Human Mps1 kinase is required for the spindle assembly checkpoint but not for centrosome duplication

Max-Planck Institute for Biochemistry, Department of Cell Biology, Am Klopferspitz 18a, D-82152 Martinsried, Germany.
The EMBO Journal (Impact Factor: 10.43). 05/2002; 21(7):1723-32. DOI: 10.1093/emboj/21.7.1723
Source: PubMed


Budding yeast Mps1p kinase has been implicated in both the duplication of microtubule-organizing centers and the spindle assembly checkpoint. Here we show that hMps1, the human homolog of yeast Mps1p, is a cell cycle-regulated kinase with maximal activity during M phase. hMps1 localizes to kinetochores and its activity and phosphorylation state increase upon activation of the mitotic checkpoint. By antibody microinjection and siRNA, we demonstrate that hMps1 is required for human cells to undergo checkpoint arrest in response to microtubule depolymerization. In contrast, centrosome (re-)duplication as well as cell division occur in the absence of hMps1. We conclude that hMps1 is required for the spindle assembly checkpoint but not for centrosome duplication.

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Available from: Lionel Arnaud, Oct 03, 2015
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    • "The human Mps1 protein (also known as TTK) displays maximum expression and kinase activity in mitosis and exhibits dynamic subcellular localization throughout mitosis [9]–[10]. In the absence of Mps1, the SAC is compromised [9], [11]. It is likely that Mps1 executes its function by recruiting Mad1 and Mad2 to unattached kinetochores. "
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    ABSTRACT: The spindle assembly checkpoint (SAC) is a surveillance mechanism monitoring cell cycle progression, thus ensuring accurate chromosome segregation. The conserved mitotic kinase Mps1 is a key component of the SAC. The human Mps1 exhibits comprehensive phosphorylation during mitosis. However, the related biological relevance is largely unknown. Here, we demonstrate that 8 autophosphorylation sites within the N-terminus of Mps1, outside of the catalytic domain, are involved in regulating Mps1 kinetochore localization. The phospho-mimicking mutant of the 8 autophosphorylation sites impairs Mps1 localization to kinetochore and also affects the kinetochore recruitment of BubR1 and Mad2, two key SAC effectors, subsequently leading to chromosome segregation errors. Interestingly, the non-phosphorylatable mutant of the 8 autophosphorylation sites enhances Mps1 kinetochore localization and delays anaphase onset. We further show that the Mps1 phospho-mimicking and non-phosphorylatable mutants do not affect metaphase chromosome congression. Thus, our results highlight the importance of dynamic autophosphorylation of Mps1 in regulating accurate chromosome segregation and ensuring proper mitotic progression.
    PLoS ONE 09/2014; 9(9):e104723. DOI:10.1371/journal.pone.0104723 · 3.23 Impact Factor
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    • "By contrast, condensin II is predominantly localized in the nucleus. Given that Mps1 is localized in the nucleus and in the cytoplasm (Stucke et al., 2002; Nihira et al., 2008), we examined the subcellular localization of the association between Mps1 and SMC2. Subcellular fractionation and immunoprecipitation with anti-SMC2 demonstrated that nuclear, but not cytoplasmic, SMC2 specifically interacts with Mps1 (Fig. 1 E and Fig. S1 A). "
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    ABSTRACT: During mitosis, genomic DNA is condensed into chromosomes to promote its equal segregation into daughter cells. Chromosome condensation occurs during cell cycle progression from G2 phase to mitosis. Failure of chromosome compaction at prophase leads to subsequent misregulation of chromosomes. However, the molecular mechanism that controls the early phase of mitotic chromosome condensation is largely unknown. Here, we show that Mps1 regulates initial chromosome condensation during mitosis. We identify condensin II as a novel Mps1-associated protein. Mps1 phosphorylates one of the condensin II subunits, CAP-H2, at Ser492 during mitosis, and this phosphorylation event is required for the proper loading of condensin II on chromatin. Depletion of Mps1 inhibits chromosomal targeting of condensin II and accurate chromosome condensation during prophase. These findings demonstrate that Mps1 governs chromosomal organization during the early stage of mitosis to facilitate proper chromosome segregation.
    The Journal of Cell Biology 06/2014; 205(6). DOI:10.1083/jcb.201308172 · 9.83 Impact Factor
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    • "Consequently, loss of MPS1 activity results in failure to delay mitosis when unattached kinetochores persist, in a dramatic shortening of mitosis and in anaphases with severe chromosome missegregations that can culminate in chromosomal translocations (Jelluma et al., 2008b; Tighe et al., 2008; Maciejowski et al., 2010; Sliedrecht et al., 2010; Janssen et al., 2011). Localization of MPS1 to unattached kinetochores at the onset of mitosis depends on the outer kinetochore proteins HEC1 and NUF2 (Martin-Lluesma et al., 2002; Stucke et al., 2002; Meraldi et al., 2004) and is regulated by the Aurora B kinase (Santaguida et al., 2011; Saurin et al., 2011). These proteins operate in one pathway, as the ability of centromeretethered Aurora B to recruit MPS1 in G2-phase cells depends on HEC1 (Saurin et al., 2011). "
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    ABSTRACT: The mitotic checkpoint ensures correct chromosome segregation by delaying cell cycle progression until all kinetochores have attached to the mitotic spindle. In this paper, we show that the mitotic checkpoint kinase MPS1 contains an N-terminal localization module, organized in an N-terminal extension (NTE) and a tetratricopeptide repeat (TPR) domain, for which we have determined the crystal structure. Although the module was necessary for kinetochore localization of MPS1 and essential for the mitotic checkpoint, the predominant kinetochore binding activity resided within the NTE. MPS1 localization further required HEC1 and Aurora B activity. We show that MPS1 localization to kinetochores depended on the calponin homology domain of HEC1 but not on Aurora B-dependent phosphorylation of the HEC1 tail. Rather, the TPR domain was the critical mediator of Aurora B control over MPS1 localization, as its deletion rendered MPS1 localization insensitive to Aurora B inhibition. These data are consistent with a model in which Aurora B activity relieves a TPR-dependent inhibitory constraint on MPS1 localization.
    The Journal of Cell Biology 04/2013; 201(2). DOI:10.1083/jcb.201210033 · 9.83 Impact Factor
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