Heat Shock Protein 90 Mediates the Balance of Nitric Oxide and Superoxide Anion from Endothelial Nitric-oxide Synthase

Kirkwood A. Pritchard, Allan W. Ackerman, Eric R. Gross, David W Stepp, Yang Shi, Jason T. Fontana, John E. Baker, William C. Sessa

Research output: Contribution to journalArticlepeer-review

274 Scopus citations

Abstract

The balance of nitric oxide (·NO) and superoxide anion (O 2.- plays an important role in vascular biology. The association of heat shock protein 90 (Hsp90) with endothelial nitric-oxide synthase (eNOS) is a critical step in the mechanisms by which eNOS generates ·NO As eNOS is capable of generating both ·NO and O 2.- we hypothesized that Hsp90 might also mediate eNOS-dependent O2.- production. To test this hypothesis, bovine coronary endothelial cells (BCEC) were pretreated with geldanamycin (GA, 10 μg/ml; 17.8 μM) and then stimulated with the calcium ionophore, A23187 (5 μM). GA significantly decreased A23187-stimulated eNOS-dependent nitrite production (p < 0.001, n = 4) and significantly increased A23187-stimulated eNOS-dependent O2.- production (p < 0.001, n = 8). A23187 increased phospho-eNOS(Ser-1179) levels by >1.6-fold over vehicle (V)-treated levels. Pretreatment with GA by itself or with A23187 increased phospho-eNOS levels. In unstimulated V-treated BCEC cultures low amounts of Hsp90 were found to associate with eNOS. Pretreatment with GA and/or A23187 increased the association of Hsp90 with eNOS. These data show that Hsp90 is essential for eNOS-dependent ·NO production and that inhibition of ATP-dependent conformational changes in Hsp90 uncouples eNOS activity and increases eNOS-dependent O2.- production.

Original languageEnglish (US)
Pages (from-to)17621-17624
Number of pages4
JournalJournal of Biological Chemistry
Volume276
Issue number21
DOIs
StatePublished - Jan 25 2001
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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