Mps1 kinase activity restrains anaphase during an unperturbed mitosis and targets Mad2 to kinetochores.
Mps1 is an upstream component of the spindle assembly checkpoint, which, in human cells, is required for checkpoint activation in response to spindle damage but not apparently during an unperturbed mitosis. Mps1 also recruits Mad1 and Mad2 to kinetochores. However, whether the enzymatic activity of Mps1 is required for these processes is unclear. To address this question, we established an RNA interference (RNAi) complementation assay. Repression of Mps1 triggers premature anaphase, often with unaligned or maloriented chromosomes. This phenotype is rescued by an RNAi-resistant wild-type Mps1 transgene but not by a catalytically inactive mutant. An analogue-sensitive allele, Mps1(M602A), also rescues the RNAi-induced defect, but not when inhibited by the adenosine triphosphate analogue 1-NM-PP1. Thus, Mps1 activity does restrain anaphase during an unperturbed mitosis. Furthermore, although catalytically inactive Mps1 can restore kinetochore localization of Mad1, only the active kinase restores Mad2 localization. Thus, in human cells, Mps1 catalytic activity is required for spindle checkpoint function and recruitment of Mad2.
Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, England, UK.
Anthony
A
Tighe
Oliver
O
Staples
Stephen
S
Taylor
D000705:Anaphase / Q000187:drug effects; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D018386:Kinetochores / Q000187:drug effects / Q000201:enzymology*; D064246:Mad2 Proteins; D009687:Nuclear Proteins / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D021381:Protein Transport / Q000187:drug effects; D011505:Protein-Tyrosine Kinases; D034741:RNA, Small Interfering / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism*; D008941:Spindle Apparatus / Q000187:drug effects / Q000201:enzymology
D002135:Calcium-Binding Proteins; D018797:Cell Cycle Proteins; C501384:MAD1L1 protein, human; C577697:MAD2L1 protein, human; D064246:Mad2 Proteins; D009687:Nuclear Proteins; D047428:Protein Kinase Inhibitors; D034741:RNA, Small Interfering; D012097:Repressor Proteins; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; C075840:TTK protein, human