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Delangre E, Liu J, Tolu S, Maouche K, Armanet M, Cattan P, Pommier G, Bailbé D, Movassat J. Underlying mechanisms of glucocorticoid-induced β-cell death and dysfunction: a new role for glycogen synthase kinase 3. Cell Death Dis 2021; 12:1136. [PMID: 34876563 PMCID: PMC8651641 DOI: 10.1038/s41419-021-04419-8] [Citation(s) in RCA: 6] [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] [Received: 06/22/2021] [Revised: 11/10/2021] [Accepted: 11/18/2021] [Indexed: 11/08/2022]
Abstract
Glucocorticoids (GCs) are widely prescribed for their anti-inflammatory and immunosuppressive properties as a treatment for a variety of diseases. The use of GCs is associated with important side effects, including diabetogenic effects. However, the underlying mechanisms of GC-mediated diabetogenic effects in β-cells are not well understood. In this study we investigated the role of glycogen synthase kinase 3 (GSK3) in the mediation of β-cell death and dysfunction induced by GCs. Using genetic and pharmacological approaches we showed that GSK3 is involved in GC-induced β-cell death and impaired insulin secretion. Further, we unraveled the underlying mechanisms of GC-GSK3 crosstalk. We showed that GSK3 is marginally implicated in the nuclear localization of GC receptor (GR) upon ligand binding. Furthermore, we showed that GSK3 regulates the expression of GR at mRNA and protein levels. Finally, we dissected the proper contribution of each GSK3 isoform and showed that GSK3β isoform is sufficient to mediate the pro-apoptotic effects of GCs in β-cells. Collectively, in this work we identified GSK3 as a viable target to mitigate GC deleterious effects in pancreatic β-cells.
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Affiliation(s)
- Etienne Delangre
- Université de Paris, BFA, UMR 8251, CNRS, Team « Biologie et Pathologie du Pancréas Endocrine », Paris, France
| | - Junjun Liu
- Université de Paris, BFA, UMR 8251, CNRS, Team « Biologie et Pathologie du Pancréas Endocrine », Paris, France
- Shandong Institute of Endocrine & Metabolic Diseases, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Stefania Tolu
- Université de Paris, BFA, UMR 8251, CNRS, Team « Biologie et Pathologie du Pancréas Endocrine », Paris, France
| | - Kamel Maouche
- Université de Paris, BFA, UMR 8251, CNRS, Team « Biologie et Pathologie du Pancréas Endocrine », Paris, France
| | - Mathieu Armanet
- Cell Therapy Unit, Saint-Louis hospital, AP-HP, and Université de Paris, Paris, France
| | - Pierre Cattan
- Cell Therapy Unit, Saint-Louis hospital, AP-HP, and Université de Paris, Paris, France
| | - Gaëlle Pommier
- Université de Paris, BFA, UMR 8251, CNRS, Team « Biologie et Pathologie du Pancréas Endocrine », Paris, France
| | - Danielle Bailbé
- Université de Paris, BFA, UMR 8251, CNRS, Team « Biologie et Pathologie du Pancréas Endocrine », Paris, France
| | - Jamileh Movassat
- Université de Paris, BFA, UMR 8251, CNRS, Team « Biologie et Pathologie du Pancréas Endocrine », Paris, France.
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Yang C, Li J, Sun F, Zhou H, Yang J, Yang C. The functional duality of SGK1 in the regulation of hyperglycemia. Endocr Connect 2020; 9:R187-R194. [PMID: 32621586 PMCID: PMC7424354 DOI: 10.1530/ec-20-0225] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 07/02/2020] [Indexed: 12/11/2022]
Abstract
Hyperglycemia is the consequence of blood glucose dysregulation and a driving force of diabetic complications including retinopathy, nephropathy and cardiovascular diseases. The serum and glucocorticoid inducible kinase-1 (SGK1) has been suggested in the modulation of various pathophysiological activities. However, the role of SGK1 in blood glucose homeostasis remains less appreciated. In this review, we intend to summarize the function of SGK1 in glucose level regulation and to examine the evidence supporting the therapeutic potential of SGK1 inhibitors in hyperglycemia. Ample evidence points to the controversial roles of SGK1 in pancreatic insulin secretion and peripheral insulin sensitivity, which reflects the complex interplay between SGK1 activation and blood glucose fluctuation. Furthermore, SGK1 is engaged in glucose absorption and excretion in intestine and kidney and participates in the progression of hyperglycemia-induced secondary organ damage. As a net effect, blockage of SGK1 activation via either pharmacological inhibition or genetic manipulation seems to be helpful in glucose control at varying diabetic stages.
