Mitochondrial DNA is a target of HBV integration

Potentials as biomarker and therapeutic target of upregulated long non-coding RNA HLA-F antisense RNA 1 in hepatitis B virus-associated hepatocellular carcinoma

The tissue-specific characteristics have encouraged researchers to identify organ-specific lncRNAs as disease biomarkers. This study aimed to identify the clinical and functional roles of long non-coding RNA HLA-F antisense RNA 1 (HLA-F-AS1) in hepatitis B virus (HBV)-hepatocellular carcinoma (HCC). A total of 121 HBV-HCC, 81 chronic hepatitis B (CHB), and 85 normal liver tissues were evaluated in this study. Real-time quantitative PCR assay was used to evaluate the RNA expression levels. Performance in diagnosis was compared between alpha fetoprotein (AFP) and HLA-F-AS1 using Receiver Operating Characteristic (ROC) curves. Performance in post-hepatectomy prognosis with high or low HLA-F-AS1 was compared using Kaplan-Meier curves. Multi-variable analysis was used to determine the informative predictors. Downstream miRNAs for HLA-F-AS1 were predicted and miR-128-3p was confirmed by luciferase reporter assay and RNA pull-down assay. In vitro functional analysis was performed by MTS reagent for cell proliferation and transwell assay for cell migration. HLA-F-AS1 levels were significantly increased in the HBV-HCC compared to normal healthy tissue and CHB tissues. HLA-F-AS1 exhibited a well potential in making a distinction between HBV-HCC and health, as well as HBV-HCC and CHB. The survival analysis revealed that patients with high levels of HLA-F-AS1 tend to shorter overall survival times. The best prognostic performance was achieved by HLA-F-AS1 after multi-variable analysis (HR 2.290, 95% CI 1.191-4.403, p = 0.013). Functional analysis showed that HLA-F-AS1 promoted cell proliferation and migration via miR-128-3p. Up-regulation of HLA-F-AS1 could serve as a promising diagnostic and prognostic marker for HBV-HCC after surgery, maybe useful in the management of HBV-HCC patients. HLA-F-AS1 can promote the progression of HBV-HCC, may be useful in the targeting treatment of HBV-HCC patients.

Mitochondrial Oxidative Phosphorylation in Viral Infections

Mitochondria have been identified as the "powerhouse" of the cell, generating the cellular energy, ATP, for almost seven decades. Research over time has uncovered a multifaceted role of the mitochondrion in processes such as cellular stress signaling, generating precursor molecules, immune response, and apoptosis to name a few. Dysfunctional mitochondria resulting from a departure in homeostasis results in cellular degeneration. Viruses hijack host cell machinery to facilitate their own replication in the absence of a bonafide replication machinery. Replication being an energy intensive process necessitates regulation of the host cell oxidative phosphorylation occurring at the electron transport chain in the mitochondria to generate energy. Mitochondria, therefore, can be an attractive therapeutic target by limiting energy for viral replication. In this review we focus on the physiology of oxidative phosphorylation and on the limited studies highlighting the regulatory effects viruses induce on the electron transport chain.

The role of hepatocyte mitochondrial DNA in liver injury

Hepatocytes, the predominant cellular constituents of the liver, exhibit the highest mitochondrial density within the human body. Remarkably, experimental insights from the latter part of the previous century involving extracellular injection of mitochondrial DNA (mtDNA) elucidated its potential to incite autoimmune disorders. Consequently, in instances of liver injury, the substantial release of mtDNA has the potential to trigger the activation of the innate immune response, thereby inducing sustained pathogenic consequences within the organism. This article provides a comprehensive retrospective analysis of recent literature pertaining to the impact of mtDNA release on various hepatic cell populations, elucidating its role and potential mechanisms in liver injury. The findings underscore the central role of mtDNA in modulating the immune system, primarily through the orchestration of a cytokine storm, further exacerbating the occurrence of liver injury.

Regulation of Mitochondrial Metabolism by Hepatitis B Virus

Mitochondria play important roles in the synthesis of ATP, the production of reactive oxygen species, and the regulation of innate immune response and apoptosis. Many viruses perturb mitochondrial activities to promote their replication and cause cell damage. Hepatitis B virus (HBV) is a hepatotropic virus that can cause severe liver diseases, including cirrhosis and hepatocellular carcinoma (HCC). This virus can also alter mitochondrial functions and metabolism to promote its replication and persistence. In this report, we summarize recent research progress on the interaction between HBV and mitochondrial metabolism, as well as the effect this interaction has on HBV replication and persistence.

The Initial Hepatitis B Virus-Hepatocyte Genomic Integrations and Their Role in Hepatocellular Oncogenesis

Hepatitis B virus (HBV) remains a dominant cause of hepatocellular carcinoma (HCC). Recently, it was shown that HBV and woodchuck hepatitis virus (WHV) integrate into the hepatocyte genome minutes after invasion. Retrotransposons and transposable sequences were frequent sites of the initial insertions, suggesting a mechanism for spontaneous HBV DNA dispersal throughout the hepatocyte genome. Several somatic genes were also identified as early insertional targets in infected hepatocytes and woodchuck livers. Head-to-tail joints (HTJs) dominated amongst fusions, indicating their creation by non-homologous end-joining (NHEJ). Their formation coincided with the robust oxidative damage of hepatocyte DNA. This was associated with the activation of poly(ADP-ribose) polymerase 1 (PARP1)-mediated dsDNA repair, as reflected by the augmented transcription of PARP1 and XRCC1; the PARP1 binding partner OGG1, a responder to oxidative DNA damage; and increased activity of NAD+, a marker of PARP1 activation, and HO1, an indicator of cell oxidative stress. The engagement of the PARP1-mediated NHEJ repair pathway explains the HTJ format of the initial merges. The findings show that HBV and WHV are immediate inducers of oxidative DNA damage and hijack dsDNA repair to integrate into the hepatocyte genome, and through this mechanism, they may initiate pro-oncogenic processes. Tracking initial integrations may uncover early markers of HCC and help to explain HBV-associated oncogenesis.