Modulation of the Cochaperone Activator of Heat-Shock Protein 90 ATPase 1 in Endothelial Cells Regulates Heat-Shock Protein 90 and Endothelial NO Synthase Activation by Vascular Endothelial Growth Factor
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.
Methods and Results—We show that eNOS phosphorylation on Ser-1179 after VEGF stimulation is significantly reduced in ECs transfected with an 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.
Conclusion—These results reveal that modulation of Hsp90 activity by AHA1 regulates VEGF signaling to eNOS and angiogenesis.
- activator of heat-shock protein 90 ATPase 1
- endothelial NO synthase
- heat-shock protein 90
- vascular endothelial growth factor
- Received February 24, 2012.
- Accepted July 17, 2012.
- © 2012 American Heart Association, Inc.