Regulation of TNF-alpha by Integrin-Mediated Matrix Signaling

描述（由申请人提供）：肿瘤坏死因子（TNF）家族的细胞因子在炎症、宿主防御和免疫的调节中发挥关键作用，并能以细胞类型和环境依赖的方式诱导程序性细胞死亡。TNFa是NFicB的有效激活剂，可导致多种抗凋亡和促炎因子的合成。因此，只有当NFicB信号或新生蛋白合成被阻断时，TNFa才能在大多数细胞类型中诱导细胞凋亡，而它如何在体内触发细胞凋亡尚不清楚。最近，我们已经证明，适当的细胞外基质环境可以覆盖NFicB的促生存作用，使TNFa诱导细胞凋亡，而不会干扰nfxb诱导的转录或cfe - novo蛋白合成。基质蛋白CCN1 （CYR61）、CCN2 （CTGF）或CCN3 （NOV）的存在使TNFa能够诱导原本耐药的原代人成纤维细胞凋亡。CCN1通过结合整合素avf35> aepi和硫酸肝素蛋白聚糖syndecan-4与TNFa协同作用，导致凋亡所需的活性氧（ROS）依赖的JNK双相激活。此外，基因组Ccn1位点被凋亡缺陷Ccn1等位基因取代的小鼠在TNFa诱导的凋亡中严重钝化，表明Ccn1 /TNFa协同作用是体内重要的凋亡途径。因此，细胞外基质微环境可以深刻调节TNFa的凋亡活性，并决定TNFa是执行促生还是促死程序。在本应用中，我们提出在三个特定目的中研究TNFa和CCN1之间的凋亡相互作用：1。阐明多个CCN1受体如何相互作用；2. 分析TNFa-和ccn1诱导的信号通路如何汇聚；和3。研究TNFa-CCN1相互作用在体内的生理意义。我们预计这些研究将产生关于TNF细胞因子的活性如何被细胞外基质调节的重要新信息，并揭示TNF在其中发挥作用的许多疾病过程。

DESCRIPTION (provided by applicant): Cytokines of the tumor necrosis factor (TNF) family play critical roles in the regulation of inflammation, host defense and immunity, and can induce programmed cell death in a cell type- and context-dependent manner. TNFa is a potent activator of NFicB, which leads to the synthesis of multiple anti-apoptotic and proinflammatory factors. Consequently, TNFa induces apoptosis in most cell types only when NFicB signaling or de novo protein synthesis is blocked, and how it triggers apoptosis in vivo is not well understood. Recently, we have shown that the appropriate extracellular matrix environment can override the pro-survival effects of NFicB, enabling TNFa to induce apoptosis without perturbation of either NFxB-induced transcription or cfe novo protein synthesis. The presence of the matrix proteins CCN1 (CYR61), CCN2 (CTGF), or CCN3 (NOV) enables TNFa to induce apoptosis in the otherwise resistant primary human fibroblasts. CCN1 synergizes with TNFa through binding to integrins avf35> aepi and the heparan sulfate proteoglycan syndecan-4, leading to the reactive oxygen species (ROS)-dependent biphasic activation of JNK necessary for apoptosis. Furthermore, mice with the genomic Ccn1 locus replaced with an apoptosis-defective Ccn1 allele are severely blunted in TNFa-induced apoptosis, indicating that CCN1/TNFa synergism is an important apoptotic pathway in vivo. Thus, the extracellular matrix microenvironment can profoundly regulate the apoptotic activity of TNFa, and dictate whether TNFa executes a pro-life or pro-death program. In this application, we propose to investigate this apoptotic interaction between TNFa and CCN1 in three specific aims: 1. to elucidate how the multiple CCN1 receptors interact; 2. to analyze how TNFa- and CCN1-induced signaling pathways converge; and 3. to examine the physiological significance of TNFa-CCN1 interactions in vivo. We anticipate that these studies will yield important new information on how the activities of TNF cytokines can be contextually regulated by the extracellular matrix, and shed light on the many disease processes in which TNFa plays a role.