SK1 IS A SHARP REGULATOR OF RENAL EPITHELIAL CELL PROLIFERATION AND G1-G0 CELL CYCLE TRANSITION.

UDOVIN LD; SANTACREU BJ; STERIN DE SPEZIALE NB; FAVALE NO

Iguazú

Congreso; 56th international conference of the Bioscience of lipids (ICBL); 2015

Universidad nacional de córdoba, universidad nacional de quilmes

Sphingosine Kinase (SK) is a key regulator enzyme that regulates sphingosine-1-Phosphate (S1P) synthesis converting sphingosine to S1P by the addition of a phosphate group at its primary hydroxyl group. S1P is an indispensable lipid second messenger that regulates diverse cellular processes. It has been characterized as a dual function signaling molecule, with the ability to activate in a selective manner different effectors on the basis of subcellular localization. S-1-P exerts its actions extracellularly by binding to five different S-1-P receptors (S1PRs), which are differentially expressed based on tissue type. The S1PRs couple to a variety of G-proteins to regulate diverse biological functions ranging from differentiation, migration, and mitogenesis to effector functions, such as proinflammatory mediator synthesis. Alternatively, S-1-P can act through unidentified intracellular targets, resulting in regulation of cell growth and survival, cytoskeletal changes, cellular motility. For these reason we evaluate the importance of SK activity in renal epithelial cell cycle modulation. For this purpose, MDCK cells were cultured at low density, to allow cell cycle progression and were treated with D,L-threo-dihydrosphingosine (tDHS), a SK1 inhibitor. SK inhibition induced a decrease in cell number after 24 h of incubation with no alteration in cell viability. Besydes treatment for 24 h with an tDHS caused a clear cell cycle arrest in G0/G1 phase. In order to estimate the proportion of cells in G0 respect to G1 phase cell cycle, the method of simultaneous staining of RNA and DNA with acridine orange was used, showing an increase of the cell proportion in G0 phases in trated with tDHS for 48 and 72 h, but in treated cells with tDHS for 24 h as in abscense of inhibitor the G0 phase was not observed. In summary, the SK inhibition produce cell number decrease, cell cycle arrest and promoting the G1-G0 cell cycle transition.