scholarly journals Epidermal growth factor (EGF) elicits down-regulation of human papillomavirus type 16 (HPV-16) E6/E7 mRNA at the transcriptional level in an EGF-stimulated human keratinocyte cell line: functional role of EGF-responsive silencer in the HPV-16 long control region.

1991 ◽  
Vol 65 (4) ◽  
pp. 2000-2009 ◽  
Author(s):  
S Yasumoto ◽  
A Taniguchi ◽  
K Sohma
Keyword(s):  
Human Papillomavirus ◽  
Functional Role ◽  
Long Control Region ◽  
Transcriptional Level ◽  
Hpv 16 ◽  
Human Papillomavirus Type 16 ◽  
Human Keratinocyte ◽  
Keratinocyte Cell ◽  
Epidermal Growth

The interaction between steroid hormones, human papillomavirus type 16, E6 oncogene expression, and cervical cancer

2003 ◽  
Vol 13 (6) ◽  
pp. 834-842 ◽  
Author(s):  
M. Moodley ◽  
S. Sewart ◽  
C. S. Herrington ◽  
R. Chetty ◽  
R. Pegoraro ◽  
...  
Keyword(s):  
Cervical Cancer ◽  
Human Papillomavirus ◽  
Steroid Hormones ◽  
Housekeeping Gene ◽  
Hpv 16 ◽  
Tissue Samples ◽  
Hpv Dna ◽  
Human Papillomavirus Type 16 ◽  
Transforming Proteins

Various risk factors have been implicated in the causation of cervical cancer including human papillomavirus (HPV), the early genes (E6 and E7) of which encode the main transforming proteins. Studies have suggested that steroid hormones may enhance the expression of these genes leading to loss of p53 gene-mediated cell apoptosis. A total of 120 cervical tissue samples were obtained from patients with proven cervical cancer. Patients who used depo-medroxyprogesterone acetate steroid contraception were recruited as part of the steroid arm. Only HPV DNA type 16 samples were used for the study. Controls included three cell lines (CaSki, SiHa, & C33A) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was used as an internal housekeeping gene. Of 120 patients, there were 111 patients with HPV type 16 identified. Of this number, RNA was present in 63 samples. There were 30 women (30/63) who used steroid contraception. In relation to patients who used contraception, HPV 16 E6 gene expression was present in 79% (n = 23) and 88% (n = 30) of steroid users compared to nonusers, respectively. In total there were 25 patients (40%) with expression of the HPV 16 E6*I gene and 30 patients with expression of the E6*II gene. There were 57% of steroid users (n = 17) who had expression of the E6*I/E6*II gene, compared to 52% (n = 17) of nonusers (P = 0.800). From a molecular level, this study does not confirm the role of injectable progesterones in cervical carcinogenesis.

scholarly journals Establishment of the Human Papillomavirus Type 16 (HPV-16) Life Cycle in an Immortalized Human Foreskin Keratinocyte Cell Line

Virology ◽  
1999 ◽  
Vol 262 (2) ◽  
pp. 344-354 ◽  
Author(s):  
Elsa R. Flores ◽  
B.Lynn Allen-Hoffmann ◽  
Denis Lee ◽  
Carol A. Sattler ◽  
Paul F. Lambert
Keyword(s):  
Human Papillomavirus ◽  
Life Cycle ◽  
Cell Line ◽  
Hpv 16 ◽  
Human Papillomavirus Type 16 ◽  
Keratinocyte Cell

scholarly journals Comparison of Variant-Specific Hybridization and Single-Strand Conformational Polymorphism Methods for Detection of Mixed Human Papillomavirus Type 16 Variant Infections

1999 ◽  
Vol 37 (11) ◽  
pp. 3627-3633 ◽  
Author(s):  
Rebecca T. Emeny ◽  
John R. Herron ◽  
Long Fu Xi ◽  
Laura A. Koutsky ◽  
Nancy B. Kiviat ◽  
...  
Keyword(s):  
Human Papillomavirus ◽  
Single Strand ◽  
Sscp Analysis ◽  
Clinical Samples ◽  
Long Control Region ◽  
Single Strand Conformational Polymorphism ◽  
Conformational Polymorphism ◽  
Hpv 16 ◽  
Human Papillomavirus Type 16 ◽  
Specific Hybridization

