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Gelbach PE, Zheng D, Fraser SE, White KL, Graham NA, Finley SD. Kinetic and data-driven modeling of pancreatic β-cell central carbon metabolism and insulin secretion. PLoS Comput Biol 2022; 18:e1010555. [PMID: 36251711 PMCID: PMC9612825 DOI: 10.1371/journal.pcbi.1010555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 10/27/2022] [Accepted: 09/08/2022] [Indexed: 11/06/2022] Open
Abstract
Pancreatic β-cells respond to increased extracellular glucose levels by initiating a metabolic shift. That change in metabolism is part of the process of glucose-stimulated insulin secretion and is of particular interest in the context of diabetes. However, we do not fully understand how the coordinated changes in metabolic pathways and metabolite products influence insulin secretion. In this work, we apply systems biology approaches to develop a detailed kinetic model of the intracellular central carbon metabolic pathways in pancreatic β-cells upon stimulation with high levels of glucose. The model is calibrated to published metabolomics datasets for the INS1 823/13 cell line, accurately capturing the measured metabolite fold-changes. We first employed the calibrated mechanistic model to estimate the stimulated cell's fluxome. We then used the predicted network fluxes in a data-driven approach to build a partial least squares regression model. By developing the combined kinetic and data-driven modeling framework, we gain insights into the link between β-cell metabolism and glucose-stimulated insulin secretion. The combined modeling framework was used to predict the effects of common anti-diabetic pharmacological interventions on metabolite levels, flux through the metabolic network, and insulin secretion. Our simulations reveal targets that can be modulated to enhance insulin secretion. The model is a promising tool to contextualize and extend the usefulness of metabolomics data and to predict dynamics and metabolite levels that are difficult to measure in vitro. In addition, the modeling framework can be applied to identify, explain, and assess novel and clinically-relevant interventions that may be particularly valuable in diabetes treatment.
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Affiliation(s)
- Patrick E. Gelbach
- Department of Biomedical Engineering, USC, Los Angeles, California, United States of America
| | - Dongqing Zheng
- Mork Family Department of Chemical Engineering and Materials Science, USC, Los Angeles, California, United States of America
| | - Scott E. Fraser
- Translational Imaging Center, University of Southern California, Los Angeles, California, United States of America
| | - Kate L. White
- Departments of Biological Sciences and Chemistry, Bridge Institute, USC Michelson Center, USC, Los Angeles, California, United States of America
| | - Nicholas A. Graham
- Mork Family Department of Chemical Engineering and Materials Science, USC, Los Angeles, California, United States of America
| | - Stacey D. Finley
- Department of Biomedical Engineering, USC, Los Angeles, California, United States of America
- Mork Family Department of Chemical Engineering and Materials Science, USC, Los Angeles, California, United States of America
- Department of Quantitative and Computational Biology, USC, Los Angeles, California, United States of America
- * E-mail:
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2
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Zhai J, Zhu Y, Wu Y, Li N, Cao Y, Guo Y, Xu L. Antioxidant Effect of Tyr-Ala Extracted from Zein on INS-1 Cells and Type 2 Diabetes High-Fat-Diet-Induced Mice. Antioxidants (Basel) 2022; 11:antiox11061111. [PMID: 35740008 PMCID: PMC9219942 DOI: 10.3390/antiox11061111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 05/23/2022] [Accepted: 05/29/2022] [Indexed: 11/16/2022] Open
Abstract
Type 2 diabetes mellitus (T2DM) is associated with an oxidative milieu that often leads to adverse health problems. Bioactive peptides of zein possess outstanding antioxidant activity; however, their effects on hyperglycemia-related oxidative stress remain elusive. In the present study, the dipeptide Tyr-Ala (YA), a functional peptide with typical health benefits, was applied to alleviate oxidative stress in pancreatic islets under hyperglycemic conditions. By detecting viability, antioxidant ability, and insulin secretion in INS-1 cells, YA showed excellent protection of INS-1 cells from H2O2 oxidative stress, erasing reactive oxygen species (ROS) and promoting insulin secretion. Moreover, by Western blotting, we found that YA can regulate the PI3K/Akt signaling pathway associated with glycometabolism. After establishing a T2DM mice model, we treated mice with YA and measured glucose, insulin, hemoglobin A1C (HbA1c), total cholesterol (TC), triglyceride (TG), and malonaldehyde (MDA) levels and activities of superoxide dismutase (SOD) and glutathione (GSH) from blood samples. We observed that YA could reduce the production of glucose, insulin, HbA1c, TC, TG, and MDA, in addition to enhancing the activities of SOD and GSH. YA could also repair the function of the kidneys and pancreas of T2DM mice. Along with the decline in fasting blood glucose, the oxidative stress in islets was alleviated in T2DM mice after YA administration. This may improve the health situation of diabetic patients in the future.
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Affiliation(s)
- Jinghui Zhai
- Key Laboratory for Molecular Enzymology and Engineering, The Ministry of Education, National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun 130012, China; (J.Z.); (Y.Z.); (N.L.); (Y.C.)
- Department of Pharmacy, First Hospital of Jilin University, Changchun 130021, China
| | - Yuhua Zhu
- Key Laboratory for Molecular Enzymology and Engineering, The Ministry of Education, National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun 130012, China; (J.Z.); (Y.Z.); (N.L.); (Y.C.)
| | - Yi Wu
- College of Pharmacy, Jilin University, Changchun 130033, China;
| | - Na Li
- Key Laboratory for Molecular Enzymology and Engineering, The Ministry of Education, National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun 130012, China; (J.Z.); (Y.Z.); (N.L.); (Y.C.)
| | - Yue Cao
- Key Laboratory for Molecular Enzymology and Engineering, The Ministry of Education, National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun 130012, China; (J.Z.); (Y.Z.); (N.L.); (Y.C.)
| | - Yi Guo
- Key Laboratory for Molecular Enzymology and Engineering, The Ministry of Education, National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun 130012, China; (J.Z.); (Y.Z.); (N.L.); (Y.C.)
- Correspondence: (Y.G.); (L.X.)
| | - Li Xu
- Key Laboratory for Molecular Enzymology and Engineering, The Ministry of Education, National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun 130012, China; (J.Z.); (Y.Z.); (N.L.); (Y.C.)
- Correspondence: (Y.G.); (L.X.)
