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Rivera Nieves AM, Wauford BM, Fu A. Mitochondrial bioenergetics, metabolism, and beyond in pancreatic β-cells and diabetes. Front Mol Biosci 2024; 11:1354199. [PMID: 38404962 PMCID: PMC10884328 DOI: 10.3389/fmolb.2024.1354199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Accepted: 01/17/2024] [Indexed: 02/27/2024] Open
Abstract
In Type 1 and Type 2 diabetes, pancreatic β-cell survival and function are impaired. Additional etiologies of diabetes include dysfunction in insulin-sensing hepatic, muscle, and adipose tissues as well as immune cells. An important determinant of metabolic health across these various tissues is mitochondria function and structure. This review focuses on the role of mitochondria in diabetes pathogenesis, with a specific emphasis on pancreatic β-cells. These dynamic organelles are obligate for β-cell survival, function, replication, insulin production, and control over insulin release. Therefore, it is not surprising that mitochondria are severely defective in diabetic contexts. Mitochondrial dysfunction poses challenges to assess in cause-effect studies, prompting us to assemble and deliberate the evidence for mitochondria dysfunction as a cause or consequence of diabetes. Understanding the precise molecular mechanisms underlying mitochondrial dysfunction in diabetes and identifying therapeutic strategies to restore mitochondrial homeostasis and enhance β-cell function are active and expanding areas of research. In summary, this review examines the multidimensional role of mitochondria in diabetes, focusing on pancreatic β-cells and highlighting the significance of mitochondrial metabolism, bioenergetics, calcium, dynamics, and mitophagy in the pathophysiology of diabetes. We describe the effects of diabetes-related gluco/lipotoxic, oxidative and inflammation stress on β-cell mitochondria, as well as the role played by mitochondria on the pathologic outcomes of these stress paradigms. By examining these aspects, we provide updated insights and highlight areas where further research is required for a deeper molecular understanding of the role of mitochondria in β-cells and diabetes.
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Affiliation(s)
- Alejandra María Rivera Nieves
- Diabetes Center of Excellence, University of Massachusetts Chan Medical School, Worcester, MA, United States
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA, United States
| | - Brian Michael Wauford
- Diabetes Center of Excellence, University of Massachusetts Chan Medical School, Worcester, MA, United States
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA, United States
| | - Accalia Fu
- Diabetes Center of Excellence, University of Massachusetts Chan Medical School, Worcester, MA, United States
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA, United States
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You S, Xu J, Yin Z, Wu B, Wang P, Hao M, Cheng C, Liu M, Zhao Y, Jia P, Jiang H, Li D, Cao L, Zhang X, Zhang Y, Sun Y, Zhang N. Down-regulation of WWP2 aggravates Type 2 diabetes mellitus-induced vascular endothelial injury through modulating ubiquitination and degradation of DDX3X. Cardiovasc Diabetol 2023; 22:107. [PMID: 37149668 PMCID: PMC10164326 DOI: 10.1186/s12933-023-01818-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Accepted: 03/29/2023] [Indexed: 05/08/2023] Open
Abstract
BACKGROUND Endothelial injury caused by Type 2 diabetes mellitus (T2DM) is considered as a mainstay in the pathophysiology of diabetic vascular complications (DVCs). However, the molecular mechanism of T2DM-induced endothelial injury remains largely unknown. Here, we found that endothelial WW domain-containing E3 ubiquitin protein ligase 2 (WWP2) act as a novel regulator for T2DM-induced vascular endothelial injury through modulating ubiquitination and degradation of DEAD-box helicase 3 X-linked (DDX3X). METHODS Single-cell transcriptome analysis was used to evaluate WWP2 expression in vascular endothelial cells of T2DM patients and healthy controls. Endothelial-specific Wwp2 knockout mice were used to investigate the effect of WWP2 on T2DM-induced vascular endothelial injury. In vitro loss- and gain-of-function studies were performed to assess the function of WWP2 on cell proliferation and apoptosis of human umbilical vein endothelial cells. The substrate protein of WWP2 was verified using mass spectrometry, coimmunoprecipitation assays and immunofluorescence assays. The mechanism of WWP2 regulation on substrate protein was investigated by pulse-chase assay and ubiquitination assay. RESULTS The expression of WWP2 was significantly down-regulated in vascular endothelial cells during T2DM. Endothelial-specific Wwp2 knockout in mice significantly aggravated T2DM-induced vascular endothelial injury and vascular remodeling after endothelial injury. Our in vitro experiments showed that WWP2 protected against endothelial injury by promoting cell proliferation and inhibiting apoptosis in ECs. Mechanically, we found that WWP2 is down-regulated in high glucose and palmitic acid (HG/PA)-induced ECs due to c-Jun N-terminal kinase (JNK) activation, and uncovered that WWP2 suppresses HG/PA-induced endothelial injury by catalyzing K63-linked polyubiquitination of DDX3X and targeting it for proteasomal degradation. CONCLUSION Our studies revealed the key role of endothelial WWP2 and the fundamental importance of the JNK-WWP2-DDX3X regulatory axis in T2DM-induced vascular endothelial injury, suggesting that WWP2 may serve as a new therapeutic target for DVCs.
