Fat-Dachsous signaling in growth control and planar cell polarity

描述(申请人提供)：这项提案概述了一系列实验，旨在测试在发育中的生物体中控制生长、细胞死亡和模式的重要细胞内途径的调节：由河马和疣蛋白激酶介导的调节。这一途径在控制器官生长方面发挥着重要作用，而该途径的错误调控会导致肿瘤发生，但人们对其如何控制知之甚少。我们正在集中研究大型果蝇原钙粘附素Fat和Dachsous是如何调控这一途径的。这两种跨膜蛋白的胞外区相互结合，通过激活河马途径抑制生长。然而，连接脂肪和Dachsous与河马途径的机制却知之甚少。首先，我们正在剖析脂肪细胞内域的活性，并利用这一点来开发一种体外RNAi筛选，以寻找脂肪活性所需的分子。其次，我们正在研究Fat和Dachsous表达的边界和梯度，以及由此导致的细胞表面Fat和Dachsous的极化如何抑制河马途径并触发生长。第三，我们正在研究脂肪活性的下游负调控因子，非典型的肌球蛋白Dachs/Myosin29D的作用，其调节因子与之相近。最后，我们正在研究河马途径如何与额外的(特别是空间)信息结合来调控重要的下游靶标miRNA bantam的表达。 与公共健康相关：这些实验测试和提炼了我们关于发育中的有机体如何精确控制它们的生长和模式的知识。这种精确度对正常的人类发育是必不可少的，而这种精确度的失败是许多病理学的基础，包括遗传缺陷和癌症。正在研究的途径是控制人类和其他生物共有的生长的重要手段；由于果蝇的遗传和分子优势，以及进行此类研究的严密性和速度，可以在果蝇身上对其进行有益的研究。

DESCRIPTION (provided by applicant): This proposal outlines a series of experiments designed to test the regulation of an important intracellular pathway for controlling growth, cell death and patterning in developing organisms: that mediated by the Hippo and Warts protein kinases. This pathway plays a major role in controlling organ growth, and misregulation of the pathway is tumorigenic, but little is known about how it is controlled. We are concentrating on how this pathway is regulated by the large Drosophila protocadherins Fat and Dachsous. The extracellular domains of these two transmembrane proteins bind each other, and this suppresses growth by activating the Hippo pathway. However, the mechanisms connecting Fat and Dachsous to the Hippo pathway are poorly understood. First, we are dissecting the activities of the intracellular domains of Fat, and are using that to develop an in vitro RNAi screen for molecules required for Fat activity. Second, we are examining how boundaries and gradients of Fat and Dachsous expression, and the resultant polarization of Fat and Dachsous on cell surfaces, inhibits the Hippo pathway and triggers growth. Third, we are examining the role of a downstream negative regulator of Fat activity, the atypical myosin Dachs/Myosin29D, and its regulator Approximated. Finally, we are examining how the Hippo pathway combines with additional (especially spatial) information to regulate the expression of an important downstream target, the miRNA bantam. PUBLIC HEALTH RELEVANCE: The experiments test and refine our knowledge about how developing organisms precisely control their growth and patterning. Such precision is essential to normal human development, and failure in such precision underlies many pathologies, including genetic defects and cancers. The pathway being studied is an important means for controlling growth that is shared by humans and other organisms; it can be profitably examined in Drosophila because of Drosophila's genetic and molecular advantages, and the rigor and speed with which such studies can be performed.