Cyclic AMP response element binding protein (CREB) participates in the heat-inducible expression of humanhsp90β gene

Human heat shock protein 90b gene ( hsp90b ) is a constitutively expressed heat shock gene existing in most of cell types tested that can be further induced by heat shock. Chloramphenical acetyl transferase (CAT) reporter plasmids driven by different regulatory fragments of hsp90b gene were constructed and transfected into Jurkat cells to explore the role of a cAMP response element (CRE) in the upstream of the gene. Results show that, in comparison with the wild type construct, a severe reduction (~2/3) in the increased folds of promoter activity induced by heat shock at 42℃ for 1 h was observed in a construct with CRE-containing fragment (-173/-91bp) deleted. Electrophoretic mobility shift assays (EMSA) showed that phosphorylated CRE-binding protein (CREB) in the nuclear extract of heat shocked Jurkat cells is specifically bound to the fragment. Additionally, both of the phosphorylation on CREB and the activity of protein kinase A (PKA) were found in Jurkat cells to be enhanced with extending time of heat shock treatment. Our results indicate that in addition to the intronic HSE/HSF pathway, phosphorylated CREB also participates in the heat shock induced expression of human hsp90b gene via its interaction with CRE which may be regulated by PKA-sig- naling pathway.