Fat-Dachsous signaling in growth control and planar cell polarity

描述（由申请人提供）：本提案概述了一系列实验，旨在检测控制发育生物体生长、细胞死亡和模式形成的重要细胞内途径的调节：由Hippo和Warts蛋白激酶介导。该途径在控制器官生长中起着重要作用，并且该途径的失调是致瘤的，但对其如何控制知之甚少。我们正在集中研究这一途径是如何调节的大型果蝇原钙粘蛋白脂肪和Dachsous。这两种跨膜蛋白的胞外结构域相互结合，通过激活Hippo途径抑制生长。然而，脂肪和Dachsous连接到Hippo通路的机制知之甚少。首先，我们正在解剖脂肪细胞内结构域的活性，并利用它来开发脂肪活性所需分子的体外RNAi筛选。其次，我们正在研究脂肪和Dachsous表达的边界和梯度，以及脂肪和Dachsous在细胞表面上的极化，如何抑制Hippo通路并触发生长。第三，我们正在研究脂肪活性的下游负调节因子，非典型肌球蛋白Dachs/Myosin 29 D及其调节因子Approximated的作用。最后，我们正在研究Hippo通路如何与其他（特别是空间）信息相结合，以调节重要的下游靶点miRNA bantam的表达。

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.