Fig. 4

HBV-DNA-Pol upregulates PD-L1 expression via PARP1. A HBV-DNA-Pol does not impact PARP1 protein levels. Extracts from the HBV-DNA-Pol⁺ Huh7 cells or control cells were collected and subjected to Western blotting with anti-PARP1 and anti-GAPDH antibodies. B, C HBV-DNA-Pol inhibits nuclear translocation of PARP1. B HBV-DNA-Pol⁺ Huh7 cells or control cells were subjected to immunofluorescent staining with antibody against PARP1 and stained with DAPI to visualize the nuclei. The images were digitally merged. Scale bar, 10 μm. C Western blotting were used to detect PARP1 protein levels in nucleoplasm or cytoplasm from HBV-DNA-Pol⁺ Huh7 cells and control cells. D, E The effect of HBV-DNA-Pol on PARP1 is dependent on their interaction. D Huh7 cells were transfected with the indicated plasmids. Then nucleoplasmic or cytoplasmic extracts were harvested at 48 h post-transfection and analyzed by Western blotting with anti-PARP1, anti-GAPDH and anti-LMNB1 antibodies. E Huh7 cells were transfected with the indicated plasmids and then immunofluorescence assays were performed with anti-PARP1 antibody. The images were digitally merged. Scale bar, 10 μm. F PARP1 negatively regulates the expression of PD-L1. Huh7 cells were transfected with the indicated plasmids. Extracts were collected at 48 h post-transfection and PD-L1 expression was analyzed by Western blotting and qRT-PCR assays. G HBV-DNA-Pol upregulates PD-L1 expression via PARP1. Huh7 cells were transfected with the indicated plasmids. Extracts were collected at 48 h post-transfection and PD-L1 expression was analyzed by Western blotting and qRT-PCR assays