title: Hypoxia stimulates atrial natriuretic peptide gene expression in cultured atrial cardiocytes.
abstract: The current study tested the hypothesis that hypoxia stimulates atrial natriuretic peptide (ANP) gene expression and secretion in cultured atrial myocytes (AT-1 cells). AT-1 cells were obtained from a transplantable mouse atrial cardiomyocyte tumor lineage. Confluent AT-1 cells were exposed to hypoxia (1% oxygen) or normoxia (21% oxygen) as controls for 6 hours to 7 days. Medium ANP levels were measured by radioimmunoassay, and intracellular ANP gene transcripts were quantified by Northern and slot blot analyses. Exposure to hypoxia resulted in a significant increase in cellular ANP mRNA levels within 36 hours, which peaked (3.6-fold increase) at 2 days after hypoxic exposure, and produced a time-dependent increase in the release of ANP from AT-1 cells for 2 to 7 days. Transfection studies with recombinant DNA constructs that contained fragments of the -3003/+62 sequence of the ANP promoter and the luciferase reporter gene revealed that the regulatory sequences that mediate the hypoxia-induced increase in transcription are located within a region that extends from -638 to -518 bp to the transcriptional start site of the ANP gene. Gel mobility shift assays demonstrated that hypoxia-inducible nuclear proteins that bound to the 120-bp putative hypoxia-responsive elements of the ANP gene were produced during hypoxic exposure. We have thus defined a 120-bp region within the ANP gene promoter that contains hypoxia-responsive elements that might be responsible for the enhancement of ANP gene expression in atrial myocytes during hypoxic exposure.
authors.affiliation: Department of Medicine, University of Alabama at Birmingham 35294-0007, USA.
authors.forename: Y F
authors.initials: YF
authors.lastname: Chen
authors.forename: J
authors.initials: J
authors.lastname: Durand
authors.forename: W C
authors.initials: WC
authors.lastname: Claycomb
mesh_terms: D000818:Animals; D009320:Atrial Natriuretic Factor / Q000096:biosynthesis / Q000235:genetics*; D015687:Cell Hypoxia / Q000502:physiology*; D002470:Cell Survival; D015870:Gene Expression; D006325:Heart Atria / Q000166:cytology / Q000378:metabolism*; D006338:Heart Neoplasms / Q000473:pathology; D051379:Mice; D008822:Mice, Transgenic; D012333:RNA, Messenger / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D012333:RNA, Messenger; D009320:Atrial Natriuretic Factor