1
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Kowluru A. Regulatory roles of CARD9-BCL10-Rac1 (CBR) signalome in islet β-cell function in health and metabolic stress: Is there room for MALT1? Biochem Pharmacol 2023; 218:115889. [PMID: 37991197 PMCID: PMC10872519 DOI: 10.1016/j.bcp.2023.115889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 10/20/2023] [Accepted: 10/23/2023] [Indexed: 11/23/2023]
Abstract
It is widely accepted that pancreatic islet β-cell failure and the onset of type 2 diabetes (T2DM) constitute an intricate interplay between the genetic expression of the disease and a host of intracellular events including increased metabolic (oxidative, endoplasmic reticulum) stress under the duress of glucolipotoxicity. Emerging evidence implicates unique roles for Caspase Recruitment Domain containing protein 9 (CARD9) in the onset of metabolic diseases, including obesity and insulin resistance. Mechanistically, CARD9 has been implicated in the regulation of p38MAPK and NFkB signaling pathways culminating in cellular dysfunction. Several regulatory factors, including B-cell lymphoma/leukemia 10 (BCL10) have been identified as modulators of CARD9 function in multiple cell types. Despite this evidence on regulatory roles of CARD9-BCL10 signalome in the onset of various pathological states, putative roles of this signaling module in islet β-cell dysfunction in metabolic stress remain less understood. This brief review is aimed at highlighting roles for CARD9 in islet β-cell function under acute (physiological insulin secretion) and long-term (cell dysfunction) exposure to glucose. Emerging roles of other signaling proteins, such as Rac1, BCL10 and MALT1 as contributors to CARD9 signaling in the islet β-cells are also reviewed. Potential avenues for future research toward the development of novel therapeutics for the prevention CARD9-BCL10-Rac1 (CBR) signalome-induced β-cell defects under metabolic stress are discussed.
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Affiliation(s)
- Anjaneyulu Kowluru
- Biomedical Research Service, John D. Dingell VA Medical Center, and Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI 48201, USA.
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2
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Sun Y, Guo LQ, Wang DG, Xing YJ, Bai YP, Zhang T, Wang W, Zhou SM, Yao XM, Cheng JH, Chang WW, Lv K, Li CX, Kong X. Metformin alleviates glucolipotoxicity-induced pancreatic β cell ferroptosis through regulation of the GPX4/ACSL4 axis. Eur J Pharmacol 2023; 956:175967. [PMID: 37549729 DOI: 10.1016/j.ejphar.2023.175967] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 07/05/2023] [Accepted: 08/04/2023] [Indexed: 08/09/2023]
Abstract
Ferroptosis, a new type of cell death, is associated with pancreatic β cell damage. However, the role of glucolipotoxicity in inducing β cell ferroptosis remains unclear. Metformin (Met), exenatide (Exe), and saxagliptin (Sax) are frequently used anti-hyperglycaemic drugs. However, their protective effects on β cells through ferroptosis modulation are not well-established. In this study, we observed significant ferroptosis in NIT-1 cells and primary mouse islets after exposure to high glucose and palmitate (HG/PA). Compared to Exe and Sax, Met significantly alleviated glucolipotoxicity-induced pancreatic β cell ferroptosis. Blocking the activity of glutathione peroxidase 4 (GPX4) with Ras-selective lethal 3 or inhibiting its expression by small interfering RNA transfection significantly attenuated the anti-ferroptosis effects of Met. Mechanistically, Met alleviates HG/PA-induced β cell ferroptosis by regulating the GPX4/ACSL4 axis. Collectively, our findings highlight the significance of ferroptosis in pancreatic β cell glucolipotoxicity-induced injury and provide novel insights into the protective effects of Met on islet β cells.
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Affiliation(s)
- Yue Sun
- Department of Gerontology, Geriatric Endocrinology Unit, The First Affiliated Hospital of Wannan Medical College, Yijishan Hospital, Wuhu, 241001, China; Anhui Provincial Key Laboratory of Non-coding RNA Basic and Clinical Transformation, Wannan Medical College, Wuhu, 241002, China.
| | - Li-Qun Guo
- Department of Pharmacology, Wannan Medical College, Wuhu, 241002, China.
| | - De-Guo Wang
- Department of Gerontology, Geriatric Endocrinology Unit, The First Affiliated Hospital of Wannan Medical College, Yijishan Hospital, Wuhu, 241001, China.
| | - Yu-Jie Xing
- Department of Gerontology, Geriatric Endocrinology Unit, The First Affiliated Hospital of Wannan Medical College, Yijishan Hospital, Wuhu, 241001, China; Anhui Provincial Key Laboratory of Non-coding RNA Basic and Clinical Transformation, Wannan Medical College, Wuhu, 241002, China.
