Hypoxia increases thrombospondin-1 transcript and protein in cultured endothelial cells.
The exposure of endothelial cells to hypoxic environments regulates the expression of a number of genes with products that are vasoactive or mitogenic for vascular tissue, including platelet-derived growth factor, endothelin-1, and endothelial nitric oxide synthase. Hypoxia is also known to alter the adhesive properties of endothelium toward a variety of blood cell types. Thrombospondin-1 (TSP-1) is a glycoprotein with major roles in cellular adhesion and vascular smooth muscle proliferation and migration. We report here that hypoxia induces TSP-1 gene and protein expression. Oxygen tensions of < or =30 torr resulted in TSP-1 transcript induction initially apparent at 1 to 6 hours, with maximal induction (6.5-fold+/-1.2-fold) within 24 to 48 hours in both human and bovine endothelial cells. TSP-1 protein levels remain elevated after 72 hours of continuous hypoxic exposure. The induction of TSP-1 steady-state transcript levels is caused in large part, if not entirely, by post-transcriptional stabilization of the TSP-1 mRNA. The TSP-1 induction by hypoxia is a graded and reversible physiologic response and can be mimicked by the use of cobalt chloride or the inhibition of nitric oxide production, suggesting both the involvement of a heme-containing oxygen sensor and a role for the endogenous production of nitric oxide in TSP-1 regulation. The effects of hypoxia both on the stabilization of the TSP-1 transcript and the stimulation of TSP-1 protein production are completely inhibited by arginine butyrate.
Phelan
M W
MW
Cancer Research Center and Department of Medicine, Boston University School of Medicine, MA 02118, USA.
Forman
L W
LW
Perrine
S P
SP
Faller
D V
DV
D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D002087:Butyrates / Q000494:pharmacology; D002417:Cattle; D002478:Cells, Cultured; D003035:Cobalt / Q000494:pharmacology; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D000860:Hypoxia / Q000378:metabolism*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D010100:Oxygen / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D019700:Thrombospondin 1 / Q000235:genetics* / Q000378:metabolism*
D002087:Butyrates; D006877:Hydroxamic Acids; D012333:RNA, Messenger; D019700:Thrombospondin 1; D003609:Dactinomycin; D003035:Cobalt; C012589:trichostatin A; D001120:Arginine; D003513:Cycloheximide; C018021:cobaltous chloride; C033018:arginine butyrate; D010100:Oxygen; D019331:NG-Nitroarginine Methyl Ester