PMID- 31118254 OWN - NLM STAT- MEDLINE DCOM- 20200601 LR - 20211204 IS - 1098-5514 (Electronic) IS - 0022-538X (Print) IS - 0022-538X (Linking) VI - 93 IP - 15 DP - 2019 Aug 1 TI - mTOR Dysregulation by Vaccinia Virus F17 Controls Multiple Processes with Varying Roles in Infection. LID - 10.1128/JVI.00784-19 [doi] LID - e00784-19 AB - Despite producing enormous amounts of cytoplasmic DNA, poxviruses continue to replicate efficiently by deploying an armory of proteins that counter host antiviral responses at multiple levels. Among these, poxvirus protein F17 dysregulates the host kinase mammalian target of rapamycin (mTOR) to prevent the activation of stimulator of interferon genes (STING) expression and impair the production of interferon-stimulated genes (ISGs). However, the host DNA sensor(s) involved and their impact on infection in the absence of F17 remain unknown. Here, we show that cyclic-di-GMP-AMP (cGAMP) synthase (cGAS) is the primary sensor that mediates interferon response factor (IRF) activation and ISG responses to vaccinia virus lacking F17 in both macrophages and lung fibroblasts, although additional sensors also operate in the latter cell type. Despite this, ablation of ISG responses through cGAS or STING knockout did not rescue defects in late-viral-protein production, and the experimental data pointed to other functions of mTOR in this regard. mTOR adjusts both autophagic and protein-synthetic processes to cellular demands. No significant differences in autophagic responses to wild-type or F17 mutant viruses could be detected, with autophagic activity differing across cell types or states and exhibiting no correlations with defects in viral-protein accumulation. In contrast, results using transformed cells or altered growth conditions suggested that late-stage defects in protein accumulation reflect failure of the F17 mutant to deregulate mTOR and stimulate protein production. Finally, rescue approaches suggest that phosphorylation may partition F17's functions as a structural protein and mTOR regulator. Our findings reveal the complex multifunctionality of F17 during infection.IMPORTANCE Poxviruses are large, double-stranded DNA viruses that replicate entirely in the cytoplasm, an unusual act that activates pathogen sensors and innate antiviral responses. In order to replicate, poxviruses therefore encode a wide range of innate immune antagonists that include F17, a protein that dysregulates the kinase mammalian target of rapamycin (mTOR) to suppress interferon-stimulated gene (ISG) responses. However, the host sensor(s) that detects infection in the absence of F17 and its precise contribution to infection remains unknown. Here, we show that the cytosolic DNA sensor cGAS is primarily responsible for activating ISG responses in biologically relevant cell types infected with a poxvirus that does not express F17. However, in line with their expression of approximately 100 proteins that act as immune response and ISG antagonists, while F17 helps suppress cGAS-mediated responses, we find that a critical function of its mTOR dysregulation activity is to enhance poxvirus protein production. CI - Copyright (c) 2019 American Society for Microbiology. FAU - Meade, Nathan AU - Meade N AD - Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA. FAU - King, Melvin AU - King M AD - Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, New York, USA. FAU - Munger, Joshua AU - Munger J AD - Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, New York, USA. FAU - Walsh, Derek AU - Walsh D AD - Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA derek.walsh@northwestern.edu. LA - eng GR - R01 AI127370/AI/NIAID NIH HHS/United States GR - R01 AI127456/AI/NIAID NIH HHS/United States GR - R21 AI105330/AI/NIAID NIH HHS/United States PT - Journal Article PT - Research Support, N.I.H., Extramural PT - Research Support, Non-U.S. Gov't DEP - 20190717 PL - United States TA - J Virol JT - Journal of virology JID - 0113724 RN - 0 (Viral Structural Proteins) RN - EC 2.7.11.1 (TOR Serine-Threonine Kinases) SB - IM MH - Animals MH - Autophagy MH - Cell Line MH - Chlorocebus aethiops MH - *Down-Regulation MH - Fibroblasts/immunology/virology MH - *Host Microbial Interactions MH - Humans MH - Immune Evasion MH - Macrophages/immunology/virology MH - TOR Serine-Threonine Kinases/*metabolism MH - Vaccinia virus/*growth & development MH - Viral Structural Proteins/*metabolism MH - *Virus Replication PMC - PMC6639273 OTO - NOTNLM OT - F17 OT - cGAS OT - interferon-stimulated gene OT - mTOR OT - poxvirus OT - protein synthesis OT - vaccinia virus EDAT- 2019/05/24 06:00 MHDA- 2020/06/02 06:00 PMCR- 2020/01/17 CRDT- 2019/05/24 06:00 PHST- 2019/05/14 00:00 [received] PHST- 2019/05/14 00:00 [accepted] PHST- 2019/05/24 06:00 [pubmed] PHST- 2020/06/02 06:00 [medline] PHST- 2019/05/24 06:00 [entrez] PHST- 2020/01/17 00:00 [pmc-release] AID - JVI.00784-19 [pii] AID - 00784-19 [pii] AID - 10.1128/JVI.00784-19 [doi] PST - epublish SO - J Virol. 2019 Jul 17;93(15):e00784-19. doi: 10.1128/JVI.00784-19. Print 2019 Aug 1.