Roles for microtubule and microfilament cytoskeletons in animal cell cytokinesis

Microtubule and microfilament cytoskeletons play key roles in the whole process of cytokinesis. Although a number of hypotheses have been proposed to elucidate the mechanism of cytokinesis by microtubule and actin filament cytoskeletons, many reports are conflicting. In our study, combining the cytoskeletons drug treatments with the time-lapse video technology, we retested the key roles of microtubule and actin filament in cytokinesis. The results showed that depolymerization of microtubules by Nocoda- zole after the initiation of furrowing would not inhibit the furrow ingression, but obviously decrease the stiffness of daughter cells. Depolymerizing actin filaments by Cyto- chalasin B before metaphase would inhibit the initiation of furrowing but not chromosome segregation, resulting in the formation of binucleate cells; however, depolymerizing actin filaments during anaphase would prevent furrowing and lead to the regress of established furrow, also resulting in the formation of binucleate cells. Further, depolymerizing microtubules and actin filaments simultaneously after meta- phase would cause the quick regress of the furrow and the formation of binucleate cells. From these results we propose that a successful cytokinesis requires functions and coordina- tion of both the microtubule and actin filamentcytoskeletons. Microtubule cytoskeleton may function in the positioning and initiation of cleavage furrow, and the actin filament cy- toskeleton may play key roles in the initiation and ingression of the furrow.

Microtubule and microfilament cytoskeletons play key roles in the wholeprocess of cytokinesis. Although a number of hypotheses have been proposed to elucidate themechanism of cytokinesis by microtubule and actin filament cytoskeletons, many reports areconflicting. In our study, combining the cytoskeletons drug treatments with the time-lapse videotechnology, we retested the key roles of microtubule and actin filament in cytokinesis. The resultsshowed that depolymerization of microtubules by Nocodazole after the initiation of furrowing wouldnot inhibit the furrow ingression, but obviously decrease the stiffness of daughter cells.Depolymerizing actin filaments by Cytochalasin B before metaphase would inhibit the initiation offurrowing but not chromosome segregation, resulting in the formation of binucleate cells; however,depolymerize actin filaments during anaphase would prevent furrowing and lead to the regress ofestablished furrow, also resulting in the formation of binucleate cells. Further, depolymerizingmicrotubules and actin filaments simultaneously after metaphase would cause the quick regress of thefurrow and the formation of binucleate cells. From these results we propose a successfulcytokinesis requires functions and coordination of both the microtubule and actin filamentcytoskeletons. Microtubule cytoskeleton may function in the positioning and initiation of cleavagefurrow, and the actin filament cytoskeleton may play key roles in the initiation and ingression ofthe furrow.