Project description:To deal with the broad spectrum of coronaviruses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), that threatens human health, it is essential to develop not only drugs that target viral proteins but also consider drugs that target host proteins/cellular processes to protect them from being hijacked for viral infection and replication. To this end, it has been reported that autophagy is deeply involved in coronavirus infection. In this study, we used airway organoids to screen a chemical library of autophagic modulators to identify compounds that could potentially be used to fight against infections by a broad range of coronaviruses. Among the 80 autophagy-related compounds tested, cycloheximide and thapsigargin reduced SARS-CoV-2 infection efficiency in a dose-dependent manner. Cycloheximide treatment reduced the infection efficiency of not only six SARS-CoV-2 variants but also human coronavirus (HCoV)-229E and HCoV-OC43. Cycloheximide treatment also reversed viral infection-induced innate immune responses. However, even low dose (1 μM) cycloheximide treatment altered the expression profile of ribosomal RNAs, thus side effects such as inhibition of protein synthesis in host cells must be considered. These results suggest that cycloheximide has broad-spectrum anti-coronavirus activity in vitro and warrants further investigation.
Project description:Initially identified as a functional marker for resident-memory (Trm) CD8+ T cells, CD103 (encoded by ITGAE gene) has broad roles in immunity and diseases. Elucidating the function and regulation of CD103 is thus of importance. This study revealed that the CD103 expression by CD8 T cells under steady state contributes to the clearance of acute viral infection. More importantly, it discovered TGF-SKI-Smad4 a critical signaling axis in restricting CD103 expression in CD8+ T cells for their function. Mechanistically, by ChIP-Seq and ChIP analysis, SKI associated with Smad4 was found to directly and epigenetically suppress CD103 transcription. This study therefore reveals a novel TGF-SKI-Smad4 pathway to specifically enable CD103 expression in CD8+ T cells for protective immunity.
Project description:Among the flaviviral proteins, NS5 is the largest and most conserved. NS5 contains major enzymatic components of the viral replication complex. Disruption of the common key NS5-host protein-protein interactions critical for viral replication could aid in the development of broad-spectrum anti-flaviviral therapeutics. To this end, we investigated the JEV- and ZIKV-NS5 interactomes in human cells using GFP pull-downs with mass spectrometry analysis in a label-free fashion. A total of 138 cellular proteins interacting with NS5 from JEV, ZIKV, or both were identified as Protein classification analysis of identified cellular targets revealed the enrichment of RNA binding, processing and splicing including spliceosomal and spliceosome-associated proteins in both datasets. Comparison of our data with literature not only revealed several cellular NS5 interacting proteins shared among flaviviruses, but also identified proteins that have no known function in flavivirus biology such as RNA polymerase II-associated Paf1 complex, protein phosphatase 6, and s-adenosylmethionine synthetase. Our study generates the first landscape of the JEV and ZIKV NS5 interactome in human cells and identifies cellular proteins that are potentially targetable for broad-spectrum anti-flaviviral therapy.
Project description:RNA interference (RNAi) functions as the major host antiviral defense in insects, while less is understood about how to utilize antiviral RNAi in controlling viral infection in insects. Enoxacin belongs to the family of synthetic antibacterial compounds based on a fluoroquinolone skeleton that has been previously found to enhance RNAi in mammalian cells. In this study, we showed that enoxacin efficiently inhibited viral replication of Drosophila C virus (DCV) and Cricket paralysis virus (CrPV) in cultured Drosophila cells. Enoxacin promoted the loading of Dicer-2-processed virus-derived siRNA into the RNA-induced silencing complex, thereby enhancing antiviral RNAi response in infected cells. Moreover, enoxacin treatment elicited an RNAi-dependent in vivo protective efficacy against DCV or CrPV challenge in adult fruit flies. In addition, enoxacin also inhibited replication of flaviviruses, including Dengue virus and Zika virus, in Aedes mosquito cells in an RNAi-dependent manner. Together, our findings demonstrated that enoxacin can enhance RNAi in insects, and enhancing RNAi by enoxacin is an effective antiviral strategy against diverse viruses in insects, which may be exploited as a broad-spectrum antiviral agent to control vector transmission of arboviruses or viral diseases in insect farming.
