scholarly journals The Human Papillomavirus (HPV) E6* Proteins from High-Risk, Mucosal HPVs Can Direct Degradation of Cellular Proteins in the Absence of Full-Length E6 Protein

2009 ◽  
Vol 83 (19) ◽  
pp. 9863-9874 ◽  
Author(s):  
David Pim ◽  
Vjekoslav Tomaić ◽  
Lawrence Banks
Keyword(s):  
High Risk ◽  
Tumor Suppressor ◽  
Pdz Domain ◽  
Direct Interaction ◽  
Human Papillomaviruses ◽  
Full Length ◽  
Cellular Proteins ◽  
Hpv E6 ◽  
E6 Protein ◽  
Hpv 18

ABSTRACT The E6 oncoproteins from high-risk mucosotrophic human papillomaviruses (HPVs) target a range of cellular proteins for proteasome-mediated degradation. Apart from the tumor suppressor p53 and proapoptotic Bcl-2 family member Bak, many targets contain class 1 PDZ domains and are involved in cell junction stability and signaling. The targeting mechanism is considered to function by the E6 protein acting as an adaptor molecule linking a cellular ubiquitin ligase to the target protein. In each case, whether the target is the p53 tumor suppressor or a member of the group of PDZ domain-containing targets, this mechanism relies on a direct interaction between E6 and its cellular target. This study focuses on the impact of the HPV type 18 (HPV-18) E6*I protein on the stability of Akt, Dlg, MAGI-1, MAGI-2, and Scribble. We show that HPV-18 E6* expression can downregulate the expression levels of Akt, Dlg, and Scribble in the absence of full-length HPV-18 E6 protein. The reduction in Dlg levels by E6* is independent of transcription and does not require a direct interaction between the two proteins although the proteasome pathway is involved. Further, we provide evidence that activation of certain signal transduction pathways has a profound effect on the targeting of Dlg by E6* and suggest that high-risk HPV E6 oncoproteins can target certain substrates both directly and indirectly through the E6* proteins and may cooperate in their degradation.

scholarly journals Multi-PDZ Domain Protein MUPP1 Is a Cellular Target for both Adenovirus E4-ORF1 and High-Risk Papillomavirus Type 18 E6 Oncoproteins

2000 ◽  
Vol 74 (20) ◽  
pp. 9680-9693 ◽  
Author(s):  
Siu Sylvia Lee ◽  
Britt Glaunsinger ◽  
Fiamma Mantovani ◽  
Lawrence Banks ◽  
Ronald T. Javier
Keyword(s):  
High Risk ◽  
Cellular Proliferation ◽  
Pdz Domain ◽  
Viral Proteins ◽  
Cellular Protein ◽  
Human Papillomaviruses ◽  
Binding Motif ◽  
Cellular Factor ◽  
Domain Protein ◽  
Hpv 18

ABSTRACT A general theme that has emerged from studies of DNA tumor viruses is that otherwise unrelated oncoproteins encoded by these viruses often target the same important cellular factors. Major oncogenic determinants for human adenovirus type 9 (Ad9) and high-risk human papillomaviruses (HPV) are the E4-ORF1 and E6 oncoproteins, respectively, and although otherwise unrelated, both of these viral proteins possess a functional PDZ domain-binding motif that is essential for their transforming activity and for binding to the PDZ domain-containing and putative tumor suppressor protein DLG. We report here that the PDZ domain-binding motifs of Ad9 E4-ORF1 and high-risk HPV-18 E6 also mediate binding to the widely expressed cellular factor MUPP1, a large multi-PDZ domain protein predicted to function as an adapter in signal transduction. With regard to the consequences of these interactions in cells, we showed that Ad9 E4-ORF1 aberrantly sequesters MUPP1 within the cytoplasm of cells whereas HPV-18 E6 targets this cellular protein for degradation. These effects were specific because mutant viral proteins unable to bind MUPP1 lack these activities. From these results, we propose that the multi-PDZ domain protein MUPP1 is involved in negatively regulating cellular proliferation and that the transforming activities of two different viral oncoproteins depend, in part, on their ability to inactivate this cellular factor.

