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Park JH, Mortaja M, Son HG, Zhao X, Sloat LM, Azin M, Wang J, Collier MR, Tummala KS, Mandinova A, Bardeesy N, Semenov YR, Mino-Kenudson M, Demehri S. Statin prevents cancer development in chronic inflammation by blocking interleukin 33 expression. Nat Commun 2024; 15:4099. [PMID: 38816352 PMCID: PMC11139893 DOI: 10.1038/s41467-024-48441-8] [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: 04/20/2023] [Accepted: 04/24/2024] [Indexed: 06/01/2024] Open
Abstract
Chronic inflammation is a major cause of cancer worldwide. Interleukin 33 (IL-33) is a critical initiator of cancer-prone chronic inflammation; however, its induction mechanism by environmental causes of chronic inflammation is unknown. Herein, we demonstrate that Toll-like receptor (TLR)3/4-TBK1-IRF3 pathway activation links environmental insults to IL-33 induction in the skin and pancreas inflammation. An FDA-approved drug library screen identifies pitavastatin to effectively suppress IL-33 expression by blocking TBK1 membrane recruitment/activation through the mevalonate pathway inhibition. Accordingly, pitavastatin prevents chronic pancreatitis and its cancer sequela in an IL-33-dependent manner. The IRF3-IL-33 axis is highly active in chronic pancreatitis and its associated pancreatic cancer in humans. Interestingly, pitavastatin use correlates with a significantly reduced risk of chronic pancreatitis and pancreatic cancer in patients. Our findings demonstrate that blocking the TBK1-IRF3-IL-33 signaling axis suppresses cancer-prone chronic inflammation. Statins present a safe and effective prophylactic strategy to prevent chronic inflammation and its cancer sequela.
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Affiliation(s)
- Jong Ho Park
- Center for Cancer Immunology, Krantz Family Center for Cancer Research, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Cutaneous Biology Research Center, Department of Dermatology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Department of Anatomy, School of Medicine, Keimyung University, Daegu, South Korea
| | - Mahsa Mortaja
- Center for Cancer Immunology, Krantz Family Center for Cancer Research, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Cutaneous Biology Research Center, Department of Dermatology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Heehwa G Son
- Center for Cancer Immunology, Krantz Family Center for Cancer Research, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Cutaneous Biology Research Center, Department of Dermatology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Xutu Zhao
- Center for Cancer Immunology, Krantz Family Center for Cancer Research, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Cutaneous Biology Research Center, Department of Dermatology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Lauren M Sloat
- Center for Cancer Immunology, Krantz Family Center for Cancer Research, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Cutaneous Biology Research Center, Department of Dermatology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Marjan Azin
- Center for Cancer Immunology, Krantz Family Center for Cancer Research, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Cutaneous Biology Research Center, Department of Dermatology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Jun Wang
- Cutaneous Biology Research Center, Department of Dermatology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Michael R Collier
- Department of Dermatology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Krishna S Tummala
- Krantz Family Center for Cancer Research, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Center for Regenerative Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Medicine, Harvard Medical School, Boston, MA, USA
- Cancer Program, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA, USA
- Quantitative Biosciences, Merck Research Laboratories, Boston, MA, USA
| | - Anna Mandinova
- Cutaneous Biology Research Center, Department of Dermatology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Nabeel Bardeesy
- Krantz Family Center for Cancer Research, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Center for Regenerative Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Medicine, Harvard Medical School, Boston, MA, USA
- Cancer Program, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA, USA
| | - Yevgeniy R Semenov
- Department of Dermatology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Laboratory of Systems Pharmacology, Harvard Program in Therapeutic Science, Harvard Medical School, Boston, USA
| | - Mari Mino-Kenudson
- Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Shadmehr Demehri
- Center for Cancer Immunology, Krantz Family Center for Cancer Research, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
- Cutaneous Biology Research Center, Department of Dermatology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
- Department of Dermatology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
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Lee YT, Mohd Yunus MH, Yazid MD, Ugusman A. Unraveling the path to osteoarthritis management: targeting chondrocyte apoptosis for therapeutic intervention. Front Cell Dev Biol 2024; 12:1347126. [PMID: 38827524 PMCID: PMC11140145 DOI: 10.3389/fcell.2024.1347126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 05/06/2024] [Indexed: 06/04/2024] Open
Abstract
Osteoarthritis (OA) is a chronic disease affecting joints and further causing disabilities. This disease affects around 240 million people worldwide. It is a multifactorial disease, and its etiology is difficult to determine. Although numerous therapeutic strategies are available, the therapies are aimed at reducing pain and improving patients' quality of life. Hence, there is an urgent need to develop disease-modifying drugs (DMOAD) that can reverse or halt OA progression. Apoptosis is a cell removal process that is important in maintaining homeostatic mechanisms in the development and sustaining cell population. The apoptosis of chondrocytes is believed to play an important role in OA progression due to poor chondrocytes self-repair abilities to maintain the extracellular matrix (ECM). Hence, targeting chondrocyte apoptosis can be one of the potential therapeutic strategies in OA management. There are various mediators and targets available to inhibit apoptosis such as autophagy, endoplasmic reticulum (ER) stress, oxidative stress, and inflammation. As such, this review highlights the importance and potential targets that can be aimed to reduce chondrocyte apoptosis.
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Affiliation(s)
- Yi Ting Lee
- Department of Physiology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Cheras, Malaysia
| | - Mohd Heikal Mohd Yunus
- Department of Physiology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Cheras, Malaysia
| | - Muhammad Dain Yazid
- Centre for Tissue Engineering and Regenerative Medicine, Faculty of Medicine, Universiti Kebangsaan Malaysia, Cheras, Malaysia
| | - Azizah Ugusman
- Department of Physiology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Cheras, Malaysia
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Chaudhary R, Khanna J, Rohilla M, Gupta S, Bansal S. Investigation of Pancreatic-beta Cells Role in the Biological Process of Ageing. Endocr Metab Immune Disord Drug Targets 2024; 24:348-362. [PMID: 37608675 DOI: 10.2174/1871530323666230822095932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 06/27/2023] [Accepted: 07/20/2023] [Indexed: 08/24/2023]
Abstract
BACKGROUND Cellular senescence is associated with the formation and progression of a range of illnesses, including ageing and metabolic disorders such as diabetes mellitus and pancreatic beta cell dysfunction. Ageing and reduced glucose tolerance are interconnected. Often, Diabetes is becoming more common, which is concerning since it raises the risk of a variety of age-dependent disorders such as cardiovascular disease, cancer, Parkinson's disease, stroke, and Alzheimer's disease. OBJECTIVES The objectives of this study are to find out the most recent research on how ageing affects the functions of pancreatic beta cells, beta cell mass, beta cell senescence, mitochondrial dysfunction, and hormonal imbalance. METHODS Various research and review manuscripts are gathered from various records such as Google Scholar, PubMed, Mendeley, Scopus, Science Open, the Directory of Open Access Journals, and the Education Resources Information Centre, using different terms like "Diabetes, cellular senescence, beta cells, ageing, insulin, glucose". RESULTS In this review, we research novel targets in order to discover new strategies to treat diabetes. Abnormal glucose homeostasis and type 2 diabetes mellitus in the elderly may aid in the development of novel medicines to delay or prevent diabetes onset, improve quality of life, and, finally, increase life duration. CONCLUSION Aging accelerates beta cell senescence by generating premature cell senescence, which is mostly mediated by high glucose levels. Despite higher plasma glucose levels, hepatic gluconeogenesis accelerates and adipose tissue lipolysis rises, resulting in an increase in free fatty acid levels in the blood and worsening insulin resistance throughout the body.
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Affiliation(s)
- Rishabh Chaudhary
- Department of Pharmacology, M. M. College of Pharmacy, Maharishi Markandeshwar (Deemed to be University), Mullana, Ambala, Haryana, 133206, India
| | - Janvi Khanna
- Department of Pharmacology, M. M. College of Pharmacy, Maharishi Markandeshwar (Deemed to be University), Mullana, Ambala, Haryana, 133206, India
| | - Manni Rohilla
- Department of Pharmacology, M. M. College of Pharmacy, Maharishi Markandeshwar (Deemed to be University), Mullana, Ambala, Haryana, 133206, India
- Department of Pharmacology, Chitkara College of Pharmacy, Chitkara University, Rajpura, Punjab, 140401, India
| | - Sumeet Gupta
- Department of Pharmacology, M. M. College of Pharmacy, Maharishi Markandeshwar (Deemed to be University), Mullana, Ambala, Haryana, 133206, India
| | - Seema Bansal
- Department of Pharmacology, M. M. College of Pharmacy, Maharishi Markandeshwar (Deemed to be University), Mullana, Ambala, Haryana, 133206, India
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Azarova I, Polonikov A, Klyosova E. Molecular Genetics of Abnormal Redox Homeostasis in Type 2 Diabetes Mellitus. Int J Mol Sci 2023; 24:ijms24054738. [PMID: 36902173 PMCID: PMC10003739 DOI: 10.3390/ijms24054738] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 02/20/2023] [Accepted: 02/24/2023] [Indexed: 03/05/2023] Open
Abstract
Numerous studies have shown that oxidative stress resulting from an imbalance between the production of free radicals and their neutralization by antioxidant enzymes is one of the major pathological disorders underlying the development and progression of type 2 diabetes (T2D). The present review summarizes the current state of the art advances in understanding the role of abnormal redox homeostasis in the molecular mechanisms of T2D and provides comprehensive information on the characteristics and biological functions of antioxidant and oxidative enzymes, as well as discusses genetic studies conducted so far in order to investigate the contribution of polymorphisms in genes encoding redox state-regulating enzymes to the disease pathogenesis.
