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Journal of Diabetes Research
Volume 2016, Article ID 1632061, 9 pages
http://dx.doi.org/10.1155/2016/1632061
Research Article

Fatty Liver and Insulin Resistance in the Liver-Specific Knockout Mice of Mitogen Inducible Gene-6

1Research Center for Drug Discovery Technology, Division of Drug Discovery Research, Korea Research Institute of Chemical Technology, Daejeon, Republic of Korea
2Department of Drug Development and Discovery, Graduate School of New Drug Development and Discovery, Chungnam National University, Daejeon, Republic of Korea
3Department of Internal Medicine, Chungnam National University School of Medicine, Daejeon, Republic of Korea

Received 11 April 2016; Revised 21 October 2016; Accepted 24 October 2016

Academic Editor: Hiroshi Okamoto

Copyright © 2016 Byung Kil Park et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Mitogen inducible gene-6 (Mig-6) is a feedback inhibitor of epidermal growth factor receptor (EGFR) signaling pathway. The liver-specific knockout mice of the Mig-6 gene (Mig-6d/d) showed hepatomegaly and increased hypercholesterolemia. In this study, the biomarkers of insulin resistance and the effects of high-fat diets in the wild (Mig-6f/f) and Mig-6d/d mice were analyzed. The fasting plasma concentrations of glucose, triglyceride, cholesterols, free fatty acids, and HOMA-IR were measured and the glucose tolerance and insulin resistance tests were performed in the 25-week-old Mig-6f/f and the Mig-6d/d mice. The protein levels of active insulin receptor, glucose 6-phosphatase, and phosphoenolpyruvate carboxykinase were analyzed in the liver and fat. The fasting plasma cholesterol and glucose concentration were higher in the Mig-6d/d mice than the Mig-6f/f mice with increased fat deposition in the liver. But the Mig-6d/d mice had the improved glucose intolerance and insulin resistance without increased amount of phosphoinsulin receptor after insulin infusion in the liver. The hepatic concentration of phosphoenolpyruvate carboxykinase was increased in fasting Mig-6d/d mice. The feeding of high-fat diet accelerated the plasma lipids profiles and HOMA-IR in the Mig-6d/d mice but had no differential effects in oral glucose tolerance test and insulin tolerance test in both genotypes. These results suggest that the activated EGFR signaling might increase the fasting plasma glucose concentration through inducing the hepatic steatosis and the improved whole-body insulin resistance in the KO mice be caused by decreased adipogenesis in fat tissues.