scholarly journals Evidence Supporting a Role for TopBP1 and Brd4 in the Initiation but Not Continuation of Human Papillomavirus 16 E1/E2-Mediated DNA Replication

2015 ◽  
Vol 89 (9) ◽  
pp. 4980-4991 ◽  
Author(s):  
Elaine J. Gauson ◽  
Mary M. Donaldson ◽  
Edward S. Dornan ◽  
Xu Wang ◽  
Molly Bristol ◽  
...  
Keyword(s):  
Human Papillomavirus ◽  
Dna Replication ◽  
Viral Proteins ◽  
Future Generations ◽  
Cellular Proteins ◽  
Origin Of Replication ◽  
Viral Dna ◽  
Viral Origin ◽  
Viral Dna Replication ◽  
Human Papillomavirus 16

ABSTRACTTo replicate the double-stranded human papillomavirus 16 (HPV16) DNA genome, viral proteins E1 and E2 associate with the viral origin of replication, and E2 can also regulate transcription from adjacent promoters. E2 interacts with host proteins in order to regulate both transcription and replication; TopBP1 and Brd4 are cellular proteins that interact with HPV16 E2. Previous work with E2 mutants demonstrated the Brd4 requirement for the transactivation properties of E2, while TopBP1 is required for DNA replication induced by E2 from the viral origin of replication in association with E1. More-recent studies have also implicated Brd4 in the regulation of DNA replication by E2 and E1. Here, we demonstrate that both TopBP1 and Brd4 are present at the viral origin of replication and that interaction with E2 is required for optimal initiation of DNA replication. Both cellular proteins are present in E1-E2-containing nuclear foci, and the viral origin of replication is required for the efficient formation of these foci. Short hairpin RNA (shRNA) against either TopBP1 or Brd4 destroys the E1-E2 nuclear bodies but has no effect on E1-E2-mediated levels of DNA replication. An E2 mutation in the context of the complete HPV16 genome that compromises Brd4 interaction fails to efficiently establish episomes in primary human keratinocytes. Overall, the results suggest that interactions between TopBP1 and E2 and between Brd4 and E2 are required to correctly initiate DNA replication but are not required for continuing DNA replication, which may be mediated by alternative processes such as rolling circle amplification and/or homologous recombination.IMPORTANCEHuman papillomavirus 16 (HPV16) is causative in many human cancers, including cervical and head and neck cancers, and is responsible for the annual deaths of hundreds of thousands of people worldwide. The current vaccine will save lives in future generations, but antivirals targeting HPV16 are required for the alleviation of disease burden on the current, and future, generations. Targeting viral DNA replication that is mediated by two viral proteins, E1 and E2, in association with cellular proteins such as TopBP1 and Brd4 would have therapeutic benefits. This report suggests a role for these cellular proteins in the initiation of viral DNA replication by HPV16 E1-E2 but not for continuing replication. This is important if viral replication is to be effectively targeted; we need to understand the viral and cellular proteins required at each phase of viral DNA replication so that it can be effectively disrupted.

scholarly journals Calcein represses human papillomavirus 16 E1-E2 mediated DNA replication via blocking their binding to the viral origin of replication

Virology ◽  
2017 ◽  
Vol 508 ◽  
pp. 180-187 ◽  
Author(s):  
Dipon Das ◽  
Nathan W. Smith ◽  
Xu Wang ◽  
Stacie L. Richardson ◽  
Matthew C.T. Hartman ◽  
...  
Keyword(s):  
Human Papillomavirus ◽  
Dna Replication ◽  
Origin Of Replication ◽  
Viral Origin ◽  
Human Papillomavirus 16

scholarly journals An Interaction between Human Papillomavirus 16 E2 and TopBP1 Is Required for Optimum Viral DNA Replication and Episomal Genome Establishment

2012 ◽  
Vol 86 (23) ◽  
pp. 12806-12815 ◽  
Author(s):  
M. M. Donaldson ◽  
L. J. Mackintosh ◽  
J. M. Bodily ◽  
E. S. Dornan ◽  
L. A. Laimins ◽  
...  
Keyword(s):  
Human Papillomavirus ◽  
Dna Replication ◽  
Viral Dna ◽  
Viral Dna Replication ◽  
Human Papillomavirus 16

scholarly journals Persistent Human Papillomavirus Infection

Viruses ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 321
Author(s):  
Ashley N. Della Fera ◽  
Alix Warburton ◽  
Tami L. Coursey ◽  
Simran Khurana ◽  
Alison A. McBride
Keyword(s):  
Human Papillomavirus ◽  
Dna Replication ◽  
Cellular Proliferation ◽  
Basal Cells ◽  
Viral Dna ◽  
Viral Dna Replication ◽  
Viral Genomes ◽  
Cellular Environment ◽  
E6 And E7 ◽  
Cellular Replication

