1
|
Javorsky A, Humbert PO, Kvansakul M. Viral manipulation of cell polarity signalling. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2023; 1870:119536. [PMID: 37437846 DOI: 10.1016/j.bbamcr.2023.119536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 06/24/2023] [Accepted: 07/04/2023] [Indexed: 07/14/2023]
Abstract
Cell polarity refers to the asymmetric distribution of biomacromolecules that enable the correct orientation of a cell in a particular direction. It is thus an essential component for appropriate tissue development and function. Viral infections can lead to dysregulation of polarity. This is associated with a poor prognosis due to viral interference with core cell polarity regulatory scaffolding proteins that often feature PDZ (PSD-95, DLG, and ZO-1) domains including Scrib, Dlg, Pals1, PatJ, Par3 and Par6. PDZ domains are also promiscuous, binding to several different partners through their C-terminal region which contain PDZ-binding motifs (PBM). Numerous viruses encode viral effector proteins that target cell polarity regulators for their benefit and include papillomaviruses, flaviviruses and coronaviruses. A better understanding of the mechanisms of action utilised by viral effector proteins to subvert host cell polarity sigalling will provide avenues for future therapeutic intervention, while at the same time enhance our understanding of cell polarity regulation and its role tissue homeostasis.
Collapse
Affiliation(s)
- Airah Javorsky
- Department of Biochemistry & Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria 3086, Australia
| | - Patrick O Humbert
- Department of Biochemistry & Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria 3086, Australia; Research Centre for Molecular Cancer Prevention, La Trobe University, Melbourne, Victoria 3086, Australia; Department of Biochemistry & Pharmacology, University of Melbourne, Melbourne, Victoria 3010, Australia; Department of Clinical Pathology, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Marc Kvansakul
- Department of Biochemistry & Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria 3086, Australia; Research Centre for Molecular Cancer Prevention, La Trobe University, Melbourne, Victoria 3086, Australia.
| |
Collapse
|
2
|
Viral subversion of the cell polarity regulator Scribble. Biochem Soc Trans 2023; 51:415-426. [PMID: 36606695 PMCID: PMC9987997 DOI: 10.1042/bst20221067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 12/08/2022] [Accepted: 12/12/2022] [Indexed: 01/07/2023]
Abstract
Scribble is a scaffolding protein that regulates key events such as cell polarity, tumorigenesis and neuronal signalling. Scribble belongs to the LAP family which comprise of 16 Leucine Rich Repeats (LRR) at the N-terminus, two LAP Specific Domains (LAPSD) and four PSD-95/Discs-large/ZO-1 (PDZ) domains at the C-terminus. The four PDZ domains have been shown to be key for a range of protein-protein interactions and have been identified to be crucial mediators for the vast majority of Scribble interactions, particularly via PDZ Binding Motifs (PBMs) often found at the C-terminus of interacting proteins. Dysregulation of Scribble is associated with poor prognosis in viral infections due to subversion of multiple cell signalling pathways by viral effector proteins. Here, we review the molecular details of the interplay between Scribble and viral effector proteins that provide insight into the potential modes of regulation of Scribble mediated polarity signalling.
Collapse
|
3
|
Stewart BZ, Caria S, Humbert PO, Kvansakul M. Structural analysis of human papillomavirus E6 interactions with Scribble PDZ domains. FEBS J 2023. [PMID: 36609831 DOI: 10.1111/febs.16718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 12/16/2022] [Accepted: 01/05/2022] [Indexed: 01/08/2023]
Abstract
The cell polarity regulator Scribble has been shown to be a critical regulator of the establishment and development of tissue architecture, and its dysregulation promotes or suppresses tumour development in a context-dependent manner. Scribble activity is subverted by numerous viruses. This includes human papillomaviruses (HPVs), who target Scribble via the E6 protein. Binding of E6 from high-risk HPV strains to Scribble via a C-terminal PDZ-binding motif leads to Scribble degradation in vivo. However, the precise molecular basis for Scribble-E6 interactions remains to be defined. We now show that Scribble PDZ1 and PDZ3 are the major interactors of HPV E6 from multiple high-risk strains, with each E6 protein displaying a unique interaction profile. We then determined crystal structures of Scribble PDZ1 and PDZ3 domains in complex with the PDZ-binding motif (PBM) motifs of E6 from HPV strains 16, 18 and 66. Our findings reveal distinct interaction patterns for each E6 PBM motif from a given HPV strain, suggesting that a complex molecular interplay exists that underpins the overt Scribble-HPV E6 interaction and controls E6 carcinogenic potential.
Collapse
Affiliation(s)
- Bryce Z Stewart
- Department of Biochemistry & Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, Australia
| | - Sofia Caria
- Department of Biochemistry & Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, Australia
| | - Patrick O Humbert
- Department of Biochemistry & Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, Australia.,Department of Biochemistry & Pharmacology, University of Melbourne, VIC, Australia.,Department of Clinical Pathology, University of Melbourne, VIC, 3010, Australia
| | - Marc Kvansakul
- Department of Biochemistry & Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, VIC, Australia
| |
Collapse
|
4
|
Kajitani N, Schwartz S. The role of RNA-binding proteins in the processing of mRNAs produced by carcinogenic papillomaviruses. Semin Cancer Biol 2022; 86:482-496. [PMID: 35181475 DOI: 10.1016/j.semcancer.2022.02.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 02/10/2022] [Accepted: 02/11/2022] [Indexed: 02/08/2023]
Abstract
Human papillomaviruses (HPV) are epitheliotropic DNA tumor viruses that are prevalent in the human population. A subset of the HPVs termed high-risk HPVs (HR-HPVs) are causative agents of anogenital cancers and head-and-neck cancers. Cancer is the result of persistent high-risk HPV infections that have not been cleared by the immune system of the host. These infections are characterized by dysregulated HPV gene expression, in particular constitutive high expression of the HPV E6 and E7 oncogenes and absence of the highly immunogenic viral L1 and L2 capsid proteins. HPVs make extensive use of alternative mRNA splicing to express its genes and are therefore highly dependent on cellular RNA-binding proteins for proper gene expression. Levels of RNA-binding proteins are altered in HPV-containing premalignant cervical lesions and in cervical cancer. Here we review our current knowledge of RNA-binding proteins that control HPV gene expression. We focus on RNA-binding proteins that control expression of the E6 and E7 oncogenes since they initiate and drive development of cancer and on the immunogenic L1 and L2 proteins as there silencing may contribute to immune evasion during carcinogenesis. Furthermore, cellular RNA-binding proteins are essential for HPV gene expression and as such may be targets for therapy to HPV infections and HPV-driven cancers.
Collapse
Affiliation(s)
- Naoko Kajitani
- Department of Medical Biochemistry and Microbiology (IMBIM), Uppsala University, BMC-B9, 751 23, Uppsala, Sweden; Department of Laboratory Medicine, Lund University, BMC-B13, 221 84, Lund, Sweden
| | - Stefan Schwartz
- Department of Medical Biochemistry and Microbiology (IMBIM), Uppsala University, BMC-B9, 751 23, Uppsala, Sweden; Department of Laboratory Medicine, Lund University, BMC-B13, 221 84, Lund, Sweden.
| |
Collapse
|
5
|
Thomas M, Banks L. The biology of papillomavirus PDZ associations: what do they offer papillomaviruses? Curr Opin Virol 2021; 51:119-126. [PMID: 34655911 DOI: 10.1016/j.coviro.2021.09.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 09/10/2021] [Accepted: 09/21/2021] [Indexed: 01/05/2023]
Abstract
The high-risk α-type papillomaviruses have a C-terminal PDZ-binding motif (PBM) on one of the two major oncoproteins E6 or E7; the vast majority on E6. The PBM is essential for the high-risk HPV life cycle, for episomal maintenance of the virus genome, and for maintaining the mitotic stability of the infected cell. The question is why only these viruses have PBMs - are there specific constraints imposed by the mucosal epithelium in which these viruses replicate? However the low-risk α-HPVs, such as HPV-6 and HPV-11 replicate extremely efficiently without a PBM, while viruses of the alpha8 group, such as HPV-40, replicate well with a very primitive PBM. So what does PDZ-binding capacity contribute to the fitness of the virus?
Collapse
Affiliation(s)
- Miranda Thomas
- ICGEB, AREA Science Park, Padriciano 99, 34149, Trieste, Italy.
| | - Lawrence Banks
- ICGEB, AREA Science Park, Padriciano 99, 34149, Trieste, Italy
| |
Collapse
|
6
|
Basukala O, Banks L. The Not-So-Good, the Bad and the Ugly: HPV E5, E6 and E7 Oncoproteins in the Orchestration of Carcinogenesis. Viruses 2021; 13:1892. [PMID: 34696321 PMCID: PMC8541208 DOI: 10.3390/v13101892] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 09/13/2021] [Accepted: 09/14/2021] [Indexed: 12/15/2022] Open
Abstract
Infection with HPV starts with the access of the viral particles to basal cells in the epidermis, potentially via microtraumas to the skin. The basal cells are able to keep away these pathogens in normal circumstances through a robust immune response from the host, as HPV infections are, in general, cleared within 2 to 3 weeks. However, the rare instances of persistent infection and/or in cases where the host immune system is compromised are major risk factors for the development of lesions potentially leading to malignancy. Evolutionarily, obligatory pathogens such as HPVs would not be expected to risk exposing the host to lethal cancer, as this would entail challenging their own life cycle, but infection with these viruses is highly correlated with cancer and malignancy-as in cancer of the cervix, which is almost always associated with these viruses. Despite this key associative cause and the availability of very effective vaccines against these viruses, therapeutic interventions against HPV-induced cancers are still a challenge, indicating the need for focused translational research. In this review, we will consider the key roles that the viral proteins play in driving the host cells to carcinogenesis, mainly focusing on events orchestrated by early proteins E5, E6 and E7-the not-so-good, the bad and the ugly-and discuss and summarize the major events that lead to these viruses mechanistically corrupting cellular homeostasis, giving rise to cancer and malignancy.
Collapse
Affiliation(s)
| | - Lawrence Banks
- Tumour Virology Laboratory, International Centre for Genetic Engineering and Biotechnology, Padriciano 99, I-34149 Trieste, Italy;
| |
Collapse
|
7
|
Vats A, Trejo-Cerro O, Thomas M, Banks L. Human papillomavirus E6 and E7: What remains? Tumour Virus Res 2021; 11:200213. [PMID: 33716206 PMCID: PMC7972986 DOI: 10.1016/j.tvr.2021.200213] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 01/29/2021] [Accepted: 02/01/2021] [Indexed: 12/12/2022] Open
Abstract
Decades of research on the human papillomavirus oncogenes, E6 and E7, have given us huge amounts of data on their expression, functions and structures. We know much about the very many cellular proteins and pathways that they influence in one way or another. However, much of this information is quite discrete, referring to one activity examined under one condition. It is now time to join the dots to try to understand a larger picture: how, where and when do all these interactions occur... and why? Examining these questions will also show how many of the yet obscure cellular processes work together for cellular and tissue homeostasis in health and disease.
