Maternal MEMI Promotes Female Meiosis II in Response to Fertilization in Caenorhabditis elegans
Maternal MEMI Promotes Female Meiosis II in Response to Fertilization in Caenorhabditis elegans
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DOI：
10.1534/genetics.116.192997
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发表时间：
2016-12-01
期刊：
影响因子：
3.3
通讯作者：
Srayko, Martin
中科院分区：
文献类型：
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作者：
Ataeian, Maryam;Tegha-Dunghu, Justus;Srayko, Martin
在大多数动物中，雌性减数分裂仅在受精后完成。精子的进入与为最终减数分裂过程的启动提供信号有关。然而，此前尚未确定这一过程所需的母体成分。我们报告了编码卵母细胞特异性蛋白的三个高度相似的旁系同源物（memi-1、memi-2、memi-3）的新家族的特征。超态突变 memi-1(sb41) 导致雌性减数分裂 II 无法正常退出；然而，所有三个旁系同源物的丢失会导致“跳过减数分裂II”表型。阻止受精的突变，例如 fer-1(hc1)，也会导致跳过减数分裂 II 表型，这表明 MEMI 蛋白代表指定减数分裂 II 程序的受精后信号的母体成分。 MEMI 蛋白在有丝分裂前被降解，并对 ZYG-11 敏感，ZYG-11 是一种用于基于 cullin 的泛素连接酶活性的底物特异性接头，并且 memi-1(sb41) 突变导致 MEMI-1 蛋白不适当地持续进入有丝分裂。使用 RNAi 筛选 memi-1(sb41) 抑制剂，我们鉴定出精子特异性 PP1 磷酸酶 GSP-3/4，作为 MEMI 途径的假定精子成分。我们还发现 MEMI 和 GSP-3/4 蛋白可以通过免疫共沉淀发生物理相互作用。这些结果表明，精子特异性 PP1 和母体 MEMI 蛋白在受精后以相同的途径发挥作用，以促进适当的减数分裂 II 和向胚胎有丝分裂的转变。
In most animals, female meiosis completes only after fertilization. Sperm entry has been implicated in providing a signal for the initiation of the final meiotic processes; however, a maternal component required for this process has not been previously identified. We report the characterization of a novel family of three highly similar paralogs (memi-1, memi-2, memi-3) that encode oocyte-specific proteins. A hyper-morphic mutation memi-1(sb41) results in failure to exit female meiosis II properly; however, loss of all three paralogs results in a " skipped meiosis II" phenotype. Mutations that prevent fertilization, such as fer-1(hc1), also cause a skipped meiosis II phenotype, suggesting that the MEMI proteins represent a maternal component of a postfertilization signal that specifies the meiosis II program. MEMI proteins are degraded before mitosis and sensitive to ZYG-11, a substrate-specific adapter for cullin-based ubiquitin ligase activity, and the memi-1(sb41) mutation results in inappropriate persistence of the MEMI-1 protein into mitosis. Using an RNAi screen for suppressors of memi-1(sb41), we identified a sperm-specific PP1 phosphatase, GSP-3/4, as a putative sperm component of the MEMI pathway. We also found that MEMI and GSP-3/4 proteins can physically interact via co-immunoprecipitation. These results suggest that sperm-specific PP1 and maternal MEMI proteins act in the same pathway after fertilization to facilitate proper meiosis II and the transition into embryonic mitosis.