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.