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Inhibition of heat shock protein 90 (hsp90) in proliferating endothelial cells uncouples endothelial nitric oxide synthase activity. Free Radic Biol Med 2003 Jan 15;34(2):269-76



Pubmed ID




Scopus ID

2-s2.0-0037438835   53 Citations


Dual increases in nitric oxide ((*)NO) and superoxide anion (O(2)(*-)) production are one of the hallmarks of endothelial cell proliferation. Increased expression of endothelial nitric oxide synthase (eNOS) has been shown to play an important role in maintaining high levels of (*)NO generation to offset the increase in O(2)(*-) that occurs during proliferation. Although recent reports indicate that heat shock protein 90 (hsp90) associates with eNOS to increase (*)NO generation, the role of hsp90 association with eNOS during endothelial cell proliferation remains unknown. In this report, we examine the effects of endothelial cell proliferation on eNOS expression, hsp90 association with eNOS, and the mechanisms governing eNOS generation of (*)NO and O(2)(*-). Western analysis revealed that endothelial cells not only increased eNOS expression during proliferation but also hsp90 interactions with the enzyme. Pretreatment of cultures with radicicol (RAD, 20 microM), a specific inhibitor that does not redox cycle, decreased A23187-stimulated (*)NO production and increased L(omega)-nitroargininemethylester (L-NAME)-inhibitable O(2)(*-) generation. In contrast, A23187 stimulation of controls in the presence of L-NAME increased O(2)(*-) generation, confirming that during proliferation eNOS generates (*)NO. Our findings demonstrate that hsp90 plays an important role in maintaining (*)NO generation during proliferation. Inhibition of hsp90 in vascular endothelium provides a convenient mechanism for uncoupling eNOS activity to inhibit (*)NO production. This study provides new understanding of the mechanisms by which ansamycin antibiotics inhibit endothelial cell proliferation. Such information may be useful in the development and design of new antineoplastic agents in the future.

Author List

Ou J, Ou Z, Ackerman AW, Oldham KT, Pritchard KA Jr


Keith T. Oldham MD Professor in the Surgery department at Medical College of Wisconsin
Kirkwood A. Pritchard PhD Professor in the Surgery department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Blotting, Western
Cell Division
Cells, Cultured
Enzyme Inhibitors
HSP90 Heat-Shock Proteins
NG-Nitroarginine Methyl Ester
Nitric Oxide
Nitric Oxide Synthase
jenkins-FCD Prod-482 91ad8a360b6da540234915ea01ff80e38bfdb40a