Xorbit/CLASP links dynamic microtubules to chromosomes in the Xenopus meiotic spindle.
Xorbit/CLASP links dynamic microtubules to chromosomes in the Xenopus meiotic spindle.
复制标题
Xorbit/clasp将动态微管连接到爪蟾减少纺锤体中的染色体。
DOI：
10.1083/jcb.200508180
复制
发表时间：
2006-01-02
影响因子：
7.8
通讯作者：
Heald, Rebecca
中科院分区：
文献类型：
--
作者：
Hannak, Eva;Heald, Rebecca
微管（MT）结合蛋白家族，Orbit/multiple asters/细胞质连接蛋白相关蛋白，在有丝分裂过程中起着重要作用，但其功能机制尚不清楚。在这项研究中，我们使用减数分裂卵提取物来深入了解非洲爪蟾同源物Xorbit在纺锤体组装和功能中的作用。Xorbit免疫缺失或其被显性阴性片段抑制导致染色体排列缺陷和MT结构异常，包括单极和小纺锤体。xorbit缺失的提取物不能在染色质包覆珠周围成核，这表明在没有着丝体和着丝点的情况下，它对纺锤体组装是必不可少的。Xorbit稳定MT的效果在后期最为明显，此时纺锤体MT在Xorbit抑制下迅速解聚。cooh末端Xorbit片段与着丝酶相关的着丝蛋白E之间的生化相互作用可能有助于Xorbit在染色体聚集中的作用。我们提出Xorbit将动态MT +末端系在着丝点和染色质上，为纺锤体组装和染色体分离提供了至关重要的稳定活性。
A family of microtubule (MT)-binding proteins, Orbit/multiple asters/cytoplasmic linker protein–associated protein, has emerged as an important player during mitosis, but their functional mechanisms are poorly understood. In this study, we used meiotic egg extracts to gain insight into the role of the Xenopus laevis homologue Xorbit in spindle assembly and function. Xorbit immunodepletion or its inhibition by a dominant-negative fragment resulted in chromosome alignment defects and aberrant MT structures, including monopolar and small spindles. Xorbit-depleted extracts failed to nucleate MTs around chromatin-coated beads, indicating its essential requirement for spindle assembly in the absence of centrosomes and kinetochores. Xorbit's MT stabilizing effect was most apparent during anaphase, when spindle MTs depolymerized rapidly upon Xorbit inhibition. Biochemical interaction between a COOH-terminal Xorbit fragment and the kinetochore-associated kinesin centromeric protein E may contribute to Xorbit's role in chromosome congression. We propose that Xorbit tethers dynamic MT plus ends to kinetochores and chromatin, providing a stabilizing activity that is crucial for spindle assembly and chromosome segregation.