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Gleason N, Williams CL, Kowluru A. Novel regulatory roles of small G protein GDP dissociation stimulator (smgGDS) in insulin secretion from pancreatic β-cells. Mol Cell Endocrinol 2024; 580:112104. [PMID: 38013223 PMCID: PMC10842139 DOI: 10.1016/j.mce.2023.112104] [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: 10/09/2023] [Revised: 10/26/2023] [Accepted: 10/28/2023] [Indexed: 11/29/2023]
Abstract
Emerging evidence implicates novel roles for small G protein GDP dissociation stimulator (smgGDS) in G protein activation and subsequent targeting to relevant subcellular compartments for effector regulation. Given the well-established roles of small G proteins in insulin secretion, we undertook this investigation to determine the putative roles of smgGDS in insulin secretion. Immunoblotting studies revealed that both splice variants of smgGDS are expressed in human islets, rat islets and INS-1 832/13 cells. A significant inhibition (-52%) of glucose-stimulated insulin secretion (GSIS) was observed in INS-1 832/13 cells following siRNA-mediated depletion of smgGDS. In addition, insulin secretion elicited by a membrane depolarizing concentration of KCl (via increased calcium influx), forskolin (via increased cAMP generation) or IBMX (via inhibition of phosphodiesterase) was inhibited by -49%, -27%, and -28%, respectively. Subcellular distribution studies revealed no significant alterations in the abundance of smgGDS in the cytosolic and membrane fractions during the 45-min exposure of INS-1 832/13 cells to an insulinotropic concentration of glucose. Together, we present the first evidence of expression of smgGDS in human islets, rodent islets, and clonal β-cells. We also demonstrate novel regulatory roles of these proteins in insulin secretion derived from glucose metabolic events, including calcium- and cAMP-dependent signaling steps.
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Affiliation(s)
- Noah Gleason
- Research Service, John D. Dingell VA Medical Center, USA; Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, USA
| | - Carol L Williams
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Anjaneyulu Kowluru
- Research Service, John D. Dingell VA Medical Center, USA; Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, USA.
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2
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Moon DO. NADPH Dynamics: Linking Insulin Resistance and β-Cells Ferroptosis in Diabetes Mellitus. Int J Mol Sci 2023; 25:342. [PMID: 38203517 PMCID: PMC10779351 DOI: 10.3390/ijms25010342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 12/20/2023] [Accepted: 12/25/2023] [Indexed: 01/12/2024] Open
Abstract
This review offers an in-depth exploration of Nicotinamide Adenine Dinucleotide Phosphate (NADPH) in metabolic health. It delves into how NADPH affects insulin secretion, influences insulin resistance, and plays a role in ferroptosis. NADPH, a critical cofactor in cellular antioxidant systems and lipid synthesis, plays a central role in maintaining metabolic homeostasis. In adipocytes and skeletal muscle, NADPH influences the pathophysiology of insulin resistance, a hallmark of metabolic disorders such as type 2 diabetes and obesity. The review explores the mechanisms by which NADPH contributes to or mitigates insulin resistance, including its role in lipid and reactive oxygen species (ROS) metabolism. Parallelly, the paper investigates the dual nature of NADPH in the context of pancreatic β-cell health, particularly in its relation to ferroptosis, an iron-dependent form of programmed cell death. While NADPH's antioxidative properties are crucial for preventing oxidative damage in β-cells, its involvement in lipid metabolism can potentiate ferroptotic pathways under certain pathological conditions. This complex relationship underscores the delicate balance of NADPH homeostasis in pancreatic health and diabetes pathogenesis. By integrating findings from recent studies, this review aims to illuminate the nuanced roles of NADPH in different tissues and its potential as a therapeutic target. Understanding these dynamics offers vital insights into the development of more effective strategies for managing insulin resistance and preserving pancreatic β-cell function, thereby advancing the treatment of metabolic diseases.
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Affiliation(s)
- Dong-Oh Moon
- Department of Biology Education, Daegu University, 201 Daegudae-ro, Gyeongsan-si 38453, Gyeongsangbuk-do, Republic of Korea
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3
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Argaev-Frenkel L, Rosenzweig T. Redox Balance in Type 2 Diabetes: Therapeutic Potential and the Challenge of Antioxidant-Based Therapy. Antioxidants (Basel) 2023; 12:antiox12050994. [PMID: 37237860 DOI: 10.3390/antiox12050994] [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: 03/13/2023] [Revised: 04/19/2023] [Accepted: 04/24/2023] [Indexed: 05/28/2023] Open
Abstract
Oxidative stress is an important factor in the development of type 2 diabetes (T2D) and associated complications. Unfortunately, most clinical studies have failed to provide sufficient evidence regarding the benefits of antioxidants (AOXs) in treating this disease. Based on the known complexity of reactive oxygen species (ROS) functions in both the physiology and pathophysiology of glucose homeostasis, it is suggested that inappropriate dosing leads to the failure of AOXs in T2D treatment. To support this hypothesis, the role of oxidative stress in the pathophysiology of T2D is described, together with a summary of the evidence for the failure of AOXs in the management of diabetes. A comparison of preclinical and clinical studies indicates that suboptimal dosing of AOXs might explain the lack of benefits of AOXs. Conversely, the possibility that glycemic control might be adversely affected by excess AOXs is also considered, based on the role of ROS in insulin signaling. We suggest that AOX therapy should be given in a personalized manner according to the need, which is the presence and severity of oxidative stress. With the development of gold-standard biomarkers for oxidative stress, optimization of AOX therapy may be achieved to maximize the therapeutic potential of these agents.
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Affiliation(s)
| | - Tovit Rosenzweig
- Department of Molecular Biology, Ariel University, Ariel 4070000, Israel
- Adison School of Medicine, Ariel University, Ariel 4070000, Israel
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4
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Iron metabolism and ferroptosis in type 2 diabetes mellitus and complications: mechanisms and therapeutic opportunities. Cell Death Dis 2023; 14:186. [PMID: 36882414 PMCID: PMC9992652 DOI: 10.1038/s41419-023-05708-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 02/18/2023] [Accepted: 02/22/2023] [Indexed: 03/09/2023]
Abstract
The maintenance of iron homeostasis is essential for proper endocrine function. A growing body of evidence suggests that iron imbalance is a key factor in the development of several endocrine diseases. Nowadays, ferroptosis, an iron-dependent form of regulated cell death, has become increasingly recognized as an important process to mediate the pathogenesis and progression of type 2 diabetes mellitus (T2DM). It has been shown that ferroptosis in pancreas β cells leads to decreased insulin secretion; and ferroptosis in the liver, fat, and muscle induces insulin resistance. Understanding the mechanisms concerning the regulation of iron metabolism and ferroptosis in T2DM may lead to improved disease management. In this review, we summarized the connection between the metabolic pathways and molecular mechanisms of iron metabolism and ferroptosis in T2DM. Additionally, we discuss the potential targets and pathways concerning ferroptosis in treating T2DM and analysis the current limitations and future directions concerning these novel T2DM treatment targets.
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5
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Pecchillo Cimmino T, Ammendola R, Cattaneo F, Esposito G. NOX Dependent ROS Generation and Cell Metabolism. Int J Mol Sci 2023; 24:ijms24032086. [PMID: 36768405 PMCID: PMC9916913 DOI: 10.3390/ijms24032086] [Citation(s) in RCA: 28] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 01/17/2023] [Accepted: 01/18/2023] [Indexed: 01/21/2023] Open
Abstract
Reactive oxygen species (ROS) represent a group of high reactive molecules with dualistic natures since they can induce cytotoxicity or regulate cellular physiology. Among the ROS, the superoxide anion radical (O2·-) is a key redox signaling molecule prominently generated by the NADPH oxidase (NOX) enzyme family and by the mitochondrial electron transport chain. Notably, altered redox balance and deregulated redox signaling are recognized hallmarks of cancer and are involved in malignant progression and resistance to drugs treatment. Since oxidative stress and metabolism of cancer cells are strictly intertwined, in this review, we focus on the emerging roles of NOX enzymes as important modulators of metabolic reprogramming in cancer. The NOX family includes seven isoforms with different activation mechanisms, widely expressed in several tissues. In particular, we dissect the contribute of NOX1, NOX2, and NOX4 enzymes in the modulation of cellular metabolism and highlight their potential role as a new therapeutic target for tumor metabolism rewiring.
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Affiliation(s)
- Tiziana Pecchillo Cimmino
- Department of Molecular Medicine and Medical Biotechnology, School of Medicine, University of Naples Federico II, 80131 Naples, Italy
| | - Rosario Ammendola
- Department of Molecular Medicine and Medical Biotechnology, School of Medicine, University of Naples Federico II, 80131 Naples, Italy
| | - Fabio Cattaneo
- Department of Molecular Medicine and Medical Biotechnology, School of Medicine, University of Naples Federico II, 80131 Naples, Italy
- Correspondence: (F.C.); (G.E.)
| | - Gabriella Esposito
- Department of Molecular Medicine and Medical Biotechnology, School of Medicine, University of Naples Federico II, 80131 Naples, Italy
- CEINGE Advanced Biotechnologies Franco Salvatore S.c.a.r.l., 80131 Naples, Italy
- Correspondence: (F.C.); (G.E.)
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6
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Mukai E, Fujimoto S, Inagaki N. Role of Reactive Oxygen Species in Glucose Metabolism Disorder in Diabetic Pancreatic β-Cells. Biomolecules 2022; 12:biom12091228. [PMID: 36139067 PMCID: PMC9496160 DOI: 10.3390/biom12091228] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 08/28/2022] [Accepted: 08/31/2022] [Indexed: 11/18/2022] Open
Abstract
The dysfunction of pancreatic β-cells plays a central role in the onset and progression of type 2 diabetes mellitus (T2DM). Insulin secretory defects in β-cells are characterized by a selective impairment of glucose stimulation, and a reduction in glucose-induced ATP production, which is essential for insulin secretion. High glucose metabolism for insulin secretion generates reactive oxygen species (ROS) in mitochondria. In addition, the expression of antioxidant enzymes is very low in β-cells. Therefore, β-cells are easily exposed to oxidative stress. In islet studies using a nonobese T2DM animal model that exhibits selective impairment of glucose-induced insulin secretion (GSIS), quenching ROS generated by glucose stimulation and accumulated under glucose toxicity can improve impaired GSIS. Acute ROS generation and toxicity cause glucose metabolism disorders through different molecular mechanisms. Nuclear factor erythroid 2-related factor 2 (Nrf2), a transcription factor, is a master regulator of antioxidant defense and a potential therapeutic target in oxidative stress-related diseases, suggesting the possible involvement of Nrf2 in β-cell dysfunction caused by ROS. In this review, we describe the mechanisms of insulin secretory defects induced by oxidative stress in diabetic β-cells.
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Affiliation(s)
- Eri Mukai
- Medical Physiology and Metabolism Laboratory, Department of Biomedical Sciences, College of Life Sciences, Ritsumeikan University, Kusatsu 5258577, Japan
- Correspondence:
| | - Shimpei Fujimoto
- Department of Endocrinology, Metabolism, and Nephrology, Kochi Medical School, Kochi University, Kochi 7838505, Japan
| | - Nobuya Inagaki
- Department of Diabetes, Endocrinology and Nutrition, Graduate School of Medicine, Kyoto University, Kyoto 6068507, Japan
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7
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Azarova IE, Klyosova EY, Kolomoets II, Polonikov AV. Polymorphic Variants of the Neutrophil Cytosolic Factor 2 Gene: Associations with Susceptibility to Type 2 Diabetes Mellitus and Cardiovascular Autonomic Neuropathy. RUSS J GENET+ 2022. [DOI: 10.1134/s1022795422050039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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8
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Pang H, Li J, Li SJ. Role of the voltage-gated proton channel Hv1 in insulin secretion, glucose homeostasis, and obesity. J Physiol Biochem 2022; 78:593-601. [PMID: 35353324 DOI: 10.1007/s13105-022-00891-8] [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: 10/15/2020] [Accepted: 03/11/2022] [Indexed: 10/18/2022]
Abstract
Diabetes is characterized by an absolutely inadequate insulin secretion (type 1 diabetes mellitus) or a relative deficit in insulin secretion due to insulin resistance (type 2 diabetes mellitus), both of which result in elevated blood glucose. Understanding the molecular mechanisms underlying the pathophysiology of diabetes could lead to the development of new therapeutic approaches. The voltage-gated proton channel Hv1 is an ion channel with specific selectivity for protons, which is regulated by membrane potential and intracellular pH. Recently, our studies showed that Hv1 is expressed in β cells of the endocrine pancreas. Knockout of Hv1 reduces insulin secretion and results in hyperglycemia and glucose intolerance, but not insulin resistance. Furthermore, knockout of Hv1 leads to diet-induced obesity due to inflammation and hepatic steatosis. Increasing evidence suggests that Hv1 plays a pivotal role in glucose homeostasis and lipid metabolism. This review aims to summarize advances made so far in our understanding of the roles of Hv1 in the regulation of insulin secretion in β cells, glucose homeostasis, and obesity.
