Overview Cell Structures Cell Migration Cell Division  

Dependence of Cytokinesis on Midzone Microtubules As Detected in Cells Treated with Topoisomerase II Inhibitors

Wheatley et al., Mol. Biol. Cell 9:2173-2184 (1998)

To probe the role of midzone microtubules in cytokinesis, the formation of spindle midzone was blocked by treating Normal Rat Kidney epithelial cells with a topoisomerase II inhibitor, ICRF 187. The treatment inhibits the separation of sister chromosomes and block the creation of midzone space, without affecting microtubule bundle formation in the vicinity of tangled anaphase chromosomes. The organization of midzone microtubules is therefore seriously disrupted by the lack of interzonal space.

Abnormal Cytokinesis in Cells Treated with a Topoisomerase II Inhibitor

While cortical ingression takes place in ICRF 187 treated cells, the site of ingression is often abnormal. This cell forms a twisted furrow away from the equatorial plane as defined by the position of metaphase chromosomes. Recording time, 27 min.

Abnormal Cytokinesis in Cells Treated with a Topoisomerase II Inhibitor

This cell initiates ingression in the proper location as defined by the position of metaphase chromosomes. However, the ingressed region becomes elongated and distorted due to the tangled chromosomes. Recording time, 38 min.

Stimulation of Cortical Ingression upon Interactions with Midzone Microtubules

In cells treated with ICRF 187, microtubule bundles emanate from the chromosomal region during anaphase and extend laterally to reach the cortex. Only cortical regions that make contact with these microtubule bundles develop ingression.

3D Reconstruction of Microtubules in Cells Treated with a Topoisomerase II Inhibitor

In this cell treated with ICRF 187, microtubule bundles emanate from the chromosomal region and extend laterally toward the cortex, as shown after tracing and reconstructing immunostained microtubules. There is no apparent physical continuity between these "midzone" microtubules and astral or kinetochore microtubules.