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Plecitá-Hlavatá L, Engstová H, Holendová B, Tauber J, Špaček T, Petrásková L, Křen V, Špačková J, Gotvaldová K, Ježek J, Dlasková A, Smolková K, Ježek P. Mitochondrial Superoxide Production Decreases on Glucose-Stimulated Insulin Secretion in Pancreatic β Cells Due to Decreasing Mitochondrial Matrix NADH/NAD + Ratio. Antioxid Redox Signal 2020; 33:789-815. [PMID: 32517485 PMCID: PMC7482716 DOI: 10.1089/ars.2019.7800] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 06/03/2020] [Accepted: 06/08/2020] [Indexed: 12/19/2022]
Abstract
Aims: Glucose-stimulated insulin secretion (GSIS) in pancreatic β cells was expected to enhance mitochondrial superoxide formation. Hence, we elucidated relevant redox equilibria. Results: Unexpectedly, INS-1E cells at transitions from 3 (11 mM; pancreatic islets from 5 mM) to 25 mM glucose decreased matrix superoxide release rates (MitoSOX Red monitoring validated by MitoB) and H2O2 (mitoHyPer, subtracting mitoSypHer emission). Novel double-channel fluorescence lifetime imaging, approximating free mitochondrial matrix NADHF, indicated its ∼20% decrease. Matrix NAD+F increased on GSIS, indicated by the FAD-emission lifetime decrease, reflecting higher quenching of FAD by NAD+F. The participation of pyruvate/malate and pyruvate/citrate redox shuttles, elevating cytosolic NADPHF (iNAP1 fluorescence monitoring) at the expense of matrix NADHF, was indicated, using citrate (2-oxoglutarate) carrier inhibitors and cytosolic malic enzyme silencing: All changes vanished on these manipulations. 13C-incorporation from 13C-L-glutamine into 13C-citrate reflected the pyruvate/isocitrate shuttle. Matrix NADPHF (iNAP3 monitored) decreased. With decreasing glucose, the suppressor of Complex III site Q electron leak (S3QEL) suppressor caused a higher Complex I IF site contribution, but a lower superoxide fraction ascribed to the Complex III site IIIQo. Thus, the diminished matrix NADHF/NAD+F decreased Complex I flavin site IF superoxide formation on GSIS. Innovation: Mutually validated methods showed decreasing superoxide release into the mitochondrial matrix in pancreatic β cells on GSIS, due to the decreasing matrix NADHF/NAD+F (NADPHF/NADP+F) at increasing cytosolic NADPHF levels. The developed innovative methods enable real-time NADH/NAD+ and NADPH/NADP+ monitoring in any distinct cell compartment. Conclusion: The export of reducing equivalents from mitochondria adjusts lower mitochondrial superoxide production on GSIS, but it does not prevent oxidative stress in pancreatic β cells.
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Affiliation(s)
- Lydie Plecitá-Hlavatá
- Department of Mitochondrial Physiology, No. 75, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Hana Engstová
- Department of Mitochondrial Physiology, No. 75, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Blanka Holendová
- Department of Mitochondrial Physiology, No. 75, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Jan Tauber
- Department of Mitochondrial Physiology, No. 75, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Tomáš Špaček
- Department of Mitochondrial Physiology, No. 75, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Lucie Petrásková
- Laboratory of Biotransformation, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Vladimír Křen
- Laboratory of Biotransformation, Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Jitka Špačková
- Department of Mitochondrial Physiology, No. 75, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Klára Gotvaldová
- Department of Mitochondrial Physiology, No. 75, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Jan Ježek
- Department of Mitochondrial Physiology, No. 75, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
- The Gurdon Institute, University of Cambridge, Cambridge, United Kingdom
| | - Andrea Dlasková
- Department of Mitochondrial Physiology, No. 75, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Katarína Smolková
- Department of Mitochondrial Physiology, No. 75, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Petr Ježek
- Department of Mitochondrial Physiology, No. 75, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
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The Molecular Mechanisms by Which Vitamin D Prevents Insulin Resistance and Associated Disorders. Int J Mol Sci 2020; 21:ijms21186644. [PMID: 32932777 PMCID: PMC7554927 DOI: 10.3390/ijms21186644] [Citation(s) in RCA: 80] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Revised: 09/07/2020] [Accepted: 09/09/2020] [Indexed: 02/06/2023] Open
Abstract
Numerous studies have shown that vitamin D deficiency is very common in modern societies and is perceived as an important risk factor in the development of insulin resistance and related diseases such as obesity and type 2 diabetes (T2DM). While it is generally accepted that vitamin D is a regulator of bone homeostasis, its ability to counteract insulin resistance is subject to debate. The goal of this communication is to review the molecular mechanism by which vitamin D reduces insulin resistance and related complications. The university library, PUBMED, and Google Scholar were searched to find relevant studies to be summarized in this review article. Insulin resistance is accompanied by chronic hyperglycaemia and inflammation. Recent studies have shown that vitamin D exhibits indirect antioxidative properties and participates in the maintenance of normal resting ROS level. Appealingly, vitamin D reduces inflammation and regulates Ca2+ level in many cell types. Therefore, the beneficial actions of vitamin D include diminished insulin resistance which is observed as an improvement of glucose and lipid metabolism in insulin-sensitive tissues.
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Abstract
Glucose-induced (physiological) insulin secretion from the islet β-cell involves interplay between cationic (i.e., changes in intracellular calcium) and metabolic (i.e., generation of hydrophobic and hydrophilic second messengers) events. A large body of evidence affirms support for novel regulation, by G proteins, of specific intracellular signaling events, including actin cytoskeletal remodeling, transport of insulin-containing granules to the plasma membrane for fusion, and secretion of insulin into the circulation. This article highlights the following aspects of GPCR-G protein biology of the islet. First, it overviews our current understanding of the identity of a wide variety of G protein regulators and their modulatory roles in GPCR-G protein-effector coupling, which is requisite for optimal β-cell function under physiological conditions. Second, it describes evidence in support of novel, noncanonical, GPCR-independent mechanisms of activation of G proteins in the islet. Third, it highlights the evidence indicating that abnormalities in G protein function lead to islet β-cell dysregulation and demise under the duress of metabolic stress and diabetes. Fourth, it summarizes observations of potential beneficial effects of GPCR agonists in preventing/halting metabolic defects in the islet β-cell under various pathological conditions (e.g., metabolic stress and inflammation). Lastly, it identifies knowledge gaps and potential avenues for future research in this evolving field of translational islet biology. Published 2020. Compr Physiol 10:453-490, 2020.
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Affiliation(s)
- Anjaneyulu Kowluru
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Center for Translational Research in Diabetes, Biomedical Research Service, John D. Dingell VA Medical Center, Wayne State University, Detroit, Michigan, USA
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The molecular mechanisms by which vitamin D improve glucose homeostasis: A mechanistic review. Life Sci 2020; 244:117305. [DOI: 10.1016/j.lfs.2020.117305] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Accepted: 01/12/2020] [Indexed: 12/16/2022]
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Kahancová A, Sklenář F, Ježek P, Dlasková A. Overexpression of native IF1 downregulates glucose-stimulated insulin secretion by pancreatic INS-1E cells. Sci Rep 2020; 10:1551. [PMID: 32005857 PMCID: PMC6994519 DOI: 10.1038/s41598-020-58411-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 01/15/2020] [Indexed: 01/08/2023] Open
Abstract
We have previously reported that transient knock-down of ATPase inhibitory factor 1 (IF1) by siRNA upregulates ATP levels and subsequently augments insulin secretion in model pancreatic β-cells INS-1E. Here we investigated how long-term IF1-overexpression impacts pancreatic β-cell bioenergetics and insulin secretion. We generated INS-1E cell line stably overexpressing native IF1. We revealed that IF1 overexpression leads to a substantial decrease in ATP levels and reduced glucose-stimulated insulin secretion. A decrease in total cellular ATP content was also reflected in decreased free ATP cytosolic and mitochondrial levels, as monitored with ATeam biosensor. Consistently, cellular respiration of IF1-overexpressing cells was decreased. 3D structured illumination microscopy (SIM) revealed a higher amount of insulin granules with higher volume in IF1-overexpressing cells. Similar effects occurred when cells were incubated at low glucose concentrations. Noteworthy, activation of PKA by dibutyryl cAMP entirely abolished the inhibitory effect of IF1 overexpression on ATP production and insulin secretion. Mitochondrial network morphology and cristae ultrastructure in INS-1E overexpressing IF1 remained mostly unchanged. Finally, we show that INS-1E cells decrease their IF1 protein levels relative to ATP synthase α-subunit in response to increased glucose. In conclusion, IF1 actively downregulates INS-1E cellular metabolism and reduces their ability to secrete insulin.