| | - Ya-Ping Bai
- Anhui Provincial Key Laboratory of Non-coding RNA Basic and Clinical Transformation, Wannan Medical College, Wuhu, 241002, China; Anhui Provincial Key Laboratory of Molecular Enzymology and Mechanism of Major Diseases, College of Life Sciences, Anhui Normal University, Wuhu, 241000, China.
| | - Teng Zhang
- Anhui Provincial Key Laboratory of Non-coding RNA Basic and Clinical Transformation, Wannan Medical College, Wuhu, 241002, China.
| | - Wen Wang
- Anhui Provincial Key Laboratory of Non-coding RNA Basic and Clinical Transformation, Wannan Medical College, Wuhu, 241002, China.
| | - Si-Min Zhou
- Department of Gerontology, Geriatric Endocrinology Unit, The First Affiliated Hospital of Wannan Medical College, Yijishan Hospital, Wuhu, 241001, China; Anhui Provincial Key Laboratory of Non-coding RNA Basic and Clinical Transformation, Wannan Medical College, Wuhu, 241002, China.
| | - Xin-Ming Yao
- Department of Endocrinology, The First Affiliated Hospital of Wannan Medical College, Yijishan Hospital, Wuhu, 241001, China.
| | - Jin-Han Cheng
- Department of Endocrinology, The First Affiliated Hospital of Wannan Medical College, Yijishan Hospital, Wuhu, 241001, China.
| | - Wei-Wei Chang
- Department of Epidemiology and Health Statistics, School of Public Health, Wannan Medical College, Wuhu, 241002, Anhui, China.
| | - Kun Lv
- Anhui Provincial Key Laboratory of Non-coding RNA Basic and Clinical Transformation, Wannan Medical College, Wuhu, 241002, China; Central Laboratory of Yijishan Hospital, Wuhu, 241001, China; Anhui Provincial Key Laboratory of Molecular Enzymology and Mechanism of Major Diseases, College of Life Sciences, Anhui Normal University, Wuhu, 241000, China.
| | - Chun-Xiao Li
- Department of Dermatology, Xinhua Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200092, China.
| | - Xiang Kong
- Department of Gerontology, Geriatric Endocrinology Unit, The First Affiliated Hospital of Wannan Medical College, Yijishan Hospital, Wuhu, 241001, China; Anhui Provincial Key Laboratory of Non-coding RNA Basic and Clinical Transformation, Wannan Medical College, Wuhu, 241002, China; Central Laboratory of Yijishan Hospital, Wuhu, 241001, China; Anhui Provincial Key Laboratory of Molecular Enzymology and Mechanism of Major Diseases, College of Life Sciences, Anhui Normal University, Wuhu, 241000, China.
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3
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Malaekeh-Nikouei A, Shokri-Naei S, Karbasforoushan S, Bahari H, Baradaran Rahimi V, Heidari R, Askari VR. Metformin beyond an anti-diabetic agent: A comprehensive and mechanistic review on its effects against natural and chemical toxins. Biomed Pharmacother 2023; 165:115263. [PMID: 37541178 DOI: 10.1016/j.biopha.2023.115263] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 07/24/2023] [Accepted: 07/31/2023] [Indexed: 08/06/2023] Open
Abstract
In addition to the anti-diabetic effect of metformin, a growing number of studies have shown that metformin has some exciting properties, such as anti-oxidative capabilities, anticancer, genomic stability, anti-inflammation, and anti-fibrosis, which have potent, that can treat other disorders other than diabetes mellitus. We aimed to describe and review the protective and antidotal efficacy of metformin against biologicals, chemicals, natural, medications, pesticides, and radiation-induced toxicities. A comprehensive search has been performed from Scopus, Web of Science, PubMed, and Google Scholar databases from inception to March 8, 2023. All in vitro, in vivo, and clinical studies were considered. Many studies suggest that metformin affects diseases other than diabetes. It is a radioprotective and chemoprotective drug that also affects viral and bacterial diseases. It can be used against inflammation-related and apoptosis-related abnormalities and against toxins to lower their effects. Besides lowering blood sugar, metformin can attenuate the effects of toxins on body weight, inflammation, apoptosis, necrosis, caspase-3 activation, cell viability and survival rate, reactive oxygen species (ROS), NF-κB, TNF-α, many interleukins, lipid profile, and many enzymes activity such as catalase and superoxide dismutase. It also can reduce the histopathological damages induced by many toxins on the kidneys, liver, and colon. However, clinical trials and human studies are needed before using metformin as a therapeutic agent against other diseases.
