Differential expression of the Disc large polarity protein during the oncogenesis associated to Human Papillomavirus infections

DIZANZO M. P., MARZIALI F., LEIVA S., BRUNET AVALOS C., CAVATORTA A. L., GARDIOL D

Ciudad Autónoma de Buenos Aires

Workshop; Frontiers in Bioscience 3; 2018

Instituto de Investigación en biomedicina de Buenos Aires

The tumour processes are related to the deregulation of cellular polarity proteins which assure the correct division, morphology and cell proliferation. High-risk oncogenic human papillomaviruses (HPV) are related to the development of cervical cancer. The HPV E6 viral oncoprotein is able to interact with the PDZ domains present in polarity regulators. In particular, the human Disc large protein (DLG1), located at the adherent junctions, is affected during HPV-mediated tumour development. The expression of DLG1 in organotypic cultures expressing E6/E7 HPV oncoproteins results in a redistribution of DLG1 from the cell borders to the cytoplasm, as well as an increase in its levels. These findings were in agreement with previous studies using biopsies of precursor lesions of cervical carcinoma. In order to understand the molecular mechanisms involved in this deregulation of DLG1, we performed a series of analyses. We studied the expression of DLG1 in the presence of HPV E6 by immunofluorescence, being able to detect the relocalization of DLG1 from the cell contacts to the cytoplasm. We also found that an overexpression of DLG1 causes an impact in the localization of E6 in a PDZ-dependent manner. To corroborate the binding between DLG1 and E6 we performed FRET experiments and we detected for the first time a direct interaction between both proteins within the cell. We also studied the contribution of E7 on the expression of DLG1. We observed that the dual expression of E6 and E7 induces a delocalization and an increase in DLG1 levels in the insoluble cell fraction. These results suggest that viral oncoproteins promote the stabilization of DLG1 in the cytoplasm with probable changes in its oncosuppressive functions. These data contribute to the molecular understanding of the alteration of cell polarity during the oncogenesis.