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Affiliation(s)
- Iuliia Azarova
- Department of Biological Chemistry, Kursk State Medical University, 3 Karl Marx Street, 305041 Kursk, Russia
- Laboratory of Biochemical Genetics and Metabolomics, Research Institute for Genetic and Molecular Epidemiology, Kursk State Medical University, 18 Yamskaya Street, 305041 Kursk, Russia
| | - Alexey Polonikov
- Laboratory of Statistical Genetics and Bioinformatics, Research Institute for Genetic and Molecular Epidemiology, Kursk State Medical University, 18 Yamskaya Street, 305041 Kursk, Russia
- Department of Biology, Medical Genetics and Ecology, Kursk State Medical University, 3 Karl Marx Street, 305041 Kursk, Russia
- Correspondence:
| | - Elena Klyosova
- Laboratory of Biochemical Genetics and Metabolomics, Research Institute for Genetic and Molecular Epidemiology, Kursk State Medical University, 18 Yamskaya Street, 305041 Kursk, Russia
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Elumalai S, Karunakaran U, Won KC, Chung SM, Moon JS. Perfluorooctane sulfonate-induced oxidative stress contributes to pancreatic β-cell apoptosis by inhibiting cyclic adenosine monophosphate pathway: Prevention by pentoxifylline. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 320:120959. [PMID: 36621715 DOI: 10.1016/j.envpol.2022.120959] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2022] [Revised: 12/18/2022] [Accepted: 12/26/2022] [Indexed: 06/17/2023]
Abstract
Endocrine-disrupting chemical perfluorooctane sulfonate (PFOS) acute exposure stimulates insulin secretion from pancreatic β-cells. However, chronic exposure to PFOS on pancreatic β-cells, its role in insulin secretion, and the underlying mechanisms have not been studied. We used rat insulinoma INS-1 and human 1.1b4 islet cells to investigate the chronic effects of PFOS on glucose-stimulated insulin secretion and toxicity implicated in the downregulation of β-cell functionality. Chronic exposure of INS-1 cells or human pancreatic 1.1b4 β-cells to PFOS stimulated the small G-protein RAC1-guanosine triphosphate-dependent nicotinamide adenine dinucleotide phosphate oxidase (NOX2/gp91phox) subunit expression and activation. Upregulated NOX2/gp91phox activation led to elevated reactive oxygen species (ROS) production with a decrease in the cyclic adenosine monophosphate/protein kinase A (cAMP/PKA) pathway in both cell types. Inhibition of cAMP/PKA signaling induces β-cell mitochondrial dysfunction and endoplasmic stress via the loss of PDX1-SERCA2B and glucose-stimulated insulin release. Inhibiting RAC1-NOX2/gp91phox activation or elevating cAMP by pentoxifylline, a Food and Drug Administration-approved phosphodiesterase inhibitor, significantly reduced PFOS-induced ROS production and restored insulin secretory function of pancreatic β-cells. Enhanced secretory function in pentoxifylline-treated cells was associated with increased stability of PDX1-SERCA2B protein levels. Intriguingly, inhibition of cAMP/PKA signaling impaired pentoxifylline-induced insulin secretion caused by the activation of ROS production and mitochondrial dysfunction. Overall, our findings show that PFOS has a new and first-ever direct chronic effect on pancreatic β-cell failure through increased RAC1-NOX2/gp91phox activation and pentoxifylline-induced cAMP/PKA signaling, which inhibits PFOS-mediated mitochondrial dysfunction.
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Affiliation(s)
- Suma Elumalai
- Innovative Center for Aging Research, Yeungnam University Medical Center, Daegu, Republic of Korea
| | - Udayakumar Karunakaran
- Innovative Center for Aging Research, Yeungnam University Medical Center, Daegu, Republic of Korea
| | - Kyu Chang Won
- Innovative Center for Aging Research, Yeungnam University Medical Center, Daegu, Republic of Korea; Department of Internal Medicine, Yeungnam University College of Medicine, Daegu, Republic of Korea
| | - Seung Min Chung
- Innovative Center for Aging Research, Yeungnam University Medical Center, Daegu, Republic of Korea; Department of Internal Medicine, Yeungnam University College of Medicine, Daegu, Republic of Korea
| | - Jun Sung Moon
- Department of Internal Medicine, Yeungnam University College of Medicine, Daegu, Republic of Korea.
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Stancill JS, Corbett JA. Hydrogen peroxide detoxification through the peroxiredoxin/thioredoxin antioxidant system: A look at the pancreatic β-cell oxidant defense. VITAMINS AND HORMONES 2022; 121:45-66. [PMID: 36707143 PMCID: PMC10058777 DOI: 10.1016/bs.vh.2022.11.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Reactive oxygen species (ROS), such as hydrogen peroxide, are formed when molecular oxygen obtains additional electrons, increasing its reactivity. While low concentrations of hydrogen peroxide are necessary for regulation of normal cellular signaling events, high concentrations can be toxic. To maintain this balance between beneficial and deleterious concentrations of hydrogen peroxide, cells utilize antioxidants. Our recent work supports a primary role for peroxiredoxin, thioredoxin, and thioredoxin reductase as the oxidant defense pathway used by insulin-producing pancreatic β-cells. These three players work in an antioxidant cycle based on disulfide exchange, with oxidized targets ultimately being reduced using electrons provided by NADPH. Peroxiredoxins also participate in hydrogen peroxide-based signaling through disulfide exchange with redox-regulated target proteins. This chapter will describe the catalytic mechanisms of thioredoxin, thioredoxin reductase, and peroxiredoxin and provide an in-depth look at the roles these enzymes play in antioxidant defense pathways of insulin-secreting β-cells. Finally, we will evaluate the physiological relevance of peroxiredoxin-mediated hydrogen peroxide signaling as a regulator of β-cell function.
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Affiliation(s)
- Jennifer S Stancill
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI, United States
| | - John A Corbett
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI, United States.
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Azarova I, Klyosova E, Polonikov A. Association between RAC1 gene variation, redox homeostasis and type 2 diabetes mellitus. Eur J Clin Invest 2022; 52:e13792. [PMID: 35416295 DOI: 10.1111/eci.13792] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 04/11/2022] [Indexed: 11/30/2022]
Abstract
BACKGROUND Increased production of reactive oxygen species (ROS) and oxidative stress are known to play a key role in the pathogenesis of type 2 diabetes (T2D); however, the relationship between genes encoding a multi-subunit ROS-generated enzyme NADPH oxidase and disease susceptibility remains unexplored. AIMS The present pilot study investigated whether single-nucleotide polymorphisms (SNP) at the RAC1 gene (Rac family small GTPase 1), a molecular switcher of NADPH oxidase, are associated with the risk of T2D, glucose metabolism and redox homeostasis. MATERIALS & METHODS DNA samples from 3206 unrelated Russian subjects (1579 T2D patients and 1627 controls) were genotyped for six common SNPs rs4724800, rs7784465, rs10951982, rs10238136, rs836478 and rs9374 of RAC1 using the MassArray-4 system. RESULTS SNP rs7784465 was associated with an increased risk of T2D (p = .0003), and significant differences in the RAC1 haplotypes occurred between the cases and controls (p = .005). Seventeen combinations of RAC1 genotypes showed significant associations with T2D risk (FDR <0.05). Associations of RAC1 polymorphisms with T2D were modified by environmental factors such as sedentary lifestyle, psychological stresses, a dietary deficit of fresh fruits/vegetables and increased carbohydrate intake. RAC1 polymorphisms were associated with biochemical parameters in diabetics: rs7784465 (p = .015) and rs836478 (p = .028) with increased glycated haemoglobin, rs836478 (p = .005) with increased fasting blood glucose, oxidized glutathione (p = .012) and uric acid (p = .034). Haplotype rs4724800A-rs7784465C-rs10951982G-rs10238136A-rs836478C-rs9374G was strongly associated with increased levels of hydrogen peroxide (p < .0001). CONCLUSION Thus, polymorphisms in the RAC1 gene represent novel genetic markers of type 2 diabetes, and their link with glucose metabolism and disease pathogenesis is associated with the changes in redox homeostasis.
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Affiliation(s)
- Iuliia Azarova
- Department of Biological Chemistry, Kursk State Medical University, Kursk, Russian Federation.,Laboratory of Biochemical Genetics and Metabolomics, Research Institute for Genetic and Molecular Epidemiology, Kursk State Medical University, Kursk, Russian Federation
| | - Elena Klyosova
- Laboratory of Biochemical Genetics and Metabolomics, Research Institute for Genetic and Molecular Epidemiology, Kursk State Medical University, Kursk, Russian Federation
| | - Alexey Polonikov
- Department of Biology, Medical Genetics and Ecology, Kursk State Medical University, Kursk, Russian Federation.,Laboratory of Statistical Genetics and Bioinformatics, Research Institute for Genetic and Molecular Epidemiology, Kursk State Medical University, Kursk, Russian Federation
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Gamage S, Hali M, Chen F, Kowluru A. CARD9 Mediates Pancreatic Islet Beta-Cell Dysfunction Under the Duress of Hyperglycemic Stress. Cell Physiol Biochem 2022; 56:120-137. [PMID: 35362297 PMCID: PMC9150799 DOI: 10.33594/000000508] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/11/2022] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND/AIMS Published evidence implicates Caspase recruitment domain containing protein 9 (CARD9) in innate immunity. Given its recently suggested roles in obesity and insulin resistance, we investigated its regulatory role(s) in the onset of islet beta cell dysfunction under chronic hyperglycemic (metabolic stress) conditions. METHODS Islets from mouse pancreas were isolated by the collagenase digestion method. Expression of CARD9 was suppressed in INS-1 832/13 cells by siRNA transfection using the DharmaFect1 reagent. The degree of activation of Rac1 was assessed by a pull-down assay kit. Interactions between CARD9, RhoGDIβ and Rac1 under metabolic stress conditions were determined by co-immunoprecipitation assay. The degree of phosphorylation of stress kinases was assessed using antibodies directed against phosphorylated forms of the respective kinases. RESULTS CARD9 expression is significantly increased following exposure to high glucose, not to mannitol (both at 20 mM; 24 hrs.) in INS-1 832/13 cells. siRNA-mediated knockdown of CARD9 significantly attenuated high glucose-induced activation of Rac1 and phosphorylation of p38MAPK and p65 subunit of NF-κB (RelA), without significantly impacting high glucose-induced effects on JNK1/2 and ERK1/2 activities. CARD9 depletion also suppressed high glucose-induced CHOP expression (a marker for endoplasmic reticulum stress) in these cells. Co-immunoprecipitation studies revealed increased association between CARD9-RhoGDIβ and decreased association between RhoGDIβ-Rac1 in cells cultured under high glucose conditions. CONCLUSION Based on these data, we conclude that CARD9 regulates activation of Rac1-p38MAPK-NFκB signaling pathway leading to functional abnormalities in beta cells under metabolic stress conditions.
