Condensins I and II are essential for construction of bivalent chromosomes in mouse oocytes.
Condensins I and II are essential for construction of bivalent chromosomes in mouse oocytes.
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DOI：
10.1091/mbc.e11-05-0423
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发表时间：
2011-09
影响因子：
3.3
通讯作者：
Hirano T
中科院分区：
文献类型：
--
作者：
Lee J;Ogushi S;Saitou M;Hirano T
在小鼠卵母细胞中，凝聚素I定位在着丝粒区域周围，而凝聚素II集中在Meta-I二价染色体的染色单体轴上。这两种凝聚素都是减数分裂染色体动力学的许多方面所必需的，包括个体化、分解和分离，以及姐妹动粒的单极附着。在许多真核生物中，凝聚素I和II在有丝分裂过程中以有序的方式与染色体结合，并在其组装和分离中发挥非重叠的功能。在这里，我们首次报告的时空动态和功能的两个凝聚素复合物在小鼠卵母细胞减数分裂。在萌发囊泡阶段（前期I），凝聚素I存在于细胞质中，而凝聚素II位于细胞核内。在萌发囊泡破裂后，凝聚素II开始与染色体结合，并在中期I集中在二价染色体的染色单体轴上。REC 8沿着染色体臂的长度沿着“粘合”染色体臂。与凝聚素II形成鲜明对比的是，凝聚素I在中期I主要定位于着丝粒区域周围，并且仅在后期I之后才开始稳定地与染色体臂结合。抗体注射实验表明，凝聚素功能所需的减数分裂染色体动力学的许多方面，包括染色体的个性化，分辨率和分离。我们建议，这两个凝聚素复合物在构建二价染色体中发挥独特的作用：凝聚素II可能在解决姐妹染色单体轴中发挥主要作用，而凝聚素I可能有助于姐妹着丝粒的单极附着，可能通过组装一个独特的着丝粒结构下面。
In mouse oocytes, condensin I localizes around centromeric regions, whereas condensin II is concentrated onto chromatid axes of Meta-I bivalent chromosomes. Both condensins are required for many aspects of meiotic chromosome dynamics, including individualization, resolution, and segregation, as well as monopolar attachment of sister kinetochores. In many eukaryotes, condensins I and II associate with chromosomes in an ordered fashion during mitosis and play nonoverlapping functions in their assembly and segregation. Here we report for the first time the spatiotemporal dynamics and functions of the two condensin complexes during meiotic divisions in mouse oocytes. At the germinal vesicle stage (prophase I), condensin I is present in the cytoplasm, whereas condensin II is localized within the nucleus. After germinal vesicle breakdown, condensin II starts to associate with chromosomes and becomes concentrated onto chromatid axes of bivalent chromosomes by metaphase I. REC8 “glues” chromosome arms along their lengths. In striking contrast to condensin II, condensin I localizes primarily around centromeric regions at metaphase I and starts to associate stably with chromosome arms only after anaphase I. Antibody injection experiments show that condensin functions are required for many aspects of meiotic chromosome dynamics, including chromosome individualization, resolution, and segregation. We propose that the two condensin complexes play distinctive roles in constructing bivalent chromosomes: condensin II might play a primary role in resolving sister chromatid axes, whereas condensin I might contribute to monopolar attachment of sister kinetochores, possibly by assembling a unique centromeric structure underneath.