Collapse
Affiliation(s)
- Arushi Vats
- Tumour Virology Group, ICGEB, AREA Science Park, Trieste, 34149, Italy
| | - Oscar Trejo-Cerro
- Tumour Virology Group, ICGEB, AREA Science Park, Trieste, 34149, Italy
| | - Miranda Thomas
- Tumour Virology Group, ICGEB, AREA Science Park, Trieste, 34149, Italy.
| | - Lawrence Banks
- Tumour Virology Group, ICGEB, AREA Science Park, Trieste, 34149, Italy
| |
Collapse
|
8
|
High-Risk Human Papillomaviruses and DNA Repair. Recent Results Cancer Res 2020. [PMID: 33200365 DOI: 10.1007/978-3-030-57362-1_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/19/2023]
Abstract
Human papillomaviruses (HPVs) are small DNA viruses that infect basal epithelial cells and are the causative agents of cervical, anogenital, as well as oral cancers. High-risk HPVs are responsible for nearly half of all virally induced cancers. Viral replication and amplification are intimately linked to the stratified epithelium differentiation program. The E6 and E7 proteins contribute to the development of cancers in HPV positive individuals by hijacking cellular processes and causing genetic instability. This genetic instability induces a robust DNA damage response and activating both ATM and ATR repair pathways. These pathways are critical for the productive replication of high-risk HPVs, and understanding how they contribute to the viral life cycle can provide important insights into HPV's role in oncogenesis. This review will discuss the role that differentiation and the DNA damage responses play in productive replication of high-risk HPVs as well as in the development of cancer.
Collapse
|
9
|
Shiraz A, Crawford R, Egawa N, Griffin H, Doorbar J. The early detection of cervical cancer. The current and changing landscape of cervical disease detection. Cytopathology 2020; 31:258-270. [PMID: 32301535 DOI: 10.1111/cyt.12835] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 03/09/2020] [Accepted: 03/23/2020] [Indexed: 01/04/2023]
Abstract
Cervical cancer prevention has undergone dramatic changes over the past decade. With the introduction of human papillomavirus (HPV) vaccination, some countries have seen a dramatic decline in HPV-mediated cervical disease. However, widespread implementation has been limited by economic considerations and the varying healthcare priorities of different countries, as well as by vaccine availability and, in some instances, vaccine hesitancy amongst the population/government. In this environment, it is clear that cervical screening will retain a critical role in the prevention of cervical cancer and will in due course need to adapt to the changing incidence of HPV-associated neoplasia. Cervical screening has, for many years, been performed using Papanicolaou staining of cytology samples. As our understanding of the role of HPV in cervical cancer progression has advanced, and with the availability of sensitive detection systems, cervical screening now incorporates HPV testing. Although such tests improve disease detection, they are not specific, and cannot discriminate high-grade from low-grade disease. This has necessitated the development of effective triage approaches to stratify HPV-positive women according to their risk of cancer progression. Although cytology triage remains the mainstay of screening, novel strategies under evaluation include DNA methylation, biomarker detection and the incorporation of artificial intelligence systems to detect cervical abnormalities. These tests, which can be partially anchored in a molecular understanding of HPV pathogenesis, will enhance the sensitivity of disease detection and improve patient outcomes. This review will provide insight on these innovative methodologies while explaining their scientific basis drawing from our understanding of HPV tumour biology.
Collapse
Affiliation(s)
- Aslam Shiraz
- Department of Pathology, University of Cambridge, Cambridge, UK
- Department of Gynae-Oncology, Addenbrookes Hospital, Cambridge, UK
| | - Robin Crawford
- Department of Gynae-Oncology, Addenbrookes Hospital, Cambridge, UK
| | - Nagayasu Egawa
- Department of Pathology, University of Cambridge, Cambridge, UK
| | - Heather Griffin
- Department of Pathology, University of Cambridge, Cambridge, UK
| | - John Doorbar
- Department of Pathology, University of Cambridge, Cambridge, UK
| |
Collapse
|
10
|
Dizanzo MP, Marziali F, Brunet Avalos C, Bugnon Valdano M, Leiva S, Cavatorta AL, Gardiol D. HPV E6 and E7 oncoproteins cooperatively alter the expression of Disc Large 1 polarity protein in epithelial cells. BMC Cancer 2020; 20:293. [PMID: 32264889 PMCID: PMC7137215 DOI: 10.1186/s12885-020-06778-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Accepted: 03/23/2020] [Indexed: 11/30/2022] Open
Abstract
Background Persistent infection with high-risk Human Papillomavirus (HPVs) is associated with the development of cervical cancer. The transforming capacity of these viruses relies on the cooperative action of the E6 and E7 viral oncoproteins. Among the oncogenic activities of E6, the interaction and interference with cell polarity PDZ proteins have been well established. One of the most characterized PDZ targets of HPV E6 is human Disc large 1 (DLG1), a scaffolding protein involved in the control of cell polarity and proliferation. Interestingly, in cervical squamous intraepithelial lesions, alterations in DLG1 expression were observed in association to tumour progression. Moreover, the expression of both HPV E6 and E7 proteins may be responsible for the changes in DLG1 abundance and cell localization observed in the HPV-associated lesions. Methods Due to the relevance of DLG1 deregulation in tumour development, we have performed an in-depth investigation of the expression of DLG1 in the presence of the HPV oncoproteins in epithelial cultured cells. The effects of HPV E6 and E7 proteins on DLG1 abundance and subcellular localization were assessed by western blot and confocal fluorescence microscopy, respectively. Results We demonstrated that the relative abundance of HPV-18 E6 and DLG1 is a key factor that contributes to defining the expression abundance of both proteins. We also show here that a high expression level of DLG1 may negatively affect HPV-18 E6 nuclear expression. Moreover, the co-expression of HPV-18 E6 and E7 produces a striking effect on DLG1 subcellular localization and a co-distribution in the cytoplasmic region. Interestingly, HPV-18 E7 is also able to increase DLG1 levels, likely by rescuing it from the E6-mediated proteasomal degradation. Conclusions In general, the data suggest that HPV-18 E6 and E7 may have opposing activities in regards to the regulation of DLG1 levels and may cooperatively contribute to its subcellular redistribution in the HPV context. These findings constitute a step forward in understanding the differential expression of DLG1 during tumour progression in an HPV-associated model.
Collapse
Affiliation(s)
- María Paula Dizanzo
- Instituto de Biología Molecular y Celular de Rosario-CONICET, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000, Rosario, Argentina
| | - Federico Marziali
- Instituto de Biología Molecular y Celular de Rosario-CONICET, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000, Rosario, Argentina
| | - Clarisse Brunet Avalos
- Instituto de Biología Molecular y Celular de Rosario-CONICET, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000, Rosario, Argentina
| | - Marina Bugnon Valdano
- Instituto de Biología Molecular y Celular de Rosario-CONICET, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000, Rosario, Argentina
| | - Santiago Leiva
- Instituto de Biología Molecular y Celular de Rosario-CONICET, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000, Rosario, Argentina
| | - Ana Laura Cavatorta
- Instituto de Biología Molecular y Celular de Rosario-CONICET, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000, Rosario, Argentina
| | - Daniela Gardiol
- Instituto de Biología Molecular y Celular de Rosario-CONICET, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000, Rosario, Argentina.
| |
Collapse
|
11
|
PDZ Domain-Containing Protein NHERF-2 Is a Novel Target of Human Papillomavirus 16 (HPV-16) and HPV-18. J Virol 2019; 94:JVI.00663-19. [PMID: 31597772 DOI: 10.1128/jvi.00663-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Accepted: 09/11/2019] [Indexed: 01/02/2023] Open
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.
Collapse
|
12
|
Young JM, Zine El Abidine A, Gómez-Martinez RA, Ozbun MA. The Known and Potential Intersections of Rab-GTPases in Human Papillomavirus Infections. Front Cell Dev Biol 2019; 7:139. [PMID: 31475144 PMCID: PMC6702953 DOI: 10.3389/fcell.2019.00139] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Accepted: 07/09/2019] [Indexed: 12/16/2022] Open
Abstract
Papillomaviruses (PVs) were the first viruses recognized to cause tumors and cancers in mammalian hosts by Shope, nearly a century ago (Shope and Hurst, 1933). Over 40 years ago, zur Hausen (1976) first proposed that human papillomaviruses (HPVs) played a role in cervical cancer; in 2008, he shared the Nobel Prize in Medicine for his abundant contributions demonstrating the etiology of HPVs in genital cancers. Despite effective vaccines and screening, HPV infection and morbidity remain a significant worldwide burden, with HPV infections and HPV-related cancers expected increase through 2040. Although HPVs have long-recognized roles in tumorigenesis and cancers, our understanding of the molecular mechanisms by which these viruses interact with cells and usurp cellular processes to initiate infections and produce progeny virions is limited. This is due to longstanding challenges in both obtaining well-characterized infectious virus stocks and modeling tissue-based infection and the replicative cycles in vitro. In the last 20 years, the development of methods to produce virus-like particles (VLPs) and pseudovirions (PsV) along with more physiologically relevant cell- and tissue-based models has facilitated progress in this area. However, many questions regarding HPV infection remain difficult to address experimentally and are, thus, unanswered. Although an obligatory cellular uptake receptor has yet to be identified for any PV species, Rab-GTPases contribute to HPV uptake and transport of viral genomes toward the nucleus. Here, we provide a general overview of the current HPV infection paradigm, the epithelial differentiation-dependent HPV replicative cycle, and review the specifics of how HPVs usurp Rab-related functions during infectious entry. We also suggest other potential interactions based on how HPVs alter cellular activities to complete their replicative-cycle in differentiating epithelium. Understanding how HPVs interface with Rab functions during their complex replicative cycle may provide insight for the development of therapeutic interventions, as current viral counter-measures are solely prophylactic and therapies for HPV-positive individuals remain archaic and limited.
