HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 283, Issue 43, 29069-29076, October 24, 2008

This Article Full Text Full Text (PDF) All Versions of this Article: 283/43/29069    most recent M803638200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Averna, M. Articles by Melloni, E. Search for Related Content PubMed PubMed Citation Articles by Averna, M. Articles by Melloni, E. Social Bookmarking                      What's this?

Functional Role of HSP90 Complexes with Endothelial Nitric-oxide Synthase (eNOS) and Calpain on Nitric Oxide Generation in Endothelial Cells^*

From the Department of Experimental Medicine (DIMES), Biochemistry Section, and Centre of Excellence for Biomedical Research (CEBR), University of Genoa, Viale Benedetto XV, 1-16132 Genoa, Italy

Although several reports have indicated that eNOS is a highly sensitive calpain substrate, the occurrence of a concomitant Ca²⁺-dependent activation of the synthase and of the protease has never been analyzed in specific direct experiments. In this study, we have explored in vivo how eNOS can undergo Ca²⁺-dependent translocation and activation, protected against degradation by activated calpain. Here we demonstrate that following a brief exposure to Ca²⁺-loading, the cytosolic eNOS-HSP90 complex recruits calpain in a form in which the chaperone and the synthase are almost completely resistant to digestion by the protease. Furthermore, in the presence of the HSP90 inhibitor geldanamycin, a significant decrease in NO production and an extensive degradation of eNOS protein occurs, indicating that dissociation from membranes and association with the chaperone is correlated to the protection of the synthase. Experiments with isolated membrane preparations confirm the primary role of HSP90 in dissociation of eNOS from caveolae. Prolonged exposure of cells to Ca²⁺-loading resulted in an extensive degradation of both eNOS and HSP90, accompanied by a large suppression of NO production. We propose that the protective effect exerted by HSP90 on eNOS degradation mediated by calpain represents a novel and critical mechanism that assures the reversibility of the intracellular trafficking and activation of the synthase.

Received for publication, May 12, 2008 , and in revised form, July 23, 2008.

^* This work was supported in part by grants from MIUR, FIRB, and PRIN projects, and from the University of Genoa. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

¹ To whom correspondence should be addressed: DIMES-Biochemistry Section, Viale Benedetto XV, 1-16132 Genoa. Tel.: 39-010-3538128; Fax: 39-010-518343; E-mail: melloni{at}unige.it.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?