Differential Expression and Regulation of hsp70 and hsp90 by Phorbol Esters and Heat Shock

doi:10.1074/jbc.270.23.14094

Differential Expression and Regulation of hsp70 and hsp90 by Phorbol Esters and Heat Shock (*)

From the (1) Health and Environment Program, Nuclear Medicine Division and the
(2) Pulmonary Division, University Hospital, 1211 Geneva 14, Switzerland and the
(3) Laboratoire de Physiologie Respiratoire, CHU Cochin Port-Royal, 24, rue du Faubourg Saint-Jacques, 75014 Paris, France

^§ To whom correspondence should be addressed in Paris. Tel.: 33-1-44-41-23-36; Fax: 33-1-44-41-23-33.

Abstract

Human peripheral blood monocytes (PBM) produce superoxide anions (O) by a process involving electron transfer from NADPH to O², catalyzed by the respiratory burst enzyme NADPH oxidase. We have previously shown that phagocytosis, while activating NADPH oxidase, induced in PBM the synthesis of heat shock (HS) proteins (HSP). The present study was undertaken to establish whether this increase in HSP expression was related to O and/or to classical second messengers such as protein kinase C (PKC). Thus, the effects of the PKC activator phorbol 12-myristate 13-acetate (PMA) were compared with those of heat shock on the expression, in PBM, of the major HSP, hsp70 and hsp90, using biometabolic labeling, Western and Northern blotting, and gel mobility shift assays. PMA induced the accumulation of mRNA and an increased expression of hsp90 and, to a lesser extent, hsp/hsc70 (hsc is the cognate, constitutive form). This induction was also observed in PBM from patients with chronic granulomatous disease, a genetic defect in NADPH oxidase, and was abolished by the PKC inhibitors staurosporine and H-7. PMA did not cause activation of the HS factor, and the PMA-induced overexpression of HSP was not blocked by the transcriptional inhibitor actinomycin D. HSP-specific mRNA stability was increased after PMA exposure as compared with heat shock. These results suggest that O is not involved in the PMA-mediated induction of hsp70 and hsp90 and that, in contrast to HS, PMA increases the expression of HSP as a result of PKC-induced mRNA stabilization rather than of transcriptional activation of HS genes.

Footnotes

↵* This work was supported by Swiss National Research Foundation Grants 32-37464.93 (to B. S. P.) and 31-37799.93 (to L. J.) and by INSERM, France (to M. R. J. S. and B. S. P.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

HS

heat shock

HSP

heat shock protein(s)

PMA

phorbol 12-myristate 13-acetate

PKC

protein kinase C

PBM

peripheral blood monocytes

CGD

chronic granulomatous disease

NBT

nitro blue tetrazolium

PAGE

polyacrylamide gel electrophoresis

HSE

heat shock element

HSF

heat shock factor.