title: Diabetes-linked transcription factor HNF4α regulates metabolism of endogenous methylarginines and β-aminoisobutyric acid by controlling expression of alanine-glyoxylate aminotransferase 2.
abstract: Elevated levels of circulating asymmetric and symmetric dimethylarginines (ADMA and SDMA) predict and potentially contribute to end organ damage in cardiovascular diseases. Alanine-glyoxylate aminotransferase 2 (AGXT2) regulates systemic levels of ADMA and SDMA, and also of beta-aminoisobutyric acid (BAIB)-a modulator of lipid metabolism. We identified a putative binding site for hepatic nuclear factor 4 α (HNF4α) in AGXT2 promoter sequence. In a luciferase reporter assay we found a 75% decrease in activity of Agxt2 core promoter after disruption of the HNF4α binding site. Direct binding of HNF4α to Agxt2 promoter was confirmed by chromatin immunoprecipitation assay. siRNA-mediated knockdown of Hnf4a led to an almost 50% reduction in Agxt2 mRNA levels in Hepa 1-6 cells. Liver-specific Hnf4a knockout mice exhibited a 90% decrease in liver Agxt2 expression and activity, and elevated plasma levels of ADMA, SDMA and BAIB, compared to wild-type littermates. Thus we identified HNF4α as a major regulator of Agxt2 expression. Considering a strong association between human HNF4A polymorphisms and increased risk of type 2 diabetes our current findings suggest that downregulation of AGXT2 and subsequent impairment in metabolism of dimethylarginines and BAIB caused by HNF4α deficiency might contribute to development of cardiovascular complications in diabetic patients.
authors.affiliation: Department of Physiology, Saint Petersburg State University, 199034 Saint Petersburg, Russia.
authors.forename: Dmitry V
authors.initials: DV
authors.lastname: Burdin
authors.affiliation: Department of Biochemistry, Saint Petersburg State University, 199034 Saint Petersburg, Russia.
authors.forename: Alexey A
authors.initials: AA
authors.lastname: Kolobov
authors.affiliation: National Cancer Institute, NIH, Bethesda, MD, 20892, USA.
authors.forename: Chad
authors.initials: C
authors.lastname: Brocker
authors.affiliation: The Rockefeller University, New York, NY, 10065, USA.
authors.forename: Alexey A
authors.initials: AA
authors.lastname: Soshnev
authors.affiliation: Stanford University School of Medicine, Stanford, CA, 94305, USA.
authors.forename: Nikolay
authors.initials: N
authors.lastname: Samusik
authors.affiliation: Institute of Highly Pure Biopreparations, 197110 Saint Petersburg, Russia.
authors.forename: Anton V
authors.initials: AV
authors.lastname: Demyanov
authors.affiliation: University Center for Vascular Medicine, Technische Universität Dresden, 01307 Dresden, Germany.
authors.forename: Silke
authors.initials: S
authors.lastname: Brilloff
authors.affiliation: University Center for Vascular Medicine, Technische Universität Dresden, 01307 Dresden, Germany.
authors.forename: Natalia
authors.initials: N
authors.lastname: Jarzebska
authors.affiliation: Institute of Clinical Pharmacology, Otto-von-Guericke University, 39120 Magdeburg, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Martens-Lobenhoffer
authors.affiliation: Institute of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany.
authors.forename: Maren
authors.initials: M
authors.lastname: Mieth
authors.affiliation: Institute of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander-University Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany.
authors.forename: Renke
authors.initials: R
authors.lastname: Maas
authors.affiliation: Department of Internal Medicine III, University Hospital Carl Gustav Carus, Technische Universität Dresden, 01307 Dresden, Germany.
authors.forename: Stefan R
authors.initials: SR
authors.lastname: Bornstein
authors.affiliation: Institute of Clinical Pharmacology, Otto-von-Guericke University, 39120 Magdeburg, Germany.
authors.forename: Stefanie M
authors.initials: SM
authors.lastname: Bode-Böger
authors.affiliation: National Cancer Institute, NIH, Bethesda, MD, 20892, USA.
authors.forename: Frank
authors.initials: F
authors.lastname: Gonzalez
authors.affiliation: University Center for Vascular Medicine, Technische Universität Dresden, 01307 Dresden, Germany.
authors.forename: Norbert
authors.initials: N
authors.lastname: Weiss
authors.affiliation: University Center for Vascular Medicine, Technische Universität Dresden, 01307 Dresden, Germany.
authors.forename: Roman N
authors.initials: RN
authors.lastname: Rodionov
mesh_terms: D000621:Aminoisobutyric Acids / Q000378:metabolism; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000378:metabolism; D002318:Cardiovascular Diseases / Q000150:complications / Q000235:genetics*; D002460:Cell Line; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000235:genetics*; D005786:Gene Expression Regulation; D051557:Hepatocyte Nuclear Factor 4 / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008099:Liver / Q000473:pathology / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D020641:Polymorphism, Single Nucleotide; D011401:Promoter Regions, Genetic / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D012306:Risk; D000637:Transaminases / Q000235:genetics*
chemical_list: D000621:Aminoisobutyric Acids; D051557:Hepatocyte Nuclear Factor 4; C496593:Hnf4a protein, mouse; D034741:RNA, Small Interfering; C487735:dimethylarginine; C024917:symmetric dimethylarginine; C018524:N,N-dimethylarginine; D001120:Arginine; D000637:Transaminases; C019635:Alanine-glyoxylate transaminase; C033435:3-aminoisobutyric acid