Nutrition, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Bundesallee 37, 38116 Braunschweig, Germany; (J.M.); (S.U.K.); (L.H.); (J.K.); (S.K.); (D.v.S.); (U.M.); (S.D.)
| | - Erika Most
- Institute of Animal Nutrition and Nutrition Physiology, Justus-Liebig-Universität Gießen, Heinrich-Buff-Ring 26-32, 35392 Gießen, Germany; (E.M.); (K.E.)
| | - Klaus Eder
- Institute of Animal Nutrition and Nutrition Physiology, Justus-Liebig-Universität Gießen, Heinrich-Buff-Ring 26-32, 35392 Gießen, Germany; (E.M.); (K.E.)
| | - Helga Sauerwein
- Institute for Animal Science, Physiology and Hygiene, Rheinische Friedrich-Wilhelms-Universität Bonn, Katzenburgweg 7-9, 53115 Bonn, Germany; (M.T.A.); (H.S.)
| | - Jana Seifert
- Institute of Animal Science, Functional Microbiology of Livestock, University of Hohenheim, Emil-Wolff-Str. 8, 70593 Stuttgart, Germany; (J.T.-M.); (J.S.)
| | - Korinna Huber
- Institute of Animal Science, Functional Anatomy of Livestock, University of Hohenheim, Fruwirthstraße 35, 70593 Stuttgart, Germany; (S.G.); (K.H.)
| | - Anja Wegerich
- Clinic for Cattle, University of Veterinary Medicine Hannover, Foundation, Bischofsholer Damm 15, 30173 Hannover, Germany; (A.W.); (J.R.)
| | - Jürgen Rehage
- Clinic for Cattle, University of Veterinary Medicine Hannover, Foundation, Bischofsholer Damm 15, 30173 Hannover, Germany; (A.W.); (J.R.)
| | - Sven Dänicke
- Institute of Animal Nutrition, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Bundesallee 37, 38116 Braunschweig, Germany; (J.M.); (S.U.K.); (L.H.); (J.K.); (S.K.); (D.v.S.); (U.M.); (S.D.)
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Li X, Li G, Cheng T, Liu J, Song G, Ma H. Association between triglyceride-glucose index and risk of incident diabetes: a secondary analysis based on a Chinese cohort study : TyG index and incident diabetes. Lipids Health Dis 2020; 19:236. [PMID: 33161902 PMCID: PMC7649000 DOI: 10.1186/s12944-020-01403-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 10/14/2020] [Indexed: 01/29/2023] Open
Abstract
Background Recent studies have suggested the triglyceride-glucose index (TyG index) may serve as a suitable substitute for insulin resistance. However, evidence for the relationship between TyG index and risk of diabetes remains limited. This study sought to explore the association of baseline TyG index with risk of developing diabetes in Chinese adults. Methods This retrospective cohort study was conducted using data from the health screening program in China. A total of 201,298 non-diabetic individuals were included. TyG index was calculated as Ln [fasting plasma glucose (mg/dL) × fasting triglyceride level (mg/dL) / 2]. Diabetes was defined as fasting plasma glucose ≥126 mg/dL and/or self-reported diabetes. Cox proportion-hazard model was employed to evaluate the independent impact of baseline TyG index on future diabetes risk. Sensitivity and subgroup analyses were implemented to verify the reliability of results. Notably, data were downloaded from the DATADRYAD website, and used only for secondary analyses. Results During an average follow-up of 3.12 years, among 201,298 individuals aged ≥20 years, 3389 subjects developed diabetes. After adjusting for potential confounders, elevated TyG index were independently correlated with greater risk of incident diabetes (hazard ratio (HR), 3.34; 95% confidence interval (CI), 3.11–3.60). Compared with the lowest quartile (Q1), increasing TyG index (Q2, Q3, and Q4) was related to increased HR estimates of incident diabetes [HR (95% CI), 1.83 (1.49–2.26); 3.29 (2.70–4.01), and 6.26 (5.15–7.60), respectively]. Moreover, a nonlinear relationship was observed between TyG index and risk of diabetes and the slope of the curve increased accompanying the rise of TyG index. Subgroup analysis revealed the positive association was stronger among subjects with age < 40 years, body mass index ≥18.5 kg/m2 and < 24 kg/m2, or systolic blood pressure < 140 mmHg, or in females. Conclusions Elevated TyG index is independently correlated with increased risk of incident diabetes in Chinese adults, indicating it may represent a reliable predictor of diabetes in high-risk populations. Supplementary information Supplementary information accompanies this paper at 10.1186/s12944-020-01403-7.
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Affiliation(s)
- Xiaoli Li
- Department of Internal Medicine, Hebei Medical University, Shijiazhuang, 050017, Hebei, China.,Department of Endocrinology and Metabolic Diseases, Hebei General Hospital, Shijiazhuang, 050051, Hebei, China
| | - Guilong Li
- Department of Cardiology, Xingtai Third Hospital, Xingtai, 054000, Hebei, China
| | - Tiantian Cheng
- Department of Endocrinology and Metabolic Diseases, Hebei General Hospital, Shijiazhuang, 050051, Hebei, China.,Clinical Medical College, North China University of Science and Technology, Tangshan, 063210, Hebei, China
| | - Jing Liu
- Department of Endocrinology and Metabolic Diseases, Hebei General Hospital, Shijiazhuang, 050051, Hebei, China
| | - Guangyao Song
- Department of Internal Medicine, Hebei Medical University, Shijiazhuang, 050017, Hebei, China.,Department of Endocrinology and Metabolic Diseases, Hebei General Hospital, Shijiazhuang, 050051, Hebei, China
| | - Huijuan Ma
- Department of Internal Medicine, Hebei Medical University, Shijiazhuang, 050017, Hebei, China. .,Hebei Key Laboratory of Metabolic Diseases, Hebei General Hospital, Shijiazhuang, 050051, Hebei, China.
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Ezeh U, Chen IYD, Chen YH, Azziz R. Adipocyte Insulin Resistance in PCOS: Relationship With GLUT-4 Expression and Whole-Body Glucose Disposal and β-Cell Function. J Clin Endocrinol Metab 2020; 105:5834379. [PMID: 32382742 PMCID: PMC7274487 DOI: 10.1210/clinem/dgaa235] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 04/29/2020] [Indexed: 01/16/2023]
Abstract
CONTEXT Impaired sensitivity to the antilipolytic action of insulin in adipose tissue (AT) may play a role in determining metabolic dysfunction in polycystic ovary syndrome (PCOS). OBJECTIVES To test the hypothesis that insulin resistance (IR) in AT is associated with whole-body insulin sensitivity and β-cell function in PCOS. RESEARCH DESIGN AND SETTING Prospective cross-sectional study. METHODS Eighteen participants with PCOS and 18-matched control participants underwent a modified frequently sampled intravenous glucose tolerance test (mFSIVGTT); subgroups underwent single-slice computed tomography scans determining AT distribution and adipocyte glucose transporter type 4 (GLUT-4) expression. MAIN OUTCOME MEASURES IR in AT in basal (by the adipose insulin resistance index [Adipo-IR]) and dynamic (mFSIVGTT-derived indices of insulin-mediated nonesterified fatty acids [NEFA] suppression [NEFAnadir, TIMEnadir, and %NEFAsupp]) states; whole-body insulin-mediated glucose uptake and insulin secretion in basal (by homeostatic model assessment [HOMA]-IR and HOMA-β%) and dynamic (mFSIVGTT-derived insulin sensitivity index [Si], acute insulin response to glucose [AIRg], and disposition index [Di]) states. RESULTS Participants with PCOS had higher HOMA-IR and HOMA-β%, lower Si and Di, higher longer TIMEnadir, higher Adipo-IR and NEFAnadir, and a trend toward lower GLUT-4, than the control group participants. Adipo-IR was associated with dynamic state IR in AT (NEFAnadir TIMEnadir, and %NEFAsupp), but only in PCOS, and with HOMA-IR and HOMA-β% in both groups. NEFAnadir and TIMEnadir were negatively and %NEFAsupp positively associated with Si only in PCOS, but not with AIRg and Di, or GLUT-4 expression. CONCLUSION Women with PCOS demonstrated increased IR in AT, which is closely associated with whole-body IR but not with dynamic state β-cell function or adipocyte GLUT-4 gene expression.
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Affiliation(s)
- Uche Ezeh
- Department of Obstetrics and Gynecology, Stanford Healthcare-ValleyCare Hospital, Pleasanton, California
- Department of Obstetrics & Gynecology and Center for Androgen-Related Disorders, Cedars-Sinai Medical Center, Los Angeles, California
- Department of Obstetrics & Gynecology, Medical College of Georgia, Augusta University, Augusta, Georgia
| | - Ida Y-D Chen
- Department of Obstetrics & Gynecology and Center for Androgen-Related Disorders, Cedars-Sinai Medical Center, Los Angeles, California
- Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California
- Institute for Translational Genomics and Population Sciences, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California
| | - Yen-Hao Chen
- Department of Obstetrics & Gynecology and Center for Androgen-Related Disorders, Cedars-Sinai Medical Center, Los Angeles, California
- Department of Obstetrics & Gynecology, Medical College of Georgia, Augusta University, Augusta, Georgia
| | - Ricardo Azziz
- Department of Obstetrics & Gynecology and Center for Androgen-Related Disorders, Cedars-Sinai Medical Center, Los Angeles, California
- Department of Obstetrics & Gynecology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California
- Department of Health Policy, Management and Behavior, School of Public Health, University at Albany, SUNY, Albany, New York
- Department of Obstetrics & Gynecology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama
- Correspondence and Reprint Requests: Ricardo Azziz, American Society for Reproductive Medicine, 1209 Montgomery Hwy, Birmingham, AL. E-mail:
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9
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XING QC, LIU X, LI W, CHEN YZ, CHEN J. Sangguayin preparation prevents palmitate-induced apoptosis by suppressing endoplasmic reticulum stress and autophagy in db/db mice and MIN6 pancreatic β-cells. Chin J Nat Med 2020; 18:472-480. [DOI: 10.1016/s1875-5364(20)30054-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Indexed: 12/24/2022]
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10
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Ye G, Gao H, Huang Q, Lin Y, Liao X, Zhang H, Yang BC. Metabolomic Characterization of Metabolic Disturbances in the Extracellular Microenvironment of Oleate-Treated Macrophages Using Gas Chromatography–Mass Spectrometry. ANAL LETT 2020. [DOI: 10.1080/00032719.2020.1750623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Guozhu Ye
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, China
| | - Han Gao
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Qiansheng Huang
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, China
| | - Yi Lin
- State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen, China
| | - Xu Liao
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, China
| | - Han Zhang
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, China
| | - Bi-cheng Yang
- Jiangxi Provincial Maternal and Child Health Hospital, Nanchang, Jiangxi, China
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Abstract
Reduction of β-cell mass and function is central to the pathogenesis of type 2 diabetes. The terms glucotoxicity, lipotoxicity, and glucolipotoxicity are used to describe potentially responsible processes. The premise is that chronically elevated glucose levels are toxic to β-cells, that elevated lipid levels in the form of circulating free fatty acids (FFA) also have toxic effects, and that the combination of the two, glucolipotoxicity, is particularly harmful. Much work has shown that high concentrations of FFA can be very damaging to β-cells when used for in vitro experiments, and when infused in large amounts in humans and rodents they produce suppression of insulin secretion. The purpose of this Perspective is to raise doubts about whether the FFA levels found in real-life situations are ever high enough to cause problems. Evidence supporting the importance of glucotoxicity is strong because there is such a tight correlation between defective insulin secretion and rising glucose levels. However, there is virtually no convincing evidence that the alterations in FFA levels occurring during progression to diabetes are pathogenic. Thus, the terms lipotoxicity and glucolipotoxicity should be used with great caution, if at all, because evidence supporting their importance has not yet emerged.
