title: AMPK-dependent repression of hepatic gluconeogenesis via disruption of CREB.CRTC2 complex by orphan nuclear receptor small heterodimer partner.
abstract: Orphan nuclear receptor small heterodimer partner (SHP) plays a key role in transcriptional repression of gluconeogenic enzyme gene expression. Here, we show that SHP inhibited protein kinase A-mediated transcriptional activity of cAMP-response element-binding protein (CREB), a major regulator of glucose metabolism, to modulate hepatic gluconeogenic gene expression. Deletion analysis of phosphoenolpyruvate carboxykinase (PEPCK) promoter demonstrated that SHP inhibited forskolin-mediated induction of PEPCK gene transcription via inhibition of CREB transcriptional activity. In vivo imaging demonstrated that SHP inhibited CREB-regulated transcription coactivator 2 (CRTC2)-mediated cAMP-response element-driven promoter activity. Furthermore, overexpression of SHP using adenovirus SHP decreased CRTC2-dependent elevations in blood glucose levels and PEPCK or glucose-6-phosphatase (G6Pase) expression in mice. SHP and CREB physically interacted and were co-localized in vivo. Importantly, SHP inhibited both wild type CRTC2 and S171A (constitutively active form of CRTC2) coactivator activity and disrupted CRTC2 recruitment on the PEPCK gene promoter. In addition, metformin or overexpression of a constitutively active form of AMPK (Ad-CA-AMPK) inhibited S171A-mediated PEPCK and G6Pase gene expression, and hepatic glucose production and knockdown of SHP partially relieved the metformin- and Ad-CA-AMPK-mediated repression of hepatic gluconeogenic enzyme gene expression in primary rat hepatocytes. In conclusion, our results suggest that a delayed effect of metformin-mediated induction of SHP gene expression inhibits CREB-dependent hepatic gluconeogenesis.
authors.affiliation: Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju 500-757, Republic of Korea.
authors.forename: Ji-Min
authors.initials: JM
authors.lastname: Lee
authors.forename: Woo-Young
authors.initials: WY
authors.lastname: Seo
authors.forename: Kwang-Hoon
authors.initials: KH
authors.lastname: Song
authors.forename: Dipanjan
authors.initials: D
authors.lastname: Chanda
authors.forename: Yong Deuk
authors.initials: YD
authors.lastname: Kim
authors.forename: Don-Kyu
authors.initials: DK
authors.lastname: Kim
authors.forename: Min-Woo
authors.initials: MW
authors.lastname: Lee
authors.forename: Dongryeol
authors.initials: D
authors.lastname: Ryu
authors.forename: Yong-Hoon
authors.initials: YH
authors.lastname: Kim
authors.forename: Jung-Ran
authors.initials: JR
authors.lastname: Noh
authors.forename: Chul-Ho
authors.initials: CH
authors.lastname: Lee
authors.forename: John Y L
authors.initials: JY
authors.lastname: Chiang
authors.forename: Seung-Hoi
authors.initials: SH
authors.lastname: Koo
authors.forename: Hueng-Sik
authors.initials: HS
authors.lastname: Choi
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D005943:Gluconeogenesis / Q000187:drug effects / Q000502:physiology*; D005952:Glucose-6-Phosphatase / Q000235:genetics / Q000378:metabolism; D022781:Hepatocytes / Q000166:cytology / Q000502:physiology*; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology; D008687:Metformin / Q000494:pharmacology; D051379:Mice; D019764:Phosphoenolpyruvate Carboxykinase (ATP) / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D051381:Rats; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*
chemical_list: C545700:CRTC2 protein, rat; D017362:Cyclic AMP Response Element-Binding Protein; D007004:Hypoglycemic Agents; D018160:Receptors, Cytoplasmic and Nuclear; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; C099713:nuclear receptor subfamily 0, group B, member 2; D008687:Metformin; D055372:AMP-Activated Protein Kinases; D005952:Glucose-6-Phosphatase; D019764:Phosphoenolpyruvate Carboxykinase (ATP)