Hepatocyte Factor JMJD5 Regulates Hepatitis B Virus Replication through Interaction with HBx

Area of Science:

• Hepatology and Viral Hepatitis Research
• Molecular Biology of Viral Infections
• Protein-Protein Interactions in Disease

Background:

• Hepatitis B virus (HBV) causes chronic liver diseases, including hepatocellular carcinoma (HCC).
• The HBV-X (HBx) protein is vital for HBV pathogenesis and replication.
• Mechanisms of HBx-mediated HBV replication are not fully understood.

Purpose of the Study:

• Identify novel binding partners of HBx.
• Elucidate the role of HBx-interacting proteins in HBV replication.
• Investigate the functional significance of HBx-JMJD5 interaction.

Main Methods:

• Co-immunoprecipitation to identify HBx binding partners.
• JMJD5 knockout Huh7 cell models.
• DNA microarray analysis for gene expression profiling.
• Mutagenesis to assess protein interaction and function.

Main Results:

• Jumonji C-domain-containing 5 (JMJD5) was identified as a novel cytoplasmic binding partner of HBx.
• JMJD5 knockout cells showed reduced expression of hepatocyte differentiation factors (HNF4A, CEBPA, FOXA3).
• JMJD5 hydroxylase activity is essential for regulating these factors and for HBV replication.
• A specific mutation in JMJD5 (G135E) abolished HBx binding and HBV replication.

Conclusions:

• JMJD5 directly interacts with HBx, facilitating HBV replication.
• JMJD5’s hydroxylase activity is critical for this interaction and subsequent viral replication.
• Targeting the HBx-JMJD5 interaction may offer a novel therapeutic strategy for HBV infection.