Cohesin Rec8 is required for reductional chromosome segregation at meiosis
Cohesin Rec8 is required for reductional chromosome segregation at meiosis
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作者：
Watanabe, Y;Nurse, P
当细胞从有丝分裂中退出时，它们的姐妹染色单体失去凝聚力并分离到分裂细胞的相反两极，导致染色体均等分离。相比之下，减数分裂第一阶段（减数分裂I）的还原分离要求姐妹染色单体通过它们的着丝粒保持联合，并一起移动到同一极。随着细胞退出减数分裂II，着丝粒凝聚力丧失，然后姐妹染色单体可以分离（1-4）。裂殖酵母粘附蛋白Reed对减数分裂是特异性的并且是减数分裂所需的（5-8）。在这里，我们表明，Rec 8出现在着丝粒和相邻的染色体臂在减数分裂前的S期。着丝粒红在减数分裂I中持续存在，在减数分裂II后期消失。当rec 8基因被删除时，姐妹染色单体在减数分裂I时分离，导致相等的而不是减数分裂的染色体分离。我们建议，在减数分裂I期间，在着丝粒Rec 8的持久性保持姐妹染色单体的凝聚力，它的存在在着丝粒相邻区域定向的动粒，使姐妹染色单体移动到同一极。这导致了染色体分离的还原模式，这是将二倍体合子还原为单倍体配子所必需的。
When cells exit from mitotic cell division, their sister chromatids lose cohesion and separate to opposite poles of the dividing cell, resulting in equational chromosome segregation. In contrast, the reductional segregation of the first stage of meiotic cell division (meiosis I) requires that sister chromatids remain associated through their centromeres and move together to the same pole. Centromeric cohesion is lost as cells exit from meiosis II and sister chromatids can then separate(1-4). The fission yeast cohesin protein Reed is specific to and required for meiosis(5-8). Here we show that Rec8 appears in the centromeres and adjacent chromosome arms during the pre-meiotic S phase. Centromeric Red persists throughout meiosis I and disappears at anaphase of meiosis II. When the rec8 gene is deleted, sister chromatids separate at meiosis I, resulting in equational rather than reductional chromosome segregation. We propose that the persistence of Rec8 at centromeres during meiosis I maintains sister-chromatid cohesion, and that its presence in the centromere-adjacent regions orients the kinetochores so that sister chromatids move to the same pole. This results in the reductional pattern of chromosome segregation necessary to reduce a diploid zygote to haploid gametes.