PCR-based variant-specific hybridization (VSH) and single-strand conformational polymorphism (SSCP) analyses were compared for their capacities to detect mixed human papillomavirus type 16 (HPV-16) variant infections within clinical specimens. The SSCP assay used in this comparison targets a 682-bp fragment that spans nucleotides 7445 to 222 within the HPV-16 genome. This fragment includes portions of the HPV-16 long control region and the E6 open reading frame and identifies three categories of SSCP patterns: those identical to the patterns of prototype HPV-16 (P), those identical to the patterns of Caski-derived HPV-16 (C), or those that are different from the P and C HPV-16 patterns and that are therefore classified as belonging to novel (N) HPV-16 variants. VSH targets the entire HPV-16 E6-coding region (nucleotides 56 to 640) and distinguishes previously described variant nucleotides at positions 109, 131, 132, 143, 145, 178, 286, 289, 350, 403, and 532. Clinical samples used in VSH and SSCP analyses were subjected to multiple independent amplification reactions. The resultant amplicons were cloned, and 14 to 78 clones per clinical specimen were evaluated by VSH. VSH detected an HPV-16 variant that represented at least 20% of the amplified HPV-16 variant population. In contrast, SSCP analysis detected HPV-16 variants that represented 36% of the amplified HPV-16 population. Comparison studies were conducted with mixed HPV-16 variant laboratory constructs. Again, VSH had a higher sensitivity than SSCP analysis in detecting mixed HPV-16 variant infections in these constructed amplicon targets. Accurate detection of HPV-16 variants may enhance our understanding of the natural history of HPV-16 infections.

scholarly journals Identification and functional analysis of sequence rearrangements in the long control region of human papillomavirus type 16 Af-1 variants isolated from Ugandan penile carcinomas

2000 ◽  
Vol 81 (12) ◽  
pp. 2969-2982 ◽  
Author(s):  
Maria Lina Tornesello ◽  
Franco M. Buonaguro ◽  
Luigi Buonaguro ◽  
Immacolata Salatiello ◽  
Elke Beth-Giraldo ◽  
...  
Keyword(s):  
Human Papillomavirus ◽  
Control Region ◽  
Expression Vectors ◽  
Long Control Region ◽  
Hpv 16 ◽  
Expression Levels ◽  
Human Papillomavirus Type 16 ◽  
Transforming Activity ◽  
E6 And E7 ◽  
Cat Expression

Human papillomavirus type 16 (HPV-16) is the predominant HPV isolate found in malignancies of male and female lower genital tracts. However, only a small percentage of individuals infected with high-risk HPVs develop a genital neoplasia, suggesting that additional events at both the cellular and the virus level are necessary for the progression to cancer, including genetic mutations/rearrangements of viral sequences involved in the oncogenic process. In this study, the genetic stability of the long control region (LCR) (nt 7289–114), which regulates expression levels of oncoproteins E6 and E7, was analysed in HPV-16 isolates from penile carcinoma (PC) biopsies of patients recruited from Uganda, one of the countries with the highest incidence of genital cancers in both men and women. Nucleotide changes within the LCR region typical of the African-1 (Af-1) lineage were observed in all HPV-16 isolates. Two out of five samples showed further rearrangements of the enhancer region. The functional activity of LCR with Af-1 mutations and/or rearrangements was evaluated by cloning each LCR into CAT expression vectors, followed by transfection in several epithelial and non-epithelial cell lines. CAT expression levels driven by a rearranged LCR were significantly higher than those driven by Af-1 or European prototype LCRs. Furthermore, in the NIH3T3 focus formation assay, the transforming activity of E6 and E7 genes, driven by a mutated or rearranged LCR, was 1·4- to 3·0-fold higher, respectively. These results indicate that rearrangements within the LCR of HPV-16 isolated from African PCs are frequently found (2 out of 5, 40%). It is also shown that increased HPV LCR activity is associated with an increased E6/E7-mediated in vitro transforming activity, suggesting that natural variants can play a major role in the pathogenesis of genital carcinomas.

Viral transcription in human keratinocyte cell lines immortalized by human papillomavirus type-16

Virology ◽  
1991 ◽  
Vol 183 (1) ◽  
pp. 331-342 ◽  
Author(s):  
M. Rohlfs ◽  
S. Winkenbach ◽  
S. Meyer ◽  
T. Rupp ◽  
M. Dürst
Keyword(s):  
Human Papillomavirus ◽  
Cell Lines ◽  
Viral Transcription ◽  
Human Papillomavirus Type 16 ◽  
Human Keratinocyte ◽  
Keratinocyte Cell

scholarly journals The Chromatin Structure of the Long Control Region of Human Papillomavirus Type 16 Represses Viral Oncoprotein Expression

1999 ◽  
Vol 73 (3) ◽  
pp. 1918-1930 ◽  
Author(s):  
Walter Stünkel ◽  
Hans-Ulrich Bernard
Keyword(s):  
Human Papillomavirus ◽  
Control Region ◽  
Replication Origin ◽  
Chromatin Organization ◽  
Long Control Region ◽  
Promoter Elements ◽  
Hpv 16 ◽  
Human Papillomavirus Type 16 ◽  
Hpv 18

