Heat Shock-Binding Protein 21 Regulates the Innate Immune Response to Viral Infection

The dual functions of KDM7A in HBV replication and immune microenvironment

KDM7A (lysine demethylase 7A, also known as JHDM1D) is a histone demethylase, it is mainly involved in the intracellular post-translational modifications process. Recently, it has been proved that the histone demethylase members can regulate the replication of hepatitis B virus (HBV) and the expression of key molecules in the Janus-activated kinase-signal transducer and activator of the transcription (JAK/STAT) signaling pathway by chromatin modifying mechanisms. In our study, we identify novel roles of KDM7A in HBV replication and immune microenvironment through two subjects: pathogen and host. On the one hand, KDM7A is highly expressed in HBV-infected cells and promotes HBV replication in vitro and in vivo. Moreover, KDM7A interacts with HBV covalently closed circular DNA and augments the activity of the HBV core promoter. On the other hand, KDM7A can remodel the immune microenvironment. It inhibits the expression of interferon-stimulated genes (ISGs) through the IFN-γ/JAK2/STAT1 signaling pathway in both hepatocytes and macrophages. Further study shows that KDM7A interacts with JAK2 and STAT1 and affects their methylation. In general, we demonstrate the dual functions of KDM7A in HBV replication and immune microenvironment, and then we propose a new therapeutic target for HBV infection and immunotherapy. IMPORTANCE Histone lysine demethylase KDM7A can interact with covalently closed circular DNA and promote the replication of hepatitis B virus (HBV). The IFN-γ/JAK2/STAT1 signaling pathway in macrophages and hepatocytes is also downregulated by KDM7A. This study provides new insights into the mechanism of HBV infection and the remodeling of the immune microenvironment.

ARIH1 inhibits influenza A virus replication and facilitates RIG-I dependent immune signaling by interacting with SQSTM1/p62

BACKGROUND

Multiple host factors are involved in modulating type I interferon expression induced by viruses; however, the mechanism is not fully elucidated. Influenza A virus infection causes severe respiratory symptoms and triggers a series of signaling cascades and host innate immune responses, including interferon production. The co-IP/MS technology was used to screen several antiviral factors in the early stage. Among these factors, ariadne-1 homolog (ARIH1) caught our attention.

METHODS

Western blot assay was performed to detect the level of proteins and software ImageJ was used to analyze the band intensities. Polymerase activity assay was conducted to evaluate the polymerase activity of influenza A virus. Tissue culture infective dose (TCID₅₀) assay was performed to measure influenza A virus titers, and quantitative RT-PCR assay was applied to test the mRNA level of IFN-β, ISG56, and CXCL10. Luciferase reporter assay was used to confirm the target of ARIH1 in RIG-I signaling. Immunoprecipitation assay was performed to detect the interaction and the ubiquitination of the proteins. All data were analyzed by biostatistical methods and presented as means ± standard deviation from three independent experiments. Statistical significance was determined using two-tailed student's t test. A P value of less than 0.05 was considered statistically significant, and a P value of less than 0.01 was considered highly significant (ns, P ≥ 0.05; *, P < 0.05; and **, P < 0.01).

RESULTS

We found that ARIH1, a member of E3 ubiquitin ligases, enhanced cellular antiviral responses. Subsequent study showed that ARIH1 was up-regulated during influenza A virus infection. Further analysis showed that ARIH1 enhanced IFN-β and downstream gene expression by affecting the degradation of RIG-I through the SQSTM1/p62 signaling pathway.

CONCLUSION

This newly revealed mechanism shows that cellular response increases of ARIH1 and promotes IFN-β expression to boost host survival during viral infection.

Screening for Lipid-Metabolism-Related Genes and Identifying the Diagnostic Potential of ANGPTL6 for HBV-Related Early-Stage Hepatocellular Carcinoma

Lipid metabolic reprogramming is one of the hallmarks of hepatocarcinogenesis and development. Therefore, lipid-metabolism-related genes may be used as potential biomarkers for hepatocellular carcinoma (HCC). This study aimed to screen for genes with dysregulated expression related to lipid metabolism in HCC and explored the clinical value of these genes. We screened differentially expressed proteins between tumorous and adjacent nontumorous tissues of hepatitis B virus (HBV)-related HCC patients using a Nanoscale Liquid Chromatography–Tandem Mass Spectrometry platform and combined it with transcriptomic data of lipid-metabolism-related genes from the GEO and HPA databases to identify dysregulated genes that may be involved in lipid metabolic processes. The potential clinical values of these genes were explored by bioinformatics online analysis tools (GEPIA, cBioPortal, SurvivalMeth, and TIMER). The expression levels of the secreted protein (angiopoietin-like protein 6, ANGPTL6) in serum were analyzed by ELISA. The ability of serum ANGPTL6 to diagnose early HCC was assessed by ROC curves. The results showed that serum ANGPTL6 could effectively differentiate between HBV-related early HCC patients with normal serum alpha-fetoprotein (AFP) levels and the noncancer group (healthy participants and chronic hepatitis B patients) (AUC = 0.717, 95% CI: from 0.614 to 0.805). Serum ANGPTL6 can be used as a potential second-line biomarker to supplement serum AFP in the early diagnosis of HBV-related HCC.