title: Cell cycle-dependent translocation of PRC1 on the spindle by Kif4 is essential for midzone formation and cytokinesis.
abstract: The spindle midzone, a conspicuous network of antiparallel interdigitating nonkinetochore microtubules between separating chromosomes, plays a crucial role in regulating the initiation and completion of cytokinesis. In this study, we report the use of time-lapse microscopy and a human kinesin endoribonucleases RNase III-prepared short interfering RNA (esiRNA) library to identify Kif4 as a motor protein that translocates PRC1, a spindle midzone-associated cyclin-dependent kinase substrate protein, to the plus ends of interdigitating spindle microtubules during the metaphase-to-anaphase transition. We show that Kif4 binds to PRC1 through its "stalk plus tail" domains and Kif4 and PRC1 colocalize on the spindle midzone/midbody during anaphase and cytokinesis. Suppression of Kif4 expression by Kif4 esiRNA results in the inhibition of PRC1 translocation, a block of the midzone formation, and a failure of cytokinesis. PRC1 translocation and midzone formation can be restored, and the cytokinetic defects can be rescued in Kif4 esiRNA-treated cells by coexpression of Kif4 but not its motor dead mutant Kif4md. Furthermore, we show that cyclin-dependent kinase phosphorylation of PRC1 controls the timing of PRC1 translocation by Kif4. These results, in light of the crucial role of PRC1 in midzone formation, indicate that cell cycle-dependent translocation of PRC1 by Kif4 is essential for midzone formation and cytokinesis.
authors.affiliation: Programs of Cancer Genetics and Epigenetics and Signal Transduction, The Burnham Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA.
authors.forename: Changjun
authors.initials: C
authors.lastname: Zhu
authors.forename: Wei
authors.initials: W
authors.lastname: Jiang
mesh_terms: D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000378:metabolism*; D018844:Cyclin-Dependent Kinases / Q000502:physiology; D048749:Cytokinesis; D006367:HeLa Cells; D006801:Humans; D016547:Kinesins / Q000502:physiology*; D008938:Mitosis; D010766:Phosphorylation; D021381:Protein Transport; D008941:Spindle Apparatus / Q000378:metabolism*
chemical_list: D018797:Cell Cycle Proteins; C116662:PRC1 protein, human; D018844:Cyclin-Dependent Kinases; C484228:KIF4A protein, human; C484229:KIF4B protein, human; D016547:Kinesins