Control of Cell Number in Developing Retina

项目摘要/摘要 我的长期科学目标是了解决定视网膜细胞数量的分子机制。vbl.使用 以果蝇复眼为实验模型，本实验室发现了河马通路 作为这一进程的核心机制。河马信号转导通路的核心是一条信号转导通路 其中，Ste20激酶河马(HPO)磷酸化并激活NDR家族肌瘤(WTS)。 反过来，WTS通过将癌蛋白York kie(Yki)排除在细胞核之外，使其磷酸化并失活， 在那里它通常作为DNA结合转录因子扇贝(SD)的辅助激活因子发挥作用。我们的 研究进一步证实了河马途径在控制哺乳动物器官大小方面的关键作用， 强调果蝇作为发现普遍发育的有力模型的重要性 机械装置。 尽管最近取得了进展，但我们对河马信号的组成、机制和调控的理解 仍然不完整。我们最近的许多努力都集中在寻找丢失的组件上 河马途径，最终目标是定义一个完整的河马信号网络。在目前的拨款中 在此期间，我们填补了我们对河马途径理解的几个关键空白，包括一个功能链接 在河马信号和天然免疫受体Toll之间，血影蛋白作为河马的上游调节因子 肌动球蛋白调节的信号转导，STRIPAK磷酸酶介导的HPO活性的自身抑制 复合体，一种与组蛋白甲基转移酶复合体HPO冗余发挥功能的HPO样激酶 通过yki激活河马靶基因的转录，并招募锌指转录抑制物 抑制河马靶基因的转录。我们进一步为河马研究社区做出了贡献 通过开发一组苍蝇种群，可以通过以下方式明确地验证任何河马途径调节器 严格的遗传上位性测试。 在下一个授权期内，我们会透过 遵循特定的目标。首先，我们将剖析血影蛋白和血影蛋白 肌动蛋白细胞骨架调节发育组织中的河马信号。第二，我们将识别上游 通过拮抗STRIPAK磷酸酶活性调节河马信号的肿瘤抑制因子 很复杂。这些研究将使我们能够确定STRIPAK磷酸酶复合体是如何发挥中枢作用的 将不同的上游输入整合到河马路径的枢纽。最后，我们将描述新型调节器的特征 从敏化筛选中分离的河马信号增强部分河马表型丢失的突变 在眼睛里。这种不偏不倚的方法将揭示以前未曾预见的监管机构/潜在机制 河马小路。除了揭示眼睛发育的基本机制外，拟议的研究还将 对其他组织的发育具有普遍意义。

Project Summary / Abstract My long-term scientific goal is to understand the molecular mechanisms that specify retina cell number. Using the compound eye of Drosophila as an experimental model, my laboratory has discovered the Hippo pathway as a central mechanism underlying this process. The core of the Hippo pathway comprises a kinase cascade in which the Ste20 kinase Hippo (Hpo) phosphorylates and activates the NDR family kinase Warts (Wts). Wts, in turn, phosphorylates and inactivates the oncoprotein Yorkie (Yki) by excluding it from the nucleus, where it normally functions as a coactivator for the DNA-binding transcription factor Scalloped (Sd). Our research further established a critical role for the Hippo pathway in controlling organ size in mammals, underscoring the importance of Drosophila as a powerful model to discover universal developmental mechanisms. Despite recent progress, our understanding of the composition, mechanism and regulation of Hippo signaling remains incomplete. Much of our recent efforts have focused on discovering the missing components of the Hippo pathway, with the ultimate goal of defining a complete Hippo signaling network. In the current grant period, we have filled several key gaps in our understanding of the Hippo pathway, including a functional link between Hippo signaling and the innate immunity receptor Toll, spectrin as an upstream regulator of Hippo signaling by modulating actomyosin, autoinhibition of Hpo activity mediated by the STRIPAK phosphatase complex, a Hpo-like kinase that functions redundantly with Hpo, a histone methyltransferase complex recruited by Yki to activate the transcription of Hippo target genes, and a zinc finger transcriptional repressor recruited by Sd to repress the transcription of Hippo target genes. We further contributed to the Hippo research community by developing a set of fly stocks that can be used to unequivocally validate any Hippo pathway regulators through rigorous genetic epistasis test. In the next grant period, we will further elucidate the molecular underpinnings of the Hippo pathway through the following specific aims. First, we will dissect the molecular and cellular mechanisms by which spectrin and actomyosin cytoskeletons regulate Hippo signaling in developing tissues. Second, we will identify upstream tumor suppressors that regulate Hippo signaling by antagonizing the activity of the STRIPAK phosphatase complex. These studies will allow us to define how the STRIPAK phosphatase complex functions as a central hub that integrates diverse upstream inputs into the Hippo pathway. Lastly, we will characterize novel regulators of Hippo signaling isolated from a sensitized screen for mutations that enhance a partial loss-of-Hippo phenotype in the eye. This unbiased approach will shed light on previously unforeseen regulators/mechanisms underlying the Hippo pathway. Besides revealing fundamental mechanisms of eye development, the proposed studies will have general implications for the development of other tissues.