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Affiliation(s)
- Shilong You
- Department of Cardiology, The First Hospital of China Medical University, 155 Nanjing North Street, Heping District, Shenyang, 110001, Liaoning Province, People's Republic of China
| | - Jiaqi Xu
- Department of Cardiology, The First Hospital of China Medical University, 155 Nanjing North Street, Heping District, Shenyang, 110001, Liaoning Province, People's Republic of China
| | - Zeyu Yin
- Department of Cardiology, The First Hospital of China Medical University, 155 Nanjing North Street, Heping District, Shenyang, 110001, Liaoning Province, People's Republic of China
| | - Boquan Wu
- Department of Cardiology, The First Hospital of China Medical University, 155 Nanjing North Street, Heping District, Shenyang, 110001, Liaoning Province, People's Republic of China
| | - Pengbo Wang
- Department of Cardiology, The First Hospital of China Medical University, 155 Nanjing North Street, Heping District, Shenyang, 110001, Liaoning Province, People's Republic of China
| | - Mingjun Hao
- Center of Reproductive Medicine, Shengjing Hospital of China Medical University, Shenyang, 110004, China
| | - Cheng Cheng
- Department of Cardiology, The First Hospital of China Medical University, 155 Nanjing North Street, Heping District, Shenyang, 110001, Liaoning Province, People's Republic of China
| | - Mengke Liu
- Department of Cardiology, The First Hospital of China Medical University, 155 Nanjing North Street, Heping District, Shenyang, 110001, Liaoning Province, People's Republic of China
| | - Yuanhui Zhao
- Department of Cardiology, The First Hospital of China Medical University, 155 Nanjing North Street, Heping District, Shenyang, 110001, Liaoning Province, People's Republic of China
| | - Pengyu Jia
- Department of Cardiology, The First Hospital of China Medical University, 155 Nanjing North Street, Heping District, Shenyang, 110001, Liaoning Province, People's Republic of China
| | - Hongkun Jiang
- Department of Pediatrics, The First Hospital of China Medical University, 155 North Nanjing Street, Shenyang, 110001, China
| | - Da Li
- Center of Reproductive Medicine, Shengjing Hospital of China Medical University, Shenyang, 110004, China
- Key Laboratory of Reproductive and Genetic Medicine (China Medical University), National Health Commission, Shenyang, 110004, China
| | - Liu Cao
- Key Laboratory of Medical Cell Biology, Ministry of Education, 77 Puhe Road, Shenbei New District, Shenyang, 110001, Liaoning Province, People's Republic of China
- Institute of School of Basic Medicine, China Medical University, 77 Puhe Road, Shenbei New District, Shenyang, 110001, Liaoning Province, People's Republic of China
| | - Xingang Zhang
- Department of Cardiology, The First Hospital of China Medical University, 155 Nanjing North Street, Heping District, Shenyang, 110001, Liaoning Province, People's Republic of China.
| | - Ying Zhang
- Department of Cardiology, The First Hospital of China Medical University, 155 Nanjing North Street, Heping District, Shenyang, 110001, Liaoning Province, People's Republic of China.
- Institute of School of Basic Medicine, China Medical University, 77 Puhe Road, Shenbei New District, Shenyang, 110001, Liaoning Province, People's Republic of China.
| | - Yingxian Sun
- Department of Cardiology, The First Hospital of China Medical University, 155 Nanjing North Street, Heping District, Shenyang, 110001, Liaoning Province, People's Republic of China.
- Key Laboratory of Environmental Stress and Chronic Disease Control and Prevention, Ministry of Education, China Medical University, 77 Puhe Road, Shenbei New District, Shenyang, 110001, Liaoning Province, People's Republic of China.
| | - Naijin Zhang
- Department of Cardiology, The First Hospital of China Medical University, 155 Nanjing North Street, Heping District, Shenyang, 110001, Liaoning Province, People's Republic of China.
- Key Laboratory of Reproductive and Genetic Medicine (China Medical University), National Health Commission, Shenyang, 110004, China.
