Peroxisome proliferator-activated receptor γ coactivator family members competitively regulate hepatitis b virus biosynthesis

Glucose-stimulated PGC-1α couples with CBP and Runx2 to mediate intervertebral disc degeneration through transactivation of ADAMTS4/5 in diet-induced obesity mice

Emerging evidence suggests that type 2 diabetes mellitus (T2DM) is associated with the pathogenesis of intervertebral disc degeneration (IDD). However, it is still unclear how T2DM contributes to IDD. Herein, we observed the accumulation of blood glucose and degenerative lumbar discs in mice fed a high-fat diet. Detection of differentially expressed genes in degenerative lumbar discs revealed that ADAMTS4 (A Disintegrin and Metalloproteinase with Thrombospondin motifs) and ADAMTS5 genes were significantly increased. In vitro analyses demonstrated that Runt-Related Transcription Factor 2 (Runx2) recruited both PPARgamma Coactivator 1alpha (PGC-1α) and CREB-Binding Protein (CBP) to transactivate the expression of ADAMTS4/5. Glucose stimulation could dose-dependently induce the accumulation of PGC-1α and promoted the binding of the CBP-PGC-1α-Runx2 complex to the promoters of ADAMTS4/5. Depletion of CBP-PGC-1α-Runx2 complex members and treatment with either PGC-1α inhibitor SR-18292 or CBP inhibitor EML425 in vitro could dramatically inhibit the glucose-induced expression of ADAMTS4/5. Administration of SR-18292 and EML425 in diabetic mice could prevent the degeneration of lumbar discs. Collectively, our results revealed a molecular mechanism by which the hyperglycemia-dependent CBP-PGC-1α-Runx2 complex was required for the transactivation of ADAMTS4/5. The blockage of this complex in diabetic mice may help prevent IDD.

B-Catenin Signaling Regulates the In Vivo Distribution of Hepatitis B Virus Biosynthesis across the Liver Lobule

β-catenin (Ctnnb1) supports high levels of liver gene expression in hepatocytes in proximity to the central vein functionally defining zone 3 of the liver lobule. This region of the liver lobule supports the highest levels of viral biosynthesis in wildtype HBV transgenic mice. Liver-specific β-catenin-null HBV transgenic mice exhibit a stark loss of high levels of pericentral viral biosynthesis. Additionally, viral replication that does not depend directly on β-catenin activity appears to expand to include hepatocytes of zone 1 of the liver lobule in proximity to the portal vein, a region of the liver that typically lacks significant HBV biosynthesis in wildtype HBV transgenic mice. While the average amount of viral RNA transcripts does not change, viral DNA replication is reduced approximately three-fold. Together, these observations demonstrate that β-catenin signaling represents a major determinant of HBV biosynthesis governing the magnitude and distribution of viral replication across the liver lobule in vivo. Additionally, these findings reveal a novel mechanism for the regulation of HBV biosynthesis that is potentially relevant to the expression of additional liver-specific genes. IMPORTANCE Viral biosynthesis is highest around the central vein in the HBV transgenic mouse model of chronic infection. The associated HBV biosynthetic gradient across the liver lobule is primarily dependent upon β-catenin. In the absence of β-catenin, the gradient of viral gene expression spanning the liver lobule is absent and HBV replication is reduced. Therefore, therapeutically manipulating β-catenin activity in the liver of chronic HBV carriers may reduce circulating infectious virions without greatly modulating viral protein production. Together, these change in viral biosynthesis might limit infection of additional hepatocytes while permitting immunological clearance of previously infected cells, potentially limiting disease persistence.

Antiviral mechanism of preclinical antimalarial compounds possessing multiple antiviral activities

We previously found that N‐89 and its derivative, N‐251, which are being developed as antimalarial compounds, showed multiple antiviral activities including hepatitis C virus (HCV). In this study, we focused on the most characterized anti‐HCV activity of N‐89(N‐251) to clarify their antiviral mechanisms. We first prepared cells exhibiting resistance to N‐89(N‐251) than the parental cells by serial treatment of HCV–RNA‐replicating parental cells with N‐89(N‐251). Then, we newly generated HCV–RNA‐replicating cells with the replacement of HCV–RNAs derived from N‐89(N‐251)‐resistant cells and parental cells. Using these cells, we examined the degree of inhibition of HCV–RNA replication by N‐89(N‐251) and found that the host and viral factors contributed almost equally to the resistance to N‐89(N‐251). To further examine the contribution of the host factors, we selected several candidate genes by cDNA microarray analysis and found that the upregulated expression of at least RAC2 and CKMT1B genes independently and differently contributed to the acquisition of an N‐89(N‐251)‐resistant phenotype. For the viral factors, we selected several mutation candidates by the genetic comparative analysis of HCV–RNAs and showed that at least one M414I mutation in the HCV NS5B contributed to the resistance to N‐89. Moreover, we demonstrated that the combination of host factors (RAC2 and/or CKMT1B) and a viral factor (M414I mutation) additively increased the resistance to N‐89. In summary, we identified the host and viral factors contributing to the acquisition of N‐89(N‐251)‐resistance in HCV–RNA replication. These findings will be useful for clarification of the antiviral mechanism of N‐89(N‐251).

Hepatitis B Virus Infection: Overview

Hepatitis B virus (HBV) is a DNA virus, belonging to the Hepadnaviridae family. It is a partially double-stranded DNA virus with a small viral genome (3.2 kb). Chronic HBV infection remains a global public health problem. If left untreated, chronic HBV infection can progress to end-stage liver disease, such as liver cirrhosis and hepatocellular carcinoma (HCC). In recent years, tremendous advances in the field of HBV basic and clinical research have been achieved, ranging from the HBV biological characteristics, immunopathogenesis, and animal models to the development of new therapeutic strategies and new drugs against HBV. In this overview, we begin with a brief history of HBV discovery and treatment milestones. We then briefly summarize the HBV research advances, which will be detailed in the following chapters.

Mito-Nuclear Communication in Hepatocellular Carcinoma Metabolic Rewiring

As the main metabolic and detoxification organ, the liver constantly adapts its activity to fulfill the energy requirements of the whole body. Despite the remarkable adaptive capacity of the liver, prolonged exposure to noxious stimuli such as alcohol, viruses and metabolic disorders results in the development of chronic liver disease that can progress to hepatocellular carcinoma (HCC), which is currently the second leading cause of cancer-related death worldwide. Metabolic rewiring is a common feature of cancers, including HCC. Altered mito-nuclear communication is emerging as a driving force in the metabolic reprogramming of cancer cells, affecting all aspects of cancer biology from neoplastic transformation to acquired drug resistance. Here, we explore relevant aspects (and discuss recent findings) of mito-nuclear crosstalk in the metabolic reprogramming of hepatocellular carcinoma.