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Affiliation(s)
- Huimin Pang
- Department of Biophysics, School of Physics, The Key Laboratory of Bioactive Materials, Ministry of Education, Nankai University, 94 Weijin Road, Nankai District, Tianjin, 300071, People's Republic of China
| | - Jinwen Li
- Department of Biophysics, School of Physics, The Key Laboratory of Bioactive Materials, Ministry of Education, Nankai University, 94 Weijin Road, Nankai District, Tianjin, 300071, People's Republic of China
| | - Shu Jie Li
- Department of Biophysics, School of Physics, The Key Laboratory of Bioactive Materials, Ministry of Education, Nankai University, 94 Weijin Road, Nankai District, Tianjin, 300071, People's Republic of China.
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9
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Ahangarpour A, Oroojan AA. Myricitrin and Its Solid Lipid Nanoparticle Increase Insulin Secretion and Content of Isolated Islets from the Pancreas of Male Mice. BRAZ J PHARM SCI 2022. [DOI: 10.1590/s2175-97902022e20065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Akram Ahangarpour
- Ahvaz Jundishapur University of Medical Sciences, Iran; Ahvaz Jundishapur University of Medical Science, Iran
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10
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Vilas-Boas EA, Almeida DC, Roma LP, Ortis F, Carpinelli AR. Lipotoxicity and β-Cell Failure in Type 2 Diabetes: Oxidative Stress Linked to NADPH Oxidase and ER Stress. Cells 2021; 10:cells10123328. [PMID: 34943836 PMCID: PMC8699655 DOI: 10.3390/cells10123328] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 11/18/2021] [Accepted: 11/22/2021] [Indexed: 12/17/2022] Open
Abstract
A high caloric intake, rich in saturated fats, greatly contributes to the development of obesity, which is the leading risk factor for type 2 diabetes (T2D). A persistent caloric surplus increases plasma levels of fatty acids (FAs), especially saturated ones, which were shown to negatively impact pancreatic β-cell function and survival in a process called lipotoxicity. Lipotoxicity in β-cells activates different stress pathways, culminating in β-cells dysfunction and death. Among all stresses, endoplasmic reticulum (ER) stress and oxidative stress have been shown to be strongly correlated. One main source of oxidative stress in pancreatic β-cells appears to be the reactive oxygen species producer NADPH oxidase (NOX) enzyme, which has a role in the glucose-stimulated insulin secretion and in the β-cell demise during both T1 and T2D. In this review, we focus on the acute and chronic effects of FAs and the lipotoxicity-induced β-cell failure during T2D development, with special emphasis on the oxidative stress induced by NOX, the ER stress, and the crosstalk between NOX and ER stress.
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Affiliation(s)
- Eloisa Aparecida Vilas-Boas
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo 05508-000, Brazil
- Department of Biochemistry, Institute of Chemistry, University of São Paulo (USP), São Paulo 05508-900, Brazil
- Correspondence: (E.A.V.-B.); (A.R.C.); Tel.: +55-(11)-3091-7246 (A.R.C.)
| | - Davidson Correa Almeida
- Department of Cell and Developmental Biology, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo 05508-000, Brazil; (D.C.A.); (F.O.)
| | - Leticia Prates Roma
- Center for Human and Molecular Biology (ZHMB), Department of Biophysics, Saarland University, 66424 Homburg, Germany;
| | - Fernanda Ortis
- Department of Cell and Developmental Biology, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo 05508-000, Brazil; (D.C.A.); (F.O.)
| | - Angelo Rafael Carpinelli
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo 05508-000, Brazil
- Correspondence: (E.A.V.-B.); (A.R.C.); Tel.: +55-(11)-3091-7246 (A.R.C.)
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11
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Vilas-Boas EA, Carlein C, Nalbach L, Almeida DC, Ampofo E, Carpinelli AR, Roma LP, Ortis F. Early Cytokine-Induced Transient NOX2 Activity Is ER Stress-Dependent and Impacts β-Cell Function and Survival. Antioxidants (Basel) 2021; 10:antiox10081305. [PMID: 34439552 PMCID: PMC8389306 DOI: 10.3390/antiox10081305] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Revised: 08/13/2021] [Accepted: 08/15/2021] [Indexed: 01/23/2023] Open
Abstract
In type 1 diabetes (T1D) development, proinflammatory cytokines (PIC) released by immune cells lead to increased reactive oxygen species (ROS) production in β-cells. Nonetheless, the temporality of the events triggered and the role of different ROS sources remain unclear. Isolated islets from C57BL/6J wild-type (WT), NOX1 KO and NOX2 KO mice were exposed to a PIC combination. We show that cytokines increase O2•− production after 2 h in WT and NOX1 KO but not in NOX2 KO islets. Using transgenic mice constitutively expressing a genetically encoded compartment specific H2O2 sensor, we show, for the first time, a transient increase of cytosolic/nuclear H2O2 in islet cells between 4 and 5 h during cytokine exposure. The H2O2 increase coincides with the intracellular NAD(P)H decrease and is absent in NOX2 KO islets. NOX2 KO confers better glucose tolerance and protects against cytokine-induced islet secretory dysfunction and death. However, NOX2 absence does not counteract the cytokine effects in ER Ca2+ depletion, Store-Operated Calcium Entry (SOCE) increase and ER stress. Instead, the activation of ER stress precedes H2O2 production. As early NOX2-driven ROS production impacts β-cells’ function and survival during insulitis, NOX2 might be a potential target for designing therapies against early β-cell dysfunction in the context of T1D onset.
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Affiliation(s)
- Eloisa A. Vilas-Boas
- Center for Human and Molecular Biology (ZHMB), Department of Biophysics, Saarland University, 66424 Homburg, Germany; (E.A.V.-B.); (C.C.)
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo 05508-000, SP, Brazil;
| | - Christopher Carlein
- Center for Human and Molecular Biology (ZHMB), Department of Biophysics, Saarland University, 66424 Homburg, Germany; (E.A.V.-B.); (C.C.)
| | - Lisa Nalbach
- Institute for Clinical and Experimental Surgery, Saarland University, 66424 Homburg, Germany; (L.N.); (E.A.)
| | - Davidson C. Almeida
- Department of Cell and Developmental Biology, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo 05508-000, SP, Brazil;
| | - Emmanuel Ampofo
- Institute for Clinical and Experimental Surgery, Saarland University, 66424 Homburg, Germany; (L.N.); (E.A.)
| | - Angelo R. Carpinelli
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo 05508-000, SP, Brazil;
| | - Leticia P. Roma
- Center for Human and Molecular Biology (ZHMB), Department of Biophysics, Saarland University, 66424 Homburg, Germany; (E.A.V.-B.); (C.C.)
- Correspondence: (L.P.R.); (F.O.); Tel.: +06841-16-16240 (L.P.R.); +55-(11)-3091-0923 (F.O.); Fax: +06841-16-16302 (L.P.R.)
| | - Fernanda Ortis
- Department of Cell and Developmental Biology, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo 05508-000, SP, Brazil;
- Correspondence: (L.P.R.); (F.O.); Tel.: +06841-16-16240 (L.P.R.); +55-(11)-3091-0923 (F.O.); Fax: +06841-16-16302 (L.P.R.)
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12
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Gomes PRL, Vilas-Boas EA, Leite EDA, Munhoz AC, Lucena CF, Amaral FGD, Carpinelli AR, Cipolla-Neto J. Melatonin regulates maternal pancreatic remodeling and B-cell function during pregnancy and lactation. J Pineal Res 2021; 71:e12717. [PMID: 33460489 DOI: 10.1111/jpi.12717] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 12/16/2020] [Accepted: 01/07/2021] [Indexed: 01/23/2023]
Abstract
The endocrine pancreas of pregnant rats shows evident plasticity, which allows the morphological structures to return to the nonpregnant state right after delivery. Furthermore, it is well-known the role of melatonin in the maintenance of the endocrine pancreas and its tropism. Studies indicate increasing nocturnal serum concentrations of maternal melatonin during pregnancy in both humans and rodents. The present study investigated the role of melatonin on energy metabolism and in pancreatic function and remodeling during pregnancy and early lactation in rats. The results confirm that the absence of melatonin during pregnancy impairs glucose metabolism. In addition, there is a dysregulation in insulin secretion at various stages of the development of pregnancy and an apparent failure in the glucose-stimulated insulin secretion during the lactation period, evidencing the role of melatonin on the regulation of insulin secretion. This mechanism seems not to be dependent on the antioxidant effect of melatonin and probably dependent on MT2 receptors. We also observed changes in the mechanisms of death and cell proliferation at the end of pregnancy and beginning of lactation, crucial periods for pancreatic remodeling. The present observations strongly suggest that both functionality and remodeling of the endocrine pancreas are impaired in the absence of melatonin and its adequate replacement, mimicking the physiological increase seen during pregnancy, is able to reverse some of the damage observed. Thus, we conclude that pineal melatonin is important to metabolic adaptation to pregnancy and both the functionality of the beta cells and the remodeling of the pancreas during pregnancy and early lactation, ensuring the return to nonpregnancy conditions.
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Affiliation(s)
| | - Eloisa Aparecida Vilas-Boas
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, São Paulo, Brazil
| | - Eduardo de Almeida Leite
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, São Paulo, Brazil
| | - Ana Cláudia Munhoz
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, São Paulo, Brazil
| | - Camila Ferraz Lucena
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, São Paulo, Brazil
| | | | - Angelo Rafael Carpinelli
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, São Paulo, Brazil
| | - José Cipolla-Neto
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, São Paulo, Brazil
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13
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Elumalai S, Karunakaran U, Moon JS, Won KC. NADPH Oxidase (NOX) Targeting in Diabetes: A Special Emphasis on Pancreatic β-Cell Dysfunction. Cells 2021; 10:cells10071573. [PMID: 34206537 PMCID: PMC8307876 DOI: 10.3390/cells10071573] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Revised: 06/12/2021] [Accepted: 06/16/2021] [Indexed: 12/24/2022] Open
Abstract
In type 2 diabetes, metabolic stress has a negative impact on pancreatic β-cell function and survival (T2D). Although the pathogenesis of metabolic stress is complex, an imbalance in redox homeostasis causes abnormal tissue damage and β-cell death due to low endogenous antioxidant expression levels in β-cells. Under diabetogenic conditions, the susceptibility of β-cells to oxidative damage by NADPH oxidase has been related to contributing to β-cell dysfunction. Here, we consider recent insights into how the redox response becomes deregulated under diabetic conditions by NADPH oxidase, as well as the therapeutic benefits of NOX inhibitors, which may provide clues for understanding the pathomechanisms and developing strategies aimed at the treatment or prevention of metabolic stress associated with β-cell failure.
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Affiliation(s)
- Suma Elumalai
- Innovative Center for Aging Research, Yeungnam University Medical Center, Daegu 42415, Korea; (S.E.); (U.K.)
| | - Udayakumar Karunakaran
- Innovative Center for Aging Research, Yeungnam University Medical Center, Daegu 42415, Korea; (S.E.); (U.K.)
| | - Jun-Sung Moon
- Innovative Center for Aging Research, Yeungnam University Medical Center, Daegu 42415, Korea; (S.E.); (U.K.)
- Department of Internal Medicine, Yeungnam Universtiy College of Medicine, Daegu 42415, Korea
- Correspondence: (J.-S.M.); (K.-C.W.); Tel.: +82-53-620-3825 (J.-S.W.); +82-53-620-3846 (K.-C.W.)
| | - Kyu-Chang Won
- Innovative Center for Aging Research, Yeungnam University Medical Center, Daegu 42415, Korea; (S.E.); (U.K.)
- Department of Internal Medicine, Yeungnam Universtiy College of Medicine, Daegu 42415, Korea
- Correspondence: (J.-S.M.); (K.-C.W.); Tel.: +82-53-620-3825 (J.-S.W.); +82-53-620-3846 (K.-C.W.)
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14
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Nunes Marsiglio-Librais G, Aparecida Vilas-Boas E, Carlein C, Hoffmann MDA, Roma LP, Carpinelli AR. Evidence for NADPH oxidase activation by GPR40 in pancreatic β-cells. Redox Rep 2021; 25:41-50. [PMID: 32354273 PMCID: PMC7241480 DOI: 10.1080/13510002.2020.1757877] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Objective: Investigate the involvement of the fatty acids receptor GPR40 in the assembly and activation of NADPH oxidase and the implications on pancreatic β-cell function. Methods: BRIN-BD11 β-cells were exposed to GPR40 agonist (GW9508) or linoleic acid in different glucose concentrations. Superoxide and H2O2 were analyzed, respectively, by DHE fluorescence and by fluorescence of the H2O2 sensor, roGFP2-Orp1. Protein contents of p47phox in plasma membrane and cytosol were analyzed by western blot. NADPH oxidase role was evaluated by p22phox siRNA or by pharmacological inhibition with VAS2870. NOX2 KO islets were used to measure total cytosolic calcium and insulin secretion. Results: GW9508 and linoleic acid increased superoxide and H2O2 contents at 5.6 and 8.3 mM of glucose. In addition, in 5.6 mM, but not at 16.7 mM of glucose, activation of GPR40 led to the translocation of p47phox to the plasma membrane. Knockdown of p22phox abolished the increase in superoxide after GW9508 and linoleic acid. No differences in insulin secretion were found between wild type and NOX2 KO islets treated with GW9508 or linoleic acid. Discussion: We report for the first time that acute activation of GPR40 leads to NADPH oxidase activation in pancreatic β-cells, without impact on insulin secretion.
