STRUCTURE AND FUNCTION OF THE LYMPHOCYTE FCE RECEPTOR

描述(调查者摘要)：这是一个续集 在分子调控、结构和功能研究中的应用 低亲和力IgE受体(Fc-epsilon-RII)，使用小鼠系统。 总体目标是进一步深入了解这一角色 分子在即刻超敏反应和B细胞激活中发挥作用 和差异化。目标1：IL-4的分子机制 将确定诱导的Fc-epsilon-RII上调。推动者 小鼠Fc-epsilon-RII基因的区域已初步确定 使用CAT报告质粒进行鉴定。这将得到进一步的定义 有更多的缺失研究和对IL-4有反应的区域 将会被确定。然后，将通过以下方式进一步探讨该机制 可能与IL-4相互作用的DNA结合蛋白的分析 响应元素。最后，信使核糖核酸稳定所起的作用 在IL-4诱导的Fc-epsilon-RII调节中也会 下定决心。在目标2中，Fc-epsilon-RII结构是 将确定IGE绑定。目前的结果表明，FC- Epsilon-RII形成类似于其他“盘绕线圈”的三聚体结构 原肌球蛋白等分子。负责这种受体的区域- 受体的相互作用已经被确定；它被称为“茎”。 Fc-epsilon-RII的区域。额外缺失突变体Fc-epsilon-RII 以及嵌合Fc-epsilon-RII，其中凝集素同源 地区是依附于另一个C型家庭的“梗”将准备好 并对IgE结合和寡聚体形成进行了分析。各种新的 SFC-epsilon-RII的生物学活性已在 人。在目标3中，制备了可溶性Fc-epsilon-RII结构 在目标2中，将对生物活动进行分析。证监会- Epsilon-RII结构将被测试对肥大细胞的活性 关于介质和细胞因子的释放与B细胞 协同刺激、免疫球蛋白E的产生和抑制突起。 这些研究还将允许确定一种配体是否 除IgE外，Fc-epsilon-RII还存在。两种生物活动 对于完整的Fc-epsilon-RII已经在当前的 授权期--加强抗原呈递和修饰 抗-Ig介导的B细胞活化。利用突变体Fc-epsilon-RII 在目标数2中产生的分子，容量之间的关联 低聚物的形成和生物活性将被确定。 此外，这些突变体以及缺少 细胞质尾巴的调节能力将被检查 内化和细胞骨架联合。最后，由于这些 发现表明免疫球蛋白E复合体的新作用，体内的影响 将检测Fc-epsilon-RII对该表型的靶向性。

DESCRIPTION (Investigator's Abstract): This is a continuation application to study the molecular regulation, structure and function of the low affinity IgE receptor (Fc-epsilon-RII), using the mouse system. The overall aim is to gain further insight into the roles this molecule plays in immediate hypersensitivity and in B-cell activation and differentiation. In aim number 1 the molecular mechanism of IL-4 induced Fc-epsilon-RII up-regulation will be determined. The promoter region of the murine Fc-epsilon-RII gene has been tentatively identified using CAT reporter plasmids. This will be further defined with additional deletion studies and the region that responds to IL-4 will be determined. The mechanism will then be further explored by analysis of DNA-binding proteins that may interact with the IL-4 responsive element. Finally, the role that mRNA stabilization plays in the IL-4- induced Fc-epsilon-RII regulation will also be determined. In aim number 2, the Fc-epsilon-RII structure necessary for IgE binding will be determined. Current results indicate that the Fc- epsilon-RII forms a trimeric structure analogous to other "coiled-coil" molecules such as tropomyosin. The region responsible for this receptor- receptor interaction has been identified; it is termed the "stalk" region of the Fc-epsilon-RII. Additional deletion mutant Fc-epsilon-RII as well as chimeric Fc-epsilon-RII in which the lectin homologous region is attached to the other C-type family "stalk" will be prepared and analyzed for IgE- binding and oligomer formation. A variety of new biologic activities for the sFc-epsilon-RII have been described in humans.In aim number 3 the soluble Fc-epsilon-RII constructs prepared in aim number 2 will be analyzed for biologic activity. The sFc- epsilon-RII constructs will be tested for activity against mast cells with respect to mediator and cytokine release and B-cells with respect to costimulation, IgE production and inhibition of a proptosis. These studies will also allow the determination of whether a ligand other than IgE exists for the Fc-epsilon-RII. Two biologic activities for the intact Fc-epsilon-RII have been identified in the current grant period--enhancement of antigen presentation and modification of anti-Ig mediated B-cell activation. Using the mutant Fc-epsilon-RII molecules produced in aim number 2, the correlation between capacity for oligomer formation and biologic activity will be determined.In addition, these mutants, as well as a mutant Fc-epsilon-RII lacking a cytoplasmic tail will be examined for the capacity to modulate internalization and cytoskeletal association. Finally, as these findings indicate new roles for IgE complexes, the effect of in vivo targeting the Fc-epsilon-RII on TH phenotype will be assayed.