PREMATURE P34(CDC2) ACTIVATION REQUIRED FOR APOPTOSIS

Activation of the serine-threonine kinase p34cdc2 at an inappropriate time during the cell cycle leads to cell death that resembles apoptosi s. Premature activation of p34cdc2 was shown to be required for apopto sis induced by a lymphocyte granule protease. The kinase was rapidly a ctivated and tyrosine dephosphorylated at the initiation of apoptosis. DNA fragmentation and nuclear collapse could be prevented by blocking p34cdc2 activity with excess peptide substrate, or by inactivating p3 4cdc2 in a temperature-sensitive mutant. Premature p34cdc2 activation may be a general mechanism by which cells induced to undergo apoptosis initiate the disruption of the nucleus.