Metformin Inhibits Hepatic Gluconeogenesis Through AMP-Activated Protein Kinase–Dependent Regulation of the Orphan Nuclear Receptor SHP

Metformin Inhibits Hepatic Gluconeogenesis Through AMP-Activated Protein Kinase–Dependent Regulation of the Orphan Nuclear Receptor SHP Yong Deuk Kim 1 , Keun-Gyu Park 2 , Yong-Soo Lee 1 , Yun-Yong Park 1 , Don-Kyu Kim 1 , Balachandar Nedumaran 1 , Won Gu Jang 3 , Won-Jea Cho 4 , Joohun Ha 5 , In-Kyu Lee 3 , Chul-Ho Lee 6 and Hueng-Sik Choi 1 1 Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea 2 Department of Internal Medicine, Keimyung University School of Medicine, Daegu, Republic of Korea 3 Department of Internal Medicine, Kyungpook National University School of Medicine, Daegu, Republic of Korea 4 College of Pharmacy and Research Institute of Drug Development, Chonnam National University, Gwangju, Korea 5 Department of Biochemistry and Molecular Biology, Medical Research Center for Bioreation to Reactive Oxygen Species, Kyung Hee University College of Medicine, Seoul, Republic of Korea 6 Korea Research Institute of Bioscience and Biotechnology, Daejeon, Republic of Korea Address correspondence and reprint requests to Hueng-Sik Choi, PhD, Hormone Research Center, School of Biological Sciences & Technology, Chonnam National University, Gwangju, 500-757, Republic of Korea. E-mail: hsc{at}chonnam.ac.kr Abstract OBJECTIVE —Metformin is an antidiabetic drug commonly used to treat type 2 diabetes. The aim of the study was to determine whether metformin regulates hepatic gluconeogenesis through the orphan nuclear receptor small heterodimer partner (SHP; NR0B2). RESEARCH DESIGN AND METHODS —We assessed the regulation of hepatic SHP gene expression by Northern blot analysis with metformin and adenovirus containing a constitutive active form of AMP-activated protein kinase (AMPK) (Ad-AMPK) and evaluated SHP, PEPCK, and G6Pase promoter activities via transient transfection assays in hepatocytes. Knockdown of SHP using siRNA SHP was conducted to characterize the metformin-induced inhibition of hepatic gluconeogenic gene expression in hepatocytes, and metformin–and adenovirus SHP (Ad-SHP)–mediated hepatic glucose production was measured in B6- Lep ob/ ob mice. RESULTS —Hepatic SHP gene expression was induced by metformin, 5-aminoimidazole-4-carboxamide-1-β- d -ribofuranoside (AICAR), and Ad-AMPK. Metformin-induced SHP gene expression was abolished by adenovirus containing the dominant negative form of AMPK (Ad-DN-AMPK), as well as by compound C. Metformin inhibited hepatocyte nuclear factor