EFFECTS OF MEVINOLIN ON CELL-CYCLE PROGRESSION AND VIABILITY OF TOBACCO BY-2 CELLS

Mevinolin, an inhibitor of 3-hydroxy-3-methylglutaryl-CoA reductase, w as used to study the importance of mevalonic acid (MVA) for cell cycle progression of tobacco (Nicotiana tabacom L.) BY-2 cells. After treat ment with 5 mu M mevinolin, the cell cycle progression was completely blocked and two cell populations accumulated (80% in phase G0/G1 and 2 0% in G2/M). The arrest could be released by subsequent addition of MV A. Effects were compared to those caused by aphidicolin, an inhibitor of alpha-like DNA polymerases that blocks cell cycle at the entry of t he S phase. The 80% proportion of mevinolin-treated TBY-2 cells was cl early arrested before the aphidicolin-inducible block. By the aid of a double-blocking technique, it was shown that the mevinolin-induced ce ll arrest of highly synchronized cells was due to interaction with a c ontrol point located at the mitotic telophase/entry G1 phase. Dependin g on the developmental stage, mevinolin induced rapid cell death in a considerable percentage of cells. Mevinolin treatment led to a partial synchronization, as shown by the increase in mitotic index. The follo wing decrease was correlated with the above-mentioned induction of cel l death.