Genomic targets of the human c-Myc protein
Genomic targets of the human c-Myc protein
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DOI：
10.1101/gad.1067003
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发表时间：
2003-05-01
影响因子：
10.5
通讯作者：
Amati, B
中科院分区：
文献类型：
--
作者：
Fernandez, PC;Frank, SR;Amati, B
转录因子Myc由促有丝分裂信号诱导并调节下游细胞反应。如果过表达，Myc促进恶性转化。Myc在实验系统中调节不同基因的表达，但很少被证明是直接靶点。在这里，我们提出了一个大规模的屏幕基因组Myc结合位点在活的人类细胞。我们使用生物信息学来选择位于基因5'调控区的共有DNA元件（CACGTG或E盒），并通过定量染色质免疫沉淀来测量Myc与这些序列的体内结合。引人注目的是，大多数启动子相关的E盒显示出与Myc的选择性恢复，不像非E盒启动子或大量基因组DNA中的E盒。启动子E盒以不同的频率分布在与Myc结合的两组中。高亲和力组包括所有细胞位点的估计11%，在不同细胞中高度保守，并且独立于Myc表达水平结合。过表达的Myc与低亲和力靶点的频率增加相关，并且在极端水平下，也与其他序列相关，这表明某些结合不是序列特异性的。定义高亲和力靶点的最强DNA序列参数是CpG岛内E盒的位置，与染色质的开放、预乙酰化状态相关。Myc进一步增强组蛋白乙酰化，伴随或不伴随mRNA表达的诱导。我们的研究结果表明，Myc靶基因之间具有高度的调控和生物多样性。
The transcription factor Myc is induced by mitogenic signals and regulates downstream cellular responses. If overexpressed, Myc promotes malignant transformation. Myc modulates expression of diverse genes in experimental systems, but few are proven direct targets. Here, we present a large-scale screen for genomic Myc-binding sites in live human cells. We used bioinformatics to select consensus DNA elements (CACGTG or E-boxes) situated in the 5' regulatory region of genes and measured Myc binding to those sequences in vivo by quantitative chromatin immunoprecipitation. Strikingly, most promoter-associated E-boxes showed selective recovery with Myc, unlike non-E-box promoters or E-boxes in bulk genomic DNA. Promoter E-boxes were distributed in two groups bound by Myc at distinct frequencies. The high-affinity group included an estimated 11% of all cellular loci, was highly conserved among different cells, and was bound independently of Myc expression levels. Overexpressed Myc associated at increased frequency with low-affinity targets and, at extreme levels, also with other sequences, suggesting that some binding was not sequence-specific. The strongest DNA-sequence parameter defining high-affinity targets was the location of E-boxes within CpG islands, correlating with an open, preacetylated state of chromatin. Myc further enhanced histone acetylation, with or without accompanying induction of mRNA expression. Our findings point to a high regulatory and biological diversity among Myc-target genes.