Cleavage of lamin-like proteins in in vivo and in vitro apoptosis of tobacco protoplasts induced by heat shock

Apoptosis in heat shock-treated tobacco protoplasts was evidenced by DNA fr agmentation, flow cytometric analysis and activation of caspase 3-like prot ease, Furthermore, an in vitro apoptosis system was established which repro duced the apoptotic events, Western blotting analysis using an antibody aga inst lamin A and C showed that in both in vivo and in vitro systems lamin-l ike proteins mere cleaved into a 35-kDa fragment, and that lamin-like prote in degradation precedes DNA fragmentation. Moreover, we found a 22.8-fold i ncrease in caspase 6-like activity in cytosol of heat-treated protoplasts a s compared with the control. (C) 2000 Federation of European Biochemical So cieties. Published by Elsevier Science B.V. All rights reserved.