EFFECTS OF IFN-λ3 ON SUBCELLULAR PROTEOME IN HEPATITIS B VIRUS-TRANSFECTED CELLS

Abstract

Chronic HBV infection can develop severe and mortal liver diseases such as cirrhosis and hepatocellular carcinoma (HCC) causing 600,000 deaths annually. The current anti-HBV treatments have some limitations. Therefore, the novel drugs overcoming these restrictions are still needed. Interferon-λ (IFN-λ) is a cytokine with activities like type I IFN but it has less unfavorable side effects than IFN-α because of the restriction of its receptor expression. With these reasons, IFN-λ might be a novel drug for treating patients with CHB. In this study, we demonstrated that IFN-λ3, the most potent subtypes, could induce the expression of ISGs and suppress HBV replication and HBV gene expression in a dose-dependent manner in HBV-transfected HepG2.2.15 cells. Surprisingly, the potency of IFN-λ3 were higher than peg-IFN-α2b which is the drug that treat the patients with CHB in current. To investigate the molecular mechanism of IFN-λ3, proteomics together with subcellular fractionation which is the method enriching low-abundant proteins were performed to compare the global proteome responses between HepG2.2.15 and HepG2.2.15 treated with IFN-λ3. All three subcellular extracts were assessed their purity by western blot and the result indicated that proteins of each fraction were quite pure. The proteins of three fractions from HepG2.2.15 before and after IFN-λ3 treatment were separated by 2-DE and the differentially expressed proteins were subsequently identified by mass spectrometer. A total of 69 differentially expressed proteins were successfully identified in HepG2.2.15 treated with IFN-λ3. These proteins were involved in proteolysis pathway, cell proliferation, heat shock proteins, etc. We selected some important proteins to confirm their expression by WB e.g, 14-3-3, proteasome and calreticulin. Based on our results, we proposed that IFN-λ3 exhibited both antiviral and immunomodulatory effects to control HBV infection. Therefore, IFN-λ3 is an attractive novel candidate for CHB treatment and the altered proteins might be new therapeutic target in CHB infection. However, further studies on IFN-λ3 itself and the functional studies of altered proteins are needed.