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 Comparison of p53 and the PDZ domain containing protein MAGI-3 regulation by the E6 protein from high-risk human papillomaviruses

2008 ◽  
Vol 5 (1) ◽  
pp. 67 ◽  
Author(s):  
Julia Ainsworth ◽  
Miranda Thomas ◽  
Lawrence Banks ◽  
Francois Coutlee ◽  
Greg Matlashewski
Keyword(s):  
High Risk ◽  
Pdz Domain ◽  
Human Papillomaviruses ◽  
E6 Protein

scholarly journals PDZ Domain-Containing Protein NHERF-2 Is a Novel Target of Human Papillomavirus 16 (HPV-16) and HPV-18

2019 ◽  
Vol 94 (1) ◽  
Author(s):  
Nathaniel Edward Bennett Saidu ◽  
Vedrana Filić ◽  
Miranda Thomas ◽  
Vanessa Sarabia-Vega ◽  
Anamaria Đukić ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Human Papillomavirus ◽  
Tumor Suppressor ◽  
Cyclin D1 ◽  
Cellular Proliferation ◽  
Pdz Domain ◽  
Hpv 16 ◽  
Hpv E6 ◽  
Endothelial Proliferation ◽  
Hpv 18

ABSTRACT Cancer-causing human papillomavirus (HPV) E6 oncoproteins have a class I PDZ-binding motif (PBM) on their C termini, which play critical roles that are related to the HPV life cycle and HPV-induced malignancies. E6 oncoproteins use these PBMs to interact with, to target for proteasome-mediated degradation, a plethora of cellular substrates that contain PDZ domains and that are involved in the regulation of various cellular pathways. In this study, we show that both HPV-16 and HPV-18 E6 oncoproteins can interact with Na+/H+ exchange regulatory factor 2 (NHERF-2), a PDZ domain-containing protein, which among other cellular functions also behaves as a tumor suppressor regulating endothelial proliferation. The interaction between the E6 oncoproteins and NHERF-2 is PBM dependent and results in proteasome-mediated degradation of NHERF-2. We further confirmed this effect in cells derived from HPV-16- and HPV-18-positive cervical tumors, where we show that NHERF-2 protein turnover is increased in the presence of E6. Finally, our data indicate that E6-mediated NHERF-2 degradation results in p27 downregulation and cyclin D1 upregulation, leading to accelerated cellular proliferation. To our knowledge, this is the first report to demonstrate that E6 oncoproteins can stimulate cell proliferation by indirectly regulating p27 through targeting a PDZ domain-containing protein. IMPORTANCE This study links HPV-16 and HPV-18 E6 oncoproteins to the modulation of cellular proliferation. The PDZ domain-containing protein NHERF-2 is a tumor suppressor that has been shown to regulate endothelial proliferation; here, we demonstrate that NHERF-2 is targeted by HPV E6 for proteasome-mediated degradation. Interestingly, this indirectly affects p27, cyclin D1, and CDK4 protein levels and, consequently, affects cell proliferation. Hence, this study provides information that will improve our understanding of the molecular basis for HPV E6 function, and it also highlights the importance of the PDZ domain-containing protein NHERF-2 and its tumor-suppressive role in regulating cell proliferation.

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 High-Risk Human Papillomavirus E6 Oncoproteins Interact with 14-3-3ζ in a PDZ Binding Motif-Dependent Manner

2012 ◽  
Vol 87 (3) ◽  
pp. 1586-1595 ◽  
Author(s):  
Siaw Shi Boon ◽  
Lawrence Banks
Keyword(s):  
Cervical Cancer ◽  
Human Papillomavirus ◽  
High Risk ◽  
Pdz Domain ◽  
Binding Motif ◽  
Dependent Manner ◽  
Hpv E6 ◽  
Hpv Types ◽  
High Risk Hpv ◽  
Hpv 18