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Affiliation(s)
- Anežka Kahancová
- Department of Mitochondrial Physiology, No. 75, Institute of Physiology, The Czech Academy of Sciences, Prague, Czech Republic
| | - Filip Sklenář
- Department of Mitochondrial Physiology, No. 75, Institute of Physiology, The Czech Academy of Sciences, Prague, Czech Republic
| | - Petr Ježek
- Department of Mitochondrial Physiology, No. 75, Institute of Physiology, The Czech Academy of Sciences, Prague, Czech Republic
| | - Andrea Dlasková
- Department of Mitochondrial Physiology, No. 75, Institute of Physiology, The Czech Academy of Sciences, Prague, Czech Republic.
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Zhu Y, Ren C, Zhang M, Zhong Y. Perilipin 5 Reduces Oxidative Damage Associated With Lipotoxicity by Activating the PI3K/ERK-Mediated Nrf2-ARE Signaling Pathway in INS-1 Pancreatic β-Cells. Front Endocrinol (Lausanne) 2020; 11:166. [PMID: 32296390 PMCID: PMC7136399 DOI: 10.3389/fendo.2020.00166] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 03/09/2020] [Indexed: 12/16/2022] Open
Abstract
Oxidative stress induced by free fatty acid overload in pancreatic β-cells is a potential contributory factor to dysfunction of insulin secretion and apoptotic cell death. Perilipin 5 (Plin5) has been reported to ameliorate oxidative stress-mediated damage in non-insulin-secreting tissues. We tested the hypothesis that Plin5 plays a similar role in pancreatic β-cells, which are extremely sensitive to oxidative stress. Here, our in vitro data showed that Plin5-mediated alleviation of palmitate-triggered apoptosis involves the mitochondrial pathway. And the protective role of Plin5 on β-cells was partially dependent on its modulation in oxidative stress. Upregulation of Plin5 in INS-1 cells decreased reactive oxygen species production, enhanced cellular glutathione levels, and induced expression of antioxidant enzymes glutamate-cysteine ligase catalytic subunit and heme oxygenase-1. However, knocking out of Plin5 abolished all of these beneficial effects. Furthermore, by using the O2- scavenger MnTMPyP, we verified that altering Plin5 expression impacted lipotoxic cell death partially via modulating oxidative stress. Mechanistic experiments revealed that Plin5 induced Nrf2-ARE system, a master regulator in the cellular adaptive response to oxidative stress, by activating PI3K/Akt and ERK signal pathways, contributing to the increase of antioxidant defense and consequently improving β-cell function and survival in the presence of lipotoxic oxidative stress. Overall, our findings indicate that Plin5 abrogates oxidative damage in INS-1 β-cells during lipotoxic stress partially through the enhancement of antioxidant defense involving the PI3K/Akt and ERK mediated Nrf2-ARE system.
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Affiliation(s)
- Yunxia Zhu
- Department of Geriatrics, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
- *Correspondence: Yunxia Zhu
| | - Chenxi Ren
- Department of Geriatrics, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - Mingliang Zhang
- Department of Endocrinology and Metabolism, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - Yuan Zhong
- Department of Geriatrics, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
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Nrf2 Activation Protects Mouse Beta Cells from Glucolipotoxicity by Restoring Mitochondrial Function and Physiological Redox Balance. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2019; 2019:7518510. [PMID: 31827698 PMCID: PMC6885177 DOI: 10.1155/2019/7518510] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 07/31/2019] [Accepted: 09/06/2019] [Indexed: 12/25/2022]
Abstract
Influencing the redox balance of pancreatic beta cells could be a promising strategy for the treatment of diabetes. Nuclear factor erythroid 2p45-related factor 2 (Nrf2) is present in beta cells and regulates numerous genes involved in antioxidant defense. As reactive oxygen species (ROS) are important for beta cell signaling but induce oxidative stress when present in excess, this study elucidates the influence of Nrf2-activating compounds on different kinds of ROS and correlates changes in redox balance to effects on mitochondrial function, insulin release, and cell viability. Acute glucose stimulation (15 mmol/L) of murine islet cells of C57Bl/6N mice affects ROS and redox status of the cells differently. Those ROS monitored by dihydroethidium, which detects superoxide radical anions, decrease. By contrast, oxidant status, monitored by dichlorodihydrofluorescein, as well as intracellular H2O2, increases. Glucolipotoxicity completely prevents these fast, glucose-mediated alterations and inhibits glucose-induced NAD(P)H production, mitochondrial hyperpolarization, and ATP synthesis. Oltipraz (10 μmol/L) or dimethyl fumarate (DMF, 50 μmol/L) leads to nuclear accumulation of Nrf2, restores mitochondrial activity and glucose-dependent ROS turnover, and antagonizes glucolipotoxicity-induced inhibition of insulin release and apoptosis. Importantly, these beneficial effects only occur when beta cells are challenged and damaged by high lipid and carbohydrate supply. At physiological conditions, insulin release is markedly reduced in response to both Nrf2 activators. This is not associated with severe impairment of glucose-induced mitochondrial hyperpolarization or a rise in apoptosis but coincides with altered ROS handling. In conclusion, Nrf2 activators protect beta cells against glucolipotoxicity by preserving mitochondrial function and redox balance. As our data show that this maintains glucose-stimulated insulin secretion, targeting Nrf2 might be suited to ameliorate progression of type 2 diabetes mellitus. By contrast, nonstressed beta cells do not benefit from Nrf2 activation, thus underlining the importance of physiological shifts in ROS homeostasis for the regulation of beta cell function.
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Heikkilä E, Hermant A, Thevenet J, Bermont F, Kulkarni SS, Ratajczak J, Santo-Domingo J, Dioum EH, Canto C, Barron D, Wiederkehr A, De Marchi U. The plant product quinic acid activates Ca 2+ -dependent mitochondrial function and promotes insulin secretion from pancreatic beta cells. Br J Pharmacol 2019; 176:3250-3263. [PMID: 31166006 DOI: 10.1111/bph.14757] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 04/07/2019] [Accepted: 05/04/2019] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND AND PURPOSE Quinic acid (QA) is an abundant natural compound from plant sources which may improve metabolic health. However, little attention has been paid to its effects on pancreatic beta-cell functions, which contribute to the control of metabolic health by lowering blood glucose. Strategies targeting beta-cell signal transduction are a new approach for diabetes treatment. This study investigated the efficacy of QA to stimulate beta-cell function by targeting the basic molecular machinery of metabolism-secretion coupling. EXPERIMENTAL APPROACH We measured bioenergetic parameters and insulin exocytosis in a model of insulin-secreting beta-cells (INS-1E), together with Ca2+ homeostasis, using genetically encoded sensors, targeted to different subcellular compartments. Islets from mice chronically infused with QA were also assessed. KEY RESULTS QA triggered transient cytosolic Ca2+ increases in insulin-secreting cells by mobilizing Ca2+ from intracellular stores, such as endoplasmic reticulum. Following glucose stimulation, QA increased glucose-induced mitochondrial Ca2+ transients. We also observed a QA-induced rise of the NAD(P)H/NAD(P)+ ratio, augmented ATP synthase-dependent respiration, and enhanced glucose-stimulated insulin secretion. QA promoted beta-cell function in vivo as islets from mice infused with QA displayed improved glucose-induced insulin secretion. A diet containing QA improved glucose tolerance in mice. CONCLUSIONS AND IMPLICATIONS QA modulated intracellular Ca2+ homeostasis, enhancing glucose-stimulated insulin secretion in both INS-1E cells and mouse islets. By increasing mitochondrial Ca2+ , QA activated the coordinated stimulation of oxidative metabolism, mitochondrial ATP synthase-dependent respiration, and therefore insulin secretion. Bioactive agents raising mitochondrial Ca2+ in pancreatic beta-cells could be used to treat diabetes.
