INHIBITION OF SPHINGOMYELIN SYNTHASE 1ACTIVITY PROMOTES AN EPITHELIAL-MESENCHYMAL TRANSITION (EMT) IN DIFFERENTIATED COLLECTING DUCT CELLS

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

Buenos Aires

Congreso; Reunión conjunta de sociedades de biociencias; 2017

In Epithelial-Mesenchymal Transition (EMT), contrary toMesenchymal-Epithelial Transition (MET), cells lose their epithelialphenotype and acquire the characteristics of mesenchymal cells.EMT normally occurs during embryonic development, and in adulttissues is activated during inflammation, tissue regeneration, andit has also been related with fibrosis and cancer. The sphingomyelin(SM) synthase 1 (SMS1) participates during the final step ofSM synthesis. In previous works, we have demonstrated that theinhibition of SMS1 activity induces the loss of cell-cell adhesions ofcollecting ducts (CD), and it also affects their morphology. Takinginto account that these characteristics are similar to those describedfor EMT, we investigate whether the SMS1 inhibition could inducethis process. To this end, primary cultures of differentiated CD cellswere incubated for 24 h with D609, a SMS1 inhibitor. Byimmunocytochemistryand immunoblot we analyzed the expression of themesenchymal cells markers: vimentin and á-smooth muscle actin(á-SMA). In basal conditions, CD cells formed monolayerswith lowexpression of vimentin, and almost null in á-SMA. Overlapping cellswith fibroblastoid morphology, which strongly express both proteins,were also observed. After D609 treatment, the number of CD expressingvimentin and á-SMAincreased, denoting a de novo synthesisof á-SMA. The amount of overlapping cells was alsoincreased.The immunoblot analysis showed a correlative increased in the levelof both proteins. Tacking into account the changes observed in cellmorphology and de novo synthesis of á-SMA, wesuggest that theinhibition of SMS1 activity could alter the equilibrium between EMTMET,generating myofibroblasts from preexisting CD cells, becauseof the inability to form cell-cell adhesions. In this context, weproposethat SM synthesis is important to keep the EMT-MET equilibrium,and we highlight the activity of SMS1 as amodulator of this process