Granulocyte-macrophage colony-stimulating factor enhancer activation requires cooperation between NFAT and AP-1 elements and is associated with extensive nucleosome reorganization
Granulocyte-macrophage colony-stimulating factor enhancer activation requires cooperation between NFAT and AP-1 elements and is associated with extensive nucleosome reorganization
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DOI：
10.1128/mcb.24.18.7914-7930.2004
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发表时间：
2004-09-01
影响因子：
5.3
通讯作者：
Cockerill, PN
中科院分区：
文献类型：
--
作者：
Johnson, BV;Bert, AG;Cockerill, PN
人粒细胞-巨噬细胞集落刺激因子(GM-CSF)基因被NFAT依赖的增强子激活，形成可诱导的DNase I超敏(DH)位点。包括DH位点的增强子核心包含协同结合NFAT和AP-1的GM330和GM420元件。在这里，我们证明了这两个元件对于增强子的活性是必不可少的，并且增强子中的Sp1和AML1位点只有在激活后才会在体内占据。染色质结构分析表明，GM-CSF增强子核心元件在两个相邻的核小体之间分配，这两个核小体在激活后变得不稳定和高度可及。可诱导的染色质重组并不局限于增强子核心，而是延伸到动员的核小体的3kb区域，其中核小体重复长度从大约185到150bp被压缩。GM420元件是一个高亲和力位点，它独立于AP-1结合NFAT，但依赖于连接的AP-1位点来发挥增强子功能。然而，仅来自GM420元件的NFAT基序就足以在染色质中形成一个水解酶切位点，即使在没有AP-1的情况下也是如此。因此，NFAT有可能通过促进染色质重塑和增加可诱导调控元件的可及性而与其他转录因子合作。
The human granulocyte-macrophage colony-stimulating factor (GM-CSF) gene is activated by an NFAT-dependent enhancer forming an inducible DNase I hypersensitive (DH) site. The enhancer core comprising the DH site contains the GM330 and GM420 elements that bind NFAT and AP-1 cooperatively. Here we demonstrate that both elements are essential for enhancer activity and that Sp1 and AML1 sites in the enhancer become occupied in vivo only after activation. Chromatin structure analysis revealed that the GM-CSF enhancer core elements are divided between two adjacent nucleosomes that become destabilized and highly accessible after activation. Inducible chromatin reorganization was not restricted to the enhancer core but extended across a 3-kb domain of mobilized nucleosomes, within which the nucleosome repeat length was compressed from approximately 185 to 150 bp. The GM420 element is a high-affinity site that binds NFAT independently of AP-1 but depends on the linked AP-1 site for enhancer function. Nevertheless, just the NFAT motif from the GM420 element was sufficient to form a DH site within chromatin even in the absence of the AP-1 site. Hence, NFAT has the potential to cooperate with other transcription factors by promoting chromatin remodelling and increasing accessibility at inducible regulatory elements.