title: Functional importance of the anaphase-promoting complex-Cdh1-mediated degradation of TMAP/CKAP2 in regulation of spindle function and cytokinesis.
abstract: Cytoskeleton-associated protein 2 (CKAP2), also known as tumor-associated microtubule-associated protein (TMAP), is a novel microtubule-associated protein that is frequently upregulated in various malignances. However, its cellular functions remain unknown. A previous study has shown that its protein level begins to increase during G(1)/S and peaks at G(2)/M, after which it decreases abruptly. Ectopic overexpression of TMAP/CKAP2 induced microtubule bundling related to increased microtubule stability. TMAP/CKAP2 overexpression also resulted in cell cycle arrest during mitosis due to a defect in centrosome separation and subsequent formation of a monopolar spindle. We also show that degradation of TMAP/CKAP2 during mitotic exit is mediated by the anaphase-promoting complex bound to Cdh1 and that the KEN box motif near the N terminus is necessary for its destruction. Compared to the wild type, expression of a nondegradable mutant of TMAP/CKAP2 significantly increased the occurrence of spindle defects and cytokinesis failure. These results suggest that TMAP/CKAP2 plays a role in the assembly and maintenance of mitotic spindles, presumably by regulating microtubule dynamics, and its destruction during mitotic exit serves an important role in the completion of cytokinesis and in the maintenance of spindle bipolarity in the next mitosis.
authors.affiliation: Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, 300 Chunchundong, Jangangu, Suwon, Republic of Korea 440-746.
authors.forename: Kyung Uk
authors.initials: KU
authors.lastname: Hong
authors.forename: Young Soo
authors.initials: YS
authors.lastname: Park
authors.forename: Yeon-Sun
authors.initials: YS
authors.lastname: Seong
authors.forename: Dongmin
authors.initials: D
authors.lastname: Kang
authors.forename: Chang-Dae
authors.initials: CD
authors.lastname: Bae
authors.forename: Joobae
authors.initials: J
authors.lastname: Park
mesh_terms: D000595:Amino Acid Sequence; D064173:Anaphase-Promoting Complex-Cyclosome; D000818:Animals; D002460:Cell Line; D018385:Centrosome / Q000378:metabolism; D048749:Cytokinesis / Q000502:physiology*; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008870:Microtubules / Q000378:metabolism; D008969:Molecular Sequence Data; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D008941:Spindle Apparatus / Q000378:metabolism*; D025801:Ubiquitin / Q000378:metabolism; D043743:Ubiquitin-Protein Ligase Complexes / Q000235:genetics / Q000378:metabolism*
chemical_list: C114988:CKAP2 protein, human; D003598:Cytoskeletal Proteins; D011993:Recombinant Fusion Proteins; D025801:Ubiquitin; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome; D046988:Proteasome Endopeptidase Complex