In response to increase in ambient temperature or other noxious stimuli, all organisms generally respond by a rapid synthesis of heat shock RNA's and proteins. The regulation of heat shock gene transcription occurs by a heat shock factor (HSF) which binds to heat shock elements (HSEs) in the gene. Even though HSEs are highly conserved among the species, there appear to be marked difference in HSFs. Two forms of HSFs have been recently cloned from human B cell lymphoma and HeLa cells. Last year we used both reverse - transcriptase polymerase chain reaction (RT - PCR) and standard cloning techniques to clone an HSF gene from human retinal cDNA library. Northern blot analysis of poly A+ RNA isolated from human retina indicated the presence of RNA of 2.4 kb size hybridizing with human [32P] HSF probe. The same probe was used to identify a number of cDNA clones of HSF in the human retinal library. Two of these clones were subcloned for sequence analysis. The insert size of both clones were found to be l.2 Kb. Sequencing of both the inserts yielded a complete sequence of human HSF1. The existence and expression of a HSF gene in human retina underscores the possibility of induction of heat shock factor(s) by change in ambient temperature or by noxious stimuli as a means of protection of the retina from injury such as high temperature or oxidative damage.
