scholarly journals Cellular Distribution of Tumour Suppressor Protein p53 and High-Risk Human Papillomavirus (HPV)-18 E6 Fusion Protein in Wild-Type p53 Cell Lines

2008 ◽  
Vol 36 (5) ◽  
pp. 1015-1021 ◽  
Author(s):  
L Sun ◽  
G Gzhang ◽  
Z Li ◽  
T Lei ◽  
C Huang ◽  
...  
Keyword(s):  
High Risk ◽  
Fluorescent Protein ◽  
P53 Protein ◽  
Expression System ◽  
Human Papillomaviruses ◽  
Tumour Suppressor ◽  
Wild Type ◽  
Hpv E6 ◽  
Wild Type P53 ◽  
High Risk Hpv

Human papillomaviruses (HPVs) are very important pathogens that can be classified as high- and low-risk types based on the lesions they cause. Mucosal high-risk HPV E6 can target and degrade the tumour suppressor p53, hence it is recognized as the major cause of cervical cancer, however, due to a lack of reliable anti-E6 antibodies, the distribution of high-risk HPV E6 protein remains elusive. The present study, therefore, used a mammalian green fluorescent protein (GFP) expression system to express GFP-18 E6 fusion proteins in wild-type p53 cells, SMMC-7721 and HCT116, in order to trace the location and expression of HPV E6 and p53 protein. Following transfection, expression of GFP-18 E6 was found to be located in the nucleus, and endogenous wild-type p53 was also located there with GFP-18 E6.

scholarly journals Human Papillomavirus Oncoprotein E6 Inactivates the Transcriptional Coactivator Human ADA3

2002 ◽  
Vol 22 (16) ◽  
pp. 5801-5812 ◽  
Author(s):  
Ajay Kumar ◽  
Yongtong Zhao ◽  
Gaoyuan Meng ◽  
Musheng Zeng ◽  
Seetha Srinivasan ◽  
...  
Keyword(s):  
High Risk ◽  
P53 Protein ◽  
Human Papillomaviruses ◽  
Transcriptional Coactivator ◽  
Interacting Protein ◽  
Hpv E6 ◽  
Cycle Arrest ◽  
Evolutionarily Conserved ◽  
Novel Strategy ◽  
High Risk Hpv

ABSTRACT High-risk human papillomaviruses (HPVs) are associated with carcinomas of the cervix and other genital tumors. The HPV oncoprotein E6 is essential for oncogenic transformation. We identify here hADA3, human homologue of the yeast transcriptional coactivator yADA3, as a novel E6-interacting protein and a target of E6-induced degradation. hADA3 binds selectively to the high-risk HPV E6 proteins and only to immortalization-competent E6 mutants. hADA3 functions as a coactivator for p53-mediated transactivation by stabilizing p53 protein. Notably, three immortalizing E6 mutants that do not induce direct p53 degradation but do interact with hADA3 induced the abrogation of p53-mediated transactivation and G1 cell cycle arrest after DNA damage, comparable to wild-type E6. These findings reveal a novel strategy of HPV E6-induced loss of p53 function that is independent of direct p53 degradation. Given the likely role of the evolutionarily conserved hADA3 in multiple coactivator complexes, inactivation of its function may allow E6 to perturb numerous cellular pathways during HPV oncogenesis.

scholarly journals The E6 Oncoproteins of High-Risk Papillomaviruses Bind to a Novel Putative GAP Protein, E6TP1, and Target It for Degradation

1999 ◽  
Vol 19 (1) ◽  
pp. 733-744 ◽  
Author(s):  
Qingshen Gao ◽  
Seetha Srinivasan ◽  
Sarah N. Boyer ◽  
David E. Wazer ◽  
Vimla Band
Keyword(s):  
High Risk ◽  
P53 Protein ◽  
Single Gene ◽  
Human Papillomaviruses ◽  
Dominant Negative ◽  
Hpv16 E6 ◽  
Hpv E6 ◽  
E6 Oncoprotein ◽  
E6 Protein

