Caifeng Yan1,2, Jinfeng Chen3, Min Li2, Wenying Xuan4, Dongming Su4, Hui You2, Yujie Huang2, Nuoqi Chen3, Xiubin Liang5. 1. Department of Endocrinology, Clinical Medical College of Yangzhou University, Yangzhou, China. 2. Department of Pathophysiology, Jiangsu Key Laboratory of Xenotransplantation, Nanjing Medical University, Nanjing, 210029, Jiangsu, China. 3. Department of Endocrinology, Zhangzhou Affiliated Hospital of Fujian Medical University, Zhangzhou, China. 4. Center of Pathology and Clinical Laboratory, Mingde Hospital of Nanjing Medical University, Nanjing, China. 5. Department of Pathophysiology, Jiangsu Key Laboratory of Xenotransplantation, Nanjing Medical University, Nanjing, 210029, Jiangsu, China. liangxiubin@njmu.edu.cn.
Abstract
AIM/HYPOTHESIS: MicroRNA-9 (miR-9) is involved in the regulation of pancreatic beta cell function. However, its role in gluconeogenesis is still unclear. Our objective was to investigate the role of miR-9 in hepatic glucose production (HGP). METHODS: MiR-9 expression was measured in livers of high-fat diet (HFD) mice and ob/ob mice. The methylation status of the miR-9-3 promoter regions in hepatocytes was determined by the methylation-specific PCR procedure. The binding activity of DNA methyltransferase (DNMT)1, DNMT3a and DNMT3b on the miR-9-3 promoter was detected by chromatin immunoprecipitation (ChIP) and quantitative real-time PCR assays. HGP was evaluated in vitro and in vivo. Glucose tolerance, insulin tolerance and pyruvate tolerance tests were also performed. RESULTS: Reduced miR-9 expression and hypermethylation of the miR-9-3 promoter were observed in the livers of obese mice. Further study showed that the binding of DNMT1, but not of DNMT3a and DNMT3b, to the miR-9-3 promoter was increased in hepatocytes from ob/ob mice. Knockdown of DNMT1 alleviated the decrease in hepatic miR-9 expression in vivo and in vitro. Overexpression of hepatic miR-9 improved insulin sensitivity in obese mice and inhibited HGP. In addition, deletion of hepatic miR-9 led to an increase in random and fasting blood glucose levels in lean mice. Importantly, silenced forkhead box O1 (FOXO1) expression reversed the gluconeogenesis and glucose production in hepatocytes induced by miR-9 deletion. CONCLUSIONS/ INTERPRETATION: Our observations suggest that the decrease in miR-9 expression contributes to an inappropriately activated gluconeogenesis in obese mice.
AIM/HYPOTHESIS: MicroRNA-9 (miR-9) is involved in the regulation of pancreatic beta cell function. However, its role in gluconeogenesis is still unclear. Our objective was to investigate the role of miR-9 in hepatic glucose production (HGP). METHODS: MiR-9 expression was measured in livers of high-fat diet (HFD) mice and ob/ob mice. The methylation status of the miR-9-3 promoter regions in hepatocytes was determined by the methylation-specific PCR procedure. The binding activity of DNA methyltransferase (DNMT)1, DNMT3a and DNMT3b on the miR-9-3 promoter was detected by chromatin immunoprecipitation (ChIP) and quantitative real-time PCR assays. HGP was evaluated in vitro and in vivo. Glucose tolerance, insulin tolerance and pyruvate tolerance tests were also performed. RESULTS: Reduced miR-9 expression and hypermethylation of the miR-9-3 promoter were observed in the livers of obesemice. Further study showed that the binding of DNMT1, but not of DNMT3a and DNMT3b, to the miR-9-3 promoter was increased in hepatocytes from ob/ob mice. Knockdown of DNMT1 alleviated the decrease in hepatic miR-9 expression in vivo and in vitro. Overexpression of hepatic miR-9 improved insulin sensitivity in obesemice and inhibited HGP. In addition, deletion of hepatic miR-9 led to an increase in random and fasting blood glucose levels in lean mice. Importantly, silenced forkhead box O1 (FOXO1) expression reversed the gluconeogenesis and glucose production in hepatocytes induced by miR-9 deletion. CONCLUSIONS/ INTERPRETATION: Our observations suggest that the decrease in miR-9 expression contributes to an inappropriately activated gluconeogenesis in obesemice.
Entities:
Keywords:
DNA methylation; FOXO1; Insulin resistance; MicroRNA-9
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