The cooperative complex of Argonaute-2/MicroRNA-146a regulates Hepatitis B Virus replication through FEN1

Abstract Background: The regulatory of HBV replication is still unclear. FEN1 can repair HBV rcDNA to HBV cccDNA and promote HBV DNA replication. However, its specific regulatory detail remains unclear. MicroRNA regulates gene expression at post-transcriptional level. Especially, miR-146a, it plays an important role that is closely related to regulation of HBV replication. Based on above, we hypothesize that miR-146a may be regulate HBV cccDNA formation through FEN1. So, we will investigate the effect of miR-146a on the replication of hepatitis B virus and its molecular mechanism. Results: We found that level of miR-146a was significantly up-regulated in HepG2.2.15 cells (11.755±0.069) than that in HepG2 (1.000±0.038) (P<0.05). Furthermore, HBV-DNA copies and FEN1 were significantly increased and decreased, respectively, in HepG2.2.15 cells transfected with miR-146a mimic and inhibitor for 48h,[(3.215±0.001); (2.623±0.083)] compared with the control group (2.813±0.015) (P<0.05),. After transfection FEN1 plasmid, HBV-DNA Copies (5.712±0.371) is significantly higher than the control group（2.661±0.009）(P<0.05), and the level of miR-146a（3.431±0.004）is significantly higher than the control group (1.023±0.224） (P<0.05). The expression level of IRAK1/TRAF6 are significantly lower and higher [(0.114±0.013); (0.390±0.014); (1.222±0.073); (2.145±0.271)] than the control group [(1.000±0.038); (1.007±0.119)] (P<0.05) after transfection miR-146a mimic and inhibitor into HepG2.2.15. After Ago2 siRNA, the level of miR-146a (0.105±0.002) is significantly decreased than the control group (1.000±0.041) (P<0.05) from Ago2 protein RIP. After transfection Ago2 siRNA then added into exogenous miR-146a into HepG2.2.15, The expression level of FEN1 is significantly reduced (0.485±0.100) than the control group (1.000±0.023) (P<0.05), and the HBV-DNA copies is significantly lower (3.230±0.047) than the control group (3.789±0.041) (P<0.05). Conclusion: Ago2 cooperates with miR-146a to regulate the transcription the expression level of FEN1 protein through the downstream target gene IRAK1/TRAF6, then promoting HBV replication.