ABSTRACT The high-risk human papillomaviruses (HPVs) are associated with carcinomas of the cervix and other genital tumors. Previous studies have identified two viral oncoproteins, E6 and E7, which are expressed in the majority of HPV-associated carcinomas. The ability of high-risk HPV E6 protein to immortalize human mammary epithelial cells (MECs) has provided a single-gene model to study the mechanisms of E6-induced oncogenic transformation. In this system, the E6 protein targets the p53 tumor suppressor protein for degradation, and mutational analyses have shown that E6-induced degradation of p53 protein is required for MEC immortalization. However, the inability of most dominant-negative p53 mutants to induce efficient immortalization of MECs suggests the existence of additional targets of the HPV E6 oncoprotein. Using the yeast two-hybrid system, we have isolated a novel E6-binding protein. This polypeptide, designated E6TP1 (E6-targeted protein 1), exhibits high homology to GTPase-activating proteins for Rap, including SPA-1, tuberin, and Rap1GAP. The mRNA for E6TP1 is widely expressed in tissues and in vitro-cultured cell lines. The gene for E6TP1 localizes to chromosome 14q23.2-14q24.3 within a locus that has been shown to undergo loss of heterozygosity in malignant meningiomas. Importantly, E6TP1 is targeted for degradation by the high-risk but not the low-risk HPV E6 proteins both in vitro and in vivo. Furthermore, the immortalization-competent but not the immortalization-incompetent HPV16 E6 mutants target the E6TP1 protein for degradation. Our results identify a novel target for the E6 oncoprotein and provide a potential link between HPV E6 oncogenesis and alteration of a small G protein signaling pathway.

scholarly journals Two Polymorphic Variants of Wild-Type p53 Differ Biochemically and Biologically

1999 ◽  
Vol 19 (2) ◽  
pp. 1092-1100 ◽  
Author(s):  
Miranda Thomas ◽  
Ann Kalita ◽  
Sylvie Labrecque ◽  
David Pim ◽  
Lawrence Banks ◽  
...  
Keyword(s):  
P53 Protein ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Wild Type ◽  
Hpv E6 ◽  
Induced Tumors ◽  
Wild Type P53 ◽  
The Difference ◽  
E6 Protein ◽  
Increased Susceptibility

ABSTRACT The wild-type p53 protein exhibits a common polymorphism at amino acid 72, resulting in either a proline residue (p53Pro) or an arginine residue (p53Arg) at this position. Despite the difference that this change makes in the primary structure of the protein resulting in a difference in migration during sodium dodecyl sulfate-polyacrylamide gel electrophoresis, no differences in the biochemical or biological characteristics of these wild-type p53 variants have been reported. We have recently shown that p53Arg is significantly more susceptible than p53Pro to the degradation induced by human papillomavirus (HPV) E6 protein. Moreover, this may result in an increased susceptibility to HPV-induced tumors in homozygous p53Argindividuals. In further investigating the characteristics of these p53 variants, we now show that both forms are morphologically wild type and do not differ in their ability to bind to DNA in a sequence-specific manner. However, there are a number of differences between the p53 variants in their abilities to bind components of the transcriptional machinery, to activate transcription, to induce apoptosis, and to repress the transformation of primary cells. These observations may have implications for the development of cancers which harbor wild-type p53 sequences and possibly for the ability of such tumors to respond to therapy, depending on their p53 genotype.