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Affiliation(s)
- Eija Heikkilä
- Nestlé Research, EPFL Innovation Park, Lausanne, Switzerland
| | - Aurelie Hermant
- Nestlé Research, EPFL Innovation Park, Lausanne, Switzerland
| | | | - Flavien Bermont
- Nestlé Research, EPFL Innovation Park, Lausanne, Switzerland
| | | | | | | | - El Hadji Dioum
- Nestlé Research, EPFL Innovation Park, Lausanne, Switzerland
| | - Carles Canto
- Nestlé Research, EPFL Innovation Park, Lausanne, Switzerland
| | - Denis Barron
- Nestlé Research, EPFL Innovation Park, Lausanne, Switzerland
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Nemecz M, Constantin A, Dumitrescu M, Alexandru N, Filippi A, Tanko G, Georgescu A. The Distinct Effects of Palmitic and Oleic Acid on Pancreatic Beta Cell Function: The Elucidation of Associated Mechanisms and Effector Molecules. Front Pharmacol 2019; 9:1554. [PMID: 30719005 PMCID: PMC6348268 DOI: 10.3389/fphar.2018.01554] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 12/20/2018] [Indexed: 12/13/2022] Open
Abstract
In this study, we aimed to identify the mechanisms underlying the different effects of palmitic acid and oleic acid on human pancreatic beta cell function. To address this problem, the oxidative stress, endoplasmic reticulum stress, inflammation, apoptosis and their mediator molecules have been investigated in the insulin releasing beta cells exposed to palmitic and/or oleic acid. Herein, we have demonstrated that in cultured 1.1B4 beta cells oleic acid promotes neutral lipid accumulation and insulin secretion, whereas palmitic acid is poorly incorporated into triglyceride and it does not stimulate insulin secretion from human pancreatic islets at physiologically glucose concentrations. In addition, palmitic acid caused: (1) oxidative stress through a mechanism involving increases in ROS production and MMP-2 protein expression/gelatinolytic activity associated with down-regulation of SOD2 protein; (2) endoplasmic reticulum stress by up-regulation of chaperone BiP protein and unfolded protein response (UPR) transcription factors (eIF2α, ATF6, XBP1u proteins) and by PTP-1B down-regulation in both mRNA and protein levels; (3) inflammation through enhanced synthesis of proinflammatory cytokines (IL6, IL8 proteins); and (4) apoptosis by enforced proteic expression of CHOP multifunctional transcription factor. Oleic acid alone had opposite effects due to its different capacity of controlling these metabolic pathways, in particular by reduction of the ROS levels and MMP-2 activity, down-regulation of BiP, eIF2α, ATF6, XBP1u, CHOP, IL6, IL8 and by SOD2 and PTP-1B overexpression. The supplementation of saturated palmitic acid with the monounsaturated oleic acid reversed the negative effects of palmitic acid alone regulating insulin secretion from pancreatic beta cells through ROS, MMP-2, ATF6, XBP1u, IL8 reduction and SOD2, PTP-1B activation. Our findings have shown the protective action of oleic acid against palmitic acid on beta cell lipotoxicity through promotion of triglyceride accumulation and insulin secretion and regulation of some effector molecules involved in oxidative stress, endoplasmic reticulum stress, inflammation and apoptosis.
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Affiliation(s)
- Miruna Nemecz
- Department of Pathophysiology and Pharmacology, Institute of Cellular Biology and Pathology 'Nicolae Simionescu' of Romanian Academy, Bucharest, Romania
| | - Alina Constantin
- Department of Pathophysiology and Pharmacology, Institute of Cellular Biology and Pathology 'Nicolae Simionescu' of Romanian Academy, Bucharest, Romania
| | - Madalina Dumitrescu
- Department of Pathophysiology and Pharmacology, Institute of Cellular Biology and Pathology 'Nicolae Simionescu' of Romanian Academy, Bucharest, Romania
| | - Nicoleta Alexandru
- Department of Pathophysiology and Pharmacology, Institute of Cellular Biology and Pathology 'Nicolae Simionescu' of Romanian Academy, Bucharest, Romania
| | - Alexandru Filippi
- Department of Pathophysiology and Pharmacology, Institute of Cellular Biology and Pathology 'Nicolae Simionescu' of Romanian Academy, Bucharest, Romania
| | - Gabriela Tanko
- Department of Pathophysiology and Pharmacology, Institute of Cellular Biology and Pathology 'Nicolae Simionescu' of Romanian Academy, Bucharest, Romania
| | - Adriana Georgescu
- Department of Pathophysiology and Pharmacology, Institute of Cellular Biology and Pathology 'Nicolae Simionescu' of Romanian Academy, Bucharest, Romania
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12
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Ježek P, Holendová B, Garlid KD, Jabůrek M. Mitochondrial Uncoupling Proteins: Subtle Regulators of Cellular Redox Signaling. Antioxid Redox Signal 2018; 29:667-714. [PMID: 29351723 PMCID: PMC6071544 DOI: 10.1089/ars.2017.7225] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
SIGNIFICANCE Mitochondria are the energetic, metabolic, redox, and information signaling centers of the cell. Substrate pressure, mitochondrial network dynamics, and cristae morphology state are integrated by the protonmotive force Δp or its potential component, ΔΨ, which are attenuated by proton backflux into the matrix, termed uncoupling. The mitochondrial uncoupling proteins (UCP1-5) play an eminent role in the regulation of each of the mentioned aspects, being involved in numerous physiological events including redox signaling. Recent Advances: UCP2 structure, including purine nucleotide and fatty acid (FA) binding sites, strongly support the FA cycling mechanism: UCP2 expels FA anions, whereas uncoupling is achieved by the membrane backflux of protonated FA. Nascent FAs, cleaved by phospholipases, are preferential. The resulting Δp dissipation decreases superoxide formation dependent on Δp. UCP-mediated antioxidant protection and its impairment are expected to play a major role in cell physiology and pathology. Moreover, UCP2-mediated aspartate, oxaloacetate, and malate antiport with phosphate is expected to alter metabolism of cancer cells. CRITICAL ISSUES A wide range of UCP antioxidant effects and participations in redox signaling have been reported; however, mechanisms of UCP activation are still debated. Switching off/on the UCP2 protonophoretic function might serve as redox signaling either by employing/releasing the extra capacity of cell antioxidant systems or by directly increasing/decreasing mitochondrial superoxide sources. Rapid UCP2 degradation, FA levels, elevation of purine nucleotides, decreased Mg2+, or increased pyruvate accumulation may initiate UCP-mediated redox signaling. FUTURE DIRECTIONS Issues such as UCP2 participation in glucose sensing, neuronal (synaptic) function, and immune cell activation should be elucidated. Antioxid. Redox Signal. 29, 667-714.