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Affiliation(s)
- Suhadinie Gamage
- Biomedical Research Service, John D. Dingell VA Medical Center, Detroit, MI, USA
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, USA
| | - Mirabela Hali
- Biomedical Research Service, John D. Dingell VA Medical Center, Detroit, MI, USA
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, USA
| | - Fei Chen
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, USA
- Stony Brook Cancer Center, and Department of Pathology, Stony Brook University, Stony Brook, NY, USA
| | - Anjaneyulu Kowluru
- Biomedical Research Service, John D. Dingell VA Medical Center, Detroit, MI, USA,
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, MI, USA
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9
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Rohli KE, Boyer CK, Blom SE, Stephens SB. Nutrient Regulation of Pancreatic Islet β-Cell Secretory Capacity and Insulin Production. Biomolecules 2022; 12:335. [PMID: 35204835 PMCID: PMC8869698 DOI: 10.3390/biom12020335] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 02/16/2022] [Accepted: 02/17/2022] [Indexed: 01/27/2023] Open
Abstract
Pancreatic islet β-cells exhibit tremendous plasticity for secretory adaptations that coordinate insulin production and release with nutritional demands. This essential feature of the β-cell can allow for compensatory changes that increase secretory output to overcome insulin resistance early in Type 2 diabetes (T2D). Nutrient-stimulated increases in proinsulin biosynthesis may initiate this β-cell adaptive compensation; however, the molecular regulators of secretory expansion that accommodate the increased biosynthetic burden of packaging and producing additional insulin granules, such as enhanced ER and Golgi functions, remain poorly defined. As these adaptive mechanisms fail and T2D progresses, the β-cell succumbs to metabolic defects resulting in alterations to glucose metabolism and a decline in nutrient-regulated secretory functions, including impaired proinsulin processing and a deficit in mature insulin-containing secretory granules. In this review, we will discuss how the adaptative plasticity of the pancreatic islet β-cell's secretory program allows insulin production to be carefully matched with nutrient availability and peripheral cues for insulin signaling. Furthermore, we will highlight potential defects in the secretory pathway that limit or delay insulin granule biosynthesis, which may contribute to the decline in β-cell function during the pathogenesis of T2D.
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Affiliation(s)
- Kristen E. Rohli
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52242, USA; (K.E.R.); (C.K.B.); (S.E.B.)
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Cierra K. Boyer
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52242, USA; (K.E.R.); (C.K.B.); (S.E.B.)
- Department of Neuroscience and Pharmacology, University of Iowa, Iowa City, IA 52242, USA
| | - Sandra E. Blom
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52242, USA; (K.E.R.); (C.K.B.); (S.E.B.)
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Samuel B. Stephens
- Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA 52242, USA; (K.E.R.); (C.K.B.); (S.E.B.)
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA
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Cao Y, Wang W, Zhan X, Zhang Y. PRDX6: A protein bridging S-palmitoylation and diabetic neuropathy. Front Endocrinol (Lausanne) 2022; 13:992875. [PMID: 36120430 PMCID: PMC9478578 DOI: 10.3389/fendo.2022.992875] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 08/11/2022] [Indexed: 11/13/2022] Open
Abstract
Diabetic neuropathy is regarded as one of the most debilitating outcomes of diabetes. It can affect both the peripheral and central nervous systems, leading to pain, decreased motility, cognitive decline, and dementia. S-palmitoylation is a reversible posttranslational lipid modification, and its dysregulation has been implicated in metabolic syndrome, cancers, neurological disorders, and infections. However, the role of S-palmitoylation in diabetic neuropathy remains unclear. Here we demonstrate a potential association between activating protein palmitoylation and diabetic neuropathy. We compared the proteomic data of lumbar dorsal root ganglia (DRG) of diabetes mice and palmitoylome profiling data of the HUVEC cell line. The mapping results identified peroxiredoxin-6 (PRDX6) as a novel target in diabetic neuropathy, whose biological mechanism was associated with S-palmitoylation. Bioinformatic prediction revealed that PRDX6 had two palmitoylation sites, Cys47 and Cys91. Immunofluorescence results indicated PRDX6 translocating between the cytoplasm and cell membrane. Protein function analysis proposed that increased palmitoylation could competitively inhibit the formation of disulfide-bond between Cys47 and Cys91 and change the spatial topology of PRDX6 protein. Cl-HCO3- anion exchanger 3 (AE3) was one of the AE family members, which was proved to express in DRG. AE3 activity evoked Cl- influx in neurons which was generally associated with increased excitability and susceptibility to pain. We demonstrated that the S-palmitoylation status of Cys47 could affect the interaction between PRDX6 and the C-terminal domain of AE3, thereby regulating the activity of AE3 anion exchanger enzyme in the nervous system. The results highlight a central role for PRDX6 palmitoylation in protection against diabetic neuropathy.
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Affiliation(s)
- Yan Cao
- Department of Anesthesiology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China
| | - Wantao Wang
- Department of Spine Surgery, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China
| | - Xiaorong Zhan
- Department of Endocrinology, Southern University of Science and Technology Hospital, Shenzhen, China
| | - Yitong Zhang
- School of Life Science, Beijing Institute of Technology, Beijing, China
- *Correspondence: Yitong Zhang,
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Ahmed MM, Johnson NR, Boyd TD, Coughlan C, Chial HJ, Potter H. Innate Immune System Activation and Neuroinflammation in Down Syndrome and Neurodegeneration: Therapeutic Targets or Partners? Front Aging Neurosci 2021; 13:718426. [PMID: 34603007 PMCID: PMC8481947 DOI: 10.3389/fnagi.2021.718426] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 08/16/2021] [Indexed: 12/24/2022] Open
Abstract
Innate immune system activation and inflammation are associated with and may contribute to clinical outcomes in people with Down syndrome (DS), neurodegenerative diseases such as Alzheimer's disease (AD), and normal aging. In addition to serving as potential diagnostic biomarkers, innate immune system activation and inflammation may play a contributing or causal role in these conditions, leading to the hypothesis that effective therapies should seek to dampen their effects. However, recent intervention studies with the innate immune system activator granulocyte-macrophage colony-stimulating factor (GM-CSF) in animal models of DS, AD, and normal aging, and in an AD clinical trial suggest that activating the innate immune system and inflammation may instead be therapeutic. We consider evidence that DS, AD, and normal aging are accompanied by innate immune system activation and inflammation and discuss whether and when during the disease process it may be therapeutically beneficial to suppress or promote such activation.
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Affiliation(s)
- Md. Mahiuddin Ahmed
- Department of Neurology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
- University of Colorado Alzheimer’s and Cognition Center, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
- Linda Crnic Institute for Down Syndrome, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Noah R. Johnson
- Department of Neurology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
- University of Colorado Alzheimer’s and Cognition Center, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
- Linda Crnic Institute for Down Syndrome, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Timothy D. Boyd
- Department of Neurology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
- University of Colorado Alzheimer’s and Cognition Center, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
- Partner Therapeutics, Inc., Lexington, MA, United States
| | - Christina Coughlan
- Department of Neurology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
- University of Colorado Alzheimer’s and Cognition Center, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
- Linda Crnic Institute for Down Syndrome, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Heidi J. Chial
- Department of Neurology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
- University of Colorado Alzheimer’s and Cognition Center, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
- Linda Crnic Institute for Down Syndrome, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Huntington Potter
- Department of Neurology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
- University of Colorado Alzheimer’s and Cognition Center, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
- Linda Crnic Institute for Down Syndrome, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
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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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13
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Gendaszewska-Darmach E, Garstka MA, Błażewska KM. Targeting Small GTPases and Their Prenylation in Diabetes Mellitus. J Med Chem 2021; 64:9677-9710. [PMID: 34236862 PMCID: PMC8389838 DOI: 10.1021/acs.jmedchem.1c00410] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
![]()
A fundamental role
of pancreatic β-cells to maintain proper
blood glucose level is controlled by the Ras superfamily of small
GTPases that undergo post-translational modifications, including prenylation.
This covalent attachment with either a farnesyl or a geranylgeranyl
group controls their localization, activity, and protein–protein
interactions. Small GTPases are critical in maintaining glucose homeostasis
acting in the pancreas and metabolically active tissues such as skeletal
muscles, liver, or adipocytes. Hyperglycemia-induced upregulation
of small GTPases suggests that inhibition of these pathways deserves
to be considered as a potential therapeutic approach in treating T2D.
This Perspective presents how inhibition of various points in the
mevalonate pathway might affect protein prenylation and functioning
of diabetes-affected tissues and contribute to chronic inflammation
involved in diabetes mellitus (T2D) development. We also demonstrate
the currently available molecular tools to decipher the mechanisms
linking the mevalonate pathway’s enzymes and GTPases with diabetes.
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Affiliation(s)
- Edyta Gendaszewska-Darmach
- Institute of Molecular and Industrial Biotechnology, Faculty of Biotechnology and Food Sciences, Lodz University of Technology, Stefanowskiego Street 4/10, 90-924 Łódź, Poland
| | - Malgorzata A Garstka
- Core Research Laboratory, Department of Endocrinology, Department of Tumor and Immunology, Precision Medical Institute, Western China Science and Technology Innovation Port, School of Medicine, the Second Affiliated Hospital of Xi'an Jiaotong University, DaMingGong, Jian Qiang Road, Wei Yang district, Xi'an 710016, China
| | - Katarzyna M Błażewska
- Institute of Organic Chemistry, Faculty of Chemistry, Lodz University of Technology, Żeromskiego Street 116, 90-924 Łódź, Poland
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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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15
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Oxidative Stress in Cytokine-Induced Dysfunction of the Pancreatic Beta Cell: Known Knowns and Known Unknowns. Metabolites 2020; 10:metabo10120480. [PMID: 33255484 PMCID: PMC7759861 DOI: 10.3390/metabo10120480] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 11/18/2020] [Accepted: 11/21/2020] [Indexed: 12/12/2022] Open
Abstract
Compelling evidence from earlier studies suggests that the pancreatic beta cell is inherently weak in its antioxidant defense mechanisms to face the burden of protecting itself against the increased intracellular oxidative stress following exposure to proinflammatory cytokines. Recent evidence implicates novel roles for nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (Noxs) as contributors to the excessive intracellular oxidative stress and damage under metabolic stress conditions. This review highlights the existing evidence on the regulatory roles of at least three forms of Noxs, namely Nox1, Nox2, and Nox4, in the cascade of events leading to islet beta cell dysfunction, specifically under the duress of chronic exposure to cytokines. Potential crosstalk between key signaling pathways (e.g., inducible nitric oxide synthase [iNOS] and Noxs) in the generation and propagation of reactive molecules and metabolites leading to mitochondrial damage and cell apoptosis is discussed. Available data accrued in investigations involving small-molecule inhibitors and antioxidant protein expression methods as tools toward the prevention of cytokine-induced oxidative damage are reviewed. Lastly, current knowledge gaps in this field, and possible avenues for future research are highlighted.