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Affiliation(s)
- Amirhossein Malaekeh-Nikouei
- International UNESCO Center for Health-Related Basic Sciences and Human Nutrition, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Sina Shokri-Naei
- International UNESCO Center for Health-Related Basic Sciences and Human Nutrition, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Sobhan Karbasforoushan
- International UNESCO Center for Health-Related Basic Sciences and Human Nutrition, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Hossein Bahari
- International UNESCO Center for Health-Related Basic Sciences and Human Nutrition, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Vafa Baradaran Rahimi
- Department of Cardiovascular Diseases, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Reza Heidari
- Medical Biotechnology Research Center, AJA University of Medical Sciences, Tehran, Iran; Research Center for Cancer Screening and Epidemiology, AJA University of Medical Sciences, Tehran, Iran
| | - Vahid Reza Askari
- International UNESCO Center for Health-Related Basic Sciences and Human Nutrition, Mashhad University of Medical Sciences, Mashhad, Iran; Pharmacological Research Center of Medicinal Plants, Mashhad University of Medical Sciences, Mashhad, Iran.
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4
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Dalle S, Abderrahmani A, Renard E. Pharmacological inhibitors of β-cell dysfunction and death as therapeutics for diabetes. Front Endocrinol (Lausanne) 2023; 14:1076343. [PMID: 37008937 PMCID: PMC10050720 DOI: 10.3389/fendo.2023.1076343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 02/20/2023] [Indexed: 03/17/2023] Open
Abstract
More than 500 million adults suffer from diabetes worldwide, and this number is constantly increasing. Diabetes causes 5 million deaths per year and huge healthcare costs per year. β-cell death is the major cause of type 1 diabetes. β-cell secretory dysfunction plays a key role in the development of type 2 diabetes. A loss of β-cell mass due to apoptotic death has also been proposed as critical for the pathogenesis of type 2 diabetes. Death of β-cells is caused by multiple factors including pro-inflammatory cytokines, chronic hyperglycemia (glucotoxicity), certain fatty acids at high concentrations (lipotoxicity), reactive oxygen species, endoplasmic reticulum stress, and islet amyloid deposits. Unfortunately, none of the currently available antidiabetic drugs favor the maintenance of endogenous β-cell functional mass, indicating an unmet medical need. Here, we comprehensively review over the last ten years the investigation and identification of molecules of pharmacological interest for protecting β-cells against dysfunction and apoptotic death which could pave the way for the development of innovative therapies for diabetes.
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Affiliation(s)
- Stéphane Dalle
- Institut de Génomique Fonctionnelle, Université de Montpellier, Centre National de la Recherche Scientifique (CNRS), Institut National de la Santé et de la Recherche Médicale (INSERM), Montpellier, France
| | - Amar Abderrahmani
- Université Lille, Centre National de la Recherche Scientifique (CNRS), Centrale Lille, Polytechnique Hauts-de-France, UMR 8520, IEMN, Lille, France
| | - Eric Renard
- Institut de Génomique Fonctionnelle, Université de Montpellier, Centre National de la Recherche Scientifique (CNRS), Institut National de la Santé et de la Recherche Médicale (INSERM), Montpellier, France
- Laboratoire de Thérapie Cellulaire du Diabète, Centre Hospitalier Universitaire, Montpellier, France
- Département d’Endocrinologie, Diabètologie, Centre Hospitalier Universitaire, Montpellier, France
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5
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Hali M, Wadzinski BE, Kowluru A. Alpha4 contributes to the dysfunction of the pancreatic beta cell under metabolic stress. Mol Cell Endocrinol 2022; 557:111754. [PMID: 35987388 PMCID: PMC9620510 DOI: 10.1016/j.mce.2022.111754] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 08/10/2022] [Accepted: 08/12/2022] [Indexed: 11/30/2022]
Abstract
The current study examined the roles of Alpha4, a non-canonical subunit of protein phosphatase 2A, in the regulation of acute (insulin secretion) and chronic (cell dysfunction) effects of glucose in pancreatic beta cells. Alpha4 is expressed in human islets, rat islets and INS-1832/13 cells. Incubation of INS-1832/13 cells and rat islets with high glucose (HG) significantly increased the expression of Alpha4. C2-Ceramide, a biologically active sphingolipid, also increased the expression of Alpha4 in INS-1832/13 cells and rat islets. Subcellular distribution studies of Alpha4 in low glucose (LG) and HG exposed INS-1832/13 cells revealed that it is predominantly cytosolic, and its expression is significantly increased in the non-nuclear/cytosolic fractions in cells exposed to HG. siRNA-mediated knockdown of Alpha4 exerted minimal effects on glucose- or KCl-induced insulin secretion. siRNA-mediated deletion of Alpha4 significantly increased p38MAPK and JNK1/2 phosphorylation under LG conditions, comparable to the degree seen under HG conditions. Paradoxically, a significant potentiation of HG-induced p38MAPK and JNK2 phosphorylation was noted following Alpha4 deletion. HG-induced CHOP expression (ER stress marker) and caspase-3 activation were markedly attenuated in cells following Alpha4 knockdown. Deletion of Alpha4 in INS-1832/13 cells prevented HG-induced loss in the expression of Connexin36, a gap junction channel protein, which has been implicated in normal beta cell function. Lastly, depletion of endogenous Alpha4 significantly reduced HG-induced cell death in INS-1832/13 cells. Based on these findings we conclude that Alpha4 contributes to HG-induced metabolic dysfunction of the islet beta cell.