Molecular analysis of different allelic variants of wild-type human p53

1992 ◽  
Vol 70 (10-11) ◽  
pp. 1014-1019 ◽  
Author(s):  
France Moreau ◽  
Greg Matlashewski
Keyword(s):  
Cultured Cells ◽  
Human Cancer ◽  
P53 Protein ◽  
Suppressor Gene ◽  
Tumour Suppressor Gene ◽  
Tumour Suppressor ◽  
Allelic Variant ◽  
Wild Type ◽  
Allelic Variants ◽  
Wild Type P53

The p53 tumour suppressor gene is intensively studied because mutations in this gene are the most common genetic alteration so far identified in human cancer. Considerable emphasis has thus been placed on characterizing the biological differences between mutant and wild-type p53 protein. This has led to the realization that in cultured cells, mutant p53 behaves like an oncogene, whereas wild-type p53 is a tumour suppressor gene. The p53 protein is also a target for the tumour virus oncogene products SV40 large T, adenovirus E1B, and human papillomavirus type 16 E6, which are all capable of forming complexes to the p53 protein. Although p53 represents an extremely important cellular regulatory molecule which is well conserved, there exists two allelic variants of wild-type human p53 that differ both in primary and confirmational structure. One variant contains an arginine at amino acid 72 (p53Arg), whereas the other form contains a proline at this residue (p53Pro). The possible implications for more than one allelic variant of wild-type human p53 in the general population is unknown. The present study was undertaken to compare some of the biological features of the different wild-type p53 variants. We present data demonstrating that there was a post-transcriptional selection against accumulation of both variants of wild-type human p53 in 3T3-A31 cells, arguing that both forms are proliferation inhibitory in these cells. Both variants of human p53 were stabilized by SV40 large T, but did not displace mouse p53 from SV40 large T. Neither allelic variant of human p53 was able to reduce significantly SV40-mediated anchorage-independent growth of 3T3-A31 cells. Taken together, these data suggest that although there are structurally different variants of wild-type human p53, there is no difference in the biological activity of these molecules at the level of the biological assays performed here.Key words: human p53, large T, transformation, oncogenes, tumour suppressor.

scholarly journals Recognition of high-risk HPV E6 oncoproteins by 14-3-3 proteins studied by interactomics and crystallography

2020 ◽  
Author(s):  
Gergo Gogl ◽  
Kristina V. Tugaeva ◽  
Pascal Eberling ◽  
Camille Kostmann ◽  
Gilles Trave ◽  
...  
Keyword(s):  
High Risk ◽  
Fluorescence Polarization ◽  
Pdz Domain ◽  
Human Papillomaviruses ◽  
Binding Motif ◽  
Hpv E6 ◽  
Sequence Variations ◽  
Hpv18 E6 ◽  
Isoform Specificity ◽  
High Risk Hpv

AbstractIn tumors induced by high-risk mucosal human papillomaviruses (hrm-HPVs), HPV E6 oncoproteins inhibit apoptotic processes and sustain cell proliferation. E6 from all hrm-HPVs harbor a C-terminal short PDZ domain-binding motif (PBM), whose phosphorylation down-regulates PDZ binding but triggers E6 binding to 14-3-3 proteins. Here we classify PBMs of E6 proteins depending on their principle ability to be phosphorylated and subsequently acquire a 14-3-3-binding motif III consensus, (pS/pT)XX-COOH. Systematic competitive fluorescence polarization measurements show that the PBMs from four selected E6 oncoproteins bind all seven human 14-3-3 isoforms with distinct, wide-ranging affinities, obeying remarkable trends assigned to 14-3-3 isoform specificity and small E6 sequence variations. We crystallized the hrm-HPV18 E6 PBM bound to 14-3-3ζ, revealing a 14-3-3-motif III complex at 1.9 Å resolution. Using fluorescence polarization and crystallography, we also demonstrate that fusicoccin, a molecule that reinforces many known 14-3-3 complexes, destabilizes the 14-3-3-E6 interaction, indicating the druggability of that complex.

scholarly journals Human Scribble (Vartul) Is Targeted for Ubiquitin-Mediated Degradation by the High-Risk Papillomavirus E6 Proteins and the E6AP Ubiquitin-Protein Ligase

