The kinesin-like protein CENP-E is kinetochore-associated throughout poleward chromosome segregation during anaphase-A

Abstract

The kinesin-like protein CENP-E transiently associates with kinetochores following nuclear envelope breakdown in late prophase, remains bound throughout metaphase, but sometime after anaphase onset it releases and by telophase becomes bound to interzonal microtubules of the mitotic spindle. Inhibition of poleward chromosome movement in vitro by CENP-E antibodies and association of CENP-E with minus-end directed microtubule motility in vitro have combined to suggest a key role for CENP-E as an anaphase chromosome motor. For this to be plausible in vivo depends on whether CENP-E remains kinetochore associated during anaphase. Using Indian muntjac cells whose seven chromosomes have large, easily tracked kinetochores, we now show that CENP-E is kinetochore-associated throughout the entirety of anaphase-A (poleward chromosome movement), relocating gradually during spindle elongation (anaphase-B) to the interzonal microtubules. These observations support roles for CENP-E not only in the initial alignment of chromosomes at metaphase and in spindle elongation in anaphase-B, but also in poleward chromosome movement in anaphase-A.