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Affiliation(s)
- Mirabela Hali
- Biomedical Research Service, John D. Dingell VA Medical Center, Detroit, MI, USA; Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, USA
| | - Brian E Wadzinski
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Anjaneyulu Kowluru
- Biomedical Research Service, John D. Dingell VA Medical Center, Detroit, MI, USA; Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, USA.
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6
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Kowluru A, Gleason NF. Underappreciated roles for Rho GDP dissociation inhibitors (RhoGDIs) in cell function: Lessons learned from the pancreatic islet β-cell. Biochem Pharmacol 2022; 197:114886. [PMID: 34968495 PMCID: PMC8858860 DOI: 10.1016/j.bcp.2021.114886] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 12/10/2021] [Accepted: 12/13/2021] [Indexed: 11/02/2022]
Abstract
Rho subfamily of G proteins (e.g., Rac1) have been implicated in glucose-stimulated insulin secretion from the pancreatic β-cell. Interestingly, metabolic stress (e.g., chronic exposure to high glucose) results in sustained activation of Rac1 leading to increased oxidative stress, impaired insulin secretion and β-cell dysfunction. Activation-deactivation of Rho G proteins is mediated by three classes of regulatory proteins, namely the guanine nucleotide exchange factors (GEFs), which facilitate the conversion of inactive G proteins to their active conformations; the GTPase-activating proteins (GAPs), which convert the active G proteins to their inactive forms); and the GDP-dissociation inhibitors (GDIs), which prevent the dissociation of GDP from G proteins. Contrary to a large number of GEFs (82 members) and GAPs (69 members), only three members of RhoGDIs (RhoGDIα, RhoGDIβ and RhoGDIγ) are expressed in mammalian cells.Even though relatively smaller in number, the GDIs appear to play essential roles in G protein function (e.g., subcellular targeting) for effector activation and cell regulation. Emerging evidence also suggests that the GDIs are functionally regulated via post-translational modification (e.g., phosphorylation) and by lipid second messengers, lipid kinases and lipid phosphatases. We highlight the underappreciated regulatory roles of RhoGDI-Rho G protein signalome in islet β-cell function in health and metabolic stress. Potential knowledge gaps in the field, and directions for future research for the identification of novel therapeutic targets to loss of functional β-cell mass under the duress of metabolic stress are highlighted.
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Affiliation(s)
- Anjaneyulu Kowluru
- Biomedical Research Service, John D. Dingell VA Medical Center and Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI 48201, USA.
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7
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Valle MMR, Vilas-Boas EA, Lucena CF, Teixeira SA, Muscara MN, Carpinelli AR. Metformin disrupts insulin secretion, causes proapoptotic and oxidative effects in rat pancreatic beta-cells in vitro. J Biochem Mol Toxicol 2022; 36:e23007. [PMID: 35199402 DOI: 10.1002/jbt.23007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 11/28/2021] [Accepted: 01/04/2022] [Indexed: 11/07/2022]
Abstract
Metformin is the first-line drug to treat type 2 diabetes mellitus. Its mechanism of action is still debatable, and recent studies report that metformin attenuates oxidative stress. This study evaluated the in vitro antioxidant effects of a broad range of metformin concentrations on insulin-producing cells. The cell cycle, metabolism, glucose-stimulated insulin secretion, and cell death were evaluated to determine the biguanide effects on beta-cell function and survival. Antioxidant potential was based on reactive oxygen species (ROS), reduced glutathione (GSH), oxidative stress biomarker levels, and antioxidant enzyme and transcriptional factor Nrf2 activities. The results demonstrate that metformin disrupted GSIS in a concentration-dependent manner, lowered insulin content, and attenuated beta-cell metabolism. At high concentrations, metformin induced cell death and cell cycle arrest as well as increased ROS generation, consequently reducing GSH content. Although carbonylated protein content was elevated, indicating oxidative stress, the antioxidant enzyme and Nrf2 activities were not altered. In conclusion, our results show that metformin disrupts pancreatic beta-cell functionality but does not exert a putative antioxidant effect. It is important to note that the drug could potentially affect beta-cells, especially at high circulating levels.