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Affiliation(s)
| | - Eloisa Aparecida Vilas-Boas
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo, Brazil.,Department of Biophysics, Center for Human and Molecular Biology, CIPMM, Saarland University, Homburg/Saar, Germany
| | - Christopher Carlein
- Department of Biophysics, Center for Human and Molecular Biology, CIPMM, Saarland University, Homburg/Saar, Germany
| | | | - Leticia Prates Roma
- Department of Biophysics, Center for Human and Molecular Biology, CIPMM, Saarland University, Homburg/Saar, Germany
| | - Angelo Rafael Carpinelli
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo (USP), São Paulo, Brazil
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15
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Ježek P, Holendová B, Jabůrek M, Tauber J, Dlasková A, Plecitá-Hlavatá L. The Pancreatic β-Cell: The Perfect Redox System. Antioxidants (Basel) 2021; 10:antiox10020197. [PMID: 33572903 PMCID: PMC7912581 DOI: 10.3390/antiox10020197] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 01/20/2021] [Accepted: 01/25/2021] [Indexed: 12/12/2022] Open
Abstract
Pancreatic β-cell insulin secretion, which responds to various secretagogues and hormonal regulations, is reviewed here, emphasizing the fundamental redox signaling by NADPH oxidase 4- (NOX4-) mediated H2O2 production for glucose-stimulated insulin secretion (GSIS). There is a logical summation that integrates both metabolic plus redox homeostasis because the ATP-sensitive K+ channel (KATP) can only be closed when both ATP and H2O2 are elevated. Otherwise ATP would block KATP, while H2O2 would activate any of the redox-sensitive nonspecific calcium channels (NSCCs), such as TRPM2. Notably, a 100%-closed KATP ensemble is insufficient to reach the -50 mV threshold plasma membrane depolarization required for the activation of voltage-dependent Ca2+ channels. Open synergic NSCCs or Cl- channels have to act simultaneously to reach this threshold. The resulting intermittent cytosolic Ca2+-increases lead to the pulsatile exocytosis of insulin granule vesicles (IGVs). The incretin (e.g., GLP-1) amplification of GSIS stems from receptor signaling leading to activating the phosphorylation of TRPM channels and effects on other channels to intensify integral Ca2+-influx (fortified by endoplasmic reticulum Ca2+). ATP plus H2O2 are also required for branched-chain ketoacids (BCKAs); and partly for fatty acids (FAs) to secrete insulin, while BCKA or FA β-oxidation provide redox signaling from mitochondria, which proceeds by H2O2 diffusion or hypothetical SH relay via peroxiredoxin "redox kiss" to target proteins.
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16
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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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17
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Rizzo G. The Antioxidant Role of Soy and Soy Foods in Human Health. Antioxidants (Basel) 2020; 9:antiox9070635. [PMID: 32708394 PMCID: PMC7402135 DOI: 10.3390/antiox9070635] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 07/08/2020] [Accepted: 07/16/2020] [Indexed: 02/07/2023] Open
Abstract
Oxidative stress seems to play a role in many chronic diseases, such as cardiovascular diseases, diabetes, and some cancers. Research is always looking for effective approaches in the prevention and treatment of these pathologies with safe strategies. Given the central role of nutrition, the identification of beneficial healthy foods can be the best key to having a safe and at the same time effective approach. Soy has always aroused great scientific interest but often this attention is galvanized by the interaction with estrogen receptors and related consequences on health. However, soy, soy foods, and soy bioactive substances seem to have antioxidant properties, suggesting their role in quenching reactive oxygen species, although it was frequently mentioned but not studied in depth. The purpose of this review is to summarize the scientific evidence of the antioxidant properties of soy by identifying the human clinical trials available in the literature. A total of 58 manuscripts were individuated through the literature search for the final synthesis. Soy bioactive substances involved in redox processes appear to be multiple and their use seems promising. Other larger clinical trials with adequate standardization and adequate choice of biomarkers will fill the gap currently existing on the suggestive role of soy in antioxidant mechanisms.
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Affiliation(s)
- Gianluca Rizzo
- Independent Researcher, Via Venezuela 66, 98121 Messina, Italy
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18
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Leguina-Ruzzi A, Vodičková A, Holendová B, Pavluch V, Tauber J, Engstová H, Dlasková A, Ježek P. Glucose-Induced Expression of DAPIT in Pancreatic β-Cells. Biomolecules 2020; 10:biom10071026. [PMID: 32664368 PMCID: PMC7408392 DOI: 10.3390/biom10071026] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 07/07/2020] [Accepted: 07/08/2020] [Indexed: 12/14/2022] Open
Abstract
Transcript levels for selected ATP synthase membrane FO-subunits-including DAPIT-in INS-1E cells were found to be sensitive to lowering glucose down from 11 mM, in which these cells are routinely cultured. Depending on conditions, the diminished mRNA levels recovered when glucose was restored to 11 mM; or were elevated during further 120 min incubations with 20-mM glucose. Asking whether DAPIT expression may be elevated by hyperglycemia in vivo, we studied mice with hyaluronic acid implants delivering glucose for up to 14 days. Such continuous two-week glucose stimulations in mice increased DAPIT mRNA by >5-fold in isolated pancreatic islets (ATP synthase F1α mRNA by 1.5-fold). In INS-1E cells, the glucose-induced ATP increment vanished with DAPIT silencing (6% of ATP rise), likewise a portion of the mtDNA-copy number increment. With 20 and 11-mM glucose the phosphorylating/non-phosphorylating respiration rate ratio diminished to ~70% and 96%, respectively, upon DAPIT silencing, whereas net GSIS rates accounted for 80% and 90% in USMG5/DAPIT-deficient cells. Consequently, the sufficient DAPIT expression and complete ATP synthase assembly is required for maximum ATP synthesis and mitochondrial biogenesis, but not for insulin secretion as such. Elevated DAPIT expression at high glucose further increases the ATP synthesis efficiency.
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19
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Plecitá-Hlavatá L, Jabůrek M, Holendová B, Tauber J, Pavluch V, Berková Z, Cahová M, Schröder K, Brandes RP, Siemen D, Ježek P. Glucose-Stimulated Insulin Secretion Fundamentally Requires H 2O 2 Signaling by NADPH Oxidase 4. Diabetes 2020; 69:1341-1354. [PMID: 32245800 DOI: 10.2337/db19-1130] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 03/30/2020] [Indexed: 11/13/2022]
Abstract
NADPH facilitates glucose-stimulated insulin secretion (GSIS) in pancreatic islets (PIs) of β-cells through an as yet unknown mechanism. We found NADPH oxidase isoform 4 (NOX4) to be the main producer of cytosolic H2O2, which is essential for GSIS; an increase in ATP alone was insufficient for GSIS. The fast GSIS phase was absent from PIs from NOX4-null, β-cell-specific knockout mice (NOX4βKO) (though not from NOX2 knockout mice) and from NOX4-silenced or catalase-overexpressing INS-1E cells. Lentiviral NOX4 overexpression or H2O2 rescued GSIS in PIs from NOX4βKO mice. NOX4 silencing suppressed Ca2+ oscillations, and the patch-clamped KATP channel opened more frequently when glucose was high. Mitochondrial H2O2, decreasing upon GSIS, provided alternative redox signaling when 2-oxo-isocaproate or fatty acid oxidation formed superoxides through electron-transfer flavoprotein:Q-oxidoreductase. Unlike GSIS, such insulin secretion was blocked with mitochondrial antioxidant SkQ1. Both NOX4 knockout and NOX4βKO mice exhibited impaired glucose tolerance and peripheral insulin resistance. Thus, the redox signaling previously suggested to cause β-cells to self-check hypothetically induces insulin resistance when it is absent. In conclusion, increases in ATP and H2O2 constitute an essential signal that switches on insulin exocytosis for glucose and branched-chain oxoacids as secretagogues (it does so partially for fatty acids). Redox signaling could be impaired by cytosolic antioxidants; hence, those targeting mitochondria should be preferred for clinical applications to treat (pre)diabetes at any stage.
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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
| | - Martin Jabůrek
- 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
| | - Vojtěch Pavluch
- Department of Mitochondrial Physiology, No. 75, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Zuzana Berková
- Institute of Clinical and Experimental Medicine, Prague, Czech Republic
| | - Monika Cahová
- Institute of Clinical and Experimental Medicine, Prague, Czech Republic
| | - Katrin Schröder
- Institut für Kardiovaskuläre Physiologie, Goethe-Universität, Frankfurt, Germany
| | - Ralf P Brandes
- Institut für Kardiovaskuläre Physiologie, Goethe-Universität, Frankfurt, Germany
| | - Detlef Siemen
- Klinik für Neurologie, Universität Magdeburg, Magdeburg, Germany
| | - Petr Ježek
- Department of Mitochondrial Physiology, No. 75, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
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20
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Bouzakri K, Veyrat-Durebex C, Holterman C, Arous C, Barbieux C, Bosco D, Altirriba J, Alibashe M, Tournier BB, Gunton JE, Mouche S, Bietiger W, Forterre A, Berney T, Pinget M, Christofori G, Kennedy C, Szanto I. Beta-Cell-Specific Expression of Nicotinamide Adenine Dinucleotide Phosphate Oxidase 5 Aggravates High-Fat Diet-Induced Impairment of Islet Insulin Secretion in Mice. Antioxid Redox Signal 2020; 32:618-635. [PMID: 31931619 DOI: 10.1089/ars.2018.7579] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Aims: Nicotinamide adenine dinucleotide phosphate oxidases (NOX-es) produce reactive oxygen species and modulate β-cell insulin secretion. Islets of type 2 diabetic subjects present elevated expression of NOX5. Here, we sought to characterize regulation of NOX5 expression in human islets in vitro and to uncover the relevance of NOX5 in islet function in vivo using a novel mouse model expressing NOX5 in doxycycline-inducible, β-cell-specific manner (RIP/rtTA/NOX5 mice). Results:In situ hybridization and immunohistochemistry employed on pancreatic sections demonstrated NOX5 messenger ribonucleic acid (mRNA) and protein expressions in human islets. In cultures of dispersed islets, NOX5 protein was observed in somatostatin-positive (δ) cells in basal (2.8 mM glucose) conditions. Small interfering ribonucleic acid (siRNA)-mediated knockdown of NOX5 in human islets cultured in basal glucose concentrations resulted in diminished glucose-induced insulin secretion (GIIS) in vitro. However, when islets were preincubated in high (16.7 mM) glucose media for 12 h, NOX5 appeared also in insulin-positive (β) cells. In vivo, mice with β-cell NOX5 expression developed aggravated impairment of GIIS compared with control mice when challenged with 14 weeks of high-fat diet. Similarly, in vitro palmitate preincubation resulted in more severe reduction of insulin release in islets of RIP/rtTA/NOX5 mice compared with their control littermates. Decreased insulin secretion was most distinct in response to theophylline stimulation, suggesting impaired cyclic adenosine monophosphate (cAMP)-mediated signaling due to increased phosphodiesterase activation. Innovation and Conclusions: Our data provide the first insight into the complex regulation and function of NOX5 in islets implying an important role for NOX5 in δ-cell-mediated intraislet crosstalk in physiological circumstances but also identifying it as an aggravating factor in β-cell failure in diabetic conditions.
