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Naatz A, Yeo CT, Hogg N, Corbett JA. β-Cell-selective regulation of gene expression by nitric oxide. Am J Physiol Regul Integr Comp Physiol 2024; 326:R552-R566. [PMID: 38586887 DOI: 10.1152/ajpregu.00240.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 03/07/2024] [Accepted: 04/02/2024] [Indexed: 04/09/2024]
Abstract
Nitric oxide is produced at low micromolar levels following the induction of inducible nitric oxide synthase (iNOS) and is responsible for mediating the inhibitory actions of cytokines on glucose-stimulated insulin secretion by islets of Langerhans. It is through the inhibition of mitochondrial oxidative metabolism, specifically aconitase and complex 4 of the electron transport chain, that nitric oxide inhibits insulin secretion. Nitric oxide also attenuates protein synthesis, induces DNA damage, activates DNA repair pathways, and stimulates stress responses (unfolded protein and heat shock) in β-cells. In this report, the time- and concentration-dependent effects of nitric oxide on the expression of six genes known to participate in the response of β-cells to this free radical were examined. The genes included Gadd45α (DNA repair), Puma (apoptosis), Hmox1 (antioxidant defense), Hsp70 (heat shock), Chop (UPR), and Ppargc1α (mitochondrial biogenesis). We show that nitric oxide stimulates β-cell gene expression in a narrow concentration range of ∼0.5-1 µM or levels corresponding to iNOS-derived nitric oxide. At concentrations greater than 1 µM, nitric oxide fails to stimulate gene expression in β-cells, and this is associated with the inhibition of mitochondrial oxidative metabolism. This narrow concentration range of responses is β-cell selective, as the actions of nitric oxide in non-β-cells (α-cells, mouse embryonic fibroblasts, and macrophages) are concentration dependent. Our findings suggest that β-cells respond to a narrow concentration range of nitric oxide that is consistent with the levels produced following iNOS induction, and that these concentration-dependent actions are selective for insulin-containing cells.
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Affiliation(s)
- Aaron Naatz
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
| | - Chay Teng Yeo
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
| | - Neil Hogg
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
| | - John A Corbett
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
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Feiveson AH, Krieger SS, von Scheven G, Crucian BE, Bürkle A, Stahn AC, Wu H, Moreno-Villanueva M. DNA Damage and Radiosensitivity in Blood Cells from Subjects Undergoing 45 Days of Isolation and Confinement: An Explorative Study. Curr Issues Mol Biol 2022; 44:654-669. [PMID: 35723331 PMCID: PMC8929106 DOI: 10.3390/cimb44020046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 01/02/2022] [Accepted: 01/16/2022] [Indexed: 11/16/2022] Open
Abstract
The effect of confined and isolated experience on astronauts’ health is an important factor to consider for future space exploration missions. The more confined and isolated humans are, the more likely they are to develop negative behavioral or cognitive conditions such as a mood decline, sleep disorder, depression, fatigue and/or physiological problems associated with chronic stress. Molecular mediators of chronic stress, such as cytokines, stress hormones or reactive oxygen species (ROS) are known to induce cellular damage including damage to the DNA. In view of the growing evidence of chronic stress-induced DNA damage, we conducted an explorative study and measured DNA strand breaks in 20 healthy adults. The participants were grouped into five teams (missions). Each team was composed of four participants, who spent 45 days in isolation and confinement in NASA’s Human Exploration Research Analog (HERA). Endogenous DNA integrity, ex-vivo radiation-induced DNA damage and the rates of DNA repair were assessed every week. Our results show a high inter-individual variability as well as differences between the missions, which cannot be explained by inter-individual variability alone. The ages and sex of the participants did not appear to influence the results.
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Affiliation(s)
- Alan H. Feiveson
- NASA Johnson Space Center, Houston, TX 77058, USA; (A.H.F.); (B.E.C.); (H.W.)
| | | | - Gudrun von Scheven
- Molecular Toxicology Group, Department of Biology, University of Konstanz, 78457 Konstanz, Germany; (G.v.S.); (A.B.)
| | - Brian E. Crucian
- NASA Johnson Space Center, Houston, TX 77058, USA; (A.H.F.); (B.E.C.); (H.W.)
| | - Alexander Bürkle
- Molecular Toxicology Group, Department of Biology, University of Konstanz, 78457 Konstanz, Germany; (G.v.S.); (A.B.)
| | - Alexander C. Stahn
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, 1019 Blockley Hall, 423 Guardian Drive, Philadelphia, PA 19104, USA;
- Center for Space Medicine and Extreme Environments, Institute of Physiology, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, 10117 Berlin, Germany
| | - Honglu Wu
- NASA Johnson Space Center, Houston, TX 77058, USA; (A.H.F.); (B.E.C.); (H.W.)
| | - María Moreno-Villanueva
- NASA Johnson Space Center, Houston, TX 77058, USA; (A.H.F.); (B.E.C.); (H.W.)
