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端粒花束促进裂殖酵母减数分裂前期进程及退出。

The telomere bouquet facilitates meiotic prophase progression and exit in fission yeast.

作者信息

Moiseeva Vera, Amelina Hanna, Collopy Laura C, Armstrong Christine A, Pearson Siân R, Tomita Kazunori

机构信息

Chromosome Maintenance Group, UCL Cancer Institute, University College London, London, UK.

出版信息

Cell Discov. 2017 Nov 7;3:17041. doi: 10.1038/celldisc.2017.41. eCollection 2017.

Abstract

During meiotic prophase, chromosome arrangement and oscillation promote the pairing of homologous chromosomes for meiotic recombination. This dramatic movement involves clustering of telomeres at the nuclear membrane to form the so-called telomere bouquet. In fission yeast, the telomere bouquet is formed near the spindle pole body (SPB), which is the microtubule organising centre, functionally equivalent to the metazoan centrosome. Disruption of bouquet configuration impedes homologous chromosome pairing, meiotic recombination and spindle formation. Here, we demonstrate that the bouquet is maintained throughout meiotic prophase and promotes timely prophase exit in fission yeast. Persistent DNA damages, induced during meiotic recombination, activate the Rad3 and Chk1 DNA damage checkpoint kinases and extend the bouquet stage beyond the chromosome oscillation period. The auxin-inducible degron system demonstrated that premature termination of the bouquet stage leads to severe extension of prophase and consequently spindle formation defects. However, this delayed exit from meiotic prophase was not caused by residual DNA damage. Rather, loss of chromosome contact with the SPB caused delayed accumulation of CDK1-cyclin B at the SPB, which correlated with impaired SPB separation. In the absence of the bouquet, CDK1-cyclin B localised near the telomeres but not at the SPB at the later stage of meiotic prophase. Thus, bouquet configuration is maintained throughout meiotic prophase, by which this spatial organisation may facilitate local and timely activation of CDK1 near the SPB. Our findings illustrate that chromosome contact with the nuclear membrane synchronises meiotic progression of the nucleoplasmic chromosomes with that of the cytoplasmic SPB.

摘要

在减数分裂前期,染色体的排列和振荡促进同源染色体配对以进行减数分裂重组。这种剧烈运动涉及端粒在核膜处聚集形成所谓的端粒花束。在裂殖酵母中,端粒花束在纺锤体极体(SPB)附近形成,纺锤体极体是微管组织中心,功能上等同于后生动物的中心体。花束结构的破坏会阻碍同源染色体配对、减数分裂重组和纺锤体形成。在此,我们证明花束在整个减数分裂前期都得以维持,并促进裂殖酵母中前期的适时退出。减数分裂重组过程中诱导产生的持续性DNA损伤会激活Rad3和Chk1 DNA损伤检查点激酶,并使花束阶段延长至染色体振荡期之后。生长素诱导的降解系统表明,花束阶段的过早终止会导致前期严重延长,进而导致纺锤体形成缺陷。然而,减数分裂前期的这种延迟退出并非由残留的DNA损伤引起。相反,染色体与纺锤体极体失去接触会导致CDK1 - 细胞周期蛋白B在纺锤体极体处的积累延迟,这与纺锤体极体分离受损相关。在没有花束的情况下,CDK1 - 细胞周期蛋白B在减数分裂前期后期定位于端粒附近而非纺锤体极体处。因此,花束结构在整个减数分裂前期都得以维持,通过这种空间组织可能有助于在纺锤体极体附近局部且适时地激活CDK1。我们的研究结果表明,染色体与核膜的接触使核质染色体的减数分裂进程与细胞质纺锤体极体的减数分裂进程同步。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/93c0/5674143/a2e371a00c19/celldisc201741-f1.jpg

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