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Affiliation(s)
- Chunliang Yang
- Department of Integrated Traditional Chinese and Western Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- The Center for Biomedical Research, Tongji Hospital Research Building, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Junyi Li
- Department of Integrated Traditional Chinese and Western Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Fei Sun
- The Center for Biomedical Research, Tongji Hospital Research Building, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Haifeng Zhou
- Department of Integrated Traditional Chinese and Western Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jia Yang
- Department of Integrated Traditional Chinese and Western Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Correspondence should be addressed to C Yang or J Yang: or
| | - Chao Yang
- Department of Gerontology, Hubei Provincial Hospital of Integrated Chinese and Western Medicine, Wuhan, China
- Correspondence should be addressed to C Yang or J Yang: or
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Khadrawy YA, Sawie HG, Hosny EN. Neuroprotective effect of curcumin nanoparticles against rat model of status epilepticus induced by pilocarpine. JOURNAL OF COMPLEMENTARY & INTEGRATIVE MEDICINE 2018; 15:jcim-2017-0117. [PMID: 29570450 DOI: 10.1515/jcim-2017-0117] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 02/20/2018] [Indexed: 11/15/2022]
Abstract
Abstract
Background
The present study aims to investigate the neuroprotective effect of curcumin nanoparticles (Cur-NP) on the rat model of status epilepticus (SE) induced by pilocarpine.
Methods
In the present study, animals were divided into three groups: control animals, rat model of SE induced by a single dose of pilocarpine (380 mg/kg) injected intraperitoneally, and rat model of SE that received a daily intraperitoneal injection of Cur-NP (50 mg/kg) for four consecutive days prior to pilocarpine administration.
Results
The present results revealed a state of oxidative stress in the cortex and hippocampus of rat model of SE as compared to control. This was evident from the significant increase in lipid peroxidation and the significant decrease in reduced glutathione and nitric oxide. In addition, a significant increase in the levels of tumor necrosis factor-alpha (TNF-α) and caspase-3 was detected in the two studied brain regions of rat model of SE. The activities of acetylcholinesterase (AchE) and Na+/K+-ATPase decreased significantly in the cortex and hippocampus of rat model of SE. Protection with Cur-NP prevented oxidative stress and improved the elevated level of caspase-3 in the hippocampus and cortex and the hippocampal TNF-α to nonsignificant changes. Although Cur-NP prevented the decrease in AchE activity in the two studied brain regions, it failed to return Na+/K+-ATPase activity to its normal value.
Conclusions
It is clear from the present findings that Cur-NP could prevent the oxidative stress and neuroinflammation and cell death that were induced during SE. This in turn may help in ameliorating the subsequent cascades of events that follow SE and its development into epileptogenesis.
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Affiliation(s)
- Yasser A Khadrawy
- Medical Physiology Department, Medical Division, National Research Center, El-Behouth St., Giza, Egypt
| | - Hussein G Sawie
- Medical Physiology Department, Medical Division, National Research Center, El-Behouth St., Giza, Egypt
| | - Eman N Hosny
- Medical Physiology Department, Medical Division, National Research Center, El-Behouth St., Giza, Egypt
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Guo B, Zhang W, Xu S, Lou J, Wang S, Men X. GSK-3β mediates dexamethasone-induced pancreatic β cell apoptosis. Life Sci 2015; 144:1-7. [PMID: 26606859 DOI: 10.1016/j.lfs.2015.11.017] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Revised: 10/29/2015] [Accepted: 11/19/2015] [Indexed: 01/02/2023]
Abstract
AIMS Glucocorticoids, such as dexamethasone, are widely used anti-inflammatory drugs. Their use is frequently associated with the development of steroid- associated diabetes. Pancreatic β-cell dysfunction has been suggested to be one of the main causes of steroid-associated diabetes. However, the mechanism is not fully understood. Glycogen synthase kinase-3β (GSK-3β) is a multifunctional serine/threonine kinase and plays an important role in energy metabolism, cell growth and apoptosis. Therefore, the contribution of GSK-3β in dexamethasone-induced pancreatic β-cell apoptosis was determined in the present study. MAIN METHODS The effect of dexamethasone treatment on rat pancreatic β-cell line (INS-1) apoptosis (determined by TUNEL and Flow Cytometry), generation of reactive oxidative stress (ROS), and the phosphorylation status of GSK-3β was determined. The inhibitory effect of GSK-3β inhibitor-lithium chloride (LiCl) on dexamethasone-induced β-cell apoptosis was also evaluated. KEY FINDINGS Dexamethasone (0.1 μM) treatment induced INS-1 apoptosis, which was associated with increased GSK-3β activation and increased NOX4-derived ROS generation. Pretreatment of INS-1 with LiCl inhibited dexamethasone induced ROS generation and INS-1 apoptosis. SIGNIFICANCE This study provides a new mechanism of Dex induced pancreatic β cell apoptosis and may serve as a new therapeutic option for treating GC induced diabetes.