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Affiliation(s)
- Maíra M R Valle
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.,Department of Physiology, Division of Biological Sciences, Federal University of Parana, Curitiba, Parana, Brazil
| | - Eloisa Aparecida Vilas-Boas
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.,Department of Physiology, Division of Biological Sciences, Federal University of Parana, Curitiba, Parana, Brazil
| | - Camila F Lucena
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.,Department of Physiology, Division of Biological Sciences, Federal University of Parana, Curitiba, Parana, Brazil
| | - Simone A Teixeira
- Department of Physiology, Division of Biological Sciences, Federal University of Parana, Curitiba, Parana, Brazil.,Department of Pharmacology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Marcelo N Muscara
- Department of Physiology, Division of Biological Sciences, Federal University of Parana, Curitiba, Parana, Brazil.,Department of Pharmacology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Angelo R Carpinelli
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.,Department of Physiology, Division of Biological Sciences, Federal University of Parana, Curitiba, Parana, Brazil
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8
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Post-Translational Modification and Subcellular Compartmentalization: Emerging Concepts on the Regulation and Physiopathological Relevance of RhoGTPases. Cells 2021; 10:cells10081990. [PMID: 34440759 PMCID: PMC8393718 DOI: 10.3390/cells10081990] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 07/31/2021] [Accepted: 08/02/2021] [Indexed: 12/26/2022] Open
Abstract
Cells and tissues are continuously exposed to both chemical and physical stimuli and dynamically adapt and respond to this variety of external cues to ensure cellular homeostasis, regulated development and tissue-specific differentiation. Alterations of these pathways promote disease progression-a prominent example being cancer. Rho GTPases are key regulators of the remodeling of cytoskeleton and cell membranes and their coordination and integration with different biological processes, including cell polarization and motility, as well as other signaling networks such as growth signaling and proliferation. Apart from the control of GTP-GDP cycling, Rho GTPase activity is spatially and temporally regulated by post-translation modifications (PTMs) and their assembly onto specific protein complexes, which determine their controlled activity at distinct cellular compartments. Although Rho GTPases were traditionally conceived as targeted from the cytosol to the plasma membrane to exert their activity, recent research demonstrates that active pools of different Rho GTPases also localize to endomembranes and the nucleus. In this review, we discuss how PTM-driven modulation of Rho GTPases provides a versatile mechanism for their compartmentalization and functional regulation. Understanding how the subcellular sorting of active small GTPase pools occurs and what its functional significance is could reveal novel therapeutic opportunities.
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He X, Gao F, Hou J, Li T, Tan J, Wang C, Liu X, Wang M, Liu H, Chen Y, Yu Z, Yang M. Metformin inhibits MAPK signaling and rescues pancreatic aquaporin 7 expression to induce insulin secretion in type 2 diabetes mellitus. J Biol Chem 2021; 297:101002. [PMID: 34303707 PMCID: PMC8374641 DOI: 10.1016/j.jbc.2021.101002] [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: 01/19/2021] [Revised: 07/15/2021] [Accepted: 07/21/2021] [Indexed: 02/07/2023] Open
Abstract
Metformin is the first-line antidiabetic agent for type 2 diabetes mellitus (T2DM) treatment. Although accumulated evidence has shed light on the consequences of metformin action, the precise mechanisms of its action, especially in the pancreas, are not fully understood. Aquaporin 7 (AQP7) acts as a critical regulator of intraislet glycerol content, which is necessary for insulin production and secretion. The aim of this study was to investigate the effects of different doses of metformin on AQP7 expression and explore the possible mechanism of its protective effects in the pancreatic islets. We used an in vivo model of high-fat diet in streptozocin-induced diabetic rats and an in vitro model of rat pancreatic β-cells (INS-1 cells) damaged by hyperglycemia and hyperlipidemia. Our data showed that AQP7 expression levels were decreased, whereas p38 and JNK mitogen-activated protein kinases (MAPKs) were activated in vivo and in vitro in response to hyperglycemia and hyperlipidemia. T2DM rats treated with metformin demonstrated a reduction in blood glucose levels and increased regeneration of pancreatic β-cells. In addition, metformin upregulated AQP7 expression as well as inhibited activation of p38 and JNK MAPKs both in vivo and in vitro. Overexpression of AQP7 increased glycerol influx into INS-1 cells, whereas inhibition of AQP7 reduced glycerol influx, thereby decreasing subsequent insulin secretion. Our findings demonstrate a new mechanism by which metformin suppresses the p38 and JNK pathways, thereby upregulating pancreatic AQP7 expression and promoting glycerol influx into pancreatic β-cells and subsequent insulin secretion in T2DM.
