Structure-function analysis of the mouse Delta1 gene in vivo and in vitro

Notch信号传导是调节多种发育过程的关键。Notch基因编码作为Delta和Serrate蛋白受体的跨膜蛋白。这些相互作用由这些蛋白质的胞外结构域中的多个EGF样重复模块介导和调节。为了分析小鼠Notch配体Delta1（Dll 1）的特定EGF样重复序列对体内Notch信号传导结果的意义，我们产生了Dll 1的等位基因系列，其中8个EGF重复序列中的每一个都通过用甘氨酸替换保守的半胱氨酸残基而单独突变。这些突变显示出广泛的表型变异，表明DLL1中的单个EGF重复序列在体内Notch活化方面是不等同的。拟议的实验旨在定义受单个EGF重复突变影响的过程，以及DLL1变体在体内和体外与受体结合和活化的特性。本研究将提供DLL1的特定EGF样重复序列在小鼠胚胎发生过程中不同发育环境中的作用的见解，并确定DLL1介导Notch结合和激活的区域。

Notch signalling is pivotal for the regulation of multiple developmental processes. Notch genes encode transmembrane proteins that act as receptors for Delta and Serrate proteins. These interactions are mediated and modulated by multiple EGF-like repeat modules in the extracellular domains of these proteins. To analyze the significance of particular EGF-like repeats of the mouse Notch ligand Delta1 (Dll1) for the outcome of Notch signalling in vivo we have generated an allelic series of Dll1, in which each of the eight EGF repeats has been mutated individually by replacing conserved Cysteine residues by Glycine. These mutations show a broad spectrum of phenotypic variation, indicating that individual EGF repeats in DLL1 are not equivalent with respect to Notch activation in vivo. The proposed experiments aim at defining the processes affected by individual EGF repeat mutations, and the properties of DLL1 variants with respect to receptor binding and activation in vivo and in vitro. This study will provide insights into the role of particular EGF-like repeats of DLL1 in different developmental contexts during mouse embryogeneis and define regions of DLL1 mediating Notch binding and activation.