Human Mps1 protein kinase is required for centrosome duplication and normal mitotic progression

Abstract

The mitotic spindle is essential for the maintenance of genetic stability, and in budding yeast its assembly and function depend on the Mps1 protein kinase. Mps1p is required for centrosome duplication and the spindle checkpoint. Several recent reports demonstrate that vertebrate Mps1 proteins regulate the spindle checkpoint, but reports conflict regarding their role in centrosome duplication. Here we provide multiple lines of evidence that the human Mps1 protein (hMps1) is required for centrosome duplication. A recently described rabbit polyclonal antibody against hMps1 specifically recognizes centrosomes in a variety of human cell types. Overexpression of a dominant-negative version of hMps1 (hMps1KD) can prevent centrosome duplication in a variety of cell types, and active hMps1 accelerates centrosome reduplication in U2OS cells. Finally, we demonstrate that disruption of hMps1 function with pools of hMps1-specific small interfering RNAs causes a pleiotropic phenotype resulting from the combination of severe mitotic abnormalities and failures in centrosome duplication. This approach demonstrates that hMps1 is required for centrosome duplication and for the normal progression of mitosis, and suggests that the threshold level of hMps1 function required for centrosome duplication is lower than that required for hMps1 mitotic functions.

The cell cycle checkpoint kinase CHK2 mediates DNA damage-induced stabilization of TTK/hMps1

“…Consistent with the previous report (Fisk et al, 2003), knockdown of TTK severely hampered cell survival as revealed by the numbers of colonies formed after 2 weeks of culture (Figure 6e). This defect was rescued by reexpression of WT but not T288A TTK in the Tet-off cells (Figure 6e), suggesting that the CHK2-TTK feedback control and TTK Thr288 phosphorylation are important for cell survival.…”

“…As TTK/hMps1 was shown to be required for proper mitotic progression (Fisk et al, 2003), whether the feedback regulation would affect long term cell survival was assessed by clonogenic assay. Consistent with the previous report (Fisk et al, 2003), knockdown of TTK severely hampered cell survival as revealed by the numbers of colonies formed after 2 weeks of culture (Figure 6e).…”

“…The Mps1 family of kinases has been described in several other species including mouse (esk/mMps1; Douville et al, 1992), S. cerevisiae (Mps1p; Winey et al, 1991), S. pombe (Mph1p; He et al, 1998), Xenopus laevis (xMps1; Abrieu et al, 2001), zebrafish (mps1/ncp; Poss et al, 2002) and Drosophila (Mps1; Fischer et al, 2004). In budding yeast (S. cerevisiae), this kinase is required for spindle pole duplication and spindle assembly checkpoint, whereas in mammals, although involved in spindle checkpoint, the kinase is thought to be involved in centrosome duplication, although this is debated (Weiss and Winey, 1996;Fisk and Winey, 2001; Stucke et al, 2002;Fisk et al, 2003). During mitosis, Mps1 localizes to kinetochores and is required for proper chromosome alignment and segregation as well as the recruitment of other mitotic checkpoint proteins in the event of unattached chromosome or uneven tension at the kinetochores (Abrieu et al, 2001;Stucke et al, 2004;Vigneron et al, 2004;Jelluma et al, 2008).…”

TTK kinase is essential for the centrosomal localization of TACC2

“…In addition, our ultrastructural studies revealed the localization of TTK to corona fibers of the kinetochore in prometaphase cells but relocated to centrosome upon the chromosomal alignment at the equator [4]. Dynamic localization of TTK supports the notion in which TTK participates in centrosome-based spindle checkpoint (e.g., [4,5]). …”

SAC‐ing mitotic errors: How the spindle assembly checkpoint (SAC) plays defense against chromosome mis‐segregation

“…It remains unclear whether the SAC component, Mps1p, also plays a role in centrosome duplication in higher eukaryotes [Fischer et al, 2004;Fisk et al, 2003;Liu et al, 2003;Stucke et al, 2004;Stucke et al, 2002] as it does in budding [Winey et al, 1991] but not in fission yeast [He et al, 1998]. The mammalian Ndc80p complex [McCleland et al, 2003], the ROD and ZW10 kinetochore proteins [Basto et al, 2000;Chan et al, 2000], the outer kinetochore protein Zwint-1 [Obuse et al, 2004;Wang et al, 2004a], and the kinetochore-associated NEK2A protein [Lou et al, 2004] are also required for the spindle checkpoint, indicating that the kinetochore's role in SAC signaling is evolutionarily conserved, although no ROD, ZW10, or Zwint-1 homologues have been identified in yeast.…”