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Affiliation(s)
- Xueting He
- Department of Anatomy, College of Basic Medicine, Chongqing Medical University, Chongqing, People's Republic of China
| | - Fei Gao
- Department of Urology, The First Affiliated Hospital, Chongqing Medical University, Chongqing, People's Republic of China
| | - Jiaojiao Hou
- Department of Anatomy, College of Basic Medicine, Chongqing Medical University, Chongqing, People's Republic of China
| | - Tingjie Li
- Department of Anatomy, College of Basic Medicine, Chongqing Medical University, Chongqing, People's Republic of China
| | - Jiang Tan
- Department of Anatomy, College of Basic Medicine, Chongqing Medical University, Chongqing, People's Republic of China
| | - Chunyu Wang
- Department of Anatomy, College of Basic Medicine, Chongqing Medical University, Chongqing, People's Republic of China
| | - Xiaoyan Liu
- Department of Anatomy, College of Basic Medicine, Chongqing Medical University, Chongqing, People's Republic of China
| | - Maoqi Wang
- Department of Anatomy, College of Basic Medicine, Chongqing Medical University, Chongqing, People's Republic of China
| | - Hui Liu
- Department of Anatomy, College of Basic Medicine, Chongqing Medical University, Chongqing, People's Republic of China
| | - Yuqin Chen
- Institute of Neuroscience, College of Basic Medicine, Chongqing Medical University, Chongqing, People's Republic of China
| | - Zhuoyuan Yu
- Department of Urology, The First Affiliated Hospital, Chongqing Medical University, Chongqing, People's Republic of China
| | - Mei Yang
- Department of Anatomy, College of Basic Medicine, Chongqing Medical University, Chongqing, People's Republic of China.
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10
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Gendaszewska-Darmach E, Garstka MA, Błażewska KM. Targeting Small GTPases and Their Prenylation in Diabetes Mellitus. J Med Chem 2021; 64:9677-9710. [PMID: 34236862 PMCID: PMC8389838 DOI: 10.1021/acs.jmedchem.1c00410] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
![]()
A fundamental role
of pancreatic β-cells to maintain proper
blood glucose level is controlled by the Ras superfamily of small
GTPases that undergo post-translational modifications, including prenylation.
This covalent attachment with either a farnesyl or a geranylgeranyl
group controls their localization, activity, and protein–protein
interactions. Small GTPases are critical in maintaining glucose homeostasis
acting in the pancreas and metabolically active tissues such as skeletal
muscles, liver, or adipocytes. Hyperglycemia-induced upregulation
of small GTPases suggests that inhibition of these pathways deserves
to be considered as a potential therapeutic approach in treating T2D.
This Perspective presents how inhibition of various points in the
mevalonate pathway might affect protein prenylation and functioning
of diabetes-affected tissues and contribute to chronic inflammation
involved in diabetes mellitus (T2D) development. We also demonstrate
the currently available molecular tools to decipher the mechanisms
linking the mevalonate pathway’s enzymes and GTPases with diabetes.
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Affiliation(s)
- Edyta Gendaszewska-Darmach
- Institute of Molecular and Industrial Biotechnology, Faculty of Biotechnology and Food Sciences, Lodz University of Technology, Stefanowskiego Street 4/10, 90-924 Łódź, Poland
| | - Malgorzata A Garstka
- Core Research Laboratory, Department of Endocrinology, Department of Tumor and Immunology, Precision Medical Institute, Western China Science and Technology Innovation Port, School of Medicine, the Second Affiliated Hospital of Xi'an Jiaotong University, DaMingGong, Jian Qiang Road, Wei Yang district, Xi'an 710016, China
| | - Katarzyna M Błażewska
- Institute of Organic Chemistry, Faculty of Chemistry, Lodz University of Technology, Żeromskiego Street 116, 90-924 Łódź, Poland
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Veluthakal R, Thurmond DC. Emerging Roles of Small GTPases in Islet β-Cell Function. Cells 2021; 10:1503. [PMID: 34203728 PMCID: PMC8232272 DOI: 10.3390/cells10061503] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 06/08/2021] [Accepted: 06/08/2021] [Indexed: 12/16/2022] Open
Abstract
Several small guanosine triphosphatases (GTPases) from the Ras protein superfamily regulate glucose-stimulated insulin secretion in the pancreatic islet β-cell. The Rho family GTPases Cdc42 and Rac1 are primarily involved in relaying key signals in several cellular functions, including vesicle trafficking, plasma membrane homeostasis, and cytoskeletal dynamics. They orchestrate specific changes at each spatiotemporal region within the β-cell by coordinating with signal transducers, guanine nucleotide exchange factors (GEFs), GTPase-activating factors (GAPs), and their effectors. The Arf family of small GTPases is involved in vesicular trafficking (exocytosis and endocytosis) and actin cytoskeletal dynamics. Rab-GTPases regulate pre-exocytotic and late endocytic membrane trafficking events in β-cells. Several additional functions for small GTPases include regulating transcription factor activity and mitochondrial dynamics. Importantly, defects in several of these GTPases have been found associated with type 2 diabetes (T2D) etiology. The purpose of this review is to systematically denote the identities and molecular mechanistic steps in the glucose-stimulated insulin secretion pathway that leads to the normal release of insulin. We will also note newly identified defects in these GTPases and their corresponding regulatory factors (e.g., GDP dissociation inhibitors (GDIs), GEFs, and GAPs) in the pancreatic β-cells, which contribute to the dysregulation of metabolism and the development of T2D.
