Project description:Genetic screens have transformed our ability to interrogate cellular factor requirements in infection, yet current approaches are limited in their sensitivity, biased towards early stages of infection and provide only simplistic phenotypic information which is often based on infected cell survival. Here, by engineering human cytomegalovirus to express sgRNA libraries directly from the viral genome, we developed a sensitive, versatile, viral centric approach that allows profiling of different stages along viral infection in a pooled format. Using this approach, which we termed VECOS (Virus Encoded CRISPR-based direct readOut Screening system), we identified hundreds of novel dependency and restriction factors and we quantified their direct effects on viral genome replication, viral particle secretion and infectiousness of secreted particles, providing a multi-dimensional perspective on viral-host interactions. These high resolution measurements reveal that perturbations that alter late stages in HCMV life cycle mostly regulate HCMV particle quality rather than quantity, defining correct virion assembly as a critical stage that is heavily reliant on viral-host interactions. Overall, VECOS facilitates systematic high resolution dissection of human proteins' role along the infection cycle, providing a roadmap for in-depth dissection of host–herpesvirus interactions.
Project description:Small RNA deep sequencing analysis was conducted on primary human fibroblasts infected with human cytomegalovirus (HCMV). HCMV-encoded miRNAs accumulated to ~20% of the total smRNA population at late stages of infection, and our analysis led to improvements in viral miRNA annotations and identification of novel HCMV miRNAs. Through crosslinking and immunoprecipitation of Argonaute-bound RNAs from infected cells, followed by high-throughput sequencing (Ago CLIP-seq), we obtained direct evidence for incorporation of all HCMV miRNAs into the endogenous host silencing machinery. Additionally, significant upregulation was observed during infection for a host miRNA cluster containing miR-96, miR-182 and miR-183. We also identified novel non-miRNA forms of virus-derived smRNAs, revealing greater complexity within the smRNA population during HCMV infection. High-throughput profiling of smRNAs, Ago1-, and Ago2-associated miRNAs from HCMV-infected fibroblast cells. Wild-type HCMV Towne (Genbank FJ616285.1) was used for these studies.
Project description:Human cytomegalovirus (HCMV) is an important pathogen with multiple immune evasion strategies, including virally facilitated degradation of host antiviral restriction factors. Here, we describe a multiplexed approach to discover proteins with innate immune function on the basis of active degradation by the proteasome or lysosome during early phase HCMV infection. Using three orthogonal proteomic/transcriptomic screens to quantify protein degradation, with high confidence we identified 35 proteins enriched in antiviral restriction factors. A final screen employed a comprehensive panel of viral mutants to predict viral genes that target >250 human proteins. This approach revealed Helicase-like Transcription Factor (HLTF), a DNA helicase important in DNA repair, potently inhibits early viral gene expression but is rapidly degraded during infection. The functionally unknown HCMV protein UL145 facilitates HLTF degradation by recruiting the Cullin4 E3 ligase complex. Our approach and data will enable further identifications of innate pathways targeted by HCMV and other viruses.
Project description:Small RNA deep sequencing analysis was conducted on primary human fibroblasts infected with human cytomegalovirus (HCMV). HCMV-encoded miRNAs accumulated to ~20% of the total smRNA population at late stages of infection, and our analysis led to improvements in viral miRNA annotations and identification of novel HCMV miRNAs. Through crosslinking and immunoprecipitation of Argonaute-bound RNAs from infected cells, followed by high-throughput sequencing (Ago CLIP-seq), we obtained direct evidence for incorporation of all HCMV miRNAs into the endogenous host silencing machinery. Additionally, significant upregulation was observed during infection for a host miRNA cluster containing miR-96, miR-182 and miR-183. We also identified novel non-miRNA forms of virus-derived smRNAs, revealing greater complexity within the smRNA population during HCMV infection.
