Moore D P, Page A W, Tang T T, Kerrebrock A W, Orr-Weaver T L
Whitehead Institute for Biomedical Research, and the Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA.
J Cell Biol. 1998 Mar 9;140(5):1003-12. doi: 10.1083/jcb.140.5.1003.
The Drosophila MEI-S332 protein has been shown to be required for the maintenance of sister-chromatid cohesion in male and female meiosis. The protein localizes to the centromeres during male meiosis when the sister chromatids are attached, and it is no longer detectable after they separate. Drosophila melanogaster male meiosis is atypical in several respects, making it important to define MEI-S332 behavior during female meiosis, which better typifies meiosis in eukaryotes. We find that MEI-S332 localizes to the centromeres of prometaphase I chromosomes in oocytes, remaining there until it is delocalized at anaphase II. By using oocytes we were able to obtain sufficient material to investigate the fate of MEI-S332 after the metaphase II-anaphase II transition. The levels of MEI-S332 protein are unchanged after the completion of meiosis, even when translation is blocked, suggesting that the protein dissociates from the centromeres but is not degraded at the onset of anaphase II. Unexpectedly, MEI-S332 is present during embryogenesis, localizes onto the centromeres of mitotic chromosomes, and is delocalized from anaphase chromosomes. Thus, MEI-S332 associates with the centromeres of both meiotic and mitotic chromosomes and dissociates from them at anaphase.
果蝇MEI-S332蛋白已被证明在雄性和雌性减数分裂中维持姐妹染色单体黏连是必需的。在雄性减数分裂中，当姐妹染色单体相连时，该蛋白定位于着丝粒，而在它们分离后则不再能检测到。黑腹果蝇的雄性减数分裂在几个方面是非典型的，因此确定MEI-S332在雌性减数分裂中的行为很重要，因为雌性减数分裂更能代表真核生物的减数分裂。我们发现MEI-S332定位于卵母细胞中期I染色体的着丝粒，一直保持在那里，直到在后期II时发生去定位。通过使用卵母细胞，我们能够获得足够的材料来研究MEI-S332在中期II-后期II转变后的命运。即使翻译被阻断，减数分裂完成后MEI-S332蛋白的水平也没有变化，这表明该蛋白在后期II开始时从着丝粒解离但没有被降解。出乎意料的是，MEI-S332在胚胎发育期间存在，定位于有丝分裂染色体的着丝粒，并从后期染色体上去定位。因此，MEI-S332与减数分裂和有丝分裂染色体的着丝粒相关联，并在后期从它们上解离下来。