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Affiliation(s)
- Rajakrishnan Veluthakal
- Department of Molecular and Cellular Endocrinology, Arthur Riggs Diabetes & Metabolism Research Institute, City of Hope Beckman Research Institute, Duarte, CA 91010, USA
| | - Debbie C. Thurmond
- Department of Molecular and Cellular Endocrinology, Arthur Riggs Diabetes & Metabolism Research Institute, City of Hope Beckman Research Institute, Duarte, CA 91010, USA
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Kowluru A. Roles of GTP and Rho GTPases in pancreatic islet beta cell function and dysfunction. Small GTPases 2020; 12:323-335. [PMID: 32867592 DOI: 10.1080/21541248.2020.1815508] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
A growing body of evidence implicates requisite roles for GTP and its binding proteins (Rho GTPases) in the cascade of events leading to physiological insulin secretion from the islet beta cell. Interestingly, chronic exposure of these cells to hyperglycaemic conditions appears to result in sustained activation of specific Rho GTPases (e.g. Rac1) leading to significant alterations in cellular functions including defects in mitochondrial function and nuclear collapse culminating in beta cell demise. One of the objectives of this review is to highlight our current understanding of the regulatory roles of GTP and Rho GTPases in normal islet function (e.g. proliferation and insulin secretion) as well potential defects in these signalling molecules and metabolic pathways that could contribute islet beta cell dysfunction and loss of functional beta cell mass leading to the onset of diabetes. Potential knowledge gaps in this field and possible avenues for future research are also highlighted. ABBREVIATIONS ARNO: ADP-ribosylation factor nucleotide binding site opener; CML: carboxyl methylation; Epac: exchange protein directly activated by cAMP; ER stress: endoplasmic reticulum stress; FTase: farnesyltransferase; GAP: GTPase activating protein; GDI: GDP dissociation inhibitor; GEF: guanine nucleotide exchange factor; GGTase: geranylgeranyltransferase; GGpp: geranylgeranylpyrophosphate; GGPPS: geranylgeranyl pyrophosphate synthase; GSIS: glucose-stimulated insulin secretion; HGPRTase: hypoxanthine-guanine phosphoribosyltransferase; IMPDH: inosine monophosphate dehydrogenase; α-KIC: α-ketoisocaproic acid; MPA: mycophenolic acid; MVA: mevalonic acid; NDPK: nucleoside diphosphate kinase; NMPK: nucleoside monophosphate kinase; Nox2: phagocyte-like NADPH oxidase; PAK-I: p21-activated kinase-I; β-PIX: β-Pak-interacting exchange factor; PRMT: protein arginine methyltransferase; Rac1: ras-related C3 botulinum toxin substrate 1; Tiam1: T-cell lymphoma invasion and metastasis-inducing protein 1; Trx-1: thioredoxin-1; Vav2: vav guanine nucleotide exchange factor 2.
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Affiliation(s)
- Anjaneyulu Kowluru
- Biomedical Research Service, John D. Dingell VA Medical Center and Department of Pharmaceutical Sciences and Medicine, Wayne State University, Detroit, MI, USA
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13
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Kowluru A. Potential roles of PP2A-Rac1 signaling axis in pancreatic β-cell dysfunction under metabolic stress: Progress and promise. Biochem Pharmacol 2020; 180:114138. [PMID: 32634437 DOI: 10.1016/j.bcp.2020.114138] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 07/01/2020] [Accepted: 07/02/2020] [Indexed: 12/16/2022]
Abstract
Recent estimates by the International Diabetes Federation suggest that the incidence of diabetes soared to an all-time high of 463 million in 2019, and the federation predicts that by 2045 the number of individuals afflicted with this disease will increase to 700 million. Therefore, efforts to understand the pathophysiology of diabetes are critical for moving toward the development of novel therapeutic strategies for this disease. Several contributors (oxidative stress, endoplasmic reticulum stress and others) have been proposed for the onset of metabolic dysfunction and demise of the islet β-cell leading to the pathogenesis of diabetes. Existing experimental evidence revealed sustained activation of PP2A and Rac1 in pancreatic β-cells exposed to metabolic stress (diabetogenic) conditions. Evidence in a variety of cell types implicates modulatory roles for specific signaling proteins (α4, SET, nm23-H1, Pak1) in the functional regulation of PP2A and Rac1. In this Commentary, I overviewed potential cross-talk between PP2A and Rac1 signaling modules in the onset of metabolic dysregulation of the islet β-cell leading to impaired glucose-stimulated insulin secretion (GSIS), loss of β-cell mass and the onset of diabetes. Potential knowledge gaps and future directions in this fertile area of islet biology are also highlighted. It is hoped that this Commentary will provide a basis for future studies toward a better understanding of roles of PP2A-Rac1 signaling module in pancreatic β-cell dysfunction, and identification of therapeutic targets for the treatment of islet β-cell dysfunction in diabetes.
