PTEN ACTIVITY REGULATES TARGETING OF GP135 AND CELL DIFFERENTIATION IN MDCK CELLS

ROMERO DJ; STERIN SPEZIALE NB; SANTACREU BJ; FAVALE NO; PESCIO LG; FRANCISCO MN

Paraná

Congreso; LIV Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology Research; 2018

SAIB

MDCK cell differentiation is characterized by the development of a mature apical membrane enriched in gp135 and primary cilium formation. The correct apical targeting of gp135 is necessary for MDCK cells to organize a single lumen at the apical surface. We have previously demonstrated that the correct localization of PTEN, a key enzyme in the metabolism of the polyphosphoinositides, depends on glycosphingolipid metabolism, and this feature is essential for MDCK cell differentiation. In this study we analyzed the development of primary cilium and the distribution of gp135 in cells cultured under hypertonicity (inductor of cell differentiation) in the presence of SF1670, a selective PTEN inhibitor. MDCK cells stably transfected with GFP- tagged gp135 (gp135 - GFP) cultured under hypertonicity 48 h post - confluence developed a differentiated phenotype with apical accumulation of gp135 and primary cilium, like wild type cells. Interestingly, gp135 - GFP transfected cells cultured under hypertonicity treated with SF1670 revealed aberrant lumens at the lateral domain and mistargeting of gp135 - GFP to this structure, and the same effect was found for endogenous gp135. Furthermore, the treatment with SF1670 also altered primary cilium formation. These effects were observed when SF1670 was added together with hypertonicity, but not when it was added once the cells were already differentiated. In conclusion, the disruption of epithelial cell differentiation induced by PTEN inhibition suggests an interplay between phosphoinositides and glycosphingolipids that govern the correct sorting of polarity proteins.