During ischemia-reperfusion in rat kidneys, heat shock response is not regulated by expressional changes of heat...

Ischemia-reperfusion injury is known to induce the inducible form of the 70 kDa heat shock protein HSP70i (or HSP72) mainly via rapid activation of heat shock transcription factor 1 (HSF1). However, little is known about the regulation of the HSF1 gene. We therefore studied the time course of HSF1 mRNA transcription and its relation to the expression pattern of the HSP70i mRNA in the renal cortex, this being the most vulnerable and functionally most important part of the kidney, after different periods of unilateral renal ischemia (10-180 min) and reperfusion (up to 60 min) in male Wistar rats (10 weeks old). Immediately after ischemia there was a significant induction of HSP70i genes. While HSP70i expression constantly increased (up to 4-fold) during reperfusion, even to a higher extent with prolongation of ischemia, HSF1 mRNA remained constitutively expressed under all conditions. Thus, we conclude that during ischemia-reperfusion in rat kidneys, the heat shock response is regulated by other means than expressional changes of HSF1.