Novel Function of NUP153 in HNF4α Transcriptional Upregulation Contributes to Promoting HBV Replication.

Hepatitis B virus (HBV) infection remains a major public health problem, causing nearly one million deaths annually. Nucleoporin 153 (NUP153) is known to facilitate the nuclear entry of the human immunodeficiency virus (HIV) nucleocapsids, and recent studies suggest it also plays a role in HBV nucleocapsids nuclear import. We aimed to investigate the impact of NUP153 on HBV replication and its underlying mechanism. NUP153 was knocked down by RNA interference or CRISPR/Cas9-mediated gene disruption, or overexpressed using an expression plasmid in HBV-replicating cells and animal model. Luciferase reporter assays were employed to assess the activities of viral or host factor promoters. Cytoplasmic and nuclear fractionation experiments were conducted to analyze the subcellular distribution of proteins and HBV RNA. In the present study, we found that knockdown of NUP153 significantly inhibited HBV replication without affecting the levels of covalently closed circular DNA (cccDNA) in both the prcccDNA/Cre recombinant plasmid system and HepG2-NTCP cells. Consistent results were observed in a mouse model hydrodynamically injected (HDI) with 1.2 × HBV plasmid. Conversely, NUP153 overexpression markedly increased cccDNA transcription and progeny virus production. Further study revealed that NUP153 enhanced HBV core promoter activity, likely through a hepatocyte nuclear factor 4α (HNF4α)-dependent mechanism. Mechanistically, ERK signaling was essential for NUP153-mediated promotion of HNF4α and HBV replication. Additionally, HBV replication significantly upregulated NUP153 mRNA and protein levels in both HBV cell models and HBV-infected patients. Together, we identify NUP153 as a novel host factor that promotes HBV replication by enhancing cccDNA transcription through the upregulation of HNF4α, suggesting a potential therapeutic strategy for HBV replication.