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Šrámek J, Němcová-Fürstová V, Kovář J. Molecular Mechanisms of Apoptosis Induction and Its Regulation by Fatty Acids in Pancreatic β-Cells. Int J Mol Sci 2021; 22:4285. [PMID: 33924206 PMCID: PMC8074590 DOI: 10.3390/ijms22084285] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 04/09/2021] [Accepted: 04/16/2021] [Indexed: 02/06/2023] Open
Abstract
Pancreatic β-cell failure and death contribute significantly to the pathogenesis of type 2 diabetes. One of the main factors responsible for β-cell dysfunction and subsequent cell death is chronic exposure to increased concentrations of FAs (fatty acids). The effect of FAs seems to depend particularly on the degree of their saturation. Saturated FAs induce apoptosis in pancreatic β-cells, whereas unsaturated FAs are well tolerated and are even capable of inhibiting the pro-apoptotic effect of saturated FAs. Molecular mechanisms of apoptosis induction by saturated FAs in β-cells are not completely elucidated. Saturated FAs induce ER stress, which in turn leads to activation of all ER stress pathways. When ER stress is severe or prolonged, apoptosis is induced. The main mediator seems to be the CHOP transcription factor. Via regulation of expression/activity of pro- and anti-apoptotic Bcl-2 family members, and potentially also through the increase in ROS production, CHOP switches on the mitochondrial pathway of apoptosis induction. ER stress signalling also possibly leads to autophagy signalling, which may activate caspase-8. Saturated FAs activate or inhibit various signalling pathways, i.e., p38 MAPK signalling, ERK signalling, ceramide signalling, Akt signalling and PKCδ signalling. This may lead to the activation of the mitochondrial pathway of apoptosis, as well. Particularly, the inhibition of the pro-survival Akt signalling seems to play an important role. This inhibition may be mediated by multiple pathways (e.g., ER stress signalling, PKCδ and ceramide) and could also consequence in autophagy signalling. Experimental evidence indicates the involvement of certain miRNAs in mechanisms of FA-induced β-cell apoptosis, as well. In the rather rare situations when unsaturated FAs are also shown to be pro-apoptotic, the mechanisms mediating this effect in β-cells seem to be the same as for saturated FAs. To conclude, FA-induced apoptosis rather appears to be preceded by complex cross talks of multiple signalling pathways. Some of these pathways may be regulated by decreased membrane fluidity due to saturated FA incorporation. Few data are available concerning molecular mechanisms mediating the protective effect of unsaturated FAs on the effect of saturated FAs. It seems that the main possible mechanism represents a rather inhibitory intervention into saturated FA-induced pro-apoptotic signalling than activation of some pro-survival signalling pathway(s) or metabolic interference in β-cells. This inhibitory intervention may be due to an increase of membrane fluidity.
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Affiliation(s)
- Jan Šrámek
- Department of Biochemistry, Cell and Molecular Biology & Center for Research of Diabetes, Metabolism and Nutrition, Third Faculty of Medicine, Charles University, Ruská 87, 100 00 Prague, Czech Republic;
| | - Vlasta Němcová-Fürstová
- Department of Biochemistry, Cell and Molecular Biology & Center for Research of Diabetes, Metabolism and Nutrition, Third Faculty of Medicine, Charles University, Ruská 87, 100 00 Prague, Czech Republic;
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Lipotoxic Impairment of Mitochondrial Function in β-Cells: A Review. Antioxidants (Basel) 2021; 10:antiox10020293. [PMID: 33672062 PMCID: PMC7919463 DOI: 10.3390/antiox10020293] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [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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Li Y, Lou W, Raja V, Denis S, Yu W, Schmidtke MW, Reynolds CA, Schlame M, Houtkooper RH, Greenberg ML. Cardiolipin-induced activation of pyruvate dehydrogenase links mitochondrial lipid biosynthesis to TCA cycle function. J Biol Chem 2019; 294:11568-11578. [PMID: 31186346 DOI: 10.1074/jbc.ra119.009037] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 05/22/2019] [Indexed: 12/17/2022] Open
Abstract
Cardiolipin (CL) is the signature phospholipid of mitochondrial membranes. Although it has long been known that CL plays an important role in mitochondrial bioenergetics, recent evidence in the yeast model indicates that CL is also essential for intermediary metabolism. To gain insight into the function of CL in energy metabolism in mammalian cells, here we analyzed the metabolic flux of [U-13C]glucose in a mouse C2C12 myoblast cell line, TAZ-KO, which is CL-deficient because of CRISPR/Cas9-mediated knockout of the CL-remodeling enzyme tafazzin (TAZ). TAZ-KO cells exhibited decreased flux of [U-13C]glucose to [13C]acetyl-CoA and M2 and M4 isotopomers of tricarboxylic acid (TCA) cycle intermediates. The activity of pyruvate carboxylase, the predominant enzyme for anaplerotic replenishing of the TCA cycle, was elevated in TAZ-KO cells, which also exhibited increased sensitivity to the pyruvate carboxylase inhibitor phenylacetate. We attributed a decreased carbon flux from glucose to acetyl-CoA in the TAZ-KO cells to a ∼50% decrease in pyruvate dehydrogenase (PDH) activity, which was observed in both TAZ-KO cells and cardiac tissue from TAZ-KO mice. Protein-lipid overlay experiments revealed that PDH binds to CL, and supplementing digitonin-solubilized TAZ-KO mitochondria with CL restored PDH activity to WT levels. Mitochondria from TAZ-KO cells exhibited an increase in phosphorylated PDH, levels of which were reduced in the presence of supplemented CL. These findings indicate that CL is required for optimal PDH activation, generation of acetyl-CoA, and TCA cycle function, findings that link the key mitochondrial lipid CL to TCA cycle function and energy metabolism.