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Affiliation(s)
- Karim Bouzakri
- Department of Genetic Medicine and Development, University of Geneva, Geneva, Switzerland.,Centre Européen d'Etude du Diabète, Strasbourg, France
| | | | - Chet Holterman
- Division of Nephrology, Department of Medicine, Kidney Research Centre, Ottawa Hospital Research Institute, Ottawa, Canada
| | - Caroline Arous
- Department of Genetic Medicine and Development, University of Geneva, Geneva, Switzerland.,Department of Cellular Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - Charlotte Barbieux
- Cell Isolation and Transplantation Center, Department of Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | - Domenico Bosco
- Cell Isolation and Transplantation Center, Department of Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | - Jordi Altirriba
- Laboratory of Metabolism, Department of Internal Medicine, Geneva University Hospitals, Geneva, Switzerland
| | - Mohamed Alibashe
- Cell Isolation and Transplantation Center, Department of Surgery, Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | - Benjamin B Tournier
- Vulnerability Biomarkers Unit, Division of General Psychiatry, Department of Psychiatry, University Hospitals of Geneva, Geneva, Switzerland
| | - Jenny E Gunton
- Centre for Diabetes, Obesity and Endocrinology, Westmead Millennium Institute, The University of Sydney, Sydney, Australia.,Diabetes and Transcription Factors Group, Garvan Institute of Medical Research, Sydney, Australia
| | - Sarah Mouche
- Department of Cellular Physiology and Metabolism, University of Geneva, Geneva, Switzerland.,Department of Internal Medicine, Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | | | | | - Thierry Berney
- Division of Transplantation, Department of Surgery, University Hospitals of Geneva, Geneva, Switzerland
| | - Michel Pinget
- Centre Européen d'Etude du Diabète, Strasbourg, France
| | | | - Christopher Kennedy
- Division of Nephrology, Department of Medicine, Kidney Research Centre, Ottawa Hospital Research Institute, Ottawa, Canada
| | - Ildiko Szanto
- Department of Internal Medicine, Geneva University Hospitals and University of Geneva, Geneva, Switzerland.,Diabetes Center of the Faculty of Medicine at the University of Geneva, Geneva, Switzerland
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21
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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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22
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Basmaeil Y, Rashid MA, Khatlani T, AlShabibi M, Bahattab E, Abdullah ML, Abomaray F, Kalionis B, Massoudi S, Abumaree M. Preconditioning of Human Decidua Basalis Mesenchymal Stem/Stromal Cells with Glucose Increased Their Engraftment and Anti-diabetic Properties. Tissue Eng Regen Med 2020; 17:209-222. [PMID: 32077075 PMCID: PMC7105536 DOI: 10.1007/s13770-020-00239-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 11/10/2019] [Accepted: 01/06/2020] [Indexed: 12/19/2022] Open
Abstract
Background: Mesenchymal stem/stromal cells (MSCs) from the decidua basalis (DBMSCs) of the human placenta have important functions that make them potential candidates for cellular therapy. Previously, we showed that DBMSC functions do not change significantly in a high oxidative stress environment, which was induced by hydrogen peroxide (H2O2) and immune cells. Here, we studied the consequences of glucose, another oxidative stress inducer, on the phenotypic and functional changes in DBMSCs. Methods: DBMSCs were exposed to a high level of glucose, and its effect on DBMSC phenotypic and functional properties was determined. DBMSC expression of oxidative stress and immune molecules after exposure to glucose were also identified. Results: Conditioning of DBMSCs with glucose improved their adhesion and invasion. Glucose also increased DBMSC expression of genes with survival, proliferation, migration, invasion, anti-inflammatory, anti-chemoattractant and antimicrobial properties. In addition, DBMSC expression of B7H4, an inhibitor of T cell proliferation was also enhanced by glucose. Interestingly, glucose modulated DBMSC expression of genes involved in insulin secretion and prevention of diabetes. Conclusion: These data show the potentially beneficial effects of glucose on DBMSC functions. Preconditioning of DBMSCs with glucose may therefore be a rational strategy for increasing their therapeutic potential by enhancing their engraftment efficiency. In addition, glucose may program DBMSCs into insulin producing cells with ability to counteract inflammation and infection associated with diabetes. However, future in vitro and in vivo studies are essential to investigate the findings of this study further. Electronic supplementary material The online version of this article (10.1007/s13770-020-00239-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yasser Basmaeil
- Stem Cells and Regenerative Medicine Department, King Abdullah International Medical Research Center, King Abdulaziz Medical City, Ministry of National Guard Health Affairs, Mail Code 1515, P.O. Box 22490, Riyadh, 11426, Kingdom of Saudi Arabia.
| | - Manar Al Rashid
- Stem Cells and Regenerative Medicine Department, King Abdullah International Medical Research Center, King Abdulaziz Medical City, Ministry of National Guard Health Affairs, Mail Code 1515, P.O. Box 22490, Riyadh, 11426, Kingdom of Saudi Arabia
| | - Tanvir Khatlani
- Stem Cells and Regenerative Medicine Department, King Abdullah International Medical Research Center, King Abdulaziz Medical City, Ministry of National Guard Health Affairs, Mail Code 1515, P.O. Box 22490, Riyadh, 11426, Kingdom of Saudi Arabia
| | - Manal AlShabibi
- National Center for Stem Cell Technology, Life Sciences and Environment Research Institute, King Abdulaziz City for Science and Technology, P.O Box 6086, Riyadh, 11442, Kingdom of Saudi Arabia
| | - Eman Bahattab
- National Center for Stem Cell Technology, Life Sciences and Environment Research Institute, King Abdulaziz City for Science and Technology, P.O Box 6086, Riyadh, 11442, Kingdom of Saudi Arabia
| | - Meshan L Abdullah
- Experimental Medicine, King Abdullah International Medical Research Center MNG-HA, Ali Al Arini, Ar Rimayah, Riyadh, 11481, Kingdom of Saudi Arabia
| | - Fawaz Abomaray
- Division of Obstetrics and Gynecology, Department of Clinical Science, Intervention and Technology, Karolinska Institutet, 14186, Stockholm, Sweden
| | - Bill Kalionis
- Department of Maternal-Fetal Medicine, Pregnancy Research Centre and University of Melbourne, Parkville, VIC, 3010, Australia.,Department of Obstetrics and Gynaecology, Royal Women's Hospital, 20 Flemington Rd, Parkville, VIC, 3052, Australia
| | - Safia Massoudi
- Department of Forensic Biology, College of Forensic Sciences, Naif Arab University for Security Sciences, Khurais Rd, Ar Rimayah, Riyadh, 14812, Kingdom of Saudi Arabia
| | - Mohammad Abumaree
- Stem Cells and Regenerative Medicine Department, King Abdullah International Medical Research Center, King Abdulaziz Medical City, Ministry of National Guard Health Affairs, Mail Code 1515, P.O. Box 22490, Riyadh, 11426, Kingdom of Saudi Arabia.,College of Science and Health Professions, King Saud Bin Abdulaziz University for Health Sciences, King Abdulaziz Medical City, Ministry of National Guard Health Affairs, Mail Code 3124, P.O. Box 3660, Riyadh, 11481, Kingdom of Saudi Arabia
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23
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Newsholme P, Keane KN, Carlessi R, Cruzat V. Oxidative stress pathways in pancreatic β-cells and insulin-sensitive cells and tissues: importance to cell metabolism, function, and dysfunction. Am J Physiol Cell Physiol 2019; 317:C420-C433. [PMID: 31216193 DOI: 10.1152/ajpcell.00141.2019] [Citation(s) in RCA: 97] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
It is now accepted that nutrient abundance in the blood, especially glucose, leads to the generation of reactive oxygen species (ROS), ultimately leading to increased oxidative stress in a variety of tissues. In the absence of an appropriate compensatory response from antioxidant mechanisms, the cell, or indeed the tissue, becomes overwhelmed by oxidative stress, leading to the activation of intracellular stress-associated pathways. Activation of the same or similar pathways also appears to play a role in mediating insulin resistance, impaired insulin secretion, and late diabetic complications. The ability of antioxidants to protect against the oxidative stress induced by hyperglycemia and elevated free fatty acid (FFA) levels in vitro suggests a causative role of oxidative stress in mediating the latter clinical conditions. In this review, we describe common biochemical processes associated with oxidative stress driven by hyperglycemia and/or elevated FFA and the resulting clinical outcomes: β-cell dysfunction and peripheral tissue insulin resistance.
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Affiliation(s)
- Philip Newsholme
- School of Pharmacy and Biomedical Sciences, and Curtin Health Innovation Research Institute, Curtin University, Perth, Western Australia, Australia
| | - Kevin N Keane
- School of Pharmacy and Biomedical Sciences, and Curtin Health Innovation Research Institute, Curtin University, Perth, Western Australia, Australia
| | - Rodrigo Carlessi
- School of Pharmacy and Biomedical Sciences, and Curtin Health Innovation Research Institute, Curtin University, Perth, Western Australia, Australia
| | - Vinicius Cruzat
- Faculty of Health, Torrens University Australia, Melbourne, Victoria, Australia
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24
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Wang X, Gao YT, Jiang D, Wang Y, Du H, Lv J, Li SJ. Hv1-deficiency protects β cells from glucotoxicity through regulation of NOX4 level. Biochem Biophys Res Commun 2019; 513:434-438. [PMID: 30967259 DOI: 10.1016/j.bbrc.2019.03.195] [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: 03/24/2019] [Accepted: 03/29/2019] [Indexed: 11/27/2022]
Abstract
High glucose (HG)-induced oxidative stress contributes to the dysfunction of pancreatic β cells in diabetes. The voltage-gated proton channel Hv1 has been proposed to support reactive oxygen species (ROS) production during respiratory bursts. However, the effect of Hv1 on glucotoxicity in pancreatic β cells is not clear yet. In this study, we examined the protective effects of Hv1-deficiency in HG cultured β cells. Following 48 h of treatment with 30 mM high glucose, Hv1 KO β cells showed higher cell viability, lower cell apoptosis and a more stable insulin gene expression level compared to WT β cells. In both control and HG cultured β cells, deficiency of Hv1 decreased the glucose- and PMA-induced ROS production. Finally, HG incubation led to NOX4 upregulation in WT β cells, which could be inhibited by HV1 deficiency. In conclusion, Hv1-deficiency prevents the HG treatment-induced NOX4 upregulation and protects β cells from glucotoxicity.
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Affiliation(s)
- Xudong Wang
- Department of Biophysics, School of Physics Science, The Key Laboratory of Bioactive Materials, Ministry of Education, Nankai University, Tianjin, 300071, PR China
| | - Ying-Tang Gao
- Key Laboratory of Artificial Cell, Third Central Clinical College of Tianjin Medical University, Tianjin, 300170, PR China
| | - Dan Jiang
- Department of Biophysics, School of Physics Science, The Key Laboratory of Bioactive Materials, Ministry of Education, Nankai University, Tianjin, 300071, PR China
| | - Yuzhou Wang
- Laboratory Animal Center, College of Life Sciences, Nankai University, Tianjin, 300071, PR China
| | - Hongyan Du
- Department of Biophysics, School of Physics Science, The Key Laboratory of Bioactive Materials, Ministry of Education, Nankai University, Tianjin, 300071, PR China
| | - Jili Lv
- Department of Biophysics, School of Physics Science, The Key Laboratory of Bioactive Materials, Ministry of Education, Nankai University, Tianjin, 300071, PR China
| | - Shu Jie Li
- Department of Biophysics, School of Physics Science, The Key Laboratory of Bioactive Materials, Ministry of Education, Nankai University, Tianjin, 300071, PR China.
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Elksnis A, Martinell M, Eriksson O, Espes D. Heterogeneity of Metabolic Defects in Type 2 Diabetes and Its Relation to Reactive Oxygen Species and Alterations in Beta-Cell Mass. Front Physiol 2019; 10:107. [PMID: 30837889 PMCID: PMC6383038 DOI: 10.3389/fphys.2019.00107] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 01/28/2019] [Indexed: 12/21/2022] Open
Abstract
Type 2 diabetes (T2D) is a complex and heterogeneous disease which affects millions of people worldwide. The classification of diabetes is at an interesting turning point and there have been several recent reports on sub-classification of T2D based on phenotypical and metabolic characteristics. An important, and perhaps so far underestimated, factor in the pathophysiology of T2D is the role of oxidative stress and reactive oxygen species (ROS). There are multiple pathways for excessive ROS formation in T2D and in addition, beta-cells have an inherent deficit in the capacity to cope with oxidative stress. ROS formation could be causal, but also contribute to a large number of the metabolic defects in T2D, including beta-cell dysfunction and loss. Currently, our knowledge on beta-cell mass is limited to autopsy studies and based on comparisons with healthy controls. The combined evidence suggests that beta-cell mass is unaltered at onset of T2D but that it declines progressively. In order to better understand the pathophysiology of T2D, to identify and evaluate novel treatments, there is a need for in vivo techniques able to quantify beta-cell mass. Positron emission tomography holds great potential for this purpose and can in addition map metabolic defects, including ROS activity, in specific tissue compartments. In this review, we highlight the different phenotypical features of T2D and how metabolic defects impact oxidative stress and ROS formation. In addition, we review the literature on alterations of beta-cell mass in T2D and discuss potential techniques to assess beta-cell mass and metabolic defects in vivo.
