SK1 Inhibition as a Regulator Of a Renal Cell Proliferation and beta-Catenin Distribution

UDOVIN LD; FAVALE NO; STERIN-SPEZIALE NB

Rosario

Congreso; Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology Research; 2014

SAIB

Sphingosine Kinase (SK) is a key regulator enzyme that regulates sphingosine-1-Phosphate (S1P) synthesis, a lipid involved in several cellular processes. SK is a key regulator of sphingolipids de novo synthesis, for these reasons 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 (DHS), a SK1 inhibitor. SK inhibition induced a decrease in cell number after 24 hs of incubation with no alteration in cell viability. It has been reported that intranuclear beta-catenin translocation is involved in cell cycle modulation. So, we evaluated β-catenin distribution by inmunofluorescence. In control cells, beta-catenin was distributed mainly at cell-cell contacts, whereas DHS treatement induced a beta-catenin intranuclear distribution. SK1 inhibition induces an increase in de-novo ceramide synthesis. To study if beta-catenin mobilization was due to a ceramide increase, we used myriocine (Myr - de novo synthesis inhibitor) that avoid Cer accumulation. Myr prevented DHS effect suggesting ceramide was involved in this process and beta-catenin intranuclear distribution. In summary we propose that SK1 inhibition modulates cell cycle by mechanism that involves beta-catenin intranuclear distrubution as consequence of ceramide accumulation.