Human Papillomaviruses Recruit Cellular DNA Repair and Homologous Recombination Factors to Viral Replication Centers

Gillespie, Kenric A.; Mehta, Kavi P.M.; Laimins, Laimonis A.; Moody, Cary A.

doi:10.1128/jvi.00247-12

Cited by 185 publications

(243 citation statements)

References 45 publications

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“…It was recently shown that by activating the ATM pathway, HPV recruits cellular DNA repair and recombination factors into its replication centers during the stable and vegetative phases of its life cycle (62). Our observations that ␥H2AX, ATRIP, and TopBP1 are mobilized into HPV replication centers indicate that during the transient-replication phase, HPV replication also activates the ATR pathway (Fig.…”

Section: Fig 9 U2os Cells Were Transfected With 2 G Of the Hpv18/e8supporting

confidence: 50%

Engagement of the ATR-Dependent DNA Damage Response at the Human Papillomavirus 18 Replication Centers during the Initial Amplification

Reinson

Toots

Kadaja

et al. 2013

J Virol

126

194

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We have previously demonstrated that the human papillomavirus (HPV) genome replicates effectively in U2OS cells after transfection using electroporation. The transient extrachromosomal replication, stable maintenance, and late amplification of the viral genome could be studied for high-and low-risk mucosal and cutaneous papillomaviruses. Recent findings indicate that the cellular DNA damage response (DDR) is activated during the HPV life cycle and that the viral replication protein E1 might play a role in this process. We used a U2OS cell-based system to study E1-dependent DDR activation and the involvement of these pathways in viral transient replication. We demonstrated that the E1 protein could cause double-strand DNA breaks in the host genome by directly interacting with DNA. This activity leads to the induction of an ATM-dependent signaling cascade and cell cycle arrest in the S and G 2 phases. However, the transient replication of HPV genomes in U2OS cells induces the ATR-dependent pathway, as shown by the accumulation of ␥H2AX, ATR-interacting protein (ATRIP), and topoisomerase II␤-binding protein 1 (TopBP1) in viral replication centers. Viral oncogenes do not play a role in this activation, which is induced only through DNA replication or by replication proteins E1 and E2. The ATR pathway in viral replication centers is likely activated through DNA replication stress and might play an important role in engaging cellular DNA repair/recombination machinery for effective replication of the viral genome upon active amplification. P apillomaviruses are species-specific double-stranded DNA (dsDNA) viruses that infect the cutaneous and mucosal epithelia of many vertebrate species (1). Human papillomavirus (HPV) infections are widespread, and this virus is considered a common member of the human epithelial microflora (2). In many cases, infections with papillomaviruses are asymptomatic (3). Nearly 100 different HPV types have been identified (4); infections with low-risk viruses (e.g., HPV type 6b [HPV6b] and HPV11) might induce the formation of benign tumors, such as warts and condylomas, while other types (e.g., HPV16 and HPV18), which are referred to as high-risk types, have been shown to cause anogenital and head and neck cancers (reviewed in reference 5). The viral genomes are maintained in infected cells as extrachromosomal nuclear episomes. The proteins encoded by the E1 and E2 open reading frames (ORFs) load the cellular replication machinery at the origin of the HPV replication (reviewed in reference 6). The E1 protein is an origin recognition factor, which is loaded in a sequence-specific manner by the E2 protein at the replication origin, where it forms the E1 double-hexameric replicative helicase upon oligomerization (7-10). Before the initiation of replication, the oligomeric E1 protein unwinds dsDNA into two single strands, assembles into the double-hexameric, ATP-dependent replicative helicase, and loads the cellular replication complex at replication forks for the initiation of DNA replication (r...

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Section: Fig 9 U2os Cells Were Transfected With 2 G Of the Hpv18/e8supporting

confidence: 50%

Engagement of the ATR-Dependent DNA Damage Response at the Human Papillomavirus 18 Replication Centers during the Initial Amplification

Reinson

Toots

Kadaja

et al. 2013

J Virol

126

194

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“…At present, we can only speculate that this increase in ROS and oxidative DNA damage may contribute to viral genome production. Recent studies suggest that the introduction of doublestrand DNA breaks into HPV DNA during productive replication is an important step in HPV genome amplification and genome maturation (49). Studies have also shown that exposure of cells that normally maintain episomal copies of the HPV genome to physiologically high doses of nitric oxide can lead to upregulation of early E6 and E7 oncogene expression, as well as to a significant increase in DNA double-strand breaks (16).…”

