ENDOGENOUSLY SYNTHESIZED SPHINGOSINE-1-PHOSPHATE TRIGGERS CELL EXTRUSION IN MDCK CELLS

LUCILA GISELE PESCIO; BRUNO JAIME SANTACREU; NORMA BEATRIZ STERIN-SPEZIALE; ROMERO, DANIELA JUDITH; FAVALE, NICOLÁS O.

Online

Congreso; Congreso Conjunto SAIB-SAMIGE 2020; 2020

One of the mechanisms that ensure epithelial integrity is cell extrusion, a process to remove dying or surplus cells while maintaining the epithelium barrier. This process is triggered by sphingosine-1-phosphate (S1P) which activate S1P receptor 2 and produces the contraction of an actomyosin ring in the neighboring cell. The contraction squeezes the cell out apically while drawing together neighboring cells and preventing any gaps to the epithelial barrier. Previously, we demonstrated that sphingosine kinase 2 (SphK2) is involved in cell in MDCK differentiated cells. However, the origin of the S1P is controversial. The goal of this work was to study the source of the S1P synthesis production that triggers cell extrusion. For this end, we developed a microscopy fluorescence-based assay for monitoring S1P endogenous production, based on a shift in the NBD-Sph spectral emission after SphK activity to form NBD-S1P. MDCK differentiated cells showed a very low NBD-S1P signal level, whereas, extruding cells in an upper plane of the monolayer showed a significant increase of NBD-S1P signal. On the other hand, we found a change in the SphK2 subcellular localization that could be link to the S1P synthesis. The results show that cell extrusion is triggered by the single-cell synthesis of S1P, synthesized by sphingosine kinase 2 (SphK2) of the extruding cell itself.