Genetics, Papillomavirus and Human Cancer  


  HEADDr FAVRE Michel / mfavre@pasteur.fr
  MEMBERSBOULABIAR Manel / Dr DEMERET Caroline / Dr JACOB Yves / Dr MENDOZA José / NEVEU Grégory / ROLLOY Caroline / Dr VUILLIER Françoise / CASSONNET Patricia
PONS Christian / DELAIRE Marie-Claire / RIBIERRE Hélène


  Annual Report

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 is characterized by an abnormal susceptibility to a specific group of viruses (EV HPV), including HPV5. We have demonstrated that mutations in either of two genes (EVER1 and EVER2) with unknown functions confer the sensitivity to EV HPV. It can be assumed that they play a role in the permissivity of keratinocytes to EV HPV, that are harmless in the general population, or in the triggering of immune response for eradication of lesions. EV is thus a good model to analyze genetic control of HPV infection. Our aim is to characterize the functions of EVER1 and EVER2 proteins in normal and infected cells and to analyze the role of viral early proteins in the HPV life cycle and in the malignant transformation associated with oncogenic HPV.

EVER protein functions.

We have shown that EVER1 and EVER2 interact with the zinc transporter ZnT-1 and form a complex located in the endoplasmic reticulum. The complex influences the zinc concentration in nucleolus and down regulates expression of transcription factors (MTF-1, c-Fos, c-Jun). Some of these factors are needed for the transcription of viral genome. In addition, we showed that HPV16 E5 protein binds to EVER and ZnT-1 and blocks their negative regulation. The lack of a functional E5 protein encoded by EV HPV genome may account for host restriction of these viruses. We currently study the impact of EVER mutations on the control of immune response by analysis of cytokine expression in lymphoblastoid cell lines and keratinocytes obtained from EV patients and healthy relatives. We also analyze whether zinc homeostasis is modulated only by EVER/ZnT-1 complex or whether other cell proteins may interact with the complex. Finally we investigate in keratinocytes the role of EVER/ZnT-1 complex on the transcription of the early viral genes (E1, E2, E6, and E7) and on the late steps of the viral life cycle.

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. Our strategy is based on the identification of cellular proteins interacting with E2, E6 and E7 proteins of 12 reference cutaneous and mucosal HPV by yeast 2-hybrid and TAP-TAG/mass spectrometry approaches. Protein-protein interaction should lead to analysis of signaling pathways altered by viral expression and give some clues on strategies developed by low risk and high risk HPV for their replication and malignant conversion of infected keratinocytes. Using high throughput yeast 2-hybrid screening, more than 1700 interactions have been detected for E6 or E7 that putatively modify cell signaling pathways or activity of cell proteins involved in gene transcription and other vital properties for the cell. We currently analyze and validate some of these interactions in mammalian cells. Bioinformatics approaches are used to integrate these viral interactomes into the global cellular protein networks (Fig. 1). Studies are also in progress to analyze consequences on inhibition of the TGF-1 signaling pathway by HPV E6 and E7 proteins as previously shown with the E6 protein of oncogenic HPV5.

These studies should allow a better understanding of genetic control of HPV infection as well as viral strategies involved in skin and genital carcinogenesis.

Keywords: Viral carcinogenesis, human papillomavirus (HPV), predisposition genes, HPV life cycle, epidermodysplasia verruciformis, control of HPV infection, biological properties of early viral proteins

Gpc.jpg

Cytoscape representation of the E6 and E7 interactome merged with the human interactome (HPRD release-09/2007) revealing the high degree of connectivity of HPV targeted proteins suggestive of their functional importance in the cellular network.



  Publications

Laffort C, Le Deist F, Favre M, Caillat-Zucman S, Radford-Weiss I, Debre M, Fraitag S, Blanche S, Cavazzana-Calvo M, de Saint Basile G, de Villartay J-P, Giliani S, Orth G, Casanova J-L, Bodemer C, and Fischer A (2004). Severe cutaneous papillomavirus disease after haemopoietic stem-cell transplantation in patients with severe combined immune deficiency caused by common γc cytokine receptor subunit or JAK-3 deficiency. The Lancet 363: 2051-2054.

Herrick J, Conti C, Teissier S, Thierry F, Couturier J, Sastre-Garau X, Favre M, Orth G, and Bensimon A (2005). Genomic organization of amplified MYC genes suggests distinct mechanisms of amplification in tumorigenesis. Cancer Res 65: 1174-1179.

Nonnenmacher M, Salmon J, Jacob Y, Breitburd F, and Orth G (2006). Papillomavirus E8 protein is essential for wart formation and provides new insights into viral pathogenesis. J. Virol. 80 : 4890-4900.

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. (2007). Regulation of cellular zinc balance as a potential mechanism of EVER-mediated protection against pathogenesis by cutaneous oncogenic human papillomaviruses. J. Exp. Med., in press.





Activity Reports 2007 - Institut Pasteur
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