Role of sphingolipid metabolism in MDCK cells transition from polarized to differentiation phenotype

FAVALE NICOLAS; SANTACREU BRUNO; MARÍA GABRIELA MÁRQUEZ; NORMA STERIN-SPEZIALE

Potrero de los Funes - San Luis

Congreso; XLVII REUNIÓN ANUAL DE LA SOCIEDAD ARGENTINA DE INVESTIGACIONES BIOQUÍMICAS Y DE BIOLOGÍA MOLECULAR (SAIB); 2011

SOCIEDAD ARGENTINA DE INVESTIGACIONES BIOQUÍMICAS Y DE BIOLOGÍA MOLECULAR (SAIB)

Cell-Cell adhesion, by establishment of adherens junctions (AJ) is an early event for epithelial cell polarization/differentiation and maintenance of cell differentiation. We have previously demonstrated that AJ complexes are located in a sphingomyelin enriched lipid membrane domain. We aim to study the importance of SM synthesis in the acquisition of the polarized-differentiated MDCK cells phenotype. Confluent MDCK cells were submitted to hypertonicity and concomitantly treated or not (control) with different concentration of D609, an SM synthase inhibitor. After 48 h, cell phenotype was visualized by confocal microscopy of actin cytoskeleton and cell?cell adhesion structures. As inhibitor concentration rise, the cell?cell adhesions were impaired, and the characteristic polarized phenotype of the cells was lost. First cells appeared lengthened, and thereafter acquired a fibroblast like phenotype. E-cadherin signal decreased and appeared discontinued. Polymerized actin seemed not to be altered, cortically located and increased stress fibers were observed at the highest D609 concentration. Moreover, we determined that augment in the SMS1/SMS2 ratio was involved in the cell-cell adhesion instauration. From these results we suggest that, instead to differentiate, polarized MDCK cells undergo mesenchymal transition when induced to differentiate in a condition of inhibition of SM synthesis.