Cell-cell interactions in drosophila development

多细胞生物的发育需要单个细胞承担适当的细胞命运，然后再进行分化。在从蠕虫到人类的各种生物中，决定细胞命运的关键途径之一是Notch信号通路。这个通路的一个关键组成部分是神经化，我们很多年前就发现了。在我们之前的NSERC资助过程中，我们表明Neuralized编码e3 -泛素连接酶，该连接酶靶向Notch配体Delta，用于泛素介导的内化。这提供了细胞内转运其配体可以调节Notch通路的第一个证据。我们还证明了Neuralized与磷酸肌苷、膜脂结合，介导膜运输和信号传导。此外，我们发现神经化和磷酸肌苷之间的相互作用是Delta内化和Notch信号启动所必需的。本研究的目的是确定磷酸化是否可以调节神经化与磷酸肌苷的相互作用。我们还将确定Notch信号的其他方面是否需要神经化和磷酸肌苷之间的相互作用。最后，我们将确定蛋白质-蛋白质相互作用如何影响Neuralized结合和内吞Delta的能力，以及这些是否为其他发育过程所必需。这些研究将有助于我们阐明神经化在细胞命运决定中的功能及其与发育过程中调节细胞-细胞相互作用的已知信号通路的关系。由于Neuralized和Notch通路是高度保守的，了解果蝇中这些基因的功能也将揭示大多数多细胞生物中细胞命运获得的方式。最后，了解发育过程中调节细胞-细胞相互作用的机制可能有助于深入了解与人类疾病（如癌症）相关的细胞命运决定和细胞-细胞信号传导缺陷。

The development of a multicellular organism requires the commitment of individual cells to the appropriate cell fate and then their subsequent differentiation. One of the key pathways involved in specifying cell fates in organisms as diverse as worms to man, is the Notch signaling pathway. A key component of this pathway is Neuralized, which we identified many years ago. During the course of our previous NSERC grant, we showed that Neuralized encodes an E3-ubiquitin ligase that targets the Notch ligand, Delta, for ubiquitin-mediated internalization. This provided the first evidence that intracellular trafficking of its ligands could regulate the Notch pathway. We also demonstrated that Neuralized binds to phosphoinositides, membrane lipids that mediate membrane trafficking and signaling. Moreover, we showed that the interaction between Neuralized and phosphoinositides was required for Delta internalization and the initiation of Notch signaling. The goal of the present proposal is to determine if phosphorylation can regulate the interaction of Neuralized with phosphoinositides. We will also determine if the interaction between Neuralized and phosphoinositides is required for other aspects of Notch signaling. Finally, we will determine how protein-protein interactions affect the ability of Neuralized to bind and endocytose Delta and whether these are required for other developmental processes. These studies will help us to elucidate the function of Neuralized in cell fate decisions and its relationship to known signaling pathways important in regulating cell-cell interactions during development. Since Neuralized and the Notch pathway are highly conserved, understanding the function of these genes in Drosophila will also shed light onto ways that cell fates are acquired in most multicellular organisms. Finally, understanding the mechanisms regulating cell-cell interactions in development may provide insights into defects in cell fate decisions and in cell-cell signaling associated with human diseases such as cancer.