CD40信号通路：抗CD40单克隆抗体可诱导包括蛋白酪氨酸激酶Lyn、Fyn和Syk在内的酪氨酸磷酸化蛋白快速去磷酸化和磷酸化，并出现一种28-kD的酪氨酸磷酸化蛋白。
CD40 signaling pathway: anti-CD40 monoclonal antibody induces rapid dephosphorylation and phosphorylation of tyrosine-phosphorylated proteins including protein tyrosine kinase Lyn, Fyn, and Syk and the appearance of a 28-kD tyrosine phosphorylated protein.
作者信息
Faris M, Gaskin F, Parsons J T, Fu S M
机构信息
Department of Internal Medicine, University of Virginia Cancer Center, University of Virginia School of Medicine, Charlottesville 22908.
出版信息
J Exp Med. 1994 Jun 1;179(6):1923-31. doi: 10.1084/jem.179.6.1923.
CD40 plays an important role in B cell activation, proliferation, and Ig class switching. The signal transduction pathway mediated by CD40 was studied using monoclonal antibody (mAb) 626.1 to CD40. Burkitt's lymphoma and Epstein-Barr virus-transformed B cell lines and tonsilar B lymphocytes were treated with the anti-CD40 mAb for various lengths of time. The early events triggered by CD40 were examined by monitoring the changes in tyrosine phosphorylation of cellular proteins with anti-phosphotyrosine mAb. Dephosphorylation of specific proteins ranging between 50-110 kD and the appearance of a 28-kD tyrosine phosphorylated protein were seen within 30 s in human B cell lines. The dephosphorylation was reversed and the 28-kD protein was dephosphorylated in cells stimulated for 1 min. In resting B cells, the appearance of the 28-kD phosphoprotein was observed in 30 s after the addition of the anti-CD40 mAb. The tyrosine phosphorylation of this protein persisted. The patterns of protein tyrosine phosphorylation differed from those induced by an anti-immunoglobulin M mAb. The changes in the state of tyrosine phosphorylation induced by the anti-CD40 mAb were obviated by mAb to CD45, a protein tyrosine phosphatase (PTP) or by the addition of sodium orthovanadate, a broad PTP inhibitor. They were also blocked by protein tyrosine kinase (PTK) inhibitors, herbimycin A and genistein, and PKC and protein serine/threonine kinase inhibitors, H7 and HA1004. In addition, the alteration in the tyrosine phosphorylation of PTKs Lyn, Fyn, and Syk was directly demonstrated. Engagement of CD40 for 30 s induced a transient decrease in tyrosine phosphorylation of these PTKs. These results indicate that the early events in CD40 signaling involve the complex interaction between PTP and protein kinases.
CD40在B细胞活化、增殖及免疫球蛋白类别转换中发挥重要作用。利用抗CD40单克隆抗体（mAb）626.1研究了由CD40介导的信号转导途径。用抗CD40 mAb对伯基特淋巴瘤、爱泼斯坦-巴尔病毒转化的B细胞系及扁桃体B淋巴细胞进行不同时长的处理。通过用抗磷酸酪氨酸mAb监测细胞蛋白酪氨酸磷酸化的变化，来检测由CD40触发的早期事件。在人B细胞系中，30秒内可见50 - 110 kD之间特定蛋白的去磷酸化以及一种28 kD酪氨酸磷酸化蛋白的出现。在刺激1分钟的细胞中，去磷酸化被逆转，28 kD蛋白发生去磷酸化。在静息B细胞中，加入抗CD40 mAb后30秒可观察到28 kD磷蛋白的出现。该蛋白的酪氨酸磷酸化持续存在。这种蛋白酪氨酸磷酸化模式不同于由抗免疫球蛋白M mAb诱导的模式。抗CD40 mAb诱导的酪氨酸磷酸化状态变化可被抗CD45 mAb（一种蛋白酪氨酸磷酸酶（PTP））或通过添加偏钒酸钠（一种广谱PTP抑制剂）消除。它们也被蛋白酪氨酸激酶（PTK）抑制剂、除莠霉素A和染料木黄酮以及蛋白激酶C和蛋白丝氨酸/苏氨酸激酶抑制剂H7和HA1004所阻断。此外，直接证明了PTKs Lyn、Fyn和Syk的酪氨酸磷酸化改变。CD40结合30秒会导致这些PTKs的酪氨酸磷酸化短暂降低。这些结果表明，CD40信号传导中的早期事件涉及PTP和蛋白激酶之间的复杂相互作用。
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