An interleukin‐1β‐converting enzyme‐like protease is a common mediator of apoptosis in thymocytes

Abstract

Apoptosis was induced in thymocytes using diverse stimuli in order to identify events within a common apoptotic pathway Benzyloxycarbonyl-valinyl-alaninyl-aspartyl fluoromethyl ketone (Z-VAD.FMK), an interleukin-1 beta-converting enzyme (ICE)-like protease inhibitor, inhibited apoptosis assessed by how cytometry, proteolysis of poly (ADP)-ribose polymerase (PARP), an early biochemical marker of apoptosis, and cleavage of DNA to both large kilobase pair fragments (30-50 and 200-300 kbp) and to nucleosomal fragments. Z-VAD.FMK also blocked all the classical ultrastructural features of apoptosis including chromatin condensation to one pole of the nucleus, nucleolar disintegration and cytoplasmic vacuolation. These results suggest the involvement of an ICE-like protease as a common mediator of apoptosis in thymocytes.