- Human Performance Research Centre, Department of Sport Science, University of Konstanz, 78457 Konstanz, Germany
- Correspondence: ; Tel.: +49-753-188-3599
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Oleson BJ, Corbett JA. Can insulin secreting pancreatic β-cells provide novel insights into the metabolic regulation of the DNA damage response? Biochem Pharmacol 2020; 176:113907. [PMID: 32171728 DOI: 10.1016/j.bcp.2020.113907] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Accepted: 03/06/2020] [Indexed: 12/18/2022]
Abstract
Insulin, produced by pancreatic β-cells, is responsible for the control of whole-body glucose metabolism. Insulin is secreted by pancreatic β-cells in a tightly regulated process that is controlled by the serum level of glucose, glucose sensing and glucose oxidative metabolism. The regulation of intermediary metabolism in β-cells is unique as these cells oxidize glucose to CO2 on substrate supply while mitochondrial oxidative metabolism occurs on demand, for the production of intermediates or energy production, in most cell types. This review discusses recent findings that the regulation of intermediary metabolism by nitric oxide attenuates the DNA damage response (DDR) and DNA damage-dependent apoptosis in a β-cell selective manner. Specific focus is placed on the mechanisms by which iNOS derived nitric oxide (low micromolar levels) regulates DDR activation via the inhibition of intermediary metabolism. The physiological significance of the association of metabolism, nitric oxide and DDR signaling for cancer biology and diabetes is discussed.
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Affiliation(s)
- Bryndon J Oleson
- From the Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - John A Corbett
- From the Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
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Oleson BJ, Corbett JA. Dual Role of Nitric Oxide in Regulating the Response of β Cells to DNA Damage. Antioxid Redox Signal 2018; 29:1432-1445. [PMID: 28978225 PMCID: PMC6166691 DOI: 10.1089/ars.2017.7351] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 09/09/2017] [Indexed: 01/09/2023]
Abstract
SIGNIFICANCE Cytokines released in and around pancreatic islets during islet inflammation are believed to contribute to impaired β cell function and β cell death during the development of diabetes. Nitric oxide, produced by β cells in response to cytokine exposure, controls many of the responses of β cells during islet inflammation. Recent Advances: Although nitric oxide has been shown to inhibit insulin secretion and oxidative metabolism and induce DNA damage in β cells, it also activates protective pathways that promote recovery of insulin secretion and oxidative metabolism and repair of damaged DNA. Recent studies have identified a novel role for nitric oxide in selectively regulating the DNA damage response in β cells. CRITICAL ISSUES Does nitric oxide mediate cytokine-induced β cell damage, or is nitric oxide produced by β cells in response to cytokines to protect β cells from damage? FUTURE DIRECTIONS β cells appear to be the only islet endocrine cell type capable of responding to proinflammatory cytokines with the production of nitric oxide, and these terminally differentiated cells have a limited capacity to regenerate. It is likely that there is a physiological purpose for this response, and understanding this could open new areas of study regarding the loss of functional β cell mass during diabetes development.