Collapse
Affiliation(s)
- Jesse M. Young
- Department of Molecular Genetics and Microbiology, University of New Mexico School of Medicine, UNM Comprehensive Cancer Center, Albuquerque, NM, United States
| | - Amira Zine El Abidine
- Department of Molecular Genetics and Microbiology, University of New Mexico School of Medicine, UNM Comprehensive Cancer Center, Albuquerque, NM, United States
| | - Ricardo A. Gómez-Martinez
- Department of Molecular Genetics and Microbiology, University of New Mexico School of Medicine, UNM Comprehensive Cancer Center, Albuquerque, NM, United States
- Department of Obstetrics & Gynecology, University of New Mexico School of Medicine, UNM Comprehensive Cancer Center, Albuquerque, NM, United States
| | - Michelle A. Ozbun
- Department of Molecular Genetics and Microbiology, University of New Mexico School of Medicine, UNM Comprehensive Cancer Center, Albuquerque, NM, United States
- Department of Obstetrics & Gynecology, University of New Mexico School of Medicine, UNM Comprehensive Cancer Center, Albuquerque, NM, United States
| |
Collapse
|
13
|
Murakami I, Egawa N, Griffin H, Yin W, Kranjec C, Nakahara T, Kiyono T, Doorbar J. Roles for E1-independent replication and E6-mediated p53 degradation during low-risk and high-risk human papillomavirus genome maintenance. PLoS Pathog 2019; 15:e1007755. [PMID: 31083694 PMCID: PMC6544336 DOI: 10.1371/journal.ppat.1007755] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 05/31/2019] [Accepted: 04/08/2019] [Indexed: 01/08/2023] Open
Abstract
Human papillomaviruses (HPV) have genotype-specific disease associations, with high-risk alpha types causing at least 5% of all human cancers. Despite these conspicuous differences, our data show that high- and low- risk HPV types use similar approaches for genome maintenance and persistence. During the maintenance phase, viral episomes and the host cell genome are replicated synchronously, and for both the high- and low-risk HPV types, the E1 viral helicase is non-essential. During virus genome amplification, replication switches from an E1-independent to an E1-dependent mode, which can uncouple viral DNA replication from that of the host cell. It appears that the viral E2 protein, but not E6 and E7, is required for the synchronous maintenance-replication of both the high and the low-risk HPV types. Interestingly, the ability of the high-risk E6 protein to mediate the proteosomal degradation of p53 and to inhibit keratinocyte differentiation, was also seen with low-risk HPV E6, but in this case was regulated by cell density and the level of viral gene expression. This allows low-risk E6 to support genome amplification, while limiting the extent of E6-mediated cell proliferation during synchronous genome maintenance. Both high and low-risk E7s could facilitate cell cycle re-entry in differentiating cells and support E1-dependent replication. Despite the well-established differences in the viral pathogenesis and cancer risk, it appears that low- and high-risk HPV types use fundamentally similar molecular strategies to maintain their genomes, albeit with important differences in their regulatory control. Our results provide new insights into the regulation of high and low-risk HPV genome replication and persistence in the epithelial basal and parabasal cells layers. Understanding the minimum requirement for viral genome persistence will facilitate the development of therapeutic strategies for clearance.
Collapse
Affiliation(s)
- Isao Murakami
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, United Kingdom
- Department of Obstetrics and Gynecology, Keio University School of Medicine, Shinjuku-ku, Tokyo, Japan
| | - Nagayasu Egawa
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, United Kingdom
| | - Heather Griffin
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, United Kingdom
| | - Wen Yin
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, United Kingdom
| | - Christian Kranjec
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, United Kingdom
| | - Tomomi Nakahara
- Division of Carcinogenesis and Cancer Prevention, National Cancer Center Research Institute, Tokyo, Japan
| | - Tohru Kiyono
- Division of Carcinogenesis and Cancer Prevention, National Cancer Center Research Institute, Tokyo, Japan
| | - John Doorbar
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, United Kingdom
| |
Collapse
|
14
|
Sarabia-Vega V, Banks L. Acquisition of a phospho-acceptor site enhances HPV E6 PDZ-binding motif functional promiscuity. J Gen Virol 2019; 101:954-962. [PMID: 30810519 DOI: 10.1099/jgv.0.001236] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
All cancer-causing human papillomavirus (HPV) E6 oncoproteins have a C-terminal PDZ-binding motif (PBM), which correlates with oncogenic potential. Nonetheless, several HPVs with little or no oncogenic potential also have an E6 PBM, with minor sequence differences affecting PDZ protein selectivity. Furthermore, certain HPV types have a phospho-acceptor site embedded within the PBM. We therefore compared HPV-18, HPV-66 and HPV-40 E6 proteins to examine the possible link between the ability to target multiple PDZ proteins and the acquisition of a phospho-acceptor site. The mutation of essential residues in HPV-18E6 reduces its phosphorylation, and fewer PDZ substrates are bound. In contrast, the generation of consensus phospho-acceptor sites in HPV-66 and HPV-40 E6 PBMs increases the PDZ proteins recognized. Thus, although phosphorylation of the E6 PBM and PDZ protein recognition are mutually exclusive, they are closely linked, with the acquisition of a phospho-acceptor site also contributing to an expansion in the number of PDZ proteins bound.
Collapse
Affiliation(s)
- Vanessa Sarabia-Vega
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, I-34149 Trieste, Italy
| | - Lawrence Banks
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, I-34149 Trieste, Italy
| |
Collapse
|
15
|
Thomas M, Banks L. Upsetting the Balance: When Viruses Manipulate Cell Polarity Control. J Mol Biol 2018; 430:3481-3503. [PMID: 29680664 PMCID: PMC7094317 DOI: 10.1016/j.jmb.2018.04.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 04/12/2018] [Accepted: 04/14/2018] [Indexed: 12/20/2022]
Abstract
The central importance of cell polarity control is emphasized by the frequency with which it is targeted by many diverse viruses. It is clear that in targeting key polarity control proteins, viruses affect not only host cell polarity, but also influence many cellular processes, including transcription, replication, and innate and acquired immunity. Examination of the interactions of different virus proteins with the cell and its polarity controls during the virus life cycles, and in virally-induced cell transformation shows ever more clearly how intimately all cellular processes are linked to the control of cell polarity.
Collapse
|
16
|
Mitotic control of human papillomavirus genome-containing cells is regulated by the function of the PDZ-binding motif of the E6 oncoprotein. Oncotarget 2017; 8:19491-19506. [PMID: 28061478 PMCID: PMC5386700 DOI: 10.18632/oncotarget.14469] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 12/18/2016] [Indexed: 01/04/2023] Open
Abstract
The function of a conserved PDS95/DLG1/ZO1 (PDZ) binding motif (E6 PBM) at the C-termini of E6 oncoproteins of high-risk human papillomavirus (HPV) types contributes to the development of HPV-associated malignancies. Here, using a primary human keratinocyte-based model of the high-risk HPV18 life cycle, we identify a novel link between the E6 PBM and mitotic stability. In cultures containing a mutant genome in which the E6 PBM was deleted there was an increase in the frequency of abnormal mitoses, including multinucleation, compared to cells harboring the wild type HPV18 genome. The loss of the E6 PBM was associated with a significant increase in the frequency of mitotic spindle defects associated with anaphase and telophase. Furthermore, cells carrying this mutant genome had increased chromosome segregation defects and they also exhibited greater levels of genomic instability, as shown by an elevated level of centromere-positive micronuclei. In wild type HPV18 genome-containing organotypic cultures, the majority of mitotic cells reside in the suprabasal layers, in keeping with the hyperplastic morphology of the structures. However, in mutant genome-containing structures a greater proportion of mitotic cells were retained in the basal layer, which were often of undefined polarity, thus correlating with their reduced thickness. We conclude that the ability of E6 to target cellular PDZ proteins plays a critical role in maintaining mitotic stability of HPV infected cells, ensuring stable episome persistence and vegetative amplification.
Collapse
|
17
|
Moody C. Mechanisms by which HPV Induces a Replication Competent Environment in Differentiating Keratinocytes. Viruses 2017; 9:v9090261. [PMID: 28925973 PMCID: PMC5618027 DOI: 10.3390/v9090261] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 09/14/2017] [Accepted: 09/15/2017] [Indexed: 12/15/2022] Open
Abstract
Human papillomaviruses (HPV) are the causative agents of cervical cancer and are also associated with other genital malignancies, as well as an increasing number of head and neck cancers. HPVs have evolved their life cycle to contend with the different cell states found in the stratified epithelium. Initial infection and viral genome maintenance occurs in the proliferating basal cells of the stratified epithelium, where cellular replication machinery is abundant. However, the productive phase of the viral life cycle, including productive replication, late gene expression and virion production, occurs upon epithelial differentiation, in cells that normally exit the cell cycle. This review outlines how HPV interfaces with specific cellular signaling pathways and factors to provide a replication-competent environment in differentiating cells.
Collapse
Affiliation(s)
- Cary Moody
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
| |
Collapse
|
18
|
Marx B, Miller-Lazic D, Doorbar J, Majewski S, Hofmann K, Hufbauer M, Akgül B. HPV8-E6 Interferes with Syntenin-2 Expression through Deregulation of Differentiation, Methylation and Phosphatidylinositide-Kinase Dependent Mechanisms. Front Microbiol 2017; 8:1724. [PMID: 28970821 PMCID: PMC5609557 DOI: 10.3389/fmicb.2017.01724] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 08/24/2017] [Indexed: 12/01/2022] Open
Abstract
The E6 oncoproteins of high-risk human papillomaviruses (HPV) of genus alpha contain a short peptide sequence at the carboxy-terminus, the PDZ binding domain, with which they interact with the corresponding PDZ domain of cellular proteins. Interestingly, E6 proteins from papillomaviruses of genus beta (betaPV) do not encode a comparable PDZ binding domain. Irrespective of this fact, we previously showed that the E6 protein of HPV8 (betaPV type) could circumvent this deficit by targeting the PDZ protein Syntenin-2 through transcriptional repression (Lazic et al., 2012). Despite its high binding affinity to phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2), very little is known about Syntenin-2. This study aimed to extend the knowledge on Syntenin-2 and how its expression is controlled. We now identified that Syntenin-2 is expressed at high levels in differentiating and in lower amounts in keratinocytes cultured in serum-free media containing low calcium concentration. HPV8-E6 led to a further reduction of Syntenin-2 expression only in cells cultured in low calcium. In the skin of patients suffering from Epidermodysplasia verruciformis, who are predisposed to betaPV infection, Syntenin-2 was expressed in differentiating keratinocytes of non-lesional skin, but was absent in virus positive squamous tumors. Using 5-Aza-2′-deoxycytidine, which causes DNA demethylation, Syntenin-2 transcription was profoundly activated and fully restored in the absence and presence of HPV8-E6, implicating that E6 mediated repression of Syntenin-2 transcription is due to promoter hypermethylation. Since Syntenin-2 binds to PI(4,5)P2, we further tested whether the PI(4,5)P2 metabolic pathway might govern Syntenin-2 expression. PI(4,5)P2 is generated by the activity of phosphatidylinositol-4-phosphate-5-kinase type I (PIP5KI) or phosphatidylinositol-5-phosphate-4-kinase type II (PIP4KII) isoforms α, β and γ. Phosphatidylinositide kinases have recently been identified as regulators of gene transcription. Surprisingly, transfection of siRNAs directed against PIP5KI and PIP4KII resulted in higher Syntenin-2 expression with the highest effect mediated by siPIP5KIα. HPV8-E6 was able to counteract siPIP4KIIα, siPIP4KIIβ and siPIP5KIγ mediated Syntenin-2 re-expression but not siPIP5KIα. Finally, we identified Syntenin-2 as a key factor regulating PIP5KIα expression. Collectively, our data demonstrates that Syntenin-2 is regulated through multiple mechanisms and that downregulation of Syntenin-2 expression may contribute to E6 mediated dedifferentiation of infected skin cells.
