title: Distinct organization and regulation of the outer kinetochore KMN network downstream of CENP-C and CENP-T.
abstract: The kinetochore provides a vital connection between chromosomes and spindle microtubules [1, 2]. Defining the molecular architecture of the core kinetochore components is critical for understanding the mechanisms by which the kinetochore directs chromosome segregation. The KNL1/Mis12 complex/Ndc80 complex (KMN) network acts as the primary microtubule-binding interface at kinetochores [3] and provides a platform to recruit regulatory proteins [4]. Recent work found that the inner kinetochore components CENP-C and CENP-T act in parallel to recruit the KMN network to kinetochores [5-8]. However, due to the presence of these dual pathways, it has not been possible to distinguish differences in the nature of kinetochore assembly downstream of CENP-C or CENP-T. Here, we separated these pathways by targeting CENP-C and CENP-T independently to an ectopic chromosomal locus in human cells. Our work reveals that the organization of the KMN network components downstream of CENP-C and CENP-T is distinct. CENP-C recruits the Ndc80 complex through its interactions with KNL1 and the Mis12 complex. In contrast, CENP-T directly interacts with Ndc80, which in turn promotes KNL1/Mis12 complex recruitment through a separate region on CENP-T, resulting in functional relationships for KMN network localization that are inverted relative to the CENP-C pathway. We also find that distinct regulatory paradigms control the assembly of these pathways, with Aurora B kinase promoting KMN network recruitment to CENP-C and cyclin-dependent kinase (CDK) regulating KMN network recruitment to CENP-T. This work reveals unexpected complexity for the architecture and regulation of the core components of the kinetochore-microtubule interface.
authors: Whitehead Institute for Biomedical Research and Department of Biology, MIT, Nine Cambridge Center, Cambridge, MA 02142, USA.
authors: Florencia
authors: F
authors: Rago
authors: Whitehead Institute for Biomedical Research and Department of Biology, MIT, Nine Cambridge Center, Cambridge, MA 02142, USA.
authors: Karen E
authors: KE
authors: Gascoigne
authors: Whitehead Institute for Biomedical Research and Department of Biology, MIT, Nine Cambridge Center, Cambridge, MA 02142, USA. Electronic address: icheese@wi.mit.edu.
authors: Iain M
authors: IM
authors: Cheeseman
mesh_terms: D045744:Cell Line, Tumor; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000378:metabolism*; D020090:Chromosome Segregation / Q000502:physiology*; D003598:Cytoskeletal Proteins; D005455:Fluorescent Antibody Technique; D040461:Gene Components; D006801:Humans; D018386:Kinetochores / Q000502:physiology*; D059566:M Phase Cell Cycle Checkpoints / Q000502:physiology*; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D046912:Multiprotein Complexes / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D010766:Phosphorylation
chemical_list: C534001:CENPT protein, human; D002868:Chromosomal Proteins, Non-Histone; D003598:Cytoskeletal Proteins; C472643:Knl1 protein, human; C492664:MIS12 protein, human; D008869:Microtubule-Associated Proteins; D046912:Multiprotein Complexes; C120529:NDC80 protein, human; D009687:Nuclear Proteins; C060905:centromere protein C