IBR   13079
INSTITUTO DE BIOLOGIA MOLECULAR Y CELULAR DE ROSARIO
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Viral factors contributing to cell polarity disruption during HPV-associated carcinogenesis
Autor/es:
FACCIUTO FLORENCIA, BUGNON VALDANO MARINA, CAVATORTA ANA LAURA AND GARDIOL DANIELA
Lugar:
Mendoza
Reunión:
Taller; Curso “2nd Cell Biology Summer Course- Mendoza 2010”; 2010
Institución organizadora:
Institut Curie- IHEM PROBIOL (FCM-UNCuyo-CONICET) Mendoza Argentina
Resumen:
Human papillomaviruses (HPVs) are the causative agents of a number of human cancers, being cervical cancer the most important one. A unique characteristic of the HPV-types associated with tumour development is the presence of a PDZ recognition motif in the carboxy terminus of the viral E6 oncoprotein. PSD-95/Dlg/ZO-1 (PDZ) domains are specialized peptide recognition motifs present in proteins involved in the formation of intercellular junctions and in the control of cell polarity. Cell polarity is a complex process that also implies the correct distribution of membrane Phosphoinositide (PIP) lipids. Moreover, it has been demonstrated that a subset of PDZ proteins interacts with this kind of lipids and this interaction is relevant for the PIP correct distribution. The binding site between PIP and PDZ proteins partially overlaps the binding site of PDZ- binding peptides. It is possible to speculate that E6 could disrupt the interaction between PIPs and PDZ polarity proteins, interfering with the correct localization of PIPs and tight junction complexes, with the consequent disruption of baso-apical polarity. The aim of our study is to analyze these E6 activities and their probable implication in the progression to malignancy in HPV-associated lesions. At a first step, we cloned E6 proteins derived from different HPV types and confirmed their expression by immunofluorescence in both, transient and stable transfection experiments, and using epithelial cells. We want to address how E6 oncoproteins disrupt the tight junction complexes that are crucial for the maintenance of polarity, analyzing the distribution of tight junction proteins in E6-positive cells. We optimized an IFI assay for the analysis of Par-3 protein, a key element of this kind of junctions, showing that in epithelial cells it is localized at the cell-cell interactions, and high risk HPV E6 proteins appears to alter this Par-3 cell localization. The differences in PIP distribution in the presence and absence of E6 proteins are being analyzed by the location of a PIP biosensor, the PH domain of phospholipase-C fused to green fluorescent protein in cell lines expressing the construct. Preliminary results have shown that E6 expression mislocalizes the PIP lipids, reducing their presence at the cell borders.