The spindle function of CDCA4
The spindle function of CDCA4
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CDCA4的纺锤体功能
DOI：
10.1002/cm.20286
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发表时间：
2008-07-01
影响因子：
--
通讯作者：
Zeng, Changqing
中科院分区：
文献类型：
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作者：
Wang, Limin;Zhu, Guixin;Zeng, Changqing
为了发现像 NuMA 一样在间期核和有丝分裂纺锤体中发挥作用的新型蛋白质，我们使用汇集的自身免疫抗体进行了 cDNA 文库筛选。在阳性克隆中，我们发现了最近鉴定的转录调节蛋白（CDCA4），其具有独特的核有丝分裂装置分布。 CDCA4 定位于中期纺锤体极和后期的中区。此外，在一半中期细胞中观察到与纺锤体平行的密集CDCA4积累，但在后期细胞中没有观察到，这意味着CDCA4从后期与中区结合的瞬时形式。有丝分裂停滞将CDCA4从中心体中溶解，但在纺锤体恢复过程中，CDCA4总是与微管成核灶共定位，作为微管组织中心的组成部分。 CDCA4 的 RNA 干扰导致多核和多极纺锤体显着增加，表明染色体分离或胞质分裂的功能受损。然而，纺锤体检查点和中心体周期似乎不受这种干扰的影响。此外，CDCA4 缺失导致细胞增殖加速，这可能是由于 CDCA4 作为转录抑制因子的核功能被破坏。尽管 GFP-CDCA4 在核质中表达，但免疫荧光显示间期 CDCA4 位于核仁中。通过序列比对和截短突变体的表达鉴定，N 末端 KRKC 结构域似乎是核定位信号。综上所述，我们的结果表明，作为一种新型核有丝分裂装置蛋白，CDCA4 参与前期的纺锤体组织。当后期开始时，CDCA4 可能作为参与染色体分离或胞质分裂的中区因子发挥不同的作用。
In an attempt to discover novel proteins functioning in both interphase nucleus and mitotic spindle as NuMA does, we carried out cDNA library screening with pooled autoimmune antibodies. Among positive clones we found a recently identified transcription regulatory protein (CDCA4) with the distinctive nuclear-mitotic apparatus distribution. CDCA4 localizes at metaphase spindle poles and the midzone in later stages. Additionally, an intensive CDCA4 accumulation parallel to spindle was observed in half of metaphase cells but not in later stages, implying a transient form of CDCA4 binding to midzone from anaphase. Mitotic arrest dissolved CDCA4 from centrosomes but during the spindle recovery, CDCA4 invariably colocalized with the microtubule nucleation foci as a component of microtubule organization center. RNA interference of CDCA4 resulted in significant increase of multinuclei and multipolar spindles, suggesting impaired function in chromosome segregation or cytokinesis. However, the spindle checkpoint and the centrosome cycle appeared not to be affected by such interference. Furthermore, CDCA4 depletion resulted in accelerated cell proliferation, perhaps due to the disruption of CDCA4 nuclear function as a transcription suppressor. Interphase CDCA4 is localized in nucleoli by immunofluorescence, although GFP-CDCA4 expressed in the nucleoplasm. An N-terminal KRKC domain appears to be the nuclear localization signal as identified by sequence alignment and the expression of truncated mutants. Taken together, our results suggested that as a novel nuclear-mitotic apparatus protein, CDCA4 is involved in spindle organization from prometaphase. When anaphase begins, CDCA4 may play a different role as a midzone factor involved in chromosome segregation or cytokinesis.