2000 ◽  
Vol 20 (21) ◽  
pp. 8244-8253 ◽  
Author(s):  
Shunsuke Nakagawa ◽  
Jon M. Huibregtse
Keyword(s):  
High Risk ◽  
Tumor Suppressor ◽  
Tight Junctions ◽  
Fluorescent Protein ◽  
Pdz Domain ◽  
Cell Junction ◽  
Human Homolog ◽  
Ubiquitin Protein Ligase ◽  
Hpv E6 ◽  
High Risk Hpv

ABSTRACT The high-risk human papillomavirus (HPV) E6 proteins stimulate the ubiquitination and degradation of p53, dependent on the E6AP ubiquitin-protein ligase. Other proteins have also been shown to be targeted for degradation by E6, including hDlg, the human homolog of the Drosophila melanogaster Discs large (Dlg) tumor suppressor. We show here that the human homolog of theDrosophila Scribble (Vartul) (hScrib) tumor suppressor protein is also targeted for ubiquitination by the E6-E6AP complex in vitro and that expression of E6 induces degradation of hScrib in vivo. Characterization of the E6AP-E6-hScrib complex indicated that hScrib binds directly to E6 and that the binding is mediated by the PDZ domains of hScrib and a carboxyl-terminal epitope conserved among the high-risk HPV E6 proteins. Green fluorescent protein-hScrib was localized to the periphery of MDCK cells, where it colocalized with ZO-1, a component of tight junctions. E6 expression resulted in loss of integrity of tight junctions, as measured by ZO-1 localization, and this effect was dependent on the PDZ binding epitope of E6. Thus, the high-risk HPV E6 proteins induce the degradation of the human homologs of two Drosophila PDZ domain-containing tumor suppressor proteins, hDlg and hScrib, both of which are associated with cell junction complexes. The fact that Scrib/Vart and Dlg appear to cooperate in a pathway that controls Drosophila epithelial cell growth suggests that the combined targeting of hScrib and hDlg is an important component of the biologic activity of high-risk HPV E6 proteins.

scholarly journals Recognition of high-risk HPV E6 oncoproteins by 14-3-3 proteins studied by interactomics and crystallography

2020 ◽  
Author(s):  
Gergő Gógl ◽  
Kristina Tugaeva ◽  
Pascal Eberling ◽  
Camille Kostmann ◽  
Gilles Trave ◽  
...  
Keyword(s):  
High Risk ◽  
Fluorescence Polarization ◽  
Pdz Domain ◽  
Human Papillomaviruses ◽  
Binding Motif ◽  
Hpv E6 ◽  
Sequence Variations ◽  
Hpv18 E6 ◽  
Isoform Specificity ◽  
High Risk Hpv

Abstract In tumors induced by high-risk mucosal human papillomaviruses (hrm-HPVs), HPV E6 oncoproteins inhibit apoptotic processes and sustain cell proliferation. E6 from all hrm-HPVs harbor a C-terminal short PDZ domain-binding motif (PBM), whose phosphorylation down-regulates PDZ binding but triggers E6 binding to 14-3-3 proteins. Here we classify PBMs of E6 proteins depending on their principle ability to be phosphorylated and subsequently acquire a 14-3-3-binding motif III consensus, (pS/pT)XX-COOH. Systematic competitive fluorescence polarization measurements show that the PBMs from four selected E6 oncoproteins bind all seven human 14-3-3 isoforms with distinct, wide-ranging affinities, obeying remarkable trends assigned to 14-3-3 isoform specificity and small E6 sequence variations. We crystallized the hrm-HPV18 E6 PBM bound to 14-3-3ζ, revealing a 14-3-3-motif III complex at 1.9 Å resolution. Using fluorescence polarization and crystallography, we also demonstrate that fusicoccin, a molecule that reinforces many known 14-3-3 complexes, destabilizes the 14-3-3-E6 interaction, indicating the druggability of that complex.