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Affiliation(s)
- Andris Elksnis
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Mats Martinell
- Department of Public Health and Caring Sciences, Uppsala University, Uppsala, Sweden
| | - Olof Eriksson
- Science for Life Laboratory, Department of Medicinal Chemistry, Uppsala University, Uppsala, Sweden
| | - Daniel Espes
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden.,Department of Medical Sciences, Uppsala University, Uppsala, Sweden
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Saleh A, Anwar MM, Zayed AE, Ezz Eldeen MES, Afifi G, Alnashiri HM, Gomaa AMS, Abd-Elkareem M, Abou-Elhamd AS, Shaheen ES, Mohamed GA, Hetta HF, Kotb AM. Impact of Ginkgo biloba extract and magnetized water on the survival rate and functional capabilities of pancreatic β-cells in type 2 diabetic rat model. Diabetes Metab Syndr Obes 2019; 12:1339-1347. [PMID: 31496771 PMCID: PMC6689767 DOI: 10.2147/dmso.s209856] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2019] [Accepted: 07/16/2019] [Indexed: 12/15/2022] Open
Abstract
INTRODUCTION Type 2 diabetes (T2D) is a widely distributed disease that affects large population worldwide. This study aimed to verify the role of Ginkgo biloba (GB) extract and magnetized water (MW) on the survival rate and functional capabilities of pancreatic β-cells in type 2 diabetic rats. MATERIALS AND METHODS T2D was induced by feeding the rats on a high-fat diet (20% fat, 45% carbohydrate, 22% protein) for eight weeks followed by intra-peritoneal injection of a single low dose of streptozotocin (25mg/Kg). Forty rats were randomly assigned to four groups (n=10 rats) as follows: non treated control and three diabetic groups. One diabetic group served as a positive control (diabetic), while the other two groups were orally administered with water extract of GB leaves (0.11 g/kg/day) and MW (600 gauss) for four weeks, respectively. RESULTS The β-cell mass and insulin expression in these cells increased markedly after both treatments, particularly in GB treated group. In addition, the immune-expression of the two antioxidant enzymes; glutathione and superoxide dismutase 2 (SOD2) in the pancreatic tissue demonstrated a down-regulation in GB and MW treated groups as compared with the diabetic group. CONCLUSION A four-week treatment of GB and MW protected pancreatic β-cell cells and improved their insulin expression and antioxidant status in type 2 diabetic rats.
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Affiliation(s)
- Ahmed Saleh
- Department of Physics, Faculty of Science, Jazan University, Jazan, KSA
- Exploratory Center of Science and Technology
, Cairo, Egypt
| | - Mamdouh M Anwar
- Department of Pharmacology, Faculty of Pharmacy, Jazan University, Jazan, KSA
- Medical Physiology Department, Faculty of Medicine, Assiut University, Assiut, Egypt
| | - Ahmed E Zayed
- Department of Biology, Faculty of Science, Jazan University, Jazan, KSA
- Department of Anatomy and Histology, Faculty of Veterinary Medicine, Assiut University, Egypt
| | - Manal El Sayed Ezz Eldeen
- Endocrine Unit, Department of Internal Medicine, Faculty of Medicine, Assiut University, Assiut, Egypt
| | - Gamal Afifi
- Department of Physics, Faculty of Science, Jazan University, Jazan, KSA
- National Institute for Laser Enhanced Sciences, Cairo University
, Giza, Egypt
| | | | - Asmaa MS Gomaa
- Medical Physiology Department, Faculty of Medicine, Assiut University, Assiut, Egypt
| | - Mahmoud Abd-Elkareem
- Department of Anatomy and Histology, Faculty of Veterinary Medicine, Assiut University, Egypt
| | - Alaa Sayed Abou-Elhamd
- Department of Anatomy and Histology, Faculty of Veterinary Medicine, Assiut University, Egypt
- Department of Medical Laboratory Technology, Faculty of Applied Medical Sciences, Jazan University, Jazan, Saudi Arabia
| | | | - Ghada A Mohamed
- Endocrine Unit, Department of Internal Medicine, Faculty of Medicine, Assiut University, Assiut, Egypt
| | - Helal F Hetta
- Department of Medical Microbiology and Immunology, Faculty of Medicine, Assiut University, Assiut, Egypt
- Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, USA
- Correspondence: Helal F HettaDepartment of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, 231 Albert B. Sabin Way, PO Box 670595, OH45267-0595, USAEmail
| | - Ahmed M Kotb
- Department of Anatomy and Histology, Faculty of Veterinary Medicine, Assiut University, Egypt
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Kelly SC, Patel NN, Eccardt AM, Fisher JS. Glucose-dependent trans-plasma membrane electron transport and p70 S6k phosphorylation in skeletal muscle cells. Redox Biol 2018; 27:101075. [PMID: 30578122 PMCID: PMC6859557 DOI: 10.1016/j.redox.2018.101075] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Revised: 12/07/2018] [Accepted: 12/10/2018] [Indexed: 11/05/2022] Open
Abstract
The reduction of extracellular oxidants by intracellular electrons is known as trans-plasma membrane electron transport (tPMET). The goal of this study was to characterize a role of tPMET in the sensing of glucose as a physiological signal. tPMET from C2C12 myotubes was monitored using a cell-impermeable extracellular electron acceptor, water-soluble tetrazolium salt-1 (WST-1). Superoxide dismutase in the incubation medium or exposure to an NADPH oxidase (NOX) isoform 1/4 inhibitor suppressed WST-1 reduction by 70%, suggesting a role of NOXs in tPMET. There was a positive correlation between medium glucose concentration and WST-1 reduction, suggesting that tPMET is a glucose-sensing process. WST-1 reduction was also decreased by an inhibitor of the pentose phosphate pathway, dehydroepiandrosterone. In contrast, glycolytic inhibitors, 3PO and sodium fluoride, did not affect WST-1 reduction. Thus, it appears that glucose uptake and processing in the pentose phosphate pathway drives NOX-dependent tPMET. Western blot analysis demonstrated that p70S6k phosphorylation is glucose-dependent, while the phosphorylation of AKT and MAPK did not differ in the presence or absence of glucose. Further, phosphorylation of p70S6k was dependent upon NOX enzymes. Finally, glucose was required for full stimulation of p70S6k by insulin, again in a fashion prevented by NOX inhibition. Taken together, the data suggest that muscle cells have a novel glucose-sensing mechanism dependent on NADPH production and NOX activity, culminating in increased p70S6k phosphorylation.
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Affiliation(s)
- Shannon C Kelly
- Department of Biology, Saint Louis University, St. Louis, MO, United States
| | - Neej N Patel
- Department of Biology, Saint Louis University, St. Louis, MO, United States
| | - Amanda M Eccardt
- Department of Biology, Saint Louis University, St. Louis, MO, United States
| | - Jonathan S Fisher
- Department of Biology, Saint Louis University, St. Louis, MO, United States.
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28
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Previte DM, Piganelli JD. Reactive Oxygen Species and Their Implications on CD4 + T Cells in Type 1 Diabetes. Antioxid Redox Signal 2018; 29:1399-1414. [PMID: 28990401 DOI: 10.1089/ars.2017.7357] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Previous work has indicated that type 1 diabetes (T1D) pathology is highly driven by reactive oxygen species (ROS). One way in which ROS shape the autoimmune response demonstrated in T1D is by promoting CD4+ T cell activation and differentiation. As CD4+ T cells are a significant contributor to pancreatic β cell destruction in T1D, understanding how ROS impact their development, activation, and differentiation is critical. Recent Advances: CD4+ T cells themselves generate ROS via nicotinamide adenine dinucleotide phosphate (NADPH) oxidase expression and electron transport chain activity. Moreover, T cells can also be exposed to exogenous ROS generated by other immune cells (e.g., macrophages and dendritic cells) and β cells. Genetically modified animals and ROS inhibitors have demonstrated that ROS blockade during activation results in CD4+ T cell hyporesponsiveness and reduced diabetes incidence. Critical Issues and Future Directions: Although the majority of studies with regard to T1D and CD4+ T cells have been done to examine the influence of redox on CD4+ T cell activation, this is not the only circumstance in which a T cell can be impacted by redox. ROS and redox have also been shown to play roles in CD4+ T cell-related tolerogenic mechanisms, including thymic selection and regulatory T cell-mediated suppression. However, the effect of these mechanisms with respect to T1D pathogenesis remains elusive. Therefore, pursuing these avenues may provide valuable insight into the global role of ROS and redox in autoreactive CD4+ T cell formation and function.
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Affiliation(s)
- Dana M Previte
- Department of Surgery, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center , Pittsburgh, Pennsylvania
| | - Jon D Piganelli
- Department of Surgery, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center , Pittsburgh, Pennsylvania
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29
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Chen L, Zhang J, Li C, Wang Z, Li J, Zhao D, Wang S, Zhang H, Huang Y, Guo X. Glycine Transporter-1 and glycine receptor mediate the antioxidant effect of glycine in diabetic rat islets and INS-1 cells. Free Radic Biol Med 2018; 123:53-61. [PMID: 29753073 DOI: 10.1016/j.freeradbiomed.2018.05.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 04/30/2018] [Accepted: 05/08/2018] [Indexed: 12/18/2022]
Abstract
Oxidative stress is the main inducer of β-cell damage, which underlies the pathogenesis of diabetes. Evidence suggests that glycine, a recognized antioxidant, may improve β-cell function; however, its mechanism in protecting diabetic β-cells against oxidative stress has not been directly investigated. Using a streptozotocin-induced diabetic rat model and INS-1 pancreatic β-cells, we evaluated whether glycine can attenuate diabetic β-cell damage induced by oxidative stress. In diabetic rats, glycine stimulated insulin secretion; enhanced plasma glutathione (GSH), catalase and superoxide dismutase levels; reduced plasma 8-hydroxy-2 deoxyguanosine and islet p22phox levels; and improved islet β-cell mitochondrial degeneration and insulin granule degranulation. In INS-1 cells, glycine reduced the intracellular reactive oxygen species (ROS) concentration and inhibited apoptosis induced by high glucose or H2O2. Glycine transporter-1 inhibitor blocked the antioxidative effect of glycine by reducing the intracellular GSH content, and glycine receptor inhibitor reversed the glycine antioxidative effect by blocking p22phox. Collectively, our findings reveal a mechanism by which glycine protects diabetic β-cells against damage caused by oxidative stress by increasing glycine transporter-1-mediated synthesis of GSH and by reducing glycine receptor-mediated ROS production.
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Affiliation(s)
- Lei Chen
- Department of Endocrinology, Peking University First Hospital, No. 8 Xi Shi Ku Street, Xi Cheng District, Beijing 100034, China
| | - Junqing Zhang
- Department of Endocrinology, Peking University First Hospital, No. 8 Xi Shi Ku Street, Xi Cheng District, Beijing 100034, China.
| | - Changhong Li
- Division of Endocrinology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA.
| | - Ziwei Wang
- Department of Endocrinology, Peking University First Hospital, No. 8 Xi Shi Ku Street, Xi Cheng District, Beijing 100034, China
| | - Jingjing Li
- Department of Endocrinology, Peking University First Hospital, No. 8 Xi Shi Ku Street, Xi Cheng District, Beijing 100034, China
| | - Dan Zhao
- Department of Endocrinology, Peking University First Hospital, No. 8 Xi Shi Ku Street, Xi Cheng District, Beijing 100034, China
| | - Suxia Wang
- Laboratory of Electron Microscopy, Peking University First Hospital, Beijing 100034, China
| | - Hong Zhang
- Department of Endocrinology, Peking University First Hospital, No. 8 Xi Shi Ku Street, Xi Cheng District, Beijing 100034, China
| | - Youyuan Huang
- Department of Endocrinology, Peking University First Hospital, No. 8 Xi Shi Ku Street, Xi Cheng District, Beijing 100034, China
| | - Xiaohui Guo
- Department of Endocrinology, Peking University First Hospital, No. 8 Xi Shi Ku Street, Xi Cheng District, Beijing 100034, China
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30
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Barlow J, Solomon TPJ, Affourtit C. Pro-inflammatory cytokines attenuate glucose-stimulated insulin secretion from INS-1E insulinoma cells by restricting mitochondrial pyruvate oxidation capacity - Novel mechanistic insight from real-time analysis of oxidative phosphorylation. PLoS One 2018; 13:e0199505. [PMID: 29953508 PMCID: PMC6023166 DOI: 10.1371/journal.pone.0199505] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Accepted: 06/10/2018] [Indexed: 11/30/2022] Open
Abstract
Pro-inflammatory cytokines cause pancreatic beta cell failure during the development of type 2 diabetes. This beta cell failure associates with mitochondrial dysfunction, but the precise effects of cytokines on mitochondrial respiration remain unclear. To test the hypothesis that pro-inflammatory cytokines impair glucose-stimulated insulin secretion (GSIS) by inhibiting oxidative ATP synthesis, we probed insulin release and real-time mitochondrial respiration in rat INS-1E insulinoma cells that were exposed to a combination of 2 ng/mL interleukin-1-beta and 50 ng/mL interferon-gamma. We show that 24-h exposure to these cytokines dampens both glucose- and pyruvate-stimulated insulin secretion (P < 0.0001 and P < 0.05, respectively), but does not affect KCl-induced insulin release. Mirroring secretory defects, glucose- and pyruvate-stimulated mitochondrial respiration are lowered after cytokine exposure (P < 0.01). Further analysis confirms that cytokine-induced mitochondrial respiratory defects occur irrespective of whether fuel oxidation is coupled to, or uncoupled from, ATP synthesis. These observations demonstrate that pro-inflammatory cytokines attenuate GSIS by restricting mitochondrial pyruvate oxidation capacity. Interleukin-1-beta and interferon-gamma also increase mitochondrial superoxide levels (P < 0.05), which may reinforce the inhibition of pyruvate oxidation, and cause a modest (20%) but significant (P < 0.01) loss of INS-1E cells. Cytokine-induced INS-1E cell failure is insensitive to palmitoleate and linoleate, which is at odds with the cytoprotection offered by unsaturated fatty acids against harm caused by nutrient excess. Our data disclose a mitochondrial mechanism for cytokine-impaired GSIS in INS-1E cells, and suggest that inflammatory and nutrient-related beta cell failure emerge, at least partly, through distinct paths.
