HPV-16E6 can induce multiple site phosphorylation of p53

Modulation of the activity of tumor suppressor p53 is a key event in the replication of many viruses. They could manipulate p53 function through modification of phosphorylation for their own purpose. However, there are scarce data on the relationship between high risk human papillomavirus (HPV) E6 protein and p53 phosphorylation status. Therefore, we used a mammalian green fluorescence protein (GFP) expression system to express HPV-16E6 with GFP fusion proteins in wild-type p53 cell lines, 293T, MCF-7, and SMMC-7721 to trace the traffic and subcellular location of E6 protein. By immunoblotting, we determined the positive phosphorylated sites of p53 in the context of HPV-16E6. Using immunofluorescence techniques, we observed the distribution of phosphorylated p53 in all the cells we used. In conclusion, HPV-16E6 was predominantly located in nuclei of wild-type p53 cells, and it was able to induce phosphorylation of p53 at multiple sites, such as Ser¹⁵, Ser²⁰, and Ser³⁹². The level and time of these phosphorylated sites of p53 were different in HPV-16E6 expressing cells. Furthermore, the phosphorylated p53 was localized in the nuclei together with HPV-16E6.