Altered lipid raft-associated proximal signaling and translocation of CD45 tyrosine phosphatase in B lymphocytes from patients with systemic lupus erythematosus
Altered lipid raft-associated proximal signaling and translocation of CD45 tyrosine phosphatase in B lymphocytes from patients with systemic lupus erythematosus
复制标题
DOI：
10.1002/art.22309
复制
发表时间：
2007-01-01
影响因子：
--
通讯作者：
Mageed, Rizgar A.
中科院分区：
文献类型：
--
作者：
Flores-Borja, Fabian;Kabouridis, Panagiotis S.;Mageed, Rizgar A.
Objective.系统性红斑狼疮（SLE）患者的B淋巴细胞表现出细胞内信号传导缺陷、活性亢进和自身抗体产生。最近的证据表明，在SLE中，林恩激酶（B细胞信号传导的负调节剂）的表达减少，并且林恩易位到膜信号传导结构域减少。本研究通过评估调节分子的表达水平及其易位到SLE B淋巴细胞的信号传导结构域来调查这种改变林恩调节的原因。从48例SLE患者和28例健康对照者中采集血液用于B淋巴细胞的评估。通过Western印迹、共聚焦显微镜和流式细胞术研究了林恩、CD 45、COOH末端Src激酶（Csk）和c-Cbl的水平和细胞内分布。用共聚焦显微镜观察信号分子向B细胞受体（BCR）-抗原突触转运的动力学。观察到SLE患者B细胞膜结构域中调节信号分子的表达和易位发生了深刻的变化。SLE患者的B淋巴细胞在脂筏信号微结构域中表达低分子量的CD 45亚型，而健康对照者的B淋巴细胞则不表达。动力学研究显示，林恩、CD 45、Csk和c-Cbl的易位导致林恩和CD 45在SLE B细胞BCR-抗原突触中的募集和滞留增加。这些结果提供了SLE患者B细胞膜信号微区中激酶和磷酸酶表达改变和易位/相互作用的证据。CD 45易位改变与林恩表达减少相关，表明林恩是BCR介导信号调节的关键分子。
Objective. B lymphocytes from patients with systemic lupus erythematosus (SLE) exhibit defective intracellular signaling, hyperactivity, and autoantibody production. Recent evidence indicates a reduced expression of Lyn kinase, a negative regulator of B cell signaling, and reduced translocation of Lyn into membrane signaling domains in SLE. The present study was undertaken to investigate the causes of this altered regulation of Lyn by assessing the expression levels of regulatory molecules and their translocation into the signaling domains of SLE B lymphocytes.Methods. Blood was obtained from 48 patients with SLE and 28 healthy controls for the assessment of B lymphocytes. Levels and intracellular distribution of Lyn, CD45, COOH-terminal Src kinase (Csk), and c-Cbl were studied by Western blotting, confocal microscopy, and flow cytometry. The kinetics of signaling molecule translocation to the B cell receptor (BCR)-antigen synapse were investigated by confocal microscopy.Results. A profound alteration in the expression and translocation of regulatory signaling molecules in membrane domains of B cells from patients with SLE was observed. B lymphocytes from SLE patients, but not those from healthy controls, expressed a low molecular weight isoform of CD45 in lipid raft signaling microdomains. Kinetic studies revealed that translocation of Lyn, CD45, Csk, and c-Cbl led to increased recruitment and retention of Lyn and CD45 in the BCR-antigen synapse in SLE B cells.Conclusion. The results provide evidence of altered expression and translocation/interaction of kinases and phosphatases in membrane signaling microdomains of B cells from patients with SLE. Altered translocation of CD45 correlated with reduced expression of Lyn, indicating that Lyn is a key molecule in the regulation of BCR-mediated signaling.