Collapse
Affiliation(s)
- Benjamin Marx
- Institute of Virology, University of CologneCologne, Germany
| | | | - John Doorbar
- Department of Pathology, University of CambridgeCambridge, United Kingdom
| | - Slawomir Majewski
- Department of Dermatology and Venereology, Medical University of WarsawWarsaw, Poland
| | - Kay Hofmann
- Institute for Genetics, University of CologneCologne, Germany
| | - Martin Hufbauer
- Institute of Virology, University of CologneCologne, Germany
| | - Baki Akgül
- Institute of Virology, University of CologneCologne, Germany
| |
Collapse
|
19
|
The human papillomavirus replication cycle, and its links to cancer progression: a comprehensive review. Clin Sci (Lond) 2017; 131:2201-2221. [DOI: 10.1042/cs20160786] [Citation(s) in RCA: 156] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 06/26/2017] [Accepted: 07/03/2017] [Indexed: 12/21/2022]
Abstract
HPVs (human papillomaviruses) infect epithelial cells and their replication cycle is intimately linked to epithelial differentiation. There are over 200 different HPV genotypes identified to date and each displays a strict tissue specificity for infection. HPV infection can result in a range of benign lesions, for example verrucas on the feet, common warts on the hands, or genital warts. HPV infects dividing basal epithelial cells where its dsDNA episomal genome enters the nuclei. Upon basal cell division, an infected daughter cell begins the process of keratinocyte differentiation that triggers a tightly orchestrated pattern of viral gene expression to accomplish a productive infection. A subset of mucosal-infective HPVs, the so-called ‘high risk’ (HR) HPVs, cause cervical disease, categorized as low or high grade. Most individuals will experience transient HR-HPV infection during their lifetime but these infections will not progress to clinically significant cervical disease or cancer because the immune system eventually recognizes and clears the virus. Cancer progression is due to persistent infection with an HR-HPV. HR-HPV infection is the cause of >99.7% cervical cancers in women, and a subset of oropharyngeal cancers, predominantly in men. HPV16 (HR-HPV genotype 16) is the most prevalent worldwide and the major cause of HPV-associated cancers. At the molecular level, cancer progression is due to increased expression of the viral oncoproteins E6 and E7, which activate the cell cycle, inhibit apoptosis, and allow accumulation of DNA damage. This review aims to describe the productive life cycle of HPV and discuss the roles of the viral proteins in HPV replication. Routes to viral persistence and cancer progression are also discussed.
Collapse
|
20
|
The CXCL12/CXCR4 Signaling Pathway: A New Susceptibility Factor in Human Papillomavirus Pathogenesis. PLoS Pathog 2016; 12:e1006039. [PMID: 27918748 PMCID: PMC5138052 DOI: 10.1371/journal.ppat.1006039] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 11/02/2016] [Indexed: 12/25/2022] Open
Abstract
The productive human papillomavirus (HPV) life cycle is tightly linked to the differentiation and cycling of keratinocytes. Deregulation of these processes and stimulation of cell proliferation by the action of viral oncoproteins and host cell factors underlies HPV-mediated carcinogenesis. Severe HPV infections characterize the wart, hypogammaglobulinemia, infection, and myelokathexis (WHIM) immunodeficiency syndrome, which is caused by gain-of-function mutations in the CXCR4 receptor for the CXCL12 chemokine, one of which is CXCR41013. We investigated whether CXCR41013 interferes in the HPV18 life cycle in epithelial organotypic cultures. Expression of CXCR41013 promoted stabilization of HPV oncoproteins, thus disturbing cell cycle progression and proliferation at the expense of the ordered expression of the viral genes required for virus production. Conversely, blocking CXCR41013 function restored virus production and limited HPV-induced carcinogenesis. Thus, CXCR4 and its potential activation by genetic alterations in the course of the carcinogenic process can be considered as an important host factor for HPV carcinogenesis. Human papillomaviruses (HPV) are epitheliotropic tumor viruses causing mostly benign warts but that have developed strategies to establish persistent infections. Although host immune responses clear most infections, persistence of some HPV types causes ~5% of human cancers and severe pathogenesis in immunosuppressed individuals. How early events in HPV infection, determined by the interaction between viral and host proteins, might lead to viral persistence and pathogenesis is unknown. Here, we thought to investigate this issue by providing mechanistic insights into the selective susceptibility to HPV pathogenesis displayed by patients who are immunosuppressed as a consequence of mutations in the CXCR4 gene encoding for the receptor of the CXCL12 chemokine (WHIM syndrome). We previously unraveled the existence of a general interplay between the CXCL12/CXCR4 axis and HPV, which is hijacked toward cell transformation upon expression of the CXCR4 mutant. Here, using three dimensional epithelial cell cultures to analyze the HPV life cycle, we found that the CXCR4 mutant promotes cell hyperproliferation and stabilization of viral oncoprotein expression at the expense of virus production. Our results, which identify CXCR4 as an important gatekeeper of keratinocyte proliferation and as a new susceptibility factor in HPV pathogenesis, may be translated into anti-viral and anti-cancer strategies.
Collapse
|
21
|
Stuqui B, Conceição ALG, Termini L, Sichero L, Villa LL, Rahal P, Calmon MDF. The differential role of HTRA1 in HPV-positive and HPV-negative cervical cell line proliferation. BMC Cancer 2016; 16:840. [PMID: 27809811 PMCID: PMC5095955 DOI: 10.1186/s12885-016-2873-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 10/21/2016] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND High-risk human papillomaviruses (HPVs) are strongly associated with the development of some malignancies. The E6 and E7 viral oncoproteins are the primary proteins responsible for cell homeostasis alteration and immortalization. Furthermore, the E6 protein from high-risk HPVs can interact with the PDZ (PSD-90/Dlg/ZO-1) domains of cellular proteins, triggering cell transformation. One protein that is associated with pathological conditions and has a PDZ domain is the protease HTRA1 (high temperature requirement 1). This protein is poorly expressed in some cancers, suggesting a tumor suppressor role. The aim of this study was to evaluate the effect of HTRA1 overexpression in HPV16-positive (CasKi) and HPV-negative (C33) cervical cell lines. METHODS The cells were transfected with a vector containing the HTRA1 ORF or an empty vector. HTRA1 overexpression was confirmed by qRT-PCR. The cells were subjected to cell proliferation, colony formation, apoptosis and cell cycle assays. RESULTS C33 cells expressing HTRA1 grew significantly fewer colonies and showed less proliferation than cells without HTRA1 expression. In contrast, in the CasKi cells overexpressing HTRA1, there was an increase in the cell growth rate and in the colonies density compared to cells expressing low levels of HTRA1. An apoptosis assay showed that HTRA1 does not interfere with the apoptosis rate in these cells. A cell cycle immunofluorescence assay revealed more CasKi cells overexpressing HTRA1 in the S phase and more C33 HTRA1-transfected cells in the G0/G1 phase, suggesting that HTRA1 plays different roles in the cell cycle progression of these cells. CONCLUSIONS HTRA1 overexpression prevents cell proliferation in the HPV-negative cell line and increases cell proliferation in the HPV-positive cell line. Although the E6/HTRA1 interaction has already been described in the literature, more studies are required to confirm whether the present functional findings are a result of this interaction.
Collapse
Affiliation(s)
- Bruna Stuqui
- Department of Biology, Instituto de Biociências, Letras e Ciências Exatas - IBILCE/UNESP, Rua Cristóvão Colombo n° 2265, Jardim Nazareth, CEP 15054-000 São José do Rio Preto, SP Brazil
| | - André Luis Giacometti Conceição
- Department of Biology, Instituto de Biociências, Letras e Ciências Exatas - IBILCE/UNESP, Rua Cristóvão Colombo n° 2265, Jardim Nazareth, CEP 15054-000 São José do Rio Preto, SP Brazil
| | - Lara Termini
- Center for Translational Investigation in Oncology, Instituto do Câncer do Estado de São Paulo, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Av. Dr. Arnaldo, 251, 8° andar, Bairro Cerqueira César, CEP 01246-000 São Paulo Brazil
| | - Laura Sichero
- Center for Translational Investigation in Oncology, Instituto do Câncer do Estado de São Paulo, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Av. Dr. Arnaldo, 251, 8° andar, Bairro Cerqueira César, CEP 01246-000 São Paulo Brazil
| | - Luisa Lina Villa
- Center for Translational Investigation in Oncology, Instituto do Câncer do Estado de São Paulo, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Av. Dr. Arnaldo, 251, 8° andar, Bairro Cerqueira César, CEP 01246-000 São Paulo Brazil
- Department of Radiology and Oncology, Faculdade de Medicina, Universidade de São Paulo, Av. Dr. Arnaldo, 251, 8° andar, Bairro Cerqueira César, CEP 01246-000 São Paulo Brazil
| | - Paula Rahal
- Department of Biology, Instituto de Biociências, Letras e Ciências Exatas - IBILCE/UNESP, Rua Cristóvão Colombo n° 2265, Jardim Nazareth, CEP 15054-000 São José do Rio Preto, SP Brazil
| | - Marília de Freitas Calmon
- Department of Biology, Instituto de Biociências, Letras e Ciências Exatas - IBILCE/UNESP, Rua Cristóvão Colombo n° 2265, Jardim Nazareth, CEP 15054-000 São José do Rio Preto, SP Brazil
| |
Collapse
|
22
|
Ganti K, Massimi P, Manzo-Merino J, Tomaić V, Pim D, Playford MP, Lizano M, Roberts S, Kranjec C, Doorbar J, Banks L. Interaction of the Human Papillomavirus E6 Oncoprotein with Sorting Nexin 27 Modulates Endocytic Cargo Transport Pathways. PLoS Pathog 2016; 12:e1005854. [PMID: 27649450 PMCID: PMC5029876 DOI: 10.1371/journal.ppat.1005854] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 08/09/2016] [Indexed: 01/05/2023] Open
Abstract
A subset of high-risk Human Papillomaviruses (HPVs) are the causative agents of a large number of human cancers, of which cervical is the most common. Two viral oncoproteins, E6 and E7, contribute directly towards the development and maintenance of malignancy. A characteristic feature of the E6 oncoproteins from cancer-causing HPV types is the presence of a PDZ binding motif (PBM) at its C-terminus, which confers interaction with cellular proteins harbouring PDZ domains. Here we show that this motif allows E6 interaction with Sorting Nexin 27 (SNX27), an essential component of endosomal recycling pathways. This interaction is highly conserved across E6 proteins from multiple high-risk HPV types and is mediated by a classical PBM-PDZ interaction but unlike many E6 targets, SNX27 is not targeted for degradation by E6. Rather, in HPV-18 positive cell lines the association of SNX27 with components of the retromer complex and the endocytic transport machinery is altered in an E6 PBM-dependent manner. Analysis of a SNX27 cargo, the glucose transporter GLUT1, reveals an E6-dependent maintenance of GLUT1 expression and alteration in its association with components of the endocytic transport machinery. Furthermore, knockdown of E6 in HPV-18 positive cervical cancer cells phenocopies the loss of SNX27, both in terms of GLUT1 expression levels and its vesicular localization, with a concomitant marked reduction in glucose uptake, whilst loss of SNX27 results in slower cell proliferation in low nutrient conditions. These results demonstrate that E6 interaction with SNX27 can alter the recycling of cargo molecules, one consequence of which is modulation of nutrient availability in HPV transformed tumour cells.