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Affiliation(s)
- Petr Ježek
- 1 Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences , Prague, Czech Republic
| | - Blanka Holendová
- 1 Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences , Prague, Czech Republic
| | - Keith D Garlid
- 2 UCLA Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA , Los Angeles, California
| | - Martin Jabůrek
- 1 Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences , Prague, Czech Republic
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Kahancová A, Sklenář F, Ježek P, Dlasková A. Regulation of glucose-stimulated insulin secretion by ATPase Inhibitory Factor 1 (IF1). FEBS Lett 2018; 592:999-1009. [PMID: 29380352 DOI: 10.1002/1873-3468.12991] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 01/16/2018] [Accepted: 01/22/2018] [Indexed: 12/13/2022]
Abstract
ATPase Inhibitory factor 1 (IF1) is an endogenous regulator of mitochondrial ATP synthase, which is involved in cellular metabolism. Although great progress has been made, biological roles of IF1 and molecular mechanisms of its action are still to be elucidated. Here, we show that IF1 is present in pancreatic β-cells, bound to the ATP synthase also under normal physiological conditions. IF1 silencing in model pancreatic β-cells (INS-1E) increases insulin secretion over a range of glucose concentrations. The left-shifted dose-response curve reveals excessive insulin secretion even under low glucose, corresponding to fasting conditions. A parallel increase in cellular respiration and ATP levels is observed. To conclude, our results indicate that IF1 is a negative regulator of insulin secretion involved in pancreatic β-cell glucose sensing.
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Affiliation(s)
- Anežka Kahancová
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Filip Sklenář
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Petr Ježek
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Andrea Dlasková
- Department of Mitochondrial Physiology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
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De Marchi U, Hermant A, Thevenet J, Ratinaud Y, Santo-Domingo J, Barron D, Wiederkehr A. A novel ATP-synthase-independent mechanism coupling mitochondrial activation to exocytosis in insulin-secreting cells. J Cell Sci 2017; 130:1929-1939. [PMID: 28404787 DOI: 10.1242/jcs.200741] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 04/11/2017] [Indexed: 12/16/2022] Open
Abstract
Pancreatic β-cells sense glucose, promoting insulin secretion. Glucose sensing requires the sequential stimulation of glycolysis, mitochondrial metabolism and Ca2+ entry. To elucidate how mitochondrial activation in β-cells contributes to insulin secretion, we compared the effects of glucose and the mitochondrial substrate methylsuccinate in the INS-1E insulin-secreting cell line at the respective concentrations at which they maximally activate mitochondrial respiration. Both substrates induced insulin secretion with distinct respiratory profiles, mitochondrial hyperpolarization, NADH production and ATP-to-ADP ratios. In contrast to glucose, methylsuccinate failed to induce large [Ca2+] rises and exocytosis proceeded largely independently of mitochondrial ATP synthesis. Both glucose- and methylsuccinate-induced secretion was blocked by diazoxide, indicating that Ca2+ is required for exocytosis. Dynamic assessment of the redox state of mitochondrial thiols revealed a less marked reduction in response to methylsuccinate than with glucose. Our results demonstrate that insulin exocytosis can be promoted by two distinct mechanisms one of which is dependent on mitochondrial ATP synthesis and large Ca2+ transients, and one of which is independent of mitochondrial ATP synthesis and relies on small Ca2+ signals. We propose that the combined effects of Ca2+ and redox reactions can trigger insulin secretion by these two mechanisms.
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Affiliation(s)
- Umberto De Marchi
- Mitochondrial Function, Nestlé Institute of Health Sciences, EPFL Innovation Park, Building G, Lausanne CH-1015, Switzerland
| | - Aurelie Hermant
- Mitochondrial Function, Nestlé Institute of Health Sciences, EPFL Innovation Park, Building G, Lausanne CH-1015, Switzerland
| | - Jonathan Thevenet
- Mitochondrial Function, Nestlé Institute of Health Sciences, EPFL Innovation Park, Building G, Lausanne CH-1015, Switzerland
| | - Yann Ratinaud
- Natural Bioactives and screening, Nestlé Institute of Health Sciences, EPFL Innovation Park, Building H, Lausanne CH-1015, Switzerland
| | - Jaime Santo-Domingo
- Mitochondrial Function, Nestlé Institute of Health Sciences, EPFL Innovation Park, Building G, Lausanne CH-1015, Switzerland
| | - Denis Barron
- Natural Bioactives and screening, Nestlé Institute of Health Sciences, EPFL Innovation Park, Building H, Lausanne CH-1015, Switzerland
| | - Andreas Wiederkehr
- Mitochondrial Function, Nestlé Institute of Health Sciences, EPFL Innovation Park, Building G, Lausanne CH-1015, Switzerland
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de Souza AH, Santos LRB, Roma LP, Bensellam M, Carpinelli AR, Jonas JC. NADPH oxidase-2 does not contribute to β-cell glucotoxicity in cultured pancreatic islets from C57BL/6J mice. Mol Cell Endocrinol 2017; 439:354-362. [PMID: 27664519 DOI: 10.1016/j.mce.2016.09.022] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 08/24/2016] [Accepted: 09/20/2016] [Indexed: 11/20/2022]
Abstract
High glucose-induced oxidative stress and increased NADPH oxidase-2 (NOX2) activity may contribute to the progressive decline of the functional β-cell mass in type 2 diabetes. To test that hypothesis, we characterized, in islets from male NOX2 knockout (NOX2-KO) and wild-type (WT) C57BL/6J mice cultured for up to 3 weeks at 10 or 30 mmol/l glucose (G10 or G30), the in vitro effects of glucose on cytosolic oxidative stress using probes sensing glutathione oxidation (GRX1-roGFP2), thiol oxidation (roGFP1) or H2O2 (roGFP2-Orp1), on β-cell stimulus-secretion coupling events and on β-cell apoptosis. After 1-2 days of culture in G10, the glucose stimulation of insulin secretion (GSIS) was ∼1.7-fold higher in NOX2-KO vs. WT islets at 20-30 mmol/l glucose despite similar rises in NAD(P)H and intracellular calcium concentration ([Ca2+]i) and no differences in cytosolic GRX1-roGFP2 oxidation. After long-term culture at G10, roGFP1 and roGFP2-Orp1 oxidation and β-cell apoptosis remained low, and the glucose-induced rises in NAD(P)H, [Ca2+]i and GSIS were similarly preserved in both islet types. After prolonged culture at G30, roGFP1 and roGFP2-Orp1 oxidation increased in parallel with β-cell apoptosis, the glucose sensitivity of the NADPH, [Ca2+]i and insulin secretion responses increased, the maximal [Ca2+]i response decreased, but maximal GSIS was preserved. These responses were almost identical in both islet types. In conclusion, NOX2 is a negative regulator of maximal GSIS in C57BL/6J mouse islets, but it does not detectably contribute to the in vitro glucotoxic induction of cytosolic oxidative stress and alterations of β-cell survival and function.
