RAMA1 is a novel kinetochore protein involved in kinetochore-microtubule attachment
RAMA1 is a novel kinetochore protein involved in kinetochore-microtubule attachment
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DOI：
10.1242/jcs.051912
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发表时间：
2009-07-15
影响因子：
4
通讯作者：
Medema, Rene H.
中科院分区：
文献类型：
--
作者：
Raaijmakers, Jonne A.;Tanenbaum, Marvin E.;Medema, Rene H.
在有丝分裂过程中，动粒需要附着在从纺锤体极发出的微管上。几种蛋白质复合物已被证明介导的kinetochore-microtubule相互作用。然而，随着越来越多的新发现的动粒蛋白，目前还不清楚是否所有的主要成分的动粒微管接口已被确定。因此，我们进行了高通量的RNAi筛选，以确定其他因素参与kinetochore-microtubule附着，并确定RAMA 1作为这一过程的一种新的调节剂。RAMA 1的缺失导致严重的染色体排列缺陷和检查点依赖性有丝分裂停滞。我们表明，这是由于减少kinetochore-microtubule附件。RAMA 1在有丝分裂的所有阶段定位于纺锤体和外部动粒，并通过核心动粒-微管附着因子Hec 1被招募到动粒。有趣的是，与Hec 1不同，RAMA 1与动粒的关联是高度动态的，这表明它不是动粒的结构组成部分。与此一致，所有其他测试的动粒蛋白不需要RAMA 1用于其动粒定位。两者合计，这些结果确定RAMA 1作为一种新的动粒蛋白，并建议RAMA 1可能有一个直接的作用，在介导的动粒微管相互作用。
During mitosis, kinetochores need to attach to microtubules emanating from spindle poles. Several protein complexes have been shown to mediate the kinetochore-microtubule interaction. However, with the continually growing number of newly identified kinetochore proteins, it is unclear whether all major components of the kinetochore-microtubule interface have been identified. We therefore performed a high-throughput RNAi screen to identify additional factors involved in kinetochore-microtubule attachment, and identified RAMA1 as a novel regulator of this process. Depletion of RAMA1 results in severe chromosome alignment defects and a checkpoint-dependent mitotic arrest. We show that this is due to reduced kinetochore-microtubule attachments. RAMA1 localizes to the spindle and to outer kinetochores throughout all phases of mitosis and is recruited to kinetochores by the core kinetochore-microtubule attachment factor Hec1. Interestingly, unlike Hec1, the association of RAMA1 with kinetochores is highly dynamic, suggesting that it is not a structural component of the kinetochore. Consistent with this, all other kinetochore proteins tested do not require RAMA1 for their kinetochore localization. Taken together, these results identify RAMA1 as a novel kinetochore protein and suggest that RAMA1 may have a direct role in mediating kinetochore-microtubule interactions.