Planar Cell Polarity and the Cytoskeleton

描述(申请人提供)：平面细胞极性和细胞骨架平面细胞极性(PCP)信号调节上皮平面内极性的建立。信号传递的结果是多种多样的，包括细胞命运的决定，不对称但高度排列的结构的产生(例如，人类内耳的静纤毛或苍蝇翅膀上的毛发)，或者在脊椎动物原肠发育过程中收敛伸展过程中细胞的定向迁移。PCP由非规范的FZ/Planar Cell极性通路控制，在该通路中，Wnt通过Frizzled型受体发出信号，导致核反应，以及Rho Kinase介导的细胞骨架变化。PCP信号最初是在果蝇中发现的，也是研究得最好的，主要是因为果蝇作为模型系统的多功能性，因为它的遗传冗余度很低。在果蝇中，PCP对于肌动蛋白翼毛的定向和眼睛小眼的极化是必不可少的，这需要一组光感受器细胞的高度协调运动(小眼旋转)。因此，果蝇PCP信号和脊椎动物收敛延伸的关键是细胞骨架重排和细胞迁移过程。这些过程的中心是Rho Kinase(果蝇中的Rho，Drok)，其突变或显性阴性形式分别导致小眼旋转/迁移和会聚伸展/神经管缺陷。这项提案侧重于采用生化和遗传方法来识别和表征新的五氯苯酚成分和细胞骨架的调节因子。在全基因组筛选中，我们使用磷酸化诱导凝胶移位分析确定了直接的Drok底物。我们将使用体内RNAi、突变分析和与已知途径组件的遗传相互作用分析来表征候选基因。我们建议详细研究它们在Rho Kinase和PCP信号转导中的作用机制。使用上述策略来研究PCP信号的机械方面，以及发现与细胞反应的新联系，将扩展我们对早期发育的知识。由于PCP基因网络在果蝇、海鞘动物和哺乳动物中的保守性，这项拟议的研究将对理解PCP在脊椎动物中的建立和相关的形态发生过程具有直接的重要意义。公共卫生相关性：果蝇和人类细胞之间的通讯机制非常保守，非常相似。我们利用果蝇来研究细胞通讯如何影响细胞运动。缺乏这种沟通可能会导致严重的出生缺陷，如神经管开放(如脊柱裂)。

DESCRIPTION (provided by applicant): Planar cell polarity and the cytoskeleton Planar cell polarity (PCP) signaling regulates the establishment of polarity within the plane of an epithelium. The results of signaling are as diverse as the determination of cell fates, the generation of asymmetric, but highly aligned structures (e.g. stereocilia in the human inner ear or hairs on a fly wing), or the directional migration of cells during convergent extension during vertebrate gastrulation. PCP is governed by the non-canonical Fz/Planar Cell Polarity pathway, in which a Wnt signals through a Frizzled receptor leading to nuclear responses, as well as to cytoskeletal changes mediated by Rho Kinase. PCP signaling was originally discovered and is best studied in Drosophila, mainly because of the versatility of the fly as model system due to its low genetic redundancy. In Drosophila, PCP is essential for the orientation of the actin wing hairs and the polarization of the ommatidia in the eye, requiring highly coordinated movement of groups of photoreceptor cells (ommatidial rotation). Thus, key to PCP signaling in flies, and to convergent extension in vertebrates, are cytoskeletal rearrangements and cell migration processes. Central to these processes is Rho Kinase (Rock, Drok in Drosophila), mutations in which or dominant negative forms of which lead to ommatidial rotation/migration and convergent extension/neural tube defects in flies and fish, respectively. This proposal focuses on biochemical and genetic approaches to identify and characterize new PCP components and regulators of the cytoskeleton. In a genome wide screen we identified direct Drok substrates using a phosphorylation induced gel-shift assay. We will characterize the candidates using in vivo RNAi, mutational analysis and genetic interaction assays with known pathway components. We propose to study their mechanism of action with respect to Rho Kinase and PCP signaling in detail. Using the above strategies to work out mechanistic aspects of PCP signaling as well as to discover new links to cellular responses will extend our knowledge of early development. Due to the conservation of the PCP gene network in organisms as diverse as flies, ascidians and mammals, the proposed research will be of immediate importance for the understanding of the establishment of PCP and related morphogenetic processes in vertebrates. PUBLIC HEALTH RELEVANCE: The mechanism of communication between cells of the fruitfly Drosophila and humans is well conserved and very similar. We make use of Drosophila to study how cell communication affects cell movement. Lack of such communication can lead to severe birth defects such as open neural tubes (e.g. spina bifida).