scholarly journals Human Papillomavirus Type 16 E2 Protein Has No Effect on Transcription from Episomal Viral DNA

2003 ◽  
Vol 77 (3) ◽  
pp. 2021-2028 ◽  
Author(s):  
Viviane Bechtold ◽  
Peter Beard ◽  
Kenneth Raj
Keyword(s):  
Human Papillomavirus ◽  
Life Cycle ◽  
Cell Lines ◽  
Trichostatin A ◽  
Viral Dna ◽  
Secondary Importance ◽  
E2 Protein ◽  
Hpv Dna ◽  
Episomal Hpv16 ◽  
E6 And E7

ABSTRACT The human papillomavirus (HPV) E2 protein plays an important role in viral DNA replication. Many studies with high-risk HPVs have demonstrated that the E2 protein can also repress transcription of the E6 and E7 oncogenes. This conclusion, based on experiments carried out with cervical cancer cells bearing integrated HPV genomes, is currently assumed to be applicable to the normal HPV life cycle, in which the viral genomes are episomal. Here, we have tested experimentally whether this assumption is correct. We made use of a pair of isogenic cell lines, W12 and S12. W12 cells contain episomal HPV16 genomes, whereas S12 cells, which are derived from the W12 line, contain HPV DNA as integrated copies. When we expressed E2 in S12 cells, we observed strong repression of E6 and E7 transcription. In contrast, no effect of E2 on the transcription of these genes was detected in W12 cells. While integration of the viral genome into the host DNA contributes to the difference between W12 and S12 cells, integration by itself is not sufficient to explain this difference. Instead, the chromatin structure in the region of the E6 and E7 promoter (p97), which we show to be very different in these two cell lines, is likely to be the cause of the different responsiveness of p97 to the E2 protein. Experiments with the histone deacetylase inhibitor trichostatin A (TSA) indicated that the episomal HPV16 DNA is in a relatively inaccessible state prior to TSA treatment. Our results, together with those of others, suggest that any effect of the E2 protein on the expression of the E6 and E7 genes during the normal viral life cycle is of secondary importance compared to the function of E2 in replication.

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.

High-Risk Human Papillomavirus Affects Prognosis in Patients With Surgically Treated Oropharyngeal Squamous Cell Carcinoma

2006 ◽  
Vol 24 (36) ◽  
pp. 5630-5636 ◽  
Author(s):  
Lisa Licitra ◽  
Federica Perrone ◽  
Paolo Bossi ◽  
Simona Suardi ◽  
Luigi Mariani ◽  
...  
Keyword(s):  
Human Papillomavirus ◽  
High Risk ◽  
Oropharyngeal Cancer ◽  
Clinical Results ◽  
Hpv Dna ◽  
Additional Information ◽  
Second Tumors ◽  
E6 And E7 ◽  
Second Tumor ◽  
P16 Expression

Purpose Human papillomavirus (HPV) DNA tumors actively integrating the E6 and E7 oncogenes have a distinct biologic behavior resulting in a more favorable prognosis. To which extent the viral integration by itself, and/or the associated wild-type (wt) TP53 status, and/or a functional p16 contribute to prognosis is unclear. Patients and Methods To clarify how the presence of high-risk (HR) -HPV, TP53, and p16INK4a status interact with clinical outcome, we considered a retrospective series of 90 consecutive oropharyngeal cancer patients treated primarily with surgery. Results Seventeen (19%) patients showed integrated HPV 16 DNA (HPV positive), wt TP53 in all but two patients, normal p16INK4a in 15 assessable patients, and p16 expression in all 17 patients. Thirty-five patients (39%), two of whom were HPV positive, harbored TP53 mutations. p16INK4a deletion and p16 null immunophenotype occurred in 28 and 58 patients, respectively, and was similarly distributed in both patients with mutated TP53 (48% and 82%, respectively) and in patients with wt TP53 (46% and 77%, respectively). Statistical analysis showed that HPV-positive status significantly affects all investigated end points: overall survival (P = .0018), incidence of tumor relapse (P = .0371), and second tumor (P = .0152), whereas TP53 and p16INK4a status and p16 expression were not prognostic by themselves. Conclusion Our molecular and clinical results are in agreement with previous findings but provide additional information into the biologic mechanisms involved in HR-HPV oropharyngeal cancer in comparison to HPV-negative tumors. According to the reduced risk of relapse and second tumors associated with HR-HPV positivity of oropharyngeal cancer, the therapeutic strategy and follow-up procedures should be reviewed.

