An RNA-binding atypical tropomyosin recruits kinesin-1 dynamically to oskar mRNPs
An RNA-binding atypical tropomyosin recruits kinesin-1 dynamically to oskar mRNPs
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DOI：
10.15252/embj.201696038
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发表时间：
2017-02-01
期刊：
影响因子：
11.4
通讯作者：
Ephrussi, Anne
中科院分区：
文献类型：
--
作者：
Gaspar, Imre;Sysoev, Vasiliy;Ephrussi, Anne
Oskar mRNA在果蝇卵母细胞后极的定位和局部翻译指导胚胎中的腹部图案和生殖系形成。该过程需要募集和精确调节马达蛋白以形成具有运输能力的mRNP。我们发现，后靶向驱动蛋白-1加载奥斯卡mRNP的核出口后，其动力蛋白依赖的运输从护士细胞到卵母细胞。我们证明驱动蛋白-1的募集需要DmTropomyosin 1-I/C亚型，这是一种非典型的RNA结合原肌球蛋白，可直接结合二聚化的奥斯卡3 'UTR。最后，我们表明，奥斯卡mRNP的一个小的，但动态变化的子集得到加载与非活性驱动蛋白-1和电机被激活中期卵子发生的功能化剪接奥斯卡RNA定位元件。这种低效率的，动态招聘的Khc解耦的货物依赖性电机激活构成了一个优化的，协调的机制mRNP运输，通过最大限度地减少干扰与其他货物运输过程和货物相关的动力蛋白和驱动蛋白-1。
Localization and local translation of oskar mRNA at the posterior pole of the Drosophila oocyte directs abdominal patterning and germline formation in the embryo. The process requires recruitment and precise regulation of motor proteins to form transport-competent mRNPs. We show that the posterior-targeting kinesin-1 is loaded upon nuclear export of oskar mRNPs, prior to their dynein-dependent transport from the nurse cells into the oocyte. We demonstrate that kinesin-1 recruitment requires the DmTropomyosin1-I/C isoform, an atypical RNA-binding tropomyosin that binds directly to dimerizing oskar 3'UTRs. Finally, we show that a small but dynamically changing subset of oskar mRNPs gets loaded with inactive kinesin-1 and that the motor is activated during mid-oogenesis by the functionalized spliced oskar RNA localization element. This inefficient, dynamic recruitment of Khc decoupled from cargo-dependent motor activation constitutes an optimized, coordinated mechanism of mRNP transport, by minimizing interference with other cargo-transport processes and between the cargo-associated dynein and kinesin-1.