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Wang KY, Wu SM, Yao ZJ, Zhu YX, Han X. Insufficient TRPM5 Mediates Lipotoxicity-induced Pancreatic β-cell Dysfunction. Curr Med Sci 2024; 44:346-354. [PMID: 38517672 DOI: 10.1007/s11596-023-2795-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 08/28/2023] [Indexed: 03/24/2024]
Abstract
OBJECTIVE While the reduction of transient receptor potential channel subfamily M member 5 (TRPM5) has been reported in islet cells from type 2 diabetic (T2D) mouse models, its role in lipotoxicity-induced pancreatic β-cell dysfunction remains unclear. This study aims to study its role. METHODS Pancreas slices were prepared from mice subjected to a high-fat-diet (HFD) at different time points, and TRPM5 expression in the pancreatic β cells was examined using immunofluorescence staining. Glucose-stimulated insulin secretion (GSIS) defects caused by lipotoxicity were mimicked by saturated fatty acid palmitate (Palm). Primary mouse islets and mouse insulinoma MIN6 cells were treated with Palm, and the TRPM5 expression was detected using qRT-PCR and Western blotting. Palm-induced GSIS defects were measured following siRNA-based Trpm5 knockdown. The detrimental effects of Palm on primary mouse islets were also assessed after overexpressing Trpm5 via an adenovirus-derived Trpm5 (Ad-Trpm5). RESULTS HFD feeding decreased the mRNA levels and protein expression of TRPM5 in mouse pancreatic islets. Palm reduced TRPM5 protein expression in a time- and dose-dependent manner in MIN6 cells. Palm also inhibited TRPM5 expression in primary mouse islets. Knockdown of Trpm5 inhibited insulin secretion upon high glucose stimulation but had little effect on insulin biosynthesis. Overexpression of Trpm5 reversed Palm-induced GSIS defects and the production of functional maturation molecules unique to β cells. CONCLUSION Our findings suggest that lipotoxicity inhibits TRPM5 expression in pancreatic β cells both in vivo and in vitro and, in turn, drives β-cell dysfunction.
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Affiliation(s)
- Kai-Yuan Wang
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, 211166, China
| | - Shi-Mei Wu
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, 211166, China
| | - Zheng-Jian Yao
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, 211166, China
| | - Yun-Xia Zhu
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, 211166, China.
| | - Xiao Han
- Key Laboratory of Human Functional Genomics of Jiangsu Province, Department of Biochemistry and Molecular Biology, Nanjing Medical University, Nanjing, 211166, China.
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Xing J, Chen C. Hyperinsulinemia: beneficial or harmful or both on glucose homeostasis. Am J Physiol Endocrinol Metab 2022; 323:E2-E7. [PMID: 35635329 DOI: 10.1152/ajpendo.00441.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Insulin, a principal anabolic hormone produced by pancreatic β-cells, has a primary function of storage of nutrients following excessive energy intake. Pre- or early type 2 diabetes stages present hyperinsulinemia (β-cell dysfunction) and insulin resistance. Initiation of hyperinsulinemia is triggered by a loss of first-phase glucose-stimulated insulin secretion with altered membrane ion channel distribution. More factors, including insulin resistance and excessive proliferation of β-cells, deteriorate the hyperinsulinemia, whereas the hyperinsulinemia contributes to further development of insulin resistance and type 2 diabetes; to develop eventually late-stage diabetes with absolute insulin deficiency. In this mini-review, the major focus was put on the causes and pathophysiology of hyperinsulinemia, and the metabolic consequences and current treatment of hyperinsulinemia were discussed. The data used in this narrative review were collected mainly from relevant discoveries in the past 3 years.
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Affiliation(s)
- JingJing Xing
- School of Biomedical Sciences, University of Queensland, Brisbane, Queensland, Australia
| | - Chen Chen
- School of Biomedical Sciences, University of Queensland, Brisbane, Queensland, Australia
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Yan Z, Fortunato M, Shyr ZA, Clark AL, Fuess M, Nichols CG, Remedi MS. Genetic Reduction of Glucose Metabolism Preserves Functional β-Cell Mass in KATP-Induced Neonatal Diabetes. Diabetes 2022; 71:1233-1245. [PMID: 35294000 PMCID: PMC9163553 DOI: 10.2337/db21-0992] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 03/09/2022] [Indexed: 11/13/2022]
Abstract
β-Cell failure and loss of β-cell mass are key events in diabetes progression. Although insulin hypersecretion in early stages has been implicated in β-cell exhaustion/failure, loss of β-cell mass still occurs in KATP gain-of-function (GOF) mouse models of human neonatal diabetes in the absence of insulin secretion. Thus, we hypothesize that hyperglycemia-induced increased β-cell metabolism is responsible for β-cell failure and that reducing glucose metabolism will prevent loss of β-cell mass. To test this, KATP-GOF mice were crossed with mice carrying β-cell-specific glucokinase haploinsufficiency (GCK+/-), to genetically reduce glucose metabolism. As expected, both KATP-GOF and KATP-GOF/GCK+/- mice showed lack of glucose-stimulated insulin secretion. However, KATP-GOF/GCK+/- mice demonstrated markedly reduced blood glucose, delayed diabetes progression, and improved glucose tolerance compared with KATP-GOF mice. In addition, decreased plasma insulin and content, increased proinsulin, and augmented plasma glucagon observed in KATP-GOF mice were normalized to control levels in KATP-GOF/GCK+/- mice. Strikingly, KATP-GOF/GCK+/- mice demonstrated preserved β-cell mass and identity compared with the marked decrease in β-cell identity and increased dedifferentiation observed in KATP-GOF mice. Moreover KATP-GOF/GCK+/- mice demonstrated restoration of body weight and liver and brown/white adipose tissue mass and function and normalization of physical activity and metabolic efficiency compared with KATP-GOF mice. These results demonstrate that decreasing β-cell glucose signaling can prevent glucotoxicity-induced loss of insulin content and β-cell failure independently of compensatory insulin hypersecretion and β-cell exhaustion.
