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Wei C, Zhang Z, Fu Q, He Y, Yang T, Sun M. The reversible effects of free fatty acids on sulfonylurea-stimulated insulin secretion are related to the expression and dynamin-mediated endocytosis of KATP channels in pancreatic β cells. Endocr Connect 2023; 12:e220221. [PMID: 36398885 PMCID: PMC9782416 DOI: 10.1530/ec-22-0221] [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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 11/18/2022] [Indexed: 11/19/2022]
Abstract
Objective Lipotoxicity-induced pancreatic β cell-dysfunction results in decreased insulin secretion in response to multiple stimulus. In this study, we investigated the reversible effects of palmitate (PA) or oleate (OA) on insulin secretion and the relationship with pancreatic β-cell ATP-sensitive potassium (KATP) channels. Methods MIN6 cells were treated with PA and OA for 48 h and then washed out for 24 h to determine the changes in expression and endocytosis of the KATP channels and glucose-stimulated insulin secretion (GSIS) and sulfonylurea-stimulated insulin secretion (SU-SIS). Results MIN6 cells exposed to PA or OA showed both impaired GSIS and SU-SIS; the former was not restorable, while the latter was reversible with washout of PA or OA. Decreased expressions of both total and surface Kir6.2 and SUR1 and endocytosis of KATP channels were observed, which were also recoverable after washout. When MIN6 cells exposed to free fatty acids (FFAs) were cotreated with 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) or dynasore, we found that endocytosis of KATP channels did not change significantly by AICAR but was almost completely blocked by dynasore. Meanwhile, the inhibition of endocytosis of KATP channels after washout could be activated by PIP2. The recovery of SU-SIS after washout was significantly weakened by PIP2, but the decrease of SU-SIS induced by FFAs was not alleviated by dynasore. Conclusions FFAs can cause reversible impairment of SU-SIS on pancreatic β cells. The reversibility of the effects is partial because of the changes of expression and endocytosis of Kir6.2 and SUR1 which was mediated by dynamin.
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Affiliation(s)
- Chenmin Wei
- Department of Endocrinology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
- Department of Endocrinology, The Affiliated Jiangning Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Zichen Zhang
- Department of Endocrinology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Qi Fu
- Department of Endocrinology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Yunqiang He
- Department of Endocrinology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Tao Yang
- Department of Endocrinology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Min Sun
- Department of Endocrinology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
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Römer A, Rawat D, Linn T, Petry SF. Preparation of fatty acid solutions exerts significant impact on experimental outcomes in cell culture models of lipotoxicity. Biol Methods Protoc 2022; 7:bpab023. [PMID: 35036572 PMCID: PMC8754478 DOI: 10.1093/biomethods/bpab023] [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] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 11/25/2021] [Accepted: 11/30/2021] [Indexed: 11/14/2022] Open
Abstract
Free fatty acids are essentially involved in the pathogenesis of chronic diseases such as diabetes mellitus, non-alcoholic fatty liver disease, and cardiovascular disease. They promote mitochondrial dysfunction, oxidative stress, respiratory chain uncoupling, and endoplasmic reticulum stress and modulate stress-sensitive pathways. These detrimental biological effects summarized as lipotoxicity mainly depend on fatty acid carbon chain length, degree of unsaturation, concentration, and treatment time. Preparation of fatty acid solutions involves dissolving and complexing. Solvent toxicity and concentration, amount of bovine serum albumin (BSA), and ratio of albumin to fatty acids can vary significantly between equal concentrations, mediating considerable harmful effects and/or interference with certain assays such as 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). Herein, we studied the impact of commonly used solvents ethanol and dimethyl sulfoxide and varying concentrations of BSA directly and in solution with oleic acid on MTT to formazan conversion, adenosine triphosphate level, and insulin content and secretion of murine β-cell line MIN6 employing different treatment duration. Our data show that experimental outcomes and assay readouts can be significantly affected by mere preparation of fatty acid solutions and should thus be carefully considered and described in detail to ensure comparability and distinct evaluation of data.
