Role of Sphingosine-1-Phosphate Receptor 3 in Epithelial Cell Differentiation

TARALLO E; ROMERO DJ; SANTACREU BJ; PESCIO LG; FAVALE NO

Salta

Congreso; LV Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology Research (SAIB) and XIV PABMB; 2019

SAIB-PABMB

Madin-Darby canine kidney cells (MDCK) acquired a differentiated phenotype when they are cultured in hypertonic medium. Previous works from our lab have demonstrated that sphingolipid metabolism is involved in such differentiation process. One of the most active sphingolipid is sphingosine-1-phosphate (S1P), that has been classically associated with the induction of a proliferative phenotype and anti-apoptotic activity. However, the participation of S1P in cell differentiation is not well understood. S1P can act both intracellularly as second messenger and extracellularly as ligand for cell surface receptors (S1PRs). We have reported that S1P levels decreases during transition to the differentiated state and S1P acts by its receptors. In this work we evaluated whether changes in the expression and/or localization of S1PRs are involved in the differentiation process. Immunofluorescence studies showed that during cell differentiation S1PR3 was located in intracellular vesicles. However, S1PR3-vecicles changed their intracellular localization depending on cell differentiation state. In proliferative state S1PR3 was in all the cytoplasm, but was relocated to sub-apical distribution during differentiation process. At the final stage of cellular differentiation, where apical domain and primary cilium were present, S1PR3-vecicles signal decreased. Moreover, pharmacological inhibition of S1PR3 accelerated the apical membrane establishment. These results suggest that S1PR3 need to be inactivated/degraded for final epithelial cell differentiation, which propose a possible new function for the S1P/S1PR3 pathway in phenotypical epithelial cell differentiation.