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Affiliation(s)
- Yiran Li
- Department of Biological Sciences, Wayne State University, Detroit Michigan 48202
| | - Wenjia Lou
- Department of Biological Sciences, Wayne State University, Detroit Michigan 48202
| | - Vaishnavi Raja
- Department of Biological Sciences, Wayne State University, Detroit Michigan 48202
| | - Simone Denis
- Laboratory of Genetic Metabolic Diseases, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.,Amsterdam Gastroenterology and Metabolism, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.,Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Wenxi Yu
- Department of Biological Sciences, Wayne State University, Detroit Michigan 48202
| | - Michael W Schmidtke
- Department of Biological Sciences, Wayne State University, Detroit Michigan 48202
| | - Christian A Reynolds
- Department of Biological Sciences, Wayne State University, Detroit Michigan 48202
| | - Michael Schlame
- Department of Anesthesiology, New York University School of Medicine, New York 10016, New York.,Department of Cell Biology, New York University School of Medicine, New York 10016, New York
| | - Riekelt H Houtkooper
- Laboratory of Genetic Metabolic Diseases, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.,Amsterdam Gastroenterology and Metabolism, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.,Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Miriam L Greenberg
- Department of Biological Sciences, Wayne State University, Detroit Michigan 48202
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Pillai SS, Mini S. Attenuation of high glucose induced apoptotic and inflammatory signaling pathways in RIN-m5F pancreatic β cell lines by Hibiscus rosa sinensis L. petals and its phytoconstituents. JOURNAL OF ETHNOPHARMACOLOGY 2018; 227:8-17. [PMID: 30120944 DOI: 10.1016/j.jep.2018.08.022] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Revised: 07/25/2018] [Accepted: 08/14/2018] [Indexed: 06/08/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Hibiscus rosa sinensis petals possess wide range of pharmacological properties, with remarkable nutritional values. Diabetes is one of the most devastating diseases affecting the world today. A few side effects associated with the use of insulin and oral hypoglycemic agents prompted us to search new bioactive principles from antidiabetic plants used in traditional medicine. AIM OF THE STUDY The anti-diabetic therapeutic potential of the flavonoids rich ethyl acetate fraction of Hibiscus rosa sinensis petals (EHRS) was evaluated. MATERIALS AND METHODS High glucose (25 mM) induced apoptotic model of diabetes in RIN-m5F pancreatic β-cells was used for the study. RESULTS EHRS elevated the release of insulin in pancreatic cells and modulated apoptotic signaling cascades. It significantly reduced NF-κB nuclear translocation, thereby down-regulated the expressions of major inflammatory cytokines and up-regulated expressions of pancreatic β-cell functional genes such as, foxO-1, Ucn-3, Pdx-1, MafA and Nkx6.1. On comparison with its constituent phytochemicals, superior protective effect shown by EHRS may be due to the additive action of these phytoconstituents. CONCLUSIONS Results of the present study suggest hibiscus petals as a natural source and functional food of potential therapeutics to protect pancreatic β-cells in experimental diabetes mellitus.
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Affiliation(s)
- Sneha S Pillai
- Department of Biochemistry, University of Kerala, Thiruvananthapuram, Kerala 695581, India.
| | - S Mini
- Department of Biochemistry, University of Kerala, Thiruvananthapuram, Kerala 695581, India.
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Abstract
INTRODUCTION AND AIM Salidroside and curcumin (SC) formula could alleviate lipid deposition in high fat diet-induced nonalcoholic fatty liver disease (NAFLD). However, the mechanisms are still unknown, and the magnitude of potential therapeutic benefit remains understudied. MATERIAL AND METHODS The rats were treated with high fat diet for 14 weeks to induce NAFLD. The experiment was divided into control, model (NAFLD), SC formula and rosiglitazone groups (n = 7 in each group). Hematoxylin-eosin (H&E) staining was applied to detect liver morphological changes. Biochemical, metabolic indices and inflammation factors in liver tissue and serum were detected. Additionally, the activities of related enzymes were detected by enzyme-linked immunosorbent assay. RESULTS In the established rat model, typical lipid deposition and liver steatosis were observed. Liver triglyceride, free fatty acids, sera alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transferase, fasting insulin, fasting blood glucose and homeostasis model assessment of insulin resistance were elevated in model group. Liver malondialdehyde was significantly elevated, while superoxide dismutase was significantly decreased in model group, compared with control. Moreover, tumor necrosis factor-α and Interleukin-1 were significantly produced in model group, compared with control. As a mechanism, high fat diet decreased tissue AMP-activated protein kinase (AMPK), phosphorylated AMPK, carnitine palmitoyltransferase 1 and increased inacetyl-CoA carboxylase (ACCase), phosphorylated ACCase. Importantly, these abnormal changes caused by high fat diet were reduced by SC formula administration. CONCLUSION SC formula could ameliorate the injury caused by high fat diet. The effect was likely mediated via its influence on insulin resistance, lipid peroxidation injury and AMPK signaling pathway.