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Affiliation(s)
- Gordon C Weir
- Section on Islet Cell and Regenerative Biology, Joslin Diabetes Center, Harvard Medical School, Boston, MA
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12
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Lytrivi M, Castell AL, Poitout V, Cnop M. Recent Insights Into Mechanisms of β-Cell Lipo- and Glucolipotoxicity in Type 2 Diabetes. J Mol Biol 2019; 432:1514-1534. [PMID: 31628942 DOI: 10.1016/j.jmb.2019.09.016] [Citation(s) in RCA: 184] [Impact Index Per Article: 36.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2019] [Revised: 09/15/2019] [Accepted: 09/16/2019] [Indexed: 12/24/2022]
Abstract
The deleterious effects of chronically elevated free fatty acid (FFA) levels on glucose homeostasis are referred to as lipotoxicity, and the concurrent exposure to high glucose may cause synergistic glucolipotoxicity. Lipo- and glucolipotoxicity have been studied for over 25 years. Here, we review the current evidence supporting the role of pancreatic β-cell lipo- and glucolipotoxicity in type 2 diabetes (T2D), including lipid-based interventions in humans, prospective epidemiological studies, and human genetic findings. In addition to total FFA quantity, the quality of FFAs (saturation and chain length) is a key determinant of lipotoxicity. We discuss in vitro and in vivo experimental models to investigate lipo- and glucolipotoxicity in β-cells and describe experimental pitfalls. Lipo- and glucolipotoxicity adversely affect many steps of the insulin production and secretion process. The molecular mechanisms underpinning lipo- and glucolipotoxic β-cell dysfunction and death comprise endoplasmic reticulum stress, oxidative stress and mitochondrial dysfunction, impaired autophagy, and inflammation. Crosstalk between these stress pathways exists at multiple levels and may aggravate β-cell lipo- and glucolipotoxicity. Lipo- and glucolipotoxicity are therapeutic targets as several drugs impact the underlying stress responses in β-cells, potentially contributing to their glucose-lowering effects in T2D.
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Affiliation(s)
- Maria Lytrivi
- ULB Center for Diabetes Research, Medical Faculty, Université Libre de Bruxelles, Brussels, Belgium; Division of Endocrinology, Erasmus Hospital, Université Libre de Bruxelles, Brussels, Belgium
| | - Anne-Laure Castell
- CRCHUM, Montréal, QC, Canada; Department of Medicine, Université de Montréal, Montréal, QC, Canada
| | - Vincent Poitout
- CRCHUM, Montréal, QC, Canada; Department of Medicine, Université de Montréal, Montréal, QC, Canada.
| | - Miriam Cnop
- ULB Center for Diabetes Research, Medical Faculty, Université Libre de Bruxelles, Brussels, Belgium; Division of Endocrinology, Erasmus Hospital, Université Libre de Bruxelles, Brussels, Belgium.
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Li Z, Zhou M, Cai Z, Liu H, Zhong W, Hao Q, Cheng D, Hu X, Hou J, Xu P, Xue Y, Zhou Y, Xu T. RNA-binding protein DDX1 is responsible for fatty acid-mediated repression of insulin translation. Nucleic Acids Res 2019; 46:12052-12066. [PMID: 30295850 PMCID: PMC6294501 DOI: 10.1093/nar/gky867] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2018] [Accepted: 09/14/2018] [Indexed: 01/13/2023] Open
Abstract
The molecular mechanism in pancreatic β cells underlying hyperlipidemia and insulin insufficiency remains unclear. Here, we find that the fatty acid-induced decrease in insulin levels occurs due to a decrease in insulin translation. Since regulation at the translational level is generally mediated through RNA-binding proteins, using RNA antisense purification coupled with mass spectrometry, we identify a novel insulin mRNA-binding protein, namely, DDX1, that is sensitive to palmitate treatment. Notably, the knockdown or overexpression of DDX1 affects insulin translation, and the knockdown of DDX1 eliminates the palmitate-induced repression of insulin translation. Molecular mechanism studies show that palmitate treatment causes DDX1 phosphorylation at S295 and dissociates DDX1 from insulin mRNA, thereby leading to the suppression of insulin translation. In addition, DDX1 may interact with the translation initiation factors eIF3A and eIF4B to regulate translation. In high-fat diet mice, the inhibition of insulin translation happens at an early prediabetic stage before the elevation of glucose levels. We speculate that the DDX1-mediated repression of insulin translation worsens the situation of insulin resistance and contributes to the elevation of blood glucose levels in obese animals.
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Affiliation(s)
- Zonghong Li
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics & University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China.,Jilin Province Key Laboratory on Chemistry and Biology of Changbai Mountain Natural Drugs, School of Life Sciences, Northeast Normal University, Changchun 130024, China
| | - Maoge Zhou
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics & University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China
| | - Zhaokui Cai
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Hongyang Liu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics & University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China
| | - Wen Zhong
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics & University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China
| | - Qiang Hao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics & University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China
| | - Dongwan Cheng
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics & University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China
| | - Xihao Hu
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Junjie Hou
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics & University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China
| | - Pingyong Xu
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Yuanchao Xue
- Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Yifa Zhou
- Jilin Province Key Laboratory on Chemistry and Biology of Changbai Mountain Natural Drugs, School of Life Sciences, Northeast Normal University, Changchun 130024, China
| | - Tao Xu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics & University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100101, China
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14
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Desai T, Koulajian K, Ivovic A, Breen DM, Luu L, Tsiani EL, Wheeler MB, Giacca A. Pharmacologic or genetic activation of SIRT1 attenuates the fat-induced decrease in beta-cell function in vivo. Nutr Diabetes 2019; 9:11. [PMID: 30890694 DOI: 10.1038/s41387-019-0075-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 12/14/2018] [Accepted: 01/31/2019] [Indexed: 12/11/2022] Open
Abstract
Background There is evidence that sirtuin 1 (SIRT1), a key regulator of nutrient metabolism, increases β-cell secretory function. Excess circulating fat, as seen in obesity, has been shown to decrease β-cell function, an effect that may involve decreased SIRT1 activity. Consequently, SIRT1 activation may increase β-cell function in conditions of elevated plasma-free fatty acid levels. Here we attempted to attenuate the lipid-induced decrease in β-cell function in vivo using pharmacological and genetic models of SIRT1 activation. Methods Our pharmacologic model involved 48 h intravenous infusion of Wistar rats with either saline or oleate with or without the SIRT1 activator resveratrol. Additionally, we used β-cell-specific SIRT1 overexpressing (BESTO) mice and wild-type littermates infused for 48 h intravenously with either saline or oleate. In both models, the infusion period was followed by assessment of β-cell function using the hyperglycemic clamp method. Results Lipid infusion resulted in a significant decrease in β-cell function as expected in both rats (p < 0.05) and mice (p < 0.001). Both models of SIRT1 activation, which did not alter β-cell function in the absence of fat, resulted in partial protection from the fat-induced decrease in β-cell function (NS vs. control). Conclusion These results suggest that SIRT1 is a therapeutic target in decreased β-cell function specifically induced by fat.
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15
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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16
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Wang Y, Liu J, Liu Z, Chen J, Hu X, Hu Y, Yuan Y, Wu G, Dai Z, Xu Y. Sall2 knockdown exacerbates palmitic acid induced dysfunction and apoptosis of pancreatic NIT-1 beta cells. Biomed Pharmacother 2018; 104:375-382. [PMID: 29783189 DOI: 10.1016/j.biopha.2018.05.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 04/25/2018] [Accepted: 05/07/2018] [Indexed: 12/12/2022] Open
Abstract
Spalt-like (Sall) proteins are a class of transcription factors. The role of Sall2 in beta cells remain poorly understood. Here, we aimed to explore whether Sall2 involved in lipotoxicity-mediated dysfunction and apoptosis in pancreatic NIT-1 beta cells. Our results showed that high concentrations of palmitic acid (PA) led to impaired cell viability and decreased Sall2 expression in NIT-1 cells. Knocking down of Sall2 in NIT-1 cells resulted in increased sensitivity to lipotoxicity and caused higher rates of cell apoptosis following PA treatment. Additionally, Sall2 Knockdown impaired insulin synthesis and secretion in response to glucose. Further research indicated Sall2 knockdown attenuate antioxidant capacity and decreased expression level of Peroxiredoxin 2 in NIT-1 cells. These finding implicate that Sall2 may play a significant role in NIT-1 cell function and cell apoptosis under lipotoxic conditions. Therefore, the study of Sall2 in NIT-1 cells provided a new perspective for molecular mechanism of lipotoxicity mediating dysfunction and apoptosis of beta cells.
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Affiliation(s)
- Ye Wang
- Department of Endocrinology, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, 430071, China
| | - Jie Liu
- Department of Endocrinology, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, 430071, China
| | - Zheng Liu
- Department of Endocrinology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu, 215006,China
| | - Jing Chen
- Department of Integrated Wards, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, 430071, China
| | - Xuemei Hu
- Department of Endocrinology, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, 430071, China
| | - Yimeng Hu
- Department of Endocrinology, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, 430071, China
| | - Yin Yuan
- Department of Endocrinology, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, 430071, China
| | - Guijun Wu
- Department of Endocrinology, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, 430071, China
| | - Zhe Dai
- Department of Endocrinology, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, 430071, China
| | - Yancheng Xu
- Department of Endocrinology, Zhongnan Hospital of Wuhan University, Wuhan, Hubei, 430071, China.
