Dynamics and Functional Roles of Aurora B Kinase during Cytokinesis

Mol. Biol. Cell 13:1099-1108 (2002)

Curr. Biol. 12:894-899 (2002)

Aurora B kinase is known to be an important signaling component for cytokinesis. Upon anaphase onset, it's localization shows an intriguing transition from centromeres on chromosomes to midzone microtubules where it is believed to stimulate cytokinesis. This dynamic process may be studied using Normal Rat Kidney cells expressing GFP-tagged aurora B. In addition, the functional role of aurora B kinase activity may be analyzed by expressing a GFP-tagged mutant with a dominant negative defect in the kinase domain.

Dynamics of Aurora B during Cell Division

Aurora B is localized at centromeres from prophase through early anaphase. It then relocates to midzone microtubules and condenses into short segments crossing the equatorial plane. These segments then coalesces laterally to form the midbody. Recording time, 26.5 min.

Aurora B as a Centromere Marker for Observing Chromosomal Congression

Before anaphase onset, the localization of aurora B at centromeres allows it to serve as a marker for tracking chromosomal congression. Recording time, 49 min.

Dissociation of Aurora B from the Midbody Following Cytokinesis

After cytokinesis, aurora B dissociates from the midbody as discrete segments that move along microtubules. Recording time, 105 min.

Dependence of the Dissociation of Aurora B from Centromeres on CDK1 Deactivation

CDK1 deactivation is inhibited by expressing the non-degradable Delta90 cyclin B. Persistent CDK1 activities inhibit midzone assembly and cytokinesis without affecting chromosomal congregation or anaphase onset, as shown in a separate study. Aurora B in these cells remains associated with centromeres after chromosome separation. Recording time, 37 min.

Dynamics of Kinase-Inactive Aurora B in a Cell that Entered Anaphase

Expression of kinase-inactive aurora B has strong dominant negative effects. While many cells exit prometaphase abnormally, a fraction manage to enter anaphase. In these cells, kinase-inactive aurora B shows the initial transition from centromeres to midzone microtubules after anaphase onset. However the localization along microtubules is unstable, as if the mutant protein were falling off the ends of microtubules. Cytokinesis is also inhibited. Recording time, 23 min.

Defects of Chromosomal Congression in a Cell Expressing Kinase-Inactive Aurora B

In many cells expressing kinase-inactive aurora B, chromosome movements are defective and chromosomes fail to congress into a metaphase plate. They instead form two elongated clusters parallel to the spindle axis. In this cell the spindle poles are visible as two dots along the central horizontal line. Recording time, 77 min.