Live imaging of endogenous RNA reveals a diffusion and entrapment mechanism for nanos mRNA localization in Drosophila
Live imaging of endogenous RNA reveals a diffusion and entrapment mechanism for nanos mRNA localization in Drosophila
复制标题
DOI：
10.1016/s0960-9822(03)00451-2
复制
发表时间：
2003-07-15
期刊：
影响因子：
9.2
通讯作者：
Gavis, ER
中科院分区：
文献类型：
--
作者：
Forrest, KM;Gavis, ER
背景：纳米（nanos）mRNA在果蝇胚胎后极的定位指导纳米蛋白的局部合成，这对于前后体轴的模式形成以及生殖细胞功能至关重要。虽然纳米RNA由卵巢滋养细胞合成，并在卵子发生后期出现在卵母细胞的后极，但这种RNA转运并锚定在卵母细胞后部的机制尚不清楚。
结果：通过用绿色荧光蛋白（GFP）标记内源性纳米RNA，我们能够追踪活卵母细胞中纳米定位的动态路径。我们证明纳米定位在滋养细胞排空后立即启动，通过微管依赖的细胞质运动增强的扩散作用，将纳米RNA从滋养细胞转运到卵母细胞后部。在后部，纳米通过与位于后部的生殖质形成颗粒状结合而被捕获。在后部，纳米RNA与生殖质形成的复合物通过肌动蛋白依赖的锚定作用，在细胞质快速运动的情况下维持定位。
结论：这些结果揭示了一种基于扩散的、后期作用的纳米mRNA长距离运输的后部定位机制。这种机制不同于基于定向运输的定位机制，它依赖于RNA的整体运动。
Background: Localization of nanos mRNA to the posterior pole of the Drosophila embryo directs local synthesis of Nanos protein that is essential for patterning of the anterior-posterior body axis and germ cell function. While nanos RNA is synthesized by the ovarian nurse cells and appears at the posterior pole of the ooctye late in oogenesis, the mechanism by which this RNA is translocated to and anchored at the oocyte posterior is unknown.Results: By labeling endogenous nanos RNA with GFP, we have been able to follow the dynamic pathway of nanos localization in living oocytes. We demonstrate that nanos localization initiates immediately upon nurse cell dumping, whereby diffusion, enhanced by microtubule-dependent cytoplasmic movements, translocates nanos RNA from the nurse cells to the ooctye posterior. At the posterior, nanos is trapped by association, in particles, with the posteriorly localized germ plasm. Actin-dependent anchoring of nanos RNA complexed to the germ plasm at the posterior maintains localization in the face of rapid cytoplasmic movements.Conclusions: These results reveal a diffusion-based, late-acting posterior localization mechanism for longrange transport of nanos mRNA. This mechanism differs from directed transport-based localization mechanisms in its reliance on bulk movement of RNA.