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Borck PC, Vettorazzi JF, Branco RCS, Batista TM, Santos-Silva JC, Nakanishi VY, Boschero AC, Ribeiro RA, Carneiro EM. Taurine supplementation induces long-term beneficial effects on glucose homeostasis in ob/ob mice. Amino Acids 2018; 50:765-774. [DOI: 10.1007/s00726-018-2553-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 03/11/2018] [Indexed: 10/17/2022]
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Sodium fluorocitrate having protective effect on palmitate-induced beta cell death improves hyperglycemia in diabetic db/db mice. Sci Rep 2017; 7:12916. [PMID: 29018279 PMCID: PMC5635019 DOI: 10.1038/s41598-017-13365-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 09/21/2017] [Indexed: 02/06/2023] Open
Abstract
Beta cell loss and insulin resistance play roles in the pathogenesis of type 2 diabetes. Elevated levels of free fatty acids in plasma might contribute to the loss of beta cells. The objective of this study was to find a chemical that could protect against palmitate-induced beta cell death and investigate whether such chemical could improve hyperglycemia in mouse model of type 2 diabetes. Sodium fluorocitrate (SFC), an aconitase inhibitor, was found to be strongly and specifically protective against palmitate-induced INS-1 beta cell death. However, the protective effect of SFC on palmitate-induced cell death was not likely to be due to its inhibitory activity for aconitase since inhibition or knockdown of aconitase failed to protect against palmitate-induced cell death. Since SFC inhibited the uptake of palmitate into INS-1 cells, reduced metabolism of fatty acids was thought to be involved in SFC’s protective effect. Ten weeks of treatment with SFC in db/db diabetic mice reduced glucose level but remarkably increased insulin level in the plasma. SFC improved impairment of glucose-stimulated insulin release and also reduced the loss of beta cells in db/db mice. Conclusively, SFC possessed protective effect against palmitate-induced lipotoxicity and improved hyperglycemia in mouse model of type 2 diabetes.
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Abstract
The pancreatic β-cell secretes insulin in response to elevated plasma glucose. This review applies an external bioenergetic critique to the central processes of glucose-stimulated insulin secretion, including glycolytic and mitochondrial metabolism, the cytosolic adenine nucleotide pool, and its interaction with plasma membrane ion channels. The control mechanisms responsible for the unique responsiveness of the cell to glucose availability are discussed from bioenergetic and metabolic control standpoints. The concept of coupling factor facilitation of secretion is critiqued, and an attempt is made to unravel the bioenergetic basis of the oscillatory mechanisms controlling secretion. The need to consider the physiological constraints operating in the intact cell is emphasized throughout. The aim is to provide a coherent pathway through an extensive, complex, and sometimes bewildering literature, particularly for those unfamiliar with the field.
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Affiliation(s)
- David G Nicholls
- Buck Institute for Research on Aging, Novato, California; and Department of Clinical Sciences, Unit of Molecular Metabolism, Lund University Diabetes Centre, Malmo, Sweden
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11
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Delgado-Goni T, Miniotis MF, Wantuch S, Parkes HG, Marais R, Workman P, Leach MO, Beloueche-Babari M. The BRAF Inhibitor Vemurafenib Activates Mitochondrial Metabolism and Inhibits Hyperpolarized Pyruvate-Lactate Exchange in BRAF-Mutant Human Melanoma Cells. Mol Cancer Ther 2016; 15:2987-2999. [PMID: 27765851 PMCID: PMC5136471 DOI: 10.1158/1535-7163.mct-16-0068] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 09/23/2016] [Accepted: 09/24/2016] [Indexed: 11/16/2022]
Abstract
Understanding the impact of BRAF signaling inhibition in human melanoma on key disease mechanisms is important for developing biomarkers of therapeutic response and combination strategies to improve long-term disease control. This work investigates the downstream metabolic consequences of BRAF inhibition with vemurafenib, the molecular and biochemical processes that underpin them, their significance for antineoplastic activity, and potential as noninvasive imaging response biomarkers. 1H NMR spectroscopy showed that vemurafenib decreases the glycolytic activity of BRAF-mutant (WM266.4 and SKMEL28) but not BRAFWT (CHL-1 and D04) human melanoma cells. In WM266.4 cells, this was associated with increased acetate, glycine, and myo-inositol levels and decreased fatty acyl signals, while the bioenergetic status was maintained. 13C NMR metabolic flux analysis of treated WM266.4 cells revealed inhibition of de novo lactate synthesis and glucose utilization, associated with increased oxidative and anaplerotic pyruvate carboxylase mitochondrial metabolism and decreased lipid synthesis. This metabolic shift was associated with depletion of hexokinase 2, acyl-CoA dehydrogenase 9, 3-phosphoglycerate dehydrogenase, and monocarboxylate transporters (MCT) 1 and 4 in BRAF-mutant but not BRAFWT cells and, interestingly, decreased BRAF-mutant cell dependency on glucose and glutamine for growth. Further, the reduction in MCT1 expression observed led to inhibition of hyperpolarized 13C-pyruvate-lactate exchange, a parameter that is translatable to in vivo imaging studies, in live WM266.4 cells. In conclusion, our data provide new insights into the molecular and metabolic consequences of BRAF inhibition in BRAF-driven human melanoma cells that may have potential for combinatorial therapeutic targeting as well as noninvasive imaging of response. Mol Cancer Ther; 15(12); 2987-99. ©2016 AACR.