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Affiliation(s)
- Bin Guo
- Department of Pathophysiology, North China University of Science and Technology,Tangshan 063000, People's Republic of China
| | - Wenjian Zhang
- Institute of Clinical Medical Sciences, China-Japan Friendship Hospital, Beijing 100029, People's Republic of China
| | - Shiqing Xu
- Institute of Clinical Medical Sciences, China-Japan Friendship Hospital, Beijing 100029, People's Republic of China
| | - Jinning Lou
- Institute of Clinical Medical Sciences, China-Japan Friendship Hospital, Beijing 100029, People's Republic of China
| | - Shuxia Wang
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY 40536, USA.
| | - Xiuli Men
- Department of Pathophysiology, North China University of Science and Technology,Tangshan 063000, People's Republic of China.
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Wolden-Kirk H, Overbergh L, Gysemans C, Brusgaard K, Naamane N, Van Lommel L, Schuit F, Eizirik DL, Christesen H, Mathieu C. Unraveling the effects of 1,25OH2D3 on global gene expression in pancreatic islets. J Steroid Biochem Mol Biol 2013; 136:68-79. [PMID: 23137852 DOI: 10.1016/j.jsbmb.2012.10.017] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Revised: 10/19/2012] [Accepted: 10/20/2012] [Indexed: 01/01/2023]
Abstract
INTRODUCTION Vitamin D deficiency has been linked to type 1 and 2 diabetes, whereas supplementation may prevent both diseases. However, the extent of the effects of vitamin D or its metabolites directly on pancreatic islets is still largely unknown. The aim of the present study was to investigate how active vitamin D, 1,25(OH)2D3, affects beta cells directly by establishing its effects on global gene expression in healthy murine islets. MATERIALS AND METHODS Pancreatic islets were isolated from 2 to 3 week old C57BL/6 mice and cultured in vitro with 1,25(OH)2D3 or vehicle for 6 and 24h. Total RNA was extracted from the islets and the effects on global gene expression were analyzed using Affymetrix microarrays. RESULTS AND DISCUSSION Exposure to 1,25(OH)2D3 compared to vehicle resulted in 306 and 151 differentially expressed genes after 6 and 24h, respectively (n=4, >1.3-fold, p<0.02). Of these 220 were up-regulated, whereas 86 displayed a decreased expression after 6h. Furthermore, expression levels were increased for 124 and decreased for 27 genes following 24h of exposure. Formation of intercellular junctions, cytoskeletal organization, and intracellular trafficking as well as lipid metabolism and ion transport were among the most affected gene classes. Effects on several genes already identified as being part of vitamin D signaling in other cell types were observed along with genes known to affect insulin release, although with our assay we were not able to detect any effects of 1,25(OH)2D3 on glucose-stimulated insulin release from healthy pancreatic islets. CONCLUSION The effects of 1,25(OH)2D3 on the expression of cytoskeletal and intracellular trafficking genes along with genes involved in ion transport may influence insulin exocytosis. However, an effect of 1,25(OH)2D3 on insulin release could not be detected for healthy islets in contrast to islets subjected to pathological conditions such as cytokine exposure and vitamin D deficiency as suggested by other studies. Thus, in addition to previously identified tolerogenic effects on the immune system, 1,25(OH)2D3 may affect basic functions of pancreatic beta cells, with the potential to render them more resistant to the detrimental conditions encountered during type 1 and 2 diabetes. This article is part of a Special Issue entitled 'Vitamin D Workshop'.
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Affiliation(s)
- H Wolden-Kirk
- Clinical and Experimental Endocrinology, University Hospital Gasthuisberg, Catholic University of Leuven, Herestraat 49, Box 902, B-3000 Leuven, Belgium.
