Hypoxic activation of the atrial natriuretic peptide gene promoter through direct and indirect actions of hypoxia-inducible factor-1.
Atrial natriuretic peptide (ANP) is a cardiac peptide, the transcription of which is up-regulated in the ischaemic ventricle. However, the molecular mechanism of ANP induction is unclear. This study demonstrated that ANP mRNA expression in rat ventricular myocardium is induced in an early phase of ischaemia, preceded by hypoxia-inducible factor-1 (HIF-1) alpha expression. The ANP gene was also induced by hypoxia or HIF-1 inducers such as CoCl2 and desferrioxamine in H9c2 and neonatal cardiomyocytes. The 2307 bp 5'-flanking region of the rat ANP gene was cloned and fused to the luciferase gene. Evidence of the promoter activity was only apparent in the myocytes and was induced by hypoxia and HIF-1 inducers. The overexpression of HIF-1alpha markedly enhanced ANP promoter activity, and a dominant-negative isoform completely suppressed it. We demonstrated that the promoter regions are essential for hypoxic ANP induction. One promoter region, containing the HIF-1-binding sequence, is regulated directly by HIF-1. The other region is also activated by HIF-1 despite having no HIF-1-binding sequence. These results suggest that HIF-1 enhances the transactivation of the ANP gene in hypoxic myocytes, implying that stimulation of the ANP promoter by HIF-1 may in fact be responsible for the induction of the ANP gene in ischaemic ventricular myocardium.
Chun
Yang-Sook
YS
Human Genome Research Institute and Cancer Research Institute, BK21 Human Life Sciences, Seoul National University College of Medicine, 28 Yongon-dong, Chongno-gu, Seoul 110-799, South Korea.
Hyun
Ju-Yeon
JY
Kwak
Yong-Geun
YG
Kim
In-San
IS
Kim
Chan-Hyung
CH
Choi
Eunjoo
E
Kim
Myung-Suk
MS
Park
Jong-Wan
JW
D000818:Animals; D009320:Atrial Natriuretic Factor / Q000235:genetics*; D001483:Base Sequence; D015153:Blotting, Western; D002478:Cells, Cultured; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000502:physiology*; D024202:Electrophoretic Mobility Shift Assay; D005786:Gene Expression Regulation / Q000502:physiology*; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007150:Immunohistochemistry; D017202:Myocardial Ischemia / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D009687:Nuclear Proteins / Q000502:physiology*; D011401:Promoter Regions, Genetic; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors; D014481:United States
D017931:DNA Primers; D004268:DNA-Binding Proteins; C497444:Hif1a protein, rat; D051793:Hypoxia-Inducible Factor 1; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D009687:Nuclear Proteins; D014157:Transcription Factors; D009320:Atrial Natriuretic Factor