Interferon-γ (IFN-γ) represents one of the most important innate immunity responses in a host to combat infections of many human viruses including human herpesviruses. Human N-myc interactor (Nmi) protein, which has been shown to interact with signal transducer and activator of transcription (STAT) proteins including STAT1, is important for the activation of IFN-γ induced STAT1-dependent transcription of many genes responsible for IFN-γ immune responses. However, no proteins encoded by herpesviruses have been reported to interact with Nmi and inhibit Nmi-mediated activation of IFN-γ immune responses to achieve immune evasion from IFN-γ responses. In this study, we show strong evidence that the UL23 protein of human cytomegalovirus (HCMV), a human herpesvirus, specifically interacts with Nmi. This interaction was identified through a yeast two-hybrid screen and co-immunoprecipitation in human cells. We observed that Nmi, when bound to UL23, was not associated with STAT1, suggesting that UL23 binding of Nmi disrupts the interaction of Nmi with STAT1. In cells overexpressing UL23, we observed (a) significantly reduced levels of Nmi and STAT1 in the nuclei, the sites where these proteins act to induce transcription of IFN-γ stimulated genes, and (b) decreased levels of the induction of the transcription of IFN-γ stimulated genes. UL23-deficient HCMV mutants induced higher transcription of IFN-γ stimulated genes and exhibited lower titers than parental and control revertant viruses expressing functional UL23 in IFN-γ treated cells. Thus, UL23 appears to interact directly with Nmi and inhibit nuclear translocation of Nmi and its associated protein STAT1, leading to a decrease of IFN-γ induced responses and an increase of viral resistance to IFN-γ. Our results further highlight the roles of UL23-Nmi interactions in facilitating viral immune escape from IFN-γ responses and enhancing viral resistance to IFN antiviral effects.
a b s t r a c tAberrant expression of miR-204 had been frequently reported in cancer studies; however, the mechanism of its function in retinoblastoma remained unknown. Here, we reported that miR-204 was frequently downregulated in retinoblastoma tissues and cell lines. Enforced expression of miR-204 inhibited retinoblastoma cells' proliferation and invasion. In vivo study indicated that restoration of miR-204 inhibited tumor growth. CyclinD2 and MMP-9 were identified as potential targets of miR-204. In addition, a reverse correlation between miR-204 and CyclinD2 or MMP-9 expression was noted in retinoblastoma tissues. Taken together, our results identified a crucial tumor suppressive role of miR-204 in the progression of retinoblastoma.
Background
Severe acute respiratory syndrome coronavirus clade 2 (SARS‐CoV‐2) is a single‐stranded RNA virus responsible for the global pandemic of the coronavirus disease‐2019 (COVID‐19). To date, there are still no effective approaches for the prevention and treatment of COVID‐19.
Objective
The present study aims to explore the possible mechanisms of SARS‐CoV‐2 infection in human lung cells.
Methods
Data interpretation was conducted by recruiting bioinformatics analysis, including Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathways analysis using downloaded data from the NCBI Gene Expression Omnibus database.
Results
The present study demonstrated that SARS‐CoV‐2 infection induces the upregulation of 14 interferon‐stimulated genes, indicative of immune, and interferon responses to the virus. Notably, genes for pyrimidine metabolism and steroid hormone biosynthesis are selectively enriched in human lung cells after SARS‐CoV‐2 infection, suggesting that altered pyrimidine metabolism and steroid biosynthesis are remarkable, and perhaps druggable features after SARS‐CoV‐2 infection. Besides, there is a strong positive correlation between viral ORF1ab, ORF6, and angiotensin‐converting enzyme 2 (ACE2) expression in human lung cells, implying that ACE2 facilitates SARS‐CoV‐2 infection and replication in host cells probably through the induction of ORF1ab and ORF6.
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