Changes In Ceramide Metabolism Contribute To MDCK Cell Differentiation

PESCIO LG; LOPEZ VG; GERARDI GM; FAVALE NO; SANTACREU B; STERIN SPEZIALE NB

Bari

Congreso; 54th International Conference on the Bioscience of Lipids; 2013

ICBL

Ceramide (Cer) and Glucosylceramide (GlcCer) are SPHINGOLIPIDS involved in many important cellular processes. We have previously demonstrated that hypertonicity induces an increase in the synthesis of sphingolipids. Among the sphingolipids, we have reported that GlcCer derived from recycled Cer is essential in MDCK cell differentiation induced by hypertonicity. Cer species are synthesized by six Cer synthases (CerS1-6), each one with different acyl CoA substrate specificity. The aim of this study was to evaluate the expression of CerS1-6, and the different species of Cer and GlcCer during MDCK cell differentiation. Confluent MDCK cells were cultured under isotonicity (control, non-differentiated cells) or subjected to hypertonic media to induce differentiation. RT-PCR analyzes showed that MDCK cells express three of the six isoforms of CerS: CerS2, CerS4 and CerS6. There were no significant differences in CerSs expression between control and hypertonicity-cultured cells. In this study we also analyzed the fatty acid composition of Cer and GlcCer species by MALDI-TOF MS. We identified four mayor species of Cer (C16:0, C24:1, C24:0 and C22:0) and six mayor species of GlcCer (C16:0, C24:1, C24:0, C22:0, C20:0 and C18:0). These results are in accordance with the profile of CerS expression detected in MDCK cells. Although the composition of sphingolipids was the same under both conditions, we found that C16:0 Cer and C16:0 GlcCer have the highest relative intensity in control cells, whereas hypertonicity-cultured cells showed an increase in the relative intensity in C24:0 Cer and C24:0 GlcCer. These changes in Cer metabolism of MDCK cells could provide new clues to understanding the mechanism of renal epithelial cell differentiation.