title: The chromokinesin Kid is required for maintenance of proper metaphase spindle size.
abstract: The human chromokinesin Kid/kinesin-10, a plus end-directed microtubule (MT)-based motor with both microtubule- and DNA-binding domains, is required for proper chromosome alignment at the metaphase plate. Here, we performed RNA interference experiments to deplete endogenous Kid from HeLa cells and confirmed defects in metaphase chromosome arm alignment in Kid-depleted cells. In addition, we noted a shortening of the spindle length, resulting in a pole-to-pole distance only 80% of wild type. The spindle microtubule-bundles with which Kid normally colocalize became less robust. Rescue of the two Kid deficiency phenotypes-imprecise chromosome alignment at metaphase and shortened spindles- exhibited distinct requirements. Mutants lacking either the DNA-binding domain or the MT motor ATPase failed to rescue the former defect, whereas rescue of the shortened spindle phenotype required neither activity. Kid also exhibits microtubule bundling activity in vitro, and rescue of the shortened spindle phenotype and the bundling activity displayed similar domain requirements, except that rescue required a coiled-coil domain not needed for bundling. These results suggest that distinct from its role in chromosome movement, Kid contributes to spindle morphogenesis by mediating spindle microtubules stabilization.
authors.affiliation: Division of Oncology, Department of Cancer Biology, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan.
authors.forename: Noriko
authors.initials: N
authors.lastname: Tokai-Nishizumi
authors.forename: Miho
authors.initials: M
authors.lastname: Ohsugi
authors.forename: Emiko
authors.initials: E
authors.lastname: Suzuki
authors.forename: Tadashi
authors.initials: T
authors.lastname: Yamamoto
mesh_terms: D002467:Cell Nucleus / Q000648:ultrastructure; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D066298:In Vitro Techniques; D016547:Kinesins / Q000235:genetics / Q000502:physiology*; D008677:Metaphase; D008870:Microtubules / Q000378:metabolism; D008954:Models, Biological; D034622:RNA Interference; D008941:Spindle Apparatus / Q000378:metabolism* / Q000648:ultrastructure; D014162:Transfection
chemical_list: D004268:DNA-Binding Proteins; C098764:KIF22 protein, human; D016547:Kinesins