Dissociation of cytosolic HSF1:HSP90 complex

Stable Identifier
R-HSA-3371586
Type
Reaction [dissociation]
Species
Homo sapiens
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In the absence of stress HSF1 is predominantly monomeric and is thought to be repressed in its inactive monomeric state by the following mechanisms:

  • interaction with chaperone proteins such as HSP90 (Zou J et al.1998; Guo Y et al. 2001)
  • intramolecular coiled-coil interactions between a hydrophobic leucine zipper domain in the carboxyl-terminus of the protein and three amino-terminal leucine zippers, which are required for homotrimerization and transcriptional activation (Rabindran SK et al. 1993; Zuo J et al. 1995)
  • post-translation modifications that include protein acetylation, sumoylation and phosphorylation may also contribute to HSF1 repression (Knauf U et al. 1996; Hietakangas V et al. 2003; Batista-Nascimento L et al. 2011)
The accumulation of misfolded proteins upon proteotoxic stresses leads to the release of HSF1 from the HSP90-containing multichaperone complex and results in HSF1 self-association to form homotrimers (Baler R et al. 1993). There is also evidence showing that HDAC6 senses the accumulation of misfolded, ubiquitinated protein aggregates in cells and induces dissociation of a repressive HDAC6:HSF1:HSP90 complex and subsequent HSF1 activation (Boyault C et al. 2007).

Literature References
PubMed ID Title Journal Year
9727490 Repression of heat shock transcription factor HSF1 activation by HSP90 (HSP90 complex) that forms a stress-sensitive complex with HSF1

Zou, J, Guo, Y, Guettouche, T, Smith, DF, Voellmy, R

Cell 1998
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