Isolation of chicken hsp90 beta gene promoter

In order to define the mechanisms responsible for the differential expression of chicken hsp90 alpha and beta genes, a portion of the chicken hsp90 beta genomic sequence, including 3081 bp upstream from the transcription initiation site and 2718 bp of structural gene sequence which covers 7 exons and 6 introns was investigated. The transcriptional initiation site was determined by primer extension, RNAase and S1 nuclease mapping, Northern blot and cloning of 5' end of cDNA. The first intron, as in other hsp90 genes, is located just before the ATG initiation codon. Three Sp1 sites are located near the TATA box. The apparent major divergence with the hsp90 alpha promoter is that, in the hsp90 beta promoter, the only CAAT box and HSE element are located at about 3 and 2 kb upstream the TATA box, respectively. These features may explain why chicken hsp90 beta mRNA is generally less abundant than alpha and is not inducible by heat shock or serum/growth factor stimulation.