title: Hypoxia upregulates PGI-synthase and increases PGI₂ release in human vascular cells exposed to inflammatory stimuli.
abstract: Hypoxia affects vascular function and cell metabolism, survival, growth, and motility; these processes are partially regulated by prostanoids. We analyzed the effect of hypoxia and inflammation on key enzymes involved in prostanoid biosynthesis in human vascular cells. In human vascular smooth muscle cells (VSMC), hypoxia and interleukin (IL)-1β synergistically increased prostaglandin (PG)I₂ but not PGE₂ release, thereby increasing the PGI₂/PGE₂ ratio. Concomitantly, these stimuli upregulated cyclooxygenase-2 (COX-2) expression (mRNA and protein) and COX activity. Interestingly, hypoxia enhanced PGI-synthase (PGIS) expression and activity in VSMC and human endothelial cells. Hypoxia did not significantly modify the inducible microsomal-PGE-synthase (mPGES)-1. Hypoxia-inducible factor (HIF)-1α-silencing abrogated hypoxia-induced PGIS upregulation. PGIS transcriptional activity was enhanced by hypoxia; however, the minimal PGIS promoter responsive to hypoxia (-131 bp) did not contain any putative hypoxia response element (HRE), suggesting that HIF-1 does not directly drive PGIS transcription. Serial deletion and site-directed mutagenesis studies suggested several transcription factors participate cooperatively. Plasma levels of the stable metabolite of PGI₂ and PGIS expression in several tissues were also upregulated in mice exposed to hypoxia. These data suggest that PGIS upregulation is part of the adaptive response of vascular cells to hypoxic stress and could play a role in counteracting the deleterious effect of inflammatory stimuli.
authors.affiliation: Angiology, Vascular Biology, and Inflammation Laboratory, Institute of Biomedical Research (IIB-Sant Pau), Barcelona, Spain.
authors.forename: Mercedes
authors.initials: M
authors.lastname: Camacho
authors.forename: Cristina
authors.initials: C
authors.lastname: Rodríguez
authors.forename: Anna
authors.initials: A
authors.lastname: Guadall
authors.forename: Sonia
authors.initials: S
authors.lastname: Alcolea
authors.forename: Mar
authors.initials: M
authors.lastname: Orriols
authors.forename: José-Román
authors.initials: JR
authors.lastname: Escudero
authors.forename: José
authors.initials: J
authors.lastname: Martínez-González
authors.forename: Luis
authors.initials: L
authors.lastname: Vila
mesh_terms: D000818:Animals; D015153:Blotting, Western; D015687:Cell Hypoxia / Q000235:genetics / Q000502:physiology*; D002478:Cells, Cultured; D017077:Culture Media, Conditioned / Q000494:pharmacology; D051546:Cyclooxygenase 2 / Q000378:metabolism; D015232:Dinoprostone / Q000378:metabolism; D042783:Endothelial Cells / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D011464:Epoprostenol / Q000378:metabolism*; D006801:Humans; D053583:Interleukin-1beta / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009131:Muscle, Smooth, Vascular / Q000166:cytology*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic / Q000235:genetics; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics / Q000378:metabolism*
chemical_list: D017077:Culture Media, Conditioned; D053583:Interleukin-1beta; D011464:Epoprostenol; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; D015232:Dinoprostone