Inhibition of sphingomyelin synthase 1 activity promotes an epitelial-mesenchymal transition (EMT) in differentiated collecting duct cells

BRANDAN YR; GUAYTIMA, EV; FAVALE NO; PESCIO LG; STERIN SPEZIALE NB; MARQUEZ MG

CABA

Congreso; II Reunión Conjunta de Sociedades de BioCiencias. Ciudad Autónoma de Buenos Aires; 2017

SAIB-SAIC-SAI-SAA-SAB-SAB-SAFE-SAFIS-SAH-SAP

Abstract: In Epithelial-Mesenchymal Transition (EMT), contrary to Mesenchymal-Epithelial Transition (MET), cells lose their epithelial phenotype and acquire the characteristics of mesenchymal cells. EMT normally occurs during embryonic development, and in adult tissues is activated during in ammation, tissue regeneration, and it has also been related with brosis and cancer. The sphingomy- elin (SM) synthase 1 (SMS1) participates during the nal step of SM synthesis. In previous works, we have demonstrated that the inhibition of SMS1 activity induces the loss of cell-cell adhesions of collecting ducts (CD), and it also affects their morphology. Taking into account that these characteristics are similar to those described for EMT, we investigate whether the SMS1 inhibition could induce this process. To this end, primary cultures of differentiated CD cells were incubated for 24 h with D609, a SMS1 inhibitor. By immuno- cytochemistry and immunoblot we analyzed the expression of the mesenchymal cells markers: vimentin and α-smooth muscle actin (α-SMA). In basal conditions, CD cells formed monolayers with low expression of vimentin, and almost null in α-SMA. Overlapping cells with broblastoid morphology, which strongly express both proteins, were also observed. After D609 treatment, the number of CD ex- pressing vimentin and α-SMA increased, denoting a de novo synthe- sis of α-SMA. The amount of overlapping cells was also increased. The immunoblot analysis showed a correlative increased in the level of both proteins. Tacking into account the changes observed in cell morphology and de novo synthesis of α-SMA, we suggest that the inhibition of SMS1 activity could alter the equilibrium between EMT- MET, generating myo broblasts from preexisting CD cells, because of the inability to form cell-cell adhesions. In this context, we propose that SM synthesis is important to keep the EMT-MET equilibrium, and we highlight the activity of SMS1 as a modulator of this process.