Marek's Disease Virus Disables the ATR-Chk1 Pathway by Activating STAT3

Abstract

Oncogenic virus replication often leads to genomic instability, causing DNA damage and inducing the DNA damage response (DDR) pathway. The DDR pathway is a cellular pathway that senses DNA damage and regulates the cell cycle to maintain genomic stability. Therefore, the DDR pathway is critical for the viral lifecycle and tumorigenesis. Marek’s disease virus (MDV), an alphaherpesvirus that causes lymphoma in chickens, has been shown to induce DNA damage in infected cells. However, the interaction between MDV and the host DDR is unclear. In this study, we observed that MDV infection causes DNA strand breakage in chicken fibroblast (CEF) cells along with an increase in the DNA damage markers p53 and p21. Interestingly, we showed that phosphorylation of STAT3 was increased during MDV infection, concomitantly with a decrease of Chk1 phosphorylation. In addition, we found that MDV infection was enhanced by VE-821, an ATR-specific inhibitor, but attenuated by hydroxyurea, an ATR activator. Moreover, inhibition of STAT3 phosphorylation by Stattic eliminates the ability of MDV to inhibit Chk1 phosphorylation. Finally, we showed that MDV replication was decreased by Stattic treatment. Taken together, these results suggest that MDV disables the ATR-Chk1 pathway through STAT3 activation to benefit its replication. IMPORTANCE MDV is used as a biomedical model to study virus-induced lymphoma due to the similar genomic structures and physiological characteristics of MDV and human herpesviruses. Upon infection, MDV induces DNA damage, which may activate the DDR pathway. The DDR pathway has a dual impact on viruses because it manipulates repair and recombination factors to facilitate viral replication and also initiates antiviral action by regulating other signaling pathways. Many DNA viruses evolve to manipulate the DDR pathway to promote virus replication. In this study, we identified a mechanism used by MDV to inhibit ATR-Chk1 pathways. ATR is a cellular kinase that responds to broken single-stranded DNA, which has been less studied in MDV infection. Our results suggest that MDV infection activates STAT3 to disable the ATR-Chk1 pathway, which is conducive to viral replication. This finding provides new insight into the role of STAT3 in interrupting the ATR-Chk1 pathway during MDV replication.

Antiviral drug screen identifies DNA-damage response inhibitor as potent blocker of SARS-CoV-2 replication

“…It is known that many viruses hijack that pathway for efficient replication (Boichuk et al, 2010;Lilley et al, 2007), and that pathway is also modulated by DNA tumor viruses (Pancholi et al, 2017). For example, alphaherpesvirus and BK polyomavirus (BKPyV) have been shown to induce the DDR pathway during infection (Lian et al, 2019;Verhalen et al, 2015). It is apparent that many RNA viruses can induce significant DNA damage, even in cases in which viral replication takes place exclusively in the cytoplasm (Ryan et al, 2016;Nguyen et al, 2018).…”

Pseudorabies virus kinase UL13 phosphorylates H2AX to foster viral replication

“…Besides a traditional interferon response, cellular DDRs have also emerged as part of the cells' anti‐viral arsenal. Therefore, many viruses have evolved tactics to either activate or circumvent the host DDR pathway to facilitate their replication 25,26 27,28 .…”

“…Therefore, many viruses have evolved tactics to either activate or circumvent the host DDR pathway to facilitate their replication. 25,26 Viruses mainly activate DDR either through sensing a viral genome or aberrant DNA structure, or by viral proteins implicated in replication, transcription, and cell cycle regulation. 27,28 For example, HSV recruits γH2AX and mediator of DNA damage checkpoint 1 (MDC1) at the site of viral DNA synthesis within hours post-infection.…”

HDAC6 Triggers the ATM-Dependent DNA Damage Response To Promote PRV Replication

“…After the virus infects the host cell, the cell provides the material basis for DNA replication, transcription, and RNA processing of the virus and also provides conditions for the integration of viral DNA into its chromosomes to establish lysogenic infection and regulate the expression of viral genes ( 35 ). Viral infection induces DDR through different mechanisms, and viruses have also evolved different mechanisms to counter the host cell's DDR ( 31 , 36 – 38 ). There is a complex relationship between virus and DDR.…”