Imaging Delta-Induced Activation of Notch

描述（由申请人提供）：Notch信号是一种高度保守的细胞通信系统，在整个发育过程和成年期调节多种细胞类型。Notch信号转导的缺陷与许多人类疾病状态有关，包括癌症、中风和阿尔茨海默病，这强调了理解Notch信号转导的基本机制的重要性。细胞表面Notch受体与细胞表面配体结合后，经历一系列蛋白水解裂解事件，释放细胞内Notch结构域。这个蛋白水解片段易位到信号接收细胞的细胞核，在那里它直接调节Notch靶基因的转录。基于对果蝇的研究，提出了一个Notch信号传导的模型，其中配体信号传导细胞在配体呈递之外的Notch激活中发挥积极作用。这些模型表明，在信号转导过程中，配体细胞通过尚不清楚的反式内吞作用现象主动去除Notch细胞外结构域。本研究旨在确定哺乳动物中反式内吞作用是否是配体诱导的Notch信号的一个特征。为此，开发了一种可以用共聚焦显微镜检查的共培养系统。这种共培养模式将允许表征Notch向δ细胞转移的具体情况，提供对反式内吞作用的分子机制及其与Notch信号传导的相关性的深入了解。

DESCRIPTION (provided by applicant): Notch signaling is a highly conserved cell communication system that regulates a wide variety of cell types throughout development and into adulthood. Defects in Notch signal transduction have been implicated in a number of human disease states including cancer, stroke, and Alzheimer's disease, underscoring the importance of understanding the basic mechanisms of Notch signal transduction. Cell-surface Notch receptors, following engagement with cell-surface ligands, undergo a series of proteolytic cleavage events which release the intracellular domain of Notch. This proteolytic fragment translocates to the nucleus of the signal receiving cell where it directly regulates transcription of Notch target genes. Based on studies in Drosophila, a model for Notch signaling has been proposed in which the ligand-signaling cell plays an active role in Notch activation beyond ligand presentation. These models propose that during signal transduction the ligand cell actively removes the Notch extracellular domain through the poorly understood phenomenon of trans-endocytosis. This proposal aims to determine if trans-endocytosis is a characteristic of ligand- induced Notch signaling in mammals. To this end, a coculture system that can be examined by confocal microscopy has been developed. This coculture paradigm will allow characterization of the specifics of Notch transfer to Delta cells, providing insight into the molecular mechanism of trans-endocytosis and its relevance to Notch signaling.