Cell Polarity and Cytoskeletal Transport in Drosophila

描述（由申请人提供）：细胞极性或不对称性是所有生物体发育和形态发生的基础。在过去的二十年里，编码基因活性的转录和翻译调节因子的RNA的亚细胞定位已经成为细胞不对称性的主要机制。我们对最初的不对称性如何在胚胎内调节基因活动和细胞身份方面发挥作用的分子理解已经迅速发展。相比之下，作为mRNA胞质转运和定位的基础的细胞机制还没有得到很好的理解。我们正在研究果蝇卵母细胞的规格和分化所需的mRNA决定簇的不对称运输。果蝇卵母细胞展示了一些mRNA定位策略的最佳研究实例。最值得注意的是，Bicoid mRNA定位于卵母细胞的前部，Oskar mRNA定位于卵母细胞的后部，这对于在胚胎中建立轴向模式至关重要。遗传分析已经描述了一种基因产物的途径，其以逐步的方式作用以限制Bicoid和Oskar mRNA的定位。该途径最有可能包括反式作用以调节特定RNA的识别、转运和靶向的特定组分。其他运输成分可能不是卵子发生所特有的，尚待鉴定。我们的计划包括三个具体目标。1)我们将在体内的前/后（A/P）通路的GFP标记的组件的运动特性。负责运输的马达将使用中断或消除马达功能的策略来确定。2)将进行生物化学研究，以研究RNP复合物的组成，以确定与马达蛋白的分子连接。3)表征在新筛选中鉴定的在卵母细胞中表现出微管依赖性积累的新基因产物。两个新发现的基因座的功能作为潜在的组成部分，在卵母细胞发育中的RNP运输机制将进行调查。

DESCRIPTION (provided by applicant): Cell polarity or asymmetry is fundamental to the development and morphogenesis of all organisms. Over the past two decades, the subcellular localization of RNAs that encode transcription and translational regulators of gene activity has emerged as a major mechanism underlying cellular asymmetries. Our molecular understanding of how the initial asymmetry plays out in terms of regulating gene activities and cell identities within an embryo has grown rapidly. By comparison, the cellular mechanisms that underlie the cytoplasmic transport and localization of mRNAs are not well understood. We are studying the asymmetric transport of mRNA determinants required for the specification and differentiation of the Drosophila oocyte. The Drosophila oocyte exhibits some of the best studied examples of the mRNA localization strategy. Most notably, the localization of Bicoid mRNA to the anterior and Oskar mRNA to the posterior of the oocyte is critical for establishing axial patterning in the embryo. Genetic analysis has described a pathway of gene products that act in a stepwise fashion to restrict the localization of Bicoid and Oskar mRNAs. This pathway most likely includes specific components that act in trans to regulate the recognition, transport, and targeting of specific RNAs. Other components of transport may not be specific to oogenesis and are yet to be identified. Our plan includes three specific aims. 1) We will characterize the in vivo motility of GFP-tagged components of the anterior/posterior (A/P) pathway. The motors responsible for transport will be determined using strategies to disrupt or eliminate motor function. 2) Biochemical studies will be pursued to investigate the composition of the RNP complexes in an effort to identify the molecular link(s) to motor proteins. 3) To characterize new gene products identified in a novel screen that exhibit microtubule-dependent accumulation in the oocyte. The function of two newly identified loci as potential components of the RNP transport machinery in oocyte development will be investigated.