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Ivovic A, Oprescu AI, Koulajian K, Mori Y, Eversley JA, Zhang L, Nino-Fong R, Lewis GF, Donath MY, Karin M, Wheeler MB, Ehses J, Volchuk A, Chan CB, Giacca A. IKKβ inhibition prevents fat-induced beta cell dysfunction in vitro and in vivo in rodents. Diabetologia 2017; 60:2021-2032. [PMID: 28725915 DOI: 10.1007/s00125-017-4345-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 05/16/2017] [Indexed: 02/07/2023]
Abstract
AIMS/HYPOTHESIS We have previously shown that oxidative stress plays a causal role in beta cell dysfunction induced by fat. Here, we address whether the proinflammatory kinase inhibitor of (nuclear factor) κB kinase β (IKKβ), which is activated by oxidative stress, is also implicated. METHODS Fat (oleate or olive oil) was infused intravenously in Wistar rats for 48 h with or without the IKKβ inhibitor salicylate. Thereafter, beta cell function was evaluated in vivo using hyperglycaemic clamps or ex vivo in islets isolated from fat-treated rats. We also exposed rat islets to oleate in culture, with or without salicylate and 4(2'-aminoethyl)amino-1,8-dimethylimidazo(1,2-a)quinoxaline; BMS-345541 (BMS, another inhibitor of IKKβ) and evaluated beta cell function in vitro. Furthermore, oleate was infused in mice treated with BMS and in beta cell-specific Ikkb-null mice. RESULTS 48 h infusion of fat impaired beta-cell function in vivo, assessed using the disposition index (DI), in rats (saline: 1.41 ± 0.13; oleate: 0.95 ± 0.11; olive oil [OLO]: 0.87 ± 0.15; p < 0.01 for both fats vs saline) and in mice (saline: 2.51 ± 0.39; oleate: 1.20 ± 0.19; p < 0.01 vs saline) and ex vivo (i.e., insulin secretion, units are pmol insulin islet-1 h-1) in rat islets (saline: 1.51 ± 0.13; oleate: 1.03 ± 0.10; OLO: 0.91 ± 0.13; p < 0.001 for both fats vs saline) and the dysfunction was prevented by co-infusion of salicylate in rats (oleate + salicylate: 1.30 ± 0.09; OLO + salicylate: 1.33 ± 0.23) or BMS in mice (oleate + BMS: 2.25 ± 0.42) in vivo and by salicylate in rat islets ex vivo (oleate + salicylate: 1.74 ± 0.31; OLO + salicylate: 1.54 ± 0.29). In cultured islets, 48 h exposure to oleate impaired beta-cell function ([in pmol insulin islet-1 h-1] control: 0.66 ± 0.12; oleate: 0.23 ± 0.03; p < 0.01 vs saline), an effect prevented by both inhibitors (oleate + salicylate: 0.98 ± 0.08; oleate + BMS: 0.50 ± 0.02). Genetic inhibition of IKKβ also prevented fat-induced beta-cell dysfunction ex vivo ([in pmol insulin islet-1 h-1] control saline: 0.16 ± 0.02; control oleate: 0.10 ± 0.02; knockout oleate: 0.17 ± 0.04; p < 0.05 control saline vs. control oleate) and in vivo (DI: control saline: 3.86 ± 0.40; control oleate: 1.95 ± 0.29; knockout oleate: 2.96 ± 0.24; p < 0.01 control saline vs control oleate). CONCLUSIONS/INTERPRETATION Our results demonstrate a causal role for IKKβ in fat-induced beta cell dysfunction in vitro, ex vivo and in vivo.
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Affiliation(s)
- Aleksandar Ivovic
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada, M5S 1A8
| | - Andrei I Oprescu
- Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Khajag Koulajian
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada, M5S 1A8
| | - Yusaku Mori
- Division of Diabetes, Metabolism, and Endocrinology, Showa University School of Medicine, Shinagawa, Tokyo, Japan
| | - Judith A Eversley
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada, M5S 1A8
| | - Liling Zhang
- Division of Cellular and Molecular Biology, Toronto General Research Institute, University Health Network, Toronto, ON, Canada
| | - Rodolfo Nino-Fong
- Department of Biomedical Sciences, Ross University School of Veterinary Medicine, Basseterre, St Kitts and Nevis
| | - Gary F Lewis
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada, M5S 1A8
- Department of Medicine, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
- Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, Canada
| | - Marc Y Donath
- Department of Endocrinology, Diabetes, and Metabolism, University Hospital Basel, Basel, Switzerland
| | - Michael Karin
- Department of Pharmacology, University of California, San Diego, School of Medicine, La Jolla, CA, USA
| | - Michael B Wheeler
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada, M5S 1A8
| | - Jan Ehses
- Department of Surgery, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
- Child and Family Research Institute, Vancouver, BC, Canada
| | - Allen Volchuk
- Keenan Research Centre for Biomedical Science, St Michael's Hospital, Toronto, ON, Canada
| | - Catherine B Chan
- Department of Agriculture, Food and Nutritional Sciences, Faculty of Agricultural, Life and Environmental Sciences, University of Alberta, Edmonton, AB, Canada
- Department of Physiology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Adria Giacca
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada, M5S 1A8.
- Institute of Medical Science, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.
- Department of Medicine, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.
- Banting and Best Diabetes Centre, University of Toronto, Toronto, ON, Canada.
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Seghieri M, Tricò D, Natali A. The impact of triglycerides on glucose tolerance: Lipotoxicity revisited. Diabetes Metab 2017; 43:314-322. [PMID: 28693962 DOI: 10.1016/j.diabet.2017.04.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 04/19/2017] [Accepted: 04/27/2017] [Indexed: 12/22/2022]
Abstract
Elevated plasma triglycerides (TGs) are early key features of conditions associated with a dysregulation in glucose metabolism and may predict the development of type 2 diabetes (T2D) over time. Although the acute ingestion of lipid, either mixed with or shortly before the meal, is neutral or slightly beneficial on glucose tolerance, a short-term increase in plasma TGs induced by either an i.v. lipid infusion or a high-fat diet produces a deterioration of glucose control. Accordingly, chronic lowering of plasma TGs by fibrates improves glucose homeostasis and may also prevent T2D. The chronic effects of the elevation of dietary lipid intake are less clear, particularly in humans, being the quality of fat probably more important than total fat intake. Although on the bases of the available experimental and clinical evidence it cannot be easily disentangled, with respect to elevated non-esterified fatty acids (NEFA) the relative contribution of elevated TGs to glucose homeostasis disregulation seems to be greater and also more plausible. In conclusion, although the association between elevated plasma TGs and impaired glucose tolerance is commonly considered not causative or merely a consequence of NEFA-mediated lipotoxicity, the available data suggest that TGs per se may directly contribute to disorders of glucose metabolism.
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Affiliation(s)
- M Seghieri
- Department of clinical and experimental medicine, laboratory of metabolism, nutrition and atherosclerosis, university of Pisa, Pisa, Italy
| | - D Tricò
- Department of clinical and experimental medicine, laboratory of metabolism, nutrition and atherosclerosis, university of Pisa, Pisa, Italy
| | - A Natali
- Department of clinical and experimental medicine, laboratory of metabolism, nutrition and atherosclerosis, university of Pisa, Pisa, Italy.
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Rehman K, Akash MSH. Mechanism of Generation of Oxidative Stress and Pathophysiology of Type 2 Diabetes Mellitus: How Are They Interlinked? J Cell Biochem 2017; 118:3577-3585. [PMID: 28460155 DOI: 10.1002/jcb.26097] [Citation(s) in RCA: 287] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 04/26/2017] [Indexed: 12/14/2022]
Abstract
Oxidative stress has been considered as a major hallmark for the pathogenesis and development of type 2 diabetes mellitus (T2DM), but still it is debatable whether it is a mere aggregation of inflammatory-induced responses or clinical entity that underlies with various pathophysiological factors. In this regard, the latest studies have shown the increasing trends for the involvement of reactive oxygen species (ROS) and oxidative stress in the pathogenesis and development of T2DM. ROS are highly reactive species and almost all cellular components are chemically changed due to the influence of ROS that ultimately results in the production of lipid peroxidation. Lipid peroxidation is a major causative factor for the development of oxidative stress that leads to overt T2DM and its associated micro- and macro-vascular complications. In this article, we have briefly described the role of various causative factors, transcriptional and metabolic pathways which are responsible to increase the production of oxidative stress, a most pivotal factor for the pathogenesis and development of T2DM. Therefore, we conclude that measurement of oxidative stress biomarkers may be one of the optional tool for the diagnosis and prediction of T2DM. Moreover, the key findings described in this article also provides a new conceptual framework for forthcoming investigations on the role of oxidative stress in pathogenesis of T2DM and drug discovery. J. Cell. Biochem. 118: 3577-3585, 2017. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Kanwal Rehman
- Institute of Pharmacy, Physiology and Pharmacology, University of Agriculture, Faisalabad, Pakistan
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20
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Natali A, Baldi S, Bonnet F, Petrie J, Trifirò S, Tricò D, Mari A. Plasma HDL-cholesterol and triglycerides, but not LDL-cholesterol, are associated with insulin secretion in non-diabetic subjects. Metabolism 2017; 69:33-42. [PMID: 28285650 DOI: 10.1016/j.metabol.2017.01.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 12/15/2016] [Accepted: 01/03/2017] [Indexed: 01/01/2023]
Abstract
OBJECTIVE Experimental data support the notion that lipoproteins might directly affect beta cell function, however clinical data are sparse and inconsistent. We aimed at verifying whether, independently of major confounders, serum lipids are associated with alterations in insulin secretion or clearance non-diabetic subjects. METHODS Cross sectional and observational prospective (3.5yrs), multicentre study in which 1016 non-diabetic volunteers aged 30-60yrs. and with a wide range of BMI (20.0-39.9kg/m2) were recruited in a setting of University hospital ambulatory care (RISC study). MAIN OUTCOME MEASURES baseline fasting lipids, fasting and OGTT-induced insulin secretion and clearance (measured by glucose and C-peptide modeling), peripheral insulin sensitivity (by the euglycemic clamp). Lipids and OGTT were repeated in 980 subjects after 3.5years. RESULTS LDL-cholesterol did not show independent associations with fasting or stimulated insulin secretion or clearance. After accounting for potential confounders, HDL-cholesterol displayed negative and triglycerides positive independent associations with fasting and OGTT insulin secretion; neither with insulin clearance. Low HDL-cholesterol and high triglycerides were associated with an increase in glucose-dependent and a decrease in non-glucose-dependent insulin secretion. Over 3.5years both an HDL-cholesterol decline and a triglycerides rise were associated with an increase in fasting insulin secretion independent of changes in body weight or plasma glucose. CONCLUSIONS LDL-cholesterol does not seem to influence any major determinant of insulin bioavailability while low HDL-cholesterol and high triglycerides might contribute to sustain the abnormalities in insulin secretion that characterize the pre-diabetic state.
