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。我们最近对CXCL12-和ccl19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。在CXCL12研究中，我们发现在配体刺激T细胞时，Wnt5A和其他非典型Wnt通路成员的表达被特异性上调，而β -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。有趣的是，在ccl19处理的T细胞中，我们发现Wnt10A而不是Wnt5A在ccl19介导的趋化和维持CCR7在T细胞上的表达中起作用。我们最近发现T细胞表达Klotho蛋白，免疫细胞中Klotho蛋白的表达随着年龄的增长而下降。我们发现T细胞Klotho水平的过表达会降低T细胞Wnt的表达，也会降低趋化因子受体的表达。相反，在T细胞中敲低Klotho表达导致Wnt5a和Wnt10A水平和趋化因子受体表达增加。这项工作最近已经完成，关于这些数据的几份手稿正在编写中，以便可能出版。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。此外，在这些研究中，我们还验证和表征了几个额外的基因家族，这些基因家族在响应CXCL12、CCL19、gp120和HIV-1病毒的刺激或迁移后在T细胞中高度表达。此外，脂筏在趋化因子生物学和HIV感染中的作用也正在使用微阵列分析进行研究。对各种趋化因子受体连接诱导的转录信号的进一步了解，可能为剖析这些趋化因子诱导细胞迁移和激活的途径以及在HIV进入和复制中重要的宿主转录信号提供了一种手段。这是相关的，因为T细胞中Wnt表达的调节通过调节相关趋化因子共受体的表达来调节细胞的HIV-1感染性。

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. We have recently performed microarray analysis on CXCL12- and CCL19-treated T-cells, and found that the Wnt family of proteins was significantly upregulated during CXCL12 treatment. In the CXCL12 studies, we found that the expression of Wnt5A and other members of the non-canonical Wnt pathway were specifically upregulated during ligand stimulation of T cells, while beta-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. Interestingly, in CCL19-treated T cells, we found that Wnt10A, not Wnt5A plays a role in CCL19-mediated chemotaxis and in the maintenance of CCR7 expression on T cells. We have recently found that T cells express the Klotho protein and the expression of Klotho in immune cells declines with age. We have found that over-expression of T cell Klotho levels diminishes T-cell Wnt expression and also diminishes chemokine receptor expression. In contrast, knockdown of T cell Klotho expression in T cells resulted in increases in Wnt5a and Wnt10A levels and chemokine receptor expression. This work has recently been completed and several manuscripts on these data are being written up for possible publication. 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, under these studies, we have also been 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. This is relevant as modulation of Wnt expression in T cells modulates the HIV-1 infectivity of a cell through the regulation of relevant chemokine co-receptor expression. Klotho gene expression was examined in murine and human CD4+T cells as a function of age. In both systems basal expression of Klotho gene decreased with age.