DOMINANT ROLE OF THE 2ND HEAT-SHOCK ELEMENT IN EXPRESSION OF THE HSP70-1 GENE IN RAT-LIVER AFTER WHOLE-BODY HYPERTHERMIA

We investigated the regulatory expression of the HSP70-1. gene in rat liver after whole body hyperthermia (rectal temperature of 42 degrees C for 30 min), After heat treatment, HSP70-1 mRNA showed a peak at 1 h, and its protein product began to increase at 3 h, Under these conditions, we identified cis-acting elements involved in the regulatory expression of the HSP70-1 gene by in vivo genomic footprinting, We observed that the second heat shock element (HSE-2; -201 to -178) was clearly protected from methylation by dimethyl sulfate in parallel with the increase in HSP70-1 mRNA, On the contrary, the most proximal HSE-1 (-120 to -101) was protected only slightly, Furthermore, the flanking regions of HSE-2, that is, an NF-kappa B-like element on the upstream side and a GC box on the downstream side were also protected simultaneously in accordance with the induced expression of the HSP70-1 gene, Gel mobility shift assays with nuclear extracts from rat liver at 30 min after heat treatment showed maximal DNA binding activity equally with oligonucleotides containing HSE-1 and HSE-S, respectively, and also demonstrated the participation of heat shock factor-1 (HSF1) in both cases, These results suggest that, in addition to HSF1, other regulatory factors might be involved in the dominant protection of HSE-2 in the promoter of the HSP70-1 gene in rat liver after whole body hyperthermia.