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      Epigenetic repression of miR-17 contributed to di(2-ethylhexyl) phthalate-triggered insulin resistance by targeting Keap1-Nrf2/miR-200a axis in skeletal muscle

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          Abstract

          Rationale: Skeletal muscle insulin resistance is detectable before type 2 diabetes is diagnosed. Exposure to di(2-ethylhexyl) phthalate (DEHP), a typical environmental endocrine-disrupting chemical, is a novel risk factor for insulin resistance and type 2 diabetes. This study aimed to explore insulin signaling regulatory pathway in skeletal muscle of the DEHP-induced insulin-resistant mice and to investigate potential therapeutic strategies for treating insulin resistance.

          Methods: C57BL/6J male mice were exposed to 2 mg/kg/day DEHP for 15 weeks. Whole-body glucose homeostasis, oxidative stress and deregulated miRNA-mediated molecular transduction in skeletal muscle were examined. microRNA (miRNA) interventions based on lentiviruses and adeno-associated viruses 9 (AAV9) were performed.

          Results: Dnmt3a-dependent promoter methylation and lncRNA Malat1-related sponge functions cooperatively downregulated miR-17 in DEHP-exposed skeletal muscle cells. DEHP suppressed miR-17 to disrupt the Keap1-Nrf2 redox system and to activate oxidative stress-responsive Txnip in skeletal muscle. Oxidative stress upregulated miR-200a, which directly targets the 3'UTR of Insr and Irs1, leading to hindered insulin signaling and impaired insulin-dependent glucose uptake in skeletal muscle, ultimately promoting the development of insulin resistance. AAV9-induced overexpression of miR-17 and lentivirus-mediated silencing of miR-200a in skeletal muscle ameliorated whole-body insulin resistance in DEHP-exposed mice.

          Conclusions: The miR-17/Keap1-Nrf2/miR-200a axis contributed to DEHP-induced insulin resistance. miR-17 is a positive regulator, whereas miR-200a is a negative regulator of insulin signaling in skeletal muscle, and both miRNAs have the potential to become therapeutic targets for preventing and treating insulin resistance or type 2 diabetes.

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          Most cited references61

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          miR-200c is upregulated by oxidative stress and induces endothelial cell apoptosis and senescence via ZEB1 inhibition.

          We examined the effect of reactive oxygen species (ROS) on MicroRNAs (miRNAs) expression in endothelial cells in vitro, and in mouse skeletal muscle following acute hindlimb ischemia. Human umbilical vein endothelial cells (HUVEC) were exposed to 200 μM hydrogen peroxide (H(2)O(2)) for 8 to 24 h; miRNAs profiling showed that miR-200c and the co-transcribed miR-141 increased more than eightfold. The other miR-200 gene family members were also induced, albeit to a lower level. Furthermore, miR-200c upregulation was not endothelium restricted, and occurred also on exposure to an oxidative stress-inducing drug: 1,3-bis(2 chloroethyl)-1nitrosourea (BCNU). miR-200c overexpression induced HUVEC growth arrest, apoptosis and senescence; these phenomena were also induced by H(2)O(2) and were partially rescued by miR-200c inhibition. Moreover, miR-200c target ZEB1 messenger RNA and protein were downmodulated by H(2)O(2) and by miR-200c overexpression. ZEB1 knockdown recapitulated miR-200c-induced responses, and expression of a ZEB1 allele non-targeted by miR-200c, prevented miR-200c phenotype. The mechanism of H(2)O(2)-mediated miR-200c upregulation involves p53 and retinoblastoma proteins. Acute hindlimb ischemia enhanced miR-200c in wild-type mice skeletal muscle, whereas in p66(ShcA -/-) mice, which display lower levels of oxidative stress after ischemia, upregulation of miR-200c was markedly inhibited. In conclusion, ROS induce miR-200c and other miR-200 family members; the ensuing downmodulation of ZEB1 has a key role in ROS-induced apoptosis and senescence.
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            Diabetic Downregulation of Nrf2 Activity via ERK Contributes to Oxidative Stress–Induced Insulin Resistance in Cardiac Cells In Vitro and In Vivo

