生物谷報(bào)道：本周Nature揭示了減數(shù)分裂中的一個(gè)關(guān)鍵環(huán)節(jié)的機(jī)理,，減數(shù)分裂指的是將生殖細(xì)胞中的染色體數(shù)量從雙倍體減少為單倍體的細(xì)胞分裂過程，涉及一個(gè)DNA復(fù)制周期和兩次細(xì)胞分裂,。在第二次細(xì)胞分裂過程（減數(shù)分裂-II）中,，姐妹染色單體分離,，每個(gè)子細(xì)胞將每個(gè)染色體各接受一份，形成一個(gè)單倍體合子,。在減數(shù)分裂-I中,，姐妹染色單體需要一起連接在它們的端粒上，但保護(hù)這種端粒連接,、使其不致分離的因素卻難以確定?，F(xiàn)在，Kitajima等人發(fā)現(xiàn)了一種蛋白,。名為Shugoshin,，它在裂殖酵母的減數(shù)分裂-I期間保護(hù)端粒連接。具有類似序列的蛋白也存在于果蠅和哺乳動(dòng)物中,，說明該蛋白被廣泛保留了下來,，一種“有絲分裂”版本存在于酵母中。人類的Shugoshin類蛋白最近被發(fā)現(xiàn)是一種抗原,，在多數(shù)乳腺癌患者中該蛋白水平升高,，說明它可能是有絲分裂染色體分離所需的一種致癌蛋白。
The conserved kinetochore protein shugoshin protects centromeric cohesion during meiosis
Nature 427, 510 - 517 (05 February 2004）
Meiosis comprises a pair of specialized nuclear divisions that produce haploid germ cells. To accomplish this, sister chromatids must segregate together during the first meiotic division (meiosis I), which requires that sister chromatid cohesion persists at centromeres. The factors that protect centromeric cohesion during meiosis I have remained elusive. Here we identify Sgo1 (shugoshin), a protector of the centromeric cohesin Rec8 in fission yeast. We also identify a homologue of Sgo1 in budding yeast. We provide evidence that shugoshin is widely conserved among eukaryotes. Moreover, we identify Sgo2, a paralogue of shugoshin in fission yeast, which is required for faithful mitotic chromosome segregation. Localization of Sgo1 and Sgo2 at centromeres requires the kinase Bub1, identifying shugoshin as a crucial target for the kinetochore function of Bub1. These findings provide insights into the evolution of meiosis and kinetochore regulation during mitosis and meiosis.
