THE EFFECTS OF TAXOL ON THE MICROTUBULE ASSEMBLY IN CULTURED HUMAN FIBROBLAST CELLS
WANG DUAN-SHUN,LIN ZHONG-XIANG YAN YU-XIN,AND WANG KUN-REN (Department of Biology,Beijing Normal University,Beijing) (Department of Cell Biology,Beijing Institute for Cancer Research)
Taxol,a low molecular weight natural plant product,was a resistant which can resist the depolymerization of microtubules by the cold(4℃) and colcemid treatment.This drug stabi- lized labile microtubule and reduced the critical tubulin concentration of the centrosomes to nucleate micro- tubule assembly in vitro.It was a potent promoter of microtubule as- sembly.Evidently taxol promoted the formation of microtubule bundles in cell in a time dependent manner.It caused the alteration of the distribu- tion of the pre-existing CMTG (cyto- plasmic microtubule complex). The centrosomes were separated from nucleus after treatment with colcemid and triton X-100,and the capacity of the centrosomes for organize microtubule assembly was enhanced by 10~(-5) M taxol.When cells entered from G_2 to M phase in the presence of taxcl,they were unable to depoly- merize their interphase microtubules. While in mitosis,no metaphase plates were formed,nor was there any indi- cation of a normal mitotic spindles were presented.Thus,the cells,finally be- came micronucleated cells after treat- ment with taxol.We suggest that the combined use of taxol and inhibitors of tubulin polymerization may provide a useful experimental tool to further investigate organized microtubule as- sembly in vivo.