INVOLVEMENT OF HEAT-SHOCK ELEMENTS AND BASAL TRANSCRIPTION ELEMENTS IN THE DIFFERENTIAL INDUCTION OF THE 70-KDA HEAT-SHOCK-PROTEIN AND ITS COGNATE BY CADMIUM CHLORIDE IN 9L RAT-BRAIN TUMOR-CELLS

Exposure of 9L rat brain tumor cells to 40-100 mu M CdCl2 for 2 h lead s to an induction of a wide spectrum of heat shock proteins (HSPs). We have demonstrated that induction of the 70-kDa HSP (HSP70) and enhanc ed expression of its cognate (HSC70) by cadmium are concentration depe ndent and that the induction kinetics of these HSP70s are different.. The increased synthesis of the HSP70s is accompanied by the increase i n hsp70 and hsc70 mRNA levels, indicative of transcriptional regulatio n of the heat shock genes. Electrophoretic mobility shift assay (EMSA) using probes encompassing heat shock element (HSE), TATA, CC, and CCA AT boxes derived from the promoter regions of the heat shock genes sho ws distinguished binding patterns between hsp70 and hsc70 genes in bot h control and cadmium-treated cells. The results indicate that, in add ition to the HSEs, the basal transcription elements are important in t he regulation of the heat shock genes. The binding patterns of the cor responding transcription factors of these elements are examined by EMS A by using extended promoter fragments from respective heat shock gene s with sequential addition of excess oligonucleotides encompassing ind ividual transcription elements. Taken together, our results show that the differential induction of hsp70 and hsc70 involves multiple transc ription factors that interact with HSE, TATA, GC, and CCAAT boxes. (C) 1998 Wiley-Liss. Inc.