AKT2通过正反馈调控CD19磷酸化促进B细胞激活和功能的机制研究

AKT2 is one of the subtypes of AKT associated with type II diabetes and malignant tumors, and mainly expressed in the organs involved in metabolism. It has been reported that AKT2 is highly expressed in B cells compared with other AKT subtypes, but the function of AKT2 in B cells and in the humoral immunity is not known yet. In the previous study, we found that the early activation of B cells from AKT2 deficient mice was impaired. In the AKT2 deficient B cells, the expansion ability, BCR signaling and the actin remodeling after activation in vitro were influenced, however, the molecular mechanism is not clear yet. In this project, with the usage of AKT2-/- mice, we will further study (1) the effect of AKT2 in BCR signaling by TIRFM and CFm; (2) the specific changes of actin remodeling through G-actin polymerization and lifeAct AKT2-/- mice model. Meanwhile, by detecting the early activation of B cells in the over expressed CD19 B cells in vitro, and the expression and ubiquitination of Lyn, the up regulator of CD19, in AKT2 deficient mice, as well as the specific immune globulin in the AKT2 deficient mice after immunization, we aim to provide the new mechanism that the AKT2 modulates the humoral immune through regulating the early activation of B cells via the activation of CD19.The study is aim to provide the theory basis for the production of vaccines.

AKT2是与II型糖尿病和恶性肿瘤相关的AKT亚型，主要表达在与代谢相关的器官中。有研究发现AKT2在B细胞中具有较高水平的表达，但在B细胞及体液免疫中的作用尚不明确。我们前期研究发现缺失AKT2的小鼠B细胞早期激活能力受损，AKT2缺失的小鼠B细胞在激活后扩张能力和BCR信号均减弱，肌动蛋白的重构亦受到影响，但其分子机制尚不清楚。本课题拟以AKT2-/-小鼠为研究对象，运用激光共聚焦和全内反射荧光显微镜等技术明确AKT2对BCR信号的影响，同时分别采用G-肌动蛋白和lifeAct小鼠模型深入探究AKT2对B细胞肌动蛋白重构的作用，并通过过表达CD19以及对CD19上游分子Lyn的基因、蛋白表达水平及泛素化水平的检测，结合分析免疫后小鼠的生发中心细胞及血清中特异性免疫球蛋白的含量，最终揭示AKT2通过CD19调控B细胞早期激活进而影响体液免疫的全新分子机制，该研究将为疫苗设计提供理论基础。

AKT2是与II型糖尿病和恶性肿瘤相关的AKT亚型，主要表达在与代谢相关的器官中。有研究发现AKT2在B细胞中具有较高水平的表达，但在B细胞及体液免疫中的作用尚不明确。我们研究发现AKT2通过增强BCR信号通路和肌动蛋白重塑促进B细胞早期活化。体外刺激AKT2 KO小鼠的B细胞出现扩散缺陷和BCR聚类。btk介导的信号中断导致生发中心B细胞分化受损，免疫AKT2 KO小鼠血清特异性IgM和IgG水平下降。此外，在AKT2 KO小鼠中，由于肌动蛋白聚合调节剂WASP的激活水平降低，肌动蛋白重构也受到影响。CD19作为B细胞活化早期BCR信号通路和肌动蛋白重塑的关键调节因子，在AKT2缺失的B细胞中，CD19的磷酸化水平下降，而转录水平正常。我们揭示了AKT2通过CD19调控B细胞早期激活进而影响体液免疫的全新分子机制，该研究将为疫苗设计提供理论基础。