Collapse
Affiliation(s)
- Ketaki Ganti
- International Centre for Genetic Engineering and Biotechnology, Padriciano, Trieste, Italy
| | - Paola Massimi
- International Centre for Genetic Engineering and Biotechnology, Padriciano, Trieste, Italy
| | - Joaquin Manzo-Merino
- CONACyT Research Fellow, Instituto Nacional de Cancerologia, Mexico/Instituto de Investigaciones Biomedicas, Universidad Nacional Autonoma de Mexico. Col. Seccion XVI, Tlalpan, Mexico
| | - Vjekoslav Tomaić
- International Centre for Genetic Engineering and Biotechnology, Padriciano, Trieste, Italy
- Division of Molecular Medicine, Ruđjer Bošković Institute, Zagreb, Croatia
| | - David Pim
- International Centre for Genetic Engineering and Biotechnology, Padriciano, Trieste, Italy
| | - Martin P. Playford
- National Heart, Blood and Lung Institute, NIH, Bethesda, Maryland, United States of America
| | - Marcela Lizano
- Instituto Nacional de Cancerologia, Mexico/Instituto de Investigaciones Biomedicas, Universidad Nacional Autonoma de Mexico. Col. Seccion XVI, Tlalpan, Mexico
| | - Sally Roberts
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Christian Kranjec
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, United Kingdom
| | - John Doorbar
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, United Kingdom
| | - Lawrence Banks
- International Centre for Genetic Engineering and Biotechnology, Padriciano, Trieste, Italy
- * E-mail:
| |
Collapse
|
23
|
Thomas M, Myers MP, Massimi P, Guarnaccia C, Banks L. Analysis of Multiple HPV E6 PDZ Interactions Defines Type-Specific PDZ Fingerprints That Predict Oncogenic Potential. PLoS Pathog 2016; 12:e1005766. [PMID: 27483446 PMCID: PMC4970744 DOI: 10.1371/journal.ppat.1005766] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 06/23/2016] [Indexed: 11/30/2022] Open
Abstract
The high-risk Human Papillomavirus (HPV) E6 oncoproteins are characterised by the presence of a class I PDZ-binding motif (PBM) on their extreme carboxy termini. The PBM is present on the E6 proteins derived from all cancer-causing HPV types, but can also be found on some related non-cancer-causing E6 proteins. We have therefore been interested in investigating the potential functional differences between these different E6 PBMs. Using an unbiased proteomic approach in keratinocytes, we have directly compared the interaction profiles of these different PBMs. This has allowed us to identify the potential PDZ target fingerprints of the E6 PBMs from 7 different cancer-causing HPV types, from 3 HPV types with weak cancer association, and from one benign HPV type that possesses an ancestral PBM. We demonstrate a striking increase in the number of potential PDZ targets bound by each E6 PBM as cancer-causing potential increases, and show that the HPV-16 and HPV-18 PBMs have the most flexibility in their PDZ target selection. Furthermore, the specific interaction with hScrib correlates directly with increased oncogenic potential. In contrast, hDlg is bound equally well by all the HPV E6 PBMs analysed, indicating that this is an evolutionarily conserved interaction, and was most likely one of the original E6 PBM target proteins that was important for the occupation of a potential new niche. Finally, we present evidence that the cell junction components ZO-2 and β-2 syntrophin are novel PDZ domain–containing targets of a subset of high-risk HPV types. The cancer-causing Human Papillomavirus (HPV) E6 oncoproteins have a unique carboxy terminal PDZ binding motif (PBM), which interacts with a number of different cellular PDZ domain-containing substrates. The PBM has important functions in both the viral life cycle and in HPV-induced malignancy. In this study we have used a proteomic approach to compare the ability of multiple HPV E6 oncoproteins to interact with different cellular PDZ proteins. We show a striking increase in the number of PDZ proteins recognised as the oncogenic potential of the individual E6 increases. Furthermore, we define combinations of PDZ proteins that are predictors of oncogenic potential, whilst others represent evolutionarily conserved targets bound across the evolutionary spectrum of low and high-risk PBM-containing E6 proteins. Taken together, these studies shed light on the functional conservation in the E6 PBM across multiple HPV types and support the hypothesis that ancestral PBM evolution originally conferred association with a restricted number of PDZ targets, which has, over time, evolved, to provide increased levels of flexibility and hence increase the number of cellular PDZ partners that can be bound by the cancer-causing E6 oncoproteins.
Collapse
Affiliation(s)
- Miranda Thomas
- Tumour Virology, International Centre for Genetic Engineering and Biotechnology (I.C.G.E.B.), Trieste, Italy
- * E-mail: (MT); (LB)
| | - Michael P. Myers
- Protein Networks, International Centre for Genetic Engineering and Biotechnology (I.C.G.E.B.), Trieste, Italy
| | - Paola Massimi
- Tumour Virology, International Centre for Genetic Engineering and Biotechnology (I.C.G.E.B.), Trieste, Italy
| | - Corrado Guarnaccia
- Biotechnology Development, International Centre for Genetic Engineering and Biotechnology (I.C.G.E.B.), Trieste, Italy
| | - Lawrence Banks
- Tumour Virology, International Centre for Genetic Engineering and Biotechnology (I.C.G.E.B.), Trieste, Italy
- * E-mail: (MT); (LB)
| |
Collapse
|
24
|
The high-risk HPV E6 target scribble (hScrib) is required for HPV E6 expression in cervical tumour-derived cell lines. PAPILLOMAVIRUS RESEARCH 2016; 2:70-77. [PMID: 29074188 PMCID: PMC5886876 DOI: 10.1016/j.pvr.2016.04.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 03/08/2016] [Accepted: 04/05/2016] [Indexed: 11/21/2022]
Abstract
The ability of high-risk HPV E6 oncoproteins to target cellular proteins which harbor PDZ domains is believed to play an important role in the virus life cycle and to influence the ability of these viruses to bring about malignant transformation. Whilst many of these PDZ proteins are potential tumour suppressors, involved in the control of cell polarity and cell-contact, recent studies suggest that mislocalisation or overexpression might result in the emergence of oncogenic functions. This has been shown most clearly for two E6 targets, hDlg and hScrib. In this study we show that hScrib plays such a role in HeLa cells, where its expression is required for maintaining high levels of HPV-18 E6 protein. Loss of hScrib has no effect on E6 stability but results in lower levels of E6 transcription and a reduced rate of E6 translation. We further show that, in the context of cervical tumour-derived cell lines, both hScrib and E6 cooperate in the activation of the S6 kinase signaling pathway, and thereby contribute towards maintaining high rates of protein translation. These results indicate that the residual hScrib that is present within HPV transformed cells is pro-oncogenic, and highlights the dual functions of E6 cell polarity targets.
Collapse
|
25
|
James CD, Roberts S. Viral Interactions with PDZ Domain-Containing Proteins-An Oncogenic Trait? Pathogens 2016; 5:pathogens5010008. [PMID: 26797638 PMCID: PMC4810129 DOI: 10.3390/pathogens5010008] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 01/14/2016] [Accepted: 01/15/2016] [Indexed: 02/06/2023] Open
Abstract
Many of the human viruses with oncogenic capabilities, either in their natural host or in experimental systems (hepatitis B and C, human T cell leukaemia virus type 1, Kaposi sarcoma herpesvirus, human immunodeficiency virus, high-risk human papillomaviruses and adenovirus type 9), encode in their limited genome the ability to target cellular proteins containing PSD95/ DLG/ZO-1 (PDZ) interaction modules. In many cases (but not always), the viruses have evolved to bind the PDZ domains using the same short linear peptide motifs found in host protein-PDZ interactions, and in some cases regulate the interactions in a similar fashion by phosphorylation. What is striking is that the diverse viruses target a common subset of PDZ proteins that are intimately involved in controlling cell polarity and the structure and function of intercellular junctions, including tight junctions. Cell polarity is fundamental to the control of cell proliferation and cell survival and disruption of polarity and the signal transduction pathways involved is a key event in tumourigenesis. This review focuses on the oncogenic viruses and the role of targeting PDZ proteins in the virus life cycle and the contribution of virus-PDZ protein interactions to virus-mediated oncogenesis. We highlight how many of the viral associations with PDZ proteins lead to deregulation of PI3K/AKT signalling, benefitting virus replication but as a consequence also contributing to oncogenesis.
Collapse
Affiliation(s)
- Claire D James
- Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Vincent Drive, Birmingham B15 2TT, UK.
- Present address; Virginia Commonwealth University, School of Dentistry, W. Baxter Perkinson Jr. Building, 521 North 11th Street, P.O. Box 980566, Richmond, VA 23298-0566, USA.
| | - Sally Roberts
- Institute of Cancer and Genomic Sciences, College of Medical and Dental Sciences, University of Birmingham, Vincent Drive, Birmingham B15 2TT, UK.
| |
Collapse
|
26
|
Doorbar J, Egawa N, Griffin H, Kranjec C, Murakami I. Human papillomavirus molecular biology and disease association. Rev Med Virol 2015; 25 Suppl 1:2-23. [PMID: 25752814 PMCID: PMC5024016 DOI: 10.1002/rmv.1822] [Citation(s) in RCA: 524] [Impact Index Per Article: 58.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Revised: 06/12/2014] [Accepted: 06/25/2014] [Indexed: 12/27/2022]
Abstract
Human papillomaviruses (HPVs) have evolved over millions of years to propagate themselves in a range of different animal species including humans. Viruses that have co‐evolved slowly in this way typically cause chronic inapparent infections, with virion production in the absence of apparent disease. This is the case for many Beta and Gamma HPV types. The Alpha papillomavirus types have however evolved immunoevasion strategies that allow them to cause persistent visible papillomas. These viruses activate the cell cycle as the infected epithelial cell differentiates in order to create a replication competent environment that allows viral genome amplification and packaging into infectious particles. This is mediated by the viral E6, E7, and E5 proteins. High‐risk E6 and E7 proteins differ from their low‐risk counterparts however in being able to drive cell cycle entry in the upper epithelial layers and also to stimulate cell proliferation in the basal and parabasal layers. Deregulated expression of these cell cycle regulators underlies neoplasia and the eventual progression to cancer in individuals who cannot resolve high‐risk HPV infection. Most work to date has focused on the study of high‐risk HPV types such as HPV 16 and 18, which has led to an understanding of the molecular pathways subverted by these viruses. Such approaches will lead to the development of better strategies for disease treatment, including targeted antivirals and immunotherapeutics. Priorities are now focused toward understanding HPV neoplasias at sites other than the cervix (e.g. tonsils, other transformation zones) and toward understanding the mechanisms by which low‐risk HPV types can sometimes give rise to papillomatosis and under certain situations even cancers. Copyright © 2015 John Wiley & Sons, Ltd.
