Mechanisms of RNA localization in oocytes

 描述(申请人提供)：在卵子中建立极性可以被视为胚胎模式的最早步骤。因此，早期卵裂细胞之间细胞命运的差异是受精前卵细胞质中信息分子不对称分布的结果。在各种各样的生物体中，这种极性的基础可以通过以mRNA的形式定位的母体决定因素来提供。在脊椎动物中，Vg1 mRNA是一个在胚胎模式中发挥作用的局部mRNA的突出例子。Vg1蛋白在卵子植物半球的限制表达对胚胎的正确模式至关重要，使Vg1 mRNA的定位成为理解母体分子如何定位影响模式和极性的重要模型。本研究项目的目的是研究将mRNAs定向到细胞质的特定区域以产生细胞和发育极性的机制。我们对将母体mRNA分子定向到非洲爪哇卵母细胞营养皮质的分子途径的研究进展，为这项研究奠定了基础。通过开发跟踪活卵母细胞中mRNA运输的方法和分离运输复合体的生化策略，我们的实验发现了该途径中的新步骤，并揭示了细胞运输机制的新组件。我们目前的提案试图利用这些发现来描绘将母体mRNAs传递到细胞质目的地的分子途径。提出了三个具体的目标：在目标1中，我们将分析驱动植物RNP运输颗粒组装的分子相互作用，在目标2中，我们将确定在RNA运输过程中调节方向性的机制，在目标3中，我们将研究控制定位的RNA在卵母细胞皮质保留的机制。这项拟议的研究旨在揭示mRNA分子在细胞内运输以产生空间受限的蛋白质表达的机制，并将为了解发育信号在脊椎动物胚胎中的空间分布提供洞察。这项工作将影响与人类健康相关的问题，如出生缺陷，以及与RNA运输缺陷和局部蛋白质合成有关的神经疾病。

 DESCRIPTION (provided by applicant): Establishment of polarity in the egg can be viewed as the earliest step in embryonic patterning. Thus, differences in cell fate among the early cleavage cells are a consequence of asymmetric distributions of informational molecules in the egg cytoplasm before fertilization. In a wide variety of organisms, the basis for such polarity can be provided by localized maternal determinants in the form of mRNA. Among vertebrates, Vg1 mRNA is a prominent example of a localized mRNA that plays a role in embryonic patterning. Restricted expression of Vg1 protein in the vegetal hemisphere of the egg is critical for correct patterning of the embryo, making localization of Vg1 mRNA an important model for understanding how maternal molecules are localized to influence pattern and polarity. The goal of this research project is to investigate the mechanisms that direct targeting of mRNAs to specific regions of the cell cytoplasm to generate cell and developmental polarity. The foundation for this investigation has been laid by our progress studying the molecular pathway that directs maternal mRNA molecules to the vegetal cortex of the Xenopus oocyte. Through development of approaches to track mRNA transport in live oocytes and biochemical strategies to isolate transport complexes, our experiments have uncovered new steps in the pathway and revealed new components of the cellular transport machinery. Our current proposal seeks to capitalize on these findings in order to delineate the molecular pathway that orchestrates delivery of maternal mRNAs to their cytoplasmic destinations. Three specific aims are proposed: In Aim 1, we will analyze the molecular interactions that drive vegetal RNP transport granule assembly, in Aim 2, we will determine the mechanisms that regulate directionality during RNA transport and in Aim 3 we will investigate the mechanisms that control retention of localized RNAs at the oocyte cortex. The proposed research is designed to reveal the mechanisms by which mRNA molecules are transported within cells to generate spatially restricted protein expression, and will provide insight into how developmental signals are spatially distributed in the vertebrate embryo. This work will impact issues related to human health such as birth defects, as well as neurological diseases that have been linked to defective RNA transport and localized protein synthesis.