蛋白4.1R对肥大细胞脱颗粒调控的分子机制

The activation and degranulation of mast cell are important in the progression of allergic disease, but modulators involving in this process are largly unknown. Protein 4.1R was first identified as a membrane cytoskeleton protein in red cells, but in our recent study 4.1R gene knockout was found to enhance the degranulation of BMMC. Moreover, evidences also showed that 4.1R was involved in the antigen-specific activation of BMMC mediated by IgE, but no mechanism reports of 4.1R in modulating activation and degranulation of mast cells were available. Based on the discovery in our previous study, 4.1R gene knockout mice 4.1R-/-C57BL/6J and 4.1R-/-BMMC are used to investigate the immune effects of 4.1R in degranulation of mast cells and the associated diseases, as well as the modulation effects on signaling transduction initiated by FcεRI. This functional and mechanistic study of protein 4.1R in activation and degranulation of mast cells will support the hypothesis that protein 4.1R is a novel regulator of mast cell activation and degranulation.

肥大细胞活化及脱颗粒是变态反应性疾病发生的关键环节，然而参与肥大细胞活化调控的分子目前还未被完全了解。蛋白4.1R最初是在红细胞中发现的细胞膜骨架蛋白分子，我们在前期研究中发现4.1R基因敲除显著增强小鼠骨髓来源的肥大细胞BMMC脱颗粒能力，且初步证实4.1R参与抗原特异性IgE介导的BMMC活化，但4.1R对肥大细胞活化及脱颗粒的调控作用及分子机制尚不清楚。本项目拟利用基因敲除小鼠4.1R-/-C57BL/6J和4.1R-/-BMMC，研究4.1R在 肥大细胞脱颗粒及相关疾病中的免疫生理效应，并探讨4.1R基因缺失对FcERI启动的肥大细胞信号转导的影响，以期阐明4.1R在肥大细胞活化与脱颗粒过程中发挥的生物学功能及可能的分子机制，为证实细胞骨架蛋白4.1R是又一新发现的肥大细胞活化及信号转导的调控因子提供实验依据。

红细胞膜骨架蛋白4.1R在小鼠骨髓来源的肥大细胞（BMMCs）中高表达，但功能未知。项目利用4.1R表达缺失C57BL/6J-4.1R-/-小鼠模型和4.1R表达缺失骨髓来源肥大细胞BMMC-4.1R-/-模型，从分子、细胞和动物整体水平研究了蛋白4.1R在肥大细胞活化及信号转导中的生物学功能。通过比较BMMC-4.1R+/+ 和BMMC-4.1R-/-在IgE 介导的肥大细胞脱颗粒、细胞因子及趋化因子合成分泌等表型，结果发现4.1R表达缺失导致肥大细胞脱颗粒和细胞因子合成增强，提示蛋白4.1R对肥大细胞活化发挥负调控作用；通过比较C57BL/6J-4.1R+/+和C57BL/6J-4.1R-/-小鼠被动皮肤过敏和哮喘模型的疾病表型差异，发现4.1R表达缺失导致小鼠对抗原刺激耐受性降低，表明蛋白4.1R与肥大细胞异常活化疾病密切相关；通过比较 BMMC-4.1R+/+和 BMMC-4.1R-/-活化中FcεRI介导的相关信号分子磷酸化水平，发现4.1R抑制FcεRI下游信号分子Lyn，Syk，LAT和 ERK 磷酸化。实验数据表明4.1R通过膜受体FcεRI介导的细胞信号转导负调控肥大细胞活化及脱颗粒。