Hsp90�� Gene Expression Regulation Mechanism In Jurkat Cells

Human hsp90 genes are usually constitutively expressed in most mammalian cell types and can be further induced by heat shock and mitogen. This suggests that HSP90 proteins are critical to the cells' normal growth. In fact, as a specific molecular chaperone, HSP90 proteins are possibly involved in many important physiological processes such as signal transduction, cell cycle regulation and hormone response. So it is very meanful for us to study the regulatory mechanisms of expression of human hsp90 genes. Here, we first present the evidence of the role of CRE, AP-1 site and their own related transactivators in the regulation of human hsp90p gene; then we identify the DNase I hypersensitive sites in human hsp90p gene in Jurkat cells.— The role of CRE, AP-1 site and the related trans-activators in the expression of human hsp90p gene1. We first constructed the CAT and Luc reporter plasmid deleting CRE or AP-1 site or both. These deleting mutants were then transfected into Jurkat cells and the reporter activities were detected. The results show that CRE together with AP-1 site are critical for the high constitutive expression of human hsp90p gene; CRE and AP-1 site also participate in heat inducible expression of human hsp90p gene. We also found that the full-length promoter, only CRE deleted or only AP-1 site deleted mutants presented inducible reporter gene activity after PHA treatment; however, deletion mutant lacking both CRE and AP-1 site showed no inducible reporter gene activity after PHA treatment. These results indicate that CRE and AP-1 site mediate the PHA activated expression of human hsp90p gene.2. We then analyzed the roles of CRE related transactivators in the expression of hsp90p gene. By EMSA, we found that heat shock nuclear extracts and the labeled probe of -173/-91 fragment containing CRE can form three bands. The addition of the unlabeled wide type probe can efficiently compete three specific bands while the...