Lin Chiou-Hong, Hu Chi-Kuo, Shih Hsiu-Ming
Graduate Institute of Life Sciences, National Defense Medical Center, Taipei 11529, Taiwan.
J Cell Biol. 2010 Jun 28;189(7):1097-105. doi: 10.1083/jcb.200911120. Epub 2010 Jun 21.
Mitotic spindles play essential roles in chromosome congression and segregation during mitosis. Aurora A regulates spindle assembly in part via phosphorylating human TACC3 on S558, which triggers TACC3 relocalization to mitotic spindles and stabilizes microtubules (MTs). In this study, we identified clathrin heavy chain (CHC) as an adaptor protein to recruit S558-phosphorylated TACC3 onto the spindle during mitosis for MT stabilization. CHC binds phospho-S558 TACC3 via its linker domain and first CHC repeat. CHC depletion or mutation on phospho-TACC3 binding abrogates TACC3 spindle relocalization. Depletion of either or both CHC and TACC3 yields similar defective phenotypes: loss of ch-TOG on spindles, disorganized spindles, and chromosome misalignment with comparable mitotic delay. Our findings elucidate the association between aurora A phosphorylation and spindle apparatus and demonstrate that regulation from aurora A is mediated by CHC in recruiting phospho-TACC3 and subsequently ch-TOG to mitotic spindles.
有丝分裂纺锤体在有丝分裂期间的染色体汇聚和分离过程中发挥着至关重要的作用。极光激酶A（Aurora A）部分通过磷酸化人TACC3蛋白的第558位丝氨酸来调节纺锤体组装，这会促使TACC3重新定位到有丝分裂纺锤体上并稳定微管（MTs）。在本研究中，我们鉴定出网格蛋白重链（CHC）作为一种衔接蛋白，在有丝分裂期间将磷酸化第558位丝氨酸的TACC3募集到纺锤体上以稳定微管。CHC通过其连接结构域和第一个CHC重复序列与磷酸化第558位丝氨酸的TACC3结合。CHC的缺失或磷酸化TACC3结合位点的突变会消除TACC3在纺锤体上的重新定位。CHC和TACC3其中之一或两者都缺失会产生相似的缺陷表型：纺锤体上缺少ch-TOG、纺锤体紊乱以及染色体排列错误并伴有相当程度的有丝分裂延迟。我们的研究结果阐明了极光激酶A磷酸化与纺锤体装置之间的关联，并表明极光激酶A的调控是由CHC介导的，它招募磷酸化TACC3以及随后的ch-TOG到有丝分裂纺锤体上。