Section: Discussionmentioning

confidence: 99%

Human Papillomavirus Type 16 E6* Induces Oxidative Stress and DNA Damage

Williams

Filippova

Filippov

et al. 2014

J Virol

141

128

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High-risk types of human papillomavirus (HPV) are the causative agents of virtually all cases of cervical cancer and a significant proportion of other anogenital cancers, as well as both oral and pharyngeal cancers. The high-risk types encode two viral oncogenes, E6 and E7, which work together to initiate cell transformation. Multiple steps involving the activities and interactions of both viral and cellular proteins are involved in the progression from HPV infection to cell transformation to cancer. The E6 oncoprotein is expressed as several isoforms: a full-length variant referred to as E6 and a few shorter isoforms collectively referred to as E6*. In this study, we found that expression of E6* increased the level of reactive oxygen species (ROS) in both HPVpositive and HPV-negative cells. This increased oxidative stress led to higher levels of DNA damage, as assessed by the comet assay, quantification of 8-oxoguanine, and poly(ADP-ribose) polymerase 1. The observed increase in ROS may be due to a decrease in cellular antioxidant activity, as we found that E6* expression also led to decreased expression of superoxide dismutase isoform 2 and glutathione peroxidase. These studies indicate that E6* may play an important role in virus-induced mutagenesis by increasing oxidative stress and DNA damage. IMPORTANCEOur findings demonstrate for the first time that an HPV gene product, E6*, can increase ROS levels in host cells. This ability may play a significant role both in the viral life cycle and in cancer development, because an increase in oxidative DNA damage may both facilitate HPV genome amplification and increase the probability of HPV16 DNA integration. Integration, in turn, is thought to be an important step in HPV-mediated carcinogenesis.H igh-risk (HR) types of human papillomavirus (HPV) are the causative agents of virtually all cases of cervical cancer as well as a significant percentage of other anogenital and oropharyngeal cancers. In fact, current estimates indicate that HPV infection may be associated with as many as 93% of anal cancers, 63% of oropharyngeal cancers, 40% of penile cancers, 64% of vaginal cancers, and 51% of vulvar cancers (1). HPV infection accounted for approximately 26,700 cases of HPV-related cancers in the United States (2, 3), and it is estimated that 5.2% of all cancers worldwide can be attributed to HPV infection (4). While the incidence of cervical cancer has declined in the last 30 years due to Pap smear screening, the incidence rates of anal, oropharyngeal, and vulvar cancers steadily increased within the same period (1). These numbers underscore the need for ongoing research into the mechanisms behind HPV-related carcinogenesis.The high-risk types of HPV encode two viral oncogenes, E6 and E7, that together serve as the major initiators of cell transformation (5). Multiple steps are involved in the progression from HPV infection to cellular transformation to cancer. Virus-related factors influencing this progression include virus persistence, viral load, and the repr...

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“…In the viral life cycle, HPV replication is initiated by E2 binding and recruitment of the E1 helicase to the OR (McBride 2008). It also depends on activation of the DNA damage response by ATM (Gillespie et al 2012) and ATR (Reinson et al 2013). Therefore, looped structures and associated rearrangements could be byproducts of aberrant HPV integrant replication.…”

Section: Discussionmentioning

confidence: 99%

Genome-wide analysis of HPV integration in human cancers reveals recurrent, focal genomic instability

et al. 2013

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Genomic instability is a hallmark of human cancers, including the 5% caused by human papillomavirus (HPV). Here we report a striking association between HPV integration and adjacent host genomic structural variation in human cancer cell lines and primary tumors. Whole-genome sequencing revealed HPV integrants flanking and bridging extensive host genomic amplifications and rearrangements, including deletions, inversions, and chromosomal translocations. We present a model of ''looping'' by which HPV integrant-mediated DNA replication and recombination may result in viral-host DNA concatemers, frequently disrupting genes involved in oncogenesis and amplifying HPV oncogenes E6 and E7. Our high-resolution results shed new light on a catastrophic process, distinct from chromothripsis and other mutational processes, by which HPV directly promotes genomic instability.

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Human Papillomaviruses Recruit Cellular DNA Repair and Homologous Recombination Factors to Viral Replication Centers

Cited by 185 publications

References 45 publications

Engagement of the ATR-Dependent DNA Damage Response at the Human Papillomavirus 18 Replication Centers during the Initial Amplification

Engagement of the ATR-Dependent DNA Damage Response at the Human Papillomavirus 18 Replication Centers during the Initial Amplification

Human Papillomavirus Type 16 E6* Induces Oxidative Stress and DNA Damage

Genome-wide analysis of HPV integration in human cancers reveals recurrent, focal genomic instability

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