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Affiliation(s)
- Teresa Delgado-Goni
- Cancer Research UK Cancer Imaging Centre, The Institute of Cancer Research, London, United Kingdom
| | - Maria Falck Miniotis
- Cancer Research UK Cancer Imaging Centre, The Institute of Cancer Research, London, United Kingdom
| | - Slawomir Wantuch
- Cancer Research UK Cancer Imaging Centre, The Institute of Cancer Research, London, United Kingdom
| | - Harold G Parkes
- Cancer Research UK Cancer Imaging Centre, The Institute of Cancer Research, London, United Kingdom
| | - Richard Marais
- Cancer Research UK Manchester Institute, Manchester, United Kingdom
| | - Paul Workman
- Cancer Research UK Cancer Therapeutics Unit, The Institute of Cancer Research, London, United Kingdom
| | - Martin O Leach
- Cancer Research UK Cancer Imaging Centre, The Institute of Cancer Research, London, United Kingdom.
| | - Mounia Beloueche-Babari
- Cancer Research UK Cancer Imaging Centre, The Institute of Cancer Research, London, United Kingdom.
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Kinase Signaling in Apoptosis Induced by Saturated Fatty Acids in Pancreatic β-Cells. Int J Mol Sci 2016; 17:ijms17091400. [PMID: 27626409 PMCID: PMC5037680 DOI: 10.3390/ijms17091400] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 08/18/2016] [Accepted: 08/22/2016] [Indexed: 12/12/2022] Open
Abstract
Pancreatic β-cell failure and death is considered to be one of the main factors responsible for type 2 diabetes. It is caused by, in addition to hyperglycemia, chronic exposure to increased concentrations of fatty acids, mainly saturated fatty acids. Molecular mechanisms of apoptosis induction by saturated fatty acids in β-cells are not completely clear. It has been proposed that kinase signaling could be involved, particularly, c-Jun N-terminal kinase (JNK), protein kinase C (PKC), p38 mitogen-activated protein kinase (p38 MAPK), extracellular signal-regulated kinase (ERK), and Akt kinases and their pathways. In this review, we discuss these kinases and their signaling pathways with respect to their possible role in apoptosis induction by saturated fatty acids in pancreatic β-cells.
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The MDM2-p53-pyruvate carboxylase signalling axis couples mitochondrial metabolism to glucose-stimulated insulin secretion in pancreatic β-cells. Nat Commun 2016; 7:11740. [PMID: 27265727 PMCID: PMC4897763 DOI: 10.1038/ncomms11740] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 04/26/2016] [Indexed: 02/06/2023] Open
Abstract
Mitochondrial metabolism is pivotal for glucose-stimulated insulin secretion (GSIS) in pancreatic β-cells. However, little is known about the molecular machinery that controls the homeostasis of intermediary metabolites in mitochondria. Here we show that the activation of p53 in β-cells, by genetic deletion or pharmacological inhibition of its negative regulator MDM2, impairs GSIS, leading to glucose intolerance in mice. Mechanistically, p53 activation represses the expression of the mitochondrial enzyme pyruvate carboxylase (PC), resulting in diminished production of the TCA cycle intermediates oxaloacetate and NADPH, and impaired oxygen consumption. The defective GSIS and mitochondrial metabolism in MDM2-null islets can be rescued by restoring PC expression. Under diabetogenic conditions, MDM2 and p53 are upregulated, whereas PC is reduced in mouse β-cells. Pharmacological inhibition of p53 alleviates defective GSIS in diabetic islets by restoring PC expression. Thus, the MDM2-p53-PC signalling axis links mitochondrial metabolism to insulin secretion and glucose homeostasis, and could represent a therapeutic target in diabetes.
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14
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Cao Z, Zhou Y, Zhu S, Feng J, Chen X, Liu S, Peng N, Yang X, Xu G, Zhu Y. Pyruvate Carboxylase Activates the RIG-I-like Receptor-Mediated Antiviral Immune Response by Targeting the MAVS signalosome. Sci Rep 2016; 6:22002. [PMID: 26906558 PMCID: PMC4764940 DOI: 10.1038/srep22002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 02/05/2016] [Indexed: 02/07/2023] Open
Abstract
When retinoic acid-inducible gene 1 protein (RIG-I)-like receptors sense viral dsRNA in the cytosol, RIG-I and melanoma differentiation-associated gene 5 (MDA5) are recruited to the mitochondria to interact with mitochondrial antiviral signaling protein (MAVS) and initiate antiviral immune responses. In this study, we demonstrate that the biotin-containing enzyme pyruvate carboxylase (PC) plays an essential role in the virus-triggered activation of nuclear factor kappa B (NF-κB) signaling mediated by MAVS. PC contributes to the enhanced production of type I interferons (IFNs) and pro-inflammatory cytokines, and PC knockdown inhibits the virus-triggered innate immune response. In addition, PC shows extensive antiviral activity against RNA viruses, including influenza A virus (IAV), human enterovirus 71 (EV71), and vesicular stomatitis virus (VSV). Furthermore, PC mediates antiviral action by targeting the MAVS signalosome and induces IFNs and pro-inflammatory cytokines by promoting phosphorylation of NF-κB inhibitor-α (IκBα) and the IκB kinase (IKK) complex, as well as NF-κB nuclear translocation, which leads to activation of interferon-stimulated genes (ISGs), including double-stranded RNA-dependent protein kinase (PKR) and myxovirus resistance protein 1 (Mx1). Our findings suggest that PC is an important player in host antiviral signaling.
