Cell polarity disruption during HPV infections

BUGNON VALDANO, MARINA; MARZIALI, FEDERICO; BARBIERI, GUIDO; FACCIUTO, FLORENCIA; BOCCARDO, ENRIQUE; CAVATORTA, ANA LAURA; GARDIOL, DANIELA

Trieste

Congreso; ICGEB DNA Tumour Virus Meeting 2015; 2015

ICGEB

Cell polarity depends on the asymmetric and highly regulated distribution of proteins and lipids. Loss of cell polarity and disruption of cell junctions is one of the main features of carcinogenic processes. We are interested in different mechanisms that regulate polarity proteins expression, mainly considering carcinogenic processes associated with Human papillomaviruses (HPV) infections. Several PDZ polarity proteins are known targets of HPV. We are focused on the regulation of DLG1 and PAR3 polarity proteins, having both structural and signaling functions. Their expression is altered in several tumors but the mechanisms beyond these alterations remain unknown.To study the regulation of polarity proteins specifically during HPV infections, we generated organotypic RAFT cultures, reproducing in vitro the process of epithelial differentiation. In particular, we developed RAFT cultures expressing E7 alone or together with E6 protein from HPV18 (high risk) and HPV11 (low risk), and therefore closely mimicking HPV-host interaction. We confirmed the expression of the corresponding viral transcripts by RT-PCR. Then, we analyzed the expression of known HPV cellular targets by Western Blot (WB) and Immunohistochemistry (IHC). Remarkably, clear changes in the distribution along the epithelium as well as in the subcellular localization of DLG1 were observed when expressing the viral proteins. The effect was more striking for the high risk HPV proteins where DLG1 was completely lost form the cell border. It was also observed alteration is DLG1 abundance with an increase in the protein levels in raft cultures expressing E7 or E6/E7 proteins from both HPV-11 and HPV 18. Furthermore, by traditional cell culture and WB, we observed that exogenous expression of E7 and E6/E7 proteins (from HPV 18 and HPV 11) in epithelial cells also causes a moderate increase in DLG1 protein level. Although further studies are required to elucidate the specific molecular mechanisms involved in the reported changes in DLG1 expression in the presence of the viral proteins, these observations contribute to understand the changes in the expression of DLG1 observed in cervical lesions, indicating a role for HPV proteins.In addition, we have start analyzing the expression of other polarity cellular target of HPV: PAR3 protein. We found that this protein is also upregulated and misdistributed in the presence of the previous mentioned HPV proteins. These observations indicate a role of HPV proteins in the disturbance of polarity proteins. However, further studies are required to elucidate the specific molecular mechanisms altered in the presence of the viral proteins that eventually induce the reported changes in polarity proteins expression.