Knockdown of damage-specific DNA binding protein 1 (DDB1) enhances the HBx-siRNA-mediated inhibition of HBV replication

Silicon Nanowire Field-Effect Transistor as Label-Free Detection of Hepatitis B Virus Proteins with Opposite Net Charges

The prevalence of hepatitis B virus (HBV) is a global healthcare threat, particularly chronic hepatitis B (CHB) that might lead to hepatocellular carcinoma (HCC) should not be neglected. Although many types of HBV diagnosis detection methods are available, some technical challenges, such as the high cost or lack of practical feasibility, need to be overcome. In this study, the polycrystalline silicon nanowire field-effect transistors (pSiNWFETs) were fabricated through commercial process technology and then chemically functionalized for sensing hepatitis B virus surface antigen (HBsAg) and hepatitis B virus X protein (HBx) at the femto-molar level. These two proteins have been suggested to be related to the HCC development, while the former is also the hallmark for HBV diagnosis, and the latter is an RNA-binding protein. Interestingly, these two proteins carried opposite net charges, which could serve as complementary candidates for evaluating the charge-based sensing mechanism in the pSiNWFET. The measurements on the threshold voltage shifts of pSiNWFETs showed a consistent correspondence to the polarity of the charges on the proteins studied. We believe that this report can pave the way towards developing an approachable tool for biomedical applications.

RPB5-Mediating Protein Suppresses Hepatitis B Virus (HBV) Transcription and Replication by Counteracting the Transcriptional Activation of Hepatitis B virus X Protein in HBV Replication Mouse Model

Background:

RPB5-Mediating protein (RMP) is associated with the RNA polymerase II subunit RPB5. This protein functionally counteracts the transcriptional activation of Hepatitis B Virus X protein (HBx) by competitively binding to the RPB5; however, the effects of RMP on Hepatitis B virus (HBV) transcription and replication remain unknown.

Objectives:

The purpose of this study was to investigate the effect of RMP on viral transcription and replication in vivo by using the hydrodynamic-based HBV replication mouse model.

Materials and Methods:

Male balb/c mice were transfected with wild type (1.2 wt) or the HBx minus HBV plasmids (1.2x (-)) with or without HBx and RMP, to establish an HBV replication mouse model by hydrodynamic injection through the tail vein. The HBV RNA and HBV DNA replication intermediates (RI) were analyzed in the liver.

Results:

RPB5-Mediating protein could inhibit HBV transcription and replication in groups transfected with the 1.2 wt and HBx. The inhibitory effect disappeared in the 1.2x (-) groups, yet it reappeared in the groups co-transfected with 1.2x (-) and HBx. An inhibitory effect was indicated at a low dose of RMP (0.3 ug, 0.5 ug and 0.7 ug) compared to the control group and groups that had received high doses of RMP.

Conclusions:

Our study demonstrated that a low dose of RMP could inhibit HBV transcription and replication, which is dependent on the appearance of HBx in vivo.

RNAi and miRNA in viral infections and cancers

Since the first report of RNA interference (RNAi) less than a decade ago, this type of molecular intervention has been introduced to repress gene expression in vitro and also for in vivo studies in mammals. Understanding the mechanisms of action of synthetic small interfering RNAs (siRNAs) underlies use as therapeutic agents in the areas of cancer and viral infection. Recent studies have also promoted different theories about cell-specific targeting of siRNAs. Design and delivery strategies for successful treatment of human diseases are becomingmore established and relationships between miRNA and RNAi pathways have been revealed as virus-host cell interactions. Although both are well conserved in plants, invertebrates and mammals, there is also variabilityand a more complete understanding of differences will be needed for optimal application. RNA interference (RNAi) is rapid, cheap and selective in complex biological systems and has created new insight sin fields of cancer research, genetic disorders, virology and drug design. Our knowledge about the role of miRNAs and siRNAs pathways in virus-host cell interactions in virus infected cells is incomplete. There are different viral diseases but few antiviral drugs are available. For example, acyclovir for herpes viruses, alpha-interferon for hepatitis C and B viruses and anti-retroviral for HIV are accessible. Also cancer is obviously an important target for siRNA-based therapies, but the main problem in cancer therapy is targeting metastatic cells which spread from the original tumor. There are also other possible reservations and problems that might delay or even hinder siRNA-based therapies for the treatment of certain conditions; however, this remains the most promising approach for a wide range of diseases. Clearly, more studies must be done to allow efficient delivery and better understanding of unwanted side effects of siRNA-based therapies. In this review miRNA and RNAi biology, experimental design, anti-viral and anti-cancer effects are discussed.