Collapse
Affiliation(s)
- John Doorbar
- Department of Pathology, University of Cambridge, Cambridge, UK
| | | | | | | | | |
Collapse
|
27
|
Sun P, Dong L, MacDonald AI, Akbari S, Edward M, Hodgins MB, Johnstone SR, Graham SV. HPV16 E6 Controls the Gap Junction Protein Cx43 in Cervical Tumour Cells. Viruses 2015; 7:5243-56. [PMID: 26445057 PMCID: PMC4632379 DOI: 10.3390/v7102871] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 09/24/2015] [Accepted: 09/30/2015] [Indexed: 12/16/2022] Open
Abstract
Human papillomavirus type 16 (HPV16) causes a range of cancers including cervical and head and neck cancers. HPV E6 oncoprotein binds the cell polarity regulator hDlg (human homologue of Drosophila Discs Large). Previously we showed in vitro, and now in vivo, that hDlg also binds Connexin 43 (Cx43), a major component of gap junctions that mediate intercellular transfer of small molecules. In HPV16-positive non-tumour cervical epithelial cells (W12G) Cx43 localised to the plasma membrane, while in W12T tumour cells derived from these, it relocated with hDlg into the cytoplasm. We now provide evidence that E6 regulates this cytoplasmic pool of Cx43. E6 siRNA depletion in W12T cells resulted in restoration of Cx43 and hDlg trafficking to the cell membrane. In C33a HPV-negative cervical tumour cells expressing HPV16 or 18 E6, Cx43 was located primarily in the cytoplasm, but mutation of the 18E6 C-terminal hDlg binding motif resulted in redistribution of Cx43 to the membrane. The data indicate for the first time that increased cytoplasmic E6 levels associated with malignant progression alter Cx43 trafficking and recycling to the membrane and the E6/hDlg interaction may be involved. This suggests a novel E6-associated mechanism for changes in Cx43 trafficking in cervical tumour cells.
Collapse
Affiliation(s)
- Peng Sun
- Feinberg School of Medicine, North Western University, Chicago, IL 60611, USA.
| | - Li Dong
- MRC-University of Glasgow Centre for Virus Research, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Garscube Estate, Glasgow G61 1QH, Scotland, UK.
| | - Alasdair I MacDonald
- MRC-University of Glasgow Centre for Virus Research, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Garscube Estate, Glasgow G61 1QH, Scotland, UK.
| | - Shahrzad Akbari
- MRC-University of Glasgow Centre for Virus Research, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Garscube Estate, Glasgow G61 1QH, Scotland, UK.
| | - Michael Edward
- Dermatology, School of Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8TT, Scotland, UK.
| | - Malcolm B Hodgins
- Dermatology, School of Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8TT, Scotland, UK.
| | - Scott R Johnstone
- Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8TT, Scotland, UK.
| | - Sheila V Graham
- MRC-University of Glasgow Centre for Virus Research, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Garscube Estate, Glasgow G61 1QH, Scotland, UK.
| |
Collapse
|
28
|
Ganti K, Broniarczyk J, Manoubi W, Massimi P, Mittal S, Pim D, Szalmas A, Thatte J, Thomas M, Tomaić V, Banks L. The Human Papillomavirus E6 PDZ Binding Motif: From Life Cycle to Malignancy. Viruses 2015; 7:3530-51. [PMID: 26147797 PMCID: PMC4517114 DOI: 10.3390/v7072785] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Revised: 06/24/2015] [Accepted: 06/25/2015] [Indexed: 01/01/2023] Open
Abstract
Cancer-causing HPV E6 oncoproteins are characterized by the presence of a PDZ binding motif (PBM) at their extreme carboxy terminus. It was long thought that this region of E6 had a sole function to confer interaction with a defined set of cellular substrates. However, more recent studies have shown that the E6 PBM has a complex pattern of regulation, whereby phosphorylation within the PBM can regulate interaction with two classes of cellular proteins: those containing PDZ domains and the members of the 14-3-3 family of proteins. In this review, we explore the roles that the PBM and its ligands play in the virus life cycle, and subsequently how these can inadvertently contribute towards the development of malignancy. We also explore how subtle alterations in cellular signal transduction pathways might result in aberrant E6 phosphorylation, which in turn might contribute towards disease progression.
Collapse
Affiliation(s)
- Ketaki Ganti
- International Center for Genetic Engineering and Biotechnology, Area Science Park, Padriciano 99, Trieste 34149, Italy.
| | - Justyna Broniarczyk
- International Center for Genetic Engineering and Biotechnology, Area Science Park, Padriciano 99, Trieste 34149, Italy.
| | - Wiem Manoubi
- International Center for Genetic Engineering and Biotechnology, Area Science Park, Padriciano 99, Trieste 34149, Italy.
| | - Paola Massimi
- International Center for Genetic Engineering and Biotechnology, Area Science Park, Padriciano 99, Trieste 34149, Italy.
| | - Suruchi Mittal
- International Center for Genetic Engineering and Biotechnology, Area Science Park, Padriciano 99, Trieste 34149, Italy.
| | - David Pim
- International Center for Genetic Engineering and Biotechnology, Area Science Park, Padriciano 99, Trieste 34149, Italy.
| | - Anita Szalmas
- International Center for Genetic Engineering and Biotechnology, Area Science Park, Padriciano 99, Trieste 34149, Italy.
| | - Jayashree Thatte
- International Center for Genetic Engineering and Biotechnology, Area Science Park, Padriciano 99, Trieste 34149, Italy.
| | - Miranda Thomas
- International Center for Genetic Engineering and Biotechnology, Area Science Park, Padriciano 99, Trieste 34149, Italy.
| | - Vjekoslav Tomaić
- International Center for Genetic Engineering and Biotechnology, Area Science Park, Padriciano 99, Trieste 34149, Italy.
| | - Lawrence Banks
- International Center for Genetic Engineering and Biotechnology, Area Science Park, Padriciano 99, Trieste 34149, Italy.
| |
Collapse
|
29
|
Cotugno R, Basile A, Romano E, Gallotta D, Belisario MA. BAG3 down-modulation sensitizes HPV18(+) HeLa cells to PEITC-induced apoptosis and restores p53. Cancer Lett 2014; 354:263-71. [PMID: 25175321 PMCID: PMC7116956 DOI: 10.1016/j.canlet.2014.08.022] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Revised: 07/28/2014] [Accepted: 08/18/2014] [Indexed: 12/19/2022]
Abstract
BAG3 is a multi-functional component of tumor cell pro-survival machinery, and its biological functions have been largely associated to proteasome system. Here, we show that BAG3 down-modulation resulted in reduced cell viability and enhanced PEITC-induced apoptosis largely more extensively in HeLa (HPV18(+)) rather than in C33A (HPV(-)) cervical carcinoma cell lines. Moreover, we demonstrate that BAG3 suppression led to a decrease of viral E6 oncoprotein and a concomitant recovery of p53 tumor suppressor, the best recognized target of E6 for proteasome degradation. E6 and p53 expression were modulated at protein level, since their respective mRNAs were unaffected. Taken together our findings reveal a novel role for BAG3 as host protein contributing to HPV18 E6-activated pro-survival strategies, and suggest a possible relevance of its expression levels in drug/radiotherapy-resistance of HPV18-bearing cervical carcinomas.
Collapse
Affiliation(s)
- Roberta Cotugno
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II n.132, Fisciano, 84084, Salerno, Italy
| | - Anna Basile
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II n.132, Fisciano, 84084, Salerno, Italy
| | - Elena Romano
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II n.132, Fisciano, 84084, Salerno, Italy
| | - Dario Gallotta
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II n.132, Fisciano, 84084, Salerno, Italy
| | - Maria Antonietta Belisario
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II n.132, Fisciano, 84084, Salerno, Italy.
| |
Collapse
|
30
|
Cancer-causing human papillomavirus E6 proteins display major differences in the phospho-regulation of their PDZ interactions. J Virol 2014; 89:1579-86. [PMID: 25410862 DOI: 10.1128/jvi.01961-14] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
UNLABELLED Previous studies have shown that the cancer-causing high-risk human papillomavirus (HPV) E6 oncoproteins have PDZ binding potential, an activity which is important for their ability to support the viral life cycle and to cooperate in the induction of malignancy. However, PDZ interactions are not constitutive, and they can be negatively regulated by phosphorylation within the E6 PDZ binding motif (PBM). In this study, we have investigated the differential regulation of the HPV E6 PBMs from diverse high-risk HPV types. We show that, depending on the HPV type, PDZ binding activity can be regulated by phosphorylation with protein kinase A (PKA) or AKT, which, in turn, inhibits PDZ recognition. Such regulation is highly conserved between E6 proteins derived from HPV-16, HPV-18, and HPV-58 while being somewhat weaker or absent from other types such as HPV-31, HPV-33, and HPV-51. In the case of HPV31, PKA phosphorylation occurs within the core of the E6 protein and has no effect on PDZ interactions, and this demonstrates a surprising degree of heterogeneity among the different high-risk HPV E6 oncoproteins in how they are regulated by different cellular signaling pathways. IMPORTANCE This study demonstrated that the cancer-causing HPV E6 oncoproteins are all subject to posttranslational modification of their extreme C-terminal PDZ binding motifs through phosphorylation. However, the identities of the kinase are not the same for all HPV types. This demonstrates a very important divergence between these HPVs, and it suggests that changes in cell signaling pathways have different consequences for different high-risk virus infections and their associated malignancies.
Collapse
|
31
|
PDZRN3/LNX3 is a novel target of human papillomavirus type 16 (HPV-16) and HPV-18 E6. J Virol 2014; 89:1439-44. [PMID: 25355882 DOI: 10.1128/jvi.01743-14] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
High-risk human papillomavirus (HPV) E6 proteins have a C-terminal PDZ binding motif through which they bind, and target for proteasome-mediated degradation, a number of PDZ-containing cellular targets. Recent studies have suggested that the RING-containing ubiquitin-protein ligase PDZRN3 might also be an HPV E6 target. In this analysis, we show that HPV-16 and HPV-18 E6 can target PDZRN3 in a PDZ- and proteasome-dependent manner and provide a connection between the HPV life cycle and differentiation-related STAT signaling.
Collapse
|
32
|
The role of ubiquitin and ubiquitin-like modification systems in papillomavirus biology. Viruses 2014; 6:3584-611. [PMID: 25254385 PMCID: PMC4189040 DOI: 10.3390/v6093584] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Revised: 09/17/2014] [Accepted: 09/18/2014] [Indexed: 12/12/2022] Open
Abstract
Human papillomaviruses (HPVs) are small DNA viruses that are important etiological agents of a spectrum of human skin lesions from benign to malignant. Because of their limited genome coding capacity they express only a small number of proteins, only one of which has enzymatic activity. Additionally, the HPV productive life cycle is intimately tied to the epithelial differentiation program and they must replicate in what are normally non-replicative cells, thus, these viruses must reprogram the cellular environment to achieve viral reproduction. Because of these limitations and needs, the viral proteins have evolved to co-opt cellular processes primarily through protein-protein interactions with critical host proteins. The ubiquitin post-translational modification system and the related ubiquitin-like modifiers constitute a widespread cellular regulatory network that controls the levels and functions of thousands of proteins, making these systems an attractive target for viral manipulation. This review describes the interactions between HPVs and the ubiquitin family of modifiers, both to regulate the viral proteins themselves and to remodel the host cell to facilitate viral survival and reproduction.
