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J Cell Biol September 14, 2015; 210 (6): 899-916.

Kinetochore function is controlled by a phospho-dependent coexpansion of inner and outer components.

Wynne DJ , Funabiki H .

It is widely accepted that the kinetochore is built on CENP-A-marked centromeric chromatin in a hierarchical order from inner to outer kinetochore. Recruitment of many kinetochore proteins depends on microtubule attachment status, but it remains unclear how their assembly/disassembly is orchestrated. Applying 3D structured illumination microscopy to Xenopus laevis egg extracts, here we reveal that in the absence of microtubule attachment, proteins responsible for lateral attachment and spindle checkpoint signaling expand to form micrometer-scale fibrous structures over CENP-A-free chromatin, whereas a core module responsible for end-on attachment (CENP-A, CENP-T, and Ndc80) does not. Both outer kinetochore proteins (Bub1, BubR1, Mad1, and CENP-E) and the inner kinetochore component CENP-C are integral components of the expandable module, whose assembly depends on multiple mitotic kinases (Aurora B, Mps1, and Plx1) and is suppressed by protein phosphatase 1. We propose that phospho-dependent coexpansion of CENP-C and outer kinetochore proteins promotes checkpoint signal amplification and lateral attachment, whereas their selective disassembly enables the transition to end-on attachment.

PubMed ID: 26347137
PMC ID: PMC4576862
Article link: J Cell Biol
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: aurkb bub1 bub1b cenpa cenpc cenpe cenpt ddx59 gnl3 mxd1 ndc80 plk1 rpe rps27

Article Images: [+] show captions
References [+] :
Abrieu, Mps1 is a kinetochore-associated kinase essential for the vertebrate mitotic checkpoint. 2001, Pubmed, Xenbase