The CPEB translational regulator, Orb, functions together with Par proteins to polarize the Drosophila oocyte
The CPEB translational regulator, Orb, functions together with Par proteins to polarize the Drosophila oocyte
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DOI：
10.1371/journal.pgen.1008012
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发表时间：
2019-03-01
期刊：
影响因子：
4.5
通讯作者：
Schedl, Paul
中科院分区：
文献类型：
--
作者：
Barr, Justinn;Charania, Sofia;Schedl, Paul
orb 是 CPEB 翻译调节因子家族的创始成员，在果蝇卵子发生过程中的多个步骤中都是必需的。先前的研究表明，在卵子发生中期需要 orb 来翻译后/种系决定簇 oskar mRNA 和背腹决定簇 gurken mRNA。在这里，我们报告说，orb 还在微管网络 (MT) 极化中这些轴决定因素的上游发挥作用。在 oskar 和 gurken 翻译激活之前，卵母细胞 MT 网络被复极化。卵母细胞后部的MT组织中心被解体，并在卵母细胞前部建立新的MT网络。复极化取决于前部（顶端）和后部（基底）Par 蛋白之间的交叉调节相互作用。我们表明，卵母细胞的复极化也需要 orb，而该 orb 是 Par 蛋白正常发挥功能所必需的。 orb 在基因上与 aPKC 和 cdc42 相互作用，并且在 orb 活性受损的卵室中，Par-1 和 aPKC 蛋白以及 aPKC mRNA 定位错误。此外，与 cdc42(-) 一样，Par 蛋白定位的缺陷似乎与皮质肌动蛋白细胞骨架的异常有关。这些异常还破坏了 Spectraplakin Shot 和微管负端结合蛋白 Patronin 的定位。这两种蛋白质在 MT 网络的复极化中发挥着关键作用。 作者摘要 果蝇卵和胚胎中极性轴的规范取决于卵子发生中期微管 (MT) 和肌动蛋白细胞骨架的正确组织。在此期间，卵母细胞后部的MT组织中心被解体，并在卵母细胞的前部和前外侧皮层建立MT网络。我们表明 CPEB 翻译因子 orb 在 MT 网络重组中发挥着关键作用。在 MT 重组过程中，orb 似乎在多个层面上发挥作用。 orb 与编码 Par 蛋白、aPKC 和 cdc42 的基因发生遗传相互作用，并破坏 Par-1 和 aPKC 在卵母细胞内的定位。 orb 在组织皮质肌动蛋白细胞骨架中也发挥着重要作用。肌动蛋白细胞骨架的缺陷破坏了 Shot 和 Patronin 的皮质关联，而 Shot 和 Patronin 负责前 MT 网络的组装成核。
orb is a founding member of the CPEB family of translational regulators and is required at multiple steps during Drosophila oogenesis. Previous studies showed that orb is required during mid-oogenesis for the translation of the posterior/germline determinant oskar mRNA and the dorsal-ventral determinant gurken mRNA. Here, we report that orb also functions upstream of these axes determinants in the polarization of the microtubule network (MT). Prior to oskar and gurken translational activation, the oocyte MT network is repolarized. The MT organizing center at the oocyte posterior is disassembled, and a new MT network is established at the oocyte anterior. Repolarization depends upon cross-regulatory interactions between anterior (apical) and posterior (basal) Par proteins. We show that repolarization of the oocyte also requires orb and that orb is needed for the proper functioning of the Par proteins. orb interacts genetically with aPKC and cdc42 and in egg chambers compromised for orb activity, Par-1 and aPKC protein and aPKC mRNA are mislocalized. Moreover, like cdc42(-), the defects in Par protein localization appear to be connected to abnormalities in the cortical actin cytoskeleton. These abnormalities also disrupt the localization of the spectraplakin Shot and the microtubule minus-end binding protein Patronin. These two proteins play a critical role in the repolarization of the MT network.Author summary The specification of polarity axes in the Drosophila egg and embryo depends on the proper organization of the microtubule (MT) and actin cytoskeleton during mid-oogenesis. During this period, the MT organizing center at the posterior of the oocyte is disassembled and a MT network is established at the anterior and anterior-lateral cortex of the oocyte. We show that the CPEB translation factor orb plays a critical role in the reorganization of the MT network. orb appears to function at several levels during MT reorganization. orb interacts genetically with genes encoding Par proteins, aPKC and cdc42, and disrupts the localization of Par-1 and aPKC within the oocyte. orb also plays an important role in organizing the cortical actin cytoskeleton. The defects in the actin cytoskeleton disrupt the cortical association of Shot and Patronin, which are responsible for nucleating the assembly of the anterior MT network.