Cell Polarity and Cytoskeletal Transport in Drosophila

描述(申请人提供)：细胞的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，编码基因活动的转录和翻译调节的RNA的亚细胞定位已经成为导致细胞不对称的主要机制。我们对最初的不对称如何在调节胚胎内的基因活动和细胞身份方面发挥作用的分子理解迅速增长。相比之下，mRNAs细胞质运输和定位的细胞机制还不是很清楚。我们正在研究果蝇卵母细胞指定和分化所需的mRNA决定因素的不对称运输。果蝇卵母细胞展示了一些研究最好的信使核糖核酸定位策略。最值得注意的是，双核mRNA定位于卵母细胞的前部，Oskar mRNA定位于卵母细胞的后部，对于在胚胎中建立轴向模式是至关重要的。遗传分析描述了一种基因产物的途径，这些基因产物以一种循序渐进的方式限制双核和奥斯卡mRNAs的定位。这一途径很可能包括作用于反式作用的特定成分，以调节特定RNA的识别、运输和靶向。转运的其他成分可能不是卵子发生所特有的，目前还没有确定。我们的计划包括三个具体目标。1)我们将研究GFP标记的前后部(A/P)通路的活体运动特性。将使用扰乱或消除运动功能的策略来确定负责运输的电机。2)将进行生化研究，以调查核糖核蛋白复合体的组成，以努力确定(S)与马达蛋白的分子联系。3)鉴定在一种新的筛选中发现的新的基因产物，这些基因产物在卵母细胞中表现出微管依赖的积累。两个新发现的基因座作为RNP运输机制的潜在组成部分在卵母细胞发育中的功能将被研究。

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.