Coordinate Regulation of DNA Damage and Type I Interferon Responses Imposes an Antiviral State That Attenuates Mouse Gammaherpesvirus Type 68 Replication in Primary Macrophages

Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
Journal of Virology (Impact Factor: 4.44). 04/2012; 86(12):6899-912. DOI: 10.1128/JVI.07119-11
Source: PubMed


DNA damage response (DDR) is a sophisticated cellular network that detects and repairs DNA breaks. Viruses are known to activate
the DDR and usurp certain DDR components to facilitate replication. Intriguingly, viruses also inhibit several DDR proteins,
suggesting that this cellular network has both proviral and antiviral features, with the nature of the latter still poorly
understood. In this study we show that irradiation of primary murine macrophages was associated with enhanced expression of
several antiviral interferon (IFN)-stimulated genes (ISGs). ISG induction in irradiated macrophages was dependent on type
I IFN signaling, a functional DNA damage sensor complex, and ataxia-telangiectasia mutated kinase. Furthermore, IFN regulatory
factor 1 was also required for the optimal expression of antiviral ISGs in irradiated macrophages. Importantly, DDR-mediated
activation of type I IFN signaling contributed to increased resistance to mouse gammaherpesvirus 68 replication, suggesting
that the coordinate regulation of DDR and type I IFN signaling may have evolved as a component of the innate immune response
to virus infections.

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Available from: Vera L Tarakanova
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    • "Overall, these results reinforce the non-random ATR activation by ASFV, both in non-replicating and replicating susceptible mammalian cells. The specific ATR activation has also been described for other DNA viruses (Li and Hayward, 2011; Weitzman et al., 2010), and several lines of evidence have suggested that HR facilitates infectivity by recognizing viral DNA as genomic DSBs, thus enhancing the access to the host DNA replication and repair machinery, subverting host proteins and modulating host immune responses (Mboko et al., 2012; Nikitin and Luftig, 2012). Interestingly, the foreseen possibility of interfering with the ASFV infection using PI3K inhibitors (able to target ATR) open new insights of future antiviral strategies (Cuesta-Geijo et al., 2012; Simões et al., 2013). "
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    ABSTRACT: Although African swine fever virus (ASFV) replicates in viral cytoplasmic factories, the presence of viral DNA within the host cell nucleus has been previously reported to be essential for productive infection. Herein, we described, for the first time, the intranuclear distribution patterns of viral DNA replication events, preceding those that occur in the cytoplasmic compartment. Using BrdU pulse-labelling experiments, newly synthesized ASFV genomes were exclusively detected inside the host cell nucleus at the early phase of infection, both in swine monocyte-derived macrophages (MDMs) and Vero cells. From 8hpi onwards, BrdU labelling was only observed in ASFV cytoplasmic factories. Our results also show that ASFV specifically activates the Ataxia Telangiectasia Mutated Rad-3 related (ATR) pathway in ASFV-infected swine MDMs from the early phase of infection, most probably because ASFV genome is recognized as foreign DNA. Morphological changes of promyelocytic leukaemia nuclear bodies (PML-NBs), nuclear speckles and Cajal bodies were also found in ASFV-infected swine MDMs, strongly suggesting the viral modulation of cellular antiviral responses and cellular transcription, respectively. As described for other viral infections, the nuclear reorganization that takes place during ASFV infection may also provide an environment that favours its intranuclear replication events. Altogether, our results contribute for a better understanding of ASFV replication strategies, starting with an essential intranuclear DNA replication phase which induces host nucleus changes towards a successful viral infection. Copyright © 2015. Published by Elsevier B.V.
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    • "Activation of IFN signaling is described in syndromes characterized by defects in enzymes processing/ eliminating cytoplasmic DNA (Barber, 2011b; Stetson et al., 2008). Furthermore, genotoxic drug-induced cellular senescence correlates with production of IFN and induction of IFNstimulated genes (Fridman and Tainsky, 2008; Mboko et al., 2012; Novakova et al., 2010). "
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    ABSTRACT: Expression of type I interferons (IFNs) can be induced by DNA-damaging agents, but the mechanisms and significance of this regulation are not completely understood. We found that the transcription factor IRF3, activated in an ATM-IKKα/β-dependent manner, stimulates cell-autonomous IFN-β expression in response to double-stranded DNA breaks. Cells and tissues with accumulating DNA damage produce endogenous IFN-β and stimulate IFN signaling in vitro and in vivo. In turn, IFN acts to amplify DNA-damage responses, activate the p53 pathway, promote senescence, and inhibit stem cell function in response to telomere shortening. Inactivation of the IFN pathway abrogates the development of diverse progeric phenotypes and extends the lifespan of Terc knockout mice. These data identify DNA-damage-response-induced IFN signaling as a critical mechanism that links accumulating DNA damage with senescence and premature aging. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.
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    • "In fact, we detected high levels of ROS at 5 h postnucleofection (data not shown). In addition, it was recently described that macrophages exposed to g-radiation concomitant with DDR activation undergo a type I IFN response indicating crosstalk between these two pathways (Mboko et al., 2012). However, how IFN is connected with DDR is not understood. "
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    ABSTRACT: The interferon (IFN) response, induced as a side effect after transfection of nucleic acids into mammalian cells, is known but inadequately described. We followed the IFN response, the fate of cells, and the possible mechanisms leading to this response in NIH3T3 mouse fibroblasts after DNA nucleofection. The gateway destination vector, phGf, and its derivatives encoding toxic and non-toxic variants of the minor structural proteins of polyomaviruses, VP2 and VP3, were used. DNA vector sequences induced in cells the production of high levels of IFN and the upregulation of the IFN-inducible genes, Mx-1, STAT1, IRF1, and IRF7. The IFN response was not restricted to phGf-derived plasmids. In nucleofected cells, upregulation of the modified γ-histone 2A.X indicating DNA damage and inhibition of cell proliferation were also observed. Although 3T3 cells expressed the Toll-like receptor-9 (TLR9) and vectors used for nucleofection contained unmethylated CpGs, signaling leading to IFN induction was found to be TLR9 independent. However, the early activation of nuclear factor-kappa B suggested the participation of this transcription factor in IFN induction. Surprisingly, in contrast to nucleofection, transfection using a cationic polymer induced only a poor IFN response. Together, the results point to a strong side effect of nucleofection.
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