Sodium Salicylate Decreases Intracellular ATP, Induces Both Heat Shock Factor Binding and Chromosomal Puffing, but Does Not Induce hsp 70 Gene Transcription in Drosophila

doi:10.1074/jbc.271.43.26971

Sodium Salicylate Decreases Intracellular ATP, Induces Both Heat Shock Factor Binding and Chromosomal Puffing, but Does Not Induce hsp 70 Gene Transcription in *Drosophila**

From the Department of Zoology, Erindale College, University of Toronto, Mississauga, Ontario, Canada L5L 1C6

^§ To whom correspondence should be addressed:
Dept. of Zoology, Erindale College, University of Toronto, 3359 Mississauga Rd., Mississauga, Ontario, Canada L5L 1C6.
Tel.: 905-828-3894; Fax: 905-828-3792; E-mail: twestwoo{at}credit.erin.utoronto.ca

↵^‡ Current address: Div. of Cancer Research and Dept. of Medical Biophysics, Reichmann Research Bldg., Sunnybrook Health Science Centre, 275 Bayview Ave., North York, Ontario, Canada.

Abstract

Sodium salicylate has long been known to be an inducer of the heat shock puffs and presumably heat shock gene transcription in the polytene chromosomes of Drosophila salivary gland cells. Stress-induced transcription of the heat shock genes is mediated by the transcription factor known as Heat Shock Factor (HSF). In yeast, sodium salicylate has been reported to induce the DNA binding of HSF but not heat shock gene transcription itself, and similar findings have been reported in human cells. This apparent discrepancy in the induction of certain aspects of the heat shock response between these organisms prompted us to carefully reexamine the induction of the heat shock response in Drosophila salivary gland cells of third instar larvae and Drosophila tissue culture (SL2) cells. Sodium salicylate (3-30 mM) decreases intracellular ATP levels in SL2 cells and induces HSF binding activity in SL2 and salivary gland cells in a dose-dependent manner. Despite the induction of HSF binding and heat shock puffs in polytene chromosomes, we found no evidence for increased hsp 70 gene transcription suggesting that chromosomal puffing and gene transcription may be separable events. Salicylate did not induce the HSF hyperphosphorylation that is normally associated with HSF activation. Furthermore, salicylate (30 mM) prevented heat-induced hyperphosphorylation of HSF and hsp 70 gene transcription indicating that salicylate's inhibitory effect on hsp 70 transcription may be independent of its effect on HSF binding activity. We propose that the reduction in intracellular ATP caused by the addition of salicylate likely plays a role in the activation of HSF binding and the inhibition of both HSF hyperphosphorylation and hsp 70 gene transcription.

Footnotes

↵* This work was supported by a grant from the Medical Research Council of Canada. The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

HSF

heat shock factor

Bis-Tris

bis(2-hydroxyethyl)iminotris(hydroxymethyl)methane

EMSA

electrophoretic mobility shift assay

HSE

heat shock element

hsp

heat shock protein

SL2

Schneider line 2

TB1

transcription buffer 1

TBE

Tris-borate-EDTA

PAGE

polyacrylamide gel electrophoresis.
↵² N. A. Winegarden and J. T. Westwood, unpublished observations.
- Received February 21, 1996.
- Revision received August 6, 1996.