title: Modulation of the cochaperone AHA1 regulates heat-shock protein 90 and endothelial NO synthase activation by vascular endothelial growth factor.
abstract: OBJECTIVE
  Vascular endothelial growth factor (VEGF) signaling to endothelial NO synthase (eNOS) plays a central role in angiogenesis. In endothelial cells (ECs), heat-shock protein 90 (Hsp90) is also a regulator of eNOS activity. Our study is designed to determine whether modulation of the activator of Hsp90 ATPase 1 (AHA1) regulates the function of Hsp90 in ECs.
  
  
  RESULTS
  We show that eNOS phosphorylation on Ser-1179 after VEGF stimulation is significantly reduced in ECs transfected with a small interfering RNA against AHA1. Accordingly, VEGF-stimulated NO production, endothelial permeability, cell migration, and EC invasion in Matrigel implants in mice are reduced in small interfering RNA against AHA1-treated conditions. Furthermore, the induction of eNOS association with Hsp90 after VEGF stimulation is decreased in AHA1-downregulated cells. We also demonstrate that modulation of Hsp90 activity by AHA1 regulates phosphorylation of Hsp90 on Tyr-300. Interestingly, the association of AHA1 with Hsp90 is increased after c-Src-mediated phosphorylation of Hsp90 on Tyr-300. Finally, we show that overexpression of AHA1 in ECs promotes association of eNOS and Hsp90, phosphorylation of Ser-1179 of eNOS, increases NO production, and cell migration.
  
  
  CONCLUSIONS
  These results reveal that modulation of Hsp90 activity by AHA1 regulates VEGF signaling to eNOS and angiogenesis.
authors.affiliation: IRCM, 110 des Pins Ave West, Montreal, QC, H2W 1R7 Canada.
authors.forename: Fanny
authors.initials: F
authors.lastname: Desjardins
authors.forename: Chantal
authors.initials: C
authors.lastname: Delisle
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Gratton
mesh_terms: D000818:Animals; D019556:COS Cells; D002417:Cattle; D002465:Cell Movement / Q000502:physiology; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D015536:Down-Regulation / Q000502:physiology; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D023421:Models, Animal; D018832:Molecular Chaperones / Q000378:metabolism*; D018919:Neovascularization, Physiologic / Q000502:physiology; D009569:Nitric Oxide / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D010766:Phosphorylation; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*
chemical_list: C515652:AHSA1 protein, human; D018841:HSP90 Heat-Shock Proteins; D018832:Molecular Chaperones; D042461:Vascular Endothelial Growth Factor A; D009569:Nitric Oxide; D052250:Nitric Oxide Synthase Type III