C/EBPalpha binds and activates the PU.1 distal enhancer to induce monocyte lineage commitment.
C/EBPalpha binds and activates the PU.1 distal enhancer to induce monocyte lineage commitment.
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DOI：
10.1182/blood-2007-03-080291
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发表时间：
2007-11
期刊：
影响因子：
20.3
通讯作者：
C. Yeamans;Dehua Wang;I. Paz‐Priel;B. Torbett;D. Tenen;A. Friedman
中科院分区：
文献类型：
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作者：
C. Yeamans;Dehua Wang;I. Paz‐Priel;B. Torbett;D. Tenen;A. Friedman
PU.1基因含有一个237个碱基对的远端增强子，位于其启动子上游14个碱基处。我们已经确定了PU.1增强子中的2个位点，其在凝胶迁移试验中强烈结合C/EBPalpha，并且通过染色质免疫沉淀证实了与内源性C/EBPalpha的相互作用。这些DNA元件的突变降低了远端增强子-启动子构建体在髓样细胞系中的活性2或5倍，而位于启动子中的较弱C/EBPa结合位点的突变最低限度地降低了这种情况下的活性。这些发现加强了C/EBPalpha和PU.1表达之间的联系。因此，在急性髓性白血病的情况下，C/EBPalpha活性的降低可能通过降低PU.1水平而有助于转化。此外，在正常造血过程中，C/EBPalpha对PU.1的诱导可能有助于干细胞向骨髓谱系的定型和进一步向单细胞生成的定型。与髓系发育过程中对PU.1的C/EBPalpha诱导的要求一致，我们证明C/EBPalpha在PU.1（+/+）、PU.1（+/-）或PU.1（+/kd）骨髓髓系祖细胞中表达时诱导单核细胞发育，但在缺乏PU.1远端增强子的PU.1（kd/kd）细胞中诱导粒细胞谱系定型，并且在PU.1（-/-）细胞中不诱导任一谱系。
The PU.1 gene contains a 237-base pair distal enhancer located 14 kilobases upstream of its promoter. We have identified 2 sites within the PU.1 enhancer that strongly bind C/EBPalpha in a gel shift assay, and interaction with endogenous C/EBPalpha was confirmed by chromatin immunoprecipitation. Mutation of these DNA elements reduced activity of a distal enhancer-promoter construct 2- or 5-fold in a myeloid cell line, while mutation of a weaker C/EBPalpha-binding site located in the promoter minimally reduced activity in this context. These findings strengthen the link between C/EBPalpha and PU.1 expression. Reduction of C/EBPalpha activity in cases of acute myeloid leukemia may therefore contribute to transformation by reducing PU.1 levels. In addition, induction of PU.1 by C/EBPalpha during normal hematopoiesis may contribute to stem cell commitment to the myeloid lineages and further commitment to monopoiesis. Consistent with a requirement for C/EBPalpha induction of PU.1 during myeloid development, we demonstrate that C/EBPalpha induces monocytic development when expressed in PU.1(+/+), PU.1(+/-), or PU.1(+/kd) marrow myeloid progenitors but induces granulocyte lineage commitment in PU.1(kd/kd) cells lacking the PU.1 distal enhancer and does not induce either lineage in PU.1(-/-) cells.