The Human Kinesin Kif18A Is a Motile Microtubule Depolymerase Essential for Chromosome Congression

Chemical Genetics, Independent Research Group, Department of Cell Biology, Max-Planck-Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany.
Current Biology (Impact Factor: 9.92). 04/2007; 17(6):488-98. DOI: 10.1016/j.cub.2007.02.036
Source: PubMed

ABSTRACT The accurate alignment of chromosomes at the spindle equator is fundamental for the equal distribution of the genome in mitosis and thus for the genetic integrity of eukaryotes. Although it is well established that chromosome movements are coupled to microtubule dynamics, the underlying mechanism is not well understood.
By combining RNAi-depletion experiments with in vitro biochemical assays, we demonstrate that the human kinesin Kif18A is a motile microtubule depolymerase essential for chromosome congression in mammalian tissue culture cells. We show that in vitro Kif18A is a slow plus-end-directed kinesin that possesses microtubule depolymerizing activity. Notably, Kif18A like its yeast ortholog Kip3p depolymerizes longer microtubules more quickly than shorter ones. In vivo, Kif18A accumulates in mitosis where it localizes close to the plus ends of kinetochore microtubules. The depletion of Kif18A induces aberrantly long mitotic spindles and loss of tension across sister kinetochores, resulting in the activation of the Mad2-dependent spindle-assembly checkpoint. Live-cell microscopy studies revealed that in Kif18A-depleted cells, chromosomes move at reduced speed and completely fail to align at the spindle equator.
These studies identify Kif18A as a dual-functional kinesin and a key component of chromosome congression in mammalian cells.

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    • "Both of these genes belong to recently described CINSARC (complexity index in sarcomas) gene expression signature that predicts metastatic outcome in translocation and non-translocation related sarcomas, and in gastrointestinal stromal tumors (GIST) (Chibon et al., 2010; Lagarde et al., 2012, 2013). KIF18A (mapped to chromosome 11p14) encodes kinesin family member 18A, a microtubule-depolymerizing protein, which is a key component of chromosome congression and cell division (Mayr et al., 2007; Zhang et al., 2010). It was demonstrated that over-expression of KIF18A in breast cancer cells results in multinucleation , whereas the suppression of KIF18A expression causes inhibition of cancer cell growth both in vitro and in vivo (Zhang et al., 2010). "
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