Regulation of TNF Receptor-Mediated Apoptosis

描述（由申请人提供）：TNF特异性拮抗剂治疗类风湿性关节炎（RA）的临床疗效表明TNF在RA发病机制中的关键作用。TNF与其受体之一TNF受体1（TNFR 1）的结合可激活NF-κ B转录因子，导致基因表达或导致细胞凋亡的半胱天冬酶途径。最近的研究表明，NF-κ B诱导抗凋亡基因的表达，然后拮抗同时激活的凋亡途径。因此，一个重要的问题是什么样的抗凋亡基因的NF-κ B的调节和他们如何抑制细胞凋亡。一个Jurkat T细胞突变体，是在IKK /NEMO缺陷，一个NF-kB信号通路的必要组成部分，已被分离，作为这种缺陷的结果，这种突变体表现出显着增加的敏感性TNF诱导的细胞凋亡。A20是NP-B调节基因，通过阻断RIP（TNF途径中的死亡结构域激酶）或RIP上游分子，有效阻断突变细胞中TNF诱导的凋亡。在特定目标1中，A20的精确分子靶点将通过上位性分期研究，结合基于我们目前对近端TNFR 1信号转导的理解而制定的假设检验来定义。在具体目标2中，将通过鉴定与A20相互作用的蛋白质来检查A20所利用的机制。所使用的方法将基于A20与其配偶体之间的从头相互作用，其可以通过抗A20抗体分离。随后将采用一些办法来确定相关伙伴。在特异性Aim 3中，将在该突变细胞系中搜索不再被TNF上调的基因，然后对其破坏细胞凋亡途径的能力进行功能测试。该项目的最终结果将是对TNF调控的途径和下游基因有更深入的了解，这可能为RA的药理学调节提供了额外的途径。

DESCRIPTION (provided by applicant): The clinical efficacy of TNF-specific antagonists in the treatment of rheumatoid arthritis (RA) points to the critical role of TNF in RA pathogenesis. Binding of TNF to one of its receptors, TNF receptor 1 (TNFR1) can activate NF-kB transcription factors leading to gene expression or the caspase pathway leading to apoptosis. Recent studies have shown that NF-kB induces the expression of anti-apoptotic genes, which then antagonize the apoptosis pathway that is concurrently activated. Therefore, an important question is what are the anti-apoptotic genes regulated by NF-kB and how do they inhibit apoptosis. A Jurkat T cell mutant that is deficient in IKK /NEMO, an essential component of the NF-kB signaling pathway, has been isolated and as a result of this deficiency, this mutant exhibits a profound increase in sensitivity to TNF-induced apoptosis. A20, a NP- B-regulated gene, effectively blocks TNF-induced apoptosis in the mutant cell by blocking either RIP, a death domain kinase in the TNF pathway, or a molecule upstream of RIP. In Specific Aim 1, the precise molecular target of A20 will be defined by epistasis staging studies, combined with the testing of hypothesis that were formulated based on our current understanding of proximal TNFR1 signal transduction. In Specific Aim 2, the mechanism utilized by A20 will be examined by identifying proteins that interact with A20. The approaches used will be based on the de novo interaction between A20 with its partners, which can be isolated by anti-A20 antibodies. A number of schemes will be used subsequently to identify the associated partners. In Specific Aim3, a search for genes that are no longer upregulated by TNF in this mutant cell line will be conducted and then functionally tested for their ability to disrupt the apoptosis pathway. The end result of this project will be a greater knowledge of the pathways and downstream genes regulated by TNF, which may suggest additional avenues for pharmacological modulation in RA.