Heat shock stimulation of a tilapia heat shock protein 70 promoter is mediated by a distal element

We reported previously that a tilapia (Oreochromis mossambicus) heat shock protein 70 (HSP70) promoter is able to confer heat shock response on a repo rter gene after transient expression both in cell culture and in microinjec ted zebrafish embryos. Here we present the first functional analysis of a f ish HSP70 promoter, the tiHSP70 promoter. Using transient expression experi ments in carp EPC (epithelioma papulosum cyprini) cells and in microinjecte d zebrafish embryos, we show that a distal heat shock response element (HSE 1) at approx. -800 is predominantly responsible for the heat shock response of the tiHSP70 promoter. This element specifically binds an inducible tran scription factor, most probably heat shock factor, and a constitutive facto r. The constitutive complex is not observed with the non-functional, proxim al HSE3 sequence, suggesting that both factors are required for the heat sh ock response mediated by HSE1.