title: Prolyl hydroxylase 2 deficiency limits proliferation of vascular smooth muscle cells by hypoxia-inducible factor-1{alpha}-dependent mechanisms.
abstract: Arterial O(2) levels are thought to modulate vascular smooth muscle cell (VSMC) proliferation and vascular remodeling, but the mechanisms involved are poorly understood. Here, we tested the hypothesis that PHD2, a prolyl hydroxylase domain (PHD)-containing O(2) sensor, modulates growth factor-induced proliferative responses of human pulmonary artery SMC (HPASMC). We found that both PHD1 and PHD2 were robustly expressed by HPASMC, and inhibiting prolyl hydroxylase activity pharmacologically by using the nonselective dioxygenase inhibitor dimethyloxalylglycine (DMOG) inhibited proliferation and cyclin A expression induced by PDGF-AB or FGF-2. Specific knockdown of PHD2 using small interfering RNAs had similar effects. The inhibitory effects of DMOG and PHD2 knockdown on proliferation and cyclin A expression were seen under both normoxic (20% O(2)) and moderately hypoxic (5% O(2)) conditions, and PHD2 expression was not affected by O(2) level nor by stimulation with PDGF or FGF-2, indicating that the proproliferative influence of PHD2 does not involve alterations of its expression. Knockdown of PHD2 increased hypoxia-inducible factor (HIF)-1alpha expression, as expected, but we also found that HIF-1alpha knockdown abolished the inhibitory effect of PHD2 knockdown on PDGF-induced cyclin A expression. Therefore, we conclude that PHD2 promotes growth factor-induced responses of human VSMC, acting by HIF-1alpha-dependent mechanisms. Given the role of PHD2 as an oxygen sensor in mammalian cells, these results raise the possibility that PHD2 links VSMC proliferation to O(2) availability.
authors.affiliation: Molecular Cardiology Research Institute, Department of Medicine, Tufts Medical Center, Boston, Massachusetts, USA.
authors.forename: Kelly
authors.initials: K
authors.lastname: Schultz
authors.forename: Vanishree
authors.initials: V
authors.lastname: Murthy
authors.forename: Jeffrey B
authors.initials: JB
authors.lastname: Tatro
authors.forename: Debbie
authors.initials: D
authors.lastname: Beasley
mesh_terms: D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D019925:Cyclin A / Q000378:metabolism; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D000860:Hypoxia / Q000378:metabolism* / Q000503:physiopathology; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism*; D064799:Hypoxia-Inducible Factor-Proline Dioxygenases; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism / Q000494:pharmacology; D010982:Platelet-Derived Growth Factor / Q000378:metabolism / Q000494:pharmacology; D011393:Procollagen-Proline Dioxygenase / Q000235:genetics / Q000378:metabolism*; D011651:Pulmonary Artery / Q000166:cytology*; D034741:RNA, Small Interfering
chemical_list: D019925:Cyclin A; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D010982:Platelet-Derived Growth Factor; D034741:RNA, Small Interfering; D016222:Fibroblast Growth Factor 2; C490190:EGLN1 protein, human; D011393:Procollagen-Proline Dioxygenase; D064799:Hypoxia-Inducible Factor-Proline Dioxygenases; D010100:Oxygen