The correct localization of PTEN in epithelial cells depends on glycosphingolipid metabolism.

FAVALE, NICOLÁS OCTAVIO; MARQUEZ, MARIA GABRIELA; PESCIO, LUCILA GISELE; ROMERO, DANIELA JUDITH; SANTACREU, BRUNO JAIME; STERIN-SPEZIALE, NORMA BEATRIZ

Zurich

Congreso; 58th International Conference on the Bioscience of Lipids; 2017

We have previously demonstrated that Madin-Darby canine kidney (MDCK) cells, a cell line derived from renal collecting ducts, develop a polarized phenotype when they are subjected to hypertonic medium, and we found that glycosphingolipid synthesis is essential in this process. The localization of PTEN, a key enzyme in the metabolism of the polyphosphoinositides, is important in the polarity of epithelial cells. In this study we analyzed the distribution of PTEN in MDCK cells in different experimental conditions. We found that non-differentiated cells cultured under isotonicity showed cytoplasmic localization of PTEN, but when the cells were subjected to hypertonicity developed a mature membrane with apical accumulation of the apical marker gp135 and PTEN concentrated in this membrane domain with a dot ? like distribution. Interestingly, the inhibition of glucosylceramide synthase with D-PDMP or the knockdown of the enzyme disrupted apical membrane development and induced the mislocalization of PTEN and atypical PKC, a key protein that controls cell polarity. Furthermore, cells incubated under hypertonicity in the presence of SF1670, an inhibitor of PTEN, did not develop the polarized phenotype. These results suggest that glycosphingolipids are necessary for the correct localization of PTEN and indicate an important crosstalk between sphingolipid and polyphosphoinositide metabolism.