Project description:Identifying the spectrum of genes required for cancer cell survival can reveal essential cancer circuitry and therapeutic targets, but such a map remains incomplete for many cancer types. We apply genome-scale CRISPR-Cas9 loss-of-function screens to map the landscape of selectively essential genes in chordoma, a bone cancer with few validated targets. This approach confirms a known chordoma dependency, TBXT (T; brachyury), and identifies a range of additional dependencies, including PTPN11, ADAR, PRKRA, LUC7L2, SRRM2, SLC2A1, SLC7A5, FANCM, and THAP1. CDK6, SOX9, and EGFR, genes previously implicated in chordoma biology, are also recovered. We find genomic and transcriptomic features that predict specific dependencies, including interferon-stimulated gene expression, which correlates with ADAR dependence and is elevated in chordoma. Validating the therapeutic relevance of dependencies, small-molecule inhibitors of SHP2, encoded by PTPN11, have potent preclinical efficacy against chordoma. Our results generate an emerging map of chordoma dependencies to enable biological and therapeutic hypotheses.
Project description:Human cytomegalovirus (HCMV) is a major human pathogen whose life-long persistence is enabled by its remarkable capacity to systematically subvert host immune defences. In exploring the finding that HCMV infection upregulates tumor necrosis factor receptor 2 (TNFR2), a ligand for the proinflammatory anti-viral cytokine TNFa, we discovered the underlying mechanism was due to targeting of the protease, A Disintegrin And Metalloproteinase 17 (ADAM17). ADAM17 is the prototype ‘sheddase, a family of proteases that cleaves other membrane-bound proteins to release biologically active ectodomains into the supernatant. HCMV impaired ADAM17 surface expression through the action of two virally-encoded proteins in its UL/b’ region, UL148 and UL148D. Proteomic plasma membrane profiling of cells infected with a HCMV double deletion mutant for UL148 and UL148D with restored ADAM17 expression, combined with ADAM17 functional blockade, showed that HCMV stabilized the surface expression of 114 proteins (p<0.05) in an ADAM17-dependent fashion. These included known substrates of ADAM17 with established immunological functions such as TNFR2 and Jagged1, but also numerous novel host and viral targets, such as Nectin1, UL8 and UL144. Regulation of TNFa-induced cytokine responses and NK inhibition during HCMV infection were dependent on this impairment of ADAM17. We therefore identify a viral immunoregulatory mechanism in which targeting a single sheddase enables broad regulation of multiple critical surface receptors, revealing a paradigm for viral-encoded immunomodulation.
Project description:Porcine cytomegalovirus (PCMV; genus Cytomegalovirus, subfamily Betaherpesvirinae, family Herpesviridae) is an immunosuppressive virus that mainly inhibits the immune function of T lymphocytes and macrophages, which has caused great distress to the farming industry. In this study, we obtained the miRNA expression profiles of PCMV-infected and control porcine macrophages, PCMV-infected and control porcine tissues via high-throughput sequencing. The comprehensive analysis of miRNA profiles showed that 306 miRNA database annotated and 295 novel pig-encoded miRNAs were detected. Gene Ontology (GO) analysis of the target genes of miRNAs in PCMV infected porcine macrophages showed that the differentially expressed miRNAs are mainly involved in immune and metabolic process. This is the first report of the miRNA transcriptome in PCMV infected porcine macrophages and PCMV infected tissues and the analysis of the miRNA regulatory mechanism during PCMV infection. Further research into the regulatory mechanisms of miRNAs during immunosuppressive viral infections will contribute to the treatment and prevention of immunosuppressive viruses. miRNA expression profiling of PCMV-infected and control porcine macrophages; PCMV-infected and control porcine tissues via high-throughput sequencing.
Project description:More than half the world's population is infected with Human Cytomegalovirus (HCMV), increasing risks for the immuno-compromised, and causing significant congenital birth defects. The HCMV genome encodes >170 proteins; many that remain uncharacterised, which restricts development opportunities for new antivirals. In this study, a molecular assay was developed to conduct a genome-wide HCMV screen to identify genes that function during late stages of infection. Saliently, loss of UL49 completely abolished production of infectious virions. During infection, UL49 displayed leaky late expression kinetics and nuclear localization. Functionally, UL49 is as an essential subunit of the viral pre-initiation complex (vPIC), enhancing transcription of late viral genes containing non-canonical TATT motif promoters. RNA-seq revealed the full repertoire of vPIC-regulated genes, including transcripts coding for capsid subunits, envelope glycoproteins and egress-associated tegument proteins. Therefore, UL49 together with other vPIC subunits, serve as fundamental HCMV effectors that govern successful completion of the replication cycle.