Persistent infection with oncogenic human papillomavirus (HPV) types is responsible for ~5% of human cancers. The HPV infectious cycle can sustain long-term infection in stratified epithelia because viral DNA is maintained as low copy number extrachromosomal plasmids in the dividing basal cells of a lesion, while progeny viral genomes are amplified to large numbers in differentiated superficial cells. The viral E1 and E2 proteins initiate viral DNA replication and maintain and partition viral genomes, in concert with the cellular replication machinery. Additionally, the E5, E6, and E7 proteins are required to evade host immune responses and to produce a cellular environment that supports viral DNA replication. An unfortunate consequence of the manipulation of cellular proliferation and differentiation is that cells become at high risk for carcinogenesis.

scholarly journals Activation of Chromosomal DNA Replication inSaccharomyces cerevisiae by Acidic Transcriptional Activation Domains

1998 ◽  
Vol 18 (3) ◽  
pp. 1296-1302 ◽  
Author(s):  
Rong Li ◽  
David S. Yu ◽  
Masafumi Tanaka ◽  
Liyi Zheng ◽  
Shelley L. Berger ◽  
...  
Keyword(s):  
Dna Replication ◽  
Transcriptional Activation ◽  
Origin Of Replication ◽  
Chromosomal Dna ◽  
Viral Dna ◽  
Chromosomal Replication ◽  
Autonomously Replicating Sequence ◽  
Viral Dna Replication ◽  
Activation Domains ◽  
Transcriptional Activation Domains

ABSTRACT A large body of evidence from viral systems has established that transcription factors play an important and direct role in activating viral DNA replication. Among the transcriptional activation domains that can stimulate viral DNA replication are acidic domains such as those derived from herpes simplex virus VP16 and the tumor suppressor p53. Here we show that acidic activation domains can also activate a cellular origin of replication in a chromosomal context. When tethered to the yeast ARS1 (autonomously replicating sequence 1) origin of replication, both VP16 and p53 activation domains can enhance origin function. In addition, the C-terminal acidic region of the yeast transcription factor ABF1, which normally activates the ARS1 origin, is sufficient for activating ARS1 function when tethered to the origin. Mutations at residues Trp-53 and Phe-54 of a 20-residue (41 to 60) activation region of p53 abolish the activation of both replication and transcription, suggesting that the same structural determinants may be employed to activate both processes in yeast. Furthermore, using a two-dimensional gel electrophoresis method, we demonstrate that the GAL4-p53 chimeric activator can activate initiation of chromosomal replication from an origin inserted at the native ARS1 locus. These findings strongly suggest functional conservation of the mechanisms used by the acidic activation domains to activate viral DNA replication in mammalian cells and chromosomal replication in yeast.

scholarly journals The Inhibitory Action of P56 on Select Functions of E1 Mediates Interferon's Effect on Human Papillomavirus DNA Replication

2010 ◽  
Vol 84 (24) ◽  
pp. 13036-13039 ◽  
Author(s):  
Paramananda Saikia ◽  
Volker Fensterl ◽  
Ganes C. Sen
Keyword(s):  
Human Papillomavirus ◽  
Dna Replication ◽  
Dna Binding ◽  
Inhibitory Action ◽  
Dna Helicase ◽  
Single Amino Acid ◽  
Viral Dna ◽  
Viral Dna Replication ◽  
Hpv Dna ◽  
Papillomavirus Dna

ABSTRACT The interferon (IFN)-induced protein P56 inhibits human papillomavirus (HPV) DNA replication by binding to HPV E1, which has several distinct functions in initiating viral DNA replication. Here, we determined that P56 inhibited HPV type 18 (HPV18) E1's DNA helicase activity, E2 binding, and HPV Ori sequence-specific DNA binding but not nonspecific DNA binding. We observed that deletion of a single amino acid, F399, produced an E1 mutant that could not bind P56. This E1 mutant retained its ability to support Ori DNA replication, but this activity was not inhibited by IFN, demonstrating that P56 is the principal executor of the anti-HPV action of IFN.

scholarly journals Herpes Simplex Virus DNA Synthesis Is Not a Decisive Regulatory Event in the Initiation of Lytic Viral Protein Expression in Neurons In Vivo during Primary Infection or Reactivation from Latency

2006 ◽  
Vol 80 (1) ◽  
pp. 38-50 ◽  
Author(s):  
N. M. Sawtell ◽  
R. L. Thompson ◽  
R. L. Haas
Keyword(s):  
Gene Expression ◽  
Dna Replication ◽  
Dna Synthesis ◽  
Sensory Neurons ◽  
Viral Proteins ◽  
Lytic Cycle ◽  
Viral Dna ◽  
Viral Dna Replication ◽  
Simplex Virus

