TOLL-LIKE RECEPTORS: ACTIVATORS OF INNATE IMMUNITY

描述：(改编自申请者摘要)Toll样受体(TLRs) 在苍蝇等不同物种中介导病原体的先天免疫识别 和人类。这项建议的目的是分析细胞内如何 TLR的信号域相互作用，以产生不同的 对细菌产品作出反应的促炎信号。我们演示了 以前，虽然TLR4细胞质尾部的二聚化是 足以诱导产生肿瘤坏死因子-α，胞浆二聚化 TLR2或TLR6的尾部不起作用。相比之下，分子的异二聚化 TLR2和TLR6胞质尾巴可诱导产生肿瘤坏死因子-α。因此，它的作用机制 二聚体诱导的信号在这两个受体对之间是不同的。我们 建议定位TLR4胞质结构域中介导 同源二聚体诱导的信号转导，并定位细胞质区域的元件 TLR2/6介导异源二聚体诱导的信号转导。生物学的 这两种信令的结果是不同的，而TLR4 同二聚体诱导趋化因子IP-LO，TLR2/6异二聚体不诱导。我们会 确定TLR4胞质结构域中特异性介导 IP-10的诱导，并识别与TLR4结合的信号分子 同源二聚体，而不是TLR2/6异源二聚体。尽管我们已经展示了 以前，TLR4介导巨噬细胞的内毒素反应，而TLR2/6 调节对肽聚糖的反应，有诱人的证据表明 在某些情况下，TLR2可能参与了内毒素诱导的反应。这样的一个 环境是IL-12的诱导；TLR2的一个显性负突变 特异性地消除这一反应，而不同的TLR2突变体不能。 有趣的是，两个突变体都没有阻断内毒素诱导的肿瘤坏死因子-a。这种区别应该是 允许我们绘制TLR2细胞质结构域的不同区域 参与内毒素诱导的IL-12的产生。我们使用了一种快速而健壮的 一种定位TLR胞质结构域信号容量的方法 2、4和6二聚体，我们将扩展这些研究以检查 所有10个TLR的细胞质结构域都能产生促炎信号。 因此，该提案将定义不同对的信令曲目 以及这些分子的细胞质结构域的区域 负责触发不同的反应，如导致肿瘤坏死因子-Cz的反应， IP-LO和IL-12。

DESCRIPTION: (Adapted from applicant's abstract) The Toll-like receptors (TLRs) mediate innate immune recognition of pathogens in species as diverse as flies and humans. The purpose of this proposal is to analyze how the intracellular signaling domains of TLRs interact with each other to generate distinct pro-inflammatory signals in response to bacterial products. We demonstrated previously that while dimerization of the cytoplasmic tail of TLR4 is sufficient to induce the production of TNF-a, dimerization of the cytoplasmic tails of either TLR2 or TLR6 does not. In contrast, heterodimerization of the cytoplasmic tails of TLR2 and TLR6 does induce TNF-a. Thus, the mechanism of dimer-induced signaling is different between these two receptor pairs. We propose to map the elements of the cytoplasmic domain of TLR4 that mediate homodimer-induced signaling, and to map the elements of the cytoplasmic domains of TLR2/6 that mediate heterodimer-induced signaling. The biological consequences of these two types of signaling are different; while TLR4 homodimers induce the chemokine IP-lO, TLR2/6 heterodimers do not. We will define the regions of the cytoplasmic domain of TLR4 that specifically mediate the induction of IP- 10, and identify signaling molecules that bind to TLR4 homodimers, and not to TLR2/6 heterodimers. Although we have demonstrated previously that TLR4 mediates LPS-responses in macrophages, while TLR2/6 mediates responses to peptidoglycan, there is tantalizing evidence that under certain circumstances, TLR2 may participate in LPS-induced responses. One such circumstance is the induction of IL-12; one dominant negative mutant of TLR2 specifically ablates this response while a distinct TLR2 mutant does not. Interestingly, neither mutant blocks LPS-induced TNF-a. This distinction should permit us to map distinct areas of the cytoplasmic domain of TLR2 that participate in LPS-induced IL-12 production. We have used a rapid and robust method for mapping the signaling capacity of the cytoplasmic domains of TLR 2,4, and 6 dimers, and we will extend these studies to examine the capacity of the cytoplasmic domains of all ten TLRS to generate pro-inflammatory signals. This proposal will therefore define the signaling repertoire of different pairs of TLRs, as well as the regions of the cytoplasmic domains of these molecules responsible for triggering distinct responses such as those leading to TNF-cz, IP-lO, and IL-12.