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Affiliation(s)
- Jonathan Barlow
- School of Biomedical and Healthcare Sciences, University of Plymouth, Plymouth, United Kingdom
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Thomas P. J. Solomon
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Birmingham, United Kingdom
- Institute for Metabolism and Systems Research (IMSR), University of Birmingham, Birmingham, United Kingdom
| | - Charles Affourtit
- School of Biomedical and Healthcare Sciences, University of Plymouth, Plymouth, United Kingdom
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31
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Sidarala V, Kowluru A. Exposure to chronic hyperglycemic conditions results in Ras-related C3 botulinum toxin substrate 1 (Rac1)-mediated activation of p53 and ATM kinase in pancreatic β-cells. Apoptosis 2018; 22:597-607. [PMID: 28220272 DOI: 10.1007/s10495-017-1354-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Chronic hyperglycemia (HG) promotes pancreatic islet dysfunction which leads to the onset of T2DM. This study is aimed at defining regulatory roles of Rac1, a small G-protein, in the activation of p53 and ATM kinase in pancreatic β-cells, under the duress of HG conditions. We report significant stimulatory effects of HG (20 mM; 24 h) on p53 activation in INS-1 832/13 cells, normal rodent and human islets. Pharmacological inhibition of Rac1 (EHT1864 or NSC23766) significantly suppressed HG-induced p53 activation in INS-1 832/13 cells and rat islets, suggesting novel roles for this small G-protein in the activation of p53. Inhibition of Rac1 geranylgeranylation with simvastatin or GGTI-2147, significantly attenuated HG-induced p53 activation, suggesting requisite roles for this signaling step in HG-mediated effects on β-cells. HG-induced p53 activation was also suppressed by SB203580, a known inhibitor of p38MAPK. Additionally, we observed increased activation of ATM kinase under HG conditions, which was blocked in presence of EHT1864. Furthermore, pharmacological inhibition of ATM kinase (KU55933) reduced activation of ATM kinase, but not p53, suggesting that HG-mediated activation of p53 and ATM could represent independent pro-apoptotic events. In conclusion, these data indicate that sustained activation of Rac1-p38MAPK signaling axis leads to activation of p53 leading to β-cell dysfunction under the duress of chronic hyperglycemic conditions.
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Affiliation(s)
- Vaibhav Sidarala
- Beta-Cell Biochemistry Laboratory, John D. Dingell VA Medical Center, B-4237 Research Service, 4646 John R, Detroit, MI, 48201, USA.,Department of Pharmaceutical Sciences, Wayne State University, Detroit, MI, 48201, USA.,Division of Metabolism, Endocrinology and Diabetes (MEND), Department of Internal Medicine, Brehm Diabetes Research Center, University of Michigan Medical School, Ann Arbor, MI, 48105-1912, USA
| | - Anjaneyulu Kowluru
- Beta-Cell Biochemistry Laboratory, John D. Dingell VA Medical Center, B-4237 Research Service, 4646 John R, Detroit, MI, 48201, USA. .,Department of Pharmaceutical Sciences, Wayne State University, Detroit, MI, 48201, USA.
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32
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Warren JL, Hoxha E, Jumbo-Lucioni P, De Luca M. Reduction of Syndecan Transcript Levels in the Insulin-Producing Cells Affects Glucose Homeostasis in Adult Drosophila melanogaster. DNA Cell Biol 2017; 36:959-965. [PMID: 28945109 DOI: 10.1089/dna.2017.3912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Signaling by direct cell-matrix interactions has been shown to impact the transcription, secretion, and storage of insulin in mammalian β cells. However, more research is still needed in this area. Syndecans are transmembrane heparan sulfate proteoglycans that function independently and in synergy with integrin-mediated signaling to mediate cell adhesion to the extracellular matrix. In this study, we used the model organism Drosophila melanogaster to determine whether knockdown of the Syndecan (Sdc) gene expression specifically in the insulin-producing cells (IPCs) might affect insulin-like peptide (ILP) production and secretion. IPCs of adult flies produce three ILPs (ILP2, ILP3, and ILP5), which have significant homology to mammalian insulin. We report that flies with reduced Sdc expression in the IPCs did not show any difference in the expression of ilp genes compared to controls. However, they had significantly reduced levels of the circulating ILP2 protein, higher circulating carbohydrates, and were less glucose tolerant than control flies. Finally, we found that IPCs-specific Sdc knockdown led to reduced levels of head Glucose transporter1 gene expression, extracellular signal-regulated kinase phosphorylation, and reactive oxygen species. Taken together, our findings suggest a cell autonomous role for Sdc in insulin release in D. melanogaster.
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Affiliation(s)
- Jonathan L Warren
- 1 Department of Nutrition Sciences, University of Alabama at Birmingham , Birmingham, Alabama
| | - Eneida Hoxha
- 1 Department of Nutrition Sciences, University of Alabama at Birmingham , Birmingham, Alabama.,2 Department of Biology, Ecology and Earth Science, University of Calabria , Rende, Italy
| | - Patricia Jumbo-Lucioni
- 1 Department of Nutrition Sciences, University of Alabama at Birmingham , Birmingham, Alabama.,3 Department of Pharmaceutical, Social and Administrative Sciences, McWhorter School of Pharmacy, Samford University , Birmingham, Alabama
| | - Maria De Luca
- 1 Department of Nutrition Sciences, University of Alabama at Birmingham , Birmingham, Alabama
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33
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Characterization of the post-prandial insulinemic response and low glycaemic index of a soy beverage. PLoS One 2017; 12:e0182762. [PMID: 28793331 PMCID: PMC5549974 DOI: 10.1371/journal.pone.0182762] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 07/24/2017] [Indexed: 02/07/2023] Open
Abstract
Soybean is recognized as rich source of bioactive compounds for the improvement of glucose homeostasis. However, the post-prandial mechanisms of action have not been extensively described. The aim of this study is to determine the changes in glucose homeostasis and related factors after acute intake of a soy beverage. Twenty-nine subjects (15 women and 14 men, with an average age of 19.5 ± 1.2) ingested 500 mL of water, glucose (20.5 g/500 mL) and soy beverage (20 g of carbohydrate) in three separate sessions. Capillary blood glucose was monitored every 15 min until 120 min post-prandial, and blood samples were collected at baseline and after 60 min for insulin, incretin, free amino acids, antioxidant capacity and inflammation marker analysis. The increase in capillary glucose after soy-beverage intake was negligible. This is explained in part by an increase in 83% in insulin levels than induced with glucose alone, which is mainly mediated by a low insulin degradation ratio (determined by c-peptide ratio), incretins and likely also by the modulation of the antioxidant environment. No associations were observed between the insulin levels and soy amino acid uptake. It could be concluded that the acute low glycaemic response of a soy beverage may involves a relationship between incretin and insulin secretion and insulin degradation.
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Advanced oxidation protein products promote NADPH oxidase-dependent β-cell destruction and dysfunction through the Bcl-2/Bax apoptotic pathway. J Transl Med 2017; 97:792-805. [PMID: 28263293 DOI: 10.1038/labinvest.2017.24] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Revised: 01/16/2017] [Accepted: 01/25/2017] [Indexed: 01/12/2023] Open
Abstract
The accumulation of plasma advanced oxidation protein products (AOPPs) has been linked with diverse disorders, including diabetes, chronic kidney disease, obesity, and metabolic syndrome. The aim of the present study was to evaluate the pathophysiological relevance of AOPPs in β-cell destruction and dysfunction. Exposure of cultured rat β-cells (INS-1) to AOPPs induced an increase in Bax expression, caspase-3 activity, and apoptosis as well as a decrease in Bcl-2 expression in a dose- and time-dependent manner. AOPP challenge rapidly increased the production of intracellular superoxide by activation of NADPH oxidases, demonstrated by p47phox translocation and interaction with p22phox and gp91phox, and this in turn led to apoptosis. AOPPs treatment resulted in β-cell apoptosis, AOPPs accumulation, and decreased insulin content in pancreas and plasma in unilateral nephrectomized rats. Chronic inhibition of NADPH oxidase by apocynin prevented β-cell apoptosis and ameliorated insulin deficiency in AOPP-challenged rats. This study demonstrates for the first time that accumulation of AOPPs promotes NADPH oxidase-dependent β-cell destruction and dysfunction by the Bcl-2/Bax-caspase apoptotic pathway. This finding may provide a mechanistic explanation for β-cell destruction and dysfunction in patients with diverse disorders.
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35
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Kowluru A. Tiam1/Vav2-Rac1 axis: A tug-of-war between islet function and dysfunction. Biochem Pharmacol 2017; 132:9-17. [PMID: 28202288 DOI: 10.1016/j.bcp.2017.02.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Accepted: 02/07/2017] [Indexed: 10/20/2022]
Abstract
Glucose-stimulated insulin secretion [GSIS] from the islet β-cell involves a well-orchestrated interplay between metabolic and cationic events. It is well established that intracellular generation of adenine and guanine nucleotide triphosphates [e.g., ATP and GTP] represents one of the requisite signaling steps in GSIS. The small molecular mass GTP-binding proteins [G-proteins; e.g., Rac1 and Cdc42] have been shown to regulate islet β-cell function including actin cytoskeletal remodeling and fusion of insulin granules with the plasma membrane for GSIS to occur. In this context, several regulatory factors for these G-proteins have been identified in the pancreatic β-cell; these include guanine nucleotide exchange factors [GEFs] and guanine nucleotide dissociation inhibitors [GDI]. Recent pharmacological and molecular biological evidence identified Tiam1 and Vav2 as GEFs for Rac1 in promoting physiological insulin secretion. Paradoxically, emerging evidence in multiple cell types, including the islet β-cell, suggests key roles for Rac1 in the onset of cellular dysfunction under conditions of metabolic stress and diabetes. Furthermore, functional inactivation of either Tiam1 or Vav2 appears to attenuate sustained activation of Rac1 and its downstream signaling events [activation of stress kinases] under conditions of metabolic stress. Together, these findings suggest both "friendly" and "non-friendly" roles for Tiam1/Vav2-Rac1 signaling axis in islet β-cell in health and diabetes. Our current understanding of the field and the knowledge gaps that exist in this area of islet biology are heighted herein. Furthermore, potential caveats in the specificity and selectivity of pharmacological inhibitors that are available currently are discussed in this Commentary.
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Affiliation(s)
- Anjaneyulu Kowluru
- Beta-Cell Biochemistry Laboratory, 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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36
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Kuzmenko DI, Klimentyeva TK. Role of Ceramide in Apoptosis and Development of Insulin Resistance. BIOCHEMISTRY (MOSCOW) 2017; 81:913-27. [PMID: 27682164 DOI: 10.1134/s0006297916090017] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
This review presents data on the functional biochemistry of ceramide, one of the key sphingolipids with properties of a secondary messenger. Molecular mechanisms of the involvement of ceramide in apoptosis in pancreatic β-cells and its role in the formation of insulin resistance in pathogenesis of type 2 diabetes are reviewed. One of the main predispositions for the development of insulin resistance and diabetes is obesity, which is associated with ectopic fat deposition and significant increase in intracellular concentrations of cytotoxic ceramides. A possible approach to the restoration of tissue sensitivity to insulin in type 2 diabetes based on selective reduction of the content of cytotoxic ceramides is discussed.
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Affiliation(s)
- D I Kuzmenko
- Siberian State Medical University, Ministry of Healthcare of the Russian Federation, Tomsk, 634050, Russia.
