title: Sumoylation of Kif18A plays a role in regulating mitotic progression.
abstract: BACKGROUND
  Kif18A, the kinesin-8 motor protein, plays an essential role in regulating alignment of bi-oriented chromosomes at the midzone during mitosis. Kinesin proteins, including Kif18A, are often deregulated in many types of cancers and are thought to play a critical role in cancer progression. However, little is known about the post-translational modifications of Kif18A and their effects on its biological activity.
  
  
  METHODS
  Kif18A was identified to be a SUMO2 acceptor by using Ni-IDA resin to precipitate proteins from cells stably expressing His6-SUMO2. To identify the potential lysine residues, multi-site directed mutagenesis together with transient transfection and Ni-IDA pull-down assay were carried out. The confocal time-lapse imaging and immunofluorescent staining were used to study the roles of SUMO2 modification on Kif18A's activity during the cell cycle.
  
  
  RESULTS
  Kif18A is covalently modified by SUMO2 during the cell cycle, and its sumoylation peaks at metaphase and then rapidly decreases upon anaphase onset. Mutational analysis identifies multiple lysine residues (K148, K442, K533, K660 and K683) as potential SUMO acceptors. The functional studies reveal that sumoylation of Kif18A has little effect on protein stability and subcellular localization. However, compared with the wild-type control, ectopic expression of SUMO-resistant mutants of Kif18A results in a significant delay of mitotic exit. Confocal microscopy shows that cells expressing SUMO-resistant Kif18A display a compromised dissociation of BubR1 from kinetochores after anaphase onset.
  
  
  CONCLUSIONS
  Our studies reveal that sumoylation functions as an unidentified form of post-translational modification that regulates Kif18A activity during mitotic progression.
authors.affiliation: Department of Environmental Medicine, New York University Langone Medical Center, 57 Old Forge Road, Tuxedo Park, NY, 10987, USA. yfk_10987@yahoo.com.
authors.forename: Feikun
authors.initials: F
authors.lastname: Yang
authors.affiliation: Center for Drug Discovery, Northeastern University, 360 Huntington Avenue, Boston, MA, 02115, USA. yan.chen21@yahoo.com.
authors.forename: Yan
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Department of Environmental Medicine, New York University Langone Medical Center, 57 Old Forge Road, Tuxedo Park, NY, 10987, USA. wei.dai@nyumc.org.|Department of Biochemistry and Molecular Pharmacology, New York University Langone Medical Center, 57 Old Forge Road, Tuxedo Park, NY, 10987, USA. wei.dai@nyumc.org.
authors.forename: Wei
authors.initials: W
authors.lastname: Dai
mesh_terms: D000705:Anaphase / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic; D006367:HeLa Cells; D006801:Humans; D016547:Kinesins / Q000378:metabolism*; D018386:Kinetochores / Q000378:metabolism; D008938:Mitosis / Q000235:genetics*; D011499:Protein Processing, Post-Translational; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D025841:Small Ubiquitin-Related Modifier Proteins / Q000235:genetics / Q000378:metabolism*; D058207:Sumoylation / Q000235:genetics*
chemical_list: C117909:SUMO2 protein, human; D025841:Small Ubiquitin-Related Modifier Proteins; C584277:BUB1 protein, human; D017346:Protein Serine-Threonine Kinases; C502735:KIF18A protein, human; D016547:Kinesins