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Khadrawy YA, AboulEzz HS, Ahmed NA, Mohammed HS. The Anticonvulant Effect of Cooling in Comparison to α-Lipoic Acid: A Neurochemical Study. Neurochem Res 2013; 38:906-15. [DOI: 10.1007/s11064-013-0995-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Revised: 01/28/2013] [Accepted: 01/31/2013] [Indexed: 11/29/2022]
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Beaudry JL, Riddell MC. Effects of glucocorticoids and exercise on pancreatic β-cell function and diabetes development. Diabetes Metab Res Rev 2012; 28:560-73. [PMID: 22556149 DOI: 10.1002/dmrr.2310] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Peripheral insulin resistance and pancreatic β-cell dysfunction are hallmark characteristics of type 2 diabetes mellitus (T2DM). Several contributing factors have been proposed to promote these two defects in individuals with T2DM, including physical inactivity and chronic exposure to various psychosocial factors that increase the body's exposure to glucocorticoids, the main stress hormones in humans. Initially, β-cells have been shown to adapt to these stimuli, a phenomenon known as β-cell 'compensation'. However, long-term exposure to these physiologic and psychological stressors induces islet failure. Interestingly, glucocorticoids stimulate β-cell mass growth in parallel with promoting severe insulin resistance, the former being an important adaptive response to the latter. The direct relationship between glucocorticoids and β-cell dysfunction remains a controversial area of research. Elevations in circulating and/or tissue specific glucocorticoids have been associated with the development of obesity and T2DM in human and rodent models; however, the progression from insulin resistance to overt T2DM is highly disputed with respect to the in vivo and in vitro effects of glucocorticoids. Paradoxically, both intermittent physical stress and regular exercise alleviate insulin resistance and help to preserve β-cell mass, potentially by lowering glucocorticoid levels. Recent studies have begun to examine the mechanisms of intermittent and chronic glucocorticoid exposure and regular exercise in altering β-cell function. This review highlights recent discoveries on the physiological regulation of β-cells and diabetes development in conditions of elevated glucocorticoids, regular exercise and intermittent stress.
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Affiliation(s)
- Jacqueline L Beaudry
- School of Kinesiology and Health Science, York University, North York, Ontario, Canada
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Serum- and glucocorticoid-inducible kinase 1 in the regulation of renal and extrarenal potassium transport. Clin Exp Nephrol 2011; 16:73-80. [DOI: 10.1007/s10157-011-0488-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2009] [Accepted: 04/08/2010] [Indexed: 01/24/2023]
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Ibraghimov-Beskrovnaya O, Natoli TA. mTOR signaling in polycystic kidney disease. Trends Mol Med 2011; 17:625-33. [PMID: 21775207 DOI: 10.1016/j.molmed.2011.06.003] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Revised: 04/16/2011] [Accepted: 06/07/2011] [Indexed: 12/15/2022]
Abstract
Polycystic kidney diseases (PKDs) comprise a large group of genetic disorders characterized by formation of cysts in the kidneys and other organs, ultimately leading to end-stage renal disease. Although PKDs can be caused by mutations in different genes, they converge on a set of common molecular mechanisms involved in cystogenesis and ciliary dysfunction, and can be qualified as ciliopathies. Recent advances in understanding the mechanisms regulating disease progression have led to the development of new therapies that are being tested in both preclinical and clinical trials. In this article, we briefly review a network of molecular pathways of cystogenesis that are regulated by ciliary functions. We discuss the mTOR pathway in depth, highlighting recent progress in understanding its role in PKD and the current results of clinical trials.
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The neuroprotective effect of curcumin and Nigella sativa oil against oxidative stress in the pilocarpine model of epilepsy: a comparison with valproate. Neurochem Res 2011; 36:2195-204. [PMID: 21751034 DOI: 10.1007/s11064-011-0544-9] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/02/2011] [Indexed: 12/18/2022]
Abstract
Oxidative stress has been implicated to play a role in epileptogenesis and pilocarpine-induced seizures. The present study aims to evaluate the antioxidant effects of curcumin, Nigella sativa oil (NSO) and valproate on the levels of malondialdehyde, nitric oxide, reduced glutathione and the activities of catalase, Na⁺, K⁺-ATPase and acetylcholinesterase in the hippocampus of pilocarpine-treated rats. The animal model of epilepsy was induced by pilocarpine and left for 22 days to establish the chronic phase of epilepsy. These animals were then treated with curcumin, NSO or valproate for 21 days. The data revealed evidence of oxidative stress in the hippocampus of pilocarpinized rats as indicated by the increased nitric oxide levels and the decreased glutathione levels and catalase activity. Moreover, a decrease in Na⁺, K⁺-ATPase activity and an increase in acetylcholinesterase activity occurred in the hippocampus after pilocarpine. Treatment with curcumin, NSO or valproate ameliorated most of the changes induced by pilocarpine and restored Na⁺, K⁺-ATPase activity in the hippocampus to control levels. This study reflects the promising anticonvulsant and potent antioxidant effects of curcumin and NSO in reducing oxidative stress, excitability and the induction of seizures in epileptic animals and improving some of the adverse effects of antiepileptic drugs.