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Abstract
Glucose-induced (physiological) insulin secretion from the islet β-cell involves interplay between cationic (i.e., changes in intracellular calcium) and metabolic (i.e., generation of hydrophobic and hydrophilic second messengers) events. A large body of evidence affirms support for novel regulation, by G proteins, of specific intracellular signaling events, including actin cytoskeletal remodeling, transport of insulin-containing granules to the plasma membrane for fusion, and secretion of insulin into the circulation. This article highlights the following aspects of GPCR-G protein biology of the islet. First, it overviews our current understanding of the identity of a wide variety of G protein regulators and their modulatory roles in GPCR-G protein-effector coupling, which is requisite for optimal β-cell function under physiological conditions. Second, it describes evidence in support of novel, noncanonical, GPCR-independent mechanisms of activation of G proteins in the islet. Third, it highlights the evidence indicating that abnormalities in G protein function lead to islet β-cell dysregulation and demise under the duress of metabolic stress and diabetes. Fourth, it summarizes observations of potential beneficial effects of GPCR agonists in preventing/halting metabolic defects in the islet β-cell under various pathological conditions (e.g., metabolic stress and inflammation). Lastly, it identifies knowledge gaps and potential avenues for future research in this evolving field of translational islet biology. Published 2020. Compr Physiol 10:453-490, 2020.
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Affiliation(s)
- Anjaneyulu Kowluru
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Center for Translational Research in Diabetes, Biomedical Research Service, John D. Dingell VA Medical Center, Wayne State University, Detroit, Michigan, USA
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Damacharla D, Thamilselvan V, Zhang X, Mestareehi A, Yi Z, Kowluru A. Quantitative proteomics reveals novel interaction partners of Rac1 in pancreatic β-cells: Evidence for increased interaction with Rac1 under hyperglycemic conditions. Mol Cell Endocrinol 2019; 494:110489. [PMID: 31202817 PMCID: PMC6686664 DOI: 10.1016/j.mce.2019.110489] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 06/11/2019] [Accepted: 06/11/2019] [Indexed: 11/19/2022]
Abstract
Rac1, a small G protein, regulates physiological insulin secretion from the pancreatic β-cell. Interestingly, Rac1 has also been implicated in the onset of metabolic dysfunction of the β-cell under the duress of hyperglycemia (HG). This study is aimed at the identification of interaction partners of Rac1 in β-cells under basal and HG conditions. Using co-immunoprecipitation and UPLC-ESI-MS/MS, we identified 324 Rac1 interaction partners in INS-1832/13 cells, which represent the largest Rac1 interactome to date. Furthermore, we identified 27 interaction partners that exhibited increased association with Rac1 in β-cells exposed to HG. Western blotting (INS-1832/13 cells, rat islets and human islets) and co-immunoprecipitation (INS-1832/13 cells) further validated the identity of these Rac1 interaction partners including regulators of GPCR-G protein-effector coupling in the islet. These data form the basis for future investigations on contributory roles of these Rac1-specific signaling pathways in islet β-cell function in health and diabetes.
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Affiliation(s)
- Divyasri Damacharla
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, USA
| | - Vijayalakshmi Thamilselvan
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, USA
| | - Xiangmin Zhang
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, USA
| | - Aktham Mestareehi
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, USA
| | - Zhengping Yi
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, USA
| | - Anjaneyulu Kowluru
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, USA; Center for Translational Research in Diabetes, Biomedical Research Service, John D. Dingell VA Medical Center, Detroit, MI, 48201, USA.
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18
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Møller LLV, Klip A, Sylow L. Rho GTPases-Emerging Regulators of Glucose Homeostasis and Metabolic Health. Cells 2019; 8:E434. [PMID: 31075957 PMCID: PMC6562660 DOI: 10.3390/cells8050434] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 05/02/2019] [Accepted: 05/06/2019] [Indexed: 12/11/2022] Open
Abstract
Rho guanosine triphosphatases (GTPases) are key regulators in a number of cellular functions, including actin cytoskeleton remodeling and vesicle traffic. Traditionally, Rho GTPases are studied because of their function in cell migration and cancer, while their roles in metabolism are less documented. However, emerging evidence implicates Rho GTPases as regulators of processes of crucial importance for maintaining metabolic homeostasis. Thus, the time is now ripe for reviewing Rho GTPases in the context of metabolic health. Rho GTPase-mediated key processes include the release of insulin from pancreatic β cells, glucose uptake into skeletal muscle and adipose tissue, and muscle mass regulation. Through the current review, we cast light on the important roles of Rho GTPases in skeletal muscle, adipose tissue, and the pancreas and discuss the proposed mechanisms by which Rho GTPases act to regulate glucose metabolism in health and disease. We also describe challenges and goals for future research.
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Affiliation(s)
- Lisbeth Liliendal Valbjørn Møller
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, 2100 Copenhagen Oe, Denmark.
| | - Amira Klip
- Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario M5G 0A4, Canada.
| | - Lykke Sylow
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, 2100 Copenhagen Oe, Denmark.
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19
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Foo CHJ, Pervaiz S. gRASping the redox lever to modulate cancer cell fate signaling. Redox Biol 2019; 25:101094. [PMID: 30638892 PMCID: PMC6859584 DOI: 10.1016/j.redox.2018.101094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 12/22/2018] [Accepted: 12/26/2018] [Indexed: 01/17/2023] Open
Abstract
RAS proteins are critical regulators of signaling networks controlling diverse cellular functions such as cell proliferation and survival and its mutation are among the most powerful oncogenic drivers in human cancers. Despite intense efforts, direct RAS-targeting strategies remain elusive due to its "undruggable" nature. To that end, bulk of the research efforts has been directed towards targeting upstream and/or downstream of RAS signaling. However, the therapeutic efficacies of these treatments are limited in the long run due to the acquired drug resistance in RAS-driven cancers. Interestingly, recent studies have uncovered a potential role of RAS in redox-regulation as well as the interplay between ROS and RAS-associated signaling networks during process of cancer initiation and progression. More specifically, these studies provide ample evidence to implicate RAS as a redox-rheostat, manipulating ROS levels to provide a redox-milieu conducive for carcinogenesis. Importantly, the understanding of RAS-ROS interplay could provide us with novel targetable vulnerabilities for designing therapeutic strategies. In this review, we provide a brief summary of the advances in the field to illustrate the dual role of RAS in redox-regulation and its implications in RAS signaling outcomes and also emerging redox-based strategies to target RAS-driven cancers.
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Affiliation(s)
- Chuan Han Jonathan Foo
- Department of Physiology, YLL School of Medicine, National University of Singapore (NUS), Singapore; NUS Graduate School of Integrative Sciences and Engineering, NUS, Singapore
| | - Shazib Pervaiz
- Department of Physiology, YLL School of Medicine, National University of Singapore (NUS), Singapore; Medical Science Cluster Cancer Program, YLL School of Medicine, National University of Singapore (NUS), Singapore; NUS Graduate School of Integrative Sciences and Engineering, NUS, Singapore; National University Cancer Institute, NUHS, Singapore.
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20
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Baidwan S, Chekuri A, Hynds DL, Kowluru A. Glucotoxicity promotes aberrant activation and mislocalization of Ras-related C3 botulinum toxin substrate 1 [Rac1] and metabolic dysfunction in pancreatic islet β-cells: reversal of such metabolic defects by metformin. Apoptosis 2018; 22:1380-1393. [PMID: 28828705 DOI: 10.1007/s10495-017-1409-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Emerging evidence suggests that long-term exposure of insulin-secreting pancreatic β-cells to hyperglycemic (HG; glucotoxic) conditions promotes oxidative stress, which, in turn, leads to stress kinase activation, mitochondrial dysfunction, loss of nuclear structure and integrity and cell apoptosis. Original observations from our laboratory have proposed that Rac1 plays a key regulatory role in the generation of oxidative stress and downstream signaling events culminating in the onset of dysfunction of pancreatic β-cells under the duress of metabolic stress. However, precise molecular and cellular mechanisms underlying the metabolic roles of hyperactive Rac1 remain less understood. Using pharmacological and molecular biological approaches, we now report mistargetting of biologically-active Rac1 [GTP-bound conformation] to the nuclear compartment in clonal INS-1 cells, normal rat islets and human islets under HG conditions. Our findings also suggest that such a signaling step is independent of post-translational prenylation of Rac1. Evidence is also presented to highlight novel roles for sustained activation of Rac1 in HG-induced expression of Cluster of Differentiation 36 [CD36], a fatty acid transporter protein, which is implicated in cell apoptosis. Finally, our findings suggest that metformin, a biguanide anti-diabetic drug, at a clinically relevant concentration, prevents β-cell defects [Rac1 activation, nuclear association, CD36 expression, stress kinase and caspase-3 activation, and loss in metabolic viability] under the duress of glucotoxicity. Potential implications of these findings in the context of novel and direct regulation of islet β-cell function by metformin are discussed.
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Affiliation(s)
- Sartaj Baidwan
- β-Cell Biochemistry Laboratory, John D. Dingell VA Medical Center, Detroit, MI, USA.,Department of Pharmaceutical Sciences, Wayne State University, Detroit, MI, 48201, USA
| | - Anil Chekuri
- Shiley Eye Institute, University of California, La Jolla, CA, 92093, USA
| | - DiAnna L Hynds
- Department of Biology, Texas Woman's University, Denton, TX, 76204, USA
| | - Anjaneyulu Kowluru
- β-Cell Biochemistry Laboratory, John D. Dingell VA Medical Center, Detroit, MI, USA. .,Department of Pharmaceutical Sciences, Wayne State University, Detroit, MI, 48201, USA. .,B-4237 Research Service, John D. Dingell VA Medical Center, 4646 John R Street, Detroit, MI, 48201, USA.
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21
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Kowluru A, Kowluru RA. RACking up ceramide-induced islet β-cell dysfunction. Biochem Pharmacol 2018; 154:161-169. [PMID: 29715450 DOI: 10.1016/j.bcp.2018.04.026] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Accepted: 04/27/2018] [Indexed: 12/20/2022]
Abstract
The International Diabetes Federation predicts that by 2045 the number of individuals afflicted with diabetes will increase to 629 million. Furthermore, ∼352 million individuals with impaired glucose tolerance are at increased risk for developing diabetes. Several mechanisms have been proposed for the onset of metabolic dysfunction and demise of the islet β-cell leading to the pathogenesis of diabetes. It is widely accepted that the onset of type 2 diabetes is due to an intricate interplay between genetic expression of the disease and a multitude of factors including increased oxidative and endoplasmic reticulum stress consequential to glucolipotoxicity and inflammation. Compelling experimental evidence from in vitro and in vivo studies implicates intracellular generation of ceramide (CER), a biologically-active sphingolipid, as a trigger in the onset of β-cell demise under above pathological conditions. Recent pharmacological and molecular biological evidence affirms regulatory roles for Ras-related C3 botulinum toxin substrate 1 (Rac1), a small G protein, in the islet β-cell function in health and diabetes. In this Commentary, we overviewed the emerging evidence implicating potential cross-talk between Rac1 and ceramide signaling pathways in the onset of metabolic dysregulation of the islet β-cell culminating in impaired physiological insulin secretion, loss of β-cell mass and the onset of diabetes. Further, we propose a model depicting contributory roles of defective protein lipidation (prenylation) pathway in the induction of metabolic defects in the β-cell under metabolic stress conditions. Potential avenues for the identification of novel therapeutic targets for the prevention/treatment of diabetes and its associated complications are highlighted.