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Affiliation(s)
- Anjaneyulu Kowluru
- Biomedical Laboratory Research Service, John D. Dingell VA Medical Center and Departments of Pharmaceutical Sciences and Internal Medicine, Wayne State University, Detroit, MI 48201, USA.
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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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Damacharla D, Thamilselvan V, Zhang X, Mestareehi A, Yi Z, Kowluru A. Quantitative proteomics reveals novel interaction partners of Rac1 in pancreatic β-cells: Evidence for increased interaction with Rac1 under hyperglycemic conditions. Mol Cell Endocrinol 2019; 494:110489. [PMID: 31202817 PMCID: PMC6686664 DOI: 10.1016/j.mce.2019.110489] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 06/11/2019] [Accepted: 06/11/2019] [Indexed: 11/19/2022]
Abstract
Rac1, a small G protein, regulates physiological insulin secretion from the pancreatic β-cell. Interestingly, Rac1 has also been implicated in the onset of metabolic dysfunction of the β-cell under the duress of hyperglycemia (HG). This study is aimed at the identification of interaction partners of Rac1 in β-cells under basal and HG conditions. Using co-immunoprecipitation and UPLC-ESI-MS/MS, we identified 324 Rac1 interaction partners in INS-1832/13 cells, which represent the largest Rac1 interactome to date. Furthermore, we identified 27 interaction partners that exhibited increased association with Rac1 in β-cells exposed to HG. Western blotting (INS-1832/13 cells, rat islets and human islets) and co-immunoprecipitation (INS-1832/13 cells) further validated the identity of these Rac1 interaction partners including regulators of GPCR-G protein-effector coupling in the islet. These data form the basis for future investigations on contributory roles of these Rac1-specific signaling pathways in islet β-cell function in health and diabetes.
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Affiliation(s)
- Divyasri Damacharla
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, USA
| | - Vijayalakshmi Thamilselvan
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, USA
| | - Xiangmin Zhang
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, USA
| | - Aktham Mestareehi
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, USA
| | - Zhengping Yi
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, USA
| | - Anjaneyulu Kowluru
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, USA; Center for Translational Research in Diabetes, Biomedical Research Service, John D. Dingell VA Medical Center, Detroit, MI, 48201, USA.
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DiNicolantonio JJ, McCarty M. Autophagy-induced degradation of Notch1, achieved through intermittent fasting, may promote beta cell neogenesis: implications for reversal of type 2 diabetes. Open Heart 2019; 6:e001028. [PMID: 31218007 PMCID: PMC6546199 DOI: 10.1136/openhrt-2019-001028] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/06/2019] [Indexed: 02/06/2023] Open
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Kowluru A, Kowluru RA. RACking up ceramide-induced islet β-cell dysfunction. Biochem Pharmacol 2018; 154:161-169. [PMID: 29715450 DOI: 10.1016/j.bcp.2018.04.026] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Accepted: 04/27/2018] [Indexed: 12/20/2022]
Abstract
The International Diabetes Federation predicts that by 2045 the number of individuals afflicted with diabetes will increase to 629 million. Furthermore, ∼352 million individuals with impaired glucose tolerance are at increased risk for developing diabetes. Several mechanisms have been proposed for the onset of metabolic dysfunction and demise of the islet β-cell leading to the pathogenesis of diabetes. It is widely accepted that the onset of type 2 diabetes is due to an intricate interplay between genetic expression of the disease and a multitude of factors including increased oxidative and endoplasmic reticulum stress consequential to glucolipotoxicity and inflammation. Compelling experimental evidence from in vitro and in vivo studies implicates intracellular generation of ceramide (CER), a biologically-active sphingolipid, as a trigger in the onset of β-cell demise under above pathological conditions. Recent pharmacological and molecular biological evidence affirms regulatory roles for Ras-related C3 botulinum toxin substrate 1 (Rac1), a small G protein, in the islet β-cell function in health and diabetes. In this Commentary, we overviewed the emerging evidence implicating potential cross-talk between Rac1 and ceramide signaling pathways in the onset of metabolic dysregulation of the islet β-cell culminating in impaired physiological insulin secretion, loss of β-cell mass and the onset of diabetes. Further, we propose a model depicting contributory roles of defective protein lipidation (prenylation) pathway in the induction of metabolic defects in the β-cell under metabolic stress conditions. Potential avenues for the identification of novel therapeutic targets for the prevention/treatment of diabetes and its associated complications are highlighted.
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Affiliation(s)
- Anjaneyulu Kowluru
- Biomedical Research Service, John D. Dingell VA Medical Center, Wayne State University, Detroit, MI 48201, USA; Department of Pharmaceutical Sciences, Wayne State University, Detroit, MI 48201, USA.
| | - Renu A Kowluru
- Department of Ophthalmology and Anatomy and Cell Biology, Wayne State University, Detroit, MI 48201, USA
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