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MESH Headings
- Adaptor Proteins, Signal Transducing/genetics
- Adaptor Proteins, Signal Transducing/immunology
- Animals
- Cell Line, Tumor
- Cytokines/genetics
- Cytokines/immunology
- DEAD Box Protein 58/genetics
- DEAD Box Protein 58/immunology
- Enterovirus A, Human/genetics
- Enterovirus A, Human/immunology
- Gene Expression Regulation
- Genes, Reporter
- HEK293 Cells
- Hepatocytes/immunology
- Hepatocytes/virology
- Humans
- Immunity, Innate
- Influenza A Virus, H3N2 Subtype/genetics
- Influenza A Virus, H3N2 Subtype/immunology
- Interferon Type I/genetics
- Interferon Type I/immunology
- Interferon-Induced Helicase, IFIH1/genetics
- Interferon-Induced Helicase, IFIH1/immunology
- Luciferases/genetics
- Luciferases/immunology
- NF-KappaB Inhibitor alpha/genetics
- NF-KappaB Inhibitor alpha/immunology
- NF-kappa B/genetics
- NF-kappa B/immunology
- Pyruvate Carboxylase/antagonists & inhibitors
- Pyruvate Carboxylase/genetics
- Pyruvate Carboxylase/immunology
- RNA, Small Interfering/genetics
- RNA, Small Interfering/immunology
- RNA, Viral/genetics
- RNA, Viral/immunology
- Receptors, Immunologic
- Signal Transduction
- Vesiculovirus/genetics
- Vesiculovirus/immunology
- eIF-2 Kinase/genetics
- eIF-2 Kinase/immunology
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Affiliation(s)
- Zhongying Cao
- State Key Laboratory of Virology and College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Yaqin Zhou
- State Key Laboratory of Virology and College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Shengli Zhu
- State Key Laboratory of Virology and College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Jian Feng
- State Key Laboratory of Virology and College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Xueyuan Chen
- State Key Laboratory of Virology and College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Shi Liu
- State Key Laboratory of Virology and College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Nanfang Peng
- State Key Laboratory of Virology and College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Xiaodan Yang
- State Key Laboratory of Virology and College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Gang Xu
- State Key Laboratory of Virology and College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Ying Zhu
- State Key Laboratory of Virology and College of Life Sciences, Wuhan University, Wuhan 430072, China
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15
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QiNan W, XiaGuang G, XiaoTian L, WuQuan D, Ling Z, Bing C. Par-4/NF-κB Mediates the Apoptosis of Islet β Cells Induced by Glucolipotoxicity. J Diabetes Res 2016; 2016:4692478. [PMID: 27340675 PMCID: PMC4906207 DOI: 10.1155/2016/4692478] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2016] [Accepted: 04/04/2016] [Indexed: 01/08/2023] Open
Abstract
Apoptosis of islet β cells is a primary pathogenic feature of type 2 diabetes, and ER stress and mitochondrial dysfunction play important roles in this process. Previous research has shown that prostate apoptosis response-4 (Par-4)/NF-κB induces cancer cell apoptosis through endoplasmic reticulum (ER) stress and mitochondrial dysfunction. However, the mechanism by which Par-4/NF-κB induces islet β cell apoptosis remains unknown. We used a high glucose/palmitate intervention to mimic type 2 diabetes in vitro. We demonstrated that the high glucose/palmitate intervention induced the expression and secretion of Par-4. It also causes increased expression and activation of NF-κB, which induced NIT-1 cell apoptosis and dysfunction. Overexpression of Par-4 potentiates these effects, whereas downregulation of Par-4 attenuates them. Inhibition of NF-κB inhibited the Par-4-induced apoptosis. Furthermore, these effects occurred through the ER stress cell membrane and mitochondrial pathway of apoptosis. Our findings reveal a novel role for Par-4/NF-κB in islet β cell apoptosis and type 2 diabetes.
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Affiliation(s)
- Wu QiNan
- Endocrine Department, The First Affiliated Hospital of the Third Military Medical University, Chong Qing 400038, China
| | - Gan XiaGuang
- Endocrine Department, The First Affiliated Hospital of the Third Military Medical University, Chong Qing 400038, China
| | - Lei XiaoTian
- Endocrine Department, The First Affiliated Hospital of the Third Military Medical University, Chong Qing 400038, China
| | - Deng WuQuan
- Endocrine Department, The First Affiliated Hospital of the Third Military Medical University, Chong Qing 400038, China
| | - Zhang Ling
- Outpatient Department, The First Affiliated Hospital of the Third Military Medical University, Chong Qing 400038, China
- *Zhang Ling: and
| | - Chen Bing
- Endocrine Department, The First Affiliated Hospital of the Third Military Medical University, Chong Qing 400038, China
- *Chen Bing:
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16
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Alshatwi AA, Subash-Babu P. Aloe-Emodin Protects RIN-5F (Pancreatic β-cell) Cell from Glucotoxicity via Regulation of Pro-Inflammatory Cytokine and Downregulation of Bax and Caspase 3. Biomol Ther (Seoul) 2016; 24:49-56. [PMID: 26759701 PMCID: PMC4703352 DOI: 10.4062/biomolther.2015.056] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 08/14/2015] [Accepted: 09/15/2015] [Indexed: 12/15/2022] Open
Abstract
To determine the protective effect of aloe-emodin (AE) from high glucose induced toxicity in RIN-5F (pancreatic β-cell) cell and restoration of its function was analyzed. RIN-5F cells have been cultured in high glucose (25 mM glucose) condition, with and without AE treatment. RIN-5F cells cultured in high glucose decreased cell viability and increased ROS levels after 48 hr compared with standard medium (5.5 mM glucose). Glucotoxicity was confirmed by significantly increased ROS production, increased pro-inflammatory (IFN-γ, IL-1β,) & decreased anti-inflammatory (IL-6&IL-10) cytokine levels, increased DNA fragmentation. In addition, we found increased Bax, caspase 3, Fadd, and Fas and significantly reduced Bcl-2 expression after 48 hr. RIN-5F treated with both high glucose and AE (20 μM) decreased ROS generation and prevent RIN-5F cell from glucotoxicity. In addition, AE treated cells cultured in high glucose were transferred to standard medium, normal responsiveness to glucose was restored within 8hr and normal basal insulin release within 24 hr was achieved when compared to high glucose.
