title: Hypoxia-inducible factors regulate human and rat cystathionine β-synthase gene expression.
abstract: Increased catalytic activity of CBS (cystathionine β-synthase) was recently shown to mediate vasodilation of the cerebral microcirculation, which is initiated within minutes of the onset of acute hypoxia. To test whether chronic hypoxia was a stimulus for increased CBS expression, U87-MG human glioblastoma and PC12 rat phaeochromocytoma cells were exposed to 1% or 20% O2 for 24-72 h. CBS mRNA and protein expression were increased in hypoxic cells. Hypoxic induction of CBS expression was abrogated in cells transfected with vector encoding shRNA targeting HIF (hypoxia-inducible factor) 1α or 2α. Exposure of rats to hypobaric hypoxia (0.35 atm; 1 atm=101.325 kPa) for 3 days induced increased CBS mRNA, protein and catalytic activity in the cerebral cortex and cerebellum, which was blocked by administration of the HIF inhibitor digoxin. HIF-binding sites, located 0.8 and 1.2 kb 5' to the transcription start site of the human CBS and rat Cbs genes respectively, were identified by ChIP assays. A 49-bp human sequence, which encompassed an inverted repeat of the core HIF-binding site, functioned as a hypoxia-response element in luciferase reporter transcription assays. Thus HIFs mediate tissue-specific CBS expression, which may augment cerebral vasodilation as an adaptive response to chronic hypoxia.
authors: Naoharu
authors: N
authors: Takano
authors: §Institute for Integrative Physiology and Center for Systems Biology of O2 Sensing, University of Chicago, Chicago, IL 60637, U.S.A.
authors: Ying-Jie
authors: YJ
authors: Peng
authors: §Institute for Integrative Physiology and Center for Systems Biology of O2 Sensing, University of Chicago, Chicago, IL 60637, U.S.A.
authors: Ganesh K
authors: GK
authors: Kumar
authors: Weibo
authors: W
authors: Luo
authors: Hongxia
authors: H
authors: Hu
authors: Larissa A
authors: LA
authors: Shimoda
authors: ‡Department of Biochemistry, School of Medicine, Keio University, Tokyo 160-8582, Japan.
authors: Makoto
authors: M
authors: Suematsu
authors: §Institute for Integrative Physiology and Center for Systems Biology of O2 Sensing, University of Chicago, Chicago, IL 60637, U.S.A.
authors: Nanduri R
authors: NR
authors: Prabhakar
authors: Gregg L
authors: GL
authors: Semenza
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000502:physiology*; D001921:Brain / Q000098:blood supply; D002478:Cells, Cultured; D003541:Cystathionine beta-Synthase / Q000096:biosynthesis* / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic; D057809:HEK293 Cells; D006801:Humans; D002534:Hypoxia, Brain / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D051793:Hypoxia-Inducible Factor 1 / Q000502:physiology; D008297:Male; D016716:PC12 Cells; D051381:Rats; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D014018:Tissue Distribution / Q000235:genetics; D014664:Vasodilation / Q000235:genetics
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D003541:Cystathionine beta-Synthase; D051793:Hypoxia-Inducible Factor 1