Deficiency of BLNK hampers PLC-γ2 phosphorylation and Ca2+ influx induced by the pre-B-cell receptor in human pre-B cells
Deficiency of BLNK hampers PLC-γ2 phosphorylation and Ca2+ influx induced by the pre-B-cell receptor in human pre-B cells
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DOI：
10.1111/j.1365-2567.2004.01918.x
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发表时间：
2004-08-01
期刊：
影响因子：
6.4
通讯作者：
Fujimoto, J
中科院分区：
文献类型：
--
作者：
Taguchi, T;Kiyokawa, N;Fujimoto, J
B 细胞连接蛋白 (BLNK) 是 B 细胞受体 (BCR) 以及前 BCR 信号通路的组成部分，BLNK-/- 小鼠在前 B/前 B 细胞阶段 B 淋巴细胞生成受阻。最近的一份报告描述了大约 50% 的人类儿童 pre-B 急性淋巴细胞白血病 (ALL) 中 BLNK 表达完全丧失或急剧减少，因此我们研究了人类 pre-B ALL 细胞系中的 BLNK 表达。测试的四种细胞系之一 HPB-NULL 细胞被发现缺乏 BLNK 表达，我们使用这些表达和不表达 BLNK 的人类前 B ALL 细胞系来研究前 BCR 交联后的细胞内信号传导事件。当前 BCR 与抗 mu 重链抗体交联时，观察到细胞内分子（包括 Syk、Shc、ERK MAP 激酶和 AKT）显着磷酸化，并且在不考虑 BLNK 表达缺陷的情况下观察到 Ras 的激活，这表明 BLNK 不是前 BCR 介导的 MAP 激酶和磷脂酰肌醇 3 (PI3) 激酶信号传导激活所必需的。相比之下，仅在表达 BLNK 的细胞中观察到磷脂酶 C-gamma2 (PLC-gamma2) 磷酸化和由前 BCR 交联介导的细胞内 Ca2+ 水平增加，表明 BLNK 对于 PLC-gamma2 诱导的 Ca2+ 流入至关重要。表达和不表达 BLNK 的人类前 B 细胞系应该为研究 BLNK 在前 BCR 介导的信号传导机制中的作用提供体外模型。
B-cell linker protein (BLNK) is a component of the B-cell receptor (BCR) as well as of the pre-BCR signalling pathway, and BLNK-/- mice have a block in B lymphopoiesis at the pro-B/pre-B cell stage. A recent report described the complete loss or drastic reduction of BLNK expression in approximately 50% of human childhood pre-B acute lymphoblastic leukaemias (ALL), therefore we investigated BLNK expression in human pre-B ALL cell lines. One of the four cell lines tested, HPB-NULL cells, was found to lack BLNK expression, and we used these human pre-B ALL cell lines that express and do not express BLNK to investigate the intracellular signalling events following pre-BCR cross-linking. When pre-BCR was cross-linked with anti-mu heavy-chain antibodies, significant phosphorylation of intracellular molecules, including Syk, Shc, ERK MAP kinase, and AKT, and an activation of Ras were observed without regard to deficiency of BLNK expression, suggesting that BLNK is not required for pre-BCR-mediated activation of MAP kinase and phosphatidyl-inositol 3 (PI3) kinase signalling. By contrast, phospholipase C-gamma2 (PLC-gamma2) phosphorylation and an increase in intracellular Ca2+ level mediated by pre-BCR cross-linking were observed only in the BLNK-expressing cells, indicating that BLNK is essential for PLC-gamma2-induced Ca2+ influx. Human pre-B cell lines expressing and not expressing BLNK should provide an in vitro model for investigation of the role of BLNK in the pre-BCR-mediated signalling mechanism.