Interaction Between HSP70 And P53 In The Yeast Two-hybrid System And Its Influences On The Subcellular Localizations Of P53

As a kind of molecular chaperon, HSPs take important parts in protein folding, assembling and transportation in normal conditions, and protecting cells from the deleterious effects of stress. They are indispensable for the survival of cells. Moreover, HSPs have been found to be correlated with the occurrence and development of the tumors. High expressions of HSP70 were detected in many tumors and anti-sense HSP70 transfection may induce apoptosis in the tumors. The expression of HSP70 was regulated by cell cycle in normal cells, and induced by the aberrant proteins in tumor cells.During the complex course of the occurrence and development of the tumors, the cooperation of oncogene and tumor suppress gene play significant roles in the proliferation and transformation of cells. Point mutations in the P53 gene are detected in >50% of the most common tumors. HSPs may form complex with various oncoproteins, such as Raf, v-Src, Rb, P53 etc, mediating their conformational maturation and transportation that are involved in the transformation of cells. It was reported that the combination of HSP70-P53contributed a lot to the regulation of P53. And the HSP70-P53 complex have been detected in both breast cancer and oral cancer.Hepatocellular carcinoma (HCC) is one of the malignant tumors with high incidence in China. The mechanism and significance of HSPs in HCC are unclear. In our previous studies, we have detected high expressions of HSPs in HCC, and part of HSP70 and P53 are colocalized in nuclei, We have already proved their combination by co-immunoprecipitation.In order to further verify the relationship of HSP70 and P53, and then find out the accurate interacting sites of each other, we examined the interaction of HSP70-P53 by yeast two-hybrid system in this study. The activation of His reporter gene was detected while that of Ade was not. Then we separately and simultaneously transfected the pDsRedl-Cl-hsp70 and pEGFP-C3-P53 into COS7 cells. The transfection results showed that wild and mutant type P53 had different subcellular localizations, indicating that the subcellular localizations of P53 have closely related to its functions; hi co-transfected cells, wild type P53 proteins transfer from the nucleus to the cytoplasm; and HSP70 have co-localization with mutant P53 (273) in the cytoplasm; but not with mutant P53 (342-stop) of which C-terminal is a mutant deletion. These results indicated that there were interactions between HSP70 and P53 affecting the subcellular localizations of P53, among which the C-terminal of P53 might play an important role.