BK Polyomavirus Activates the DNA Damage Response To Prolong S Phase

Abstract

BK polyomavirus (PyV) is a major source of kidney failure in transplant recipients. The standard treatment for patients with lytic BKPyV infection is to reduce immunosuppressive therapy, which increases the risk of graft rejection. PyVs are DNA viruses that rely upon host replication proteins for viral genome replication. A hallmark of PyV infection is activation of the DNA damage response (DDR) to prevent severe host and viral DNA damage that impairs viral production by an unknown mechanism. Therefore, we sought to better understand why BKPyV activates the DDR through the ATR and ATM pathways and how this prevents DNA damage and leads to increased viral production. When ATR was inhibited in BKPyV-infected primary kidney cells, severe DNA damage occurred due to premature Cdk1 activation, which resulted in mitosis of cells that were actively replicating host DNA in S phase. Conversely, ATM was required for efficient entry into S phase and to prevent normal mitotic entry after G 2 phase. The synergistic activation of these DDR kinases promoted and maintained BKPyV-mediated S phase to enhance viral production. In contrast to BKPyV infection, DDR inhibition did not disrupt cell cycle control in uninfected cells. This suggests that DDR inhibitors may be used to specifically target BKPyV-infected cells. IMPORTANCE BK polyomavirus (BKPyV) is an emerging pathogen that reactivates in immunosuppressed organ transplant patients. We wanted to understand why BKPyV-induced activation of the DNA damage response (DDR) enhances viral titers and prevents host DNA damage. Here, we show that the virus activates the DNA damage response in order to keep the infected cells in S phase to replicate the viral DNA. The source of DNA damage was due to actively replicating cells with uncondensed chromosomes entering directly into mitosis when the DDR was inhibited in BKPyV-infected cells. This study clarifies the previously enigmatic role of the DDR during BKPyV infection by demonstrating that the virus activates the DDR to maintain the cells in S phase in order to promote viral replication and that disruption of this cell cycle arrest can lead to catastrophic DNA damage for the host.

Polyploid Giant Cancer Cells, a Hallmark of Oncoviruses and a New Therapeutic Challenge

“…sT induction in C57BL/6 mice resulted in the formation of poorly-differentiated neoplasia pleomorphic nuclei varying in size and shape in conjunction with multiple nucleoli ( 111 ). In agreement with this, BKPyV infection of renal proximal tubule epithelial cells resulted in the accumulation of polyploid cells ( 112 ), an effect also seen upon large tumor antigen (TAg) expression ( 113 ). Alternatively, JCPyV infection of both cerebral hemispheres revealed giant multinucleated astrocytes with pyramidal neurons harboring enlarged nuclei ( 114 ).…”

“…BKPyV was also demonstrated to induce multiple rounds of DNA replication within a single cell ( 112 ). This could be explained by a synergistic cooperation between ataxia telangiectasia, mutated (ATM) and ataxia telangiectasia, and Rad3-related (ATR), where ATM promotes efficient S-phase entry and mitosis block after complete DNA replication, and ATR arrests the cell cycle to prevent entry into mitosis in actively replicating cells, resulting in BKPyV-mediated polyploidization ( 113 ).…”

The Role of the JC Virus in Central Nervous System Tumorigenesis

“…The two human Polyomaviruses BKV and MCPyV also induce the DDR through activation of ATM and ATR kinases. However, these viruses utilize DDR not only to promote their viral replication but also to cause carcinogenesis at the expense of host DNA damage [ 117 , 122 , 123 , 124 , 125 ] ( Figure 2 and Table 1).…”

Murine polyomavirus DNA transitions through spatially distinct nuclear replication subdomains during infection

“…Although FISH identified vDNA at DDR-associated focal RPA32 (Figs 1 and 2), the trafficking of vDNA between VRC subdomains was unclear. EdU labels replicating vDNA within PyV replication centers [8,51,52], so we applied pulse-chase labeling with EdU to identify discrete subpopulations of vDNA at different times post-synthesis ( Fig 3A). The EdU signal immediately after the pulse label (nascent vDNA) localized within VRCs and overlapped with LT, suggesting this subdomain represented the initial site of vDNA synthesis ( Fig 3B and S3A Fig).…”