SIGNAL TRANSDUCTION BY THE HIGH AFFINITY IGE RECPTOR

高亲和力IgE受体FcEpsilonRl(已发现)的交联性 肥大细胞和嗜碱性粒细胞)，是导致 免疫球蛋白依赖性脱颗粒和炎性介质的释放。这 是即刻过敏反应的触发者，因此是 一些特应性疾病的主要事件，如过敏 鼻炎和过敏性哮喘。磷脂酰肌醇(Pls)的水解， 由磷酸酶C(PLC)催化，与激活 这种受体被认为对FcepsilonRI- 刺激脱颗粒。利用大鼠嗜碱性白血病(RBL)细胞， 肥大细胞模拟，我们开发了一种新颖的、无细胞的、 细胞质耗竭系统，在其中研究其机制 FcEpsilonRI激活PLC。与经典方法制备的膜不同 也就是说，这些“RBL细胞幽灵”保持着一种功能关系 Ige受体的交联和PI的水解性。出乎意料的是， FcEpsilon RIi介导的PI水解率被5大大刺激(4-15倍 MM磷酸烯醇式丙酮酸(PEP)，这种效应在幽灵中持续存在 已经被细菌毒素渗透，允许小分子 分子。将使用RBL细胞幽灵系统来实现 目的如下：1)刻画RBL细胞幽灵系统 通透性和确定PEP是否在 FcEpsilonRI介导的PI水解酶的激活不依赖于其 再生三磷酸腺苷的能力；2)研究三磷酸腺苷对磷酸化的作用 水分子、磷脂和蛋白质 FcEpsilonR1介导的触发；3)扩大我们的初步证据 一种新的磷酸化水产物，峰“y”，在 FcepsilonR1介导的触发，以及4)检查可用的RBL变体 细胞系，用于特定缺陷的细胞 ATP依赖的PLC激活和/或PEP依赖的增强 依赖三磷酸腺苷的信号。 这些研究将确定ATP和PEP在IgE中的作用 受体介导的PLC激活和增加我们对PLC的认识 这种信号被传递的机制。这是因为 负责这种作用的分子(S)可能是FcepsilonRI所特有的， 这一信息有可能导致新的药理药物的出现。 用于预防即刻过敏反应。论 另一方面，如果PEP的作用最终被发现形成了 一种新的受体信号转导范例，需要 对于启动信号的聚合，这些发现可能具有 对我们理解T细胞和B细胞上的抗原受体有很大影响 细胞以及巨噬细胞上的FcGamma受体。

Cross-linkage of the high affinity receptor for IgE, FcEpsilonRl (found on mast cells and basophils), is the initial event leading to IgE-dependent degranulation and release of inflammatory mediators. This is the trigger for immediate hypersensitivity reactions and thus is the primary event underlying a number of atopic diseases such as allergic rhinitis and allergic asthma. Hydrolysis of phosphoinositides (Pls), catalyzed by phosphohpase C (PLC), is closely linked to activation of this receptor and is thought to contribute substantially to FcepsilonRI- stimulated degranulation. Using rat basophilic leukemia (RBL) cells, a mast cell analog, we have developed a novel, cell-free, cytoplasm-depleted system in which to study the mechanism whereby FcEpsilonRI activates PLC. Unlike membranes prepared by classical means, these "RBL cell ghosts" retain a functional relationship between IgE receptor cross-linkage and PI hydrolysis. Unexpectedly, FcEpsilonRImediated PI hydrolysis is greatly stimulated (4-15 fold) by 5 mM phosphoenolpyruvate (PEP) and this effect persists in ghosts that have been permeabilized by bacterial toxins to allow diffusion of small molecules. The RBL cell ghost system will be used to achieve the following aims: 1) characterize the RBL cell ghost system following permeabilization and determine if the role of PEP in FcEpsilonRI-mediated activation of PI hydrolysis is independent of its ability to regenerate ATP; 2) examine the role ATP to phosphorylate aqueous molecules, phospholipids, and proteins during FcEpsilonR1-mediated triggering; 3)enlarge our preliminary evidence that a novel phosphorylated aqueous product, peak "y", is generated during FcepsilonR1 -mediated triggering, and 4) examine available variant RBL cell lines for ones which are specifically deficient in the ATP-dependent activation of PLC and/or in the PEP-dependent enhancement of the ATP-dependent signal. These studies will define the role of ATP and PEP in IgE receptor-mediated activation of PLC and increase our understanding of the mechanism whereby this signal is transduced. In that the molecule(s) responsible for this effect may be specific for FcepsilonRI, this information has the potential to lead to novel pharmacologic agents for the prevention of immediate hypersensitivity reactions. On the other hand, if the role of PEP is eventually found to form the basis for a new paradigm of signal transduction for those receptors requiring aggregation for the initiation of a signal, these findings may have great impact on our understanding of antigen receptors on T cells and B cells as well as Fcgamma receptors on macrophages.