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Affiliation(s)
- Zihan Yan
- Division of Endocrinology, Metabolism and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Manuela Fortunato
- Division of Endocrinology, Metabolism and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Zeenat A. Shyr
- Division of Endocrinology, Metabolism and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Amy L. Clark
- Department of Pediatrics, Washington University School of Medicine, St. Louis, MO
| | - Matt Fuess
- Division of Endocrinology, Metabolism and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO
| | - Colin G. Nichols
- Deparment of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, MO
| | - Maria S. Remedi
- Division of Endocrinology, Metabolism and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO
- Deparment of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, MO
- Corresponding author: Maria S. Remedi,
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Clark AL, Yan Z, Chen SX, Shi V, Kulkarni DH, Diwan A, Remedi MS. High-fat diet prevents the development of autoimmune diabetes in NOD mice. Diabetes Obes Metab 2021; 23:2455-2465. [PMID: 34212475 PMCID: PMC8490276 DOI: 10.1111/dom.14486] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 06/21/2021] [Accepted: 06/30/2021] [Indexed: 12/20/2022]
Abstract
AIMS Type 1 diabetes (T1D) has a strong genetic predisposition and requires an environmental trigger to initiate the beta-cell autoimmune destruction. The rate of childhood obesity has risen in parallel to the proportion of T1D, suggesting high-fat diet (HFD)/obesity as potential environmental triggers for autoimmune diabetes. To explore this, non-obese diabetic (NOD) mice were subjected to HFD and monitored for the development of diabetes, insulitis and beta-cell stress. MATERIALS AND METHODS Four-week-old female NOD mice were placed on HFD (HFD-NOD) or standard chow-diet. Blood glucose was monitored weekly up to 40 weeks of age, and glucose- and insulin-tolerance tests performed at 4, 10 and 15 weeks. Pancreata and islets were analysed for insulin secretion, beta-cell mass, inflammation, insulitis and endoplasmic reticulum stress markers. Immune cell levels were measured in islets and spleens. Stool microbiome was analysed at age 4, 8 and 25 weeks. RESULTS At early ages, HFD-NOD mice showed a significant increase in body weight, glucose intolerance and insulin resistance; but paradoxically, they were protected from developing diabetes. This was accompanied by increased insulin secretion and beta-cell mass, decreased insulitis, increased splenic T-regulatory cells and altered stool microbiome. CONCLUSIONS This study shows that HFD protects NOD mice from autoimmune diabetes and preserves beta-cell mass and function through alterations in gut microbiome, increased T-regulatory cells and decreased insulitis. Further studies into the exact mechanism of HFD-mediated prevention of diabetes in NOD mice could potentially lead to interventions to prevent or delay T1D development in humans.