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Affiliation(s)
- Arnaldo H de Souza
- Université catholique de Louvain, Institute of Experimental and Clinical Research, Pole of Endocrinology, Diabetes and Nutrition, Brussels, Belgium; Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Laila R B Santos
- Université catholique de Louvain, Institute of Experimental and Clinical Research, Pole of Endocrinology, Diabetes and Nutrition, Brussels, Belgium
| | - Leticia P Roma
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Mohammed Bensellam
- Université catholique de Louvain, Institute of Experimental and Clinical Research, Pole of Endocrinology, Diabetes and Nutrition, Brussels, Belgium
| | - Angelo R Carpinelli
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Jean-Christophe Jonas
- Université catholique de Louvain, Institute of Experimental and Clinical Research, Pole of Endocrinology, Diabetes and Nutrition, Brussels, Belgium.
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Ježek J, Dlasková A, Zelenka J, Jabůrek M, Ježek P. H₂O₂-Activated Mitochondrial Phospholipase iPLA₂γ Prevents Lipotoxic Oxidative Stress in Synergy with UCP2, Amplifies Signaling via G-Protein-Coupled Receptor GPR40, and Regulates Insulin Secretion in Pancreatic β-Cells. Antioxid Redox Signal 2015; 23:958-72. [PMID: 25925080 PMCID: PMC4623989 DOI: 10.1089/ars.2014.6195] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
AIMS Pancreatic β-cell chronic lipotoxicity evolves from acute free fatty acid (FA)-mediated oxidative stress, unprotected by antioxidant mechanisms. Since mitochondrial uncoupling protein-2 (UCP2) plays antioxidant and insulin-regulating roles in pancreatic β-cells, we tested our hypothesis, that UCP2-mediated uncoupling attenuating mitochondrial superoxide production is initiated by FA release due to a direct H2O2-induced activation of mitochondrial phospholipase iPLA2γ. RESULTS Pro-oxidant tert-butylhydroperoxide increased respiration, decreased membrane potential and mitochondrial matrix superoxide release rates of control but not UCP2- or iPLA2γ-silenced INS-1E cells. iPLA2γ/UCP2-mediated uncoupling was alternatively activated by an H2O2 burst, resulting from palmitic acid (PA) β-oxidation, and it was prevented by antioxidants or catalase overexpression. Exclusively, nascent FAs that cleaved off phospholipids by iPLA2γ were capable of activating UCP2, indicating that the previously reported direct redox UCP2 activation is actually indirect. Glucose-stimulated insulin release was not affected by UCP2 or iPLA2γ silencing, unless pro-oxidant activation had taken place. PA augmented insulin secretion via G-protein-coupled receptor 40 (GPR40), stimulated by iPLA2γ-cleaved FAs (absent after GPR40 silencing). INNOVATION AND CONCLUSION The iPLA2γ/UCP2 synergy provides a feedback antioxidant mechanism preventing oxidative stress by physiological FA intake in pancreatic β-cells, regulating glucose-, FA-, and redox-stimulated insulin secretion. iPLA2γ is regulated by exogenous FA via β-oxidation causing H2O2 signaling, while FAs are cleaved off phospholipids, subsequently acting as amplifying messengers for GPR40. Hence, iPLA2γ acts in eminent physiological redox signaling, the impairment of which results in the lack of antilipotoxic defense and contributes to chronic lipotoxicity.
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Affiliation(s)
- Jan Ježek
- Department of Membrane Transport Biophysics, Institute of Physiology , Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Andrea Dlasková
- Department of Membrane Transport Biophysics, Institute of Physiology , Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Jaroslav Zelenka
- Department of Membrane Transport Biophysics, Institute of Physiology , Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Martin Jabůrek
- Department of Membrane Transport Biophysics, Institute of Physiology , Academy of Sciences of the Czech Republic, Prague, Czech Republic
| | - Petr Ježek
- Department of Membrane Transport Biophysics, Institute of Physiology , Academy of Sciences of the Czech Republic, Prague, Czech Republic
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Paharkova V, Alvarez G, Nakamura H, Cohen P, Lee KW. Rat Humanin is encoded and translated in mitochondria and is localized to the mitochondrial compartment where it regulates ROS production. Mol Cell Endocrinol 2015; 413:96-100. [PMID: 26116236 DOI: 10.1016/j.mce.2015.06.015] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Revised: 06/09/2015] [Accepted: 06/10/2015] [Indexed: 10/23/2022]
Abstract
Evidence for the putative mitochondrial origin of the Humanin (HN) peptide has been lacking, although its cytoprotective activity has been demonstrated in a variety of organismal and cellular systems. We sought to establish proof-of-principle for a mitochondria-derived peptide (MDP) in a rat-derived cellular system as the rat HN sequence is predicted to lack nuclear insertions of mitochondrial origin (NUMT). We found that the rat HN (Rattin; rHN) homologue is derived from the mitochondrial genome as evidenced by decreased production in Rho-0 cells, and that peptide translation occurs in the mitochondria as it is unaffected by cycloheximide. Rat HN localizes to the mitochondria in cellular subfractionation and immunohistochemical studies. Addition of a HN analogue to isolated mitochondria from rat INS-1 beta cells reduced hydrogen peroxide production by 55%. In summary, a locally bioactive peptide is derived and translated from an open reading frame (ORF) within rat mitochondrial DNA encoding 16S rRNA.
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Affiliation(s)
- Vladislava Paharkova
- Pediatric Endocrinology, Mattel Children's Hospital UCLA; David Geffen School of Medicine at UCLA, USA
| | - Griselda Alvarez
- Pediatric Endocrinology, Mattel Children's Hospital UCLA; David Geffen School of Medicine at UCLA, USA
| | - Hiromi Nakamura
- Pediatric Endocrinology, Mattel Children's Hospital UCLA; David Geffen School of Medicine at UCLA, USA
| | - Pinchas Cohen
- Davis School of Gerontology, University of Southern California, USA
| | - Kuk-Wha Lee
- Pediatric Endocrinology, Mattel Children's Hospital UCLA; David Geffen School of Medicine at UCLA, USA.
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18
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Chokeberry Anthocyanin Extract as Pancreatic β-Cell Protectors in Two Models of Induced Oxidative Stress. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2015; 2015:429075. [PMID: 26113953 PMCID: PMC4465716 DOI: 10.1155/2015/429075] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Revised: 04/29/2015] [Accepted: 05/03/2015] [Indexed: 01/30/2023]
Abstract
The aim of this study was to investigate the protective effects of a chokeberry anthocyanin extract (CAE) on pancreatic β-cells (βTC3) exposed to hydrogen peroxide- (H2O2-) and high glucose- (HG-) induced oxidative stress conditions. In order to quantify individual anthocyanins high performance liquid chromatography (HPLC) coupled to photodiode array (PDA) was used. The identification of the fragment ion pattern of anthocyanins was carried out by electrospray ionization mass spectrometry (LC-ESI-MS). The results showed that physiologically achievable concentrations of CAE (1, 5, and 10 μM) protect βTC3 against H2O2- and HG-induced cytotoxicity. Antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) were increased in pancreatic β-cells pretreated with CAE compared to cells exposed to the prooxidant agents. GSH levels initially reduced after exposure to H2O2 and HG were restored by pretreatment with CAE. Insulin secretion in βTC3 cells was enhanced by CAE pretreatment. CAE restored the insulin pool and diminished the intracellular reactive oxygen species level in glucose-induced stress condition in βTC3 cells. These results demonstrate that anthocyanins from CAE were biologically active, showing a secretagogue potential and an antioxidative protection of enzymatic systems, conferring protection against H2O2 and glucose toxicity in βTC3 cells.