ABSTRACT The herpes simplex virus genome can enter a repressed transcriptional state (latency) in sensory neurons of the host nervous system. Although reduced permissiveness of the neuronal environment is widely accepted as a causal factor, the molecular pathway(s) directing and maintaining the viral genome in the latent state remains undefined. Over the past decade, the field has been strongly influenced by the observations of Kosz-Vnenchak et al., which have been interpreted to indicate that, in sensory neurons in vivo, a critical level of viral DNA synthesis within the neuron is required for sufficient viral immediate-early (IE) and early (E) gene expression (M. Kosz-Vnenchak, J. Jacobson, D. M. Coen, and D. M. Knipe, J. Virol. 67:5383-5393, 1993). The levels of IE and E genes are, in turn, thought to regulate the decision to enter the lytic cycle or latency. We have reexamined this issue using new strategies for in situ detection and quantification of viral gene expression in whole tissues. Our results using thymidine kinase-null and rescued mutants as well as wild-type strains in conjunction with viral DNA synthesis blockers demonstrate that (i) despite inhibition of viral DNA replication, many neurons express lytic viral proteins, including IE proteins, during acute infection in the ganglion; (ii) at early times postinoculation, the number of neurons expressing viral proteins in the ganglion is not reduced by inhibition of viral DNA replication; and (iii) following a reactivation stimulus, the numbers of neurons and apparent levels of lytic viral proteins, including IE proteins, are not reduced by inhibition of viral DNA replication. We conclude that viral DNA replication in the neuron per se does not regulate IE gene expression or entry into the lytic cycle.

scholarly journals Nuclear Export of Human Papillomavirus Type 31 E1 Is Regulated by Cdk2 Phosphorylation and Required for Viral Genome Maintenance

2010 ◽  
Vol 84 (22) ◽  
pp. 11747-11760 ◽  
Author(s):  
Amélie Fradet-Turcotte ◽  
Cary Moody ◽  
Laimonis A. Laimins ◽  
Jacques Archambault
Keyword(s):  
Human Papillomavirus ◽  
Dna Replication ◽  
Nuclear Export ◽  
Viral Genome ◽  
Cellular Proliferation ◽  
Nuclear Export Signal ◽  
Nuclear Accumulation ◽  
Genome Maintenance ◽  
Viral Dna ◽  
Viral Dna Replication

ABSTRACT The initiator protein E1 from human papillomavirus (HPV) is a helicase essential for replication of the viral genome. E1 contains three functional domains: a C-terminal enzymatic domain that has ATPase/helicase activity, a central DNA-binding domain that recognizes specific sequences in the origin of replication, and a N-terminal region necessary for viral DNA replication in vivo but dispensable in vitro. This N-terminal portion of E1 contains a conserved nuclear export signal (NES) whose function in the viral life cycle remains unclear. In this study, we provide evidence that nuclear export of HPV31 E1 is inhibited by cyclin E/A-Cdk2 phosphorylation of two serines residues, S92 and S106, located near and within the E1 NES, respectively. Using E1 mutant proteins that are confined to the nucleus, we determined that nuclear export of E1 is not essential for transient viral DNA replication but is important for the long-term maintenance of the HPV episome in undifferentiated keratinocytes. The findings that E1 nuclear export is not required for viral DNA replication but needed for genome maintenance over multiple cell divisions raised the possibility that continuous nuclear accumulation of E1 is detrimental to cellular growth. In support of this possibility, we observed that nuclear accumulation of E1 dramatically reduces cellular proliferation by delaying cell cycle progression in S phase. On the basis of these results, we propose that nuclear export of E1 is required, at least in part, to limit accumulation of this viral helicase in the nucleus in order to prevent its detrimental effect on cellular proliferation.

scholarly journals Biology of Ovine Adenovirus Infection of Nonpermissive Cells

2002 ◽  
Vol 76 (21) ◽  
pp. 10882-10893 ◽  
Author(s):  
Daniel Kümin ◽  
Christian Hofmann ◽  
Michael Rudolph ◽  
Gerald W. Both ◽  
Peter Löser
Keyword(s):  
Dna Replication ◽  
Early Stage ◽  
Virus Production ◽  
Adenovirus Type ◽  
Cell Types ◽  
Viral Proteins ◽  
Vector System ◽  
Viral Dna ◽  
Viral Dna Replication ◽  
Wide Range

ABSTRACT Nonhuman adenoviruses, including those of the genus Atadenovirus, have the potential to serve as vectors for vaccine and gene therapy applications in humans, since they are resistant to preexisting immunity induced by human adenoviruses in the majority of the population. In this study, we elucidate the outcome of infection by ovine adenovirus type 7 isolate 287 (OAdV) of several nonovine cell types. We show here that OAdV infects a wide range of nonovine cells but is unable to complete its replication cycle in any of them. In nonovine, nonfibroblast cells, viral replication is blocked at an early stage before the onset of, or early in, DNA replication. Some fibroblasts, on the other hand, allow viral DNA replication but block virus production at a later stage during or after the translation of late viral proteins. Late viral proteins are expressed in cells where viral DNA replication takes place, albeit at a reduced level. Significantly, late proteins are not properly processed, and their cellular distribution differs from that observed in infected ovine cells. Thus, our results clearly show that OAdV infection of all nonovine cells tested is abortive even if significant viral DNA replication occurs. These findings have significant positive implications with respect to the safety of the vector system and its future use in humans.

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