SUPPRESSION OF HEAT-INDUCED HSP70 EXPRESSION BY THE 70-KDA SUBUNIT OFTHE HUMAN KU AUTOANTIGEN

Expression of the 70-kDa polypeptide of human Ku autoantigen in rat ce lls is shown to suppress specifically the induction of hsp70 upon heat shock. Thermal induction of other heat shock proteins is not signific antly affected, nor is the state of phosphorylation or the DNA binding ability of the heat shock transcription factor HSF1. These findings s upport a model in which hsp70 gene expression is controlled by a secon d regulatory factor in addition to the positive activator HSF1. The Ku autoantigen, or a protein closely related to it, is likely to be invo lved in the regulation of hsp70 expression.