mRNA localization and ER-based protein sorting mechanisms dictate the use of transitional endoplasmic reticulum-Golgi units involved in gurken transport in Drosophila oocytes
mRNA localization and ER-based protein sorting mechanisms dictate the use of transitional endoplasmic reticulum-Golgi units involved in gurken transport in Drosophila oocytes
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DOI：
10.1091/mbc.e04-05-0398
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发表时间：
2004-12-01
影响因子：
3.3
通讯作者：
Rabouille, C
中科院分区：
文献类型：
--
作者：
Herpers, B;Rabouille, C
未来胚胎的前后轴和背腹轴是通过定位gurken mRNA在果蝇卵母细胞内指定的，该mRNA靶向分泌的gurken转化生长因子-合成并转运到同一位点。一个关键的问题是gurken mRNA是否针对一个特殊的胞外通路来实现蛋白质的极性沉积。在这里，我们通过（免疫）电子显微镜显示，9-10期果蝇卵母细胞的胞外通路包括一千个均匀分布的过渡性内质网(tER)-高尔基单位。通过果蝇突变体，我们发现gurken mRNA的定位与gurken在内质网中的高效分类决定了哪些等效的ter -高尔基体单元用于蛋白质的运输和加工。通过mRNA定位选择ter -高尔基基单位使它们彼此独立，代表了一种非传统的方式，通过这种方式，卵母细胞实现了跨膜/分泌蛋白的极化沉积。我们提出这种翻译前机制可能是极化细胞（如神经元）中靶向分泌的一般途径。
The anteroposterior and dorsoventral axes of the future embryo are specified within Drosophila oocytes by localizing gurken mRNA, which targets the secreted Gurken transforming growth factor-a synthesis and transport to the same site. A key question is whether gurken mRNA is targeted to a specialized exocytic pathway to achieve the polar deposition of the protein. Here, we show, by (immuno)electron microscopy that the exocytic pathway in stage 9-10 Drosophila oocytes comprises a thousand evenly distributed transitional endoplasmic reticulum (tER)-Golgi units. Using Drosophila mutants, we show that it is the localization of gurken mRNA coupled to efficient sorting of Gurken out of the ER that determines which of the numerous equivalent tER-Golgi units are used for the protein transport and processing. The choice of tER-Golgi units by mRNA localization makes them independent of each other and represents a nonconventional way, by which the oocyte implements polarized deposition of transmembrane/secreted proteins. We propose that this pretranslational mechanism could be a general way for targeted secretion in polarized cells, such as neurons.