Project description:There is a growing need for novel antiviral therapies that are broad-spectrum, effective, and not subject to resistance due to viral mutations. Using high-throughput screening methods, including computational docking studies and an ISG54-luciferase reporter assay, we identified a class of isoflavone compounds that act as specific agonists of innate immune signaling pathways and cause activation of the IRF-3 transcription factor. The objective of the microarray study was to examine the biological pathways associated with global gene expression changes following agonist treatment.
Project description:Cytoplasmic degradation of eukaryotic mRNAs in 3’ to 5’ direction is catalyzed by the exosome complex together with the Ski complex and, in the yeast Saccharomyces cerevisiae, the Ski7 protein. This exosome-Ski-system also degrades ribosome-associated aberrant mRNAs lacking a stop codon, a pathway called non-stop-mRNA decay (NSD). However, the interplay between the Ski components and the ribosome is unknown. Here, we report that the Ski complex can associate with ribosomes in vitro and in vivo independently of Ski7. Ribosome profiling suggests that this association is important for NSD but also for general mRNA turnover. A cryo-electron microscopy structure reveals that the Ski complex binds near the mRNA entry site of the 40S subunit, facilitating the threading of the mRNA into the Ski2 helicase. Collectively, these results demonstrate an unanticipated role for the Ski complex in mRNA decay of ribosome-associated mRNAs, mediated by a direct interaction with the translation machinery.
Project description:Classical antiviral therapy inhibit viral proteins and are subject to resistance. To counteract this emergence, alternative strategy has been developed that target cellular factors. We hypothesized that such approach could also be useful to identify broad antivirals. Influenza A virus was used as a model for viral diversity and need for therapy against unpredictable viruses as recently underlined by the H1N1 pandemic. We proposed to identify a gene-expression signature associated with infection with different influenza A virus subtypes which could help to identify potential antiviral drugs with broad spectrum. Cellular gene expression response to infection with five different human and avian influenza viruses strains was analyzed and 300 genes were determined as differentially expressed between infected and non-infected samples. Strikingly, only a few genes were induced by infection and related to immune response. A more concise list was used to screen connectivity map, a database of drug-associated gene expression profiles, for molecules with inverse profiles than the signature of infection. We hypothesized that such compounds would induce an unfavorable cellular environment for influenza virus replication. Eight potential antivirals including ribavirin were identified, and six inhibited influenza viral growth in vitro. The new pandemic H1N1 virus, which was not used to define the gene expression signature of infection, was inhibited by five of the eight identified molecules, demonstrating that this strategy could help to identify broad spectrum antivirals. This is the first study showing that a gene expression based-screening can be used to identify antivirals. Such approaches could accelerate the drug discovery progress and could be extended to other pathogens. A549 (human lung epithelial cells) were infected with 5 different influenza A strains (A/New Caledonia/20/99 (H1N1), A/Moscow/10/99 (H3N2), A/Lyon/969/09 (H1N1 SOI-V), A/Turkey/582/2006 (H5N1), A/Finch/England/2051/94 (H5N2), and A/Chicken/Italy/2076/99 (H7N1)) or mock infected. Five independant replicates were done and hybridized on a different microarray. The overall design is thus composed of 5 mock samples, and 5x5 infected samples.
Project description:Delineating key HSC regulators is of significant interest for informing the treatment of hematologic malignancy. While HSC activity is enhanced by overexpression of SKI, the transforming growth factor-beta (TGFβ) signaling antagonist corepressor, its requirement in HSC is unknown. Here we reveal a profound defect in Ski-/- HSC fitness but not specification. Transcriptionally, Ski-/- HSC exhibited striking upregulation of TGFb superfamily signaling and splicing alterations. As these are both common aspects of myelodysplastic-syndrome (MDS) pathobiology with prognostic value, we investigated the role of SKI in MDS. A SKI-correlated gene signature defines a subset of low-risk MDS patients with active TGFβ signaling and deregulated RNA splicing (e.g. CSF3R). The apparent paradox of Ski-/- HSC sharing molecular aspects of MDS with elevated SKI-mRNA is resolved by miR-21 targeting of SKI in MDS. We conclude that miR-21-mediated loss of SKI contributes to early stage MDS pathogenesis by activating TGFβ signaling and alternative splicing while hindering HSC fitness.