1. Department of Pharmacology and Molecular Cardiobiology Program,
2. Department of Medicine, Boyer Center for Molecular Medicine, Yale University School of Medicine, New Haven, Connecticut 06536, USA
3. Dipartimento di Farmacologia Sperimentale, Universita' degli Studi di Napoli Federico II, 80131 Napoli, Italy
4. Present address: Harvard Medical School, Vascular Research Division, Brigham and Women's Hospital, 221 Longwood Avenue, LMRC-406, Boston, Massachusetts 02115, USA.

Correspondence to: William C. Sessa¹ Correspondence and requests for materials should be addressed to W.C.S. (e-mail: Email: william.sessa@yale.edu).

Abstract

Heat-shock protein 90 (Hsp90) coordinates the trafficking and regulation of diverse signalling proteins, but its precise role in regulating specific cellular targets is not known¹,². Here we show that Hsp90 associates with endothelial nitric oxide synthase (eNOS) and is rapidly recruited to the eNOS complex by agonists that stimulate production of nitric oxide, namely vascular endothelial growth factor, histamine and fluid shear stress. Moreover, the binding of Hsp90 to eNOS enhances the activation of eNOS. Inhibition of signalling through Hsp90 attenuates both agonist-stimulated production of nitric oxide and endothelium-dependent relaxation of isolated blood vessels. Our results indicate that Hsp90 facilitates signalling mediated by growth-factor, G-protein and mechanotransduction pathways that lead to the activation of eNOS. These observations indicate that in addition to its role as a molecular chaperone involved in protein folding and maturation, Hsp90 may also be recruited to cellular targets depending on the activation state of the cell.