Figure 3. TSPX mediates HBx degradation through ubiquitin-proteasome pathway.

Ubiquitin-activating enzyme inhibitor PYR-41 inhibits TSPX-mediated enhancement of HBx-degradation. HA-HBx expression vector (0.2 µg/well) and DsRed-V5 expression vector (0.1 µg/well) were co-transfected into 293T cells with FLAG-TSPX[ΔPro] (0.05 µg/well). Twenty-four hours after transfection, cells were treated with either vehicle (DMSO) or 50 µM PYR-41 for additional 24 h. Cell lysates were analyzed by Western blot using anti-HA, anti-V5 and anti-FLAG antibodies. Treatment with PYR-41 significantly increased the HA-HBx even in the presence of TSPX.