LAUSR

Aims: To investigate the role and underlying mechanism of 4E‐BP1 and S6K1 in regulating autophagy and hepatitis B virus (HBV) replication. Main methods: The mRNA relative expression of HBx and its DNA level were detected by real‐time PCR. The relative levels of hepatitis B surface antigen (HBsAg) were measured by enzyme‐linked immunosorbent assay (ELISA). HBx DNA level of HepG2 cells transfected with pcDNA3.1(+)‐HBV1.3 plasmids were detected by Southern blot. Moreover, we determined autophagy through electron microscopy, confocal microscopy and Western blot. Key findings: Rapamycin promoted autophagy and the X protein synthesis concomitantly with elevation in Akt phosphorylation and Beclin1 expression. Either Beclin1 or Akt depletion suppresses the Rapa‐enhanced HBV replication, whereas mTOR silencing inhibited HBV replication concurring with a decreased in both S6K1 and 4E‐BP1 phosphorylation. Unexpectedly, Akt inhibitor suppressed Rapa‐dependent autophagic flux and increased the level of p62/SQSTM1. While S6K1 ablation impaired autophagy and decreased X protein expression, 4E‐BP1 silencing slightly influenced autophagy and increased X protein level. Significance: The underlying mechanism of 4E‐BP1 and S6K1, two main downstream effectors of mTOR, in mediating HBV replication and HBV‐induced autophagy remains largely unknown. Here, we propose that Akt is required for both HBV replication and Rapa‐induced autophagy, and 4E‐BP1 and S6K1 play a distinct role in the virus replication and autophagic process.