The CENP-A NAC/CAD kinetochore complex controls chromosome congression and spindle bipolarity.
Kinetochores are complex protein machines that link chromosomes to spindle microtubules and contain a structural core composed of two conserved protein-protein interaction networks: the well-characterized KMN (KNL1/MIND/NDC80) and the recently identified CENP-A NAC/CAD. Here we show that the CENP-A NAC/CAD subunits can be assigned to one of two different functional classes; depletion of Class I proteins (Mcm21R(CENP-O) and Fta1R(CENP-L)) causes a failure in bipolar spindle assembly. In contrast, depletion of Class II proteins (CENP-H, Chl4R(CENP-N), CENP-I and Sim4R(CENP-K)) prevents binding of Class I proteins and causes chromosome congression defects, but does not perturb spindle formation. Co-depletion of Class I and Class II proteins restores spindle bipolarity, suggesting that Class I proteins regulate or counteract the function of Class II proteins. We also demonstrate that CENP-A NAC/CAD and KMN regulate kinetochore-microtubule attachments independently, even though CENP-A NAC/CAD can modulate NDC80 levels at kinetochores. Based on our results, we propose that the cooperative action of CENP-A NAC/CAD subunits and the KMN network drives efficient chromosome segregation and bipolar spindle assembly during mitosis.
McClelland
Sarah E
SE
Chromosome Segregation Laboratory, Marie Curie Research Institute, The Chart, Oxted, Surrey, UK.
Borusu
Satyarebala
S
Amaro
Ana C
AC
Winter
Jennifer R
JR
Belwal
Mukta
M
McAinsh
Andrew D
AD
Meraldi
Patrick
P
D000818:Animals; D001324:Autoantigens / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002453:Cell Cycle / Q000502:physiology; D016764:Cell Polarity; D000076247:Centromere Protein A; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002875:Chromosomes / Q000378:metabolism*; D003598:Cytoskeletal Proteins; D006367:HeLa Cells; D006801:Humans; D018386:Kinetochores / Q000378:metabolism*; D046911:Macromolecular Substances / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D008941:Spindle Apparatus / Q000378:metabolism*
D001324:Autoantigens; C000619700:CENPA protein, human; D000076247:Centromere Protein A; D002868:Chromosomal Proteins, Non-Histone; D003598:Cytoskeletal Proteins; D046911:Macromolecular Substances; C120529:NDC80 protein, human; D009687:Nuclear Proteins; D021122:Protein Subunits; D034741:RNA, Small Interfering