Evidence of multi-step regulation of HSP72 expression in experimental sepsis

Heat shock proteins (Hsps) are a family of highly conserved proteins induced in response to various stresses. Hsps protect cells against subsequent lethal circumstances. Previous work from our laboratory has indicated that Hsp72 is not induced during experimental sepsis in rats, but the regulation of the induction of Hsp72 synthesis in this disease cascade has not been investigated. In the present study, we evaluated the expression of the hsp72gene, focusing on the activation and DNA-binding ability of heat shock factor 1 (HSF1), hsp mRNA accumulation, and Hsp72 synthesis in animal sepsis models induced by cecal ligation and puncture procedure. The results were compared with those of sham-treated and heat-shocked rats. It was shown that the expression of the hsp72 gene in sepsis was a multi-step process, as previously documented in in vitro studies. Hsp72 synthesis was not induced during sepsis, whereas DNA binding of HSF was detectable, suggesting that the induction of Hsp72 is blocked downstream to HSF-DNA complex formation by the metabolic alteration occurring during sepsis. The dissociation failure of the constitutive heat shock element binding factor (CHBF) from the heat shock element may play an important role in this negative regulation.