A Novel Signaling Pathway in Planar Cell Polarity Establishment

描述(申请人提供)：上皮细胞通常在两个轴上极化，在顶端-基底轴和在上皮平面内的第二轴，通常称为 平面CEL极性(或PCP)。哺乳动物PCP的经典例子包括皮肤发育的毛芽取向或内部器官的细胞排列，如内耳上皮及其感觉纤毛。在果蝇中，所有的成体角质结构都显示出PCP特征。果蝇PCP建立的研究为研究发育模式和疾病中PCP的建立提供了范例。对果蝇的分析已经建立了一个保守的分子盒和锚定在Frizzleed(FZ)跨膜蛋白和相关调控因子周围的途径。这种FZ/PCP信号通路及其核心调控元件在整个进化过程中是保守的，不仅在上皮器官中调节细胞极化的许多方面，而且在哺乳动物原肠和神经形成过程中也调节间充质细胞的定向迁移。虽然核心因子FZ/PCP之间细胞内相互作用的分子机制已开始被了解，但对PCP跨整个器官协调极性的长程调控机制知之甚少。这一应用的范围是为了跟踪有趣的观察结果，这些观察表明PCP的长程协调需要FZ蛋白(通常是Wnt家族配体的受体)本身作为配体，通过与四通路跨膜受体Van Gogh(Vang；在哺乳动物中类似Vang)结合来激活一条新的信号通路。基于有趣的初步数据，我们提出了确定Vang下游作用的这一新途径的组件并开始组装的具体目标。我们已经建立了几种分析方法来解决这个问题：将结合全基因组在体内对果蝇的遗传研究和细胞培养生化分析来实现我们的目标。由于全球长程PCP型极化事件在很大程度上是模糊的，我们的应用将提供第一个洞察力(S)对作用于Fz结合的长程线索下游的Vang信号通路的机制的洞察。PCP的建立和FZ-Vang因子与几种医学异常有关，包括耳聋、癌症(该通路的几个组成部分是原癌基因或肿瘤抑制因子)、多囊肾病和纤毛疾病。因此，在本申请中获得的信息既将促进我们对PCP和器官模式的理解，也将在几种疾病背景下具有医学意义。

DESCRIPTION (provided by applicant): Epithelial cells are often polarized in two axes, in the apical-basal axis and in a second axis within the plane of the epithelium, generally referred to as Planar Cel Polarity (or PCP). Classical examples of PCP in mammals include aspects of skin development with hair bud orientation or cellular arrangements in internal organs, like the inner ear epithelium with its sensory cilia. In Drosophila, all adult cuticular structures display PCP features. The study of PCP establishment in Drosophila serves as a paradigm for PCP establishment in developmental patterning and disease. Analyses in Drosophila have established a conserved molecular cassette and pathway anchored around the Frizzled (Fz) trans-membrane protein and associated regulatory factors. This Fz/PCP signaling pathway and its core regulatory components are conserved throughout evolution regulating many aspects of cellular polarization not only in epithelial organs, but also in directed cell migration of mesenchymal cells during mammalian gastrulation and neurulation. Although the molecular mechanisms of the intracellular interactions among the core Fz/PCP factors are beginning to be understood, very little is known about the mechanisms of long-range PCP regulation coordinating polarity across whole organs. The scope of this application is to follow-up on interesting observations that suggest that long-range PCP coordination requires that the Fz protein (generally a receptor for Wnt-family type ligands) acts as a ligand itself, activating a novel signaling pathway by binding to the four-pass trans-membrane receptor Van Gogh (Vang; Vang-like in mammals). Based on interesting preliminary data, we propose as Specific Aims to identify the components of and start assembling this novel pathway, acting downstream of Vang. We have established several assays that will allow us to address this: A combination of genome-wide genetic in vivo studies in Drosophila and cel culture biochemical analyses will be performed to achieve our goals. As the global long- range PCP-type polarization events are largely obscure, our application will provide the first insight(s) into the mechanism of a Vang-signaling pathway that acts downstream of Fz-binding interpreting long-range cues. PCP establishment and the Fz-Vang factors have been linked to several medical abnormalities, including deafness, cancer (several components of the pathway are proto-oncogenes or tumor suppressors), poly cystic kidney disease, and ciliopathies. As, such the information acquired in this application will both advance our understanding of PCP and organ patterning, and will also be of medical relevance in several disease contexts.