Implication of sphingolipid metabolismin renal epithelial cell linedifferentiation

BRUNO J. SANTACREU; NORMA BEATRRIZ STERIN; NICOLáS O FAVALE

Ciudad Autonoma de Buenos Aires

Congreso; Reunión anual de SAIB; 2013

SAIB

Sphingosine 1-Phophate (S1P) is an important sphingolipidmediator in cell fate,synthetized by Sphingosine Kinase (SK).We study the involvement of SK activity in the establishment of differentiated phenotype of MDCK cells induced by external hypertonic media. For this end, confluent MDCK cells were subjected to hypertonic medium withthe concomitant addition or not (control) of D,L-threo-dihydrosphingosine (DHS) as an SK inhibitor. After 48 h of incubation, thecell phenotype was visualized by fluorescence microscopy, evaluating actin cytoskeleton and Adherens Junction (AJ) formation. DHS treatmentinducesâ-catenin redistribution from plasma membraneto intracellular localizationand actin cytoskeleton reorganization, resulting in disassembling of AJ. SK inhibition alsoinduces an increase in de novo sphingolipid synthesis with Ceramide (Cer) accumulation. In order to evaluate whether AJ disassembly is due to Cer accumulation, Myriocin (Myr),an inhibitor of the novo synthesis,was used. Myrtreatment recovers MDCK phenotype,suggesting that the disassembly of AJ due to inhibition of SK activity is an indirect effect produced by Cer accumulation.