Control of cell number in developing retina

描述（由申请人提供）：功能性眼睛的成功发育不仅需要指定各种视网膜细胞类型的细胞分化程序，还需要确定视网膜中细胞数量的大小控制机制。我的实验室正在采取分子，遗传和生物化学方法来了解指定视网膜细胞数量的分子机制。利用果蝇的复眼作为实验模型，我的实验室最近发现了一个关键的信号通路，通过协调调节细胞增殖和细胞死亡来控制视网膜细胞数量。这条通路由三个肿瘤抑制基因定义，它们通常负调控视网膜细胞数量：hippo（hpo）、萨尔瓦多（sav）和wts（wts）。Hpo是一种Ser/Thr激酶，与含有WW和卷曲螺旋结构域的接头蛋白Sav结合并使其磷酸化。Hpo和Sav之间的相互作用反过来增强了Hpo对Wts的激酶活性。该途径的失活导致细胞周期调节因子Cyclin E和细胞死亡抑制因子diap 1的转录升高，从而导致增殖增加和凋亡减少。此外，该途径似乎在哺乳动物中发挥进化保守的作用。在这里，我们提出了三个具体的目标，以进一步了解的功能和调节的Hpo途径在视网膜大小控制。在第一个具体的目标，我们将确定Hpo途径调节diap 1转录的分子机制，通过确定Hpo响应转录因子和分析其调控模式。在第二个具体目标中，我们将确定Hpo信号转导途径的细胞机制。在第三个具体目标中，我们将使用生物化学，酵母双杂交和遗传方法来鉴定Hpo途径的其他组分。除了揭示眼睛发育的基本机制外，我们的研究对其他组织的发育具有普遍意义。

DESCRIPTION (provided by applicant): Successful development of a functional eye requires not only cell-differentiation programs that specify various retina cell types, but also size-control mechanisms that determine the number of cells in the retina. My laboratory is taking molecular, genetic and biochemical approaches to understand the molecular mechanisms that specify retina cell number. Using the compound eye of Drosophila as an experimental model, my laboratory has recently identified a key signaling pathway that controls retina cell number by coordinately regulating cell proliferation and cell death. This pathway is defined by three tumor suppressor genes that normally negatively regulate retina cell number: hippo (hpo), salvador (sav) and warts (wts). Hpo, a Ser/Thr kinase, binds to and phosphorylates Sav, an adaptor protein containing WW and coiled-coil domains. Interactions between Hpo and Sav in turn potentiate the kinase activity of Hpo towards Wts. Inactivation of this pathway results in elevated transcription of the cell cycle regulator Cyclin E and the cell death inhibitor diap1, thus leading to increased proliferation and reduced apoptosis. Moreover, this pathway appears to play an evolutionarily conserved role in mammals. Here we propose three specific aims to further understand the function and regulation of the Hpo pathway in retina size-control. In the first specific aim, we will determine the molecular mechanisms by which the Hpo pathway regulates diap1 transcription by identifying the Hpo-responsive transcription factor and analyzing its mode of regulation. In the second specific aim, we will determine the cellular mechanism of the Hpo signal transduction pathway. In the third specific aim, we will use biochemical, yeast two-hybrid and genetic approaches to identify additional components of the Hpo pathway. Besides revealing basic mechanisms of eye development, our studies have general implications for the development of other tissues.