INVIVO INHIBITION OF CYCLIN-B DEGRADATION AND INDUCTION OF CELL-CYCLEARREST IN MAMMALIAN-CELLS BY THE NEUTRAL CYSTEINE PROTEASE INHIBITOR N-ACETYLLEUCYLLEUCYLNORLEUCINAL
Sw. Sherwood et al., INVIVO INHIBITION OF CYCLIN-B DEGRADATION AND INDUCTION OF CELL-CYCLEARREST IN MAMMALIAN-CELLS BY THE NEUTRAL CYSTEINE PROTEASE INHIBITOR N-ACETYLLEUCYLLEUCYLNORLEUCINAL, Proceedings of the National Academy of Sciences of the United Statesof America, 90(8), 1993, pp. 3353-3357
The cytotoxic neutral cysteine protease inhibitor N-acetylleucylleucyl
norleucinal (ALLN) inhibits cell-cycle progression in CHO cells, affec
ting the G1/S and metaphase-anaphase transition points, as well as S p
hase. Mitotic arrest induced by ALLN is associated with the inhibition
of cyclin B degradation. At mitosis-inhibiting concentrations of ALLN
, cells undergo nuclear-envelope breakdown, spindle formation, chromos
ome condensation, and congression to the metaphase plate. However, nor
mal anaphase events do not occur, and cells arrest in a metaphase conf
iguration for a prolonged period. Steady-state levels of cyclin B incr
ease to greater than normal mitotic levels, and cyclin B is not degrad
ed for an extended period. Histone H1 kinase activity remains elevated
during mitotic arrest. Duration of mitotic arrest depends on ALLN con
centration; high concentrations (>50 mug/ml) produce a prolonged mitot
ic arrest, whereas at lower concentrations, cells are transiently dela
yed through mitosis (up to 4-12 hr), after which they undergo aberrant
cell division resulting in randomly sized daughter cells containing v
ariable amounts of DNA. Cyclin B degradation fails to occur, and histo
ne H1 kinase remains activated for the duration of mitotic arrest at a
ll ALLN concentrations.