Regulation of the Hepatitis B virus replication and gene expression by the multi-functional protein TARDBP

• Published in: Scientific reports 2019-06, Vol.9 (1), p.8462, Article 8462
• Main Authors: Makokha, Grace Naswa, Abe-Chayama, Hiromi, Chowdhury, Sajeda, Hayes, C. Nelson, Tsuge, Masataka, Yoshima, Tadahiko, Ishida, Yuji, Zhang, Yizhou, Uchida, Takuro, Tateno, Chise, Akiyama, Rie, Chayama, Kazuaki
• Format: Article
• Language: English
• Subjects: 13/109; 38/77; 38/89; 42; 42/70; 631/326/596/1550; 631/326/596/2557; 82; 82/29; 82/58; 82/83; Base Sequence; Binding Sites - genetics; Cell Nucleus - metabolism; Chromatin; CRISPR-Cas Systems - genetics; Deoxyribonucleic acid; DNA; DNA-Binding Proteins - metabolism; Drug development; Ectopic expression; Gene expression; Gene Expression Regulation, Viral; Gene Silencing; Hep G2 Cells; Hepatitis; Hepatitis B; Hepatitis B - virology; Hepatitis B virus - genetics; Hepatitis B virus - physiology; Hepatocellular carcinoma; Hsp90 protein; Humanities and Social Sciences; Humans; Intermediates; Life cycles; multidisciplinary; Mutagenesis; Nuclear transport; Nucleophosmin; Poly(ADP-ribose) polymerase; Promoter Regions, Genetic - genetics; Proteins; Replication; Replicative intermediates; Risk factors; RNA Recognition Motif - genetics; RNA Splicing - genetics; Science; Science (multidisciplinary); Splicing; Transcription, Genetic; Virions; Virus Replication - genetics
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-019-44934-5

Hepatitis B virus (HBV) infects the liver and is a key risk factor for hepatocellular carcinoma. Identification of host factors that support viral replication is important to understand mechanisms of viral replication and to develop new therapeutic strategies. We identified TARDBP as a host factor that regulates HBV. Silencing or knocking out the protein in HBV infected cells severely impaired the production of viral replicative intermediates, mRNAs, proteins, and virions, whereas ectopic expression of TARDBP rescued production of these products. Mechanistically, we found that the protein binds to the HBV core promoter, as shown by chromatin precipitation as well as mutagenesis and protein-DNA interaction assays. Using LC-MS/MS analysis, we also found that TARDBP binds to a number of other proteins known to support the HBV life cycle, including NPM1, PARP1, Hsp90, HNRNPC, SFPQ, PTBP1, HNRNPK, and PUF60. Interestingly, given its key role as a regulator of RNA splicing, we found that TARDBP has an inhibitory role on pregenomic RNA splicing, which might help the virus to export its non-canonical RNAs from the nucleus without being subjected to unwanted splicing, even though mRNA nuclear export is normally closely tied to RNA splicing. Taken together, our results demonstrate that TARDBP is involved in multiple steps of HBV replication via binding to both HBV DNA and RNA. The protein’s broad interactome suggests that TARDBP may function as part of a RNA-binding scaffold involved in HBV replication and that the interaction between these proteins might be a target for development of anti-HBV drugs.