Thomas R S, Tymms M J, McKinlay L H, Shannon M F, Seth A, Kola I
Molecular Genetics and Development Group, Institute of Reproduction and Development, Monash University, Melbourne, Australia.
Oncogene. 1997 Jun 12;14(23):2845-55. doi: 10.1038/sj.onc.1201125.
Activation of helper T cells results in coordinate expression of a number of cytokines involved in differentiation, proliferation and activation of the haematopoietic system. Granulocyte-macrophage colony stimulating factor (GM-CSF) is one such cytokine, whose increased expression results mostly from increases in transcription. Cis-acting elements with NFkappaB, AP1 and ETS-like binding motifs have been identified in the promoter region of the GM-CSF gene, and are important or essential for transcriptional activity following T cell activation. ETS1 is a transcription factor of the ETS family that is expressed in T cells. We have previously shown that ETS1 can transactivate GM-CSF in Jurkat T cells, but only after the cells have been stimulated by treatment with PMA and ionomycin, agents that mimic T cell activation. Thus we proposed that ETS1, which is expressed constitutively in Jurkat cells, may act in concert with PMA/ionomycin inducible factors. Here we show that ETS1 can transactivate a GM-CSF reporter construct in unstimulated Jurkat cells, providing that either NFkappaB or AP1 transcription factors are supplied by co-transfection. We confirm that binding of endogenous NFkappaB and AP1 is induced following PMA/ionomycin treatment of T cells. Transactivation by ETS1, NFkappaB and AP1 is synergistic, and mutation of the individual binding sites reveals that the transcriptional activities of these factors are interdependent. Our results suggest that constitutive ETS1, and inducible NFkappaB and AP1, cooperate as part of a higher order transcriptional complex in activated T cells.
辅助性T细胞的激活会导致多种参与造血系统分化、增殖和激活的细胞因子协同表达。粒细胞-巨噬细胞集落刺激因子（GM-CSF）就是这样一种细胞因子，其表达增加主要源于转录水平的提高。在GM-CSF基因的启动子区域已鉴定出具有NFκB、AP1和ETS样结合基序的顺式作用元件，它们对于T细胞激活后的转录活性很重要或必不可少。ETS1是ETS家族的一种转录因子，在T细胞中表达。我们之前已经表明，ETS1可以在Jurkat T细胞中转录激活GM-CSF，但只有在用佛波酯（PMA）和离子霉素处理模拟T细胞激活的细胞后才会发生。因此我们提出，在Jurkat细胞中组成性表达的ETS1可能与PMA/离子霉素诱导因子协同作用。在此我们表明，只要通过共转染提供NFκB或AP1转录因子，ETS1就可以在未刺激的Jurkat细胞中转录激活GM-CSF报告基因构建体。我们证实，T细胞经PMA/离子霉素处理后会诱导内源性NFκB和AP1的结合。ETS1、NFκB和AP1的转录激活是协同的，单个结合位点的突变表明这些因子的转录活性是相互依赖的。我们的结果表明，组成性的ETS1以及诱导性的NFκB和AP1作为活化T细胞中更高阶转录复合物的一部分协同作用。
