title: Role of heat shock protein 90 in bradykinin-stimulated endothelial nitric oxide release.
abstract: Previously we described ENAP-1, a 90-kDa protein that is tyrosine-phosphorylated in endothelial cells in response to bradykinin (BK) stimulation and is associated with endothelial nitric oxide synthase (eNOS). Subsequently, other investigators demonstrated that eNOS interacts with heat shock protein 90 (Hsp90) following stimulation of endothelial cells with vascular endothelial growth factor (VEGF), histamine, or fluid shear stress. Therefore, we tested the hypotheses that ENAP-1 and Hsp90 are the same protein and that BK activation of eNOS is dependent on Hsp90. Immunoblotting of immunoprecipitated Hsp90 with anti-phosphotyrosine antibody shows that Hsp90 is tyrosine-phosphorylated in response to BK stimulation of bovine aortic endothelial cells (BAECs). Coimmunoprecipitation of Hsp90 with anti-eNOS antibody reveals a Hsp90-eNOS complex in endothelial cells under basal conditions that is increased following BK stimulation. Taken together with the tyrosine phosphorylation data, these data suggest that ENAP-1 is Hsp90. BK-stimulated nitric oxide (NO) release is completely blocked by pretreatment with geldanamycin, a specific inhibitor of Hsp90, illustrating the importance of the Hsp90-eNOS interaction. In vitro binding assays with Hsp90-glutathione-S-transferase fusion proteins show direct binding of eNOS with the middle domain (residues 259-615) of Hsp90.
authors.affiliation: Vascular Biology Center, Medical College of Georgia, Augusta, GA 30912-2500, USA.
authors.forename: M B
authors.initials: MB
authors.lastname: Harris
authors.forename: H
authors.initials: H
authors.lastname: Ju
authors.forename: V J
authors.initials: VJ
authors.lastname: Venema
authors.forename: M
authors.initials: M
authors.lastname: Blackstone
authors.forename: R C
authors.initials: RC
authors.lastname: Venema
mesh_terms: D000818:Animals; D001011:Aorta / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D016227:Benzoquinones; D001920:Bradykinin / Q000494:pharmacology*; D002417:Cattle; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000378:metabolism / Q000502:physiology*; D004791:Enzyme Inhibitors; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D007313:Insecta; D047029:Lactams, Macrocyclic; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011809:Quinones / Q000494:pharmacology
chemical_list: D016227:Benzoquinones; D004791:Enzyme Inhibitors; D018841:HSP90 Heat-Shock Proteins; D047029:Lactams, Macrocyclic; D011809:Quinones; D009569:Nitric Oxide; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; D001920:Bradykinin; C001277:geldanamycin