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Affiliation(s)
- Bryndon J. Oleson
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - John A. Corbett
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin
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Oleson BJ, Broniowska KA, Naatz A, Hogg N, Tarakanova VL, Corbett JA. Nitric Oxide Suppresses β-Cell Apoptosis by Inhibiting the DNA Damage Response. Mol Cell Biol 2016; 36:2067-77. [PMID: 27185882 PMCID: PMC4946431 DOI: 10.1128/mcb.00262-16] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 05/12/2016] [Indexed: 12/15/2022] Open
Abstract
Nitric oxide, produced in pancreatic β cells in response to proinflammatory cytokines, plays a dual role in the regulation of β-cell fate. While nitric oxide induces cellular damage and impairs β-cell function, it also promotes β-cell survival through activation of protective pathways that promote β-cell recovery. In this study, we identify a novel mechanism in which nitric oxide prevents β-cell apoptosis by attenuating the DNA damage response (DDR). Nitric oxide suppresses activation of the DDR (as measured by γH2AX formation and the phosphorylation of KAP1 and p53) in response to multiple genotoxic agents, including camptothecin, H2O2, and nitric oxide itself, despite the presence of DNA damage. While camptothecin and H2O2 both induce DDR activation, nitric oxide suppresses only camptothecin-induced apoptosis and not H2O2-induced necrosis. The ability of nitric oxide to suppress the DDR appears to be selective for pancreatic β cells, as nitric oxide fails to inhibit DDR signaling in macrophages, hepatocytes, and fibroblasts, three additional cell types examined. While originally described as the damaging agent responsible for cytokine-induced β-cell death, these studies identify a novel role for nitric oxide as a protective molecule that promotes β-cell survival by suppressing DDR signaling and attenuating DNA damage-induced apoptosis.
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Affiliation(s)
- Bryndon J Oleson
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | | | - Aaron Naatz
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Neil Hogg
- Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Vera L Tarakanova
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - John A Corbett
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
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Oleson BJ, McGraw JA, Broniowska KA, Annamalai M, Chen J, Bushkofsky JR, Davis DB, Corbett JA, Mathews CE. Distinct differences in the responses of the human pancreatic β-cell line EndoC-βH1 and human islets to proinflammatory cytokines. Am J Physiol Regul Integr Comp Physiol 2015; 309:R525-34. [PMID: 26084699 DOI: 10.1152/ajpregu.00544.2014] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Accepted: 06/15/2015] [Indexed: 11/22/2022]
Abstract
While insulinoma cells have been developed and proven to be extremely useful in studies focused on mechanisms controlling β-cell function and viability, translating findings to human β-cells has proven difficult because of the limited access to human islets and the absence of suitable insulinoma cell lines of human origin. Recently, a human β-cell line, EndoC-βH1, has been derived from human fetal pancreatic buds. The purpose of this study was to determine whether human EndoC-βH1 cells respond to cytokines in a fashion comparable to human islets. Unlike most rodent-derived insulinoma cell lines that respond to cytokines in a manner consistent with rodent islets, EndoC-βH1 cells fail to respond to a combination of cytokines (IL-1, IFN-γ, and TNF) in a manner consistent with human islets. Nitric oxide, produced following inducible nitric oxide synthase (iNOS) expression, is a major mediator of cytokine-induced human islet cell damage. We show that EndoC-βH1 cells fail to express iNOS or produce nitric oxide in response to this combination of cytokines. Inhibitors of iNOS prevent cytokine-induced loss of human islet cell viability; however, they do not prevent cytokine-induced EndoC-βH1 cell death. Stressed human islets or human islets expressing heat shock protein 70 (HSP70) are resistant to cytokines, and, much like stressed human islets, EndoC-βH1 cells express HSP70 under basal conditions. Elevated basal expression of HSP70 in EndoC-βH1 cells is consistent with the lack of iNOS expression in response to cytokine treatment. While expressing HSP70, EndoC-βH1 cells fail to respond to endoplasmic reticulum stress activators, such as thapsigargin. These findings indicate that EndoC-βH1 cells do not faithfully recapitulate the response of human islets to cytokines. Therefore, caution should be exercised when making conclusions regarding the actions of cytokines on human islets when using this human-derived insulinoma cell line.
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Affiliation(s)
- Bryndon J Oleson
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Jennifer A McGraw
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin
| | | | - Mani Annamalai
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida College of Medicine, Gainesville, Florida
| | - Jing Chen
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida College of Medicine, Gainesville, Florida
| | - Justin R Bushkofsky
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Wisconsin, Madison, Wisconsin; and
| | - Dawn B Davis
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Wisconsin, Madison, Wisconsin; and William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin
| | - John A Corbett
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin;
| | - Clayton E Mathews
- Department of Pathology, Immunology, and Laboratory Medicine, University of Florida College of Medicine, Gainesville, Florida
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Oleson BJ, Broniowska KA, Schreiber KH, Tarakanova VL, Corbett JA. Nitric oxide induces ataxia telangiectasia mutated (ATM) protein-dependent γH2AX protein formation in pancreatic β cells. J Biol Chem 2014; 289:11454-11464. [PMID: 24610783 PMCID: PMC4036281 DOI: 10.1074/jbc.m113.531228] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Revised: 02/20/2014] [Indexed: 02/06/2023] Open
Abstract
In this study, the effects of cytokines on the activation of the DNA double strand break repair factors histone H2AX (H2AX) and ataxia telangiectasia mutated (ATM) were examined in pancreatic β cells. We show that cytokines stimulate H2AX phosphorylation (γH2AX formation) in rat islets and insulinoma cells in a nitric oxide- and ATM-dependent manner. In contrast to the well documented role of ATM in DNA repair, ATM does not appear to participate in the repair of nitric oxide-induced DNA damage. Instead, nitric oxide-induced γH2AX formation correlates temporally with the onset of irreversible DNA damage and the induction of apoptosis. Furthermore, inhibition of ATM attenuates cytokine-induced caspase activation. These findings show that the formation of DNA double strand breaks correlates with ATM activation, irreversible DNA damage, and ATM-dependent induction of apoptosis in cytokine-treated β cells.
