Hsp90 Genes In Signal Transduction And Regulatory Mechanisms

In order to study the effect of Rac-MEKK-JNK signal pathway on heat shock-induced hsp90 gene expression and the impact of Hsp90 on the regulation of the pathway, DN-Rac, DN-MEKK or DN-JNK were cotransfected with hsp90al or hsp90p3.1 CAT reporter plasmid into Jurkat or LETPa-2 cells individually, the CAT mRNA expression was then determined quantitatively by competitive RT-PCR based system. Western blot was carried out to detect the expression level and phosphorylation of c-Jun in Jurkat and LETPa-2 cells that were transfected with DN-Rac, DN-MEKK or DN-JNK. By in vitro kinase activity assay and Western blot the effect of galdnamycin (GA) on heat induced JNK activity were evaluated. We get the results that in both Jurkat and LETPa2 cells transfected with DN-Rac, DN-MEKK or DN-JNK, heat shock induced relative α1 and β3.1 CAT mRNA expression level were decreased. C-Jun expression and phosphorylation were also inhibited by the transfection of either one of DN-Rac, DN-MEKK or DN-JNK. With GA treatment, heat shock induced JNK activity was repressed, while the expression level of JNK or c-Jun was not obviously changed. We concluded that Rac-MEKK-JNK pathway promotes heat shock induced hsp90α and hsp90β gene expression and hsp90 might participate in the regulation of heat shock activated Rac-MEKK-JNK signal pathway in both Jurkat and LETPa-2 cells.In order to study the effect of heat shock on NF-κB activation in Jurkat and LETPa2 cells, We used Western blot to detect the NF-κB in the nucleaus and IκBα expression and phosphorylation after heat shock. The results show that heat shock could inhibit NF-κB entering into the nucleaus. Heat shock could also inhibit the IκBα phosphorylation but promote IκBα expression. In vitro kinase assay shows that heat shock inhibit the constitutive IKK activity in both cells. These results suggested that NF-κB is constitutively activated in Jurkat and LETPa2 cells. Heat shock might inhibit NF-κB activation by decreasing the IκBα expression and IKK activity.To investigate the mechanisms of STAT1 and STAT3 on the transcriptional...