Survival Mechanisms for Apoptotic Caspase

描述(申请人提供)：自从近20年前caspase被发现以来，一直有关于凋亡性caspase的非凋亡作用的报道。也许最清晰的范例是caspase-8(Casp8)，尽管它对于触发外在的凋亡途径是必不可少的，但它也是某些细胞群体在发育过程中生存所必需的。例如，对小鼠的缺失研究表明，casp8、其接头FADD和其调节因子FLIPL可能推动淋巴细胞、心肌细胞和某些类型的上皮细胞的克隆性增殖/增殖或凋亡。这一提议寻求为在生存和死亡之间做出选择提供生化证据，同时也有可能揭示生存途径的下游目标。因此，我们提供了概念验证工具和知识，可以导致化合物的开发，从而在治疗上干扰癌症等增殖性疾病的生存/死亡轴。这项研究将剖析“进入增殖程序的细胞的存活在很大程度上取决于casp8酶的构象和有限数量的下游靶点的切割”这一最重要的假设。我们提出了三个相互关联的目标来检验这一假设 通过定义驱动生存事件的casp8酶的生化性质，定义这种酶的靶标，并了解casp8如何在特定的实验细胞环境中促进生存而不是凋亡。每个目标都可以独立完成，每个目标的结果将大大加深对casp8介导的细胞生存机制的了解。然而，当来自目标1(casp8特异性的基本机制)的数据与目标2(内源性促进生存的casp8靶标)耦合时，该项目的全部力量就实现了，并且目标1和2的结果被用于提供适当的实验范式来定义细胞在生存和凋亡之间的决定(目标3)。这一建议具有重要意义，因为它试图揭示casp8用来描述死亡生存的分子机制，成功的结果可能直接影响正在临床开发的蛋白质和小分子药理工具作为癌症治疗药物的选择。

DESCRIPTION (provided by applicant): Ever since the discovery of the caspases almost 20 years ago there have been reports of non-apoptotic roles for apoptotic caspases. Perhaps the clearest paradigm is caspase-8 (casp8), which although essential for triggering the extrinsic apoptotic pathway, is also required for the survival of certain cell populations during development. For example, deletion studies in mice reveal that casp8, its adapter FADD, and its regulator FLIPL may drive either clonal expansion/proliferation or apoptosis of lymphocytes, cardiomyocytes, and some epithelial cell types. This proposal seeks to provide biochemical evidence for the choice between survival and death, while also having the potential to reveal downstream targets of the survival pathway. Thus we provide proof-of-concept tools and knowledge that can lead to the development of compounds to interfere therapeutically in the survival/death axis of proliferative diseases such as cancer. The overarching hypothesis "The survival of cells entering the proliferation program that depends on casp8 activity relies criticaly on the conformation of the casp8 enzyme and cleavage of a limited number of downstream targets" will be dissected in this study. We propose three interlinked aims to test this hypothesis by defining the biochemical nature of the casp8 enzyme that drives the survival events, defining the targets of this enzyme, and understanding how casp8 promotes survival, and not apoptosis, in specific experimental cellular contexts. Each aim can be accomplished independently, and the outcome of each aim will substantially further knowledge of the mechanisms of cell survival mediated by casp8. However, the full power of this project is realized when the data from Aim 1 (fundamental mechanisms of casp8 specificity) is coupled to Aim 2 (endogenous pro-survival casp8 targets), and the outcomes of Aims 1 and 2 used to inform the appropriate experimental paradigms for defining the cell's decision between survival and apoptosis (Aim 3). This proposal is significant because it seeks to reveal the molecular mechanism used by casp8 to delineate survival from death, and a successful outcome may impact directly on the selection of protein and small molecule pharmacologic tools that are under clinical development as cancer therapeutics.