PARP and CD3/TCR ζ-chain, but not DFF45, are cleaved during Lptn-induced apoptosis.

(A) Total proteins of cells activated for days 0.5 to 4 with the indicated stimuli were analyzed by Western blotting for detection of substrates and PI3K control expression, using the antibodies, as already described. Arrows indicate the full-length forms of the substrates, except for p85 of PARP corresponding to a cleaved product. No expression variation for both PARP and CD3 ζ-chain were observed on CD3 and CD28 costimulation, in presence or absence of Lptn, and are not shown. This experiment was performed at least 3 times, except for 2 times in the case of DFF45. As a positive control, on CD3 and CD28 costimulation, the presence of Lptn induced a 2-fold reduction in DFF45 expression. (B) Kinetics of CD3/TCR ζ-chain processing by Lptn. The graph represents the relative levels of the ζ-chain/PI3K signal ratio induced by the indicated stimuli, with SD indicated by error bars. Each mean level is representative of 4 independent experiments. ▪, CD3; ■, CD3 plus Lptn.