Lateral and End-On Kinetochore Attachments Are Coordinated to Achieve Bi-orientation in Drosophila Oocytes.
Lateral and End-On Kinetochore Attachments Are Coordinated to Achieve Bi-orientation in Drosophila Oocytes.
复制标题
横向和末端着丝点附着物协调以实现果蝇卵母细胞的双向取向。
DOI：
10.1371/journal.pgen.1005605
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发表时间：
2015-10
期刊：
影响因子：
4.5
通讯作者：
McKim KS
中科院分区：
文献类型：
--
作者：
Radford SJ;Hoang TL;Głuszek AA;Ohkura H;McKim KS
在没有中心体的卵母细胞中，染色体指导双极纺锤体的组装。染色体和微管之间的相互作用对于纺锤体的形成和染色体分离都是必不可少的，但这些相互作用的性质和功能尚不清楚。我们已经研究了缺乏两个着丝粒蛋白，NDC 80和SPC 105 R，和着丝粒相关的马达蛋白，CENP-E的卵母细胞，以表征着丝粒微管附件对纺锤体组装和染色体分离的影响在果蝇卵母细胞。我们发现，启动纺锤体组装的结果从染色体微管的相互作用是kinetochore-independent。然而，纺锤体的稳定性取决于中央纺锤体和动粒组分。这种稳定性与运动舞蹈微管附件和同源物的双向取向的变化相一致。我们提出，双向取向过程开始与着丝粒横向沿着中央纺锤体微管向其负端移动。这种运动取决于SPC 105 R，可以在没有NDC 80的情况下发生，并且被CENP-E马达的正端定向力所拮抗。依赖于NDC 80的末端着丝粒微管附件是稳定同源物的双向取向所必需的。一个令人惊讶的发现是，SPC 105 R而不是NDC 80是在减数分裂I时姐妹着丝粒共定向所必需的。总之，这些结果表明，在卵母细胞中，kinetochorse依赖性和非依赖性染色体微管附件一起工作，以促进染色体的准确分离。在无中心体卵母细胞中，纺锤体的组装依赖于染色体。卵母细胞染色体微管相互作用的性质，组织纺锤体双极性和同源物的方向一直不清楚。我们已经发现，几种类型的功能染色体微管相互作用存在于卵母细胞中，并且每种类型都参与染色体定向和纺锤体组装的独特方面。我们在这里提出了一个模型，基于染色体的纺锤体组装和卵母细胞中的染色体运动，突出了多个和不受重视的作用所发挥的动粒，并有影响同源染色体双定向减数分裂过程中。
In oocytes, where centrosomes are absent, the chromosomes direct the assembly of a bipolar spindle. Interactions between chromosomes and microtubules are essential for both spindle formation and chromosome segregation, but the nature and function of these interactions is not clear. We have examined oocytes lacking two kinetochore proteins, NDC80 and SPC105R, and a centromere-associated motor protein, CENP-E, to characterize the impact of kinetochore-microtubule attachments on spindle assembly and chromosome segregation in Drosophila oocytes. We found that the initiation of spindle assembly results from chromosome-microtubule interactions that are kinetochore-independent. Stabilization of the spindle, however, depends on both central spindle and kinetochore components. This stabilization coincides with changes in kinetochore-microtubule attachments and bi-orientation of homologs. We propose that the bi-orientation process begins with the kinetochores moving laterally along central spindle microtubules towards their minus ends. This movement depends on SPC105R, can occur in the absence of NDC80, and is antagonized by plus-end directed forces from the CENP-E motor. End-on kinetochore-microtubule attachments that depend on NDC80 are required to stabilize bi-orientation of homologs. A surprising finding was that SPC105R but not NDC80 is required for co-orientation of sister centromeres at meiosis I. Together, these results demonstrate that, in oocytes, kinetochore-dependent and -independent chromosome-microtubule attachments work together to promote the accurate segregation of chromosomes. In acentrosomal oocytes, spindle assembly depends on the chromosomes. The nature of the chromosome-microtubule interactions in oocytes that organize spindle bipolarity and orientation of the homologs has been unclear. We have found that several types of functional chromosome-microtubule interactions exist in oocytes, and that each type participates in unique aspects of chromosome orientation and spindle assembly. We present here a model for chromosome-based spindle assembly and chromosome movements in oocytes that highlights the multiple and unappreciated roles played by the kinetochores and has implications for how homologous chromosomes bi-orient during meiosis.