Journal: Cells
Article Title: Hepatitis C Virus Core Induces p53 Ser-15 Phosphorylation to Facilitate E6-Associated Protein-Mediated Proteasomal Degradation of p53
doi: 10.3390/cells15050415
Figure Lengend Snippet: HCV Core stimulates E6AP-mediated proteasomal degradation of p53 but inhibits MDM2-mediated degradation. HepG2 and Hep3B cells were transiently transfected with either an empty vector or the HCV Core expression plasmid, along with the indicated plasmids, for 48 h. For ( a ), HepG2-Core cells stably expressing HCV Core were also included. ( a , b ) Protein levels were measured by Western blot analysis. ( c ) Cells were treated with 50 μM cycloheximide (CHX) for the indicated times before harvesting, followed by Western blotting. Bands of p53 and γ-tubulin were quantified to determine the half-life (t1/2) of p53. The difference in the p53-to-γ-tubulin ratio among samples is shown in a graph. ( d , e ) Cells were treated with 10 μM MG132 for 4 h before harvesting to block further proteasomal degradation. For lanes 5 and 6 in ( e ), cells were treated with Nutlin 3a for 24 h. Total p53 was immunoprecipitated with an anti-p53 antibody and subjected to Western blotting using anti-E6AP, anti-MDM2, anti-HCV Core, and anti-HA antibodies to detect E6AP, MDM2, HCV Core, and HA-Ub-complexed p53, respectively. The input indicates the levels of the designated proteins in the cell lysates. ( f , g ) For mammalian two-hybrid assays, Hep3B cells were transfected with the Gal4 reporter (G5E1b-luc), pSG424-E6AP (or pSG424-MDM2), and pCMV p53-VP16, along with the indicated plasmids, for 48 h, followed by a luciferase assay. For ( f ), cells were treated with 10 μM MG132 for 4 h before harvesting. Luciferase activity from G5E1b-luc was normalized to the β-gal activity measured in the corresponding cell extract. The values show relative luciferase activity compared to the control’s basal level. Results are presented as mean ± SD from four independent experiments ( n = 4). ND, not detected.
Article Snippet: The HepG2 (#88065) and Hep3B (#88064) cell lines were purchased from the Korean Cell Line Bank (Seoul, Republic of Korea).
Techniques: Transfection, Plasmid Preparation, Expressing, Stable Transfection, Western Blot, Blocking Assay, Immunoprecipitation, Luciferase, Activity Assay