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Affiliation(s)
- Ali A Alshatwi
- Adipogenesis and Immunobiology Research Lab, Department of Food Sciences and Nutrition, College of Food Sciences and Agriculture, King Saud University, Riyadh 11451, Kingdom of Saudi Arabia
| | - P Subash-Babu
- Adipogenesis and Immunobiology Research Lab, Department of Food Sciences and Nutrition, College of Food Sciences and Agriculture, King Saud University, Riyadh 11451, Kingdom of Saudi Arabia
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17
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Jung IR, Choi SE, Jung JG, Lee SA, Han SJ, Kim HJ, Kim DJ, Lee KW, Kang Y. Involvement of iron depletion in palmitate-induced lipotoxicity of beta cells. Mol Cell Endocrinol 2015; 407:74-84. [PMID: 25779532 DOI: 10.1016/j.mce.2015.03.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Revised: 01/28/2015] [Accepted: 03/10/2015] [Indexed: 12/28/2022]
Abstract
High levels of plasma free fatty acid are thought to contribute to the loss of pancreatic beta-cells in type 2 diabetes. In particular, saturated fatty acid such as palmitate or stearate can induce apoptosis in cultured beta cells (lipotoxicity). Endoplasmic reticulum stress is a critical mediator of free fatty acid-induced lipotoxicity. Recently, disorders in mitochondrial respiratory metabolism have been linked to lipotoxicity. Since iron is a critical component of respiratory metabolism, this study is initiated to determine whether abnormal iron metabolism is involved in palmitate-induced beta cell death. Immunoblotting analysis showed that treatment of INS-1 beta cells with palmitate reduced the level of transferrin receptor 1 (TfR1), but increased the level of heavy chain ferritin (FTH). In addition, palmitate reduced intracellular labile iron pool. Whereas iron depletion through treatment with iron-chelators deferoxamine or deferasirox augmented palmitate-induced cell death, iron supplementation with ferric chloride, ferrous sulfate, or holo-transferrin significantly protected cells against palmitate-induced death. Furthermore, overexpression of TfR1 reduced palmitate-induced cell death, whereas knockdown of TfR1 augmented cell death. In particular, treatment with deferoxamine increased the level of endoplasmic reticulum (ER) stress markers phospho-PERK, phospho-eIF2α, CHOP and phospho-c-Jun N-terminal kinase. Treatment with chemical chaperone significantly protected cells against deferoxamine-induced apoptosis. Iron supplementation also protected cells against palmitate-induced primary islet death. These data suggest that iron depletion plays an important role in palmitate-induced beta cell death through inducing ER stress. Therefore, attempts to block iron depletion might be able to prevent beta cell loss in type 2 diabetes.
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Affiliation(s)
- Ik-Rak Jung
- Department of Physiology, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea; Department of Biomedical Science, The Graduate School, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea
| | - Sung-E Choi
- Department of Physiology, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea
| | - Jong-Gab Jung
- Department of Biomedical Science, The Graduate School, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea; Department of Endocrinology and Metabolism, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea
| | - Sang-A Lee
- Department of Endocrinology and Metabolism, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea
| | - Seung Jin Han
- Department of Endocrinology and Metabolism, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea
| | - Hae Jin Kim
- Department of Endocrinology and Metabolism, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea
| | - Dae Jung Kim
- Department of Endocrinology and Metabolism, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea
| | - Kwan-Woo Lee
- Department of Endocrinology and Metabolism, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea
| | - Yup Kang
- Department of Physiology, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea; Department of Biomedical Science, The Graduate School, Ajou University School of Medicine, Suwon, Kyunggi-do 442-749, Republic of Korea.
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18
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Wang C, Zou S, Cui Z, Guo P, Meng Q, Shi X, Gao Y, Yang G, Han Z. Zerumbone protects INS-1 rat pancreatic beta cells from high glucose-induced apoptosis through generation of reactive oxygen species. Biochem Biophys Res Commun 2015; 460:205-9. [DOI: 10.1016/j.bbrc.2015.03.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 03/03/2015] [Indexed: 02/08/2023]
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