ABSTRACT The long control region (LCR) of human papillomavirus type 16 (HPV-16) has a size of 850 bp (about 12% of the viral genome) and regulates transcription and replication of the viral DNA. The 5′ segment of the LCR contains transcription termination signals and a nuclear matrix attachment region, the central segment contains an epithelial cell-specific enhancer, and the 3′ segment contains the replication origin and the E6 promoter. Here we report observations on the chromatin organization of this part of the HPV-16 genome. Treatment of the nuclei of CaSki cells, a cell line with 500 intrachromosomal copies of HPV-16, with methidiumpropyl-EDTA-Fe(II) reveals nucleosomes in specific positions on the LCR and the E6 and E7 genes. One of these nucleosomes, which we termed Ne, overlaps with the center of the viral enhancer, while a second nucleosome, Np16, overlaps with the replication origin and the E6 promoter. The two nucleosomes become positioned on exactly the same segments after in vitro assembly of chromatin on the cloned HPV-16 LCR. Primer extension mapping of DNase I-cleaved chromatin revealed Np16 to be positioned centrally over E6 promoter elements, extending into the replication origin. Ne covers the center of the enhancer but leaves an AP-1 site, one of the strongestcis-responsive elements of the enhancer, unprotected. Np16, or a combination of Np16 and Ne, represses the activity of the E6 promoter during in vitro transcription of HPV-16 chromatin. Repression is relieved by addition of Sp1 and AP-1 transcription factors. Sp1 alters the structure of Np16 in vitro, while no changes can be observed during the binding of AP-1. HPV-18, which has a similar arrangement ofcis-responsive elements despite its evolutionary divergence from HPV-16, shows specific assembly in vitro of a nucleosome, Np18, over the E1 binding site and E6 promoter elements but positioned about 90 bp 5′ of the position of Np16 on the homologous HPV-16 sequences. The chromatin organization of the HPV-16 and HPV-18 genomes suggests important regulatory roles of nucleosomes during the viral life cycle.

scholarly journals Overlapping YY1- and aberrant SP1-binding sites proximal to the early promoter of human papillomavirus type 16

1999 ◽  
Vol 80 (8) ◽  
pp. 2097-2101 ◽  
Author(s):  
Xiao-Ping Dong ◽  
Herbert Pfister
Keyword(s):  
Human Papillomavirus ◽  
Binding Site ◽  
Binding Sites ◽  
Cellular Proteins ◽  
Long Control Region ◽  
Hpv 16 ◽  
Cervical Carcinomas ◽  
Human Papillomavirus Type 16 ◽  
E6 And E7 ◽  
Transcription Factor Yy1

Transcription of oncogenes E6 and E7 of human papillomavirus type 16 (HPV-16) from the P97 promoter is regulated by viral and cellular proteins. The transcription factor YY1 represses transcription through binding to cognate sequences in the long control region (LCR). In HPV-16 DNA from cervical carcinomas, mutations of YY1-binding sites have been identified that increase P97 activity 3–6-fold. A second, SP1-binding site has now been identified in the HPV-16 LCR (nt 7842–7847), which overlaps the YY1-binding site at positions 7840–7848. A point mutation within this YY1 site in viral DNA from a cervical cancer, previously shown to prevent YY1 binding, was shown to increase SP1 binding and P97 activity 4·7-fold. An engineered mutant eliminating SP1 binding showed only 1- to 1·6-fold increased P97 activity. It is concluded that competition between SP1 and YY1 for DNA binding plays a major role in YY1 repression mediated by the binding site at positions 7840–7848.

scholarly journals A Novel YY1-Independent Silencer Represses the Activity of the Human Papillomavirus Type 16 Enhancer

1998 ◽  
Vol 72 (12) ◽  
pp. 10083-10092 ◽  
Author(s):  
Mark J. O’Connor ◽  
Walter Stünkel ◽  
Holger Zimmermann ◽  
Choon-Heng Koh ◽  
Hans-Ulrich Bernard
Keyword(s):  
Human Papillomavirus ◽  
Transcriptional Repression ◽  
Regulatory Element ◽  
Long Control Region ◽  
Hpv 16 ◽  
General Ability ◽  
Human Papillomavirus Type 16 ◽  
Complex Process ◽  
Important Addition ◽  
Binding Sequence

ABSTRACT Regulation of the human papillomavirus type 16 (HPV-16) E6 promoter is a complex process in which transcriptional repression as well as activation plays an important role. Here, we identify a negative regulatory element that in the context of a continuous long control region fragment overcomes the activation of the HPV-16 enhancer. This silencing element, which we have termed a PSM (papillomavirus silencing motif), consists of two copies of the sequence 5′-TAYAATAAT-3′ that overlap the origin of replication. Each copy of this 9-bp sequence binds the same unknown cellular factor, which we refer to as PSM-BP (PSM binding protein). Both copies of the binding sequence are required for transcriptional repression, and we provide evidence that suggests that this particular organization results in the stabilization of a PSM-BP dimer. The silencing motif, while functioning in either orientation, showed a positional requirement between the enhancer and the promoter. Experiments with both a heterologous enhancer and a promoter also demonstrated a general ability of this element to function as a transcriptional silencer in non-HPV systems. Our findings provide an important addition to our understanding of HPV-16 gene regulation and an interesting model for the study of transcriptional repression.

Sign in / Sign up

Export Citation Format

Share Document