D-meth accelerates replicative senescence.
(A-D) Effects of D-meth (1 mM, closed bars) or vehicle (open bars) on (A) senescence-associated -galactosidase (-Gal) staining, (B) cell morphology, (C) ceramide levels, and (D) expression of CerS5 mRNA in primary MEF cultures. (E-F) Effects of D-meth on replicative capacity assessed by (E) [3H]-thymidine incorporation into DNA and (F) number of cumulative population doublings (vehicle: open squares, D-meth: closed squares). (g-j) Effects of D-meth (M, 1 mM), L-cycloserine (L-CS, 30 μM) and combination of D-meth plus L-CS on transcription of senescence-associated markers: (G) p53, (H) p21, (I) IL-6 and (J) TNF-α. (K, L) Effects of L-CS (30 μM), fumonisin B1 (FB1, 50 μM) and cell-permeant C8 ceramide (10 μM) on -Gal expression elicited by D-meth (M, 1 mM). ANOVA followed by Bonferroni post hoc test: *P<0.05, **P<0.01, ***P<0.001, vs. vehicle; $P<0.05, $$$P<0.001, vs vehicle at passage 1. ##P<0.01, vs D-meth.
