title: cAMP-responsive element-binding protein (CREB)-regulated transcription coactivator 2 (CRTC2) promotes glucagon clearance and hepatic amino acid catabolism to regulate glucose homeostasis.
abstract: cAMP-responsive element-binding protein (CREB)-regulated transcription coactivator 2 (CRTC2) regulates transcription of gluconeogenic genes by specifying targets for the transcription factor CREB in response to glucagon. We used an antisense oligonucleotide directed against CRTC2 in both normal rodents and in rodent models of increased gluconeogenesis to better understand the role of CRTC2 in metabolic disease. In the context of severe hyperglycemia and elevated hepatic glucose production, CTRC2 knockdown (KD) improved glucose homeostasis by reducing endogenous glucose production. Interestingly, despite the known role of CRTC2 in coordinating gluconeogenic gene expression, CRTC2 KD in a rodent model of type 2 diabetes resulted in surprisingly little alteration of glucose production. However, CRTC2 KD animals had elevated circulating concentrations of glucagon and a ∼80% reduction in glucagon clearance. When this phenomenon was prevented with somatostatin or a glucagon-neutralizing antibody, endogenous glucose production was reduced by CRTC2 KD. Additionally, CRTC2 inhibition resulted in reduced expression of several glucagon-induced pyridoxal 5'-phosphate-dependent enzymes that convert amino acids to gluconeogenic intermediates, suggesting that it may control substrate availability as well as gluconeogenic gene expression. CRTC2 is an important regulator of gluconeogenesis with tremendous impact in models of elevated hepatic glucose production. Surprisingly, it is also part of a previously unidentified negative feedback loop that degrades glucagon and regulates amino acid metabolism to coordinately control glucose homeostasis in vivo.
authors.affiliation: Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06536, USA.
authors.forename: Derek M
authors.initials: DM
authors.lastname: Erion
authors.forename: Maya E
authors.initials: ME
authors.lastname: Kotas
authors.forename: Jacob
authors.initials: J
authors.lastname: McGlashon
authors.forename: Shin
authors.initials: S
authors.lastname: Yonemitsu
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Hsiao
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Nagai
authors.forename: Takanori
authors.initials: T
authors.lastname: Iwasaki
authors.forename: Susan F
authors.initials: SF
authors.lastname: Murray
authors.forename: Sanjay
authors.initials: S
authors.lastname: Bhanot
authors.forename: Gary W
authors.initials: GW
authors.lastname: Cline
authors.forename: Varman T
authors.initials: VT
authors.lastname: Samuel
authors.forename: Gerald I
authors.initials: GI
authors.lastname: Shulman
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Gillum
mesh_terms: D000596:Amino Acids / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D057134:Antibodies, Neutralizing / Q000494:pharmacology; D003921:Diabetes Mellitus, Experimental / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D055785:Gene Knockdown Techniques; D005934:Glucagon / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D005943:Gluconeogenesis / Q000187:drug effects / Q000235:genetics; D005947:Glucose / Q000235:genetics / Q000378:metabolism*; D006706:Homeostasis; D008099:Liver / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D011732:Pyridoxal Phosphate / Q000235:genetics / Q000378:metabolism; D051381:Rats; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D057134:Antibodies, Neutralizing; C545700:CRTC2 protein, rat; C504923:Crtc2 protein, mouse; D015534:Trans-Activators; D014157:Transcription Factors; D011732:Pyridoxal Phosphate; D005934:Glucagon; D005947:Glucose
keywords: Amino Acid; CRTC2; Diabetes; Glucagon; Gluconeogenesis; Liver; Physiology