Cellular protein TIA-1 regulates the expression of HBV surface antigen by binding the HBV posttranscriptional regulatory element

Objective: To identify T-cell intracellular antigen 1 (TIA-1) interacting with the posttranscriptional regulatory element (PRE) of hepatitis B virus (HBV), and reveal TIA-1 function on HBV gene expression. Methods: In order to demonstrate TIA-1 binding to PRE, electrophoretic mobility shift and RNA and protein pull-down assays were used. The pDM138-PRE reporter system, HepG2.2.15 cell line and HBs-PRE transient expression cells were adopted to identify TIA-1 function in the HBV life cycle. Results: TIA-1 could directly bind to PRE RNA. The functional binding region of TIA-1 was identified. Functional analysis indicated that TIA-1 could dose-dependently inhibit PRE function in pDM138-PRE system. Down-expression of HBs antigen induced by TIA-1 was detected both in the HepG2.2.15 cell line and in HBs-PRE transient expression cells. Conclusion: These data demonstrated that TIA-1 inhibits HBs expression by interacting with PRE. Copyright (C) 2008 S. Karger AG, Basel.