title: A TACC3/ch-TOG/clathrin complex stabilises kinetochore fibres by inter-microtubule bridging.
abstract: Kinetochore fibres (K-fibres) of the spindle apparatus move chromosomes during mitosis. These fibres are discrete bundles of parallel microtubules (MTs) that are crosslinked by inter-MT 'bridges' that are thought to improve fibre stability during chromosomal movement. The identity of these bridges is unknown. Clathrin is a multimeric protein that has been shown to stabilise K-fibres during early mitosis by a mechanism independent of its role in membrane trafficking. In this study, we show that clathrin at the mitotic spindle is in a transforming acidic colied-coil protein 3 (TACC3)/colonic, hepatic tumour overexpressed gene (ch-TOG)/clathrin complex. The complex is anchored to the spindle by TACC3 and ch-TOG. Ultrastructural analysis of clathrin-depleted K-fibres revealed a selective loss of a population of short inter-MT bridges and a general loss of MTs. A similar loss of short inter-MT bridges was observed in TACC3-depleted K-fibres. Finally, immunogold labelling confirmed that inter-MT bridges in K-fibres contain clathrin. Our results suggest that the TACC3/ch-TOG/clathrin complex is an inter-MT bridge that stabilises K-fibres by physical crosslinking and by reducing rates of MT catastrophe.
authors.affiliation: Physiological Laboratory, University of Liverpool, Liverpool, UK.
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Booth
authors.forename: Fiona E
authors.initials: FE
authors.lastname: Hood
authors.forename: Ian A
authors.initials: IA
authors.lastname: Prior
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Royle
mesh_terms: D064127:Aurora Kinases; D002966:Clathrin / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D015151:Immunoblotting; D018386:Kinetochores / Q000502:physiology*; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000235:genetics / Q000378:metabolism*; D008938:Mitosis; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D008941:Spindle Apparatus / Q000235:genetics / Q000378:metabolism*
chemical_list: C454180:CKAP5 protein, human; D002966:Clathrin; D008869:Microtubule-Associated Proteins; D012333:RNA, Messenger; C120551:TACC3 protein, human; D064127:Aurora Kinases; D017346:Protein Serine-Threonine Kinases