| Title | The microtubule-associated protein EML3 regulates mitotic spindle assembly by recruiting the Augmin complex to spindle microtubules |
| Authors | Luo, Jia Yang, Biying Xin, Guangwei Sun, Mengjie Zhang, Boyan Guo, Xiao Jiang, Qing Zhang, Chuanmao |
| Affiliation | Peking Univ, Key Lab Cell Proliferat & Differentiat, Minist Educ, Beijing 100871, Peoples R China Peking Univ, State Key Lab Membrane Biol, Coll Life Sci, Beijing 100871, Peoples R China |
| Keywords | mitotic spindle microtubule microtubule-associated protein (MAP) checkpoint control mitosis cell division cytoskeleton Augmin chromosome congression EML3 microtubule nucleation spindle assembly |
| Issue Date | 2019 |
| Publisher | JOURNAL OF BIOLOGICAL CHEMISTRY |
| Abstract | In all eukaryotes, a functional mitotic spindle is essential for distributing duplicated chromosomes into daughter cells. Mitotic spindle assembly involves highly ordered arrangement of microtubules (MTs). The Augmin protein complex recruits -tubulin ring complex (-TuRC) to MTs and thereby promotes MT-based MT nucleation and mitotic spindle assembly. However, several factors that may promote Augmin recruitment to MTs remain unknown. Here, we show that echinoderm microtubule-associated protein-like 3 (EML3), an MT-associated protein, facilitates binding between MTs and Augmin/-TuRC and recruiting the latter to MTs for proper mitotic spindle assembly and kinetochore-MT connections. Using immunofluorescence microscopy, live-cell imaging, and immunoprecipitation assays, we found that EML3 recruits Augmin/-TuRC to the MTs to enhance MT-based MT nucleation in both spindle and small acentrosomal asters. We also noted that the EML3-mediated recruitment is controlled by cyclin-dependent kinase 1 (CDK1), which phosphorylated EML3 at Thr-881 and promoted its binding to Augmin/-TuRC. RNAi-mediated EML3 knockdown in HeLa cells reduced spindle localization of Augmin/-TuRC, which resulted in abnormal spindle assembly and caused kinetochore-MT misconnection. The introduction of exogenous WT or a Thr-881 phosphorylation mimic EML3 variant into the EML3 knockdown cells restored normal Augmin/-TuRC localization and spindle assembly. The EML3 knockdown also affected the spindle assembly checkpoint, delaying chromosome congression and cell division. Taken together, our results indicate that EML3 regulates mitotic spindle assembly and the kinetochore-MT connection by regulating MT-based MT nucleation and recruiting Augmin/-TuRC to MTs. |
| URI | http://hdl.handle.net/20.500.11897/549192 |
| DOI | 10.1074/jbc.RA118.007164 |
| Indexed | SCI(E) EI |
| Appears in Collections: | 细胞增殖分化调控机理研究教育部重点实验室 生命科学学院 膜生物学国家重点实验室 |
