SPHINGOSINE KINASE 2 (S1PR2) EXPRESSION AND LOCALIZATION IS ESSENTIAL IN THE EPITHELIAL-MESENCHIMAL TRANSITION OF RENAL EPITHELIAL CELLS

PALAVECINO, AGUSTÍN; LOIÁCONO, GERMÁN; ROMERO, DANIELA; PESCIO, LUCILA G; FAVALE, NICOLAS

Rosario

Congreso; LIX Annual Meeting SAIB 2023; 2023

Sphingosine-1-phosphate (S1P) is a bioactive lipid formed by the action of sphingosine kinases 1 and 2 (SK1 and SK2), which can modulate physiological processes such as cellular differentiation and de-differentiation. The de-differentiation process of epithelial cells is known as epithelial-mesenchymal transition (EMT). EMT is a dynamic process by which fully differentiatedepithelial cells can acquire a mesenchymal phenotype. During EMT, cell adhesion and apical-basal polarity are lost, and the cytoskeleton is reorganized. Previous results from our laboratory showed that fully differentiated Madin-Darby canine kidney (MDCK) cells at the wound edge can undergo EMT during wound healing to acquire their migratory profile by the activation of the S1P specific receptor 2 (S1PR2)/ERK1/2 pathway. However, less is known about the SK isoform involved in S1P production and EMT activation. Therefore, we used our study model to establish which SK isoforms participate in the de-differentiation and migration process. We found that the pharmacological inhibition of SK2 prevents changes in EMT markers, such as actin cytoskeleton rearrangement and adherent junction (AJ) disassembly (E-cadherin/beta and alpha catenin plasma membrane co-distribution). Then we evaluated SK2 expression and subcellular localization. We found an increase in SK2 expression in cells adjacent to the wound edge (N zone cells - first ten rows of cells adjacent to the wound) as compared to cells away from the wound edge (F zone cells – ten to fifteen rows of cells adjacent to the N zone). We also observed that SK2 was localized in the Golgi apparatus in the F zone but acquired a vesicle-like distribution compatible with lipid droplets in the N zone. We further evaluated the SK1 effect on EMT and found that SK1 inhibition also prevented changes in EMT markers, as observed for SK2 inhibition. Interestingly, we found that SK1 inhibition blocked SK2 redistribution, which suggests SK1 involvement in SK2 mobilization. Similar results were observed when S1PR2 was inhibited. These results suggest that the relocalization of SK2 is acentral event in EMT and depends on previous S1PR2 activation by S1P synthesis by SK1. These findings highlight the versatility and complexity of sphingolipids in cellular fate determination