Molecular mechanisms underlying the establishment of cell polarity.

真核生物生命的一个基本特征是细胞极性的建立和维持。分子 马达通过将mRNAs、蛋白质、囊泡和细胞器运送到特定的部位来帮助建立极性。 在细胞内。从单细胞酵母到人类的各种生物都使用mRNA定位偶联 将翻译调控作为蛋白质不对称排序的一种方式。这种现象的普遍程度是 在胚胎、神经元和上皮细胞的发育中得到了最好的说明，在这些细胞中，成千上万的mRNAs在空间上 本地化。当这一过程受到损害时，可能会导致发育和神经障碍。 尽管这个话题很重要，而且这一现象很普遍，但我们缺乏一种机械的 了解信使核糖核酸的定位。我们理解中的一个关键差距与mRNAs的去向有关 定位是由细胞识别的，不同于非定位的mRNAs。除了序列之外 存在于定位的mRNAs中，结合这些mRNAs的蛋白质是它们细胞命运的关键。这 蛋白质复合体负责将定位的mRNAs与分子马达联系起来，并调节它们的 翻译。然而，事实证明，识别这些关键蛋白质是非常具有挑战性的。就其本身而言 自然界中，信使核糖核酸定位的过程是高度动态的。因此，蛋白质-蛋白质和蛋白质-RNA 组装定位信使核糖核蛋白(MRNP)颗粒所需的相互作用很弱 转瞬即逝。这使得使用经典的生化方法来鉴定它们几乎是不可能的； 复合体在提纯步骤中解体。在本申请中，我们提出了解决这一问题的新策略 关键的知识鸿沟。我们建议用于这些研究的模型是具有良好特征的果蝇 黑腹果蝇卵室。在本申请的目标1中，我们建议使用近端生物素结扎来 定义传输粒子的核心成分，并考察这些因素之间的守恒性 苍蝇和哺乳动物。在目标2中，我们建议检验以下假设：颗粒结构称为P 各机构协调mRNAs的本地化及其翻译调控。

A fundamental feature of eukaryotic life is the establishment and maintenance of cellular polarity. Molecular motors help to establish polarity by transporting mRNAs, proteins, vesicles, and organelles to specific sites within the cell. A variety of organisms from the single-celled yeast to humans use mRNA localization coupled with translational regulation as a way to asymmetrically sort proteins. The prevalence of this phenomenon is best illustrated in developing embryos, neurons and epithelial, in which thousands of mRNAs are spatially localized. When this process is compromised, it can result in developmental and neurological disorders. Despite the importance of this topic and the prevalence of this phenomenon, we lack a mechanistic understanding of mRNA localization. A critical gap in our understanding pertains to how mRNAs destined for localization are recognized by the cell and distinguished from non-localizing mRNAs. In addition to sequences present within localizing mRNAs, the proteins that bind these mRNAs are key to their cellular fate. This complex of proteins is responsible for linking localizing mRNAs with molecular motors and for regulating their translation. However, identifying these critical proteins has proven to be extremely challenging. By its very nature, the process of mRNA localization is highly dynamic. Consequently, the protein-protein and protein-RNA interactions required for assembling localizing messenger ribonucleoprotein (mRNP) particles are weak and transient. This has made their identification using classical biochemical approaches almost impossible; the complex falls apart during the purification step. In this application, we propose novel strategies to address this critical knowledge gap. The model we propose to use for these studies is the well-characterized Drosophila melanogaster egg chamber. In Objective 1 of this application, we propose to use proximity biotin ligation to define the core components of transport particles and to examine the conservation of these factors between flies and mammals. In Objective 2, we propose to test the hypothesis that granular structures referred to as P bodies coordinate the localization of mRNAs with their translational regulation.