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Tumor suppressor gene adenomatous polyposis coli downregulates intestinal transport. Pflugers Arch 2011; 461:527-36. [DOI: 10.1007/s00424-011-0945-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Revised: 02/15/2011] [Accepted: 02/16/2011] [Indexed: 12/21/2022]
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Stefanello FM, Ferreira AGK, Pereira TCB, da Cunha MJ, Bonan CD, Bogo MR, Wyse ATS. Acute and chronic hypermethioninemia alter Na+ K+-ATPase activity in rat hippocampus: prevention by antioxidants. Int J Dev Neurosci 2011; 29:483-8. [PMID: 21354298 DOI: 10.1016/j.ijdevneu.2011.02.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2010] [Revised: 01/21/2011] [Accepted: 02/07/2011] [Indexed: 10/18/2022] Open
Abstract
In the current study we initially investigated the influence of antioxidants (vitamins E plus C) on the effect mediated by acute and chronic administration of methionine (Met) on Na(+),K(+)-ATPase activity in rat hippocampus. We also verified whether the alterations on the enzyme after administration of Met and/or antioxidants were associated with changes in relative expression of Na(+),K(+)-ATPase catalytic subunits (isoforms α1, α2 and α3). For acute treatment, young rats received a single subcutaneous injection of Met or saline (control) and were sacrificed 12 h later. In another set of experiments, rats were pretreated for 1 week with daily intraperitoneal administration of vitamins E (40 mg/kg) and C (100 mg/kg) or saline. After that, rats received a single injection of Met or saline and were killed 12 h later. For chronic treatment, Met was administered to rats from the 6th to the 28th day of life; controls and treated rats were sacrificed 12 h after the last injection. In parallel to chronic treatment, rats received a daily intraperitoneal injection of vitamins E and C from the 6th to the 28th day of life and were killed 12 h after the last injection. Results showed that administration of antioxidants partially prevented the inhibition of enzyme activity caused by acute and chronic hypermethioninemia. Besides, we demonstrated that transcription of catalytic subunits of Na(+),K(+)-ATPase was not altered by chronic and acute exposure to Met and/or vitamins E plus C. These data strongly suggest the oxidative damage as one possible mechanism involved in the reduction of Na(+),K(+)-ATPase activity caused by hypermethioninemia and if confirmed in human beings, we might propose the use of antioxidants as an adjuvant therapy in hypermethioninemic patients.
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Affiliation(s)
- Francieli M Stefanello
- Laboratório de Neuroproteção e Doença Metabólica, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-Anexo, CEP 90035-003, Porto Alegre, RS, Brazil
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de Sales Santos ÍM, da Rocha Tomé A, Feitosa CM, de Souza GF, Feng D, de Freitas RM, Jordán J. Lipoic acid blocks seizures induced by pilocarpine via increases in δ-aminolevulinic dehydratase and Na+, K+-ATPase activity in rat brain. Pharmacol Biochem Behav 2010; 95:88-91. [DOI: 10.1016/j.pbb.2009.12.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Revised: 12/01/2009] [Accepted: 12/14/2009] [Indexed: 11/29/2022]
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Abstract
Compelling evidence is accumulating indicating a pathophysiological role of the serum-and-glucocorticoid-inducible-kinase-1 (SGK1) in the development and complications of diabetes. SGK1 is ubiquitously expressed with exquisitely high transcriptional volatility. Stimulators of SGK1 expression include hyperglycemia, cell shrinkage, ischemia, glucocorticoids and mineralocorticoids. SGK1 is activated by insulin and growth factors via PI3K, 3-phosphoinositide dependent kinase PDK1 and mTOR. SGK1 activates ion channels (including ENaC, TRPV5, ROMK, KCNE1/KCNQ1 and CLCKa/Barttin), carriers (including NCC, NKCC, NHE3, SGLT1 and EAAT3), and the Na(+)/K(+)-ATPase. It regulates the activity of several enzymes (e.g., glycogen-synthase-kinase-3, ubiquitin-ligase Nedd4-2, phosphomannose-mutase-2), and transcription factors (e.g., forkhead-transcription-factor FOXO3a, beta-catenin and NF-kappaB). A common SGK1 gene variant ( approximately 3 - 5% prevalence in Caucasians, approximately 10% in Africans) is associated with increased blood pressure, obesity and type 2 diabetes. In patients suffering from type 2 diabetes, SGK1 presumably contributes to fluid retention and hypertension, enhanced coagulation and increased deposition of matrix proteins leading to tissue fibrosis such as diabetic nephropathy. Accordingly, targeting SGK1 may favourably influence occurrence and course of type 2 diabetes.
