Thrombopoietin regulates IEX-1 gene expression through ERK-induced AML1 phosphorylation
Thrombopoietin regulates IEX-1 gene expression through ERK-induced AML1 phosphorylation
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DOI：
10.1182/blood-2005-07-2953
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发表时间：
2006-04-15
期刊：
影响因子：
20.3
通讯作者：
Gaudry, M
中科院分区：
文献类型：
--
作者：
Hamelin, V;Letourneux, C;Gaudry, M
细胞外信号调节激酶（ERK）是造血细胞血小板生成素（TPO）功能所必需的，但涉及的ERKS靶点仍不清楚。在这里，我们表明，立即早期基因X-1（IEX-1），确定为响应TPO的ERK底物的调节，介导的AML 1的ERK依赖性磷酸化。将TPO添加到UT 7-Mpl细胞和原代巨核细胞中诱导IEX-1的基因表达。促红细胞生成素（EPO）和粒细胞巨噬细胞集落刺激因子（GM-CSF）均不能激活UT 7-Mpl细胞中IEX-1基因的表达。诱导表达由IEX-1启动子的转录激活介导，并且需要位于-1068的AML 1结合位点。通过使用AML 1突变体和靶向内源性AML 1的shRNA实验，证实了AML 1直接参与IEX-1基因表达的调节。最后，TPO诱导IEX-1基因表达的能力被ERK激活剂MEK的特异性抑制剂U 0126抑制，并且显示TPO通过ERK依赖性磷酸化调节AML 1转录活性。总之，这些数据表明，AML 1在调节IEX-1表达中起作用，并且ERK依赖的AML 1磷酸化调节TPO介导的IEX-1活化。
The extracellular signal-regulated kinases (ERKs) are required for thrombopoietin (TPO) functions on hematopoietic cells, but the ERKS targets involved remain unknown. Here we show that the regulation of the immediate early gene X-1 (IEX-1), identified as an ERK substrate in response to TPO, was mediated by an ERK-dependent phosphorylation of AML1. The addition of TPO to UT7-Mpl cells and primary megakaryocytes induced gene expression of IEX-1. Neither erythropoietin (EPO) nor granulocyte macrophage-colony stimulating factor (GM-CSF) was able to activate IEX-1 gene expression in UT7-Mpl cells. The induced expression was mediated by a transcriptional activation of the IEX-1 promoter and required an AML1-binding site located at -1068. The direct involvement of AML1 in the regulation of IEX-1 gene expression was shown by both the use of AML1 mutants and by shRNA experiments targeting endogenous AML1. Finally, the ability of TPO to induce the IEX-1 gene expression was inhibited by U0126, a specific inhibitor of the ERKs activator MEK and AML1 transcriptional activity was shown to be modulated by TPO through ERK-dependent phosphorylation. Taken together, these data suggest that AML1 plays a role in modulating the IEX-1 expression and that the ERK-dependent AML1 phosphorylation regulates the TPO-mediated activation of IEX-1.