Clathrin ensures mitotic spindle stability and efficient chromosome alignment, independently of its vesicle trafficking function. Although clathrin localizes to the mitotic spindle and kinetochore fiber microtubule bundles, the mechanisms by which clathrin stabilizes microtubules are unclear. We show that clathrin adaptor interaction sites on clathrin heavy chain (CHC) are repurposed during mitosis to directly recruit the microtubule-stabilizing protein GTSE1 to the spindle. Structural analyses reveal that these sites interact directly with clathrin-box motifs on GTSE1. Disruption of this interaction releases GTSE1 from spindles, causing defects in chromosome alignment. Surprisingly, this disruption destabilizes astral microtubules, but not kinetochore-microtubule attachments, and chromosome alignment defects are due to a failure of chromosome congression independent of kinetochore–microtubule attachment stability. GTSE1 recruited to the spindle by clathrin stabilizes microtubules by inhibiting the microtubule depolymerase MCAK. This work uncovers a novel role of clathrin adaptor-type interactions to stabilize nonkinetochore fiber microtubules to support chromosome congression, defining for the first time a repurposing of this endocytic interaction mechanism during mitosis.

中文翻译：

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网格蛋白的接头相互作用位点被重新调整以稳定有丝分裂期间的微管

网格蛋白确保有丝分裂纺锤体的稳定性和有效的染色体排列，独立于其囊泡运输功能。尽管网格蛋白定位于有丝分裂纺锤体和动粒纤维微管束，但网格蛋白稳定微管的机制尚不清楚。我们发现，网格蛋白重链 (CHC) 上的网格蛋白接头相互作用位点在有丝分裂过程中被重新利用，以直接将微管稳定蛋白 GTSE1 募集至纺锤体。结构分析表明这些位点直接与 GTSE1 上的网格蛋白盒基序相互作用。这种相互作用的破坏会使 GTSE1 从纺锤体中释放出来，导致染色体排列缺陷。令人惊讶的是，这种破坏会破坏星体微管的稳定性，但不会破坏动粒-微管附着的稳定性，并且染色体排列缺陷是由于独立于动粒-微管附着稳定性的染色体会聚失败所致。GTSE1 通过网格蛋白募集至纺锤体，通过抑制微管解聚酶 MCAK 来稳定微管。这项工作揭示了网格蛋白接头型相互作用在稳定非着丝粒纤维微管以支持染色体会聚方面的新作用，首次定义了有丝分裂期间这种内吞相互作用机制的重新利用。