Human Parvovirus B19 DNA Replication Induces a DNA Damage Response That Is Dispensable for Cell Cycle Arrest at Phase G(2)/M

Department of Infectious Diseases, First Affiliated Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an, China.
Journal of Virology (Impact Factor: 4.44). 07/2012; 86(19):10748-58. DOI: 10.1128/JVI.01007-12
Source: PubMed


Human parvovirus B19 (B19V) infection is highly restricted to human erythroid progenitor cells, in which it induces a DNA damage response (DDR). The DDR signaling is mainly mediated by the ATR (ataxia telangiectasia-mutated and Rad3-related) pathway, which promotes replication of the viral genome; however, the exact mechanisms employed by B19V to take advantage of the DDR for virus replication remain unclear. In this study, we focused on the initiators of the DDR and the role of the DDR in cell cycle arrest during B19V infection. We examined the role of individual viral proteins, which were delivered by lentiviruses, in triggering a DDR in ex vivo-expanded primary human erythroid progenitor cells and the role of DNA replication of the B19V double-stranded DNA (dsDNA) genome in a human megakaryoblastoid cell line, UT7/Epo-S1 (S1). All the cells were cultured under hypoxic conditions. The results showed that none of the viral proteins induced phosphorylation of H2AX or replication protein A32 (RPA32), both hallmarks of a DDR. However, replication of the B19V dsDNA genome was capable of inducing the DDR. Moreover, the DDR per se did not arrest the cell cycle at the G(2)/M phase in cells with replicating B19V dsDNA genomes. Instead, the B19V nonstructural 1 (NS1) protein was the key factor in disrupting the cell cycle via a putative transactivation domain operating through a p53-independent pathway. Taken together, the results suggest that the replication of the B19V genome is largely responsible for triggering a DDR, which does not perturb cell cycle progression at G(2)/M significantly, during B19V infection.

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Available from: Sai Lou, Dec 25, 2013
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    • "NS1 consists of an N-terminal DNA-binding/nickase domain, a central domain displaying sequence motifs for helicase/ATPase, and a C-terminal domain whose function remains unknown (Astell et al., 1997; Doerig et al., 1990; Raab et al., 2002). NS1 is a multi-functional protein that plays a pivotal role in viral DNA replication (Cotmore et al., 2007; Han et al., 2013; Li and Rhode, 1990; Zhi et al., 2006), and has also been implicated in transactivation of viral (Gareus et al., 1998; Raab et al., 2002) and cellular genes (Fu et al., 2002; Moffatt et al., 1996; Nakashima et al., 2004), cell cycle arrest (Luo et al., 2013; Morita et al., 2003; Wan et al., 2010), apoptosis (Moffatt et al., 1998), DNA damage response (Lou et al., 2012; Luo et al., 2011), modulation of host innate immunity (Hsu et al., 2011), and packaging of viral DNA into capsid (Bleker et al., 2006; Cotmore and Tattersall, 2005b). It has been shown that null mutants of B19V NS1 protein in which the translational initiation codon was substituted to termination codon completely abolished the viral infectivity (Zhi et al., 2006). "
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