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Affiliation(s)
- Bryndon J Oleson
- Department of Biochemistry and Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | | | - Katherine H Schreiber
- Edward A. Doisy Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, Missouri 63104
| | - Vera L Tarakanova
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 and
| | - John A Corbett
- Department of Biochemistry and Medical College of Wisconsin, Milwaukee, Wisconsin 53226.
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Abstract
Autoimmune diabetes is characterized by the selective destruction of insulin-secreting β-cells that occurs during an inflammatory reaction in and around pancreatic islets of Langerhans. Cytokines such as interleukin-1, released by activated immune cells, have been shown to inhibit insulin secretion from pancreatic β-cells and cause islet destruction. In response to cytokines, β-cells express inducible nitric oxide synthase and produce micromolar levels of the free radical nitric oxide. Nitric oxide inhibits the mitochondrial oxidation of glucose resulting in an impairment of insulin secretion. Nitric oxide is also responsible for cytokine-mediated DNA damage in β-cells. While nitric oxide mediates the inhibitory and toxic effects of cytokines, it also activates protective pathways that allow β-cells to recover from this damage. This review will focus on the dual role of nitric oxide as a mediator of cytokine-induced damage and the activator of repair mechanisms that protect β-cells from cytokine-mediated injury.
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Affiliation(s)
| | - Bryndon J Oleson
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - John A Corbett
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
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Padgett LE, Broniowska KA, Hansen PA, Corbett JA, Tse HM. The role of reactive oxygen species and proinflammatory cytokines in type 1 diabetes pathogenesis. Ann N Y Acad Sci 2013; 1281:16-35. [PMID: 23323860 PMCID: PMC3715103 DOI: 10.1111/j.1749-6632.2012.06826.x] [Citation(s) in RCA: 192] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Type 1 diabetes (T1D) is a T cell–mediated autoimmune disease characterized by the destruction of insulin-secreting pancreatic β cells. In humans with T1D and in nonobese diabetic (NOD) mice (a murine model for human T1D), autoreactive T cells cause β-cell destruction, as transfer or deletion of these cells induces or prevents disease, respectively. CD4+ and CD8+ T cells use distinct effector mechanisms and act at different stages throughout T1D to fuel pancreatic β-cell destruction and disease pathogenesis. While these adaptive immune cells employ distinct mechanisms for β-cell destruction, one central means for enhancing their autoreactivity is by the secretion of proinflammatory cytokines, such as IFN-γ, TNF-α, and IL-1. In addition to their production by diabetogenic T cells, proinflammatory cytokines are induced by reactive oxygen species (ROS) via redox-dependent signaling pathways. Highly reactive molecules, proinflammatory cytokines are produced upon lymphocyte infiltration into pancreatic islets and induce disease pathogenicity by directly killing β cells, which characteristically possess low levels of antioxidant defense enzymes. In addition to β-cell destruction, proinflammatory cytokines are necessary for efficient adaptive immune maturation, and in the context of T1D they exacerbate autoimmunity by intensifying adaptive immune responses. The first half of this review discusses the mechanisms by which autoreactive T cells induce T1D pathogenesis and the importance of ROS for efficient adaptive immune activation, which, in the context of T1D, exacerbates autoimmunity. The second half provides a comprehensive and detailed analysis of (1) the mechanisms by which cytokines such as IL-1 and IFN-γ influence islet insulin secretion and apoptosis and (2) the key free radicals and transcription factors that control these processes.