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Affiliation(s)
- Axel Römer
- Clinical Research Unit, Center of Internal Medicine, Justus Liebig University Giessen, 35392 Giessen, Germany
| | - Divya Rawat
- Clinical Research Unit, Center of Internal Medicine, Justus Liebig University Giessen, 35392 Giessen, Germany
| | - Thomas Linn
- Clinical Research Unit, Center of Internal Medicine, Justus Liebig University Giessen, 35392 Giessen, Germany
| | - Sebastian F Petry
- Clinical Research Unit, Center of Internal Medicine, Justus Liebig University Giessen, 35392 Giessen, Germany
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Römer A, Linn T, Petry SF. Lipotoxic Impairment of Mitochondrial Function in β-Cells: A Review. Antioxidants (Basel) 2021; 10:293. [PMID: 33672062 DOI: 10.3390/antiox10020293] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 02/06/2021] [Accepted: 02/11/2021] [Indexed: 02/08/2023] Open
Abstract
Lipotoxicity is a major contributor to type 2 diabetes mainly promoting mitochondrial dysfunction. Lipotoxic stress is mediated by elevated levels of free fatty acids through various mechanisms and pathways. Impaired peroxisome proliferator-activated receptor (PPAR) signaling, enhanced oxidative stress levels, and uncoupling of the respiratory chain result in ATP deficiency, while β-cell viability can be severely impaired by lipotoxic modulation of PI3K/Akt and mitogen-activated protein kinase (MAPK)/extracellular-signal-regulated kinase (ERK) pathways. However, fatty acids are physiologically required for an unimpaired β-cell function. Thus, preparation, concentration, and treatment duration determine whether the outcome is beneficial or detrimental when fatty acids are employed in experimental setups. Further, ageing is a crucial contributor to β-cell decay. Cellular senescence is connected to loss of function in β-cells and can further be promoted by lipotoxicity. The potential benefit of nutrients has been broadly investigated, and particularly polyphenols were shown to be protective against both lipotoxicity and cellular senescence, maintaining the physiology of β-cells. Positive effects on blood glucose regulation, mitigation of oxidative stress by radical scavenging properties or regulation of antioxidative enzymes, and modulation of apoptotic factors were reported. This review summarizes the significance of lipotoxicity and cellular senescence for mitochondrial dysfunction in the pancreatic β-cell and outlines potential beneficial effects of plant-based nutrients by the example of polyphenols.
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Ježek P, Jabůrek M, Plecitá-Hlavatá L. Contribution of Oxidative Stress and Impaired Biogenesis of Pancreatic β-Cells to Type 2 Diabetes. Antioxid Redox Signal 2019; 31:722-751. [PMID: 30450940 PMCID: PMC6708273 DOI: 10.1089/ars.2018.7656] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [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: 10/15/2018] [Accepted: 11/05/2018] [Indexed: 12/14/2022]
Abstract
Significance: Type 2 diabetes development involves multiple changes in β-cells, related to the oxidative stress and impaired redox signaling, beginning frequently by sustained overfeeding due to the resulting lipotoxicity and glucotoxicity. Uncovering relationships among the dysregulated metabolism, impaired β-cell "well-being," biogenesis, or cross talk with peripheral insulin resistance is required for elucidation of type 2 diabetes etiology. Recent Advances: It has been recognized that the oxidative stress, lipotoxicity, and glucotoxicity cannot be separated from numerous other cell pathology events, such as the attempted compensation of β-cell for the increased insulin demand and dynamics of β-cell biogenesis and its "reversal" at dedifferentiation, that is, from the concomitantly decreasing islet β-cell mass (also due to transdifferentiation) and low-grade islet or systemic inflammation. Critical Issues: At prediabetes, the compensation responses of β-cells, attempting to delay the pathology progression-when exaggerated-set a new state, in which a self-checking redox signaling related to the expression of Ins gene expression is impaired. The resulting altered redox signaling, diminished insulin secretion responses to various secretagogues including glucose, may lead to excretion of cytokines or chemokines by β-cells or excretion of endosomes. They could substantiate putative stress signals to the periphery. Subsequent changes and lasting glucolipotoxicity promote islet inflammatory responses and further pathology spiral. Future Directions: Should bring an understanding of the β-cell self-checking and related redox signaling, including the putative stress signal to periphery. Strategies to cure or prevent type 2 diabetes could be based on the substitution of the "wrong" signal by the "correct" self-checking signal.
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Affiliation(s)
- Petr Ježek
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Martin Jabůrek
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Lydie Plecitá-Hlavatá
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
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Xin Y, Wang Y, Chi J, Zhu X, Zhao H, Zhao S, Wang Y. Elevated free fatty acid level is associated with insulin-resistant state in nondiabetic Chinese people. Diabetes Metab Syndr Obes 2019; 12:139-147. [PMID: 30705599 PMCID: PMC6342222 DOI: 10.2147/dmso.s186505] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Free fatty acids (FFAs) are associated with insulin secretion and insulin resistance. However, the associations among FFAs, obesity, and progression from a normal to a prediabetic state are unclear. METHODS Nondiabetic subjects (5,952) were divided in two groups according to their body mass index (BMI): obese subjects (BMI ≥24 kg/m2) and nonobese subjects (BMI <24 kg/m2). Clinical and multiple glucolipid metabolism data were collected. The homeostasis model assessment for insulin resistance (HOMA-IR) and β-cell function (HOMA-β) was used. HbA1c level between 5.7% and 6.4% was considered prediabetic. Nonparametric tests, one-way ANOVA, and linear correlation analysis were performed. R and SPSS 23.0 software programs were used to analyze the results. RESULTS A U-shaped relationship between FFAs and HOMA-IR was observed. After adjusting for potential confounders, the turning points of FFA levels in the curves were 0.54 mmol/L in the nonobese group and 0.61 mmol/L in the obese group. HOMA-IR levels decreased with increasing FFA concentrations before the turning points (regression coefficient [β]= - 0.9, P=0.0111, for the nonobese group; β=0.2, P=0.5094, for the obese group) and then increased (β=0.9, P=0.0069, for the nonobese group; β=1.5, P=0.0263 for the obese group) after the points. Additionally, our study also identified that FFAs were associated with the prediabetes status in obese individuals. CONCLUSION FFA levels were associated with insulin resistance in nondiabetic subjects, and HOMA-IR in nonobese individuals was more sensitive to FFA changes. Monitoring and controlling plasma FFA levels in obese subjects is significant in decreasing insulin resistance and preventing diabetes.
