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、宿主防御和免疫调节中发挥关键作用，并能以细胞类型和环境依赖性方式诱导程序性细胞死亡。TNF α是NF κ B的有效激活剂，其导致多种抗凋亡和促炎因子的合成。因此，只有当NF κ B信号传导或从头蛋白质合成被阻断时，TNF α才在大多数细胞类型中诱导凋亡，并且其如何在体内触发凋亡还没有很好地理解。最近，我们已经表明，适当的细胞外基质环境可以覆盖NFxB的促存活作用，使得TNF α能够诱导凋亡，而不干扰NFxB诱导的转录或新生蛋白质合成。基质蛋白CCN 1（CYR 61）、CCN 2（CTGF）或CCN 3（NOV）的存在使得TNF α能够在其他抗性原代人成纤维细胞中诱导凋亡。CCN 1通过结合整联蛋白avf 35、aepi和硫酸乙酰肝素蛋白聚糖多配体蛋白聚糖-4与TNF α协同作用，导致细胞凋亡所必需的JNK的活性氧（ROS）依赖性双相活化。此外，基因组Ccn 1基因座替换为肿瘤坏死因子缺陷型Ccn 1等位基因的小鼠在TNF α诱导的细胞凋亡中严重钝化，表明CCN 1/TNF α协同作用是体内重要的细胞凋亡途径。因此，细胞外基质微环境可以深刻地调节TNF α的凋亡活性，并决定TNF α是否执行促生命或促死亡程序。在本申请中，我们提出在三个特定目的中研究TNF α和CCN 1之间的这种凋亡相互作用：1.阐明多种CCN 1受体如何相互作用; 2.分析TNFa和CCN 1诱导的信号通路如何会聚;以及3.以检查体内TNFa-CCN 1相互作用的生理学意义。我们预计，这些研究将产生重要的新信息，TNF细胞因子的活动如何可以上下文调节的细胞外基质，并阐明了许多疾病的过程中，TNF α发挥作用。

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.