Balance of Power in Host-Virus Arms Races

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'One Health' for the people of Hong Kong and the world

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SiRNA and shRNA screens advance key understanding of host factors required for HIV-1 replication

A recent RNAi screen used a genome-wide shRNA library to search for cellular factors required for HIV-1 replication. This work complements three other siRNA-based screening studies and potentially opens the door to the discovery of factors that are important for HIV-1 replication in physiological host cells such as T lymphocytes. shRNA screens can be further improved, and they could promise to unravel new pathways and new facets of virus-cell interactions. © 2009 Kok et al; licensee BioMed Central Ltd.published_or_final_versio

An EBV microRNA targets DICE1 tumor suppressor gene

Poster Session 2: Host-Cell Interactions – Non-Coding RNA, Exosomes, and Epigenetics: no. 13.19MicroRNAs (miRNAs) play a critical role in post-transcriptional regulation of gene expression. Several herpesviruses have been shown to express viral miRNAs. Identification of the targets of these miRNAs might derive mechanistic insight into viral pathogenesis. We have previously demonstrated that Epstein-Barr virus (EBV)-encoded miR-BART5 targets p53-upregulated modulator of apoptosis (PUMA) in nasopharyngeal carcinoma (NPC) and this regulation is important for the EBV persistence and survival of EBV-infected cell survivals. In addition to the anti-apoptotic role of miR-BART5, other oncogenic activities of EBV miRNAs may also contribute to the development of lymphocytic or epithelial malignancies. In this study, we screened for potential targets of EBV miRNAs and found that EBV miR-BART3-5p potently suppressed the expression of DICE1 tumor suppressor in cultured cells. DICE1 is known …postprin

Mutagenesis and genome engineering of Epstein-Barr virus in cultured human cells by CRISPR/Cas9

The clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR associated protein 9 nuclease (Cas9) system is a powerful genome-editing tool for both chromosomal and extrachromosomal DNA. DNA viruses such as Epstein–Barr virus (EBV), which undergoes episomal replication in human cells, can be effectively edited by CRISPR/Cas9. We have demonstrated targeted editing of the EBV genome by CRISPR/Cas9 in several lines of EBV-infected cells. CRISPR/Cas9-based mutagenesis and genome engineering of EBV provides a new method for genetic analysis, which has some advantages over bacterial artificial chromosome-based recombineering. This approach might also prove useful in the cure of EBV infection. In this chapter, we use the knockout of the BART promoter as an example to detail the experimental procedures for construction of recombinant EBV in human cells.postprin

Human TRBP and PACT directly interact with each other and associate with dicer to facilitate the production of small interfering RNA

Mammalian Dicer interacts with double-stranded RNA-binding protein TRBP or PACT to mediate RNA interference and micro-RNA processing. TRBP and PACT are structurally related but exert opposite regulatory activities on PKR. It is not understood whether TRBP and PACT are simultaneously required for Dicer. Here we show that TRBP directly interacts with PACT in vitro and in mammalian cells. TRBP and PACT form a triple complex with Dicer and facilitate the production of small interfering RNA (siRNA) by Dicer. Knockdown of both TRBP and PACT in cultured cells leads to significant inhibition of gene silencing mediated by short hairpin RNA but not by siRNA, suggesting that TRBP and PACT function primarily at the step of siRNA production. Taken together, these findings indicate that human TRBP and PACT directly interact with each other and associate with Dicer to stimulate the cleavage of double-stranded or short hairpin RNA to siRNA. Our work significantly alters the current model for the assembly and function of the Dicer-containing complex that generates siRNA and micro-RNA in human. © 2007 by The American Society for Biochemistry and Molecular Biology, Inc.postprin

Adenoviral delivery of RNA decoys restores cellular proapoptotic protein PUMA expression by silencing Epstein-Barr virus-encoded miR-BART5 in nasopharyngeal carcinoma cells

Poster Session 1 - Vaccines and Anti-Viral Therapeutics: no. 3.17Epstein-Barr virus (EBV) encodes 48 mature microRNAs that play important roles in viral maintenance and promote host cell survival by regulating viral transcripts expression, inhibiting apoptosis or facilitating to evade cell immune surveillance. We have previously shown that EBV-encoded miR-BART5 targets and downregulates cellular pro-apoptotic protein p53-upregulated modulator of apoptosis (PUMA) to promote cellular survival of EBV-infected nasopharyngeal carcinoma (NPC) cells. Since compromising miR-BART5 might induce apoptosis of EBV-infected NPC cell, in this study we have established an adenoviral expression system to deliver anti-miR-BART5 decoys to NPC cells. The anti-miR-BART5 decoys comprised 6 tandem repeats of miR-BART5 binding sites and their expression was driven by EBVEBER2 promoter. They were designed to serve as a competitive inhibitor of miR-BART5 to reverse miR-BART5's inhibitory effects on PUMA in EBV-infected NPC cells. The RNA polymerase III-dependent EBER2 promoter is particularly strong in ...postprin

CRTC1 transcriptional coactivator is required for hepatitis B virus gene expression and replication

This journal suppl. entitled: Metabolism, Diet and Disease 2014: Cancer and metabolismConference Theme: Cancer and metabolismPoster Presentation: P31BACKGROUND: Chronic hepatitis B virus (HBV) infection occurs in over 400 million people worldwide, 15-40% of whom will terminally develop severe liver diseases including hepatocellular carcinoma. Although development of HCC is a multi-step process, high HBV DNA level is a major risk factor for disease progression. Transcription of HBV from the cccDNA template is essential for its replication and requires CREB transcription factor, a master regulator of cell metabolism. However, transcriptional coactivators that facilitate CREB-dependent activation of HBV transcription remain to be identified and characterized …published_or_final_versio

Roles of a novel splice variant of human IFI16 in innate immune response

Poster Presentation - Theme 4: Infection & immunityDNA from viral or bacterial pathogens activates innate immune response. The recognition of self-DNA would induce autoimmune diseases such as systemic lupus erythematosus (SLE). In human, AIM2 like receptors (ALRs) including AIM2, IFI16, IFIX and MNDA are DNA binding proteins implicated in DNA sensing. Most ALRs contain an N-terminal pyrin domain and C-terminal HIN200 domains. However, mouse SLE susceptibility locus p202 encodes only HIN200 domains. A human homolog of p202 was not found. Here, we identified and characterized a novel splice variant of human IFI16, which has a similar domain structure as mouse p202. We named it ...postprin