Fig. 3. N-SMase2-generated ceramide is important in cyclopamine-induced cell death in Daoy cells.
(A-B) Ceramide (A) and SM (B) in response to cyclopamine (10μg/mL), in the absence/presence of siRNAs targeting nSMase1 or nSMase2, were measured in Daoy cells by LC/MS-MS. SCR-siRNA-treated cells were used as controls. (C) Effects of downregulation of nSMase2 versus nSMase1 with siRNAs on cell viability were determined with trypan blue exclusion assay. (D) Roles of nSMase2/ceramide in the induction of apoptosis were examined with trypan blue exclusion assay after transfection of Daoy cells with vectors containing cDNAs of the wt or catalytically inactive mutant of N-SMase2, compared with vector only transfected cells. Ectopic expression of wt or mutant N-SMase2-V5 was confirmed by measurement of SMase activity (E) and Western blotting (F) with anti-V5 antibody (as duplicates) in Daoy cells as compared with vector-transfected controls. Actin was used as a loading control in F (bottom).