Cell-cell interactions in drosophila development

多细胞生物体的发育需要单个细胞的承诺，以适当的细胞命运，然后他们随后的分化。Notch信号通路是参与确定从蠕虫到人类的生物体中细胞命运的关键通路之一。 这条通路的一个关键组成部分是神经化，我们多年前就发现了这一点。 在我们之前的NSERC资助过程中，我们发现Neuralized编码一种E3-泛素连接酶，该酶靶向Notch配体Delta，用于泛素介导的内化。 这提供了第一个证据，其配体的细胞内运输可以调节Notch途径。 我们还证明了Neuralized与磷酸肌醇结合，磷酸肌醇是介导膜运输和信号传导的膜脂质。 此外，我们发现神经化和磷酸肌醇之间的相互作用是Delta内化和Notch信号传导启动所必需的。本提案的目的是确定磷酸化是否可以调节Neuralized与磷酸肌醇的相互作用。 我们还将确定神经化和磷酸肌醇之间的相互作用是否是Notch信号传导的其他方面所必需的。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，以及这些是否是其他发育过程所必需的。这些研究将有助于我们阐明Neuralized在细胞命运决定中的功能及其与已知信号通路的关系，这些信号通路在发育过程中调节细胞-细胞相互作用方面非常重要。 由于Neuralized和Notch途径是高度保守的，因此了解这些基因在果蝇中的功能也将有助于了解大多数多细胞生物中细胞命运的获得方式。 最后，了解发育中调节细胞-细胞相互作用的机制可能会提供对细胞命运决定和与人类疾病（如癌症）相关的细胞-细胞信号传导缺陷的见解。

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.