Epigallocatechin-3-gallate suppresses HBV replication via a GPX4-dependent axis that triggers phosphorylation-coupled degradation of HNF4α

HNF4α functions as a pivotal transcription factor and master regulator of Hepatitis B Virus (HBV), directly binding to the viral promoter to facilitate pre-genomic RNA synthesis. However, its ligand-binding pocket, characterized by a lengthy and shallow hydrophobic groove occupied by endogenous fatty acids, hinders the binding of conventional small-molecule inhibitors. We employed a “degradation-over-inhibition” strategy to screen for compounds capable of eliminating HNF4α. Epigallocatechin-3-gallate (EGCG), a prominent polyphenol in green tea, emerged as a selective inducer of HNF4α degradation. Mechanistic studies were performed in HBV-replicating cells to elucidate the signaling cascade activated by EGCG. EGCG treatment resulted in the down-regulation of glutathione peroxidase 4, leading to the accumulation of reactive oxygen species (ROS), activation of AMPK, and site-specific phosphorylation of HNF4α. This phosphorylation targeted HNF4α for ubiquitin-proteasome-mediated degradation, significantly suppressing HBV replication. Our findings reveal a phosphorylation-driven degradation pathway that effectively eliminates HNF4α, thereby inhibiting HBV. This strategy not only presents a novel antiviral approach but also offers a general framework for addressing “undruggable” transcription factors with shallow binding pockets that resist traditional small-molecule inhibitors.