Characterization of HSE sequences in human Hsp40 gene: structural and promoter analysis

We have recently cloned a gene of Hsp40, a human homologue of bacterial DnaJ. Here we describe the structural and promoter analysis of human Hsp40 gene. Analysis of Hsp40 transcripts by 5' and 3' RACE suggested that they have different 3' ends, and primer extension studies revealed that the major transcription initiation site was localized 47 bp upstream of the ATG translation initiation codon. Promoter analysis using deletion derivatives defined a minimal region which was active in response to heat shock. The region contained the consensus heat shock element (HSE) sequences. The factor bound to these sequences was suggested to be a heat shock factor 1 (HSF1) by gel mobility supershift assay. In vivo footprinting and promoter analysis revealed that the HSEs in 5' upstream region of human Hsp40 gene were composed of eight contiguous (A/G)GAAN motifs and were essential for heat shock response. These results indicate that Hsp40 is a real heat shock protein. It is also shown that the HSE found in the first intron might not be the essential element for heat shock response.