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Affiliation(s)
- Andrea Natali
- Department of Clinical and Experimental Medicine, University of Pisa, Italy.
| | - Simona Baldi
- Department of Clinical and Experimental Medicine, University of Pisa, Italy
| | - Fabrice Bonnet
- Service Endocrinologie-Diabétologie, Centre Hospitalo-Universitaire (CHU), University Rennes 1, Rennes, France
| | - John Petrie
- Institute of Cardiovascular and Medical Sciences BHF Glasgow Cardiovascular Research Centre, University of Glasgow, Glasgow, UK
| | - Silvia Trifirò
- Department of Clinical and Experimental Medicine, University of Pisa, Italy
| | - Domenico Tricò
- Department of Clinical and Experimental Medicine, University of Pisa, Italy
| | - Andrea Mari
- CNR Institute of Neuroscience, Padova, Italy
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21
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Zhang M, Wang B, Liu Y, Sun X, Luo X, Wang C, Li L, Zhang L, Ren Y, Zhao Y, Zhou J, Han C, Zhao J, Hu D. Cumulative increased risk of incident type 2 diabetes mellitus with increasing triglyceride glucose index in normal-weight people: The Rural Chinese Cohort Study. Cardiovasc Diabetol 2017; 16:30. [PMID: 28249577 DOI: 10.1186/s12933-017-0514-x] [Citation(s) in RCA: 146] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2016] [Accepted: 02/22/2017] [Indexed: 12/15/2022] Open
Abstract
Background Risk of type 2 diabetes mellitus (T2DM) is increased in metabolically obese but normal-weight people. However, we have limited knowledge of how to prevent T2DM in normal-weight people. We aimed to evaluate the association between triglyceride glucose (TyG) index and incident T2DM among normal-weight people in rural China. Methods We included data from 5706 people with normal body mass index (BMI) (18.5–23.9 kg/m2) without baseline T2DM in a rural Chinese cohort followed for a median of 6.0 years. A Cox proportional-hazard model was used to assess the risk of incident T2DM by quartiles of TyG index and difference in TyG index between follow-up and baseline (TyG-D), estimating hazard ratios (HRs) and 95% confidence intervals (CIs). A generalized additive plot was used to show the nonparametric smoothed exposure–response association between risk of T2DM and TyG index as a continuous variable. TyG was calculated as ln [fasting triglyceride level (mg/dl) × fasting plasma glucose level (mg/dl)/2]. Results Risk of incident T2DM was increased with quartiles 2, 3 and 4 versus quartile 1 of TyG index (adjusted HR [aHR] 2.48 [95% CI 1.20–5.11], 3.77 [1.83–7.79], and 5.30 [2.21–12.71], Ptrend < 0.001 across quartiles of TyG index). Risk of incident T2DM was increased with quartile 4 versus quartile 1 of TyG-D (aHR 3.91 [2.22–6.87]). The results were consistent when analyses were restricted to participants without baseline metabolic syndrome and impaired fasting glucose level. The generalized additive plot showed cumulative increased risk of T2DM with increasing TyG index. Conclusions Risk of incident T2DM is increased with increasing TyG index among rural Chinese people, so the index might be an important indicator for identifying people at high risk of T2DM.
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Shimo N, Matsuoka TA, Miyatsuka T, Takebe S, Tochino Y, Takahara M, Kaneto H, Shimomura I. Short-term selective alleviation of glucotoxicity and lipotoxicity ameliorates the suppressed expression of key β-cell factors under diabetic conditions. Biochem Biophys Res Commun 2015; 467:948-54. [DOI: 10.1016/j.bbrc.2015.10.038] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 10/07/2015] [Indexed: 01/14/2023]
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23
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Rebelos E, Seghieri M, Natali A, Balkau B, Golay A, Piatti PM, Lalic NM, Laakso M, Mari A, Ferrannini E. Influence of endogenous NEFA on beta cell function in humans. Diabetologia 2015; 58:2344-51. [PMID: 26160433 DOI: 10.1007/s00125-015-3685-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 06/15/2015] [Indexed: 12/20/2022]
Abstract
AIMS/HYPOTHESIS It is a commonly held view that chronically elevated NEFA levels adversely affect insulin secretion and insulin action (lipotoxicity). However, the effect of NEFA on beta cell function has only been explored using acute NEFA elevations. Our aim was to analyse the relationship between endogenous NEFA levels and beta cell function. METHODS In 1,267 individuals followed-up for 3 years, we measured insulin sensitivity (by clamp) and beta cell function (by C-peptide modelling during OGTT and as the acute insulin response [AIR] to IVGTT). RESULTS At baseline, both fasting and insulin-suppressed NEFA levels were higher across glucose tolerance groups, while insulin sensitivity was lower, insulin output was higher, and beta cell glucose sensitivity and AIR were lower (all p < 0.0001). In multiple logistic analyses adjusting for age, BMI, WHR and glucose tolerance, both fasting and insulin-suppressed NEFA levels were inversely related to insulin sensitivity, as expected (both p < 0.0001). Furthermore, after adjusting for insulin sensitivity, insulin-suppressed NEFA were positively associated with total insulin output (p = 0.0042). In contrast, neither fasting nor insulin-suppressed NEFA were related to beta cell glucose sensitivity or AIR. At follow-up, worsening of glucose tolerance (n = 126) was predicted by lower insulin and beta cell glucose sensitivity. In this model, baseline NEFA were not significant predictors of progression. CONCLUSIONS/INTERPRETATION In the non-diabetic state and in subjects with impaired glucose tolerance, circulating endogenous NEFA are not independently associated measures of beta cell function, and do not predict deterioration of glucose tolerance. Thus, in the Relationship Between Insulin Sensitivity and Cardiovascular Disease (RISC) cohort there is no evidence for beta cell lipotoxicity of endogenous total NEFA concentrations.
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Affiliation(s)
- Eleni Rebelos
- Department of Clinical & Experimental Medicine, University of Pisa, Via Roma, 67, 56126, Pisa, Italy
| | - Marta Seghieri
- Department of Clinical & Experimental Medicine, University of Pisa, Via Roma, 67, 56126, Pisa, Italy
| | - Andrea Natali
- Department of Clinical & Experimental Medicine, University of Pisa, Via Roma, 67, 56126, Pisa, Italy
| | | | - Alain Golay
- Division of Therapeutical Teaching for Chronic Diseases, University Hospital, Geneva, Switzerland
| | - Pier Marco Piatti
- Cardio-Metabolism and Clinical Trials Unit, Department of Internal Medicine, IRCCS Ospedale San Raffaele, Milan, Italy
| | - Nebojsa M Lalic
- Clinic for Endocrinology, Diabetes and Metabolic Diseases, CCS, Faculty of Medicine, University of Belgrade, Belgrade, Serbia
| | - Markku Laakso
- Department of Medicine, University of Eastern Finland and Kuopio University Hospital, Kuopio, Finland
| | - Andrea Mari
- CNR Institute of Neuroscience, Padova, Italy
| | - Ele Ferrannini
- Department of Clinical & Experimental Medicine, University of Pisa, Via Roma, 67, 56126, Pisa, Italy.
- CNR Institute of Clinical Physiology, Pisa, Italy.
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Kanekura K, Ou J, Hara T, Zhu LJ, Urano F. Research resource: Monitoring endoplasmic reticulum membrane integrity in β-cells at the single-cell level. Mol Endocrinol 2015; 29:473-80. [PMID: 25584413 DOI: 10.1210/me.2014-1260] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Endoplasmic reticulum (ER) membrane integrity is an emerging target for human chronic diseases associated with ER stress. Despite the underlying importance of compromised ER membrane integrity in disease states, the entire process leading to ER membrane permeabilization and cell death is still not clear due to technical limitations. Here we describe a novel method for monitoring ER membrane integrity at the single-cell level in real time. Using a β-cell line expressing ER-targeted redox sensitive green fluorescent protein, we could identify a β-cell population undergoing ER membrane permeabilization induced by palmitate and could monitor cell fate and ER stress of these cells at the single-cell level. Our method could be used to develop a novel therapeutic modality targeting the ER membrane for ER-associated disorders, including β-cell death in diabetes, neurodegeneration, and Wolfram syndrome.
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Affiliation(s)
- Kohsuke Kanekura
- Department of Medicine (K.K., T.H., F.U.), Division of Endocrinology, Metabolism, and Lipid Research, and Department of Pathology and Immunology (F.U.), Washington University School of Medicine, St Louis, Missouri 63110; and Programs in Gene Function and Expression, Molecular Medicine, and Bioinformatics and Integrative Biology (J.O., L.J.Z.), University of Massachusetts Medical School, Worcester, Massachusetts 01655
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25
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Abstract
Adipose tissue is an organ with active endocrine function involved in the regulation of energy balance and glucose homeostasis via multiple metabolic signaling pathways targeting the brain, liver, skeletal muscle, pancreas, and other organs. There is increasing evidence demonstrating that the female sex hormone, estrogen, regulates adipose development and improves systemic glucose homeostasis in both males and females. The underlying mechanism linking estrogenic regulation in adipose tissue and systemic glucose metabolism has not been fully elucidated, but is thought to include interactions of estrogen receptor signaling events involving lipolytic and/or lipogenic enzyme activity, free fatty acid metabolism, and adipocytokine production. Thus, understanding the effects of estrogen replacement on adipose tissue biology and metabolism is important in determining the risk of developing obesity-related metabolic disorders in patients undergoing treatment for sex hormone deficiency. In this report, we review literature regarding the role of estrogens and their corresponding receptors in the control of adipose metabolism and glucose homeostasis in both rodents and humans. We also discuss the effects of selective estrogen receptor modulators on glucose metabolism.
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Affiliation(s)
- Jun Ho Kim
- Department of Food and Biotechnology, Korea University, Sejong 339-700, Republic of Korea
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26
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Jenkins NT, Padilla J, Martin JS, Crissey JM, Thyfault JP, Rector RS, Laughlin MH. Differential vasomotor effects of insulin on gastrocnemius and soleus feed arteries in the OLETF rat model: role of endothelin-1. Exp Physiol 2013; 99:262-71. [PMID: 23995100 DOI: 10.1113/expphysiol.2013.074047] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The vascular actions of insulin are complex, because it can stimulate both nitric oxide-mediated dilatation and endothelin (ET)-1-mediated constriction. We examined vasoreactivity to insulin in isolated feed arteries of the gastrocnemius (GFA) and soleus muscles (SFA) of 32-week-old Long-Evans Tokushima Otsuka (LETO) and Otsuka Long-Evans Tokushima fatty (OLETF) rats, a hyperphagic rodent model of obesity and insulin resistance. The insulin-induced vasoreactivity of SFA and GFA was similar in LETO (healthy) and OLETF (obese/insulin-resistant) rats. However, examination of between-vessel effects revealed a number of novel insights into the heterogeneous vascular effects of insulin. Soleus feed arteries dilated more than GFA in LETO at 100 and 1000 μIU ml(-1) insulin (23 versus 6 and 28 versus 0%, respectively; P < 0.05 for between-vessel differences). Likewise, in OLETF rats there was significantly greater dilatation in SFA than GFA at 10, 100 and 1000 μIU ml(-1) insulin (28 versus 3, 30 versus 0 and 34 versus 0%, respectively; all P < 0.05). In the presence of 3 μm tezosentan, a non-specific endothelin-1 receptor blocker, insulin-induced dilatation of the GFA was enhanced such that differences between vessels were largely abolished in both groups. Furthermore, acetylecholine-induced dilatation was significantly greater in SFA than GFA within each group, whereas sodium nitroprusside-induced dilatory responses were greater in the GFA compared with the SFA. Overall, our findings indicate that the insulin/endothelin-1 vasoconstrictor pathway is more active in GFA than in SFA, independent of obesity in the OLETF rat model.
