Cell Polarity and Cytoskeletal Transport in Drosophila

描述（由申请人提供）：细胞极性或不对称是所有生物发育和形态发生的基础。在过去的二十年中，编码基因活性转录和翻译调节因子的rna的亚细胞定位已成为细胞不对称的主要机制。我们对胚胎中调节基因活动和细胞身份的初始不对称如何发挥作用的分子理解已经迅速发展。相比之下，细胞质运输和mrna定位的细胞机制尚不清楚。我们正在研究果蝇卵母细胞规范和分化所需的mRNA决定因素的不对称运输。果蝇卵母细胞展示了mRNA定位策略的一些最好的研究实例。最值得注意的是，Bicoid mRNA定位于卵母细胞的前侧，Oskar mRNA定位于卵母细胞的后侧，这对于在胚胎中建立轴向模式至关重要。遗传分析描述了一种基因产物的途径，该途径以逐步的方式限制Bicoid和Oskar mrna的定位。这一途径很可能包括通过反式作用来调节特定rna的识别、运输和靶向的特定成分。运输的其他组成部分可能不是卵子发生所特有的，尚未确定。我们的计划包括三个具体目标。1)我们将表征gfp标记的前/后（A/P）通路组分的体内运动性。负责运输的电机将使用策略来确定，以破坏或消除电机功能。2)将继续进行生化研究，以研究RNP复合物的组成，以确定与运动蛋白的分子联系。3)表征在新筛选中发现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在卵母细胞发育中作为RNP转运机制的潜在组成部分的功能将被研究。

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.