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Affiliation(s)
- Florian Lang
- Eberhard-Karls-University of Tuebingen, Department of Physiology, Gmelinstrasse 5, Tuebingen 72076, Germany.
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The physiological impact of the serum and glucocorticoid-inducible kinase SGK1. Curr Opin Nephrol Hypertens 2009; 18:439-48. [PMID: 19584721 DOI: 10.1097/mnh.0b013e32832f125e] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
PURPOSE OF REVIEW The role of serum and glucocorticoid-inducible kinase 1 (SGK1) in renal physiology and pathophysiology is reviewed with particular emphasis on recent advances. RECENT FINDINGS The mammalian target of rapamycin complex 2 has been shown to phosphorylate SGK1 at Ser422 (the so-called hydrophobic motif). Ser397 and Ser401 are two additional SGK1-phosphorylation sites required for maximal SGK1 activity. A 5' variant alternate transcript of human Sgk1 has been identified that is widely expressed and shows improved stability, enhanced membrane association, and greater stimulation of epithelial Na+ transport. SGK1 is essential for optimal processing of the epithelial sodium channel and also regulates the expression of the Na+-Cl- cotransporter. With regard to pathophysiology, SGK1 participates in the stimulation of renal tubular glucose transport in diabetes, the renal profibrotic effect of both angiotensin II and aldosterone, and in fetal programing of arterial hypertension. SUMMARY The outlined recent findings advanced our understanding of the molecular regulation of SGK1 as well as the role of the kinase in renal physiology and the pathophysiology of renal disease and hypertension. Future studies using pharmacological inhibitors of SGK1 will reveal the utility of the kinase as a new therapeutic target.
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Lipoic acid alters delta-aminolevulinic dehydratase, glutathione peroxidase and Na+,K+-ATPase activities and glutathione-reduced levels in rat hippocampus after pilocarpine-induced seizures. Cell Mol Neurobiol 2009; 30:381-7. [PMID: 19798568 DOI: 10.1007/s10571-009-9460-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2009] [Accepted: 09/15/2009] [Indexed: 12/18/2022]
Abstract
In the present study, we investigated the effects of lipoic acid (LA) in the brain oxidative stress caused by pilocarpine-induced seizures in adult rats. Wistar rats were treated with 0.9% saline (i.p., control group), lipoic acid (10 mg/kg, i.p., LA group), pilocarpine (400 mg/kg, i.p., pilocarpine group), and the association of LA (10 mg/kg, i.p.) plus pilocarpine (400 mg/kg, i.p.), 30 min before the administration of LA (LA plus pilocarpine group). After the treatments, all groups were observed for 1 h. The enzyme activities [delta-aminolevulinic dehydratase (delta-ALA-D), glutathione peroxidase (GPx), glutathione reductase (GR), and Na+,K+-ATPase] as well as the glutathione-reduced (GSH) and ascorbic acid (AA) concentrations were measured using spectrophotometric methods, and the results were compared to values obtained from saline and pilocarpine-treated animals. Protective effects of LA were also evaluated on the same parameters. In pilocarpine group, no changes were observed in GPx and GR activities and AA content. Moreover, in the same group, decrease in GSH levels as well as a reduction in delta-ALA-D and Na+,K+-ATPase activities after seizures was observed. In turn, in LA plus pilocarpine group, the appearance of seizures was abolished, and the decreases in delta-ALA-D and Na+,K+-ATPase activities produced by seizures as well as increases in GSH levels and GPx activity were reversed, when compared to the pilocarpine seizing group. The results of the present study demonstrated that preadministration of LA abolished seizure episodes induced by pilocarpine in rat, probably by reducing oxidative stress in rat hippocampus caused by seizures.
