REGULATION OF CHEMICAL STRESS-INDUCED HSP70 GENE-EXPRESSION IN MURINE L929 CELLS

We have investigated the regulation mechanism of chemical stress-induced hsp70 gene expression in murine L929 cells. Our data show that chemical treatments including sodium arsenite, cadmium chloride and sodium salicylate, induced significant synthesis of hsp70 and its mRNA. The induced hsp70 gene expression appears to be regulated at the transcriptional level. A factor (CHBF), which constitutively binds to the heat shock element (HSE) at 37 degrees C, functions like a negative regulator and the heat-induced heat shock factor (HSF) acts as an activator. The chemical treatments that induce significant hsp70 synthesis activate HSF binding to HSE but also dissociate the HSE-CHBF complex. Some chemical treatments, e.g. IPTG, which fail to activate hsp70 gene transcription, still activate HSF binding to HSE. However, in this case, the HSE-CHBF complex remained like that of untreated control cells.