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Affiliation(s)
- Anjaneyulu Kowluru
- Biomedical Research Service, John D. Dingell VA Medical Center, Wayne State University, Detroit, MI 48201, USA; Department of Pharmaceutical Sciences, Wayne State University, Detroit, MI 48201, USA.
| | - Renu A Kowluru
- Department of Ophthalmology and Anatomy and Cell Biology, Wayne State University, Detroit, MI 48201, USA
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22
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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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Kowluru A. Role of G-proteins in islet function in health and diabetes. Diabetes Obes Metab 2017; 19 Suppl 1:63-75. [PMID: 28880478 PMCID: PMC5657296 DOI: 10.1111/dom.13011] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 05/03/2017] [Accepted: 05/12/2017] [Indexed: 12/17/2022]
Abstract
Glucose-stimulated insulin secretion (GSIS) involves interplay between metabolic and cationic events. Seminal contributions from multiple laboratories affirm essential roles for small G-proteins (Rac1, Cdc42, Arf6, Rab27A) in GSIS. Activation of these signalling proteins promotes cytoskeletal remodeling, transport and docking of insulin granules on the plasma membrane for exocytotic secretion of insulin. Evidence in rodent and human islets suggests key roles for lipidation (farnesylation and geranylgeranylation) of these G-proteins for their targeting to appropriate cellular compartments for optimal regulation of effectors leading to GSIS. Interestingly, however, inhibition of prenylation appears to cause mislocalization of non-prenylated, but (paradoxically) activated G-proteins, in "inappropriate" compartments leading to activation of stress kinases and onset of mitochondrial defects, loss in GSIS and apoptosis of the islet β-cell. This review highlights our current understanding of roles of G-proteins and their post-translational lipidation (prenylation) signalling networks in islet function in normal health, metabolic stress (glucolipotoxicity and ER stress) and diabetes. Critical knowledge gaps that need to be addressed for the development of therapeutics to halt defects in these signalling steps in β-cells in models of impaired insulin secretion and diabetes are also highlighted and discussed.
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Affiliation(s)
- Anjaneyulu Kowluru
- β-Cell Biochemistry Laboratory, John D. Dingell VA Medical Center, and Department of Pharmaceutical Sciences, Wayne State University, Detroit, Michigan
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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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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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Chondrocyte Apoptosis in the Pathogenesis of Osteoarthritis. Int J Mol Sci 2015; 16:26035-54. [PMID: 26528972 PMCID: PMC4661802 DOI: 10.3390/ijms161125943] [Citation(s) in RCA: 581] [Impact Index Per Article: 64.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2015] [Revised: 10/03/2015] [Accepted: 10/21/2015] [Indexed: 11/16/2022] Open
Abstract
Apoptosis is a highly-regulated, active process of cell death involved in development, homeostasis and aging. Dysregulation of apoptosis leads to pathological states, such as cancer, developmental anomalies and degenerative diseases. Osteoarthritis (OA), the most common chronic joint disease in the elderly population, is characterized by progressive destruction of articular cartilage, resulting in significant disability. Because articular cartilage depends solely on its resident cells, the chondrocytes, for the maintenance of extracellular matrix, the compromising of chondrocyte function and survival would lead to the failure of the articular cartilage. The role of subchondral bone in the maintenance of proper cartilage matrix has been suggested as well, and it has been proposed that both articular cartilage and subchondral bone interact with each other in the maintenance of articular integrity and physiology. Some investigators include both articular cartilage and subchondral bone as targets for repairing joint degeneration. In late-stage OA, the cartilage becomes hypocellular, often accompanied by lacunar emptying, which has been considered as evidence that chondrocyte death is a central feature in OA progression. Apoptosis clearly occurs in osteoarthritic cartilage; however, the relative contribution of chondrocyte apoptosis in the pathogenesis of OA is difficult to evaluate, and contradictory reports exist on the rate of apoptotic chondrocytes in osteoarthritic cartilage. It is not clear whether chondrocyte apoptosis is the inducer of cartilage degeneration or a byproduct of cartilage destruction. Chondrocyte death and matrix loss may form a vicious cycle, with the progression of one aggravating the other, and the literature reveals that there is a definite correlation between the degree of cartilage damage and chondrocyte apoptosis. Because current treatments for OA act only on symptoms and do not prevent or cure OA, chondrocyte apoptosis would be a valid target to modulate cartilage degeneration.
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Lee SJ, Kang HK, Song DK, Eum WS, Park J, Choi SY, Kwon HY. Transduction of PEP-1-heme oxygenase-1 into insulin-producing INS-1 cells protects them against cytokine-induced cell death. Biochem Biophys Res Commun 2015; 461:549-54. [DOI: 10.1016/j.bbrc.2015.04.076] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 04/07/2015] [Indexed: 11/27/2022]
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Veluthakal R, Kumar B, Mohammad G, Kowluru A, Kowluru RA. Tiam1-Rac1 Axis Promotes Activation of p38 MAP Kinase in the Development of Diabetic Retinopathy: Evidence for a Requisite Role for Protein Palmitoylation. Cell Physiol Biochem 2015; 36:208-20. [PMID: 25967961 PMCID: PMC4435616 DOI: 10.1159/000374065] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/02/2015] [Indexed: 01/14/2023] Open
Abstract
Background/Aims Evidence in multiple tissues, including retina, suggests generation of reactive oxygen species (ROS) and the ensuing oxidative stress as triggers for mitochondrial defects and cell apoptosis. We recently reported novel roles for Tiam1-Rac1-Nox2 axis in retinal mitochondrial dysfunction and cell death leading to the development of diabetic retinopathy. Herein, we tested the hypothesis that activation of p38 MAP kinase, a stress kinase, represents the downstream signaling event to Rac1-Nox2 activation in diabetes-induced metabolic stress leading to capillary cell apoptosis. Methods Activation of p38 MAP kinase was quantified by Western blotting in retinal endothelial cells incubated with high glucose (20 mM) for up to 96 hours, a duration where mitochondrial dysfunction and capillary cell apoptosis can be observed. NSC23766 and 2-bromopalmitate (2-BP) were used to assess the roles of Tiam1-Rac1 and palmitoylation pathways, respectively. Results Activation of p38 MAP kinase was observed as early as 3 hours after high glucose exposure, and continued until 96 hours. Consistent with this, p38 MAP kinase activation was significantly higher in the retina from diabetic mice compared to age-matched normal mice. NSC23766 markedly attenuated hyperglycemia-induced activation of p38 MAP kinase. Lastly, 2-BP inhibited glucose-induced Rac1, Nox2 and p38 MAP kinase activation in endothelial cells. Conclusions Tiam1-Rac1-mediated activation of Nox2 and p38 MAP kinase constitutes early signaling events leading to mitochondrial dysfunction and the development of diabetic retinopathy. Our findings also provide the first evidence to implicate novel roles for protein palmitoylation in this signaling cascade.
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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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Kowluru RA, Kowluru A, Veluthakal R, Mohammad G, Syed I, Santos JM, Mishra M. TIAM1-RAC1 signalling axis-mediated activation of NADPH oxidase-2 initiates mitochondrial damage in the development of diabetic retinopathy. Diabetologia 2014; 57:1047-56. [PMID: 24554007 DOI: 10.1007/s00125-014-3194-z] [Citation(s) in RCA: 106] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Accepted: 01/28/2014] [Indexed: 12/21/2022]
Abstract
AIMS/HYPOTHESIS In diabetes, increased retinal oxidative stress is seen before the mitochondria are damaged. Phagocyte-like NADPH oxidase-2 (NOX2) is the predominant cytosolic source of reactive oxygen species (ROS). Activation of Ras-related C3 botulinum toxin substrate 1 (RAC1), a NOX2 holoenzyme member, is necessary for NOX2 activation and ROS generation. In this study we assessed the role of T cell lymphoma invasion and metastasis (TIAM1), a guanine nucleotide exchange factor for RAC1, in RAC1 and NOX2 activation and the onset of mitochondrial dysfunction in in vitro and in vivo models of glucotoxicity and diabetes. METHODS RAC1 and NOX2 activation, ROS generation, mitochondrial damage and cell apoptosis were quantified in bovine retinal endothelial cells exposed to high glucose concentrations, in the retina from normal and streptozotocin-induced diabetic rats and mice, and the retina from human donors with diabetic retinopathy. RESULTS High glucose activated RAC1 and NOX2 (expression and activity) and increased ROS in endothelial cells before increasing mitochondrial ROS and mitochondrial DNA (mtDNA) damage. N6-[2-[[4-(diethylamino)-1-methylbutyl]amino]-6-methyl-4-pyrimidinyl]-2-methyl-4,6-quinolinediamine, trihydrochloride (NSC23766), a known inhibitor of TIAM1-RAC1, markedly attenuated RAC1 activation, total and mitochondrial ROS, mtDNA damage and cell apoptosis. An increase in NOX2 expression and membrane association of RAC1 and p47(phox) were also seen in diabetic rat retina. Administration of NSC23766 to diabetic mice attenuated retinal RAC1 activation and ROS generation. RAC1 activation and p47(phox) expression were also increased in the retinal microvasculature from human donors with diabetic retinopathy. CONCLUSIONS/INTERPRETATION The TIAM1-RAC1-NOX2 signalling axis is activated in the initial stages of diabetes to increase intracellular ROS leading to mitochondrial damage and accelerated capillary cell apoptosis. Strategies targeting TIAM1-RAC1 signalling could have the potential to halt the progression of diabetic retinopathy in the early stages of the disease.