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Abstract
Type 2 diabetes mellitus is a complex metabolic disease that is caused by insulin resistance and beta-cell dysfunction. Furthermore, type 2 diabetes has an evident genetic component and represents a polygenic disease. During the last decade, considerable progress was made in the identification of type 2 diabetes risk genes. This was crucially influenced by the development of affordable high-density single nucleotide polymorphism (SNP) arrays that prompted several successful genome-wide association scans in large case-control cohorts. Subsequent to the identification of type 2 diabetes risk SNPs, cohorts thoroughly phenotyped for prediabetic traits with elaborate in vivo methods allowed an initial characterization of the pathomechanisms of these SNPs. Although the underlying molecular mechanisms are still incompletely understood, a surprising result of these pathomechanistic investigations was that most of the risk SNPs affect beta-cell function. This favors a beta-cell-centric view on the genetics of type 2 diabetes. The aim of this review is to summarize the current knowledge about the type 2 diabetes risk genes and their variants' pathomechanisms.
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Affiliation(s)
- Harald Staiger
- Department of Internal Medicine, Division of Endocrinology, Diabetology, Angiology, Nephrology, and Clinical Chemistry, University Hospital Tübingen, D-72076 Tübingen, Germany
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Kim SH, Kim KX, Raveendran NN, Wu T, Pondugula SR, Marcus DC. Regulation of ENaC-mediated sodium transport by glucocorticoids in Reissner's membrane epithelium. Am J Physiol Cell Physiol 2009; 296:C544-57. [PMID: 19144862 DOI: 10.1152/ajpcell.00338.2008] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Reissner's membrane epithelium forms much of the barrier that produces and sustains the large ionic differences between cochlear endolymph and perilymph. We have reported that Reissner's membrane contributes to normal cochlear function by absorbing Na(+) from endolymph via amiloride-sensitive channels in gerbil inner ear. We used mouse Reissner's membrane to 1) identify candidate genes involved in the Na(+) transport pathway, 2) determine whether their level of expression was regulated by the synthetic glucocorticoid dexamethasone, and 3) obtain functional evidence for the physiological importance of these genes. Transcripts were present for alpha-, beta-, and gamma-subunits of epithelial Na(+) channel (ENaC); corticosteroid receptors GR (glucocorticoid receptor) and MR (mineralocorticoid receptor); GR agonist regulator 11beta-hydroxysteroid dehydrogenase (HSD) type 1 (11beta-HSD1); Na(+) transport control components SGK1, Nedd4-2, and WNKs; and K(+) channels and Na(+)-K(+)-ATPase. Expression of the MR agonist regulator 11beta-HSD2 was not detected. Dexamethasone upregulated transcripts for alpha- and beta-subunits of ENaC ( approximately 6- and approximately 3-fold), KCNK1 ( approximately 3-fold), 11beta-HSD1 ( approximately 2-fold), SGK1 ( approximately 2-fold), and WNK4 ( approximately 3-fold). Transepithelial currents from the apical to the basolateral side of Reissner's membrane were sensitive to amiloride (IC(50) approximately 0.7 muM) and benzamil (IC(50) approximately 0.1 muM), but not EIPA (IC(50) approximately 34 muM); amiloride-blocked transepithelial current was not immediately changed by forskolin/IBMX. Currents were reduced by ouabain, lowered bath Na(+) concentration (from 150 to 120 mM), and K(+) channel blockers (XE-991, Ba(2+), and acidification from pH 7.4 to 6.5). Dexamethasone-stimulated current and gene expression were reduced by mifepristone, but not spironolactone. These molecular, pharmacological, and functional observations are consistent with Na(+) absorption by mouse Reissner's membrane, which is mediated by apical ENaC and/or other amiloride-sensitive channels, basolateral Na(+)-K(+)-ATPase, and K(+)-permeable channels and is under the control of glucocorticoids. These results provide an understanding and a molecular definition of an important transport function of Reissner's membrane epithelium in the homeostasis of cochlear endolymph.
