title: Aurora A phosphorylates MCAK to control ran-dependent spindle bipolarity.
abstract: During mitosis, mitotic centromere-associated kinesin (MCAK) localizes to chromatin/kinetochores, a cytoplasmic pool, and spindle poles. Its localization and activity in the chromatin region are regulated by Aurora B kinase; however, how the cytoplasmic- and pole-localized MCAK are regulated is currently not clear. In this study, we used Xenopus egg extracts to form spindles in the absence of chromatin and centrosomes and found that MCAK localization and activity are tightly regulated by Aurora A. This regulation is important to focus microtubules at aster centers and to facilitate the transition from asters to bipolar spindles. In particular, we found that MCAK colocalized with NuMA and XMAP215 at the center of Ran asters where its activity is regulated by Aurora A-dependent phosphorylation of S196, which contributes to proper pole focusing. In addition, we found that MCAK localization at spindle poles was regulated through another Aurora A phosphorylation site (S719), which positively enhances bipolar spindle formation. This is the first study that clearly defines a role for MCAK at the spindle poles as well as identifies another key Aurora A substrate that contributes to spindle bipolarity.
authors.affiliation: Departments of Biochemistry and Molecular Biology, and Medical Sciences, Indiana University, Bloomington, IN 47405, USA.
authors.forename: Xin
authors.initials: X
authors.lastname: Zhang
authors.forename: Stephanie C
authors.initials: SC
authors.lastname: Ems-McClung
authors.forename: Claire E
authors.initials: CE
authors.lastname: Walczak
mesh_terms: D000818:Animals; D064127:Aurora Kinases; D001665:Binding Sites; D018385:Centrosome / Q000737:chemistry; D002843:Chromatin / Q000737:chemistry / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D016547:Kinesins / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D008869:Microtubule-Associated Proteins / Q000737:chemistry; D008954:Models, Biological; D009154:Mutation; D009687:Nuclear Proteins / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D008941:Spindle Apparatus; D029867:Xenopus Proteins / Q000737:chemistry / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: C486738:CKAP5 protein, Xenopus; D002843:Chromatin; D008869:Microtubule-Associated Proteins; C489079:NUMA1 protein, Xenopus; D009687:Nuclear Proteins; D029867:Xenopus Proteins; C509242:mitotic centromere-associated kinesin, Xenopus; D064127:Aurora Kinases; D017346:Protein Serine-Threonine Kinases; D016547:Kinesins