The DNA-binding activity of the human heat shock transcription factor is regulated in vivo by hsp70.
AUTOR(ES)
Mosser, D D
RESUMO
The human heat shock transcription factor (HSF) is maintained in an inactive non-DNA-binding form under nonstress conditions and acquires the ability to bind specifically to the heat shock promoter element in response to elevated temperatures or other conditions that disrupt protein structure. Here we show that constitutive overexpression of the major inducible heat shock protein, hsp70, in transfected human cells reduces the extent of HSF activation after a heat stress. HSF activation was inhibited more strongly in clones that express higher levels of hsp70. These results demonstrate that HSF activity is negatively regulated in vivo by hsp70 and suggest that the cell might sense elevated temperature as a decreased availability of hsp70. HSF activation in response to treatment with sodium arsenite or the proline analog azetidine was also depressed in hsp70-expressing cells relative to that in the nontransfected control cells. As well, the level of activated HSF decreased more rapidly in the hsp70-expressing clones when the cells were heat shocked and returned to 37 degrees C. These results suggest that hsp70 could play an active role in the conversion of HSF back to a conformation that does not bind the heat shock promoter element during the attenuation of the heat shock response.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=360250Documentos Relacionados
- Interaction between heat shock factor and hsp70 is insufficient to suppress induction of DNA-binding activity in vivo.
- The wing in yeast heat shock transcription factor (HSF) DNA-binding domain is required for full activity
- Heat shock-induced interactions of heat shock transcription factor and the human hsp70 promoter examined by in vivo footprinting.
- Progesterone enhances target gene transcription by receptor free of heat shock proteins hsp90, hsp56, and hsp70.
- The loop domain of heat shock transcription factor 1 dictates DNA-binding specificity and responses to heat stress