            OBJECTIVE Oxidative stress is implicated in cardiac insulin resistance, a critical risk factor for cardiac failure, but the direct evidence remains missing. This study explored a causal link between oxidative stress and insulin resistance with a focus on a regulatory role of redox sensitive transcription factor NF-E2–related factor 2 (Nrf2) in the cardiac cells in vitro and in vivo. RESEARCH DESIGN AND METHODS Chronic treatment of HL-1 adult cardiomyocyte with hydrogen peroxide led to insulin resistance, reflected by a significant suppression of the insulin-induced glucose uptake. This was associated with an exaggerated phosphorylation of extracellular signal–related kinase (ERK). Although U0126, an ERK inhibitor, enhanced insulin sensitivity and attenuated oxidative stress–induced insulin resistance, LY294002, an inhibitor of phosphoinositide 3-kinase (PI3K), worsened the insulin resistance. Moreover, insulin increased Nrf2 transcriptional activity, which was blocked by LY294002 but enhanced by U0126. Forced activation of Nrf2 by adenoviral over-expression of Nrf2 inhibited the increased ERK activity and recovered the blunted insulin sensitivity on glucose uptake in cardiomyocytes that were chronically treated with H2O2. In the hearts of streptozotocin-induced diabetic mice and diabetic patients Nrf2 expression significantly decreased along with significant increases in 3-nitrotyrosine accumulation and ERK phosphorylation, whereas these pathogenic changes were not observed in the heart of diabetic mice with cardiac-specific overexpression of a potent antioxidant metallothionein. Upregulation of Nrf2 by its activator, Dh404, in cardiomyocytes in vitro and in vivo prevented hydrogen peroxide– and diabetes-induced ERK activation and insulin-signaling downregulation. CONCLUSIONS ERK-mediated suppression of Nrf2 activity leads to the oxidative stress–induced insulin resistance in adult cardiomyocytes and downregulated glucose utilization in the diabetic heart.
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              Concentrations of Urinary Phthalate Metabolites Are Associated with Increased Waist Circumference and Insulin Resistance in Adult U.S. Males

              Background Phthalates impair rodent testicular function and have been associated with anti-androgenic effects in humans, including decreased testosterone levels. Low testosterone in adult human males has been associated with increased prevalence of obesity, insulin resistance, and diabetes. Objectives Our objective in this study was to investigate phthalate exposure and its associations with abdominal obesity and insulin resistance. Methods Subjects were adult U.S. male participants in the National Health and Nutrition Examination Survey (NHANES) 1999–2002. We modeled six phthalate metabolites with prevalent exposure and known or suspected antiandrogenic activity as predictors of waist circumference and log-transformed homeostatic model assessment (HOMA; a measure of insulin resistance) using multiple linear regression, adjusted for age, race/ethnicity, fat and total calorie consumption, physical activity level, serum cotinine, and urine creatinine (model 1); and adjusted for model 1 covariates plus measures of renal and hepatic function (model 2). Metabolites were mono-butyl phthalates (MBP), mono-ethyl phthalate (MEP), mono-(2-ethyl)-hexyl phthalate (MEHP), mono-benzyl phthalate (MBzP), mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), and mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP). Results In model 1, four metabolites were associated with increased waist circumference (MBzP, MEHHP, MEOHP, and MEP; p-values ≤ 0.013) and three with increased HOMA (MBP, MBzP, and MEP; p-values ≤ 0.011). When we also adjusted for renal and hepatic function, parameter estimates declined but all significant results remained so except HOMA-MBP. Conclusions In this national cross-section of U.S. men, concentrations of several prevalent phthalate metabolites showed statistically significant correlations with abdominal obesity and insulin resistance. If confirmed by longitudinal studies, our findings would suggest that exposure to these phthalates may contribute to the population burden of obesity, insulin resistance, and related clinical disorders.
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                Author and article information

                Journal
                Theranostics
                Theranostics
                thno
                Theranostics
                Ivyspring International Publisher (Sydney )
                1838-7640
                2020
                23 July 2020
                : 10
                : 20
                : 9230-9248
                Affiliations
                [1 ]Department of Basic Medical Sciences, School of Medicine, Xiamen University, Xiamen 361102, China.
                [2 ]State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, School of Public Health, Xiamen University, Xiamen 361102, China.
                [3 ]Division of Cancer Research and Training, Department of Internal Medicine, Charles R. Drew University of Medicine and Science, David Geffen UCLA School of Medicine, and UCLA Jonsson Comprehensive Cancer Center, 1748 E. 118th Street, Los Angeles, CA, 90059, USA.
                [4 ]The First Affiliated Hospital of Xiamen University, Xiamen, 361003, China.
                Author notes
                ✉ Corresponding authors: Yi Lin, School of Public Health, Xiamen University, Xiang'an South Road, Xiamen, 361102, China; E-mail: tjlinyi@ 123456xmu.edu.cn ; Tel.: +86-0592-2880677, Jie Wei, School of Medicine, Xiamen University, Xiang'an South Road, Xiamen, 361102, China; E-mail: jiewei@ 123456xmu.edu.cn ; Tel.: +86-0592-2880548 and Heqing Shen, School of Public Health, Xiamen University, Xiang'an South Road, Xiamen, 361102, China; E-mail: hqshen@ 123456xmu.edu.cn .

                #These authors contributed equally to this work.

                Competing Interests: The authors have declared that no competing interest exists.

                Article
                thnov10p9230
                10.7150/thno.45253
                7415800
                32802189
                6ea118b9-1374-4cf7-a05f-023aa21aedd0
                © The author(s)

                This is an open access article distributed under the terms of the Creative Commons Attribution License ( https://creativecommons.org/licenses/by/4.0/). See http://ivyspring.com/terms for full terms and conditions.

                History
                : 24 February 2020
                : 13 July 2020
                Categories
                Research Paper

                Molecular medicine
                environmental endocrine-disrupting chemical,insulin resistance,microrna,oxidative stress,skeletal muscle

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