Rab6 is required for the exocytosis of cortical granules and the recruitment of separase to the granules during the oocyte-to-embryo transition in Caenorhabditis elegans
Rab6 is required for the exocytosis of cortical granules and the recruitment of separase to the granules during the oocyte-to-embryo transition in Caenorhabditis elegans
复制标题
DOI：
10.1242/jcs.116400
复制
发表时间：
2012-12-01
影响因子：
4
通讯作者：
Kimura, Akatsuki
中科院分区：
文献类型：
--
作者：
Kimura, Kenji;Kimura, Akatsuki
受精后胚胎表面的重塑是由高尔基复合体衍生的皮质颗粒的胞吐作用介导的。这一过程对于许多物种的卵母细胞到胚胎的转变至关重要。然而，受精信号如何到达皮质颗粒及时胞吐在很大程度上是未知的。在秀丽隐杆线虫，招聘分离酶，受精信号的下游效应，皮质颗粒的胞吐作用是必不可少的，因为分离酶是膜融合所需的。然而，招募分离酶的皮质颗粒的分子仍然不明。在这项研究中，我们发现Rab 6，一个高尔基体相关的GT3，是必不可少的招募分离酶的皮质颗粒在C。线虫胚胎敲除C. elegans，导致皮质颗粒胞吐作用的膜融合步骤失败。使用一个转基因株，表达GFP融合RAB-6.1，我们发现RAB-6.1暂时共定位与分离酶的皮质颗粒上几分钟，然后分散在细胞质伴随膜融合。我们发现，RAB-6.1，以及细胞周期蛋白依赖性激酶（CDK）-1和后期促进复合物/细胞周期体（APC/C），需要招募分离酶的皮质颗粒。与CDK-1、APC/C和SEP-1不同，染色体分离过程不需要RAB-6.1。结果表明RAB-6.1是胞吐作用的膜融合步骤和分离酶向颗粒的募集所必需的。因此，RAB-6.1是一个重要的分子，在卵母细胞向胚胎过渡的皮质颗粒的及时胞吐。
Journal of Cell Science Remodeling of the embryo surface after fertilization is mediated by the exocytosis of cortical granules derived from the Golgi complex. This process is essential for oocyte-to-embryo transition in many species. However, how the fertilization signal reaches the cortical granules for their timely exocytosis is largely unknown. In Caenorhabditis elegans, the recruitment of separase, a downstream effector of the fertilization signal, to the cortical granules is essential for exocytosis because separase is required for membrane fusion. However, the molecule that recruits separase to the cortical granules remains unidentified. In this study, we found that Rab6, a Golgi-associated GTPase, is essential to recruit separase to the cortical granules in C. elegans embryos. Knockdown of the rab-6.1 gene, a Rab6 homolog in C. elegans, resulted in failure of the membrane fusion step of cortical granule exocytosis. Using a transgenic strain that expresses GFP-fused RAB-6.1, we found that RAB-6.1 temporarily co-localized with separase on the cortical granules for a few minutes and then was dispersed in the cytoplasm concomitantly with membrane fusion. We found that RAB-6.1, as well as cyclin-dependent kinase (CDK)-1 and anaphase promoting complex/cyclosome (APC/C), was required to recruit separase to the cortical granules. RAB-6.1 was not required for the chromosome segregation process, unlike CDK-1, APC/C and SEP-1. The results indicate that RAB-6.1 is required specifically for the membrane fusion step of exocytosis and for the recruitment of separase to the granules. Thus, RAB-6.1 is an important molecule for the timely exocytosis of the cortical granules during oocyte-to-embryo transition.