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19
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Kim JY, Lee DY, Lee YJ, Park KJ, Kim KH, Kim JW, Kim WH. Chronic alcohol consumption potentiates the development of diabetes through pancreatic β-cell dysfunction. World J Biol Chem 2015; 6:1-15. [PMID: 25717351 PMCID: PMC4317634 DOI: 10.4331/wjbc.v6.i1.1] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2014] [Revised: 10/29/2014] [Accepted: 12/10/2014] [Indexed: 02/05/2023] Open
Abstract
Chronic ethanol consumption is well established as a major risk factor for type-2 diabetes (T2D), which is evidenced by impaired glucose metabolism and insulin resistance. However, the relationships between alcohol consumption and the development of T2D remain controversial. In particular, the direct effects of ethanol consumption on proliferation of pancreatic β-cell and the exact mechanisms associated with ethanol-mediated β-cell dysfunction and apoptosis remain elusive. Although alcoholism and alcohol consumption are prevalent and represent crucial public health problems worldwide, many people believe that low-to-moderate ethanol consumption may protect against T2D and cardiovascular diseases. However, the J- or U-shaped curves obtained from cross-sectional and large prospective studies have not fully explained the relationship between alcohol consumption and T2D. This review provides evidence for the harmful effects of chronic ethanol consumption on the progressive development of T2D, particularly with respect to pancreatic β-cell mass and function in association with insulin synthesis and secretion. This review also discusses a conceptual framework for how ethanol-produced peroxynitrite contributes to pancreatic β-cell dysfunction and metabolic syndrome.
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20
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Alán L, Olejár T, Cahová M, Zelenka J, Berková Z, Smětáková M, Saudek F, Matěj R, Ježek P. Delta Cell Hyperplasia in Adult Goto-Kakizaki (GK/MolTac) Diabetic Rats. J Diabetes Res 2015; 2015:385395. [PMID: 26236746 PMCID: PMC4506919 DOI: 10.1155/2015/385395] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 05/22/2015] [Accepted: 05/31/2015] [Indexed: 01/23/2023] Open
Abstract
Reduced beta cell mass in pancreatic islets (PI) of Goto-Kakizaki (GK) rats is frequently observed in this diabetic model, but knowledge on delta cells is scarce. Aiming to compare delta cell physiology/pathology of GK to Wistar rats, we found that delta cell number increased over time as did somatostatin mRNA and delta cells distribution in PI is different in GK rats. Subtle changes in 6-week-old GK rats were found. With maturation and aging of GK rats, disturbed cytoarchitecture occurred with irregular beta cells accompanied by delta cell hyperplasia and loss of pancreatic polypeptide (PPY) positivity. Unlike the constant glucose-stimulation index for insulin PI release in Wistar rats, this index declined with GK age, whereas for somatostatin it increased with age. A decrease of GK rat PPY serum levels was found. GK rat body weight decreased with increasing hyperglycemia. Somatostatin analog octreotide completely blocked insulin secretion, impaired proliferation at low autocrine insulin, and decreased PPY secretion and mitochondrial DNA in INS-1E cells. In conclusion, in GK rats PI, significant local delta cell hyperplasia and suspected paracrine effect of somatostatin diminish beta cell viability and contribute to the deterioration of beta cell mass. Altered PPY-secreting cells distribution amends another component of GK PI's pathophysiology.
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Affiliation(s)
- Lukáš Alán
- Department No. 75, Institute of Physiology, Academy of Sciences, 14220 Prague, Czech Republic
| | - Tomáš Olejár
- Department No. 75, Institute of Physiology, Academy of Sciences, 14220 Prague, Czech Republic
| | - Monika Cahová
- Institute of Clinical & Experimental Medicine, 14021 Prague, Czech Republic
| | - Jaroslav Zelenka
- Department No. 75, Institute of Physiology, Academy of Sciences, 14220 Prague, Czech Republic
| | - Zuzana Berková
- Institute of Clinical & Experimental Medicine, 14021 Prague, Czech Republic
| | - Magdalena Smětáková
- Teaching Thomayer Hospital and Third Medical School, Charles University, 14059 Prague, Czech Republic
| | - František Saudek
- Institute of Clinical & Experimental Medicine, 14021 Prague, Czech Republic
| | - Radoslav Matěj
- Teaching Thomayer Hospital and Third Medical School, Charles University, 14059 Prague, Czech Republic
| | - Petr Ježek
- Department No. 75, Institute of Physiology, Academy of Sciences, 14220 Prague, Czech Republic
- *Petr Ježek:
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Kang L, Dai C, Lustig ME, Bonner JS, Mayes WH, Mokshagundam S, James FD, Thompson CS, Lin CT, Perry CGR, Anderson EJ, Neufer PD, Wasserman DH, Powers AC. Heterozygous SOD2 deletion impairs glucose-stimulated insulin secretion, but not insulin action, in high-fat-fed mice. Diabetes 2014; 63:3699-710. [PMID: 24947366 PMCID: PMC4207395 DOI: 10.2337/db13-1845] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Elevated reactive oxygen species (ROS) are linked to insulin resistance and islet dysfunction. Manganese superoxide dismutase (SOD2) is a primary defense against mitochondrial oxidative stress. To test the hypothesis that heterozygous SOD2 deletion impairs glucose-stimulated insulin secretion (GSIS) and insulin action, wild-type (sod2(+/+)) and heterozygous knockout mice (sod2(+/-)) were fed a chow or high-fat (HF) diet, which accelerates ROS production. Hyperglycemic (HG) and hyperinsulinemic-euglycemic (HI) clamps were performed to assess GSIS and insulin action in vivo. GSIS during HG clamps was equal in chow-fed sod2(+/-) and sod2(+/+) but was markedly decreased in HF-fed sod2(+/-). Remarkably, this impairment was not paralleled by reduced HG glucose infusion rate (GIR). Decreased GSIS in HF-fed sod2(+/-) was associated with increased ROS, such as superoxide ion. Surprisingly, insulin action determined by HI clamps did not differ between sod2(+/-) and sod2(+/+) of either diet. Since insulin action was unaffected, we hypothesized that the unchanged HG GIR in HF-fed sod2(+/-) was due to increased glucose effectiveness. Increased GLUT-1, hexokinase II, and phospho-AMPK protein in muscle of HF-fed sod2(+/-) support this hypothesis. We conclude that heterozygous SOD2 deletion in mice, a model that mimics SOD2 changes observed in diabetic humans, impairs GSIS in HF-fed mice without affecting insulin action.
