CELLULAR ASSEMBLY AND TRANSPORT OF THE IGE RECEPTOR

描述（研究者摘要）：已明确， 过敏反应的起始需要涉及IgE的相互作用， 其高亲和力受体（FceRI）在造血细胞上表达。 通过操纵表达来调节这种相互作用的努力 IgE或细胞表面FcERI的水平将提供 干预过敏反应的发病机制。细胞内 FcERI向质膜的组装和转运是一个复杂的过程 迄今为止还未被探索过关键步骤的定义 组装和转运途径可以为阻断FcERI开辟新的可能性 表达具有减弱过敏反应的更广泛目的。我们将 初步探索人FceRI的组装和转运特性 γ 2受体。除了FceRI γ链的缔合之外，两个 在FceRI α链生物合成期间发生的其它关键事件 影响有运输能力的Ag 2受体的形成：（i） 内质网中α-链核心寡糖的糖苷酶介导的加工; (ii)特异性ER分子伴侣，如钙连接蛋白， 新生FceRI α链。我们将重点关注钙连接蛋白在促进ag 2 组装和细胞表面表达，基于初步结果， 似乎对细胞表面表达水平产生深远的影响。 这些研究将扩展到转染的四聚体的表达。 FceRI abg 2受体，以及嗜酸性粒细胞和 嗜碱性粒细胞FceRI abg 2可能表现出固有的更高表达表型 比ag 2受体，可能来自改善，β-链依赖 细胞内组装、稳定性和转运特性 急诊监护人最初的研究表明，钙连接蛋白与 FceRI a亚基，预测仅通过N-连接的 在Ct-链胞外域中发现的聚糖。本提案的另一个目标是 比较并定义了7个N-连接糖基化位点中每一个的作用， 与钙连接蛋白和其它内质网伴侣蛋白的结合及其对细胞的作用 表面表达本计划的最后一个目标是进一步分析 截短的FceRI α链的细胞内转运特征， 仅缺乏高水平表达的胞质结构域序列 在不存在Y链的转染细胞的表面上。因此我们 将首次确定g链独立的a链特异性 运输和ER质量控制特性。

DESCRIPTION (investigator's abstract): It is well established that the initiating requirement of the allergic response involves the interaction of IgE with its high affinity receptor (FceRI) expressed on hematopoietic cells. Efforts to modulate this interaction through manipulation of the expression levels of either IgE or cell surface FcERI would offer the potential to intervene in the pathogenesis of the allergic response. The intracellular assembly and transport of FcERI to the plasma membrane is a complex process that has thus far been largely unexplored. Definition of critical steps in the assembly and transport pathway could open new possibilities in blocking FcERI expression with the broader aim of attenuating the allergic response. We will initially explore the assembly and transport characteristics of the human FceRI alphagamma2 receptor. In addition to association of the FceRI gamma-chain, two other critical events occur during FceRI ct-chain biosynthesis that profoundly influence the formation of a transport competent ag2 receptor: (i) glycosidase-mediated processing of a-chain core oligosaccharides in the ER and; (ii) the association of specific ER chaperones, such as calnexin, with the nascent FceRI a-chain. We will focus on the role of calnexin in promoting ag2 assembly and cell surface expression which, based on preliminary results, appears to exert a profound effect on the level of cell surface expression. These studies will then be extended to expression of transfected tetrameric FceRI abg2 receptor, as well as constitutive receptor in eosinophils and basophils. FceRI abg2 may exhibit an intrinsically higher expression phenotype than the ag2 receptor, possibly derived from improved, beta-chain-dependent intracellular assembly, stability and transport properties mediated by specific ER chaperones. Initial studies have revealed that calnexin associates with the FceRI a subunit, an association predicted to occur exclusively via the N-linked glycans found in the ct-chain ectodomain. A further goal of this proposal is compare and defined the role of each of the 7 N-linked glycosylation sites in association with calnexin and other ER chaperone and their effect on cell surface expression. A final objective in this program is the further analysis of intracellular transport characteristics of a truncated FceRI a-chain, lacking only the cytoplasmic domain sequence, which expresses at a high level on the surface of transfected cells in the absence of the y-chain. Thus we will, for the first time, determine g-chain independent a-chain-specific transport and ER quality control characteristics.