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Affiliation(s)
- Nathan T Jenkins
- N. T. Jenkins: 115M Ramsey Center, Department of Kinesiology, University of Georgia, 330 River Road, Athens, GA 30602-6554, USA.
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27
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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28
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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29
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Zhao Y, Wang L, Qiu J, Zha D, Sun Q, Chen C. Linoleic acid stimulates [Ca2+]i increase in rat pancreatic beta-cells through both membrane receptor- and intracellular metabolite-mediated pathways. PLoS One 2013; 8:e60255. [PMID: 23565210 PMCID: PMC3614997 DOI: 10.1371/journal.pone.0060255] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Accepted: 02/24/2013] [Indexed: 01/08/2023] Open
Abstract
The role of the free fatty acid (FFA) receptor and the intracellular metabolites of linoleic acid (LA) in LA-stimulated increase in cytosolic free calcium concentration ([Ca2+]i) was investigated. [Ca2+]i was measured using Fura-2 as indicator in rat pancreatic β-cells in primary culture. LA (20 µM for 2 min) stimulated a transient peak increase followed by a minor plateau increase in [Ca2+]i. Elongation of LA stimulation up to 10 min induced a strong and long-lasting elevation in [Ca2+]i. Activation of FFA receptors by the non-metabolic agonist GW9508 (40 µM for 10 min) resulted in an increase in [Ca2+]i similar to that of 2-min LA treatment. Inhibition of acyl-CoA synthetases by Triacsin C suppressed the strong and long-lasting increase in [Ca2+]i. The increase in [Ca2+]i induced by 2 min LA or GW9508 were fully eliminated by exhaustion of endoplasmic reticulum (ER) Ca2+ stores or by inhibition of phospholipase C (PLC). Removal of extracellular Ca2+ did not influence the transient peak increase in [Ca2+]i stimulated by 2 min LA or GW9508. The strong and long-lasting increase in [Ca2+]i induced by 10 min LA was only partially suppressed by extracellular Ca2+ removal or thapsigargin pretreatment, whereas remaining elevation in [Ca2+]i was eliminated after exhaustion of mitochondrial Ca2+ using triphenyltin. In conclusion, LA stimulates Ca2+ release from ER through activation of the FFA receptor coupled to PLC and mobilizes mitochondrial Ca2+ by intracellular metabolites in β-cells.
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Affiliation(s)
- Yufeng Zhao
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia
- Department of Otolaryngology, Xijing Hospital, Fourth Military Medical University, Xi’an, China
- * E-mail: (CC); (YZ)
| | - Li Wang
- The Second Affiliated Hospital of Medical School, Xi’an Jiao Tong University, Xi’an, China
| | - Jianhua Qiu
- Department of Otolaryngology, Xijing Hospital, Fourth Military Medical University, Xi’an, China
| | - Dingjun Zha
- Department of Otolaryngology, Xijing Hospital, Fourth Military Medical University, Xi’an, China
| | - Qiang Sun
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Chen Chen
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia
- * E-mail: (CC); (YZ)
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Pereira S, Yu WQ, Frigolet ME, Beaudry JL, Shpilberg Y, Park E, Dirlea C, Nyomba BLG, Riddell MC, Fantus IG, Giacca A. Duration of rise in free fatty acids determines salicylate's effect on hepatic insulin sensitivity. J Endocrinol 2013; 217:31-43. [PMID: 23328071 PMCID: PMC3601809 DOI: 10.1530/joe-12-0214] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
We have shown in rats that sodium salicylate (SS), which inhibits IkBa kinase B (IKKB), prevents hepatic and peripheral insulin resistance caused by short-term (7 h) i.v. administration of Intralipid and heparin (IH). We wished to further determine whether this beneficial effect of SS persisted after prolonged (48 h) IH infusion, which better mimics the chronic free fatty acid (FFA) elevation of obesity. Hence, we performed hyperinsulinemic euglycemic clamps with tritiated glucose methodology to determine hepatic and peripheral insulin sensitivity in rats infused with saline, IH, IH and SS, or SS alone. SS prevented peripheral insulin resistance (P<0.05) caused by prolonged plasma FFA elevation; however, it did not prevent hepatic insulin resistance. In skeletal muscle, protein levels of phospho-IkBa were augmented by prolonged IH administration and this was prevented by SS, suggesting that IH activates while SS prevents the activation of IKKB. Markers of IKKB activation, namely protein levels of phospho-IkBa and IkBa, indicated that IKKB is not activated in the liver after prolonged FFA elevation. Phosphorylation of serine 307 at insulin receptor substrate (IRS)-1, which is a marker of proximal insulin resistance, was not altered by IH administration in the liver, suggesting that this is not a site of hepatic insulin resistance in the prolonged lipid infusion model. Our results suggest that the role of IKKB in fat-induced insulin resistance is time and tissue dependent and that hepatic insulin resistance induced by prolonged lipid elevation is not due to an IRS-1 serine 307 kinase.
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MESH Headings
- Animals
- Anti-Inflammatory Agents, Non-Steroidal/administration & dosage
- Anti-Inflammatory Agents, Non-Steroidal/therapeutic use
- Disease Models, Animal
- Emulsions
- Fatty Acids, Nonesterified/blood
- Female
- Heparin
- I-kappa B Proteins/antagonists & inhibitors
- I-kappa B Proteins/metabolism
- Infusions, Intravenous
- Insulin Resistance
- Kinetics
- Liver/drug effects
- Liver/metabolism
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/immunology
- Muscle, Skeletal/metabolism
- NF-KappaB Inhibitor alpha
- Obesity/blood
- Obesity/drug therapy
- Obesity/immunology
- Obesity/metabolism
- Phospholipids
- Phosphorylation/drug effects
- Protein Processing, Post-Translational/drug effects
- Random Allocation
- Rats
- Rats, Wistar
- Sodium Salicylate/administration & dosage
- Sodium Salicylate/therapeutic use
- Soybean Oil
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Affiliation(s)
- Sandra Pereira
- Department of Physiology, University of TorontoMedical Sciences Building, 1 King's College Circle, Toronto, Ontario, M5S 1A8Canada
| | - Wen Qin Yu
- Department of Physiology, University of TorontoMedical Sciences Building, 1 King's College Circle, Toronto, Ontario, M5S 1A8Canada
| | - María E Frigolet
- Department of Medicine, Mount Sinai HospitalToronto, OntarioCanada
- Toronto General Research Institute and Banting and Best Diabetes Centre, University Health NetworkToronto, OntarioCanada
| | - Jacqueline L Beaudry
- Muscle Health Research Center and Physical Activity and Chronic Disease Unit, Faculty of Health, School of Kinesiology and Health Science, York UniversityToronto, OntarioCanada
| | - Yaniv Shpilberg
- Muscle Health Research Center and Physical Activity and Chronic Disease Unit, Faculty of Health, School of Kinesiology and Health Science, York UniversityToronto, OntarioCanada
| | - Edward Park
- Department of Physiology, University of TorontoMedical Sciences Building, 1 King's College Circle, Toronto, Ontario, M5S 1A8Canada
| | - Cristina Dirlea
- Department of Physiology, University of TorontoMedical Sciences Building, 1 King's College Circle, Toronto, Ontario, M5S 1A8Canada
| | - B L Grégoire Nyomba
- Department of Internal Medicine, University of ManitobaWinnipeg, ManitobaCanada
| | - Michael C Riddell
- Muscle Health Research Center and Physical Activity and Chronic Disease Unit, Faculty of Health, School of Kinesiology and Health Science, York UniversityToronto, OntarioCanada
| | - I George Fantus
- Department of Physiology, University of TorontoMedical Sciences Building, 1 King's College Circle, Toronto, Ontario, M5S 1A8Canada
- Department of Medicine, Mount Sinai HospitalToronto, OntarioCanada
- Toronto General Research Institute and Banting and Best Diabetes Centre, University Health NetworkToronto, OntarioCanada
| | - Adria Giacca
- Department of Physiology, University of TorontoMedical Sciences Building, 1 King's College Circle, Toronto, Ontario, M5S 1A8Canada
- Correspondence should be addressed to A Giacca;
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32
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Cui W, Ma J, Wang X, Yang W, Zhang J, Ji Q. Free fatty acid induces endoplasmic reticulum stress and apoptosis of β-cells by Ca2+/calpain-2 pathways. PLoS One 2013; 8:e59921. [PMID: 23527285 PMCID: PMC3604010 DOI: 10.1371/journal.pone.0059921] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2012] [Accepted: 02/19/2013] [Indexed: 12/28/2022] Open
Abstract
Dysfunction of β-cells is a major characteristic in the pathogenesis of type 2 diabetes mellitus (T2DM). The combination of obesity and T2DM is associated with elevated plasma free fatty acids (FFAs). However, molecular mechanisms linking FFAs to β-cell dysfunction remain poorly understood. In the present study, we identified that the major endoplasmic reticulum stress (ERS) marker, Grp78 and ERS-induced apoptotic factor, CHOP, were time-dependently increased by exposure of β-TC3 cells to FFA. The expression of ATF6 and the phosphorylation levels of PERK and IRE1, which trigger ERS signaling, markedly increased after FFA treatments. FFA treatments increased cell apoptosis by inducing ERS in β-TC3 cells. We also found that FFA-induced ERS was mediated by the store-operated Ca2+ entry through promoting the association of STIM1 and Orai1. Moreover, calpain-2 was required for FFA-induced expression of CHOP and activation of caspase-12 and caspase-3, thus promoting cell apoptosis in β-TC3 cells. Together, these results reveal pivotal roles for Ca2+/calpain-2 pathways in modulating FFA-induced β-TC3 cell ERS and apoptosis.
