Interleukin-13 gene expression is regulated by GATA-3 in T cells - Role of a critical association of a GATA and two GATG motifs
Interleukin-13 gene expression is regulated by GATA-3 in T cells - Role of a critical association of a GATA and two GATG motifs
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DOI：
10.1074/jbc.m110013200
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发表时间：
2002-05-24
影响因子：
4.8
通讯作者：
Max-Audit, I
中科院分区：
文献类型：
--
作者：
Lavenu-Bombled, C;Trainor, CD;Max-Audit, I
使用转基因方法，我们研究了加塔-3在T细胞中的作用。如前所示，转基因小鼠中增强的加塔-3表达抑制了CD 4 T细胞的Th 1分化，但出乎意料的是，1型（干扰素γ）和2型（白细胞介素（IL）-4和IL-13）细胞因子基因在转基因CD 8 T细胞中均被激活。由于IL-13基因表达在体内通过加塔-3表达而高度增强，我们研究了人和小鼠IL-13基因启动子并发现了共有加塔结合位点和两个GATG基序的进化保守关联。我们发现，有效的加塔-3结合到这个调控序列需要这三个基序，并且加塔锌指对这种关联的亲和力是单独的共有加塔结合位点的5倍。在T细胞系中的转染或通过加塔-3的反式激活表明，IL-13基因启动子的完全转录活性需要三个位点的组合。最后，我们表明，这种结合位点的关联导致IL-13基因启动子对加塔-3蛋白水平的微小变化具有非常高的敏感性。总之，这些结果表明加塔-3在CD 8细胞因子基因表达中的重要作用，并证明加塔结合位点的关键网络高度调节加塔-3活性。
Using a transgenic approach, we studied the role of GATA-3 in T cells. As previously shown, enforced GATA-3 expression in transgenic mice inhibits Th1 differentiation of CD4 T cells, but unexpectedly, both type 1 (interferon gamma) and type 2 (interleukin (IL)-4 and IL-13) cytokine genes were activated in the transgenic CD8 T cells. Because IL-13 gene expression was highly enhanced in vivo by GATA-3 expression, we studied the human and the mouse IL-13 gene promoters and found an evolutionary-conserved association of a consensus GATA binding site and two GATG motifs. We showed that efficient GATA-3 binding to this regulatory sequence required these three motifs and that the affinity of the GATA zinc fingers for this association was five times higher than for the consensus GATA binding site alone. Transfections in a T cell line or transactivation by GATA-3 showed that the combination of the three sites was required for full transcriptional activity of the IL-13 gene promoter. Finally we showed that this association of binding sites causes a very high sensitivity of the IL-13 gene promoter to small variations in the level of GATA-3 protein. Altogether, these results indicate an important role of GATA-3 in CD8 cytokine gene expression and demonstrate that a critical network of GATA binding sites highly modulates GATA-3 activity.