Cortical granule exocytosis in C-elegans is regulated by cell cycle components including separase
Cortical granule exocytosis in C-elegans is regulated by cell cycle components including separase
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DOI：
10.1242/dev.011361
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发表时间：
2007-11-01
期刊：
影响因子：
4.6
通讯作者：
White, John G.
中科院分区：
文献类型：
--
作者：
Bembenek, Joshua N.;Richie, Christopher T.;White, John G.
在许多生物体中，皮质颗粒在受精后经历胞吐作用，释放出修饰受精卵细胞外覆盖物的货物蛋白。我们鉴定了秀丽隐杆线虫的皮质颗粒，并发现脱颗粒发生在减数分裂纺锤体附近的减数分裂后期 I 附近的波中。之前的研究鉴定了赋予胚胎渗透敏感性表型的基因，认为这是由异常蛋壳形成引起的。其中许多基因是细胞周期机制的组成部分。当我们通过 RNAi 抑制其中几个基因的表达时，我们观察到皮质颗粒运输被破坏，蛋壳无法正常形成。我们得出的结论是，渗透敏感性表型的发生是由于皮质颗粒运输缺陷以及随后形成不渗透蛋壳的缺陷。我们确定分离酶是脱颗粒所需的关键细胞周期成分。分离酶在卵母细胞成熟后的前中期 I 中定位于位于皮质的丝状结构。受精后，分离酶从这些结构中消失，并在后期 I 时出现在皮质颗粒上。sep-1 的 RNAi 除了导致广泛的染色体分离失败之外，还抑制脱颗粒。尽管温度敏感的 sep-1(e2406) 等位基因表现出类似的脱颗粒抑制作用，但它对染色体分离的影响很小。这些观察结果使我们推测 SEP-1 具有两个可分离但协调的功能：调节皮质颗粒胞吐作用和介导染色体分离。
In many organisms, cortical granules undergo exocytosis following fertilization, releasing cargo proteins that modify the extracellular covering of the zygote. We identified cortical granules in Caenorhabditis elegans and have found that degranulation occurs in a wave that initiates in the vicinity of the meiotic spindle during anaphase I. Previous studies identified genes that confer an embryonic osmotic sensitivity phenotype, thought to result from abnormal eggshell formation. Many of these genes are components of the cell cycle machinery. When we suppressed expression of several of these genes by RNAi, we observed that cortical granule trafficking was disrupted and the eggshell did not form properly. We conclude that osmotic sensitivity phenotypes occur because of defects in trafficking of cortical granules and the subsequent formation of an impermeable eggshell. We identified separase as a key cell cycle component that is required for degranulation. Separase localized to cortically located filamentous structures in prometaphase I upon oocyte maturation. After fertilization, separase disappeared from these structures and appeared on cortical granules by anaphase I. RNAi of sep- 1 inhibited degranulation in addition to causing extensive chromosomal segregation failures. Although the temperature- sensitive sep- 1( e2406) allele exhibited similar inhibition of degranulation, it had minimal effects on chromosome segregation. These observations lead us to speculate that SEP- 1 has two separable yet coordinated functions: to regulate cortical granule exocytosis and to mediate chromosome separation.