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Affiliation(s)
- Renu A Kowluru
- Department of Ophthalmology, Wayne State University, Detroit, MI, USA
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Phagocyte-like NADPH oxidase [Nox2] in cellular dysfunction in models of glucolipotoxicity and diabetes. Biochem Pharmacol 2014; 88:275-83. [DOI: 10.1016/j.bcp.2014.01.017] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Revised: 01/10/2014] [Accepted: 01/13/2014] [Indexed: 02/01/2023]
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Arora DK, Machhadieh B, Matti A, Wadzinski BE, Ramanadham S, Kowluru A. High glucose exposure promotes activation of protein phosphatase 2A in rodent islets and INS-1 832/13 β-cells by increasing the posttranslational carboxylmethylation of its catalytic subunit. Endocrinology 2014; 155:380-91. [PMID: 24265448 PMCID: PMC3891936 DOI: 10.1210/en.2013-1773] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Existing evidence implicates regulatory roles for protein phosphatase 2A (PP2A) in a variety of cellular functions, including cytoskeletal remodeling, hormone secretion, and apoptosis. We report here activation of PP2A in normal rat islets and insulin-secreting INS-1 832/13 cells under the duress of hyperglycemic (HG) conditions. Small interfering RNA-mediated knockdown of the catalytic subunit of PP2A (PP2Ac) markedly attenuated glucose-induced activation of PP2A. HG, but not nonmetabolizable 3-O-methyl glucose or mannitol (osmotic control), significantly stimulated the methylation of PP2Ac at its C-terminal Leu-309, suggesting a novel role for this posttranslational modification in glucose-induced activation of PP2A. Moreover, knockdown of the cytosolic leucine carboxymethyl transferase 1 (LCMT1), which carboxymethylates PP2Ac, significantly attenuated PP2A activation under HG conditions. In addition, HG conditions, but not 3-O-methyl glucose or mannitol, markedly increased the expression of LCMT1. Furthermore, HG conditions significantly increased the expression of B55α, a regulatory subunit of PP2A, which has been implicated in islet dysfunction under conditions of oxidative stress and diabetes. Thapsigargin, a known inducer of endoplasmic reticulum stress, failed to exert any discernible effects on the carboxymethylation of PP2Ac, expression of LCMT1 and B55α, or PP2A activity, suggesting no clear role for endoplasmic reticulum stress in HG-induced activation of PP2A. Based on these findings, we conclude that exposure of the islet β-cell to HG leads to accelerated PP2A signaling pathway, leading to loss in glucose-induced insulin secretion.
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Affiliation(s)
- Daleep K Arora
- Beta-Cell Biochemistry Laboratory (D.K.A., A.K.), John D. Dingell Veterans Affairs Medical Center, and Department of Pharmaceutical Sciences (D.K.A., A.K.), Eugene Applebaum College of Pharmacy and Health Sciences, Wayne State University, Detroit, Michigan 48201; Section of Endocrinology, Diabetes and Metabolism (B.M.), University of Illinois at Chicago, Chicago, Illinois 60612; Department of Engineering and Science (A.M.), University of Detroit Mercy, Detroit, Michigan 48221; Department of Pharmacology (B.E.W.), Vanderbilt University Medical Center, Nashville, Tennessee 37232; and Department of Cell, Developmental, and Integrative Biology (S.R.), University of Alabama at Birmingham, Birmingham, Alabama 35294
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Elnakish MT, Hassanain HH, Janssen PM, Angelos MG, Khan M. Emerging role of oxidative stress in metabolic syndrome and cardiovascular diseases: important role of Rac/NADPH oxidase. J Pathol 2013; 231:290-300. [DOI: 10.1002/path.4255] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 08/26/2013] [Accepted: 09/01/2013] [Indexed: 01/04/2023]
Affiliation(s)
- Mohammad T Elnakish
- Dorothy M Davis Heart and Lung Research Institute; Ohio State University Wexner Medical Center; Columbus OH USA
- Department of Physiology and Cell Biology; Ohio State University Wexner Medical Center; Columbus OH USA
| | - Hamdy H Hassanain
- Department of Anesthesiology; The Ohio State University Wexner Medical Center; Columbus OH USA
| | - Paul M Janssen
- Dorothy M Davis Heart and Lung Research Institute; Ohio State University Wexner Medical Center; Columbus OH USA
- Department of Physiology and Cell Biology; Ohio State University Wexner Medical Center; Columbus OH USA
| | - Mark G Angelos
- Dorothy M Davis Heart and Lung Research Institute; Ohio State University Wexner Medical Center; Columbus OH USA
- Department of Emergency Medicine; Ohio State University Wexner Medical Center; Columbus OH USA
| | - Mahmood Khan
- Dorothy M Davis Heart and Lung Research Institute; Ohio State University Wexner Medical Center; Columbus OH USA
- Department of Emergency Medicine; Ohio State University Wexner Medical Center; Columbus OH USA
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Wilcock DM, Griffin WST. Down's syndrome, neuroinflammation, and Alzheimer neuropathogenesis. J Neuroinflammation 2013; 10:84. [PMID: 23866266 PMCID: PMC3750399 DOI: 10.1186/1742-2094-10-84] [Citation(s) in RCA: 137] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Accepted: 05/28/2013] [Indexed: 12/26/2022] Open
Abstract
Down syndrome (DS) is the result of triplication of chromosome 21 (trisomy 21) and is the prevailing cause of mental retardation. In addition to the mental deficiencies and physical anomalies noted at birth, triplication of chromosome 21 gene products results in the neuropathological and cognitive changes of Alzheimer's disease (AD). Mapping of the gene that encodes the precursor protein (APP) of the β-amyloid (Aβ) present in the Aβ plaques in both AD and DS to chromosome 21 was strong evidence that this chromosome 21 gene product was a principal neuropathogenic culprit in AD as well as DS. The discovery of neuroinflammatory changes, including dramatic proliferation of activated glia overexpressing a chromosome 2 gene product--the pluripotent immune cytokine interleukin-1 (IL-1)--and a chromosome 21 gene product--S100B--in the brains of fetuses, neonates, and children with DS opened the possibility that early events in Alzheimer pathogenesis were driven by cytokines. The specific chromosome 21 gene products and the complexity of the mechanisms they engender that give rise to the neuroinflammatory responses noted in fetal development of the DS brain and their potential as accelerators of Alzheimer neuropathogenesis in DS are topics of this review, particularly as they relate to development and propagation of neuroinflammation, the consequences of which are recognized clinically and neuropathologically as Alzheimer's disease.
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Affiliation(s)
- Donna M Wilcock
- Department of Physiology, Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY 40536, USA
| | - W Sue T Griffin
- Donald W. Reynolds Department of Geriatrics, Donald W. Reynolds Institute on Aging, University of Arkansas for Medical Sciences, 629 Jack Stephens Dr., Little Rock, AR 72205, USA
- The Geriatric Research Education Clinical Center, Central Arkansas HealthCare System, Little Rock, AR, USA
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Huh KH, Cho Y, Kim BS, Do JH, Park YJ, Joo DJ, Kim MS, Kim YS. The role of thioredoxin 1 in the mycophenolic acid-induced apoptosis of insulin-producing cells. Cell Death Dis 2013; 4:e721. [PMID: 23846223 PMCID: PMC3730420 DOI: 10.1038/cddis.2013.247] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 06/07/2013] [Accepted: 06/07/2013] [Indexed: 01/12/2023]
Abstract
Mycophenolic acid (MPA) is one of many effective immunosuppressive drugs. However, MPA can induce cellular toxicity and impair cellular function in β-cells. To explore the effects of MPA and the relation between MPA and Trx-1, we used various methods, including an Illumina microarray, to identify the genes regulated during pancreatic β-cell death following MPA treatment. INS-1E cells (a pancreatic β-cell line) and isolated rat islets were treated with MPA for 12, 24, or 36 h, and subsequent microarray analysis showed that (Trx1) gene expression was significantly reduced by MPA. Further, Trx1 overexpression increased the cell viability, decreased the activations of c-jun N-terminal kinase (JNK) and caspase-3 by MPA, and attenuated ROS upregulation by MPA. Furthermore, siRNA knockdown of Trx1 increased MPA-induced cell death and the activations of p-JNK and caspase-3, and MPA significantly provoked the apoptosis of insulin-secreting cells via Trx1 downregulation. Our findings suggest that the prevention of Trx1 downregulation in response to MPA is critical for successful islet transplantation.
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Affiliation(s)
- K H Huh
- Research Institute for Transplantation, Yonsei University College of Medicine, Seoul, Republic of Korea
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Santoro N, Weiss R. Metabolic syndrome in youth: current insights and novel serum biomarkers. Biomark Med 2013; 6:719-27. [PMID: 23227837 DOI: 10.2217/bmm.12.85] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Paralleling the worldwide epidemic in childhood obesity, in the last decade we have observed a rise in the prevalence of metabolic syndrome (MetS) in pediatrics. The MetS comprises a cluster of cardiovascular risk factors. Multiple definitions have been proposed for the syndrome in the pediatric age group, but they are very difficult to test and validate. Thus, in this paper we will discuss the current knowledge in pediatric MetS and the potential role of novel biomarkers in the pathogenesis and diagnosis of MetS.
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Affiliation(s)
- Nicola Santoro
- Department of Pediatrics, Yale University School of Medicine, 330 Cedar Street, PO Box 208064, New Haven, CT 06520, USA.
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Koulajian K, Desai T, Liu GC, Ivovic A, Patterson JN, Tang C, El-Benna J, Joseph JW, Scholey JW, Giacca A. NADPH oxidase inhibition prevents beta cell dysfunction induced by prolonged elevation of oleate in rodents. Diabetologia 2013; 56:1078-87. [PMID: 23429921 PMCID: PMC3622749 DOI: 10.1007/s00125-013-2858-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Accepted: 01/21/2013] [Indexed: 12/16/2022]
Abstract
AIMS/HYPOTHESIS The activation of NADPH oxidase has been implicated in NEFA-induced beta cell dysfunction. However, the causal role of this activation in vivo remains unclear. Here, using rodents, we investigated whether pharmacological or genetic inhibition of NADPH oxidase could prevent NEFA-induced beta cell dysfunction in vivo. METHODS Normal rats were infused for 48 h with saline or oleate with or without the NADPH oxidase inhibitor apocynin. In addition, NADPH oxidase subunit p47(phox)-null mice and wild-type littermate controls were infused with saline or oleate for 48 h. This was followed by measurement of NADPH oxidase activity, reactive oxygen species (ROS) and superoxide imaging and assessment of beta cell function in isolated islets and hyperglycaemic clamps. RESULTS Oleate infusion in rats increased NADPH oxidase activity, consistent with increased total but not mitochondrial superoxide in islets and impaired beta cell function in isolated islets and during hyperglycaemic clamps. Co-infusion of apocynin with oleate normalised NADPH oxidase activity and total superoxide levels and prevented beta cell dysfunction. Similarly, 48 h NEFA elevation in wild-type mice increased total but not mitochondrial superoxide and impaired beta cell function in isolated islets. p47(phox)-null mice were protected against these effects when subjected to 48 h oleate infusion. Finally, oleate increased the levels of total ROS, in both models, whereas inhibition of NADPH oxidase prevented this increase, suggesting that NADPH oxidase is the main source of ROS in this model. CONCLUSIONS/INTERPRETATION These data show that NADPH-oxidase-derived cytosolic superoxide is increased in islets upon oleate infusion in vivo; and whole-body NADPH-oxidase inhibition decreases superoxide in concert with restoration of islet function.