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37
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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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Simões D, Riva P, Peliciari-Garcia RA, Cruzat VF, Graciano MF, Munhoz AC, Taneda M, Cipolla-Neto J, Carpinelli AR. Melatonin modifies basal and stimulated insulin secretion via NADPH oxidase. J Endocrinol 2016; 231:235-244. [PMID: 27803236 DOI: 10.1530/joe-16-0259] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 10/04/2016] [Indexed: 01/10/2023]
Abstract
Melatonin is a hormone synthesized in the pineal gland, which modulates several functions within the organism, including the synchronization of glucose metabolism and glucose-stimulated insulin secretion (GSIS). Melatonin can mediate different signaling pathways in pancreatic islets through two membrane receptors and via antioxidant or pro-oxidant enzymes modulation. NADPH oxidase (NOX) is a pro-oxidant enzyme responsible for the production of the reactive oxygen specie (ROS) superoxide, generated from molecular oxygen. In pancreatic islets, NOX-derived ROS can modulate glucose metabolism and regulate insulin secretion. Considering the roles of both melatonin and NOX in islets, the aim of this study was to evaluate the association of NOX and ROS production on glucose metabolism, basal and GSIS in pinealectomized rats (PINX) and in melatonin-treated isolated pancreatic islets. Our results showed that ROS content derived from NOX activity was increased in PINX at baseline (2.8 mM glucose), which was followed by a reduction in glucose metabolism and basal insulin secretion in this group. Under 16.7 mM glucose, an increase in both glucose metabolism and GSIS was observed in PINX islets, without changes in ROS content. In isolated pancreatic islets from control animals incubated with 2.8 mM glucose, melatonin treatment reduced ROS content, whereas in 16.7 mM glucose, melatonin reduced ROS and GSIS. In conclusion, our results demonstrate that both basal and stimulated insulin secretion can be regulated by melatonin through the maintenance of ROS homeostasis in pancreatic islets.
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Affiliation(s)
- Daniel Simões
- Department of Physiology and BiophysicsInstitute of Biomedical Sciences-I, University of São Paulo, São Paulo, Brazil
| | - Patrícia Riva
- Department of Physiology and BiophysicsInstitute of Biomedical Sciences-I, University of São Paulo, São Paulo, Brazil
| | - Rodrigo Antonio Peliciari-Garcia
- Department of Physiology and BiophysicsInstitute of Biomedical Sciences-I, University of São Paulo, São Paulo, Brazil
- Department of Biological SciencesLaboratory of Biosystems, Federal University of São Paulo, Diadema, São Paulo, Brazil
| | - Vinicius Fernandes Cruzat
- Department of Physiology and BiophysicsInstitute of Biomedical Sciences-I, University of São Paulo, São Paulo, Brazil
| | - Maria Fernanda Graciano
- Department of Physiology and BiophysicsInstitute of Biomedical Sciences-I, University of São Paulo, São Paulo, Brazil
| | - Ana Claudia Munhoz
- Department of Physiology and BiophysicsInstitute of Biomedical Sciences-I, University of São Paulo, São Paulo, Brazil
| | - Marco Taneda
- Department of Physiology and BiophysicsInstitute of Biomedical Sciences-I, University of São Paulo, São Paulo, Brazil
| | - José Cipolla-Neto
- Department of Physiology and BiophysicsInstitute of Biomedical Sciences-I, University of São Paulo, São Paulo, Brazil
| | - Angelo Rafael Carpinelli
- Department of Physiology and BiophysicsInstitute of Biomedical Sciences-I, University of São Paulo, São Paulo, Brazil
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Carvalho DS, Diniz MM, Haidar AA, Cavanal MDF, da Silva Alves E, Carpinelli AR, Gil FZ, Hirata AE. L-Arginine supplementation improves insulin sensitivity and beta cell function in the offspring of diabetic rats through AKT and PDX-1 activation. Eur J Pharmacol 2016; 791:780-787. [PMID: 27717730 DOI: 10.1016/j.ejphar.2016.10.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Revised: 09/27/2016] [Accepted: 10/03/2016] [Indexed: 01/11/2023]
Abstract
Maternal hyperglycemia can result in defects in glucose metabolism and pancreatic β-cell function in offspring. The purpose of this study was to evaluate the impact of maternal diabetes mellitus on pancreatic islets, muscle and adipose tissue of the offspring, with or without oral l-Arginine supplementation. The induction of diabetes was performed using streptozotocin (60mg/kg). Animals were studied at 3 months of age and treatment (sucrose or l-Arginine) was administered from weaning. We observed that l-Arg improved insulin sensitivity in the offspring of diabetic mothers (DA), reflected by higher insulin-induced phosphorylation of Akt in muscle and adipose tissue. Insulin resistance is associated with increased oxidative stress and the NADPH oxidase enzyme plays an important role. Our results showed that the augmented interaction of p47PHOX with gp91PHOX subunits of the enzyme in skeletal muscle tissue in the offspring of diabetic rats (DV) was abolished after l-Arg treatment in DA rats. Maternal diabetes caused alterations in the islet functionality of the offspring leading to increased insulin secretion at both low (2.8mM) and high (16.7mM) concentrations of glucose. l-Arg reverses this effect, suggesting that it may be an important modulator in the insulin secretory process. In addition it is possible that l-Arg exerts its effects directly onto essential molecules for the maintenance and survival of pancreatic islets, decreasing protein expression of p47PHOX while increasing Akt phosphorylation and PDX-1 expression. The mechanism by which l-Arg exerts its beneficial effects may involve nitric oxide bioavailability since treatment restored NO levels in the pancreas.
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Affiliation(s)
| | - Marilia Melo Diniz
- Department of Physiology - Federal University of São Paulo, UNIFESP, Brazil
| | - André Abour Haidar
- Department of Physiology - Federal University of São Paulo, UNIFESP, Brazil
| | | | | | - Angelo Rafael Carpinelli
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, USP, Brazil
| | - Frida Zaladek Gil
- Department of Physiology - Federal University of São Paulo, UNIFESP, Brazil
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Veluthakal R, Sidarala V, Kowluru A. NSC23766, a Known Inhibitor of Tiam1-Rac1 Signaling Module, Prevents the Onset of Type 1 Diabetes in the NOD Mouse Model. Cell Physiol Biochem 2016; 39:760-7. [PMID: 27467102 DOI: 10.1159/000445666] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/27/2016] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND/AIMS Type 1 diabetes (T1D) is characterized by absolute insulin deficiency due to destruction of pancreatic β-cells by cytokines (e.g., interleukin-1β; IL-1β) released by invading immune cells. The mechanisms by which these cytokines induce β-cell dysfunction remain poorly understood. Recent evidence suggests that excessive generation of reactive oxygen species (ROS) by the phagocyte-like NADPH oxidase2 (Nox2), along with significantly low levels of antioxidants in β-cells, drive them toward oxidative damage. Rac1, a small G-protein, is one of the members of Nox2 holoenzyme. We recently reported that NSC23766, a known inhibitor of Rac1, significantly attenuated cytokine-induced Nox2 activation and ROS generation in pancreatic islet β-cells in vitro. Herein, we determined the effects of NSC23766 (2.5 mg/kg/day, i.p/daily) on the development of diabetes in the NOD mouse, a model for T1D. METHODS Two groups of experimental animals (Balb/c and NOD mice) received NSC23766, while the two control groups received equal volume of saline. Body weights and blood glucose were measured every week for 34 weeks. Rac1 activation in pancreatic islets was measured by GLISA activation assay. Rac1 and CHOP expression was determined by Western Blotting. RESULTS Our findings indicate that administration of NSC23766 significantly prevented the development of spontaneous diabetes in the NOD mice. Furthermore, NSC23766 markedly suppressed Rac1 expression and activity and the endoplasmic reticulum stress (CHOP expression) in NOD islets. CONCLUSIONS Our findings provide the first evidence implicating the role of Tiam1-Rac1-Nox2 signaling pathway in the onset of spontaneous diabetes in the NOD mouse model.
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Affiliation(s)
- Rajakrishnan Veluthakal
- Department of Molecular and Cellular Endocrinology, Diabetes and Metabolic Research Institute, City of Hope/BRI, Duarte, USA
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Veluthakal R, Tunduguru R, Arora DK, Sidarala V, Syeda K, Vlaar CP, Thurmond DC, Kowluru A. VAV2, a guanine nucleotide exchange factor for Rac1, regulates glucose-stimulated insulin secretion in pancreatic beta cells. Diabetologia 2015. [PMID: 26224100 PMCID: PMC4591202 DOI: 10.1007/s00125-015-3707-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
AIMS/HYPOTHESIS Rho GTPases (Ras-related C3 botulinum toxin substrate 1 [Rac1] and cell division cycle 42 [Cdc42]) have been shown to regulate glucose-stimulated insulin secretion (GSIS) via cytoskeletal remodelling, trafficking and fusion of insulin-secretory granules with the plasma membrane. GTP loading of these G proteins, which is facilitated by GDP/GTP exchange factors, is a requisite step in the regulation of downstream effector proteins. Guanine nucleotide exchange factor VAV2 (VAV2), a member of the Dbl family of proteins, has been identified as one of the GDP/GTP exchange factors for Rac1. Despite recent evidence on the regulatory roles of VAV2 in different cell types, roles of this guanine nucleotide exchange factor in the signalling events leading to GSIS remain undefined. Using immunological, short interfering RNA (siRNA), pharmacological and microscopic approaches we investigated the role of VAV2 in GSIS from islet beta cells. METHODS Co-localisation of Rac1 and VAV2 was determined by Triton X-114 phase partition and confocal microscopy. Glucose-induced actin remodelling was quantified by live cell imaging using the LifeAct-GFP fluorescent biosensor. Rac1 activation was determined by G protein linked immunosorbent assay (G-LISA). RESULTS Western blotting indicated that VAV2 is expressed in INS-1 832/13 beta cells, normal rat islets and human islets. Vav2 siRNA markedly attenuated GSIS in INS-1 832/13 cells. Ehop-016, a newly discovered small molecule inhibitor of the VAV2-Rac1 interaction, or siRNA-mediated knockdown of VAV2 markedly attenuated glucose-induced Rac1 activation and GSIS in INS-1 832/13 cells. Pharmacological findings were recapitulated in primary rat islets. A high glucose concentration promoted co-localisation of Rac1 and VAV2. Real-time imaging in live cells indicated a significant inhibition of glucose-induced cortical actin remodelling by Ehop-016. CONCLUSIONS/INTERPRETATION Our data provide the first evidence to implicate VAV2 in glucose-induced Rac1 activation, actin remodelling and GSIS in pancreatic beta cells.
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Affiliation(s)
- Rajakrishnan Veluthakal
- Beta Cell Biochemistry Laboratory, John D. Dingell VA Medical Center, 4646 John R, Detroit, MI, 48201, USA
- Department of Pediatrics, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Ragadeepthi Tunduguru
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Daleep Kumar Arora
- Immunobiology and Cancer Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Vaibhav Sidarala
- Beta Cell Biochemistry Laboratory, John D. Dingell VA Medical Center, 4646 John R, Detroit, MI, 48201, USA
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy, Wayne State University, Detroit, MI, USA
| | - Khadija Syeda
- Beta Cell Biochemistry Laboratory, John D. Dingell VA Medical Center, 4646 John R, Detroit, MI, 48201, USA
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy, Wayne State University, Detroit, MI, USA
| | - Cornelis P Vlaar
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Puerto Rico, Medical Sciences Campus, San Juan, Puerto Rico
| | - Debbie C Thurmond
- Department of Pediatrics, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN, USA
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Anjaneyulu Kowluru
- Beta Cell Biochemistry Laboratory, John D. Dingell VA Medical Center, 4646 John R, Detroit, MI, 48201, USA.
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy, Wayne State University, Detroit, MI, USA.
- B-4237 Research Service, John D. Dingell VA Medical Center, 4646 John R, Detroit, MI, 48201, USA.
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Anvari E, Wikström P, Walum E, Welsh N. The novel NADPH oxidase 4 inhibitor GLX351322 counteracts glucose intolerance in high-fat diet-treated C57BL/6 mice. Free Radic Res 2015; 49:1308-18. [DOI: 10.3109/10715762.2015.1067697] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Kowluru A, Kowluru RA. Protein prenylation in islet β-cell function in health and diabetes: Putting the pieces of the puzzle together. Biochem Pharmacol 2015. [PMID: 26215874 DOI: 10.1016/j.bcp.2015.07.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Post-translational prenylation involves incorporation of 15-(farnesyl) or 20-(geranylgeranyl) carbon derivatives of mevalonic acid into highly conserved C-terminal cysteines of proteins. The farnesyl transferase (FTase) and the geranylgeranyl transferase (GGTase) mediate incorporation of farnesyl and geranylgeranyl groups, respectively. At least 300 proteins are prenylated in the human genome; the majority of these are implicated in cellular processes including growth, differentiation, cytoskeletal function and vesicle trafficking. From a functional standpoint, isoprenylation is requisite for targeting of modified proteins to relevant cellular compartments for regulation of effector proteins. Pharmacological and molecular biological studies have provided compelling evidence for key roles of this signaling pathway in physiological insulin secretion in normal rodent and human islets. Recent evidence indicates that inhibition of prenylation results in mislocalization of unprenylated proteins, and surprisingly, they remain in active (GTP-bound) conformation. Sustained activation of G proteins has been reported in mice lacking GGTase, suggesting alternate mechanisms for the activation of non-prenylated G proteins. These findings further raise an interesting question if mislocalized, non-prenylated and functionally active G proteins cause cellular pathology since aberrant protein prenylation has been implicated in the onset of cardiovascular disease and diabetes. Herein, we overview the existing evidence to implicate prenylation in islet function and potential defects in this signaling pathways in the diabetic β-cell. We will also identify critical knowledge gaps that need to be addressed for the development of therapeutics to halt defects in these signaling steps in β cells in models of impaired insulin secretion, metabolic stress and diabetes.