ABSTRACTCervical cancer develops through the combined activities of the human papillomavirus (HPV) E6 and E7 oncoproteins. A defining characteristic of E6 oncoproteins derived from cancer-causing HPV types is the presence of a PDZ binding motif (PBM) at the extreme carboxy terminus of the protein which is absent from E6 proteins derived from the so-called low-risk HPV types. Within this PBM is also a protein kinase A (PKA) phospho-acceptor site, which is thought to negatively regulate the association of E6 with its PDZ domain-containing substrates. We can now show that phosphorylation of E6 by PKA and/or AKT confers the ability to interact with 14-3-3ζ. The interaction is direct and specific for the high-risk HPV E6 oncoproteins, although there are significant differences in the efficiencies with which HPV-16, HPV-18, and HPV-31 E6 oncoproteins can associate with 14-3-3ζ; this correlates directly with their respective susceptibilities to phosphorylation by PKA and/or AKT. We demonstrate here that the interaction between E6 and 14-3-3ζ also requires integrity of the E6 PBM, and downregulation of 14-3-3ζ results in a marked reduction in the levels of HPV-18 E6 expression in HeLa cells. Using phospho-specific anti-E6 antibodies, we also demonstrate significant levels of E6 phosphorylationin vivo. These studies redefine the potential relevance of the E6 PBM in the development of cervical cancer, suggesting that interaction with 14-3-3ζ, as well as the more well-established interactions with PDZ domain-containing substrates, is likely to be responsible for the biological activities attributed to this region of the high-risk HPV E6 oncoproteins.

scholarly journals A conserved C-terminal sequence of high-risk cutaneous beta-human papillomavirus E6 proteins alters localization and signalling of β1-integrin to promote cell migration

2014 ◽  
Vol 95 (1) ◽  
pp. 123-134 ◽  
Author(s):  
Amy Holloway ◽  
Alan Storey
Keyword(s):  
Cell Migration ◽  
High Risk ◽  
Molecular Mechanisms ◽  
Pdz Domain ◽  
Point Mutations ◽  
Transgenic Animals ◽  
Human Keratinocytes ◽  
Human Papillomaviruses ◽  
Hpv E6 ◽  
Hpv Types

Beta-human papillomaviruses (β-HPV) infect cutaneous epithelia, and accumulating evidence suggests that the virus may act as a co-factor with UV-induced DNA damage in the development and progression of non-melanoma skin cancer, although the molecular mechanisms involved are poorly understood. The E6 protein of cutaneous β-HPV types encodes functions consistent with a role in tumorigenesis, and E6 expression can result in papilloma formation in transgenic animals. The E6 proteins of high-risk α-HPV types, which are associated with the development of anogenital cancers, have a conserved 4 aa motif at their extreme C terminus that binds to specific PDZ domain-containing proteins to promote cell invasion. Likewise, the high-risk β-HPVs HPV5 and HPV8 E6 proteins also share a conserved C-terminal motif, but this is markedly different from that of α-HPV types, implying functional differences. Using binding and functional studies, we have shown that β-HPV E6 proteins target β1-integrin using this C-terminal motif. E6 expression reduced membrane localization of β1-integrin, but increased overall levels of β1-integrin protein and its downstream effector focal adhesion kinase in human keratinocytes. Altered β1-integrin localization due to E6 expression was associated with actin cytoskeleton rearrangement and increased cell migration that was abolished by point mutations in the C-terminal motif of E6. We concluded that modulation of β1-integrin signalling by E6 proteins may contribute towards the pathogenicity of these β-HPV types.

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.

scholarly journals Complementation of a p300/CBP defective-binding mutant of adenovirus E1a by human papillomavirus E6 proteins

2002 ◽  
Vol 83 (4) ◽  
pp. 829-833 ◽  
Author(s):  
Agnieszka Bernat ◽  
Paola Massimi ◽  
Lawrence Banks
Keyword(s):  
Human Papillomavirus ◽  
High Risk ◽  
Cell Transformation ◽  
Deficient Mutant ◽  
Hpv 16 ◽  
Adenovirus E1a ◽  
Human Papillomavirus Type 16 ◽  
Hpv E6 ◽  
E6 Protein ◽  
Hpv 18

Previous studies have shown that the human papillomavirus type 16 (HPV-16) E6 protein binds to p300/CBP and abrogates its transcriptional co-activator function. However, there is little information on the biological consequences of this interaction and discrepancy as to whether the interaction is high-risk E6 specific or not. We performed a series of studies to compare the interactions of HPV-18 and HPV-11 E6 with p300, and showed that both high- and low- risk E6 proteins bind p300. In addition, using a transformation-deficient mutant of adenovirus E1a, which cannot interact with p300, we demonstrated that HPV-16, HPV-18 and, to a lesser extent, HPV-11 E6, can complement this mutant in cell transformation assays. In contrast, a mutant of HPV-16 E6 which does not bind p300 failed to rescue the E1a mutant. These results suggest that the E6–p300 interaction may be important for the ability of HPV E6 to contribute towards cell transformation.

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