title: Post-transcriptional regulation of vascular endothelial growth factor by hypoxia.
abstract: The major control point for the hypoxic induction of the vascular endothelial growth factor (VEGF) gene is the regulation of the steady-state level of the mRNA. We previously demonstrated a discrepancy between the transcription rate and the steady-state mRNA level induced by hypoxia. This led us to examine the post-transcriptional regulation of VEGF expression. Actinomycin D experiments revealed that hypoxia increased VEGF mRNA half-life from 43 +/- 6 min to 106 +/- 9 min. Using an in vitro mRNA degradation assay, the half-life of VEGF mRNA 3'-untranslated region (UTR) transcripts were also found to be increased when incubated with hypoxic versus normoxic extracts. Both cis-regulatory elements involved in VEGF mRNA degradation under normoxic conditions and in increased stabilization under hypoxic conditions were mapped using this degradation assay. A hypoxia-induced protein(s) was found that bound to the sequences in the VEGF 3'-UTR which mediated increased stability in the degradation assay. Furthermore, genistein, a tyrosine kinase inhibitor, blocked the hypoxia-induced stabilization of VEGF 3'-UTR transcripts and inhibited hypoxia-induced protein binding to the VEGF 3'-UTR. These findings demonstrate a significant post-transcriptional component to the regulation of VEGF.
authors.affiliation: Cardiology Division, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
authors.forename: A P
authors.initials: AP
authors.lastname: Levy
authors.forename: N S
authors.initials: NS
authors.lastname: Levy
authors.forename: M A
authors.initials: MA
authors.lastname: Goldberg
mesh_terms: D000818:Animals; D001483:Base Sequence; D015687:Cell Hypoxia; D002474:Cell-Free System; D016228:Endothelial Growth Factors / Q000378:metabolism*; D019833:Genistein; D007529:Isoflavones / Q000494:pharmacology; D008222:Lymphokines / Q000378:metabolism*; D008969:Molecular Sequence Data; D016716:PC12 Cells; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D014158:Transcription, Genetic / Q000187:drug effects; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
chemical_list: D016228:Endothelial Growth Factors; D007529:Isoflavones; D008222:Lymphokines; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D019833:Genistein