CCR3 is a chemokine receptor that mediates the accumulation of allergic inflammatory cells, including eosinophils and Th2 cells, at inflamed sites. The regulatory sequence of the CCR3 gene, contains two Runt-related transcription factor (RUNX) 1 sites and two PU.1 sites, in addition to a functional GATA site for transactivation of the CCR3 gene. In the present study, we examined the effects of the cis-acting elements of RUNX1 and PU.1 on transcription of the gene in EoL-1 eosinophilic cells and Jurkat T cells, both of which expressed functional surface CCR3 and these two transcription factors. Introduction of RUNX1 siRNA or PU.1 siRNA resulted in a modest decrease in CCR3 reporter activity in both cell types, compared with transfection of GATA-1 siRNA. Cotransfection of the two siRNAs led to inhibition in an additive manner. EMSA analysis showed that RUNX1, in particular, bound to its binding motifs. Mutagenesis analysis revealed that all point mutants lacking RUNX1- and PU.1-binding sites exhibited reduced reporter activities. These results suggest that RUNX1 and PU.1 participate in transcriptional regulation of the CCR3 gene.

中文翻译：

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RUNX1 和 PU.1 在 CCR3 转录中的作用

CCR3 是一种趋化因子受体，可介导过敏性炎症细胞（包括嗜酸性粒细胞和 Th2 细胞）在发炎部位的积聚。CCR3 基因的调控序列包含两个 Runt 相关转录因子 (RUNX) 1 位点和两个 PU.1 位点，此外还有一个用于 CCR3 基因反式激活的功能性 GATA 位点。在本研究中，我们检测了 RUNX1 和 PU.1 的顺式作用元件对 EoL-1 嗜酸性细胞和 Jurkat T 细胞中基因转录的影响，这两种细胞均表达功能性表面 CCR3 和这两种转录因子。与转染 GATA-1 siRNA 相比，引入 RUNX1 siRNA 或 PU.1 siRNA 导致两种细胞类型中 CCR3 报告基因活性的适度降低。两种 siRNA 的共转染导致以加性方式抑制。EMSA 分析显示 RUNX1 特别是与其结合基序结合。诱变分析表明，所有缺乏 RUNX1 和 PU.1 结合位点的点突变体都表现出降低的记者活动。这些结果表明 RUNX1 和 PU.1 参与 CCR3 基因的转录调控。