RESUMO
Hepatitis B virus (HBV) infection is a major cause of acute and chronic liver diseases. During the HBV life cycle, HBV hijacks various host factors to assist viral replication. In this research, we find that the HBV regulatory protein X (HBx) can induce the upregulation of DExH-box RNA helicase 9 (DHX9) expression by repressing proteasome-dependent degradation mediated by MDM2. Furthermore, we demonstrate that DHX9 contributes to viral DNA replication in dependence on its helicase activity and nuclear localization. In addition, the promotion of viral DNA replication by DHX9 is dependent on its interaction with Nup98. Our findings reveal that HBx-mediated DHX9 upregulation is essential for HBV DNA replication.
Assuntos
RNA Helicases DEAD-box/metabolismo , Vírus da Hepatite B/fisiologia , Hepatite B/metabolismo , Proteínas de Neoplasias/metabolismo , Complexo de Proteínas Formadoras de Poros Nucleares/metabolismo , Transativadores/fisiologia , Proteínas Virais Reguladoras e Acessórias/fisiologia , Animais , Linhagem Celular , Núcleo Celular/metabolismo , RNA Helicases DEAD-box/genética , Replicação do DNA , DNA Viral , Regulação da Expressão Gênica , Células HEK293 , Células Hep G2 , Hepatite B/genética , Hepatite B/virologia , Interações entre Hospedeiro e Microrganismos , Humanos , Camundongos , Camundongos Transgênicos , Proteínas de Neoplasias/genética , Regulação para Cima , Replicação ViralRESUMO
Hepatitis B virus (HBV) is a partially double-stranded DNA virus that replicates by reverse transcription. We previously demonstrated that the host restriction factor-APOBEC3B (A3B) inhibited HBV replication which was dependent on its deaminase activity during reverse transcription. However, the host factors involved in the process of regulating the anti-HBV function of A3B are less known. In this research, to obtain a comprehensive understanding of the interaction networks of A3B, we conducted coimmunoprecipitation and mass spectrometry to identify A3B-interacting proteins in the presence of HBV. By this approach, we determined that DExD/H-box helicase 9 (DHX9) suppressed the anti-HBV effect of A3B, and this suppression was dependent on their interaction. Although DHX9 did not affect the deamination activity of A3B in vitro assay or the viral DNA editing of A3B in HepG2-NTCP cells that support HBV infection, it inhibited the binding of A3B with pgRNA. These data suggest that DHX9 can interact with A3B and attenuate the anti-HBV efficacy of A3B.Abbreviations: 3D-PCR: differential DNA denaturation PCR; APOBEC3: apolipoprotein B mRNA-editing catalytic polypeptide 3; cccDNA: covalently closed circular DNA; co-IP: coimmunoprecipitation; DDX: DExD-box RNA helicases; HBc: HBV core protein; HBV: hepatitis B virus; HepAD38: HepG2 cell line stably transfected with HBV DNA; HepG2-NTCP: HepG2 cell line stably transfected with Na+/taurocholate cotransporter polypeptide; Huh7: human hepatoma cell line; pgRNA: pregenomic RNA; PPI: protein-protein interactions; RC DNA: relaxed circular DNA.