Activation of heat shock gene transcription by heat shock factor 1 involves oligomerization, acquisition of DNA-binding activity, and nuclear localization and can occur in the absence of stress

Kevin D. Sarge, Shawn P. Murphy, Richard I. Morimoto*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

710 Scopus citations

Abstract

The existence of multiple heat shock factor (HSF) genes in higher eukaryotes has prompted questions regarding the functions of these HSF family members, especially with respect to the stress response. To address these questions, we have used polyclonal antisera raised against mouse HSF1 and HSF2 to examine the biochemical, physical, and functional properties of these two factors in unstressed and heat-shocked mouse and human cells. We have identified HSF1 as the mediator of stress-induced heat shock gene transcription. HSF1 displays stress-induced DNA-binding activity, oligomerization, and nuclear localization, while HSF2 does not. Also, HSF1 undergoes phosphorylation in cells exposed to heat or cadmium sulfate but not in cells treated with the amino acid analog L-azetidine-2-carboxylic acid, indicating that phosphorylation of HSF1 is not essential for its activation. Interestingly, HSF1 and HSF2 overexpressed in transfected 3T3 cells both display constitutive DNA-binding activity, oligomerization, and transcriptional activity. These results demonstrate that HSF1 can be activated in the absence of physiological stress and also provide support for a model of regulation of HSF1 and HSF2 activity by a titratable negative regulatory factor.

Original languageEnglish (US)
Pages (from-to)1392-1407
Number of pages16
JournalMolecular and cellular biology
Volume13
Issue number3
DOIs
StatePublished - Mar 1993

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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