title: A spindle checkpoint arrest and a cytokinesis failure by the dominant-negative polo-box domain of Plk1 in U-2 OS cells.
abstract: Polo kinases play critical roles for proper M-phase progression. They are characterized by the presence of two regions of homology in the C-terminal non-catalytic domain, termed polo-box 1 (PB1) and polo-box 2 (PB2). Here we demonstrate that both PB1 and PB2 are required for targeting the catalytic activity of Plk1 to centrosomes, midbody, and kinetochores. Expression of either kinase-inactive PLK1/K82M or the C-terminal plk1 Delta N induced a pre-anaphase arrest with elevated Cdc2 and Plk1 activity. Prophase-arrested cells exhibited randomly oriented spindle structures, whereas metaphase cells exhibited aberrant bipolar spindles with Mad2 localization at kinetochores of misaligned chromosomes. Microtubule nucleation activity of centrosomes was not compromised. In vivo time-lapse studies revealed that expression of plk1 Delta N resulted in repeated cycles of bipolar spindle formation and disruption, suggestive of a defect in spindle stability. A prolonged arrest frequently led to the generation of micronucleated cells in the absence of sisterchromatid separation and centrosome duplication, indicating that micronucleation is not a result of accumulated cytokinesis failures. Interestingly, bypass of the mitotic arrest by dominant-negative spindle checkpoint components led to a failure in completion of cytokinesis. We propose that, in mammalian cells, the polo-box-dependent Plk1 activity is required for proper metaphase/anaphase transition and for cytokinesis.
authors.affiliation: Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892-4258, USA.
authors.forename: Yeon-Sun
authors.initials: YS
authors.lastname: Seong
authors.forename: Keiju
authors.initials: K
authors.lastname: Kamijo
authors.forename: Jae-Seon
authors.initials: JS
authors.lastname: Lee
authors.forename: Ester
authors.initials: E
authors.lastname: Fernandez
authors.forename: Ryoko
authors.initials: R
authors.lastname: Kuriyama
authors.forename: Toru
authors.initials: T
authors.lastname: Miki
authors.forename: Kyung S
authors.initials: KS
authors.lastname: Lee
mesh_terms: D000705:Anaphase; D001859:Bone Neoplasms / Q000235:genetics; D002453:Cell Cycle / Q000235:genetics / Q000502:physiology*; D018797:Cell Cycle Proteins; D002455:Cell Division; D002869:Chromosome Aberrations; D006801:Humans; D008938:Mitosis; D012516:Osteosarcoma / Q000235:genetics; D011418:Prophase; D011494:Protein Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D008941:Spindle Apparatus / Q000502:physiology*; D014407:Tumor Cells, Cultured; D000097869:Polo-Like Kinase 1
chemical_list: D018797:Cell Cycle Proteins; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D000097869:Polo-Like Kinase 1