Mitotic Regulator SKAP Forms a Link between Kinetochore Core Complex KMN and Dynamic Spindle Microtubules

• Published in: The Journal of biological chemistry 2012-11, Vol.287 (47), p.39380-39390
• Main Authors: Wang, Xiwei, Zhuang, Xiaoxuan, Cao, Dan, Chu, Youjun, Yao, Phil, Liu, Wei, Liu, Lifang, Adams, Gregory, Fang, Guowei, Dou, Zhen, Ding, Xia, Huang, Yuejia, Wang, Dongmei, Yao, Xuebiao
• Format: Article
• Language: English
• Subjects: Cell Biology; Cell Cycle Proteins - genetics; Cell Cycle Proteins - metabolism; Chromosomal Proteins, Non-Histone - genetics; Chromosomal Proteins, Non-Histone - metabolism; Chromosome Oscillation; Chromosomes; EB1; HeLa Cells; Humans; Kinetochore; Kinetochores - metabolism; Microtubule Plus-end; Microtubule-Associated Proteins - genetics; Microtubule-Associated Proteins - metabolism; Microtubules; Microtubules - genetics; Microtubules - metabolism; Mis13; Mitosis; Mitosis - physiology; Molecular Dynamics; Multiprotein Complexes - genetics; Multiprotein Complexes - metabolism; SKAP; Spindle Apparatus - genetics; Spindle Apparatus - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M112.406652

Chromosome segregation in mitosis is orchestrated by the dynamic interactions between the kinetochore and spindle microtubules. Our recent study shows that mitotic motor CENP-E cooperates with SKAP to orchestrate an accurate chromosome movement in mitosis. However, it remains elusive how kinetochore core microtubule binding activity KMN (KNL1-MIS12-NDC80) regulates microtubule plus-end dynamics. Here, we identify a novel interaction between MIS13 and SKAP that orchestrates accurate interaction between kinetochore and dynamic spindle microtubules. SKAP physically interacts with MIS13 and specifies kinetochore localization of SKAP. Suppression of MIS13 by small interfering RNA abrogates the kinetochore localization of SKAP. Total internal reflection fluorescence microscopic assays demonstrate that SKAP exhibits an EB1-dependent, microtubule plus-end loading and tracking in vitro. Importantly, SKAP is essential for kinetochore oscillations and dynamics of microtubule plus-ends during live cell mitosis. Based on those findings, we reason that SKAP constitutes a dynamic link between spindle microtubule plus-ends and mitotic chromosomes to achieve faithful cell division. Background: KMN (KNL/MIS12/NDC80) is a kinetochore constituent essential for chromosome movements in mitosis. Results: KMN protein specifies the kinetochore localization of SKAP. SKAP regulates spindle microtubule dynamics for accurate chromosome movements. Conclusion: The MIS13-SKAP interaction links kinetochore structural components to dynamic microtubule plus-ends. Significance: MIS13-SKAP interaction governs chromosome dynamics and stability in mitosis.