Collapse
|
33
|
Abstract
Fifty years ago, inoculation with bovine papillomavirus (BPV) was found to cause mesenchymal tumors of the skin in cattle and horses, as well as tumors of the bladder in cattle. Subsequent to these studies of BPVs, human papillomaviruses (HPVs) were found to cause cervical cancer resulting in intense research into papillomaviruses. During the past 50 years, the ways that HPVs and BPVs cause disease have been investigated, and both HPVs and BPVs have been associated with an increasingly diverse range of diseases. Herein, the biology, oncogenic mechanisms, and diseases associated with BPVs are compared with those of HPVs. As reviewed, there are currently significant differences between BPVs and HPVs. However, research 50 years ago into BPVs formed a prologue for the recognition that papillomaviruses have a significant role in human disease, and it is possible that future research may similarly reveal that BPVs are less different from HPVs than is currently recognized.
Collapse
Affiliation(s)
- J. S. Munday
- Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand
| |
Collapse
|
34
|
Papillomavirus E6 PDZ interactions can be replaced by repression of p53 to promote episomal human papillomavirus genome maintenance. J Virol 2013; 88:3027-30. [PMID: 24352452 DOI: 10.1128/jvi.02360-13] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Cancer-associated human papillomaviruses (HPVs) express E6 oncoproteins that target the degradation of p53 and have a carboxy-terminal PDZ ligand that is required for stable episomal maintenance of the HPV genome. We find that the E6 PDZ ligand can be deleted and the HPV genome stably maintained if cellular p53 is inactivated. This indicates that the E6-PDZ interaction promotes HPV genome maintenance at least in part by neutralization of an activity that can arise from residual undegraded p53.
Collapse
|
35
|
Lorenz LD, Rivera Cardona J, Lambert PF. Inactivation of p53 rescues the maintenance of high risk HPV DNA genomes deficient in expression of E6. PLoS Pathog 2013; 9:e1003717. [PMID: 24204267 PMCID: PMC3812038 DOI: 10.1371/journal.ppat.1003717] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Accepted: 09/03/2013] [Indexed: 01/28/2023] Open
Abstract
The human papillomavirus DNA genome undergoes three distinct stages of replication: establishment, maintenance and amplification. We show that the HPV16 E6 protein is required for the maintenance of the HPV16 DNA genome as an extrachromosomal, nuclear plasmid in its natural host cell, the human keratinocyte. Based upon mutational analyses, inactivation of p53 by E6, but not necessarily E6-mediated degradation of p53, was found to correlate with the ability of E6 to support maintenance of the HPV16 genome as a nuclear plasmid. Inactivation of p53 with dominant negative p53 rescued the ability of HPV16 E6STOP and E6SAT mutant genomes to replicate as extrachromosomal genomes, though not to the same degree as observed for the HPV16 E6 wild-type (WT) genome. Inactivation of p53 also rescued the ability of HPV18 and HPV31 E6-deficient genomes to be maintained at copy numbers comparable to that of HPV18 and HPV31 E6WT genomes at early passages, though upon further passaging copy numbers for the HPV18 and 31 E6-deficient genomes lessened compared to that of the WT genomes. We conclude that inactivation of p53 is necessary for maintenance of HPV16 and for HPV18 and 31 to replicate at WT copy number, but that additional functions of E6 independent of inactivating p53 must also contribute to the maintenance of these genomes. Together these results suggest that re-activation of p53 may be a possible means for eradicating extrachromosomal HPV16, 18 or 31 genomes in the context of persistent infections. Human papillomaviruses (HPVs) infect epithelial tissues. HPVs that infect mucosal epithelia cause infectious lesions in the anogenital tract and oral cavity. HPV infections are normally cleared by the immune system; however, in rare cases, infections can persist for years. Persistent infections by certain HPVs place one at a high risk of developing carcinomas of the cervix, other anogenital tissues, and the head/neck region. These HPVs are responsible for over 5% of all human cancers. For an HPV infection to persist, the viral circular genome must be maintained, i.e. replicated and inherited during cell division. In this study we define the mechanism by which the viral gene E6 contributes to the maintenance of the HPV genome. We demonstrate that E6 must inactivate the cellular factor, p53, for the viral genome to be maintained. Significantly, p53, is inactivated in many types of human cancers and because much research has been done on p53, promising new drugs have been identified that can re-activate p53. If such drugs can re-activate the p53 that has been inactivated by E6, then we hypothesize that these drugs could be used to cure patients with persistent HPV infections and thereby reduce their risk of developing HPV associated cancers.
Collapse
Affiliation(s)
- Laurel D. Lorenz
- McArdle Laboratory for Cancer Research, University of Wisconsin Madison School of Medicine and Public Health, Madison, Wisconsin, United States of America
| | - Jessenia Rivera Cardona
- McArdle Laboratory for Cancer Research, University of Wisconsin Madison School of Medicine and Public Health, Madison, Wisconsin, United States of America
| | - Paul F. Lambert
- McArdle Laboratory for Cancer Research, University of Wisconsin Madison School of Medicine and Public Health, Madison, Wisconsin, United States of America
- * E-mail:
| |
Collapse
|
36
|
Manzo-Merino J, Thomas M, Fuentes-Gonzalez AM, Lizano M, Banks L. HPV E6 oncoprotein as a potential therapeutic target in HPV related cancers. Expert Opin Ther Targets 2013; 17:1357-68. [DOI: 10.1517/14728222.2013.832204] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
|
37
|
Stabilization of the angiotensin-(1-7) receptor Mas through interaction with PSD95. Biochem J 2013; 453:345-56. [PMID: 23701246 DOI: 10.1042/bj20121885] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The functions and signalling mechanisms of the Ang-(1-7) [angiotensin-(1-7)] receptor Mas have been studied extensively. However, less attention has been paid to the intracellular regulation of Mas protein. In the present study, PSD95 (postsynaptic density 95), a novel binding protein of Mas receptor, was identified, and their association was characterized further. Mas specifically interacts with PDZ1-2, but not the PDZ3, domain of PSD95 via Mas-CT (Mas C-terminus), and the last four amino acids [ETVV (Glu-Thr-Val-Val)] of Mas-CT were determined to be essential for this interaction, as shown by GST pull-down, co-immunoprecipitation and confocal co-localization experiments. Gain-of-function and loss-of-function studies indicated that PSD95 enhanced Mas protein expression by increasing the stabilization of the receptor. Mas degradation was robustly inhibited by the proteasome inhibitor MG132 in time- and dose-dependent manners, and the expression of PSD95 impaired Mas ubiquitination, indicating that the PSD95-Mas association inhibits Mas receptor degradation via the ubiquitin-proteasome proteolytic pathway. These findings reveal a novel mechanism of Mas receptor regulation by which its expression is modulated at the post-translational level by ubiquitination, and clarify the role of PSD95, which binds directly to Mas, blocking the ubiquitination and subsequent degradation of the receptor via the ubiquitin-proteasome proteolytic pathway.
Collapse
|
38
|
PDZ domains and viral infection: versatile potentials of HPV-PDZ interactions in relation to malignancy. BIOMED RESEARCH INTERNATIONAL 2013; 2013:369712. [PMID: 24093094 PMCID: PMC3777178 DOI: 10.1155/2013/369712] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 07/09/2013] [Accepted: 07/31/2013] [Indexed: 12/13/2022]
Abstract
Cervical cancer is caused by high-risk human papillomaviruses (HPVs), and a unique characteristic of these is a PDZ (P¯SD-95/D¯lg/Z¯O-1-)binding motif in their E6 proteins. Through this motif HPV E6 interacts with a variety of PDZ domain-containing proteins and targets them mainly for degradation. These E6-PDZ interactions exhibit extraordinarily different functions in relation to HPV-induced malignancy, depending upon various cellular contexts; for example, Dlg and Scrib show different distribution patterns from what is seen in normal epithelium, both in localization and in amount, and their loss may be a late-stage marker in malignant progression. Recent studies show that interactions with specific forms of the proteins may have oncogenic potential. In addition, it is interesting that PDZ proteins make a contribution to the stabilization of E6 and viral episomal maintenance during the course of HPV life cycle. Various posttranslational modifications also greatly affect their functions. Phosphorylation of hDlg and hScrib by certain kinases regulates several important signaling cascades, and E6-PDZ interactions themselves are regulated through PKA-dependent phosphorylation. Thus these interactions naturally have great potential for both predictive and therapeutic applications, and, with development of screening tools for identifying novel targets of their interactions, comprehensive spatiotemporal analysis is currently underway.
Collapse
|
39
|
Nussinov R, Ma B, Tsai CJ, Csermely P. Allosteric conformational barcodes direct signaling in the cell. Structure 2013; 21:1509-21. [PMID: 24010710 PMCID: PMC6361540 DOI: 10.1016/j.str.2013.06.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 05/23/2013] [Accepted: 06/05/2013] [Indexed: 01/01/2023]
Abstract
The cellular network is highly interconnected. Pathways merge and diverge. They proceed through shared proteins and may change directions. How are cellular pathways controlled and their directions decided, coded, and read? These questions become particularly acute when we consider that a small number of pathways, such as signaling pathways that regulate cell fates, cell proliferation, and cell death in development, are extensively exploited. This review focuses on these signaling questions from the structural standpoint and discusses the literature in this light. All co-occurring allosteric events (including posttranslational modifications, pathogen binding, and gain-of-function mutations) collectively tag the protein functional site with a unique barcode. The barcode shape is read by an interacting molecule, which transmits the signal. A conformational barcode provides an intracellular address label, which selectively favors binding to one partner and quenches binding to others, and, in this way, determines the pathway direction, and, eventually, the cell's response and fate.
Collapse
Affiliation(s)
- Ruth Nussinov
- Basic Science Program, SAIC-Frederick, Inc., Cancer and Inflammation Program, National Cancer Institute, Frederick, MD 21702, USA; Sackler Institute of Molecular Medicine, Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel.
| | | | | | | |
Collapse
|
40
|
Segura-Cabrera A, García-Pérez CA, Guo X, Rodríguez-Pérez MA. A viral-human interactome based on structural motif-domain interactions captures the human infectome. PLoS One 2013; 8:e71526. [PMID: 23951184 PMCID: PMC3738538 DOI: 10.1371/journal.pone.0071526] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Accepted: 06/28/2013] [Indexed: 11/23/2022] Open
Abstract
Protein interactions between a pathogen and its host are fundamental in the establishment of the pathogen and underline the infection mechanism. In the present work, we developed a single predictive model for building a host-viral interactome based on the identification of structural descriptors from motif-domain interactions of protein complexes deposited in the Protein Data Bank (PDB). The structural descriptors were used for searching, in a database of protein sequences of human and five clinically important viruses; therefore, viral and human proteins sharing a descriptor were predicted as interacting proteins. The analysis of the host-viral interactome allowed to identify a set of new interactions that further explain molecular mechanism associated with viral infections and showed that it was able to capture human proteins already associated to viral infections (human infectome) and non-infectious diseases (human diseasome). The analysis of human proteins targeted by viral proteins in the context of a human interactome showed that their neighbors are enriched in proteins reported with differential expression under infection and disease conditions. It is expected that the findings of this work will contribute to the development of systems biology for infectious diseases, and help guide the rational identification and prioritization of novel drug targets.
