Induction of a Cellular DNA Damage Response by Porcine Circovirus Type 2 Facilitates Viral Replication and Mediates Apoptotic Responses.

Li Wei,Yi Yang,Shanshan Zhu,Rong Quan,Jing Wang,Xu Yan,Zixue Li,Jue Liu,Lei Hou,Haijun Jiang,Naidong Wang

doi:10.1038/srep39444

Abstract

Cellular DNA damage response (DDR) triggered by infection of DNA viruses mediate cell cycle checkpoint activation, DNA repair, or apoptosis induction. In the present study, infection of porcine circovirus type 2 (PCV2), which serves as a major etiological agent of PCV2-associated diseases (PCVAD), was found to elicit a DNA damage response (DDR) as observed by the phosphorylation of H2AX and RPA32 following infection. The response requires active viral replication, and all the ATM (ataxia telangiectasia-mutated kinase), ATR (ATM- and Rad3-related kinase), and DNA-PK (DNA-dependent protein kinase) are the transducers of the DDR signaling events in the PCV2-infected cells as demonstrated by the phosphorylation of ATM, ATR, and DNA-PK signalings as well as reductions in their activations after treatment with specific kinase inhibitors. Inhibitions of ATM, ATR, and DNA-PK activations block viral replication and prevent apoptotic responses as observed by decreases in cleaved poly-ADP ribose polymerase (PARP) and caspase-3 as well as fragmented DNA following PCV2 infection. These results reveal that PCV2 is able to exploit the cellular DNA damage response machinery for its own efficient replication and for apoptosis induction, further extending our understanding for the molecular mechanism of PCV2 infection.

Highlights

Porcine circovirus type 2 (PCV2), serving as a member of the family Circoviridae[1], has been demonstrated to associate with postweaning multisystemic wasting syndrome (PMWS) and other clinical diseases, including porcine reproductive failure, dermatitis and nephropathy syndrome, necrotizing tracheitis, fetal myocarditis as well as congenital tremors, which is collectively considered as porcine circovirus type 2 (PCV2)-associated diseases (PCVAD)[2]
At 48 h postinfection, we found that PCV2 infection caused significant increases in the levels of γH 2AX and phosphorylated RPA32 at serine 33 (p-RPA32) in ORF1-expressing cells (Fig. 1B and C, PCV2-infected), with most of the ORF1-expressing cells positive for anti-γH2AX and p-RPA32, respectively
We investigated the interaction of PCV2 with the cellular DNA damage response pathway

Summary

Introduction

Porcine circovirus type 2 (PCV2), serving as a member of the family Circoviridae[1], has been demonstrated to associate with postweaning multisystemic wasting syndrome (PMWS) and other clinical diseases, including porcine reproductive failure, dermatitis and nephropathy syndrome, necrotizing tracheitis, fetal myocarditis as well as congenital tremors, which is collectively considered as PCV2-associated diseases (PCVAD)[2]. Cellular DNA damage induced by intrinsic or extrinsic insults activates a DNA damage response (DDR) that produces a complex protein kinase signaling cascade including cell cycle checkpoint activation, DNA repair, or apoptosis induction[8]. Once at the damage site, these DDR kinases phosphorylate amounts of substrates including RPA32, H2AX, Chk[1], Chk[2], Nbs[1], and p53 that followed by targeting other proteins, whereby leading to cell cycle arrest or induction of apoptosis[9,21,22]. Infection of DNA viruses has been shown to induce a cellular DNA damage response, which can prevent or facilitate viral DNA replication, and promote the damaged DNA repair, cell cycle checkpoint activation or apoptotic responses in infected cells[23,24]. As a DNA virus, there is still no report on a DDR induced by PCV2 infection and the DDR contributes to PCV2 replication and apoptotic responses

Methods

Results

Conclusion