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Affiliation(s)
- Wei Cui
- Department of Endocrinology and Metabolism, Xijing Hospital, Fourth Military Medical University, Xi’an, China
| | - Jie Ma
- Department of Neurosurgery, Tangdu Hospital, Forth Military Medical University, Xi’an, China
| | - Xingqin Wang
- Department of Neurosurgery, Tangdu Hospital, Forth Military Medical University, Xi’an, China
| | - Wenjuan Yang
- Department of Endocrinology and Metabolism, Xijing Hospital, Fourth Military Medical University, Xi’an, China
| | - Jing Zhang
- No. 371 Central Hospital of People’s Liberation Army, Xinxiang, China
| | - Qiuhe Ji
- Department of Endocrinology and Metabolism, Xijing Hospital, Fourth Military Medical University, Xi’an, China
- * E-mail:
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Salgin B, Ong KK, Thankamony A, Emmett P, Wareham NJ, Dunger DB. Higher fasting plasma free fatty acid levels are associated with lower insulin secretion in children and adults and a higher incidence of type 2 diabetes. J Clin Endocrinol Metab 2012; 97:3302-9. [PMID: 22740706 DOI: 10.1210/jc.2012-1428] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
CONTEXT There are limited data in humans on the association between fasting free fatty acid (FFA) levels and pancreatic β-cell function. OBJECTIVE Our objective was to examine this association in children and adults with normal glucose tolerance and to explore fasting FFA levels in relation to subsequent risk of impaired glucose tolerance (IGT) and type 2 diabetes (T2D). DESIGN We measured FFA, glucose, and insulin levels after an overnight fast and 30 min after an oral glucose load in 797 children aged 8 yr in the Avon Longitudinal Study of Parents and Children and 770 adults aged 44-71 yr in the Medical Research Council Ely Study. We calculated the homeostasis model assessment to estimate fasting insulin sensitivity, the insulinogenic index to estimate insulin secretion, and the disposition index to assess insulin secretion corrected for insulin sensitivity. RESULTS Higher fasting FFA levels were associated with lower insulin secretion in children (boys, P = 0.03; girls, P = 0.001) and adults (men, P = 0.03, women, P = 0.04). Associations with insulin sensitivity were more variable, but after adjustment for insulin sensitivity, higher fasting FFA levels remained associated with lower insulin secretion (disposition index). Compared with adults in the lowest tertile of fasting FFA levels, those in the middle and highest tertiles had a 3-fold higher incidence of IGT or T2D over the following 5-8 yr. CONCLUSIONS Higher fasting FFA levels were consistently associated with lower insulin secretion in children and adults with normal glucose tolerance. Furthermore, higher fasting FFA levels were prospectively associated with a greater risk of subsequent IGT and T2D.
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Affiliation(s)
- Burak Salgin
- University Department of Paediatrics, University of Cambridge, Cambridge CB2 0QQ, United Kingdom.
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35
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Leroy JLMR, Rizos D, Sturmey R, Bossaert P, Gutierrez-Adan A, Van Hoeck V, Valckx S, Bols PEJ. Intrafollicular conditions as a major link between maternal metabolism and oocyte quality: a focus on dairy cow fertility. Reprod Fertil Dev 2012; 24:1-12. [DOI: 10.1071/rd11901] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Reduced oocyte and embryo quality are recognised as major factors in the problem of disappointing fertility in high producing dairy cows. This review aims to shed more light on the importance of the intrafollicular environment in the subfertility problem in dairy cows. Metabolic disturbances associated with negative energy balance (NEB) early postpartum are associated with ovarian dysfunction. Changes in the growth pattern of the ovarian follicle during a period of NEB can indirectly affect oocyte quality. Furthermore, a maternal metabolic disorder (linked with NEB or nutritionally induced) may alter the endocrine and biochemical composition of the follicular fluid, the micro-environment of the growing and maturing female gamete. The maturing oocyte is very sensitive to any perturbation in its direct environment and in vitro maturation models revealed that some of these metabolic changes reduce the oocyte’s developmental competence. Also, embryo quality is significantly reduced due to maturation in adverse conditions. Well balanced and timed oocyte metabolism and gene expression are crucial to safeguard an optimal oocyte development. In that perspective, metabolome and transcriptome parameters of the oocyte may serve to predict reproductive success rates. Finally, there is growing evidence that adverse conditions for oocyte growth and maturation may also jeopardise the health and performance of the offspring.
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36
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Figueira TR, Ribeiro RA, Ignacio-Souza LM, Vercesi AE, Carneiro EM, Oliveira HCF. Enhanced insulin secretion and glucose tolerance in rats exhibiting low plasma free fatty acid levels and hypertriglyceridaemia due to congenital albumin deficiency. Exp Physiol 2011; 97:525-33. [PMID: 22198013 DOI: 10.1113/expphysiol.2011.062307] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Congenitally analbuminaemic individuals and rats (NARs) exhibit several metabolic abnormalities, including hypertriglyceridaemia and plasma free fatty acid deficiency. Our aim was to study glucose homeostasis and insulin secretion in NARs. Plasma concentrations of lipids, glucose and insulin and secretion of insulin from the pancreatic islets were measured in female NARs and control animals (Sprague-Dawley rats; SDRs). Glucose homeostasis tests were also performed. Plasma glucose levels were similar between NARs and SDRs, irrespective of feeding status. However, fed insulinaemia was ∼37% higher (P 0.05) in NARs than in SDRs. The NARs displayed a markedly increased glucose tolerance, i.e. the integrated glycaemic response was one-third that of the control animals. Enhanced glucose tolerance was associated with threefold higher insulinaemia at peak glycaemia after a glucose load than in the control animals. Similar peripheral insulin sensitivity was observed between groups. Isolated pancreatic islets from NARs secreted significantly more insulin than islets from SDRs in response to a wide range of glucose concentrations (2.8-33.3 mm). Despite having similar liver glycogen contents in the fully fed state, NARs had ∼40% (P 0.05) lower glycogen contents than SDRs after 6 h fasting. The injection of a gluconeogenic substrate, pyruvate, elicited a faster rise in glycaemia in NARs compared with SDRs. Overall, NARs displayed enhanced glucose tolerance, insulin secretion and gluconeogenic flux. The higher glucose tolerance in NARs compared with SDRs is attributed to enhanced islet responsiveness to secretagogues, while peripheral insulin sensitivity seems not to be involved in this alteration. We propose that the enhanced glucose metabolism is a chronic compensatory adaptation to decreased free fatty acid availability in NARs.
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Affiliation(s)
- Tiago R Figueira
- Departamento de Patologia Clínica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, SP, Brazil
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Peng G, Li L, Liu Y, Pu J, Zhang S, Yu J, Zhao J, Liu P. Oleate blocks palmitate-induced abnormal lipid distribution, endoplasmic reticulum expansion and stress, and insulin resistance in skeletal muscle. Endocrinology 2011; 152:2206-18. [PMID: 21505048 DOI: 10.1210/en.2010-1369] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Pathological elevation of plasma fatty acids reduces insulin sensitivity. Although several regulation pathways have been reported, the molecular mechanisms of insulin sensitivity remain elusive, especially in skeletal muscle where most glucose is consumed. This study focuses on how two major dietary fatty acids affect insulin signaling in skeletal muscle cells. Palmitic acid (PA) not only reduced insulin-stimulated phosphorylation of Akt but also induced endoplasmic reticulum (ER) expansion and ER stress. Relieving ER stress using 4-phenyl butyric acid blocked PA-mediated protein kinase R-like ER kinase phosphorylation and ER expansion and reversed the inhibitory effect of PA on insulin-stimulated Akt phosphorylation. Importantly, oleic acid (OA) could also recover PA-reduced Akt phosphorylation and abolish both PA-mediated ER expansion and ER stress. The competition between these two fatty acids was further verified in rat skeletal muscle using venous fatty acid infusion. (3)H-labeled PA was converted mainly to active lipids (phospholipids and diacylglycerol) in the absence of OA, but to triacylglycerol in the presence of OA. Subcellular triacylglycerol and adipocyte differentiation-related protein from PA-treated cells cofractionated with the ER in the absence of OA but switched to the low-density fraction in the presence of OA. Taken together, these data suggest that the PA-mediated lipid composition and localization may cause ER expansion and consequently cause ER stress and insulin resistance in skeletal muscle.
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Affiliation(s)
- Gong Peng
- National Laboratory of Biomacromolecules, Institute of Biophysics and Graduate University, Chinese Academy of Sciences, Beijing, 100101, China
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38
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Abstract
The phenomenon of lipid-induced pancreatic β-cell dysfunction ("lipotoxicity") has been very well documented in numerous in vitro experimental systems and has become widely accepted. In vivo demonstration of β-cell lipotoxicity, on the other hand, has not been consistently demonstrated, and there remains a lack of consensus regarding the in vivo effects of chronically elevated free fatty acids (FFA) on β-cell function. Much of the disagreement relates to how insulin secretion is quantified in vivo and in particular whether insulin secretion is assessed in relation to whole body insulin sensitivity, which is clearly reduced by elevated FFA. By correcting for changes in in vivo insulin sensitivity, we and others have shown that prolonged elevation of FFA impairs β-cell secretory function. Prediabetic animal models and humans with a positive family history of type 2 diabetes are more susceptible to this impairment, whereas those with severe impairment of β-cell function (such as individuals with type 2 diabetes) demonstrate no additional impairment of β-cell function when FFA are experimentally raised. Glucolipotoxicity (i.e., the combined β-cell toxicity of elevated glucose and FFA) has been amply demonstrated in vitro and in some animal studies but not in humans, perhaps because there are limitations in experimentally raising plasma glucose to sufficiently high levels for prolonged periods of time. We and others have shown that therapies directed toward diminishing oxidative stress and ER stress have the potential to reduce lipid-induced β-cell dysfunction in animals and humans. In conclusion, lipid-induced pancreatic β-cell dysfunction is likely to be one contributor to the complex array of genetic and metabolic insults that result in the relentless decline in pancreatic β-cell function in those destined to develop type 2 diabetes, and mechanisms involved in this lipotoxicity are promising therapeutic targets.
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Affiliation(s)
- Adria Giacca
- Dept. of Physiology, Univ. of Toronto, ON, Canada.