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Affiliation(s)
- Amy L. Clark
- Department of PediatricsWashington University in St LouisSt LouisMissouriUSA
| | - Zihan Yan
- Department of Internal Medicine, Endocrinology, Metabolism and Lipid research DivisionWashington University in St LouisSt LouisMissouriUSA
| | - Sophia X. Chen
- Department of Internal Medicine, Endocrinology, Metabolism and Lipid research DivisionWashington University in St LouisSt LouisMissouriUSA
| | - Victoria Shi
- Department of Internal Medicine, Endocrinology, Metabolism and Lipid research DivisionWashington University in St LouisSt LouisMissouriUSA
| | - Devesha H. Kulkarni
- Department of Internal MedicineWashington University in St LouisSt LouisMissouriUSA
| | - Abhinav Diwan
- Department of Internal Medicine‐Cardiovascular DivisionWashington University in St LouisSt LouisMissouriUSA
- John Cochran VA Medical Center‐Cardiovascular DivisionSt LouisMissouriUSA
| | - Maria S. Remedi
- Department of Internal Medicine, Endocrinology, Metabolism and Lipid research DivisionWashington University in St LouisSt LouisMissouriUSA
- Department of Cell Biology and PhysiologyWashington University in St LouisSt LouisMissouriUSA
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Shyr ZA, Wang Z, York NW, Nichols CG, Remedi MS. The role of membrane excitability in pancreatic β-cell glucotoxicity. Sci Rep 2019; 9:6952. [PMID: 31061431 PMCID: PMC6502887 DOI: 10.1038/s41598-019-43452-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 01/11/2019] [Indexed: 01/09/2023] Open
Abstract
Persistent hyperglycemia is causally associated with pancreatic β-cell dysfunction and loss of pancreatic insulin. Glucose normally enhances β-cell excitability through inhibition of KATP channels, opening of voltage-dependent calcium channels, increased [Ca2+]i, which triggers insulin secretion. Glucose-dependent excitability is lost in islets from KATP-knockout (KATP-KO) mice, in which β-cells are permanently hyperexcited, [Ca2+]i, is chronically elevated and insulin is constantly secreted. Mouse models of human neonatal diabetes in which KATP gain-of-function mutations are expressed in β-cells (KATP-GOF) also lose the link between glucose metabolism and excitation-induced insulin secretion, but in this case KATP-GOF β-cells are chronically underexcited, with permanently low [Ca2+]i and lack of glucose-dependent insulin secretion. We used KATP-GOF and KATP-KO islets to examine the role of altered-excitability in glucotoxicity. Wild-type islets showed rapid loss of insulin content when chronically incubated in high-glucose, an effect that was reversed by subsequently switching to low glucose media. In contrast, hyperexcitable KATP-KO islets lost insulin content in both low- and high-glucose, while underexcitable KATP-GOF islets maintained insulin content in both conditions. Loss of insulin content in chronic excitability was replicated by pharmacological inhibition of KATP by glibenclamide, The effects of hyperexcitable and underexcitable islets on glucotoxicity observed in in vivo animal models are directly opposite to the effects observed in vitro: we clearly demonstrate here that in vitro, hyperexcitability is detrimental to islets whereas underexcitability is protective.
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Affiliation(s)
- Zeenat A Shyr
- Department of Medicine, Division of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, Missouri, 63110, USA
| | - Zhiyu Wang
- Department of Medicine, Division of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, Missouri, 63110, USA.,Endocrine Consultants Northwest, Franciscan Medical Group, 1628 South Mildred St. Suite 104, Tacoma, WA, 98465, USA
| | - Nathaniel W York
- Department of Cell Biology and Physiology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, Missouri, 63110, USA
| | - Colin G Nichols
- Department of Cell Biology and Physiology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, Missouri, 63110, USA.,Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, Missouri, 63110, USA
| | - Maria S Remedi
- Department of Medicine, Division of Endocrinology, Metabolism and Lipid Research, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, Missouri, 63110, USA. .,Department of Cell Biology and Physiology, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, Missouri, 63110, USA. .,Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, Missouri, 63110, USA.
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Al-Kuraishy HM, Al-Gareeb AI. Effects of rosuvastatin on metabolic profile: Versatility of dose-dependent effect. J Adv Pharm Technol Res 2019; 10:33-38. [PMID: 30815386 PMCID: PMC6383350 DOI: 10.4103/japtr.japtr_330_18] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Obesity refers to an excess of body fat content causing metabolic and inflammatory disorders. Therefore, the aim of the present study was to investigate dose-dependent effect of rosuvastatin on the metabolic profile of diet-induced obesity in mice model study. A total number of 40 male Albino Swiss mice were used which divided into Group I: Control group, fed normal diet for 8 weeks (n = 10); Group II: High-fat diet (HFD) group, fed on HFD for 8 weeks (n = 10); Group III: HFD + 20 mg/kg rosuvastatin for 8 weeks (n = 10); and Group IV: HFD +40 mg/kg rosuvastatin for 8 weeks (n = 10). Anthropometric and biochemical parameters were estimated, including fasting blood glucose, lipid profile, fasting insulin, and glucose tolerance test (GTT). Mice on HFD fed showed a significant increase in the insulin resistance, body weight, deterioration of lipid profile and significant reduction in the β-cell function, and insulin sensitivity compared to the control P < 0.05. GTT and blood glucose level were significantly high in HFD fed group compared to the control group P < 0.05. Rosuvastatin in a dose of 40 mg/kg illustrated better effect than 20 mg/kg on the glucometabolic profile P < 0.05. Rosuvastatin may has a potential effect on reduction of glucometabolic changes induced by HFD with significant amelioration of pancreatic β-cell function in dose-dependent manner.
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Affiliation(s)
- Hayder M Al-Kuraishy
- Department of Pharmacology, Toxicology and Medicine, College of Medicine, Al-Mustansiriya University, Baghdad, Iraq
| | - Ali I Al-Gareeb
- Department of Pharmacology, Toxicology and Medicine, College of Medicine, Al-Mustansiriya University, Baghdad, Iraq
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