The Major Tegument Protein of Bovine Herpesvirus 1, VP8, Interacts with DNA Damage Response Proteins and Induces Apoptosis

Abstract

VP8, the gene product in bovine herpesvirus-1 (BoHV-1), is a major tegument protein that is essential for virus replication The major DNA damage response protein, ataxia telangiectasia mutated (ATM), phosphorylates Nijmegen breakage syndrome (NBS1) and structural maintenance of chromosome-1 (SMC1) proteins during the DNA damage response. VP8 was found to interact with ATM and NBS1 during transfection and BoHV-1 infection. However, VP8 did not interfere with phosphorylation of ATM in transfected or BoHV-1-infected cells. In contrast, VP8 inhibited phosphorylation of both NBS1 and SMC1 in transfected cells, as well as in BoHV-1-infected cells, but not in cells infected with a VP8 deletion mutant (BoHV-1ΔU47). Inhibition of NBS1 and SMC1 phosphorylation was observed at 4 h postinfection by nuclear VP8. Furthermore, UV light-induced cyclobutane pyrimidine dimer (CPD) repair was reduced in the presence of VP8, and VP8 in fact enhanced etoposide or UV-induced apoptosis. This suggests that VP8 blocks the ATM/NBS1/SMC1 pathway and inhibits DNA repair. VP8 induced apoptosis in VP8-transfected cells through caspase-3 activation. The fact that BoHV-1 is known to induce apoptosis through caspase-3 activation is in agreement with this observation. The role of VP8 was confirmed by the observation that BoHV-1 induced significantly more apoptosis than BoHV-1ΔU47. These data reveal a potential role of VP8 in the modulation of the DNA damage response pathway and induction of apoptosis during BoHV-1 infection. To our knowledge, the effect of BoHV-1 infection on the DNA damage response has not been characterized. Since BoHV-1ΔU47 was previously shown to be avirulent , VP8 is critical for the progression of viral infection. We demonstrated that VP8 interacts with DNA damage response proteins and disrupts the ATM-NBS1-SMC1 pathway by inhibiting phosphorylation of DNA repair proteins NBS1 and SMC1. Furthermore, interference of VP8 with DNA repair was correlated with decreased cell viability and increased DNA damage-induced apoptosis. These data show that BoHV-1 VP8 developed a novel strategy to interrupt the ATM signaling pathway and to promote apoptosis. These results further enhance our understanding of the functions of VP8 during BoHV-1 infection and provide an additional explanation for the reduced virulence of BoHV-1ΔU47.

Induction of Oxidative DNA Damage in Bovine Herpesvirus 1 Infected Bovine Kidney Cells (MDBK Cells) and Human Tumor Cells (A549 Cells and U2OS Cells)

“…In this study, for the first time, we revealed that BoHV-1 infection of bovine kidney cells induced DNA damage ( Figure 1 ), and that the inhibition of ROS production by either NAC or DPI could rescue the virus infection-induced DNA damage and cell death ( Figure 2 ). Importantly, during our preparation of this manuscript, a paper has been published revealing that BoHV-1 tegument protein VP8 induces cell apoptosis through blocking the DDR proteins including ataxia telangiectasia mutated (ATM), phosphorylates Nijmegen breakage syndrome (NBS1) and structural maintenance of chromosome-1 (SMC1), which may consequently lead to the inhibition of DNA repair [ 45 ]. Thus, it is reasonable to speculate that the induction of DNA damage correlates with BoHV-1-caused cell damage.…”

Cellular Cullin RING Ubiquitin Ligases: Druggable Host Dependency Factors of Cytomegaloviruses

“…By this simple yet elegant mechanism, viruses exploit the cell intrinsic ubiquitin-proteasome system to defeat antiviral immunity. Well-known examples of viral exploitation of DDB1 and/or CRLs include the hepatitis B virus (HBV) protein HBx [84,89,90,91,92], the HIV-1- and HIV-2-encoded protein Vpr [93,94,95,96,97,98,99,100,101,102], HIV-2 Vpx [103,104,105,106,107,108,109], parainfluenza virus (PIV) V proteins [78,110,111,112], bovine herpesvirus 1 (BoHV-1) VP8 [113,114], murine gamma herpesvirus (MHV68) M2 [115], as well as the cytomegalovirus proteins pM27 [116,117,118], pUL35 [119], and pUL145 [120].…”

VP8, the Major Tegument Protein of Bovine Herpesvirus-1, Is Partially Packaged during Early Tegument Formation in a VP22-Dependent Manner

“…VP8, the major tegument protein of BoHV-1, is a product of the U L 47 gene [ 14 ], and plays a versatile role in viral replication [ 4 ], induction of humoral and cell-mediated immunity [ 15 ], alteration of host defense mechanisms [ 16 ], and cell death or apoptosis [ 17 ]. It is a late protein, and is conserved throughout the alphaherpesvirus family [ 14 ].…”