|Genetics, Papillomavirus and Human Cancer|
|HEAD||Dr FAVRE Michel / email@example.com|
|MEMBERS||Dr DEMERET Caroline / Dr JACOB Yves / Dr SNIHURA Valeria / Dr VUILLIER Françoise/ BOULABIAR Manel / NEVEU Grégory / ROLLOY Caroline / CASSONNET Patricia / PONS Christian / DELAIRE Marie-Claire / RIBIERRE Hélène
Human papillomaviruses (HPV) are the causative agents of warts, which may affect 20 % of children, and genital proliferations corresponding to the most common sexually transmitted infection. In addition, certain HPV induced carcinoma of the uterine cervix (HPV 16 and HPV18), the second woman cancer worldwide, and of the skin (HPV5) in patients suffering from epidermodysplasia verruciformis (EV). This genodermatosis results from mutations in either of two adjacent genes (EVER1 and EVER2) that confer predisposition to infection with a specific group of viruses (beta-HPV), including HPV5. The beta-HPV are asymptomatic in the general population. Our aim is to better characterize the functions of EVER1 and EVER2 proteins in normal and infected cells and to analyze the role of viral early proteins (E2, E6 and E7) in the HPV life cycle and in the malignant transformation associated with oncogenic HPV. It can be assumed that EVER genes control the expression of HPV genome in infected cells and/or trigger immune response for eradication of lesions.
EVER protein functions.
We have demonstrated that EVER1 and EVER2 form a complex in the endoplasmic reticulum with the zinc transporter ZnT-1. This complex is involved in the maintenance of cellular zinc homeostasis in keratinocytes and plays a central role in HPV-specific protective mechanisms as a negative regulator of some cellular transcription factors (c-Jun, c-Fos) needed for viral genome expression. However, EVER-deficiency caused by a homozygous mutation in either of EVER genes imposes zinc imbalance in keratinocytes and confers susceptibility to beta-HPV infections. More importantly, deregulation of cellular zinc balance emerges as an important step in the life cycle of not only cutaneous beta-HPV but also genital alpha-HPV. We have demonstrated that E5 protein, which is encoded by alpha- but not beta-HPV, disrupts the function of EVER/ZnT 1 complex, leading to the metabolic changes in keratinocytes strikingly similar as mutation in EVER genes does. Our recent data suggest that beta-HPV are defective viruses expressed during epidermal repair processes and favoring cell proliferation during wound healing. As far as the impact of EVER proteins on the control of immune response is concerned, we currently analyze the NFκB signaling pathway and the cytokine expression in cells obtained from EV patients and healthy relatives.
Role of early proteins in HPV life cycle and cell transformation
Our aim is to identify viral protein activities specifically required to initiate and complete HPV life cycle (latency, replication maturation) and to characterize biological properties of early proteins associated with oncogenic potential. Because interaction maps provide a support to conceptualize the intricate relationships between virus-host proteins and to propose hypotheses about their physiopathology, we have performed pioneering analysis to decipher virus-host interactomes. Using a high-throughput yeast two-hybrid approach (Y2H), we have undertaken a large-scale mapping and comparative analysis of protein-protein interaction mainly focused on HPV early proteins (E2, E5, E6, and E7) from 12 reference cutaneous and mucosal HPV. Our strategy combines Y2H with large scale validation assays in human cells, such as biocapture experiments monitored with luciferase activity quantification and a new protein fragment complementation assay (PCA) based on Renilla luciferase. We develop also a TAP-TAG/mass spectrometry approach that can provide key information about complex molecular assemblies. Bioinformatics approaches are used to integrate these viral interactomes into the global human cellular protein networks (Fig 1). The biological impact of some of these interactions is under analysis, such as the pathological consequences of inhibition of the TGF-β1 signaling pathway by HPV E6 and E7 proteins.
These approaches can provide new insights into genetic control of HPV infection as well as shed new light on viral strategies involved in skin and genital carcinogenesis.
Keywords: Viral carcinogenesis, human papillomavirus (HPV), epidermodysplasia verruciformis, predisposition genes, control of HPV infection, biological properties of early viral proteins, yeast two-hybrid screening, viral and human interactomes
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Mendoza J.A., Jacob Y., Cassonnet P., and Favre M (2006). The human papillomavirus type 5 E6 oncoprotein represses TGF-beta signaling pathway by binding to SMAD3. J. Virol. 80 : 12420-12424
Lazarczyk M, Pons C, Mendoza JA, Cassonnet P, Jacob Y, and Favre M. (2008). Regulation of cellular zinc balance as a potential mechanism of EVER-mediated protection against pathogenesis by cutaneous oncogenic human papillomaviruses.J. Exp. Med.205:35-42
Thierry F and Demeret C. (2008). Direct activation of caspase 8 by the proapoptotic E2 protein of HPV18 independent of adaptor proteins. Cell Death Diff 15:1356-1363.
Lazarczyk M and Favre M. (2008) . The role of Zn2+ ions in host-virus interactions. J. Virol 82:11486-11494.
Activity Reports 2009 - Institut Pasteur
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