Two fission yeast homologs of Drosophila Mei-S332 are required for chromosome segregation during meiosis I and II
Two fission yeast homologs of Drosophila Mei-S332 are required for chromosome segregation during meiosis I and II
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DOI：
10.1016/j.cub.2004.01.051
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发表时间：
2004-02-17
期刊：
影响因子：
9.2
通讯作者：
Nasmyth, K
中科院分区：
文献类型：
--
作者：
Rabitsch, KP;Gregan, J;Nasmyth, K
背景：减数分裂从二倍体祖细胞产生单倍体配子。这种数量减半是通过一轮DNA复制后的两次连续核分裂实现的。在第一次分裂过程中，正确的染色体分离依赖于姐妹动粒朝向同一纺锤体极，而同源动粒必须朝向相反的极。第二次分裂过程中的分离依赖于着丝粒之间姐妹染色单体 cohesion（ cohesion可译为“黏连”“结合力”等，此处结合上下文暂不翻译）的保持，直到后期II开始，在黑腹果蝇中这依赖于一种称为Mei - S332的结合到着丝粒的蛋白质。
结果：我们报道了通过基因敲除筛选在裂殖酵母中鉴定出Mei - S332的两个同源物。它们与果蝇的直系同源物一起定义了一个从真菌到哺乳动物都保守的蛋白质家族。所鉴定的两个基因，sgo1和sgo2，分别是减数分裂各次分裂之间姐妹着丝粒黏连的保持以及减数分裂I期间动粒定向所必需的。在减数分裂I之后，着丝粒处保留的减数分裂黏连蛋白Rec8亚基的量在Δsgo1细胞中减少，但在Δsgo2细胞中没有减少，并且Sgo1似乎调节分离酶对Rec8的切割。Sgo1和Sgo2两种蛋白质都定位到着丝粒区域。Sgo1蛋白质的丰度在第一次减数分裂之后通常会下降，但是通过改变其3'UTR序列来延长其表达并不会对减数分裂II产生很大影响。因此，它仅仅在细胞内存在可能不足以保护着丝粒的黏连。
结论：已经鉴定出一个基于MeiS332的保守蛋白质家族。裂殖酵母的这两个同源物与减数分裂I动粒定向以及直到减数分裂II的着丝粒姐妹染色单体黏连的保持有关。
Background: Meiosis produces haploid gametes from diploid progenitor cells. This reduction is achieved by two successive nuclear divisions after one round of DNA replication. Correct chromosome segregation during the first division depends on sister kinetochores being oriented toward the same spindle pole while homologous kinetochores must face opposite poles. Segregation during the second division depends on retention of sister chromatid cohesion between centromeres until the onset of anaphase II, which in Drosophila melanogaster depends on a protein called Mei-S332 that binds to centromeres.Results: We report the identification of two homologs of Mei-S332 in fission yeast using a knockout screen. Together with their fly ortholog they define a protein family conserved from fungi to mammals. The two identified genes, sgo1 and sgo2, are required for retention of sister centromere cohesion between meiotic divisions and kinetochore orientation during meiosis 1, respectively. The amount of meiotic cohesin's Rec8 subunit retained at centromeres after meiosis I is reduced in Deltasgo1, but not in Deltasgo2, cells, and Sgo1 appears to regulate cleavage of Rec8 by separase. Both Sgo1 and Sgo2 proteins localize to centromere regions. The abundance of Sgo1 protein normally declines after the first meiotic division, but extending its expression by altering its 3'UTR sequences does not greatly affect meiosis II. Its mere presence within the cell might therefore be insufficient to protect centromeric cohesion.Conclusions: A conserved protein family based on MeiS332 has been identified. The two fission yeast homologs are implicated in meiosis I kinetochore orientation and retention of centromeric sister chromatid cohesion until meiosis II.