Systematic analysis of protein-detergent complexes applying dynamic light scattering to optimize solutions for crystallization trials

Detergents are widely used for the isolation and solubilization of membrane proteins to support crystallization and structure determination. Detergents are amphiphilic molecules that form micelles once the characteristic critical micelle concentration (CMC) is achieved and can solubilize membrane proteins by the formation of micelles around them. The results are presented of a study of micelle formation observed by in situ dynamic light-scattering (DLS) analyses performed on selected detergent solutions using a newly designed advanced hardware device. DLS was initially applied in situ to detergent samples with a total volume of approximately 2 µl. When measured with DLS, pure detergents show a monodisperse radial distribution in water at concentrations exceeding the CMC. A series of all-trans n-alkyl-β-D-maltopyranosides, from n-hexyl to n-tetradecyl, were used in the investigations. The results obtained verify that the application of DLS in situ is capable of distinguishing differences in the hydrodynamic radii of micelles formed by detergents differing in length by only a single CH2 group in their aliphatic tails. Subsequently, DLS was applied to investigate the distribution of hydrodynamic radii of membrane proteins and selected water-insoluble proteins in presence of detergent micelles. The results confirm that stable protein-detergent complexes were prepared for (i) bacteriorhodopsin and (ii) FetA in complex with a ligand as examples of transmembrane proteins. A fusion of maltose-binding protein and the Duck hepatitis B virus X protein was added to this investigation as an example of a non-membrane-associated protein with low water solubility. The increased solubility of this protein in the presence of detergent could be monitored, as well as the progress of proteolytic cleavage to separate the fusion partners. This study demonstrates the potential of in situ DLS to optimize solutions of protein-detergent complexes for crystallization applications.

Role of HBx and truncated HBx in HBV replication

As one of the principal causes of liver diseases, such as chronic hepatitis B, hepatic cirrhosis and hepatocellular carcinoma (HCC), hepatitis B virus (HBV) infection has been a major health problem worldwide. It is estimated that more than 500 million individuals have been infected with HBV worldwide and 1 million die of HBV infection-associated diseases annually. HBV X protein (HBx) is a multifunctional protein that can modulate various cellular processes and plays a crucial role in the pathogenesis of HCC. In recent years, the role of HBx in HBV replication has been more or less confirmed. In addition, more and more natural HBx truncated mutants and their roles in HBV replication have been found. This review aims to elucidate the roles of HBx and truncated HBx in HBV replication.

The role of hepatitis B virus X protein is related to its differential intracellular localization

Chronic hepatitis B virus (HBV) infection has been strongly associated with hepatocellular carcinoma. HBV encodes an oncogenic hepatitis B virus X protein (HBx), which is a multifunctional regulator that modulates signal transduction, transcription, cell cycle progress, protein degradation, apoptosis, and genetic stability through direct and indirect interaction with host factors. The subcellular localization of HBx is primarily cytoplasmic, with a small fraction in the nucleus. In addition, high levels of HBx expression lead to an abnormal mitochondrial distribution. The dynamic distribution of HBx could be important to the multiple functions of HBx at different stages of the HBV life cycle. This short review presents an overview of the differential roles of HBx as a function of its intracellular localization.

Does RNA interference provide new hope for control of chronic hepatitis B infection?

Hepatitis B virus (HBV) infection is a global human health problem, with an estimated 350 million people having chronic hepatitis B (CHB) infection worldwide. The majority of infections acquired during adulthood are resolved without intervention; however, infections acquired at birth or during early childhood have a 90% chance of progressing to CHB, leading to a host of adverse effects on the liver, including cirrhosis and cancer. CHB is currently treated with a combination of cytokines and/or nucleoside/nucleotide analogues; however, adverse side effects to cytokine therapy and the selection of resistance mutations to nucleoside analogues often abrogate the efficacy of treatment. The recent discovery that small interfering RNA and microRNA are active in mammalian cells suggests it might be possible to supplement existing HBV therapies with small RNA-based therapeutic(s).

High-level expression and large-scale preparation of soluble HBx antigen from Escherichia coli

The HBx (hepatitis B virus X protein) is a multifunctional regulator of cellular signal transduction and transcription pathways in host-infected cells. Evidence suggests that HBx has a critical role in the pathogenesis of hepatocellular carcinoma. However, the lack of efficient large-scale preparation methods for soluble HBx has hindered studies on the structure and function of HBx. Here, a new pMAL-c2x protein fusion and purification system was used for high-level expression of soluble HBx fusion protein. The high-purity fusion protein was obtained via amylose resin chromatography and Q-Sepharose chromatography. The untagged HBx was efficiently and rapidly purified by Sephadex G-75 chromatography after cleavage by Factor Xa at 23 degrees C. The purity of active HBx protein was >99% with a very stable secondary structure dominated by alpha-helix, beta-sheet and random structure. The purified HBx protein can be analysed to determine its crystal structure and function and its capabilities as an effective immunogen.