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Affiliation(s)
- Yanlu Xin
- Department of Endocrinology and Metabolism, Affiliated Hospital of Qingdao University, Qingdao, China, ;
| | - Yunyang Wang
- Department of Endocrinology and Metabolism, Affiliated Hospital of Qingdao University, Qingdao, China, ;
| | - Jingwei Chi
- Laboratory of Thyroid Disease, Affiliated Hospital of Qingdao University, Qingdao, China,
| | - Xvhua Zhu
- Department of Endocrinology and Metabolism, Second People's Hospital of Qingdao West Coast, Qingdao, China
| | - Hui Zhao
- Department of Endocrinology and Metabolism, Hiser Medical Center of Qingdao, Qingdao, China
| | - Shihua Zhao
- Department of Endocrinology and Metabolism, Affiliated Hospital of Qingdao University, Qingdao, China, ;
- Laboratory of Thyroid Disease, Affiliated Hospital of Qingdao University, Qingdao, China,
| | - Yangang Wang
- Department of Endocrinology and Metabolism, Affiliated Hospital of Qingdao University, Qingdao, China, ;
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Ježek P, Jabůrek M, Holendová B, Plecitá-Hlavatá L. Fatty Acid-Stimulated Insulin Secretion vs. Lipotoxicity. Molecules 2018; 23:E1483. [PMID: 29921789 DOI: 10.3390/molecules23061483] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 06/13/2018] [Accepted: 06/15/2018] [Indexed: 12/29/2022] Open
Abstract
Fatty acid (FA)-stimulated insulin secretion (FASIS) is reviewed here in contrast to type 2 diabetes etiology, resulting from FA overload, oxidative stress, intermediate hyperinsulinemia, and inflammation, all converging into insulin resistance. Focusing on pancreatic islet β-cells, we compare the physiological FA roles with the pathological ones. Considering FAs not as mere amplifiers of glucose-stimulated insulin secretion (GSIS), but as parallel insulin granule exocytosis inductors, partly independent of the KATP channel closure, we describe the FA initiating roles in the prediabetic state that is induced by retardations in the glycerol-3-phosphate (glucose)-promoted glycerol/FA cycle and by the impaired GPR40/FFA1 (free FA1) receptor pathway, specifically in its amplification by the redox-activated mitochondrial phospholipase, iPLA2γ. Also, excessive dietary FAs stimulate intestine enterocyte incretin secretion, further elevating GSIS, even at low glucose levels, thus contributing to diabetic hyperinsulinemia. With overnutrition and obesity, the FA overload causes impaired GSIS by metabolic dysbalance, paralleled by oxidative and metabolic stress, endoplasmic reticulum stress and numerous pro-apoptotic signaling, all leading to decreased β-cell survival. Lipotoxicity is exerted by saturated FAs, whereas ω-3 polyunsaturated FAs frequently exert antilipotoxic effects. FA-facilitated inflammation upon the recruitment of excess M1 macrophages into islets (over resolving M2 type), amplified by cytokine and chemokine secretion by β-cells, leads to an inevitable failure of pancreatic β-cells.
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Abstract
Polyunsaturated Fatty acids have multiple effects in peripheral tissues and pancreatic beta cell function. The n-3 Polyunsaturated Fatty acids prevent and reverse high-fat-diet induced adipose tissue inflammation and insulin resistance. Insulin secretion is stimulated by glucose, amino acids, and glucagon- like peptide-1 in tissue containing high levels of n-3 Polyunsaturated Fatty acids than lower level of n-3 Polyunsaturated Fatty acids. Also, n-3 Polyunsaturated Fatty acids led to decreased production of prostaglandin, which in turn contributed to the elevation of insulin secretion. N-3 polyunsaturated fatty acids prevent cytokine-induced cell death in pancreatic islets. Supplementation of n-3 Polyunsaturated Fatty acids for human subjects prevent beta cell destruction and insulin resistance. It also enhances insulin secretion, reduction in lipid profiles and glucose concentration particularly in type II diabetes patients. Therefore there should be a focus on the treatment mechanism of insulin related obesity and diabetes by n-3 polyunsaturated fatty acids.
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Affiliation(s)
- Habtamu Wondifraw Baynes
- Department of Clinical Chemistry, School of Biomedical and Laboratory Sciences, College of Medicine and Health Sciences, University of Gondar, Northwest Ethiopia
| | - Seifu Mideksa
- Clinical Chemistry laboratory, Ayder Comprehensive Specialized Hospital, Mekelle, Northern, Ethiopia
| | - Sintayehu Ambachew
- Department of Clinical Chemistry, School of Biomedical and Laboratory Sciences, College of Medicine and Health Sciences, University of Gondar, Northwest Ethiopia
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