scholarly journals Human Papillomavirus E2 Protein: Linking Replication, Transcription, and RNA Processing

2016 ◽  
Vol 90 (19) ◽  
pp. 8384-8388 ◽  
Author(s):  
Sheila V. Graham
Keyword(s):  
Human Papillomavirus ◽  
Life Cycle ◽  
Rna Processing ◽  
Nucleic Acid Binding ◽  
Viral Production ◽  
Interaction Domain ◽  
E2 Protein ◽  
Protein Protein Interaction ◽  
Cellular Environment

The human papillomavirus (HPV) life cycle is tightly linked to differentiation of the infected epithelium. This means that viral proteins must exert control over epithelial gene expression in order to optimize viral production. The HPV E2 protein controls replication, transcription, and viral genome partitioning during the viral infectious life cycle. It consists of a nucleic acid-binding domain and a protein-protein interaction domain separated by a flexible serine and arginine-rich hinge region. Over the last few years, mounting evidence has uncovered an important new role for E2 in viral and cellular RNA processing. This Gem discusses the role of E2 in controlling the epithelial cellular environment and how E2 might act to coordinate late events in the viral replication cycle.

Inverse relationship between the expression of the human papillomavirus type 16 transcription factor E2 and virus DNA copy number during the progression of cervical intraepithelial neoplasia

Microbiology ◽  
2000 ◽  
Vol 81 (7) ◽  
pp. 1825-1832 ◽  
Author(s):  
Mark Stevenson ◽  
Lucy C. Hudson ◽  
Julie E. Burns ◽  
Roy L. Stewart ◽  
Michael Wells ◽  
...  
Keyword(s):  
Human Papillomavirus ◽  
Cervical Intraepithelial Neoplasia ◽  
Intraepithelial Neoplasia ◽  
Lower Grade ◽  
Invasive Squamous Cell Carcinoma ◽  
Hpv 16 ◽  
E2 Protein ◽  
Hpv Dna ◽  
Human Papillomavirus Type 16 ◽  
Invasive Carcinomas

The human papillomavirus type 16 (HPV-16) status of 43 cervical biopsies, which had been characterized histologically as normal, various grades of cervical intraepithelial neoplasia (CIN) and invasive squamous cell carcinoma, was examined by using (i) a novel antibody against the HPV-16 E2 protein, (ii) sensitive HPV-16 DNA in situ hybridization and (iii) microdissection/PCR for the E2 ORF. The data indicate that E2 protein expression is highest in koilocytes in lower-grade CIN (I), but decreases with increasing grade, whereas the detection of HPV DNA is delayed until CIN I/II, rising to the highest levels in carcinoma cells. Co-localization of E2 with HPV-16 DNA-positive cells was most commonly observed in koilocytes in CIN II lesions. PCR analyses of microdissected epithelium from the same or serial sections indicated that E2 ORFs were retained in an intact form in a number of higher-grade CIN lesions and invasive carcinomas.

scholarly journals Chaperone Proteins Abrogate Inhibition of the Human Papillomavirus (HPV) E1 Replicative Helicase by the HPV E2 Protein

2002 ◽  
Vol 22 (18) ◽  
pp. 6592-6604 ◽  
Author(s):  
Biing Yuan Lin ◽  
Alexander M. Makhov ◽  
Jack D. Griffith ◽  
Thomas R. Broker ◽  
Louise T. Chow
Keyword(s):  
Human Papillomavirus ◽  
Topoisomerase I ◽  
Atp Binding ◽  
Dna Unwinding ◽  
Chaperone Proteins ◽  
Viral Origin ◽  
Replicative Helicase ◽  
E2 Protein ◽  
Hpv Dna ◽  
Atp Binding Site

