Activation of the Mitochondrial Apoptotic Signaling Platform during Rubella Virus Infection

Claus, Claudia; Manssen, Lena; Hübner, Denise; Roßmark, Sarah; Bothe, Viktoria; Petzold, Alice; Große, Claudia; Reins, Mareen; Mankertz, Annette; Frey, Teryl K.; Liebert, Uwe G.

In comparison to the SC, application of PFTµ induced a massive p53 nuclear localization in RV-infected Vero cells at 3 dpi. The results for the SC-treated mock cell population are representative for the application of NIM811 and PFTµ. Western blot analysis of nuclear fractions confirmed the increased nuclear localization of p53 after application of PFTµ ( Figure 5C ). Additionally, and in contrast to the mock-infected population, Western blot analysis of mitochondria-enriched fractions from the RV-infected, SC-treated Vero cell population showed an increased band intensity for p53 which was reduced after application of PFTµ ( Figure 5D ). Application of NIM811 had no detectable effect on the level of p53 within the mitochondria-enriched fraction. Subsequently immunofluorescence analysis of the intracellular distribution of p53 and the mitochondria-associated viral C protein revealed punctate staining of p53 outside of the nucleus, close to C protein-positive areas ( Figure 5E ). These areas overlap with an area of clustered mitochondria typical for RV-infected Vero cells, which have a highly intense MitoTracker DeepRed CMX Ros staining ( Figure 5E , shown in white). In summary, RV induces mitochondrial and nuclear translocation of p53. Whereas the former decreased after application of 12.5 µM PFTµ, the latter increased.