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Affiliation(s)
- Lindsey E Padgett
- Department of Microbiology, Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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Hughes KJ, Meares GP, Hansen PA, Corbett JA. FoxO1 and SIRT1 regulate beta-cell responses to nitric oxide. J Biol Chem 2011; 286:8338-8348. [PMID: 21196578 DOI: 10.1074/jbc.m110.204768] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
For many cell types, including pancreatic β-cells, nitric oxide is a mediator of cell death; paradoxically, nitric oxide can also activate pathways that promote the repair of cellular damage. In this report, a role for FoxO1-dependent transcriptional activation and its regulation by SIRT1 in determining the cellular response to nitric oxide is provided. In response to nitric oxide, FoxO1 translocates from the cytoplasm to the nucleus and stimulates the expression of the DNA repair gene GADD45α, resulting in FoxO1-dependent DNA repair. FoxO1-dependent gene expression appears to be regulated by the NAD(+)-dependent deacetylase SIRT1. In response to SIRT1 inhibitors, the FoxO1-dependent protective actions of nitric oxide (GADD45α expression and DNA repair) are attenuated, and FoxO1 activates a proapoptotic program that includes PUMA (p53-up-regulated mediator of apoptosis) mRNA accumulation and caspase-3 cleavage. These findings support primary roles for FoxO1 and SIRT1 in regulating the cellular responses of β-cells to nitric oxide.
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Affiliation(s)
- Katherine J Hughes
- From the Edward A. Doisy Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, Missouri 63104
| | - Gordon P Meares
- the Comprehensive Diabetes Center, Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham, Birmingham, Alabama 35294, and
| | - Polly A Hansen
- the Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226
| | - John A Corbett
- the Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226.
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Hughes KJ, Meares GP, Chambers KT, Corbett JA. Repair of nitric oxide-damaged DNA in beta-cells requires JNK-dependent GADD45alpha expression. J Biol Chem 2009; 284:27402-8. [PMID: 19648647 DOI: 10.1074/jbc.m109.046912] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Proinflammatory cytokines induce nitric oxide-dependent DNA damage and ultimately beta-cell death. Not only does nitric oxide cause beta-cell damage, it also activates a functional repair process. In this study, the mechanisms activated by nitric oxide that facilitate the repair of damaged beta-cell DNA are examined. JNK plays a central regulatory role because inhibition of this kinase attenuates the repair of nitric oxide-induced DNA damage. p53 is a logical target of JNK-dependent DNA repair; however, nitric oxide does not stimulate p53 activation or accumulation in beta-cells. Further, knockdown of basal p53 levels does not affect DNA repair. In contrast, expression of growth arrest and DNA damage (GADD) 45alpha, a DNA repair gene that can be regulated by p53-dependent and p53-independent pathways, is stimulated by nitric oxide in a JNK-dependent manner, and knockdown of GADD45alpha expression attenuates the repair of nitric oxide-induced beta-cell DNA damage. These findings show that beta-cells have the ability to repair nitric oxide-damaged DNA and that JNK and GADD45alpha mediate the p53-independent repair of this DNA damage.
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Affiliation(s)
- Katherine J Hughes
- Edward A. Doisy Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, Missouri 63104, USA
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Campbell SC, Richardson H, Ferris WF, Butler CS, Macfarlane WM. Nitric oxide stimulates insulin gene transcription in pancreatic β-cells. Biochem Biophys Res Commun 2007; 353:1011-6. [PMID: 17210120 DOI: 10.1016/j.bbrc.2006.12.127] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2006] [Accepted: 12/17/2006] [Indexed: 12/15/2022]
Abstract
Recent studies have identified a positive role for nitric oxide (NO) in the regulation of pancreatic beta-cell function. The aim of this study was to determine the effects of short-term exposure to NO on beta-cell gene expression and the activity of the transcription factor PDX-1. NO stimulated the activity of the insulin gene promoter in Min6 beta-cells and endogenous insulin mRNA levels in both Min6 and isolated islets of Langerhans. Addition of wortmannin prior to NO stimulation blocked the observed increases in insulin gene promoter activity. Although NO addition stimulated the phosphorylation of p38, inhibition by SB203580 did not block the effect of NO on the insulin gene promoter. NO addition also stimulated both the nuclear accumulation and the DNA binding activity of PDX-1. This study has shown that over 24h, NO stimulates insulin gene expression, PI-3-kinase activity and the activity of the critical beta-cell transcription factor PDX-1.
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Affiliation(s)
- S C Campbell
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, UK.
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