Functional Signaling Domains of Notch Ligands

Notch 配体的功能信号传导域

• 批准号: 9727951
• 负责人: Robert Fleming
• 金额: $ 35.11万
• 依托单位: University of Rochester
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-01-15 至 2001-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9727951&HistoricalAwards=false
• 关键词: Functional; Signaling; Domains; Notch; Ligands

Fleming, Robert J.. 9727951 During the development of multicellular organisms, single cellular receptors are often used at multiple developmental periods. The Notch gene family represents a highly conserved group of genes whose functions are required in organisms as diverse as nematodes and humans. Notch and Notch-related gene products function as cell membrane receptors for intercellular signaling events to coordinate cell fate decisions in a variety of tissues during development. Notch activity is regulated by membrane-bound ligands which, in Drosophila, are represented by the products of the genes Serrate (SER) and Delta (DL). SER-like and DL-like molecules have also been found to be conserved in the same species where Notch family genes are found. These ligands demonstrate distinct temporal and spatial expression patterns suggesting that they each regulate NOTCH in particular processes. Interestingly, both SER and DL can act to initiate NOTCH signaling and appear to have equivalent capabilities during some processes yet function distinctly in others. Because SER and DL can elicit distinct responses from the single NOTCH receptor and since NOTCH is central to many cell fate decisions, these studies will investigate the mechanisms by which specificity is generated by each ligand upon association with NOTCH. The proposed experimentation will examine the roles of specific protein domains within SER and DL that contribute to the ability of that ligand to activate NOTCH in different cellular environments. Mechanisms of ligand function will be determined by constructing mutations of extracellular or intracellular (IC) domains of each ligand and expressing the mutant molecules in vivo. By analyzing the properties of these chimeric molecules relative to normal SER and DL, specific functional properties produced by individual protein domains will be determined. Initially, studies will focus on possible parallel mechanisms between NOTCH ligands and TGF(-like molecules that require IC domains f or proper extracellular function. Preliminary studies in these areas suggest that SER molecules function cooperatively and may activate NOTCH as a dimer or other aggregated form during some aspects of NOTCH signaling. These findings suggest other areas of experimentation including molecular examination for SER cleavage products and functional interactions between extracellular region mutations and the IC domain. Other areas of investigation include the characterization of a unique cysteine-rich domain found only within the SER ligand and not in DL. The properties of this domain will be characterized by deleting it from SER and/or inserting it into DL and assessing the ability of these modified ligands to interact with and/or activate the NOTCH receptor in specific cellular environments. Taken together, these studies are expected to expand the understanding of NOTCH signal regulation and further clarify mechanisms by which receptors in general may serve to send multiple, discrete signals upon activation by theft identified ligands.

弗莱明（Robert J. Notch基因家族代表了一组高度保守的基因，其在像线虫和人类一样多样化的生物中需要其功能。 Notch和Notch相关的基因产物充当细胞膜受体的细胞膜受体，用于在发育过程中协调各种组织中的细胞命运决策。 Notch活性受膜结合的配体调节，在果蝇中，该配体由锯齿状（Ser）和Delta（DL）的产物表示。在发现Notch家族基因的同一物种中，还发现Ser样和DL样分子是保守的。这些配体显示出不同的时间和空间表达模式，表明它们每个人都在特定过程中调节缺口。有趣的是，SER和DL都可以发挥Notch信号传导，并且在某些过程中似乎具有等效功能，但在其他过程中显然起作用。 由于SER和DL可以从单个Notch受体中引起明显的反应，并且由于Notch对许多细胞命运决策至关重要，因此这些研究将研究每种配体与Notch相关时产生特异性的机制。提出的实验将检查SER和DL内特定蛋白质结构域在不同细胞环境中激活缺口的能力的特定蛋白质结构域的作用。配体功能的机制将通过构建每个配体的细胞外或细胞内（IC）结构域的突变并在体内表达突变分子。通过分析这些嵌合分子相对于正常SER和DL的特性，将确定由单个蛋白质结构域产生的特定功能特性。最初，研究将集中于缺口配体和TGF之间可能的平行机制（ - 需要IC结构域或适当细胞外功能的类似分子。这些区域的初步研究表明Ser分子在合作上起作用，可能会激活Notch，并且可能会激活Notch作为二聚体或其他效果的效果。在细胞外区域突变和其他研究区域之间，仅在SER配体中发现了独特的富含半胱氨酸的结构域，而不是在DL中进行的特性，将其删除SER和/或将其插入DL并评估这些修饰的群机的能力。对Notch信号调节的理解和进一步阐明的机制，通常通过盗窃被发现的配体激活后，可以通过这些机制发送多个离散信号。