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Affiliation(s)
- Li Kang
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN Mouse Metabolic Phenotyping Center, Vanderbilt University, Nashville, TN Division of Cardiovascular and Diabetes Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee, U.K.
| | - Chunhua Dai
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University, Nashville, TN
| | - Mary E Lustig
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | - Jeffrey S Bonner
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | - Wesley H Mayes
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | - Shilpa Mokshagundam
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | - Freyja D James
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN
| | - Courtney S Thompson
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University, Nashville, TN
| | - Chien-Te Lin
- East Carolina Diabetes and Obesity Institute and Departments of Physiology and Kinesiology, East Carolina University, Greenville, NC
| | - Christopher G R Perry
- East Carolina Diabetes and Obesity Institute and Departments of Physiology and Kinesiology, East Carolina University, Greenville, NC
| | - Ethan J Anderson
- East Carolina Diabetes and Obesity Institute and Departments of Physiology and Kinesiology, East Carolina University, Greenville, NC
| | - P Darrell Neufer
- East Carolina Diabetes and Obesity Institute and Departments of Physiology and Kinesiology, East Carolina University, Greenville, NC
| | - David H Wasserman
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN Mouse Metabolic Phenotyping Center, Vanderbilt University, Nashville, TN
| | - Alvin C Powers
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University, Nashville, TN Veterans Affairs Tennessee Valley Healthcare System, Nashville, TN
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De Long NE, Hyslop JR, Raha S, Hardy DB, Holloway AC. Fluoxetine-induced pancreatic beta cell dysfunction: New insight into the benefits of folic acid in the treatment of depression. J Affect Disord 2014; 166:6-13. [PMID: 25012404 DOI: 10.1016/j.jad.2014.04.063] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 04/25/2014] [Indexed: 01/10/2023]
Abstract
BACKGROUND Major depressive disorder is a common psychiatric illness with reported prevalence rates of 12-16% in persons aged 12 and over. Depression is also associated with a high risk of new onset of type 2 diabetes (T2D). This relationship between depression and diabetes may be related to depression itself and/or drugs prescribed. Importantly, the use of selective serotonin reuptake inhibitors (SSRIs), the most commonly prescribed class of antidepressants, increases the risk of developing T2D. However, the mechanism(s) underlying this association remains elusive. METHODS Here we examine the effects of the SSRI fluoxetine (Prozac®) on beta cell function utilizing INS-1E cells, a rat beta cell line, to elucidate the underlying molecular mechanisms. RESULTS Fluoxetine treatment significantly reduced glucose stimulated insulin secretion (GSIS). This decreased beta cell function was concomitant with an increased production of reactive oxygen species and oxidative damage which may contribute to decreased mitochondrial electron transport chain enzyme (ETC) activity. Importantly the fluoxetine-induced deficits in beta cell function were prevented by the addition of the antioxidant folic acid. LIMITATIONS These studies were conducted in vitro; the in vivo relevance remains to be determined. CONCLUSIONS These findings suggest that use of SSRI antidepressants may increase the risk of new-onset T2D by causing oxidative stress in pancreatic beta cells. However, folic acid supplementation in patients taking SSRIs may reduce the risk of new onset diabetes via protection of normal beta cell function.
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Affiliation(s)
- Nicole E De Long
- Department of Obstetrics and Gynecology, McMaster University, RM HSC-3N52 1280 Main Street West, Hamilton, ON, Canada L8S 4K1
| | - Jillian R Hyslop
- Department of Obstetrics and Gynecology, McMaster University, RM HSC-3N52 1280 Main Street West, Hamilton, ON, Canada L8S 4K1
| | - Sandeep Raha
- Department of Pediatrics, McMaster University, Hamilton, ON, Canada L8S 4K1
| | - Daniel B Hardy
- Departments of Obstetrics and Gynecology and Physiology and Pharmacology, Western University, London, ON, Canada N6A5C1
| | - Alison C Holloway
- Department of Obstetrics and Gynecology, McMaster University, RM HSC-3N52 1280 Main Street West, Hamilton, ON, Canada L8S 4K1.
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JEŽEK P, OLEJÁR T, SMOLKOVÁ K, JEŽEK J, DLASKOVÁ A, PLECITÁ-HLAVATÁ L, ZELENKA J, ŠPAČEK T, ENGSTOVÁ H, PAJUELO REGUERA D, JABŮREK M. Antioxidant and Regulatory Role of Mitochondrial Uncoupling Protein UCP2 in Pancreatic β-cells. Physiol Res 2014; 63:S73-91. [DOI: 10.33549/physiolres.932633] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Research on brown adipose tissue and its hallmark protein, mitochondrial uncoupling protein UCP1, has been conducted for half a century and has been traditionally studied in the Institute of Physiology (AS CR, Prague), likewise UCP2 residing in multiple tissues for the last two decades. Our group has significantly contributed to the elucidation of UCP uncoupling mechanism, fully dependent on free fatty acids (FFAs) within the inner mitochondrial membrane. Now we review UCP2 physiological roles emphasizing its roles in pancreatic β-cells, such as antioxidant role, possible tuning of redox homeostasis (consequently UCP2 participation in redox regulations), and fine regulation of glucose-stimulated insulin secretion (GSIS). For example, NADPH has been firmly established as being a modulator of GSIS and since UCP2 may influence redox homeostasis, it likely affects NADPH levels. We also point out the role of phospholipase iPLA2 isoform in providing FFAs for the UCP2 antioxidant function. Such initiation of mild uncoupling hypothetically precedes lipotoxicity in pancreatic β-cells until it reaches the pathological threshold, after which the antioxidant role of UCP2 can be no more cell-protective, for example due to oxidative stress-accumulated mutations in mtDNA. These mechanisms, together with impaired autocrine insulin function belong to important causes of Type 2 diabetes etiology.
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Affiliation(s)
- P. JEŽEK
- Department of Membrane Transport Biophysics, Institute of Physiology Academy of Sciences of the Czech Republic, Prague, Czech Republic
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Ergin V, Hariry RE, Karasu C. Carbonyl stress in aging process: role of vitamins and phytochemicals as redox regulators. Aging Dis 2013; 4:276-94. [PMID: 24124633 DOI: 10.14336/ad.2013.0400276] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 08/01/2013] [Accepted: 08/02/2013] [Indexed: 12/15/2022] Open
Abstract
There is a growing scientific agreement that the cellular redox regulators such as antioxidants, particularly the natural polyphenolic forms, may help lower the incidence of some pathologies, including metabolic diseases like diabetes and diabesity, cardiovascular and neurodegenerative abnormalities, and certain cancers or even have anti-aging properties. The recent researches indicate that the degree of metabolic modulation and adaptation response of cells to reductants as well as oxidants establish their survival and homeostasis, which is linked with very critical balance in imbalances in cellular redox capacity and signaling, and that might be an answer the questions why some antioxidants or phytochemicals potentially could do more harm than good, or why some proteins lose their function by increase interactions with glyco- and lipo-oxidation mediates in the cells (carbonyl stress). Nonetheless, pursue of healthy aging has led the use of antioxidants as a means to disrupt age-associated physiological dysfunctions, dysregulated metabolic processes or prevention of many age-related diseases. Although it is still early to define their exact clinical benefits for treating age-related disease, a diet rich in polyphenolic or other forms of antioxidants does seem to offer hope in delaying the onset of age-related disorders. It is now clear that any deficiency in antioxidant vitamins, inadequate enzymatic antioxidant defenses can distinctive for many age-related disease, and protein carbonylation can used as an indicator of oxidative stress associated diseases and aging status. This review examines antioxidant compounds and plant polyphenols as redox regulators in health, disease and aging processes with hope that a better understanding of the many mechanisms involved with these distinct compounds, which may lead to better health and novel treatment approaches for age-related diseases.
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Affiliation(s)
- Volkan Ergin
- Cellular Stress Response and Signal Transduction Research Laboratory, Department of Medical Pharmacology, Faculty of Medicine, Gazi University, Ankara, Turkey
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