Comparison of Co-Presence of Epstein-Barr Virus and High-Risk Human Papillomaviruses in Colorectal Cancers in the Middle East Region

2020 ◽  
Author(s):  
Karim Nagi ◽  
Ishita Gupta ◽  
Hamda A Al-Thawadi ◽  
Ayesha Jabeen ◽  
Mohammed I. Malk ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
High Risk ◽  
Epstein Barr Virus ◽  
Human Papillomaviruses ◽  
Colorectal Cancers ◽  
Barr Virus ◽  
Human Carcinomas ◽  
Epstein Barr ◽  
Invasive Carcinomas ◽  
High Risk Hpv

Background: Several studies have shown the presence of onco viral DNA in colorectal tumor tissues. Viral infection by onco-viruses such as Human papillomaviruses (HPVs) and Epstein–Barr virus (EBV) are well-known to be involved in the onset and/or progression of numerous human carcinomas. Methods: We explored the co-presence of high-risk HPVs and EBV in a cohort of colorectal cancer samples from Lebanon (94) and Syria (102) by PCR, immunohistochemistry and tissue microarray. Results: The results of the study point out that 54% of colorectal cancer cases in Syria are positive for high-risk HPVs, while 30% of the cases in Lebanon are positive for these viruses; the most frequent high-risk HPV types in these populations are 16, 18, 31, 33 and 35. Analysis of LMP1 showed similar results in both populations; 36% of Syrian and 31% of Lebanese samples. Additionally, we report that EBV and high-risk HPVs are co-present in these samples. In Syrian samples, EBV and HPVs are co-present in 16% of the population, however, in the Lebanese samples, 20% of the cases are positive for both EBV and HPVs; their co-presence is associated with high/intermediate grade invasive carcinomas. Conclusion: These data suggest that EBV and high-risk HPVs are co-present in human colorectal cancers where they can cooperate in the progression of these cancers. Nevertheless, further studies are needed to elucidate the role of those oncoviruses in the development of human colorectal carcinomas.

scholarly journals HPV and Other Microbiota; Who’s Good and Who’s Bad: Effects of the Microbial Environment on the Development of Cervical Cancer—A Non-Systematic Review

Cells ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 714
Author(s):  
Matthias Läsche ◽  
Horst Urban ◽  
Julia Gallwas ◽  
Carsten Gründker
Keyword(s):  
Systematic Review ◽  
Cervical Cancer ◽  
High Risk ◽  
Cervical Carcinoma ◽  
Hpv Infection ◽  
Human Papillomaviruses ◽  
Inflammatory Reactions ◽  
Metabolic Signalling ◽  
Microbial Environment ◽  
High Risk Hpv

Cervical cancer is responsible for around 5% of all human cancers worldwide. It develops almost exclusively from an unsolved, persistent infection of the squamocolumnar transformation zone between the endo- and ecto-cervix with various high-risk (HR) human papillomaviruses (HPVs). The decisive turning point on the way to persistent HPV infection and malignant transformation is an immune system weakened by pathobionts and oxidative stress and an injury to the cervical mucosa, often caused by sexual activities. Through these injury and healing processes, HPV viruses, hijacking activated keratinocytes, move into the basal layers of the cervical epithelium and then continue their development towards the distal prickle cell layer (Stratum spinosum). The microbial microenvironment of the cervical tissue determines the tissue homeostasis and the integrity of the protective mucous layer through the maintenance of a healthy immune and metabolic signalling. Pathological microorganisms and the resulting dysbiosis disturb this signalling. Thus, pathological inflammatory reactions occur, which manifest the HPV infection. About 90% of all women contract an HPV infection in the course of their lives. In about 10% of cases, the virus persists and cervical intra-epithelial neoplasia (CIN) develops. Approximately 1% of women with a high-risk HPV infection incur a cervical carcinoma after 10 to 20 years. In this non-systematic review article, we summarise how the sexually and microbial mediated pathogenesis of the cervix proceeds through aberrant immune and metabolism signalling via CIN to cervical carcinoma. We show how both the virus and the cancer benefit from the same changes in the immune and metabolic environment.

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