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Affiliation(s)
- K. Koulajian
- Department of Physiology, University of Toronto, Medical Sciences Building, Room 3336-1 King’s College Circle, Toronto, ON Canada M5S 1A8
| | - T. Desai
- Department of Physiology, University of Toronto, Medical Sciences Building, Room 3336-1 King’s College Circle, Toronto, ON Canada M5S 1A8
| | - G. C. Liu
- Institute of Medical Sciences, University of Toronto, Toronto, ON Canada
| | - A. Ivovic
- Department of Physiology, University of Toronto, Medical Sciences Building, Room 3336-1 King’s College Circle, Toronto, ON Canada M5S 1A8
| | - J. N. Patterson
- School of Pharmacy, University of Waterloo, Waterloo, ON Canada
| | - C. Tang
- Department of Physiology, University of Toronto, Medical Sciences Building, Room 3336-1 King’s College Circle, Toronto, ON Canada M5S 1A8
| | - J. El-Benna
- Inserm, U773, Centre de Recherche Biomédicale Bichat Beaujon CRB3, Paris, France
- Université Paris 7 site Bichat, UMRS 773, Paris, France
| | - J. W. Joseph
- School of Pharmacy, University of Waterloo, Waterloo, ON Canada
| | - J. W. Scholey
- Institute of Medical Sciences, University of Toronto, Toronto, ON Canada
- Division of Nephrology, University of Toronto, Toronto, ON Canada
| | - A. Giacca
- Department of Physiology, University of Toronto, Medical Sciences Building, Room 3336-1 King’s College Circle, Toronto, ON Canada M5S 1A8
- Institute of Medical Sciences, University of Toronto, Toronto, ON Canada
- Department of Medicine, University of Toronto, Toronto, ON Canada
- Banting and Best Diabetes Centre, University of Toronto, Toronto, ON Canada
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Mohammed AM, Kowluru A. Activation of apocynin-sensitive NADPH oxidase (Nox2) activity in INS-1 832/13 cells under glucotoxic conditions. Islets 2013; 5:129-31. [PMID: 23695780 DOI: 10.4161/isl.25058] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Several lines of recent evidence provided compelling evidence to suggest increased generation of reactive oxygen species (ROS) as causal for mitochondrial dysregulation and apoptosis in islet β-cells exposed to noxious stimuli including high glucose, lipids and proinflammatory cytokines. Studies along these lines are also suggestive of a significant contributory role for NADPH oxidase in the generation of ROS under the above conditions. We have recently reported a marked increase in the expression and activation of cytosolic components of NADPH oxidase (p47phox, Rac1) in cell culture models of glucotoxicity and in islets from T2DM animals (Zucker Diabetic Fatty rat) and humans. In this communication, we provide further evidence indicating significant activation of NADPH activity (~2-fold) in INS-1 832/13 cells exposed to chronic hyperglycemic conditions (20 mM; 48 h). We also report marked attenuation of this activity, by apocynin, a selective inhibitor of phagocyte-like NADPH oxidase (Nox2) activity. Together, our findings implicate Nox2 as a source for ROS generation in β-cells exposed to glucotoxic conditions.
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Affiliation(s)
- Abiy M Mohammed
- 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 USA
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Taylor-Fishwick DA. NOX, NOX Who is There? The Contribution of NADPH Oxidase One to Beta Cell Dysfunction. Front Endocrinol (Lausanne) 2013; 4:40. [PMID: 23565109 PMCID: PMC3615241 DOI: 10.3389/fendo.2013.00040] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Accepted: 03/13/2013] [Indexed: 01/15/2023] Open
Abstract
Predictions of diabetes prevalence over the next decades warrant the aggressive discovery of new approaches to stop or reverse loss of functional beta cell mass. Beta cells are recognized to have a relatively high sensitivity to reactive oxygen species (ROS) and become dysfunctional under oxidative stress conditions. New discoveries have identified NADPH oxidases in beta cells as contributors to elevated cellular ROS. Reviewed are recent reports that evidence a role for NADPH oxidase-1 (NOX-1) in beta cell dysfunction. NOX-1 is stimulated by inflammatory cytokines that are elevated in diabetes. First, regulation of cytokine-stimulated NOX-1 expression has been linked to inflammatory lipid mediators derived from 12-lipoxygenase activity. For the first time in beta cells these data integrate distinct pathways associated with beta cell dysfunction. Second, regulation of NOX-1 in beta cells involves feed-forward control linked to elevated ROS and Src-kinase activation. This potentially results in unbridled ROS generation and identifies candidate targets for pharmacologic intervention. Third, consideration is provided of new, first-in-class, selective inhibitors of NOX-1. These compounds could have an important role in assessing a disruption of NOX-1/ROS signaling as a new approach to preserve and protect beta cell mass in diabetes.
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Affiliation(s)
- David A. Taylor-Fishwick
- Department of Internal Medicine, Strelitz Diabetes Center, Eastern Virginia Medical SchoolNorfolk, VA, USA
- Department of Microbiology and Molecular Cell Biology, Eastern Virginia Medical SchoolNorfolk, VA, USA
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Abstract
Metabolic syndrome comprises a cluster of cardiovascular risk factors (hypertension, altered glucose metabolism, dyslipidemia, and abdominal obesity) that occur in obese children. However, metabolic syndrome can also occur in lean individuals, suggesting that obesity is a marker for the syndrome, not a cause. Metabolic syndrome is difficult to define, due to its nonuniform classification and reliance on hard cutoffs in the evaluation of disorders with non-Gaussian distributions. Defining the syndrome is even more difficult in children, owing to racial and pubertal differences and lack of cardiovascular events. Lipid partitioning among specific fat depots is associated with insulin resistance, which can lead to mitochondrial overload and dysfunctional subcellular energy use and drive the various elements of metabolic syndrome. Multiple environmental factors, in particular a typical Western diet, drive mitochondrial overload, while other changes in Western society, such as stress and sleep deprivation, increase insulin resistance and the propensity for food intake. These culminate in an adverse biochemical phenotype, including development of altered glucose metabolism and early atherogenesis during childhood and early adulthood.
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Affiliation(s)
- Ram Weiss
- Department of Pediatrics, Hadassah Hebrew University School of Medicine, Jerusalem, Israel
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Upregulation of phagocyte-like NADPH oxidase by cytokines in pancreatic beta-cells: attenuation of oxidative and nitrosative stress by 2-bromopalmitate. Biochem Pharmacol 2012; 85:109-14. [PMID: 23092759 DOI: 10.1016/j.bcp.2012.09.024] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Accepted: 09/25/2012] [Indexed: 12/17/2022]
Abstract
Phagocyte-like NADPH oxidase (Nox2) has been shown to play regulatory roles in the metabolic dysfunction of the islet β-cell under the duress of glucolipotoxic conditions and exposure to proinflammatory cytokines. However, the precise mechanisms underlying Nox2 activation by these stimuli remain less understood. To this end, we report a time-dependent phosphorylation of p47phox, a cytosolic subunit of Nox2, by cytomix (IL-1β+TNFα+IFNγ) in insulin-secreting INS-1 832/13 cells. Furthermore, cytomix induced the expression of gp91phox, a membrane component of Nox2. 2-Bromopalmitate (2-BP), a known inhibitor of protein palmitoylation, markedly attenuated cytokine-induced, Nox2-mediated reactive oxygen species (ROS) generation and inducible nitric oxide synthase (iNOS)-mediated nitric oxide (NO) generation. However, 2-BP failed to exert any significant effects on cytomix-induced CHOP expression, a marker for endoplasmic reticulum stress. Together, our findings identify palmitoyltransferase as a target for inhibition of cytomix-induced oxidative (ROS generation) and nitrosative (NO generation) stress in the pancreatic β-cell.
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Novotny GW, Lundh M, Backe MB, Christensen DP, Hansen JB, Dahllöf MS, Pallesen EMH, Mandrup-Poulsen T. Transcriptional and translational regulation of cytokine signaling in inflammatory β-cell dysfunction and apoptosis. Arch Biochem Biophys 2012; 528:171-84. [PMID: 23063755 DOI: 10.1016/j.abb.2012.09.014] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 09/20/2012] [Accepted: 09/22/2012] [Indexed: 12/19/2022]
Abstract
Disease is conventionally viewed as the chaotic inappropriate outcome of deranged tissue function resulting from aberrancies in cellular processes. Yet the patho-biology of cellular dysfunction and death encompasses a coordinated network no less sophisticated and regulated than maintenance of homeostatic balance. Cellular demise is far from passive subordination to stress but requires controlled coordination of energy-requiring activities including gene transcription and protein translation that determine the graded transition between defensive mechanisms, cell cycle regulation, dedifferentiation and ultimately to the activation of death programmes. In fact, most stressors stimulate both homeostasis and regeneration on one hand and impairment and destruction on the other, depending on the ambient circumstances. Here we illustrate this bimodal ambiguity in cell response by reviewing recent progress in our understanding of how the pancreatic β cell copes with inflammatory stress by changing gene transcription and protein translation by the differential and interconnected action of reactive oxygen and nitric oxide species, microRNAs and posttranslational protein modifications.
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Affiliation(s)
- Guy W Novotny
- Section of Endocrinological Research, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
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Syed I, Szulc ZM, Ogretmen B, Kowluru A. L- threo -C6-pyridinium-ceramide bromide, a novel cationic ceramide, induces NADPH oxidase activation, mitochondrial dysfunction and loss in cell viability in INS 832/13 β-cells. Cell Physiol Biochem 2012; 30:1051-8. [PMID: 23052231 DOI: 10.1159/000341481] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/17/2012] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Emerging evidence indicates that exposure of isolated pancreatic β-cells to elevated glucose [glucotoxicity] or saturated fatty acids such as palmitate [lipotoxicity] or both [glucolipotoxicity] results in excessive intracellular oxidative stress mediated by phagocyte-like NADPH oxidase [Nox2]. Pharmacological evidence also implicates the intracellular generation of ceramide [CER] as one of the mediators of palmitate-induced cytotoxicity of the islet β- cell. Herein, we investigated the effects of L-threo-C6-pyridinium-ceramide bromide, a novel water soluble cationic ceramide [Ws-CER], on mitochondrial function and cell viability in insulin-secreting INS 832/13 cells. METHODS Ws-CER, was synthesized as we reported earlier. Rac1 activation was quantitated by pull-down assay. Mitochondrial membrane potential was quantitated by JC-1 staining. Nox2 subunit expression and caspase-3 activity were determined by Western blotting. RESULTS Our findings suggested a marked increase in the Nox2 activation [i.e., ROS generation and subunit expression and activation] in cells exposed to Ws-CER. We also noticed a significant reduction in mitochondrial membrane potential, increased in caspase-3 activity and associated loss in cell viability in Ws-CER-treated cells. CONCLUSION Based on these data we conclude that ceramide-induced Nox2-mediated oxidative stress couples mitochondrial dysfunction to loss in cell viability in the pancreatic β-cell.