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Affiliation(s)
- Anjaneyulu Kowluru
- John D. Dingell VA Medical Center, Detroit, MI 48201, United States; Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI 48201, United States.
| | - Renu A Kowluru
- Kresge Eye Institute, Wayne State University, Detroit, MI 48201, United States
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Phagocyte-like NADPH oxidase (Nox2) promotes activation of p38MAPK in pancreatic β-cells under glucotoxic conditions: Evidence for a requisite role of Ras-related C3 botulinum toxin substrate 1 (Rac1). Biochem Pharmacol 2015; 95:301-10. [PMID: 25881746 DOI: 10.1016/j.bcp.2015.04.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 04/06/2015] [Indexed: 12/23/2022]
Abstract
It is well established that glucotoxicity (caused by high glucose concentrations; HG) underlies pathogenesis of islet dysfunction in diabetes. We have recently demonstrated that Nox2 plays a requisite role in the generation of reactive oxygen species (ROS) under HG conditions, resulting in mitochondrial dysregulation and loss of islet β-cell function. Herein, we investigated roles of Nox2 in the regulation of downstream stress kinase (p38MAPK) activation under HG conditions (20mM; 24h) in normal rodent islets and INS-1 832/13 cells. We observed that gp91-ds-tat, a specific inhibitor of Nox2, but not its inactive analog, significantly attenuated HG-induced Nox2 activation, ROS generation and p38MAPK activation, thus suggesting that Nox2 activation couples with p38MAPK activation. Since Rac1, is an integral member of the Nox2 holoenzyme, we also assessed the effects of Rac1 inhibitors (EHT 1864, NSC23766 and Ehop-016) on HG-induced p38MAPK activation in isolated β-cells. We report a significant inhibition of p38MAPK phosphorylation by Rac1 inhibitors, implying a regulatory role for Rac1 in promoting the Nox2-p38MAPK signaling axis in the β-cell under the duress of HG. 2-Bromopalmitate, a known inhibitor of protein (Rac1) palmitoylation, significantly reduced HG-induced p38MAPK phosphorylation. However, GGTI-2147, a specific inhibitor of geranylgeranylation of Rac1, failed to exert any significant effects on HG-induced p38MAPK activation. In conclusion, we present the first evidence that the Rac1-Nox2 signaling module plays novel regulatory roles in HG-induced p38MAPK activation and loss in glucose-stimulated insulin secretion (GSIS) culminating in metabolic dysfunction and the onset of diabetes.
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Yara S, Lavoie JC, Levy E. Oxidative stress and DNA methylation regulation in the metabolic syndrome. Epigenomics 2015; 7:283-300. [DOI: 10.2217/epi.14.84] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
DNA methylation is implicated in tissue-specific gene expression and genomic imprinting. It is modulated by environmental factors, especially nutrition. Modified DNA methylation patterns may contribute to health problems and susceptibility to complex diseases. Current advances have suggested that the metabolic syndrome (MS) is a programmable disease, which is characterized by epigenetic modifications of vital genes when exposed to oxidative stress. Therefore, the main objective of this paper is to critically review the central context of MS while presenting the most recent knowledge related to epigenetic alterations that are promoted by oxidative stress. Potential pro-oxidant mechanisms that orchestrate changes in methylation profiling and are related to obesity, diabetes and hypertension are discussed. It is anticipated that the identification and understanding of the role of DNA methylation marks could be used to uncover early predictors and define drugs or diet-related treatments able to delay or reverse epigenetic changes, thereby combating MS burden.
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Affiliation(s)
- Sabrina Yara
- Faculty of Medicine, Research Centre, Université de Montréal, CHU-Sainte-Justine, Montreal, QC, Canada, H3T 1C5
| | - Jean-Claude Lavoie
- Faculty of Medicine, Research Centre, Université de Montréal, CHU-Sainte-Justine, Montreal, QC, Canada, H3T 1C5
- Departments of Nutrition, Université de Montréal, Montreal, Quebec, Canada, H3T 1C5
| | - Emile Levy
- Faculty of Medicine, Research Centre, Université de Montréal, CHU-Sainte-Justine, Montreal, QC, Canada, H3T 1C5
- Departments of Nutrition, Université de Montréal, Montreal, Quebec, Canada, H3T 1C5
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Kashio M, Tominaga M. Redox Signal-mediated Enhancement of the Temperature Sensitivity of Transient Receptor Potential Melastatin 2 (TRPM2) Elevates Glucose-induced Insulin Secretion from Pancreatic Islets. J Biol Chem 2015; 290:12435-42. [PMID: 25817999 DOI: 10.1074/jbc.m115.649913] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Indexed: 01/08/2023] Open
Abstract
Transient receptor potential melastatin 2 (TRPM2) is a thermosensitive Ca(2+)-permeable cation channel expressed by pancreatic β cells where channel function is constantly affected by body temperature. We focused on the physiological functions of redox signal-mediated TRPM2 activity at body temperature. H2O2, an important molecule in redox signaling, reduced the temperature threshold for TRPM2 activation in pancreatic β cells of WT mice but not in TRPM2KO cells. TRPM2-mediated [Ca(2+)]i increases were likely caused by Ca(2+) influx through the plasma membrane because the responses were abolished in the absence of extracellular Ca(2+). In addition, TRPM2 activation downstream from the redox signal plus glucose stimulation enhanced glucose-induced insulin secretion. H2O2 application at 37 °C induced [Ca(2+)]i increases not only in WT but also in TRPM2KO β cells. This was likely due to the effect of H2O2 on KATP channel activity. However, the N-acetylcysteine-sensitive fraction of insulin secretion by WT islets was increased by temperature elevation, and this temperature-dependent enhancement was diminished significantly in TRPM2KO islets. These data suggest that endogenous redox signals in pancreatic β cells elevate insulin secretion via TRPM2 sensitization and activity at body temperature. The results in this study could provide new therapeutic approaches for the regulation of diabetic conditions by focusing on the physiological function of TRPM2 and redox signals.
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Affiliation(s)
- Makiko Kashio
- From the Division of Cell Signaling, Okazaki Institute for Integrative Bioscience (National Institute for Physiological Sciences), National Institutes of Natural Sciences, Okazaki 444-8787, Japan and
| | - Makoto Tominaga
- From the Division of Cell Signaling, Okazaki Institute for Integrative Bioscience (National Institute for Physiological Sciences), National Institutes of Natural Sciences, Okazaki 444-8787, Japan and the Department of Physiological Sciences, SOKENDAI (The Graduate University for Advanced Studies), Okazaki 444-8585, Japan
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Abstract
OBJECTIVES The aim of the study was to evaluate the potential changes induced by fish oil (FO) supplementation on the redox status of pancreatic islets from healthy rats. To test whether these effects were due to eicosapentaenoic acid and docosahexaenoic acid (ω-3), in vitro experiments were performed. METHODS Rats were supplemented with FO, and pancreatic islets were obtained. Islets were also treated in vitro with palmitate (P) or eicosapentaenoic acid + docosahexaenoic acid (ω-3). Insulin secretion (GSIS), glucose oxidation, protein expression, and superoxide content were analyzed. RESULTS The FO group showed a reduction in superoxide content. Moreover, FO reduced the expression of NAD(P)H oxidase subunits and increased superoxide dismutase, without altering β-cell function. Palmitate increased β-cell reactive oxygen species (ROS) production, apoptosis, and impaired GSIS. Under these conditions, ω-3 triggered a parallel reduction in ROS production and β-cell apoptosis induced by P and protected against the impairment in GSIS. There was no difference in mitochondrial ROS production. CONCLUSIONS Our results show that ω-3 protect pancreatic islets from alterations induced by P. In vivo FO supplementation modulates the redox state of pancreatic β-cell. Considering that in vitro effects do not involve mitochondrial superoxide production, we can speculate that this protection might involve NAD(P)H oxidase activity.
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Weaver JR, Grzesik W, Taylor-Fishwick DA. Inhibition of NADPH oxidase-1 preserves beta cell function. Diabetologia 2015; 58:113-21. [PMID: 25277953 DOI: 10.1007/s00125-014-3398-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Accepted: 09/09/2014] [Indexed: 02/07/2023]
Abstract
AIMS/HYPOTHESIS Upregulation of the reactive oxygen species (ROS)-producing enzyme NADPH oxidase (NOX)-1 in islets and beta cells follows acute exposure to inflammatory cytokines and is concomitant with beta cell dysfunction. NOX-1 is a candidate mediator of inflammation-induced beta cell dysfunction. This study aimed to determine whether selective inhibition of NADPH oxidase-1 presents a new strategy to preserve beta cell function. METHODS Induced beta cell dysfunction was studied in primary human donor islets, isolated mouse islets and murine beta cell lines. Islets and beta cells were stimulated with inflammatory cytokines (TNF-α, IL-1β, IFN-γ). NOX-1 activity was blocked by the selective inhibitor ML171. RESULTS Cytokine induction of intracellular ROS was reduced 80% with 1 μmol/l ML171 in murine beta cell lines (p < 0.01). Cytokine-induced apoptosis, measured by caspase-3 activation or quantified fluorescence microscopy, was prevented in islets and beta cell lines up to 100% with ML171 in a concentration-dependent manner (p < 0.05). Functionally, glucose-stimulated insulin secretion was abolished by cytokine exposure but preserved by ML171 in isolated mouse islets and murine beta cell lines. A feed-forward regulation of NOX-1 in islets and beta cell lines was disrupted by ML171. CONCLUSIONS/INTERPRETATION Stimulation of NOX-1 activity is a major component of inflammatory cytokine-induced beta cell dysfunction. Significant protection of beta cells is conferred with selective inhibition of NOX-1. Suppression of NOX-1 activity may present a new therapeutic strategy to preserve and protect beta cell function in diabetes.
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Affiliation(s)
- Jessica R Weaver
- Department of Microbiology and Molecular Cell Biology, LH 2128, Eastern Virginia Medical School, 700 W. Olney Road, Norfolk, VA, 23507, USA
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Islet NADPH oxidase activity modulates β-cell mass and endocrine function in rats with fructose-induced oxidative stress. Biochim Biophys Acta Gen Subj 2014; 1840:3475-82. [DOI: 10.1016/j.bbagen.2014.09.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 08/22/2014] [Accepted: 09/08/2014] [Indexed: 12/16/2022]
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50
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Hansen JB, Moen IW, Mandrup-Poulsen T. Iron: the hard player in diabetes pathophysiology. Acta Physiol (Oxf) 2014; 210:717-32. [PMID: 24521359 DOI: 10.1111/apha.12256] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 01/09/2014] [Accepted: 02/03/2014] [Indexed: 12/14/2022]
Abstract
The interest in the role of ferrous iron in diabetes pathophysiology has been revived by recent evidence of iron as an important determinant of pancreatic islet inflammation and as a biomarker of diabetes risk and mortality. The iron metabolism in the β-cell is complex. Excess free iron is toxic, but at the same time, iron is required for normal β-cell function and thereby glucose homeostasis. In the pathogenesis of diabetes, iron generates reactive oxygen species (ROS) by participating in the Fenton chemistry, which can induce oxidative damage and apoptosis. The aim of this review is to present and discuss recent evidence, suggesting that iron is a key pathogenic factor in both type 1 and type 2 diabetes with a focus on inflammatory pathways. Pro-inflammatory cytokine-induced β-cell death is not fully understood, but may include iron-induced ROS formation resulting in dedifferentiation by activation of transcription factors, activation of the mitochondrial apoptotic machinery or of other cell death mechanisms. The pro-inflammatory cytokine IL-1β facilitates divalent metal transporter 1 (DMT1)-induced β-cell iron uptake and consequently ROS formation and apoptosis, and we propose that this mechanism provides the relay between inflammation and oxidative β-cell damage. Iron chelation may be a potential therapeutic approach to reduce disease severity and mortality among diabetes patients. However, the therapeutic effect and safety of iron reduction need to be tested in clinical trials before dietary interventions or the use of iron chelation therapy titrated to avoid anaemia.
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Affiliation(s)
- J. B. Hansen
- Section for Endocrinological Research; Department of Biomedical Sciences; University of Copenhagen; Copenhagen Denmark
- Department of Physiology; University of Toronto; Toronto ON Canada
| | - I. W. Moen
- Section for Endocrinological Research; Department of Biomedical Sciences; University of Copenhagen; Copenhagen Denmark
| | - T. Mandrup-Poulsen
- Section for Endocrinological Research; Department of Biomedical Sciences; University of Copenhagen; Copenhagen Denmark
- Department of Molecular Medicine and Surgery; Karolinska Institutet; Stockholm Sweden
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