title: Molecular interactions of Polo-like-kinase 1 with the mitotic kinesin-like protein CHO1/MKLP-1.
abstract: Polo-like kinases and kinesin-like motor proteins are among the many proteins implicated in the execution of cytokinesis. Polo-like-kinase 1 (Plk1) interacts with the mitotic kinesin-like motor protein CHO1/MKLP-1 during anaphase and telophase, and CHO1/MKLP-1 is a Plk1 substrate in vitro. Here, we explore the molecular interactions of these two key contributors to mitosis and cytokinesis. Using the transient transfection approach, we show that the C-terminus of Plk1 binds CHO1/MKLP-1 in a Polo-box-dependent manner and that the stalk domain of CHO1/MKLP-1 is responsible for its binding to Plk1. The stalk domain was found to localize with Plk1 to the mid-body, and Plk1 appears to be mislocalized in CHO1/MKLP-1-depleted cells during late mitosis. We showed that Ser904 and Ser905 are two major Plk1 phosphorylation sites. Using the vector-based RNA interference approach, we showed that depletion of CHO1/MKLP-1 causes the formation of multinucleate cells with more centrosomes, probably because of a defect in the early phase of cytokinesis. Overexpression of a non-Plk1-phosphorylatable CHO1 mutant caused cytokinesis defects, presumably because of dominant negative effect of the construct. Finally, CHO1-depletion-induced multinucleation could be partially rescued by co-transfection of a non-degradable hamster wild-type CHO1 construct, but not an unphosphorylatable mutant. These data provide more detailed information about the interaction between Plk1 and CHO1/MKLP-1, and the significance of this is discussed.
authors.affiliation: Department of Molecular and Cellular Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA. liu13@fas.harvard.edu
authors.forename: Xiaoqi
authors.initials: X
authors.lastname: Liu
authors.forename: Tianhua
authors.initials: T
authors.lastname: Zhou
authors.forename: Ryoko
authors.initials: R
authors.lastname: Kuriyama
authors.forename: Raymond L
authors.initials: RL
authors.lastname: Erikson
mesh_terms: D000818:Animals; D001665:Binding Sites; D015153:Blotting, Western; D016466:CHO Cells; D019556:COS Cells; D018797:Cell Cycle Proteins; D002467:Cell Nucleus / Q000378:metabolism / Q000648:ultrastructure; D006224:Cricetinae; D048749:Cytokinesis; D004247:DNA / Q000378:metabolism; D016193:G1 Phase; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D008856:Microscopy, Fluorescence; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008938:Mitosis; D008957:Models, Genetic; D009154:Mutation; D010766:Phosphorylation; D011485:Protein Binding; D011494:Protein Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins; D012313:RNA / Q000737:chemistry; D034622:RNA Interference; D012694:Serine / Q000737:chemistry; D013692:Telophase; D013997:Time Factors; D014162:Transfection; D000097869:Polo-Like Kinase 1
chemical_list: D018797:Cell Cycle Proteins; D004247:DNA; D049452:Green Fluorescent Proteins; D008869:Microtubule-Associated Proteins; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D012313:RNA; D012694:Serine; D000097869:Polo-Like Kinase 1; C092935:KIF23 protein, human