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Affiliation(s)
- Ismail Syed
- Beta-Cell Biochemistry Laboratory, John D. Dingell VA Medical Center and Pharmaceutical Sciences, Wayne State University, Detroit, MI 48201 , USA
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Hyperactivation of protein phosphatase 2A in models of glucolipotoxicity and diabetes: potential mechanisms and functional consequences. Biochem Pharmacol 2012; 84:591-7. [PMID: 22583922 DOI: 10.1016/j.bcp.2012.05.003] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Revised: 05/03/2012] [Accepted: 05/03/2012] [Indexed: 01/22/2023]
Abstract
The protein phosphatase 2A [PP2A] family of enzymes has been implicated in the regulation of a variety of cellular functions including hormone secretion, growth, survival and apoptosis. PP2A accounts for ~1% of total cellular protein and ∼ 80% of total serine/threonine phosphatases, thus representing a major class of protein phosphatases in mammalian cells. Despite significant advances in our current understanding of regulation of cellular function by PP2A under physiological conditions, little is understood with regard to its regulation under various pathological conditions, such as diabetes. Emerging evidence suggests hyperactivation of PP2A in liver, muscle, retina and the pancreatic islet under the duress of glucolipotoxicity and diabetes. Interestingly, pharmacological inhibition of PP2A or siRNA-mediated depletion of the catalytic subunit of PP2A [PP2Ac] levels largely restored PP2A activity to near normal levels under these conditions. Herein, we provide an overview of PP2A subunit expression and activity in in vitro and in vivo models of glucolipotoxicity and diabetes, and revisit the existing data, which are suggestive of alterations in post-translational methylation, phosphorylation and nitration of PP2Ac under these conditions. Potential significance of hyperactive PP2A in the context of cell function, survival and apoptosis is also highlighted. It is hoped that this commentary will provide a basis for future studies to explore the potential for PP2Ac as a therapeutic target for the treatment of diabetes and other metabolic disorders.
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Tersey SA, Nishiki Y, Templin AT, Cabrera SM, Stull ND, Colvin SC, Evans-Molina C, Rickus JL, Maier B, Mirmira RG. Islet β-cell endoplasmic reticulum stress precedes the onset of type 1 diabetes in the nonobese diabetic mouse model. Diabetes 2012; 61:818-27. [PMID: 22442300 PMCID: PMC3314371 DOI: 10.2337/db11-1293] [Citation(s) in RCA: 265] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Type 1 diabetes is preceded by islet β-cell dysfunction, but the mechanisms leading to β-cell dysfunction have not been rigorously studied. Because immune cell infiltration occurs prior to overt diabetes, we hypothesized that activation of inflammatory cascades and appearance of endoplasmic reticulum (ER) stress in β-cells contributes to insulin secretory defects. Prediabetic nonobese diabetic (NOD) mice and control diabetes-resistant NOD-SCID and CD1 strains were studied for metabolic control and islet function and gene regulation. Prediabetic NOD mice were relatively glucose intolerant and had defective insulin secretion with elevated proinsulin:insulin ratios compared with control strains. Isolated islets from NOD mice displayed age-dependent increases in parameters of ER stress, morphologic alterations in ER structure by electron microscopy, and activation of nuclear factor-κB (NF-κB) target genes. Upon exposure to a mixture of proinflammatory cytokines that mimics the microenvironment of type 1 diabetes, MIN6 β-cells displayed evidence for polyribosomal runoff, a finding consistent with the translational initiation blockade characteristic of ER stress. We conclude that β-cells of prediabetic NOD mice display dysfunction and overt ER stress that may be driven by NF-κB signaling, and strategies that attenuate pathways leading to ER stress may preserve β-cell function in type 1 diabetes.
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Affiliation(s)
- Sarah A Tersey
- Department of Pediatrics, Indiana University School of Medicine,Indianapolis, IN, USA.
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Abstract
Despite a lack of consistent diagnostic criteria, the metabolic syndrome (MetS) is increasingly evident in children and adolescents, portending a tsunami of chronic disease and mortality as this generation ages. The diagnostic criteria for MetS apply absolute cutoffs to continuous variables and fail to take into account aging, pubertal changes, and race/ethnicity. We attempt to define MetS mechanistically to determine its specific etiologies and to identify targets for therapy. Whereas the majority of studies document a relationship of visceral fat to insulin resistance, ectopic liver fat correlates better with dysfunctional insulin dynamics from which the rest of MetS derives. In contrast to the systemic metabolism of glucose, the liver is the primary metabolic clearinghouse for 4 specific foodstuffs that have been associated with the development of MetS: trans-fats, branched-chain amino acids, ethanol, and fructose. These 4 substrates (1) are not insulin regulated and (2) deliver metabolic intermediates to hepatic mitochondria without an appropriate "pop-off" mechanism for excess substrate, enhancing lipogenesis and ectopic adipose storage. Excessive fatty acid derivatives interfere with hepatic insulin signal transduction. Reactive oxygen species accumulate, which cannot be quenched by adjacent peroxisomes; these reactive oxygen species reach the endoplasmic reticulum, leading to a compensatory process termed the "unfolded protein response," driving further insulin resistance and eventually insulin deficiency. No obvious drug target exists in this pathway; thus, the only rational therapeutic approaches remain (1) altering hepatic substrate availability (dietary modification), (2) reducing hepatic substrate flux (high fiber), or (3) increasing mitochondrial efficiency (exercise).
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Affiliation(s)
- Andrew A. Bremer
- Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Michele Mietus-Snyder
- Department of Pediatrics and Children’s National Obesity Institute, Children’s National Medical Center, Washington, District of Columbia; and
| | - Robert H. Lustig
- Department of Pediatrics, University of California, San Francisco, San Francisco, California
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Neuroinflammation in the aging down syndrome brain; lessons from Alzheimer's disease. Curr Gerontol Geriatr Res 2012; 2012:170276. [PMID: 22454637 PMCID: PMC3290800 DOI: 10.1155/2012/170276] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Accepted: 11/15/2011] [Indexed: 12/25/2022] Open
Abstract
Down syndrome (DS) is the most genetic cause of mental retardation and is caused by the triplication of chromosome 21. In addition to the disabilities caused early in life, DS is also noted as causing Alzheimer's-disease-like pathological changes in the brain, leading to 50-70% of DS patients showing dementia by 60-70 years of age. Inflammation is a complex process that has a key role to play in the pathogenesis of Alzheimer's disease. There is relatively little understood about inflammation in the DS brain and how the genetics of DS may alter this inflammatory response and change the course of disease in the DS brain. The goal of this review is to highlight our current understanding of inflammation in Alzheimer's disease and predict how inflammation may affect the pathology of the DS brain based on this information and the known genetic changes that occur due to triplication of chromosome 21.
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Amanso AM, Griendling KK. Differential roles of NADPH oxidases in vascular physiology and pathophysiology. Front Biosci (Schol Ed) 2012; 4:1044-64. [PMID: 22202108 DOI: 10.2741/s317] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Reactive oxygen species (ROS) are produced by all vascular cells and regulate the major physiological functions of the vasculature. Production and removal of ROS are tightly controlled and occur in discrete subcellular locations, allowing for specific, compartmentalized signaling. Among the many sources of ROS in the vessel wall, NADPH oxidases are implicated in physiological functions such as control of vasomotor tone, regulation of extracellular matrix and phenotypic modulation of vascular smooth muscle cells. They are involved in the response to injury, whether as an oxygen sensor during hypoxia, as a regulator of protein processing, as an angiogenic stimulus, or as a mechanism of wound healing. These enzymes have also been linked to processes leading to disease development, including migration, proliferation, hypertrophy, apoptosis and autophagy. As a result, NADPH oxidases participate in atherogenesis, systemic and pulmonary hypertension and diabetic vascular disease. The role of ROS in each of these processes and diseases is complex, and a more full understanding of the sources, targets, cell-specific responses and counterbalancing mechanisms is critical for the rational development of future therapeutics.
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Affiliation(s)
- Angelica M Amanso
- Department of Medicine, Division of Cardiology, Emory University, Division of Cardiology, Atlanta, GA 30322, USA
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50
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Syed I, Kyathanahalli CN, Jayaram B, Govind S, Rhodes CJ, Kowluru RA, Kowluru A. Increased phagocyte-like NADPH oxidase and ROS generation in type 2 diabetic ZDF rat and human islets: role of Rac1-JNK1/2 signaling pathway in mitochondrial dysregulation in the diabetic islet. Diabetes 2011; 60:2843-52. [PMID: 21911753 PMCID: PMC3198065 DOI: 10.2337/db11-0809] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
OBJECTIVE To determine the subunit expression and functional activation of phagocyte-like NADPH oxidase (Nox), reactive oxygen species (ROS) generation and caspase-3 activation in the Zucker diabetic fatty (ZDF) rat and diabetic human islets. RESEARCH DESIGN AND METHODS Expression of core components of Nox was quantitated by Western blotting and densitometry. ROS levels were quantitated by the 2',7'-dichlorofluorescein diacetate method. Rac1 activation was quantitated using the gold-labeled immunosorbent assay kit. RESULTS Levels of phosphorylated p47(phox), active Rac1, Nox activity, ROS generation, Jun NH(2)-terminal kinase (JNK) 1/2 phosphorylation, and caspase-3 activity were significantly higher in the ZDF islets than the lean control rat islets. Chronic exposure of INS 832/13 cells to glucolipotoxic conditions resulted in increased JNK1/2 phosphorylation and caspase-3 activity; such effects were largely reversed by SP600125, a selective inhibitor of JNK. Incubation of normal human islets with high glucose also increased the activation of Rac1 and Nox. Lastly, in a manner akin to the ZDF diabetic rat islets, Rac1 expression, JNK1/2, and caspase-3 activation were also significantly increased in diabetic human islets. CONCLUSIONS We provide the first in vitro and in vivo evidence in support of an accelerated Rac1-Nox-ROS-JNK1/2 signaling pathway in the islet β-cell leading to the onset of mitochondrial dysregulation in diabetes.
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Affiliation(s)
- Ismail Syed
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Detroit, Michigan
| | | | - Bhavaani Jayaram
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Detroit, Michigan
| | - Sudha Govind
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Detroit, Michigan
| | - Christopher J. Rhodes
- Kovler Diabetes Center, Department of Medicine, Section of Endocrinology, Diabetes, and Metabolism, University of Chicago, Chicago, Illinois
| | - Renu A. Kowluru
- Kresge Eye Institute, Wayne State University, Detroit, Michigan
| | - Anjaneyulu Kowluru
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy and Health Sciences, Detroit, Michigan
- β-Cell Biochemistry Laboratory, John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan
- Corresponding author: Anjaneyulu Kowluru,
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