Differential regulation of CXCR4-mediated T-cell chemotaxis and mitogen-activated protein kinase activation by the membrane tyrosine phosphatase, CD45
Differential regulation of CXCR4-mediated T-cell chemotaxis and mitogen-activated protein kinase activation by the membrane tyrosine phosphatase, CD45
复制标题
DOI：
10.1074/jbc.m211803200
复制
发表时间：
2003-03-14
影响因子：
4.8
通讯作者：
Ganju, RK
中科院分区：
文献类型：
--
作者：
Fernandis, AZ;Cherla, RP;Ganju, RK
趋化因子受体CXCR 4及其同源配体基质细胞衍生因子-l α（CXCL 12）调节淋巴细胞运输并在宿主免疫监视中起重要作用。然而，涉及CXCL12诱导和CXCR4介导的T淋巴细胞趋化性的分子机制尚未完全阐明。在本研究中，我们研究了膜酪氨酸磷酸酶CD45的作用，它调节抗原受体信号在CXCR4介导的趋化性和丝裂原活化蛋白激酶（MAPK）激活的T细胞。我们观察到与CD45阳性对照（JE6.1）细胞相比，CD45阴性Jurkat细胞系（J45.01）中CXCL 12诱导的趋化性显著降低。表达含有CD45胞内磷酸酶结构域的嵌合蛋白能够部分恢复J45.01细胞中CXCL12诱导的趋化性。然而，将CD45重建到J45.01细胞中使CXCL 12诱导的趋化性恢复至约90%。CD45对CXCL12或人类免疫缺陷病毒gp120诱导的CXCR4受体内化没有显著影响。此外，与JE6.1细胞相比，J45.01细胞显示CXCL 12诱导的MAP激酶活性轻微增强。我们还观察到CXCL12处理增强了CD45的酪氨酸磷酸化，并诱导其与CXCR4受体的结合。用脂筏抑制剂甲基-β-环糊精预处理T细胞，阻断了CXCR4和CD45之间的结合，并显著消除了CXCL12诱导的趋化性。比较CXCL12在JE6.1和J45.01细胞中诱导的信号通路发现，CD45可能适度调节粘着斑组分的酪氨酸磷酸化，相关的粘着斑酪氨酸激酶/Pyk2、粘着斑激酶、p130Cas和桩蛋白。CD45还显示调节CXCR4介导的T细胞受体下游效应物Lck、ZAP-70和SLP-76的活化和磷酸化。我们的研究结果表明，CD45差异调节CXCR4介导的趋化活性和MAPK激活通过调节粘着斑成分和下游效应的T细胞受体的活动。
The chemokine receptor CXCR4 and its cognate ligand, stromal cell-derived factor-lalpha (CXCL12), regulate lymphocyte trafficking and play an important role in host immune surveillance. However, the molecular mechanisms involved in CXCL12-induced and CXCR4-mediated chemotaxis of T-lymphocytes are not completely elucidated. In the present study, we examined the role of the membrane tyrosine phosphatase CD45, which regulates antigen receptor signaling in CXCR4-mediated chemotaxis and mitogen-activated protein kinase (MAPK) activation in T-cells. We observed a significant reduction in CXCL12-induced chemotaxis in the CD45-negative Jurkat cell line (J45.01) as compared with the CD45-positive control (JE6.1) cells. Expression of a chimeric protein containing the intracellular phosphatase domain of CD45 was able to partially restore CXCL12-induced chemotaxis in the J45.01 cells. However, reconstitution of CD45 into the J45.01 cells restored the CXCL12-induced chemotaxis to about 90%. CD45 had no significant effect on CXCL12 or human immunodeficiency virus gp120-induced internalization of the CXCR4 receptor. Furthermore, J45.01 cells showed a slight enhancement in CXCL12-induced MAP kinase activity as compared with the JE6.1 cells. We also observed that CXCL12 treatment enhanced the tyrosine phosphorylation of CD45 and induced its association with the CXCR4 receptor. Pretreatment of T-cells with the lipid raft inhibitor, methyl-beta-cyclodextrin, blocked the association between CXCR4 and CD45 and markedly abolished CXCL12-induced chemotaxis. Comparisons of signaling pathways induced by CXCL12 in JE6.1 and J45.01 cells revealed that CD45 might moderately regulate the tyrosine phosphorylation of the focal adhesion components the related adhesion focal tyrosine kinase/Pyk2, focal adhesion kinase, p130Cas, and paxillin. CD45 has also been shown to regulate CXCR4-mediated activation and phosphorylation of T-cell receptor downstream effectors Lck, ZAP-70, and SLP-76. Our results show that CD45 differentially regulates CXCR4-mediated chemotactic activity and MAPK activation by modulating the activities of focal adhesion components and the downstream effectors of the T-cell receptor.