Mechanisms of NF-kappaB Activation in T Lymphocytes

T 淋巴细胞中 NF-κB 激活的机制

• 批准号: 6809541
• 负责人: Zhijian J Chen
• 金额: $ 35.1万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-06-01 至 2009-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6809541
• 关键词: I kappa B beta; RNA interference; T cell receptor; T lymphocyte; biological signal transduction; cell free system; cell proliferation; enzyme activity; enzyme complex; gene expression; immune response; leukocyte activation /transformation; ligase; lipids; nuclear factor kappa beta; peptidases; phosphorylation; protein kinase C; protein protein interaction; protein structure function; receptor expression; recombinant proteins; transfection; ubiquitin

DESCRIPTION (provided by applicant): NF-KappaB plays a pivotal role in the activation of T lymphocytes during immune responses. Upon engagement of T cell receptor (TCR) with a foreign antigen, a signal transduction cascade is activated, culminating in the activation of NFKB, which controls the expression of genes essential for the proliferation and function of T cells. While much is known about the pathways of NF-KB activation by proinflammatory cytokines, the mechanism by which NF-kappaB is activated by TCR is not well understood. A key regulator of NF-KappaB pathway is the IKappaB kinase (IKK) complex, which phosphorylates the NF-kappaB inhibitor IKappaB and targets this inhibitor for degradation by the ubiquitin-proteasome pathway, thus allowing NF-KappaB to enter the nucleus to control gene expression. BCL10, a CARD domain protein implicated in MALT lymphoma, has recently been shown to play an essential role in IKK activation by TCR in T lymphocytes. However, BCLI0 does not activate IKK directly, leaving a large gap in our understanding of the signaling pathways downstream of TCR. The major goal of this proposal is to understand how BCL10 is linked to IKK on the one hand, and to TCR on the other hand. In an effort to understand how BCL10 activates IKK, we have established a cell free system that activates IKK in response to addition of BCL10 protein. Fractionation of cell extracts led to the identification of several proteins operationally defined as IKABs (IKK Activators downstream of BCL10) that mediate IKK activation by BCL10 in vitro. Significantly, we find that IKK in T cells is activated by BCL10 through a ubiquitin-dependent but proteasome-independent mechanism. These results suggest that ubiquitination plays a regulatory role not only in innate immunity, but also in adaptive immunity. Our next step is to determine whether and how IKABs are involved in IKK activation in T lymphocytes (Aim 1). We will also investigate the mechanisms by which BCL10 activates IKABs (Aim 2). Finally, we will study how BCL10 is regulated by upstream signaling molecules in the TCR pathway (Aim 3). Collectively, these lines of investigation should lead to a better understanding of the NF-KappaB signaling pathways in T cells. Such knowledge is crucial to understanding and treating various human diseases, including MALT lymphoma and other immune disorders.

描述（由申请人提供）： NF-KappaB 在免疫反应过程中 T 淋巴细胞的激活中发挥着关键作用。 T 细胞受体 (TCR) 与外源抗原结合后，信号转导级联被激活，最终激活 NFKB，NFKB 控制 T 细胞增殖和功能所必需的基因表达。虽然人们对促炎细胞因子激活 NF-κB 的途径了解很多，但 TCR 激活 NF-κB 的机制尚不清楚。 NF-KappaB 通路的关键调节因子是 IKappaB 激酶 (IKK) 复合物，它磷酸化 NF-kappaB 抑制剂 IKappaB，并通过泛素-蛋白酶体通路靶向该抑制剂进行降解，从而使 NF-KappaB 进入细胞核来控制基因表达。 BCL10 是一种与 MALT 淋巴瘤有关的 CARD 结构域蛋白，最近被证明在 T 淋巴细胞中 TCR 激活 IKK 中发挥重要作用。然而，BCLI0并不直接激活IKK，这使得我们对TCR下游信号通路的理解存在很大差距。该提案的主要目标是了解 BCL10 如何一方面与 IKK 关联，另一方面与 TCR 关联。为了了解 BCL10 如何激活 IKK，我们建立了一个无细胞系统，该系统响应 BCL10 蛋白的添加而激活 IKK。细胞提取物的分级分离鉴定了几种在操作上被定义为 IKAB（BCL10 下游的 IKK 激活剂）的蛋白质，它们在体外介导 BCL10 介导 IKK 激活。值得注意的是，我们发现 T 细胞中的 IKK 被 BCL10 通过泛素依赖但不依赖于蛋白酶体的机制激活。这些结果表明泛素化不仅在先天免疫中发挥调节作用，而且在适应性免疫中也发挥调节作用。我们的下一步是确定 IKAB 是否以及如何参与 T 淋巴细胞中的 IKK 激活（目标 1）。我们还将研究 BCL10 激活 IKAB 的机制（目标 2）。最后，我们将研究 BCL10 如何受到 TCR 通路中上游信号分子的调节（目标 3）。总的来说，这些研究方向应该有助于更好地理解 T 细胞中的 NF-KappaB 信号通路。这些知识对于理解和治疗各种人类疾病至关重要，包括 MALT 淋巴瘤和其他免疫性疾病。