title: Hypoxia-inducible factor 1alpha modulates adhesion, migration, and FAK phosphorylation in vascular smooth muscle cells.
abstract: Hypoxia promotes angiogenesis by modulating the transcriptional regulator hypoxia-inducible factor 1alpha (HIF-1alpha). HIF-1alpha is a master regulator of the hypoxic response, and its proangiogenic activities include, but are not limited to, regulation of vascular endothelial growth factor (VEGF). The remodeling of the vasculature during angiogenesis requires an initial destabilization step, which facilitates endothelial sprouting, followed by vessel growth, and restabilization through investment of smooth muscle cells. The complex dynamics of hypoxia-induced angiogenesis prompted us to investigate what aspects of this multi-step process are regulated by HIF-1alpha. To do so, we analyzed the molecular properties of aortic and coronary artery smooth muscle cells in response to forced expression of HIF-1alpha, and by treatment with cobalt chloride, which mimics hypoxia. Our results demonstrate that HIF-1alpha causes a marked reduction in the ability of smooth muscle cells to migrate and adhere to extracellular matrices. Analysis of focal adhesion proteins showed no significant difference in expression or localization of vinculin or focal adhesion kinase (FAK). However, investigation of FAK phosphorylation, a critical mediator of adhesion and migration, revealed tyrosine phosphorylation of FAK is diminished in the presence of HIF-1alpha and cobalt chloride. These results indicate that during hypoxia-induced vessel remodeling, HIF-1alpha functions to dampen adhesion and migration of smooth muscle cells by modulating FAK activity. We suggest that HIF-1alpha expression in smooth muscle cells may augment vessel sprouting by loosening smooth muscle cell attachments to the basement membrane and endothelial cells.
authors.affiliation: Vascular Biology Center and Department of Obstetrics and Gynecology, Medical College of Georgia, 1459 Laney Walker Blvd., Augusta, Georgia 30912, USA.
authors.forename: Katina M
authors.initials: KM
authors.lastname: Corley
authors.forename: Caroline J
authors.initials: CJ
authors.lastname: Taylor
authors.forename: Brenda
authors.initials: B
authors.lastname: Lilly
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D001011:Aorta / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D015153:Blotting, Western; D002417:Cattle; D002448:Cell Adhesion; D002465:Cell Movement; D002478:Cells, Cultured; D003035:Cobalt / Q000494:pharmacology; D018076:DNA, Complementary / Q000378:metabolism; D004730:Endothelium, Vascular / Q000378:metabolism; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000378:metabolism*; D006801:Humans; D000860:Hypoxia; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism / Q000502:physiology*; D015151:Immunoblotting; D047468:Immunoprecipitation; D008156:Luciferases / Q000378:metabolism; D008856:Microscopy, Fluorescence; D009130:Muscle, Smooth / Q000166:cytology / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000166:cytology; D009389:Neovascularization, Pathologic; D010766:Phosphorylation; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014162:Transfection; D014443:Tyrosine / Q000737:chemistry; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D014945:Wound Healing
chemical_list: D018076:DNA, Complementary; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; D003035:Cobalt; D014443:Tyrosine; D008156:Luciferases; D051416:Focal Adhesion Protein-Tyrosine Kinases; C018021:cobaltous chloride