CELLULAR ASSEMBLY AND TRANSPORT OF THE IGE RECEPTOR

描述(调查人员摘要)：众所周知， 过敏反应的启动要求涉及到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 无论是IgE水平还是细胞表面FcERI水平都有可能 干预过敏反应的发病机制。细胞内 FcERI的组装和向质膜的运输是一个复杂的过程 到目前为止，这在很大程度上还没有被探索过。关键步骤的定义 组装和运输途径可能为阻断FcERI开辟新的可能性 表达，更广泛的目的是减轻过敏反应。我们会 初步探讨人FceRI的组装和运输特性 Alphagamma2受体。除了FceRI伽马链的关联外，还有两个 在FceRI ct链生物合成过程中发生的其他关键事件 影响具有转运功能的AG2受体的形成：(I) 糖苷酶介导内质网a-链核心低聚糖的加工； (Ii)特定内质网伴侣蛋白，如钙粘连蛋白，与 新生的Fceri a-Chain。我们将重点研究Calnexin在促进AG2中的作用 组装和细胞表面表达，基于初步结果， 似乎对细胞表面的表达水平产生了深远的影响。 这些研究将扩展到转基因四聚体的表达。 FceRI abg2受体，以及嗜酸性粒细胞和 嗜碱性细胞。FceRI abg2可能表现出内在的高表达表型 而不是AG2受体，可能来自于改进的β链依赖 特异性介导的细胞内组装、稳定性和转运特性 呃，陪护。初步研究表明，Calnexin与 FceRI是一个亚单位，预测这种关联只会通过N-连锁的 在ct链胞外域中发现的多聚糖。这项提议的另一个目标是 比较和定义了7个N-连接糖基化位点中每一个的作用 钙粘蛋白和其他内质网伴侣蛋白的结合及其对细胞的影响 表面表达。本节目的最终目标是进一步分析 截短的FceRI a链的细胞内转运特性， 仅缺少高水平表达的细胞质结构域序列 在没有y-链的情况下，在转基因细胞的表面。因此，我们 将首次确定g链独立于a链的特定 运输和急诊室质量控制特点。

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.