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39
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Yuan H, Zhang X, Huang X, Lu Y, Tang W, Man Y, Wang S, Xi J, Li J. NADPH oxidase 2-derived reactive oxygen species mediate FFAs-induced dysfunction and apoptosis of β-cells via JNK, p38 MAPK and p53 pathways. PLoS One 2010; 5:e15726. [PMID: 21209957 PMCID: PMC3012098 DOI: 10.1371/journal.pone.0015726] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Accepted: 11/20/2010] [Indexed: 01/08/2023] Open
Abstract
Dysfunction of β-cell is one of major characteristics in the pathogenesis of type 2 diabetes. The combination of obesity and type 2 diabetes, characterized as ‘diabesity’, is associated with elevated plasma free fatty acids (FFAs). Oxidative stress has been implicated in the pathogenesis of FFA-induced β-cell dysfunction. However, molecular mechanisms linking between reactive oxygen species (ROS) and FFA-induced β-cell dysfunction and apoptosis are less clear. In the present study, we test the hypothesis that NOX2-derived ROS may play a critical role in dysfunction and apoptosis of β-cells induced by FFA. Our results show that palmitate and oleate (0.5 mmol/L, 48 h) induced JNK activation and AKT inhibition which resulted in decreased phosphorylation of FOXO1 following nuclear localization and the nucleocytoplasmic translocation of PDX-1, leading to the reducing of insulin and ultimately dysfunction of pancreatic NIT-1 cells. We also found that palmitate and oleate stimulated apoptosis of NIT-1 cells through p38MAPK, p53 and NF-κB pathway. More interestingly, our data suggest that suppression of NOX2 may restore FFA-induced dysfunction and apoptosis of NIT-1 cells. Our findings provide a new insight of the NOX2 as a potential new therapeutic target for preservation of β-cell mass and function.
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Affiliation(s)
- Huiping Yuan
- Department of Biomedical Engineering, College of Engineering, Peking University, Beijing, China
- Peking University Fifth School of Clinical Medicine, Beijing Hospital, Beijing, China
| | - Xiaoyong Zhang
- Graduate School of Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
| | - Xiuqing Huang
- Peking University Fifth School of Clinical Medicine, Beijing Hospital, Beijing, China
| | - Yonggang Lu
- Graduate School of Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
| | - Weiqing Tang
- Peking University Fifth School of Clinical Medicine, Beijing Hospital, Beijing, China
| | - Yong Man
- Peking University Fifth School of Clinical Medicine, Beijing Hospital, Beijing, China
| | - Shu Wang
- Peking University Fifth School of Clinical Medicine, Beijing Hospital, Beijing, China
| | - Jianzhong Xi
- Department of Biomedical Engineering, College of Engineering, Peking University, Beijing, China
- * E-mail: (JL); (JX)
| | - Jian Li
- Peking University Fifth School of Clinical Medicine, Beijing Hospital, Beijing, China
- Graduate School of Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
- * E-mail: (JL); (JX)
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40
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Wu N, Lu Y, He B, Zhang Y, Lin J, Zhao S, Zhang W, Li Y, Han P. Taurine prevents free fatty acid-induced hepatic insulin resistance in association with inhibiting JNK1 activation and improving insulin signaling in vivo. Diabetes Res Clin Pract 2010; 90:288-96. [PMID: 20855122 DOI: 10.1016/j.diabres.2010.08.020] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2010] [Revised: 08/09/2010] [Accepted: 08/19/2010] [Indexed: 10/19/2022]
Abstract
We infused the 48 h intralipid plus heparin (IH) to normal rats to elevate plasma free fatty acids (FFAs). Co-infusion of taurine was designed for the purpose of studying the effects of taurine on insulin sensitivity, oxidative stress, c-Jun NH-terminal kinase (JNK)1 activity and insulin signaling in livers of prolonged IH-infused rats. Cannulated rats were infused for 48 h intravenously with either saline or IH, with or without taurine. Hyperinsulinemic-euglycemic clamps with [6-3H] glucose infusion were performed to assess hepatic insulin sensitivity. IH infusion increased plasma 8-isoprostaglandin and hepatic malondialdehyde (MDA). IH also increased JNK1 activity and insulin receptor substrate 1/2 (IRS-1/2) serine phosphorylation, reduced insulin-stimulated IRS-1/2 tyrosine phosphorylation and Akt serine 473 phosphorylation, and induced hepatic insulin resistance. Taurine co-infusion with IH prevented the rise in 8-isoprostaglandin and MDA, inhibited the activation of JNK1, and improved insulin signaling and insulin resistance in liver. The present study has demonstrated that taurine, as an antioxidant, prevented hepatic oxidative stress and ameliorated hepatic insulin resistance. And this effect may be associated with the inhibition of JNK1 activation and the improvement of insulin signaling. This study suggests the therapeutic value of taurine in protecting from hepatic insulin resistance caused by elevated FFAs.
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Affiliation(s)
- Na Wu
- Department of Endocrinology, Shengjing Hospital of China Medical University, Shenyang 110004, China
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41
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Abstract
This research perspective allows me to summarize some of my work completed over 50 years, and it is organized in seven sections. 1) The treatment of diabetes concentrates on the liver and/or the periphery. We quantified hormonal and metabolic interactions involved in physiology and the pathogenesis of diabetes by developing tracer methods to separate the effects of diabetes on both. We collaborated in the first tracer clinical studies on insulin resistance, hypertriglyceridemia, and the Cori cycle. 2) Diabetes reflects insulin deficiency and glucagon abundance. Extrapancreatic glucagon changed the prevailing dogma and permitted precise exploration of the roles of insulin and glucagon in physiology and diabetes. 3) We established the critical role of glucagon-insulin interaction and the control of glucose metabolism during moderate exercise and of catecholamines during strenuous exercise. Deficiencies of the release and effects of these hormones were quantified in diabetes. We also revealed how acute and chronic hyperglycemia affects the expression of GLUT2 gene and protein in diabetes. 4) We outlined molecular and physiological mechanisms whereby exercise training and repetitive neurogenic stress can prevent diabetes in ZDF rats. 5) We and others established that the indirect effect of insulin plays an important role in the regulation of glucose production in dogs. We confirmed this effect in humans and demonstrated that in type 2 diabetes it is mainly the indirect effect. 6) We indicated that the muscle and the liver protected against glucose changes. 7) We described molecular mechanisms responsible for increased HPA axis in diabetes and for the diminished responses of HPA axis, catecholamines, and glucagon to hypoglycemia. We proposed a new approach to decrease the threat of hypoglycemia.
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Affiliation(s)
- Mladen Vranic
- Dept. of Physiology, Univ. of Toronto, Toronto, ON. Canada M5S 1A8.
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42
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Fontés G, Zarrouki B, Hagman DK, Latour MG, Semache M, Roskens V, Moore PC, Prentki M, Rhodes CJ, Jetton TL, Poitout V. Glucolipotoxicity age-dependently impairs beta cell function in rats despite a marked increase in beta cell mass. Diabetologia 2010; 53:2369-79. [PMID: 20628728 PMCID: PMC2947580 DOI: 10.1007/s00125-010-1850-5] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2010] [Accepted: 06/18/2010] [Indexed: 01/25/2023]
Abstract
AIMS/HYPOTHESIS Prolonged exposure of pancreatic beta cells to excessive levels of glucose and fatty acids, referred to as glucolipotoxicity, is postulated to contribute to impaired glucose homeostasis in patients with type 2 diabetes. However, the relative contribution of defective beta cell function vs diminished beta cell mass under glucolipotoxic conditions in vivo remains a subject of debate. We therefore sought to determine whether glucolipotoxicity in rats is due to impaired beta cell function and/or reduced beta cell mass, and whether older animals are more susceptible to glucolipotoxic condition. METHODS Wistar rats (2 and 6 months old) received a 72 h infusion of glucose + intravenous fat emulsion or saline control. In vivo insulin secretion and sensitivity were assessed by hyperglycaemic clamps. Ex vivo insulin secretion, insulin biosynthesis and gene expression were measured in isolated islets. Beta cell mass and proliferation were examined by immunohistochemistry. RESULTS A 72 h infusion of glucose + intravenous fat emulsion in 2-month-old Wistar rats did not affect insulin sensitivity, insulin secretion or beta cell mass. In 6-month-old rats by contrast it led to insulin resistance and reduced insulin secretion in vivo, despite an increase in beta cell mass and proliferation. This was associated with: (1) diminished glucose-stimulated second-phase insulin secretion and proinsulin biosynthesis; (2) lower insulin content; and (3) reduced expression of beta cell genes in isolated islets. CONCLUSIONS/INTERPRETATION In this in vivo model, glucolipotoxicity is characterised by an age-dependent impairment of glucose-regulated beta cell function despite a marked increase in beta cell mass.
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Affiliation(s)
- G. Fontés
- Montreal Diabetes Research Center, University of Montreal, Montreal, QC, Canada
- CRCHUM–Technopole Angus, 2901 Rachel Est, Montréal, QC, Canada H1W 4A4
- Department of Medicine, University of Montreal, Montreal, QC, Canada
| | - B. Zarrouki
- Montreal Diabetes Research Center, University of Montreal, Montreal, QC, Canada
- CRCHUM–Technopole Angus, 2901 Rachel Est, Montréal, QC, Canada H1W 4A4
- Department of Medicine, University of Montreal, Montreal, QC, Canada
| | - D. K. Hagman
- Montreal Diabetes Research Center, University of Montreal, Montreal, QC, Canada
- CRCHUM–Technopole Angus, 2901 Rachel Est, Montréal, QC, Canada H1W 4A4
- Department of Medicine, University of Montreal, Montreal, QC, Canada
| | - M. G. Latour
- Montreal Diabetes Research Center, University of Montreal, Montreal, QC, Canada
- CRCHUM–Technopole Angus, 2901 Rachel Est, Montréal, QC, Canada H1W 4A4
| | - M. Semache
- Montreal Diabetes Research Center, University of Montreal, Montreal, QC, Canada
- CRCHUM–Technopole Angus, 2901 Rachel Est, Montréal, QC, Canada H1W 4A4
- Department of Biochemistry, University of Montreal, Montreal, QC, Canada
| | - V. Roskens
- Division of Endocrinology, Diabetes and Metabolism, University of Vermont College of Medicine, Burlington, VT, USA
| | - P. C. Moore
- Kovler Diabetes Center, University of Chicago, Chicago, IL, USA
| | - M. Prentki
- Montreal Diabetes Research Center, University of Montreal, Montreal, QC, Canada
- CRCHUM–Technopole Angus, 2901 Rachel Est, Montréal, QC, Canada H1W 4A4
- Department of Nutrition, University of Montreal, Montreal, QC, Canada
- Department of Biochemistry, University of Montreal, Montreal, QC, Canada
| | - C. J. Rhodes
- Kovler Diabetes Center, University of Chicago, Chicago, IL, USA
| | - T. L. Jetton
- Division of Endocrinology, Diabetes and Metabolism, University of Vermont College of Medicine, Burlington, VT, USA
| | - V. Poitout
- Montreal Diabetes Research Center, University of Montreal, Montreal, QC, Canada
- CRCHUM–Technopole Angus, 2901 Rachel Est, Montréal, QC, Canada H1W 4A4,
- Department of Medicine, University of Montreal, Montreal, QC, Canada
- Department of Nutrition, University of Montreal, Montreal, QC, Canada
- Department of Biochemistry, University of Montreal, Montreal, QC, Canada
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Abstract
Autophagy, a ubiquitous catabolic pathway involved in both cell survival and cell death, has been implicated in many age-associated diseases. Recent findings have shown autophagy to be crucial for proper insulin secretion and β-cell viability. Transgenic mice lacking autophagy in their β-cells showed decreased β-cell mass and suppressed glucose-stimulated insulin secretion. Several studies showed that stress can stimulate autophagy in β-cells: the number of autophagosomes is increased in different in vivo models for diabetes, such as db/db mice, mice fed high-fat diet, pdx-1 knockout mice, as well as in in vitro models of glucotoxicity and lipotoxicity. Pharmacological and molecular inhibition of autophagy increases the susceptibility to cell stress, suggesting that autophagy protects against diabetes-relevant stresses. Recent findings, however, question these conclusions. Pancreases of diabetics and β-cells exposed to fatty acids show accumulation of abnormal autophagosome morphology and suppression of lysosomal gene expression suggesting impairment in autophagic turnover. In this review we attempt to give an overview of the data generated by others and by us in view of the possible role of autophagy in diabetes, a role which depending on the conditions, could be beneficial or detrimental in coping with stress.
