All-trans Retinoic Acid Inhibits Hepatitis B Virus Replication by Downregulating HBx Levels via Siah-1-Mediated Proteasomal Degradation

• Published in: Viruses Vol. 15; no. 7; p. 1456
• Main Authors: Han, Jiwoo, Jang, Kyung Lib
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 27.06.2023; MDPI
• Subjects: all-trans retinoic acid; Biological activity; Cell culture; Cell growth; chemoprevention; Degradation; Genes; Genomes; HBV; HBx; Hepatitis B; Hepatitis B virus; Hepatocellular carcinoma; hepatoma; Infections; Kinases; Leukemia; Liver cancer; Metabolism; Metabolites; p53; Plasmids; Polyethylene glycol; Proteasomes; Proteins; Replication; Retinoic acid; Siah-1; Signal transduction; therapeutics; Ubiquitin-protein ligase; Ubiquitination; ubiquitin–proteasome system; virus replication; Vitamin A; United States > US; South Korea; Germany; all-trans retinoic acid; ubiquitin–proteasome system; HBV; Siah-1; HBx; p53
• ISSN: 1999-4915; 1999-4915
• DOI: 10.3390/v15071456

All-trans retinoic acid (ATRA), the most biologically active metabolite of vitamin A, is known to abolish the potential of HBx to downregulate the levels of p14, p16, and p21 and to stimulate cell growth during hepatitis B virus (HBV) infection, contributing to its chemopreventive and therapeutic effects against HBV-associated hepatocellular carcinoma. Here, we demonstrated that ATRA antagonizes HBx to inhibit HBV replication. For this effect, ATRA individually or in combination with HBx upregulated p53 levels, resulting in upregulation of seven in absentia homolog 1 (Siah-1) levels. Siah-1, an E3 ligase, induces ubiquitination and proteasomal degradation of HBx in the presence of ATRA. The ability of ATRA to induce Siah-1-mediated HBx degradation and the subsequent inhibition of HBV replication was proven in an in vitro HBV replication model. The effects of ATRA became invalid when either p53 or Siah-1 was knocked down by a specific shRNA, providing direct evidence for the role of p53 and Siah-1 in the negative regulation of HBV replication by ATRA.