NOTCH1-RBPJ complexes drive target gene expression through dynamic interactions with superenhancers
NOTCH1-RBPJ complexes drive target gene expression through dynamic interactions with superenhancers
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DOI：
10.1073/pnas.1315023111
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发表时间：
2014-01-14
影响因子：
11.1
通讯作者：
Aster, Jon C.
中科院分区：
文献类型：
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作者：
Wang, Hongfang;Zang, Chongzhi;Aster, Jon C.
T淋巴细胞白血病中的主要致癌驱动因子是NOTCH 1，其通过形成染色质相关的Notch转录复合物来激活基因。γ-分泌酶抑制剂治疗阻止NOTCH 1核定位，但大多数具有NOTCH 1结合位点的基因对γ-分泌酶抑制剂不敏感。在这里，我们表明，不到10%的NOTCH 1结合位点显示动态变化的NOTCH 1占用T淋巴细胞白血病细胞之间的Notch-on和-off状态与γ-分泌酶抑制剂切换。动态NOTCH 1位点是功能性的，与Notch靶基因高度相关，主要位于远端增强子中，并且经常与RUNX 1结合重叠。与后一种关联一致，我们发现IL 7 R（一种在正常T细胞发育和T淋巴细胞白血病中具有关键作用的基因）的表达受Runx因子和与远端增强子结合的动态NOTCH 1的协调调节。与IL 7 R一样，大多数Notch靶基因和相关的动态NOTCH 1结合位点共同占据由CCCTC结合因子的组成性结合所定义的染色质结构域，这似乎限制了动态NOTCH 1位点的调控潜力。更值得注意的是，大多数动态NOTCH 1位点位于超增强子中，即具有异常广泛和高水平H3 K27 ac的远端元件。Notch占据率的变化在整个超增强子宽度和Notch靶基因的启动子中产生H3 K27 ac水平的动态改变。这些发现将超增强子功能的调节与NOTCH 1（未成熟T细胞背景下的主要调节因子和强效癌蛋白）联系起来，并描绘了用于识别细胞基因组中功能性Notch位点的普遍适用的路线图。
The main oncogenic driver in T-lymphoblastic leukemia is NOTCH1, which activates genes by forming chromatin-associated Notch transcription complexes. Gamma-secretase-inhibitor treatment prevents NOTCH1 nuclear localization, but most genes with NOTCH1-binding sites are insensitive to gamma-secretase inhibitors. Here, we demonstrate that fewer than 10% of NOTCH1-binding sites show dynamic changes in NOTCH1 occupancy when T-lymphoblastic leukemia cells are toggled between the Notch-on and -off states with gamma-secretase inhibiters. Dynamic NOTCH1 sites are functional, being highly associated with Notch target genes, are located mainly in distal enhancers, and frequently overlap with RUNX1 binding. In line with the latter association, we show that expression of IL7R, a gene with key roles in normal T-cell development and in T-lymphoblastic leukemia, is coordinately regulated by Runx factors and dynamic NOTCH1 binding to distal enhancers. Like IL7R, most Notch target genes and associated dynamic NOTCH1-binding sites cooccupy chromatin domains defined by constitutive binding of CCCTC binding factor, which appears to restrict the regulatory potential of dynamic NOTCH1 sites. More remarkably, the majority of dynamic NOTCH1 sites lie in superenhancers, distal elements with exceptionally broad and high levels of H3K27ac. Changes in Notch occupancy produces dynamic alterations in H3K27ac levels across the entire breadth of superenhancers and in the promoters of Notch target genes. These findings link regulation of superenhancer function to NOTCH1, a master regulatory factor and potent oncoprotein in the context of immature T cells, and delineate a generally applicable roadmap for identifying functional Notch sites in cellular genomes.