title: Self-assembly and sorting of acentrosomal microtubules by TACC3 facilitate kinetochore capture during the mitotic spindle assembly.
abstract: Kinetochore capture by dynamic kinetochore microtubule fibers (K fibers) is essential for proper chromosome alignment and accurate distribution of the replicated genome during cell division. Although this capture process has been extensively studied, the mechanisms underlying the initiation of this process and the proper formation of the K fibers remain largely unknown. Here we show that transforming acidic coiled-coil-containing protein 3 (TACC3) is essential for kinetochore capture and proper K-fiber formation in HeLa cells. To observe the assembly of acentrosomal microtubules more clearly, the cells were released from higher concentrations of nocodazole into zero or lower concentrations. We find that small acentrosomal TACC3-microtubule aster formation near the kinetochores and binding of the asters with the kinetochores are the initial steps of the kinetochore capture by the acentrosomal microtubules, and that the sorting of kinetochore-captured acentrosomal microtubules with centrosomal microtubules leads to the capture of kinetochore by centrosomal microtubules from both spindle poles. We demonstrate that the sorting of the TACC3-associated microtubules with the centrosomal microtubules is a crucial process for spindle assembly and chromosome movement. These findings, which are also supported in the unperturbed mitosis without nocodazole, reveal a critical TACC3-dependent acentrosomal microtubule nucleation and sorting process to regulate kinetochore-microtubule connections and provide deep insight into the mechanisms of mitotic spindle assembly and chromosome alignment.
authors.affiliation: Ministry of Education Key Laboratory of Cell Proliferation and Differentiation and State Key Laboratory of Biomembrane and Membrane Biotechnology, College of Life Sciences, Peking University, Beijing 100871, China.
authors.forename: Wenxiang
authors.initials: W
authors.lastname: Fu
authors.forename: Hao
authors.initials: H
authors.lastname: Chen
authors.forename: Gang
authors.initials: G
authors.lastname: Wang
authors.forename: Jia
authors.initials: J
authors.lastname: Luo
authors.forename: Zhaoxuan
authors.initials: Z
authors.lastname: Deng
authors.forename: Guangwei
authors.initials: G
authors.lastname: Xin
authors.forename: Nan
authors.initials: N
authors.lastname: Xu
authors.forename: Xiao
authors.initials: X
authors.lastname: Guo
authors.forename: Jun
authors.initials: J
authors.lastname: Lei
authors.forename: Qing
authors.initials: Q
authors.lastname: Jiang
authors.forename: Chuanmao
authors.initials: C
authors.lastname: Zhang
mesh_terms: D015153:Blotting, Western; D005455:Fluorescent Antibody Technique; D006367:HeLa Cells; D006801:Humans; D018386:Kinetochores / Q000378:metabolism*; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism*; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D008941:Spindle Apparatus / Q000378:metabolism / Q000502:physiology*
chemical_list: D008869:Microtubule-Associated Proteins; D034741:RNA, Small Interfering; C120551:TACC3 protein, human
keywords: cell cycle; centrosome; noncentrosomal