title: Monopolar spindle 1 (MPS1) kinase promotes production of closed MAD2 (C-MAD2) conformer and assembly of the mitotic checkpoint complex.
abstract: MPS1 kinase is an essential component of the spindle assembly checkpoint (SAC), but its functioning mechanisms are not fully understood. We have shown recently that direct interaction between BUBR1 and MAD2 is critical for assembly and function of the human mitotic checkpoint complex (MCC), the SAC effector. Here we report that inhibition of MPS1 kinase activity by reversine disrupts BUBR1-MAD2 as well as CDC20-MAD2 interactions, causing premature activation of the anaphase-promoting complex/cyclosome. The effect of MPS1 inhibition is likely due to reduction of closed MAD2 (C-MAD2), as expressing a MAD2 mutant (MAD2(L13A)) that is locked in the C conformation rescued the checkpoint defects. In the presence of reversine, exogenous C-MAD2 does not localize to unattached kinetochores but is still incorporated into the MCC. Contrary to a previous report, we found that sustained MPS1 activity is required for maintaining both the MAD1·C-MAD2 complex and open MAD2 (O-MAD2) at unattached kinetochores to facilitate C-MAD2 production. Additionally, mitotic phosphorylation of BUBR1 is also affected by MPS1 inhibition but seems dispensable for MCC assembly. Our results support the notion that MPS1 kinase promotes C-MAD2 production and subsequent MCC assembly to activate the SAC.
authors.affiliation: From the Department of Biological Sciences, The University of Toledo, Toledo, Ohio 43606.
authors.forename: Aaron R
authors.initials: AR
authors.lastname: Tipton
authors.forename: Wenbin
authors.initials: W
authors.lastname: Ji
authors.forename: Brianne
authors.initials: B
authors.lastname: Sturt-Gillespie
authors.forename: Michael E
authors.initials: ME
authors.lastname: Bekier
authors.forename: Kexi
authors.initials: K
authors.lastname: Wang
authors.forename: William R
authors.initials: WR
authors.lastname: Taylor
authors.forename: Song-Tao
authors.initials: ST
authors.lastname: Liu
mesh_terms: D064173:Anaphase-Promoting Complex-Cyclosome / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D059447:Cell Cycle Checkpoints / Q000187:drug effects; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D018386:Kinetochores / Q000187:drug effects / Q000378:metabolism; D064246:Mad2 Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008938:Mitosis; D009025:Morpholines / Q000494:pharmacology; D046912:Multiprotein Complexes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011487:Protein Conformation; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011687:Purines / Q000494:pharmacology; D015398:Signal Transduction; D008941:Spindle Apparatus / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; C577697:MAD2L1 protein, human; D064246:Mad2 Proteins; D009025:Morpholines; D046912:Multiprotein Complexes; D011687:Purines; D064173:Anaphase-Promoting Complex-Cyclosome; D011505:Protein-Tyrosine Kinases; C584277:BUB1 protein, human; D017346:Protein Serine-Threonine Kinases; C075840:TTK protein, human; C484369:2-(4-morpholinoanilino)-6-cyclohexylaminopurine
keywords: BUBR1; Cell Cycle; E3 Ubiquitin Ligase; MAD2; MPS1 Kinase; Mitosis; Mitotic Checkpoint Complex (MCC); Protein Complexes; Protein Kinases; Spindle Assembly Checkpoint