Article

γ-Herpesvirus Kinase Actively Initiates a DNA Damage Response by Inducing Phosphorylation of H2AX to Foster Viral Replication

Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA.
Cell host & microbe (Impact Factor: 12.33). 07/2007; 1(4):275-86. DOI: 10.1016/j.chom.2007.05.008
Source: PubMed

ABSTRACT

DNA virus infection can elicit the DNA damage response in host cells, including ATM kinase activation and H2AX phosphorylation. This is considered to be the host cell response to replicating viral DNA. In contrast, we show that during infection of macrophages murine gamma-herpesvirus 68 (gammaHV68) actively induces H2AX phosphorylation by expressing a viral kinase (orf36). GammaHV68-encoded orf36 kinase and its EBV homolog, BGLF4, induce H2AX phosphorylation independently of other viral genes. The process requires the kinase domain of Orf36 and is enhanced by ATM. Orf36 is important for gammaHV68 replication in infected animals, and orf36, H2AX, and ATM are all critical for efficient gammaHV68 replication in primary macrophages. Thus, activation of proximal components of the DNA damage signaling response is an active viral kinase-driven strategy required for efficient gamma-herpesvirus replication.

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Available from: Vera L Tarakanova
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    • "A comprehensive report of various stimuli of EBV in various cell lines indicates that strict dependence on ATM is stimulus-specific; ATM was vital for early steps in reactivation but not for viral DNA replication per se[44]. Furthermore , murine herpesvirus 68 required ATM and γH2AX in primary mouse macrophages only at low MOI, but neither are required for growth in MEFs regardless of MOI[45,46]. Karposi sarcoma virus depends on ATM, as shown by reduced establishment and latency of KSHV in the absence of ATM[47,48]. "
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    ABSTRACT: Background Herpes simplex virus type 1 (HSV-1) can establish both lytic and latent infections in humans. The phosphorylation of histone H2AX, a common marker of DNA damage, during lytic infection by HSV-1 is well established. However, the role(s) of H2AX phosphorylation in lytic infection remain unclear. Methods Following infection of human foreskin fibroblasts by HSV-1 or HSV-2, we assayed the phosphorylation of H2AX in the presence of inhibitors of transcription, translation, or viral DNA replication, or in the presence of inhibitors of ATM and ATR kinases (KU-55933 and VE-821, respectively). We also assayed viral replication in fibroblasts in the presence of the kinase inhibitors or siRNAs specific for ATM and ATR, as well as in cell lines deficient for either ATR or ATM. Results The expression of viral immediate-early and early proteins (including the viral DNA polymerase), but not viral DNA replication or late protein expression, were required for H2AX phosphorylation following HSV-1 infection. Inhibition of ATM kinase activity prevented HSV-stimulated H2AX phosphorylation but had only a minor effect on DNA replication and virus yield in HFF cells. These results differ from previous reports of a dramatic reduction in viral yield following chemical inhibition of ATM in oral keratinocytes or following infection of ATM−/− cells. Inhibition of the closely related kinase ATR (whether by chemical inhibitor or siRNA disruption) had no effect on H2AX phosphorylation and reduced viral DNA replication only moderately. During infection by HSV-2, H2AX phosphorylation was similarly dispensable but was dependent on both ATM activity and viral DNA replication. Conclusion H2AX phosphorylation represents a cell type-specific and virus type-specific host response to HSV infection with little impact on viral infection. Electronic supplementary material The online version of this article (doi:10.1186/s12985-016-0470-1) contains supplementary material, which is available to authorized users.
    Full-text · Article · Dec 2016 · Virology Journal
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    • "HSV infection of ATM-deficient cells failed to induce phosphorylation of a member of the MRN complex (Nbs1), Chk2, and p53 indicating that the DNA damage response requires activation of ATM in HSV infected cells (Lilley et al., 2005; Shirata et al., 2005). Interestingly, while ATM is not needed for replication of MHV68 in mouse fibroblasts, ATM is required for efficient replication of MHV68 in mouse macrophages (Tarakanova et al., 2007). Thus, while we did not observe a difference in VZV replication in fibroblasts lacking ATM, ATM might be important for VZV replication in other cell types. "
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    ABSTRACT: Mammalian cells activate DNA damage response pathways in response to virus infections. Activation of these pathways can enhance replication of many viruses, including herpesviruses. Activation of cellular ATM results in phosphorylation of H2AX and recruits proteins to sites of DNA damage. We found that varicella-zoster (VZV) infected cells had elevated levels of phosphorylated H2AX and phosphorylated ATM and that these levels increased in cells infected with VZV deleted for ORF61 or ORF63, but not deleted for ORF67. Expression of VZV ORF61, ORF62, or ORF63 alone did not result in phosphorylation of H2AX. While BGLF4, the Epstein-Barr virus homolog of VZV ORF47 protein kinase, phosphorylates H2AX and ATM, neither VZV ORF47 nor ORF66 protein kinase phosphorylated H2AX or ATM. Cells lacking ATM had no reduction in VZV replication. Thus, VZV induces phosphorylation of H2AX and ATM and this effect is associated with the presence of specific VZV genes in virus-infected cells.
    Preview · Article · Mar 2014 · Virology
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    • "A common feature of herpesviruses is their capacity to activate DDRs in infected cells (Shirata et al., 2005; Gaspar and Shenk, 2006; Koopal et al., 2007; Tarakanova et al., 2007; Nikitin et al., 2010). Although in some cases this is associated with lytic or productive infection, when the virus has a requirement for rapid replication of its genome prior to virion assembly, at least two gamma-herpesviruses (Kaposi’s Sarcoma associated herpes virus (KSHV, aka HHV8) and EBV) trigger DDRs during the establishment of a latent infection. "
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    ABSTRACT: Viruses that establish a persistent infection, involving intracellular latency, commonly stimulate cellular DNA synthesis and sometimes cell division early after infection. However, most cells of metazoans have evolved "fail-safe" responses that normally monitor unscheduled DNA synthesis and prevent cell proliferation when, for instance, cell proto-oncogenes are "activated" by mutation, amplification, or chromosomal rearrangements. These cell intrinsic defense mechanisms that reduce the risk of neoplasia and cancer are collectively called oncogenic stress responses (OSRs). Mechanisms include the activation of tumor suppressor genes and the so-called DNA damage response that together trigger pathways leading to cell cycle arrest (e.g., cell senescence) or complete elimination of cells (e.g., apoptosis). It is not surprising that viruses that can induce cellular DNA synthesis and cell division have the capacity to trigger OSR, nor is it surprising that these viruses have evolved countermeasures for inactivating or bypassing OSR. The main focus of this review is how the human tumor-associated Epstein-Barr virus manipulates the host polycomb group protein system to control - by epigenetic repression of transcription - key components of the OSR during the transformation of normal human B cells into permanent cell lines.
    Full-text · Article · Oct 2013 · Frontiers in Genetics
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