ABSTRACT Human papillomavirus (HPV) DNA replication requires the viral origin recognition protein E2 and the presumptive viral replicative helicase E1. We now report for the first time efficient DNA unwinding by a purified HPV E1 protein. Unwinding depends on a supercoiled DNA substrate, topoisomerase I, single-stranded-DNA-binding protein, and ATP, but not an origin. Electron microscopy revealed completely unwound molecules. Intermediates contained two single-stranded loops emanating from a single protein complex, suggesting a bidirectional E1 helicase which translocated the flanking DNA in an inward direction. We showed that E2 protein partially inhibited DNA unwinding and that Hsp70 or Hsp40, which we reported previously to stimulate HPV-11 E1 binding to the origin and promote dihexameric E1 formation, apparently displaced E2 and abolished inhibition. Neither E2 nor chaperone proteins were detected in unwinding complexes. These results suggest that chaperones play important roles in the assembly and activation of a replicative helicase in higher eukaryotes. An E1 mutation in the ATP binding site caused deficient binding and unwinding of origin DNA, indicating the importance of ATP binding in efficient helicase assembly on the origin.

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 Identification of High-Risk Human Papillomavirus DNA, p16 and E6/E7 Oncoproteins in Laryngeal and Hypopharyngeal Squamous Cell Carcinomas

Viruses ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1008
Author(s):  
Andrejs Lifsics ◽  
Valerija Groma ◽  
Maksims Cistjakovs ◽  
Sandra Skuja ◽  
Renars Deksnis ◽  
...  
Keyword(s):  
Human Papillomavirus ◽  
High Risk ◽  
Squamous Cell ◽  
Surrogate Marker ◽  
Hpv Infection ◽  
Hpv16 E6 ◽  
Hpv Dna ◽  
Molecular Virology ◽  
Hpv E6 ◽  
E6 And E7

Human papillomavirus (HPV) was proven to play a significant role in cancer development in the oropharynx. However, its role in the development of laryngeal (LSCC) and hypopharyngeal squamous cell carcinoma (HPSCC) remains to be clarified. High-risk HPV (HR-HPV) viral proteins E6 and E7 are considered to be pertinent to HPV-related carcinogenesis. Hence, our aim was to estimate LSCC and HPSCC for HR-HPV DNA, p16, and E6/E7 oncoprotein status by using molecular virology and immunohistochemistry methods. The prevalence of HPV16 infection was 22/41 (53.7%) and 20/31 (64.5%) for LSCC and HPSCC, accordingly. The majority of HPV16+ tumor samples were stage III or IV. In most samples, the presence of either HPV16 E6 or HPV16 E7 viral protein in dysplastic or tumor cells was confirmed using immunohistochemistry. Our results suggest a high prevalence of HPV16 as a primary HR-HPV type in LSCC and HPSCC. The lack of HPV E6/E7 oncoproteins in some tumor samples may suggest either the absence of viral integration or the presence of other mechanisms of tumorigenesis. The utilization of p16 IHC as a surrogate marker of HR-HPV infection is impractical in LSCC and HPSCC.

scholarly journals The HPV16 E2 transcriptional regulator mode of action depends on the physical state of the viral genome.

2005 ◽  
Vol 52 (4) ◽  
pp. 823-832 ◽  
Author(s):  
Marcin T Schmidt ◽  
Agnieszka K Olejnik ◽  
Anna Goździcka-Józefiak
Keyword(s):  
Control Region ◽  
Viral Genome ◽  
Hormone Receptors ◽  
Long Control Region ◽  
Viral Dna ◽  
E2 Protein ◽  
E6 And E7 Oncoproteins ◽  
E6 And E7 ◽  
Episomal Dna

Human papillomavirus (HPV) infection is a major risk factor for the development of cervical cancer. The HPV-induced immortalization of epithelial cell usually requires integration of the viral DNA into the host cell genome. The integration event causes disruption of the E2 gene and this is followed by overexpression of the E6 and E7 oncoproteins. The E2 protein is a transcription factor that regulates expression of the E6 and E7 oncoproteins by binding to four sites within the viral long control region. We used an in vitro cell culture model to explore the role of the E2 protein in the transcriptional control of the HPV16 long control region. Employing transient and stable transfection experiments we simulated the episomal and integrated states of the viral genome, respectively. We show that the E2 protein up-regulates E6/E7 transcription from episomal DNA but represses it in the case of integrated DNA. The activator function of the E2 protein seems to counteract the repressive chromatin structure formed over episomal DNA. Steroid hormones and retinol also modulate oncogene transcription differently depending on the physical structure of the viral DNA. Our data suggest regulatory mechanisms involving interactions between the E2 protein and nuclear hormone receptors.

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