Collapse
Affiliation(s)
- Aldo Segura-Cabrera
- Laboratorio de Bioinformática, Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Reynosa, México.
| | | | | | | |
Collapse
|
41
|
The role of protein kinase A regulation of the E6 PDZ-binding domain during the differentiation-dependent life cycle of human papillomavirus type 18. J Virol 2013; 87:9463-72. [PMID: 23804647 PMCID: PMC3754118 DOI: 10.1128/jvi.01234-13] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Human papillomavirus (HPV) E6 proteins of high-risk alpha types target a select group of PSD95/DLG1/ZO1 (PDZ) domain-containing proteins by using a C-terminal PDZ-binding motif (PBM), an interaction that can be negatively regulated by phosphorylation of the E6 PBM by protein kinase A (PKA). Here, we have mutated the canonical PKA recognition motif that partially overlaps with the E6 PBM in the HPV18 genome (E6153PKA) and compared the effect of this mutation on the HPVl8 life cycle in primary keratinocytes with the wild-type genome and with a second mutant genome that lacks the E6 PBM (E6ΔPDZ). Loss of PKA recognition of E6 was associated with increased growth of the genome-containing cells relative to cells carrying the wild-type genome, and upon stratification, a more hyperplastic phenotype, with an increase in the number of S-phase competent cells in the upper suprabasal layers, while the opposite was seen with the E6ΔPDZ genome. Moreover, the growth of wild-type genome-containing cells was sensitive to changes in PKA activity, and these changes were associated with increased phosphorylation of the E6 PBM. In marked contrast to E6ΔPDZ genomes, the E6153PKA mutation exhibited no deleterious effects on viral genome amplification or expression of late proteins. Our data suggest that the E6 PBM function is differentially regulated by phosphorylation in the HPV18 life cycle. We speculate that perturbation of protein kinase signaling pathways could lead to changes in E6 PBM function, which in turn could have a bearing on tumor promotion and progression.
Collapse
|
42
|
Mischo A, Ohlenschläger O, Hortschansky P, Ramachandran R, Görlach M. Structural insights into a wildtype domain of the oncoprotein E6 and its interaction with a PDZ domain. PLoS One 2013; 8:e62584. [PMID: 23638119 PMCID: PMC3640046 DOI: 10.1371/journal.pone.0062584] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 03/22/2013] [Indexed: 12/17/2022] Open
Abstract
The high-risk human papilloma virus (HPV) oncoproteins E6 and E7 interact with key cellular regulators and are etiological agents for tumorigenesis and tumor maintenance in cervical cancer and other malignant conditions. E6 induces degradation of the tumor suppressor p53, activates telomerase and deregulates cell polarity. Analysis of E6 derived from a number of high risk HPV finally yielded the first structure of a wild-type HPV E6 domain (PDB 2M3L) representing the second zinc-binding domain of HPV 51 E6 (termed 51Z2) determined by NMR spectroscopy. The 51Z2 structure provides clues about HPV-type specific structural differences between E6 proteins. The observed temperature sensitivity of the well-folded wild-type E6 domain implies a significant malleability of the oncoprotein in vivo. Hence, the structural differences between individual E6 and their malleability appear, together with HPV type-specific surface exposed side-chains, to provide the structural basis for the different interaction networks reported for individual E6 proteins. Furthermore, the interaction of 51Z2 with a PDZ domain of hDlg was analyzed. Human Dlg constitutes a prototypic representative of the large family of PDZ proteins regulating cell polarity, which are common targets of high-risk HPV E6. Nine C-terminal residues of 51Z2 interact with the second PDZ domain of hDlg2. Surface plasmon resonance in conjunction with the NMR spectroscopy derived complex structure (PDB 2M3M) indicate that E6 residues N-terminal to the canonical PDZ-BM of E6 significantly contribute to this interaction and increase affinity. The structure of the complex reveals how residues outside of the classical PDZ-BM enhance the affinity of E6 towards PDZ domains. Such mechanism facilitates successful competition of E6 with cellular PDZ-binding proteins and may apply to PDZ-binding proteins of other viruses as well.
Collapse
Affiliation(s)
- André Mischo
- Biomolecular NMR Spectroscopy, Leibniz Institute for Age Research - Fritz Lipmann Institute, Jena, Germany
| | - Oliver Ohlenschläger
- Biomolecular NMR Spectroscopy, Leibniz Institute for Age Research - Fritz Lipmann Institute, Jena, Germany
| | - Peter Hortschansky
- Molecular and Applied Microbiology, Leibniz Institute for Natural Product Research and Infection Biology - Hans-Knöll-Institute, Jena, Germany
| | - Ramadurai Ramachandran
- Biomolecular NMR Spectroscopy, Leibniz Institute for Age Research - Fritz Lipmann Institute, Jena, Germany
| | - Matthias Görlach
- Biomolecular NMR Spectroscopy, Leibniz Institute for Age Research - Fritz Lipmann Institute, Jena, Germany
- * E-mail:
| |
Collapse
|
43
|
Abstract
The role of cell polarity regulators in the development of cancer has long been an enigma. Despite displaying characteristics of tumour suppressors, the core regulators of polarity are rarely mutated in tumours and there are few data from animal models to suggest that they directly contribute to cancer susceptibility, thus questioning their relevance to human carcinogenesis. However, a body of data from human tumour viruses is now providing compelling evidence of a central role for the perturbation of cell polarity in the development of cancer.
Collapse
Affiliation(s)
- Lawrence Banks
- The International Centre for Genetic Engineering and Biotechnology, Padriciano 99, I-34149 Trieste, Italy.
| | | | | |
Collapse
|
44
|
High-risk human papillomavirus E6 oncoproteins interact with 14-3-3ζ in a PDZ binding motif-dependent manner. J Virol 2012; 87:1586-95. [PMID: 23175360 DOI: 10.1128/jvi.02074-12] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cervical 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 phosphorylation in 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.
Collapse
|
45
|
Doorbar J, Quint W, Banks L, Bravo IG, Stoler M, Broker TR, Stanley MA. The biology and life-cycle of human papillomaviruses. Vaccine 2012; 30 Suppl 5:F55-70. [PMID: 23199966 DOI: 10.1016/j.vaccine.2012.06.083] [Citation(s) in RCA: 878] [Impact Index Per Article: 73.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Revised: 06/04/2012] [Accepted: 06/05/2012] [Indexed: 12/20/2022]
Abstract
Human papillomaviruses (HPVs) comprise a diverse group, and have different epithelial tropisms and life-cycle strategies. Many HPVs are classified as low-risk, as they are only very rarely associated with neoplasia or cancer in the general population. These HPVs typically cause inapparent/inconspicuous infections, or benign papillomas, which can persist for months or years, but which are eventually resolved by the host's immune system. Low-risk HPVs are difficult to manage in immunosuppressed people and in individuals with genetic predispositions, and can give rise to papillomatosis, and in rare instances, to cancer. The high-risk HPV types are, by contrast, a cause of several important human cancers, including almost all cases of cervical cancer, a large proportion of other anogenital cancers and a growing number of head and neck tumours. The high-risk HPV types constitute a subset of the genus Alphapapillomavirus that are prevalent in the general population, and in most individuals cause only inconspicuous oral and genital lesions. Cancer progression is associated with persistent high-risk HPV infection and with deregulated viral gene expression, which leads to excessive cell proliferation, deficient DNA repair, and the accumulation of genetic damage in the infected cell. Although their life-cycle organisation is broadly similar to that of the low-risk HPV types, the two groups differ significantly in their capacity to drive cell cycle entry and cell proliferation in the basal/parabasal cell layers. This is thought to be linked, at least in part, to different abilities of the high- and low-risk E6 proteins to modulate the activity of p53 and PDZ-domain proteins, and the differential ability of the E7 proteins to target the several different members of the retinoblastoma protein family. This article forms part of a special supplement entitled "Comprehensive Control of HPV Infections and Related Diseases" Vaccine Volume 30, Supplement 5, 2012.
Collapse
Affiliation(s)
- John Doorbar
- Division of Virology, National Institute for Medical Research, London, United Kingdom.
| | | | | | | | | | | | | |
Collapse
|
46
|
Krishna Subbaiah V, Massimi P, Boon SS, Myers MP, Sharek L, Garcia-Mata R, Banks L. The invasive capacity of HPV transformed cells requires the hDlg-dependent enhancement of SGEF/RhoG activity. PLoS Pathog 2012; 8:e1002543. [PMID: 22383878 PMCID: PMC3285591 DOI: 10.1371/journal.ppat.1002543] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Accepted: 01/06/2012] [Indexed: 11/19/2022] Open
Abstract
A major target of the HPV E6 oncoprotein is the human Discs Large (hDlg) tumour suppressor, although how this interaction contributes to HPV-induced malignancy is still unclear. Using a proteomic approach we show that a strong interacting partner of hDlg is the RhoG-specific guanine nucleotide exchange factor SGEF. The interaction between hDlg1 and SGEF involves both PDZ and SH3 domain recognition, and directly contributes to the regulation of SGEF's cellular localization and activity. Consistent with this, hDlg is a strong enhancer of RhoG activity, which occurs in an SGEF-dependent manner. We also show that HPV-18 E6 can interact indirectly with SGEF in a manner that is dependent upon the presence of hDlg and PDZ binding capacity. In HPV transformed cells, E6 maintains a high level of RhoG activity, and this is dependent upon the presence of hDlg and SGEF, which are found in complex with E6. Furthermore, we show that E6, hDlg and SGEF each directly contributes to the invasive capacity of HPV-16 and HPV-18 transformed tumour cells. These studies demonstrate that hDlg has a distinct oncogenic function in the context of HPV induced malignancy, one of the outcomes of which is increased RhoG activity and increased invasive capacity.
Collapse
Affiliation(s)
| | - Paola Massimi
- International Centre for Genetic Engineering and Biotechnology, Trieste, Italy
| | - Siaw Shi Boon
- International Centre for Genetic Engineering and Biotechnology, Trieste, Italy
| | - Michael P. Myers
- International Centre for Genetic Engineering and Biotechnology, Trieste, Italy
| | - Lisa Sharek
- Department of Cell and Developmental Biology, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Rafael Garcia-Mata
- Department of Cell and Developmental Biology, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Lawrence Banks
- International Centre for Genetic Engineering and Biotechnology, Trieste, Italy
- * E-mail:
| |
Collapse
|