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Affiliation(s)
- Sung Huhn Kim
- Kansas State Univ., Anatomy & Physiology, 228 Coles Hall, Manhattan, KS 66506-5802, USA
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Friedrich B, Weyrich P, Stancáková A, Wang J, Kuusisto J, Laakso M, Sesti G, Succurro E, Smith U, Hansen T, Pedersen O, Machicao F, Schäfer S, Lang F, Risler T, Ullrich S, Stefan N, Fritsche A, Häring HU. Variance of the SGK1 gene is associated with insulin secretion in different European populations: results from the TUEF, EUGENE2, and METSIM studies. PLoS One 2008; 3:e3506. [PMID: 18985156 PMCID: PMC2575233 DOI: 10.1371/journal.pone.0003506] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Accepted: 09/27/2008] [Indexed: 11/24/2022] Open
Abstract
Hypothesis Serum- and Glucocorticoid-inducible Kinase 1 (SGK1) is involved in the regulation of insulin secretion and may represent a candidate gene for the development of type 2 diabetes mellitus in humans. Methods Three independent European populations were analyzed for the association of SGK1 gene (SGK) variations and insulin secretion traits. The German TUEF project provided the screening population (N = 725), and four tagging SNPs (rs1763527, rs1743966, rs1057293, rs9402571) were investigated. EUGENE2 (N = 827) served as a replication cohort for the detected associations. Finally, the detected associations were validated in the METSIM study, providing 3798 non-diabetic and 659 diabetic (type 2) individuals. Results Carriers of the minor G allele in rs9402571 had significantly higher C-peptide levels in the 2 h OGTT (+10.8%, p = 0.04; dominant model) and higher AUCC-Peptide/AUCGlc ratios (+7.5%, p = 0.04) compared to homozygous wild type TT carriers in the screening population. As interaction analysis for BMI×rs9402571 was significant (p = 0.04) for the endpoint insulin secretion, we stratified the TUEF cohort for BMI, using a cut off point of BMI = 25. The effect on insulin secretion only remained significant in lean TUEF participants (BMI≤25). This finding was replicated in lean EUGENE2 rs9402571 minor allele carriers, who had a significantly higher AUCIns/AUCGlc (TT: 226±7, XG: 246±9; p = 0.019). Accordingly, the METSIM trial revealed a lower prevalence of type 2 diabetes (OR: 0.85; 95%CI: 0.71–1.01; p = 0.065, dominant model) in rs9402571 minor allele carriers. Conclusions The rs9402571 SGK genotype associates with increased insulin secretion in lean non-diabetic TUEF/EUGENE2 participants and with lower diabetes prevalence in METSIM. Our study in three independent European populations supports the conclusion that SGK variability affects diabetes risk.
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Affiliation(s)
- Björn Friedrich
- Department of Internal Medicine, Division of Endocrinology, Diabetology, Vascular Medicine, Nephrology and Clinical Chemistry, University of Tübingen, Tübingen, Germany
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Activation of the Na+/K+-ATPase by insulin and glucose as a putative negative feedback mechanism in pancreatic beta-cells. Pflugers Arch 2008; 457:1351-60. [PMID: 18836740 DOI: 10.1007/s00424-008-0592-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2008] [Revised: 09/14/2008] [Accepted: 09/18/2008] [Indexed: 10/21/2022]
Abstract
Pancreatic beta-cells of sulfonylurea receptor type 1 knock-out (SUR1(-/-)) mice exhibit an oscillating membrane potential (V (m)) demonstrating that hyper-polarisation occurs despite the lack of K(ATP) channels. We hypothesize that glucose activates the Na(+)/K(+)-ATPase thus increasing a hyper-polarising current. Elevating glucose in SUR1(-/-) beta-cells resulted in a transient fall in V (m) and [Ca(2+)](c) independent of sarcoplasmic and endoplasmic reticulum Ca(2+)-activated ATPase (SERCA) activation. This was not affected by K(+) channel blockade but inhibited by ATP depletion and by ouabain. Increasing glucose also reduced [Na(+)](c), an effect reversed by ouabain. Exogenously applied insulin decreased [Na(+)](c) and hyper-polarised V (m). Inhibiting insulin signalling in SUR1(-/-) beta-cells blunted the glucose-induced decrease of [Ca(2+)](c). Tolbutamide (1 mmol/l) disclosed the SERCA-independent effect of glucose on [Ca(2+)](c) in wild-type beta-cells. The data show that in SUR1(-/-) beta-cells, glucose activates the Na(+)/K(+)-ATPase presumably by increasing [ATP](c). Insulin can also stimulate the pump and potentiate the effect of glucose. Pathways involving the pump may thus serve as potential drug targets in certain metabolic disorders.
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Bibliography. Current world literature. Growth and development. Curr Opin Endocrinol Diabetes Obes 2008; 15:79-101. [PMID: 18185067 DOI: 10.1097/med.0b013e3282f4f084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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