Overview Cell Structures Cell Migration Cell Division  

Regulation of Cell Shape and Ingression by the Small GTPase Rho during Cytokinesis

O'Connell et al., J. Cell Biol. 144:305-313 (1999)

The small GTPase Rho is known to play an important role in regulating the actin cytoskeleton. It's involvement in cytokinesis has been suggested by a number of suggestive observations, including the concentration of active Rho as well as GEF and GAP in the equatorial region. To investigate the function of Rho in cytokinesis, a specific inhibitor, C3 ribosyltranferase, was microinjected into cultured Normal Rat Kidney epithelial cells.

C3 Transferase Induces Poorly Coordinated Cortical Ingression

Microinjection of C3 causes dividing NRK cells to spread in random directions. Following anaphase onset, poorly coordinated cortical ingression takes place at multiple sites. The upper cell forms multiple furrows including one along the equator. The lower cell shows extensive ectopic furrow-like activities but failure of cytokinesis. Recording time, 40 min (upper) and 32 min (lower).



C3 Transferase Induces Abnormal Movements of Membrane Components

Membrane components are labeled with fluorescent latex beads as in a previous experiment. Normally membrane-bound beads move after anaphase onset toward the equator. Microinjection of C3 causes the beads to move at prometaphase toward congregating chromosomes. During anaphase, these beads move with separated chromosomes toward the spindle poles. Recording time, 40 min.

C3 Transferase Induces Cortical Ingression Even upon the Inhibition of Mitosis

Normally cytokinesis is inhibited when mitosis is inhibited by nocodazole, which depolymerizes microtubules. Microinjection of C3 induces random cortical ingression even when mitosis and anaphase onset are inhibited by nocodazole. Recording time, 15 min.