Figure 3.

Prevention of CHOP mRNA induction by reconstitution of C16-dh-ceramide generation via expression of wt-CerS6. A–D) Control UM-SCC-22A (22A) cells (lanes 1, 2), and Tet-induced (+Tet) UM-SCC-22A cells expressing either WT (lanes 3, 4) or catalytically inactive mutant (H212A) CerS6 (lanes 5, 6) were transfected with either Scr or CerS6 siRNA (50 nM) for 48 h, and expression levels of CerS6 or actin proteins (A) were detected by Western blotting. Then, their effects on ceramide levels were measured by LC/MS (B), CHOP mRNA was measured by Q-PCR (C), and activation of caspase 3 was measured by activity assay (D). E) Tet-induced cells expressing CerS1 or CerS6 were transfected with siRNA as in A, and CHOP mRNA was measured by Q-PCR. Bars represent means ± sd from 3 experiments. *P < 0.05.