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Affiliation(s)
- G Las
- Department of Medicine, Section of Molecular Medicine, Boston University School of Medicine, Boston, MA 02118, USA
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Peyot ML, Pepin E, Lamontagne J, Latour MG, Zarrouki B, Lussier R, Pineda M, Jetton TL, Madiraju SRM, Joly E, Prentki M. Beta-cell failure in diet-induced obese mice stratified according to body weight gain: secretory dysfunction and altered islet lipid metabolism without steatosis or reduced beta-cell mass. Diabetes 2010; 59:2178-87. [PMID: 20547980 PMCID: PMC2927940 DOI: 10.2337/db09-1452] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
OBJECTIVE C57Bl/6 mice develop obesity and mild hyperglycemia when fed a high-fat diet (HFD). Although diet-induced obesity (DIO) is a widely studied model of type 2 diabetes, little is known about beta-cell failure in these mice. RESEARCH DESIGN AND METHODS DIO mice were separated in two groups according to body weight gain: low- and high-HFD responders (LDR and HDR). We examined whether mild hyperglycemia in HDR mice is due to reduced beta-cell mass or function and studied islet metabolism and signaling. RESULTS HDR mice were more obese, hyperinsulinemic, insulin resistant, and hyperglycemic and showed a more altered plasma lipid profile than LDR. LDR mice largely compensated insulin resistance, whereas HDR showed perturbed glucose homeostasis. Neither LDR nor HDR mice showed reduced beta-cell mass, altered islet glucose metabolism, and triglyceride deposition. Insulin secretion in response to glucose, KCl, and arginine was impaired in LDR and almost abolished in HDR islets. Palmitate partially restored glucose- and KCl-stimulated secretion. The glucose-induced rise in ATP was reduced in both DIO groups, and the glucose-induced rise in Ca(2+) was reduced in HDR islets relatively to LDR. Glucose-stimulated lipolysis was decreased in LDR and HDR islets, whereas fat oxidation was increased in HDR islets only. Fatty acid esterification processes were markedly diminished, and free cholesterol accumulated in HDR islets. CONCLUSIONS beta-Cell failure in HDR mice is not due to reduced beta-cell mass and glucose metabolism or steatosis but to a secretory dysfunction that is possibly due to altered ATP/Ca(2+) and lipid signaling, as well as free cholesterol deposition.
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Affiliation(s)
- Marie-Line Peyot
- Montreal Diabetes Research Center and CRCHUM, Montreal, QC, Canada.
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45
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Abstract
The complementary disciplines of genomics and proteomics offer better insights into the molecular mechanisms of diseases. While genomics hunts for defining our static genetic substrate, proteomics explores the structure and function of proteins expressed by a cell or tissue type under specified conditions. In the past decade, proteomics has been revolutionized by the application of techniques such as two-dimensional gel electrophoresis (2DGE), mass spectrometry (MS), and protein arrays. These techniques have tremendous potential for biomarker development, target validation, diagnosis, prognosis, and optimization of treatment in medical care, especially in the field of islet and diabetes research. This chapter will highlight the contributions of proteomic technologies toward the dissection of complex network of signaling molecules regulating islet function, the identification of potential biomarkers, and the understanding of mechanisms involved in the pathogenesis of diabetes.
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46
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Abstract
BACKGROUND Elevated plasma free fatty acids (FFA) concentration is predictive of the conversion from normal glucose tolerance and impaired glucose tolerance to diabetes. AIMS To evaluate the effects of prolonged exposure to FFA on basal and glucose-stimulated insulin secretion (GSIS) of pancreatic beta-cell, and to investigate the role of oxidative stress in FFA-induced decrease in beta-cell function. METHODS Rats were assigned to 3 groups and underwent 96-h infusions of normal saline (NS), intralipid plus heparin (IH), or intralipid plus heparin and N-acetylcysteine (IH+NAC). The plasma insulin, malonyldialdehyde (MDA), reduced glutathione (GSH), and oxidized glutathione (GSSG) were measured. In vivo intravenous glucose tolerance test (IVGTT) and ex vivo isolated pancreatic tissues perfusion were performed. RESULTS In IH group GSIS both in IVGTT and perifused pancreatic tissues were impaired (p<0.05), the GSH/GSSG ratio was declined and MDA levels increased (p<0.05), the volume density score of nuclear factor kappaB and inducible nitric oxide synthase in pancreatic islets were increased compared to the NS group (p<0.01). In IH+NAC group, NAC intervention partly restored the GSH/GSSG ratio and MDA level, and improved FFA induced GSIS impairment. CONCLUSION Elevated circulating FFA levels may contribute to causing the abnormalities of pancreatic islet cell function through active oxidative stress and oxidative stress-sensitive signaling pathway, which may play a key role in the development of impaired insulin secretion seen in obese Type 2 diabetes.
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Affiliation(s)
- X Zhang
- Division of Endocrinology and Metabolism, Sichuan University, West China Hospital, Cheng Du, China
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Mccarty MF, Barroso-aranda J, Contreras F. NAPDH oxidase mediates glucolipotoxicity-induced beta cell dysfunction – Clinical implications. Med Hypotheses 2010; 74:596-600. [DOI: 10.1016/j.mehy.2008.09.062] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2008] [Revised: 09/12/2008] [Accepted: 09/27/2008] [Indexed: 01/09/2023]
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Giacca A. From Randle to Lipotoxicity Through Vranic. Can J Diabetes 2010; 34:194-5. [DOI: 10.1016/s1499-2671(10)43019-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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49
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Arellano-Plancarte A, Hernandez-Aranda J, Catt KJ, Olivares-Reyes JA. Angiotensin-induced EGF receptor transactivation inhibits insulin signaling in C9 hepatic cells. Biochem Pharmacol 2009; 79:733-45. [PMID: 19879250 DOI: 10.1016/j.bcp.2009.10.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2009] [Revised: 10/17/2009] [Accepted: 10/19/2009] [Indexed: 01/28/2023]
Abstract
To investigate the potential interactions between the angiotensin II (Ang II) and insulin signaling systems, regulation of IRS-1 phosphorylation and insulin-induced Akt activation by Ang II were examined in clone 9 (C9) hepatocytes. In these cells, Ang II specifically inhibited activation of insulin-induced Akt Thr(308) and its immediate downstream substrate GSK-3alpha/beta in a time-dependent fashion, with approximately 70% reduction at 15 min. These inhibitory actions were associated with increased IRS-1 phosphorylation of Ser(636)/Ser(639) that was prevented by selective blockade of EGFR tyrosine kinase activity with AG1478. Previous studies have shown that insulin-induced phosphorylation of IRS-1 on Ser(636)/Ser(639) is mediated mainly by the PI3K/mTOR/S6K-1 sequence. Studies with specific inhibitors of PI3K (wortmannin) and mTOR (rapamycin) revealed that Ang II stimulates IRS-1 phosphorylation of Ser(636)/Ser(639) via the PI3K/mTOR/S6K-1 pathway. Both inhibitors blocked the effect of Ang II on insulin-induced activation of Akt. Studies using the specific MEK inhibitor, PD98059, revealed that ERK1/2 activation also mediates Ang II-induced S6K-1 and IRS-1 phosphorylation, and the impairment of Akt Thr(308) and GSK-3alpha/beta phosphorylation. Further studies with selective inhibitors showed that PI3K activation was upstream of ERK, suggesting a new mechanism for Ang II-induced impairment of insulin signaling. These findings indicate that Ang II has a significant role in the development of insulin resistance by a mechanism that involves EGFR transactivation and the PI3K/ERK1/2/mTOR-S6K-1 pathway.
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Affiliation(s)
- Araceli Arellano-Plancarte
- Department of Biochemistry, Center for Research and Advanced Studies of the National Polytechnic Institute, Cinvestav-IPN, A.P. 14-740, Mexico, 07360 D.F., Mexico
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Poitout V, Amyot J, Semache M, Zarrouki B, Hagman D, Fontés G. Glucolipotoxicity of the pancreatic beta cell. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1801:289-98. [PMID: 19715772 DOI: 10.1016/j.bbalip.2009.08.006] [Citation(s) in RCA: 264] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2009] [Revised: 08/13/2009] [Accepted: 08/13/2009] [Indexed: 02/07/2023]
Abstract
The concept of glucolipotoxicity refers to the combined, deleterious effects of elevated glucose and fatty acid levels on pancreatic beta-cell function and survival. Significant progress has been made in recent years towards a better understanding of the cellular and molecular basis of glucolipotoxicity in the beta cell. The permissive effect of elevated glucose on the detrimental actions of fatty acids stems from the influence of glucose on intracellular fatty acid metabolism, promoting the synthesis of cellular lipids. The combination of excessive levels of fatty acids and glucose therefore leads to decreased insulin secretion, impaired insulin gene expression, and beta-cell death by apoptosis, all of which probably have distinct underlying mechanisms. Recent studies from our laboratory have identified several pathways implicated in fatty acid inhibition of insulin gene expression, including the extracellular-regulated kinase (ERK1/2) pathway, the metabolic sensor Per-Arnt-Sim kinase (PASK), and the ATF6 branch of the unfolded protein response. We have also confirmed in vivo in rats that the decrease in insulin gene expression is an early defect which precedes any detectable abnormality in insulin secretion. While the role of glucolipotoxicity in humans is still debated, the inhibitory effects of chronically elevated fatty acid levels has been clearly demonstrated in several studies, at least in individuals genetically predisposed to developing type 2 diabetes. It is therefore likely that glucolipotoxicity contributes to beta-cell failure in type 2 diabetes as well as to the decline in beta-cell function observed after the onset of the disease.
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Affiliation(s)
- Vincent Poitout
- Montreal Diabetes Research Center, CRCHUM, Department of Medicine, University of Montreal, Montreal, QC, Canada.
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