Chemokines Induce Wnt-Frizzled Gene Expression in Human T Cells

趋化因子在体外和体内均可诱导和指导人类和啮齿动物白细胞的粘附、趋化、激活和脱颗粒。CXCL12和CCL19是两个重要的趋化因子，在正常和炎症条件下调节T细胞的运动和激活。尽管有许多研究趋化因子功能的报告，但对其中涉及的转录事件知之甚少。在这里，我们对CXCL12处理的t细胞进行了微阵列分析，发现Wnt家族蛋白在CXCL12处理期间显著上调。real-time PCR和Western分析证实了这些结果，发现在CXCL12刺激时，Wnt5A和其他非典型Wnt通路成员的表达被特异性上调，而-catenin和典型Wnt家族成员的表达被选择性下调。发现Wnt5A通过激活蛋白激酶C （PKC）增强CXCL12-CXCR4轴的信号传导。此外，我们的数据显示，Wnt5A表达是介导t细胞定向迁移以响应CXCL12的必要条件，并且重组Wnt5A处理人t细胞使t细胞对CXCL12诱导的迁移敏感。此外，Wnt5A的表达也是CXCR4在转录和翻译上持续表达所必需的。这些结果在体内得到进一步的支持，使用EL4胸腺瘤转移作为t细胞迁移模型。综上所述，这些数据首次证明Wnt5A是人类和小鼠T细胞中CXCL12-CXCR4信号传导和迁移的关键介质。有趣的是，我们还发现Wnt10A在CCL19趋化和维持CCR7在T细胞上的表达中发挥作用。这些发现可能揭示了多种趋化因子和Wnt受体及配体之间的新型合作信号网络，可能控制细胞极化和定向迁移。

Chemokines have been shown to induce and direct adhesion, chemotaxis, activation, and degranulation of human and rodent leukocytes both in vitro and in vivo. CXCL12 and CCL19 are two important chemokines that regulate T cell motility and activation under normal and inflammatory conditions. Despite numerous reports examining the function of chemokines, little is known about the transcriptional events involved therein. Here, we performed microarray analysis on CXCL12- treated T-cells, and found that the Wnt family of proteins was significantly upregulated during CXCL12 treatment. Confirmation of these results by real-time PCR and Western analysis revealed that the expression of Wnt5A and other members of the non-canonical Wnt pathway were specifically upregulated during CXCL12 stimulation, while -catenin and canonical Wnt family members were selectively downregulated. Wnt5A was found to augment signaling through the CXCL12-CXCR4 axis via the activation of protein kinase C (PKC). Moreover, our data has revealed that Wnt5A expression is required to mediate directional T-cell migration in response to CXCL12, and that the treatment of human T-cells with recombinant Wnt5A sensitized T-cells to CXCL12-induced migration. Furthermore,Wnt5A expression was also required for the sustained expression of CXCR4, both transcriptionally and translationally. These results were further supported in vivo using EL4 thymoma metastasis as a model of T-cell migration. Together, these data demonstrate, for the first time, that Wnt5A is a critical mediator in CXCL12-CXCR4 signaling and migration in human and murine T cells. Interestingly, we also found that Wnt10A plays a role in CCL19 chemotaxis and in the maintenance of CCR7 expression on T cells. These findings may reveal a novel cooperative signaling network between various chemokine and Wnt receptors and ligands that may control cell polarization and directional migration. Moreover, we are also currently verifying and characterizing several additional gene families that are highly expressed in T cells after migration in response to or simply stimulation with CXCL12, CCL19, gp120 and HIV-1 virus. Moreover, the role of lipid rafts in chemokine biology and HIV infectivity are also under examination using microarray analysis. A greater understanding of the transcriptional signals differentially induced by the ligation of various chemokine receptors may provide a means to dissect the pathways by which these chemoattractants induce cell migration and activation as well as any host transcriptional signals important in HIV entry and replication.