Dok-5 is involved in cardiomyocyte differentiation through PKB/FOXO3a pathway
Dok-5 is involved in cardiomyocyte differentiation through PKB/FOXO3a pathway
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Dok-5 通过 PKB/FOXO3a 途径参与心肌细胞分化
DOI：
10.1016/j.yjmcc.2009.09.015
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发表时间：
2009-12-01
影响因子：
5
通讯作者：
Peng, Xiaozhong
中科院分区：
文献类型：
--
作者：
Wen, Jianyan;Xia, Qing;Peng, Xiaozhong
胰岛素受体底物（IRS）家族在大脑细胞生长、信号传导和存活中起着重要作用。我们发现IRS6/Dok-5是IRS家族的一员，也表达在心脏中。P19CL6细胞在心肌细胞分化过程中，Dok-5表达水平显著升高。为了了解Dok-5基因在心肌细胞分化过程中的表达和调控机制，我们首先绘制了小鼠Dok-5基因的转录起始位点，并对其启动子区域进行了表征。对Dok-5启动子的截断和突变分析确定了抑制Dok-5启动子激活的叉头结合元件。FOXO3a和Dok-5在小鼠心脏中的共定位使FOXO3a成为Dok-5的转录调节因子。电泳迁移率转移和染色质免疫沉淀实验证实FOXO3a可以结合到Dok-5启动子上，并伴有FOXO3a从细胞核向细胞质的易位。FOXO3a过表达可抑制Dok-5启动子活性。通过siRNA沉默FOXO3a表达上调Dok-5表达，增强心肌细胞分化。此外，Dok-5 siRNA减弱心肌细胞分化。我们的研究结果首次证明了PI3K/PKB下游底物FOXO3a可以作为转录抑制因子抑制Dok-5的表达。Dok-5通过PI3K/PKB/FOXO3a信号通路参与心肌细胞分化。爱思唯尔公司2009年版权所有版权所有。
The insulin receptor substrate (IRS) family plays important roles in cellular growth, signaling, and survival in the brain. We identified IRS6/Dok-5, a member of the IRS family, also expressed in heart. Dok-5 expression level significantly increased during cardiomyocyte differentiation of P19CL6 cells. To understand the mechanism of Dok-5 gene expression and regulation during cardiomyocyte differentiation, we first mapped the transcription start site of the mouse Dok-5 gene and characterized its promoter regions. Truncation and mutation analysis of the Dok-5 promoter identified the forkhead binding element responsible for the repression of Dok-5 promoter activation. The co-localization of FOXO3a and Dok-5 in the mouse heart allows FOXO3a to be a transcriptional regulator of Dok-5. Electrophoretic mobility shift assay and chromatin immunoprecipitation assay confirmed that FOXO3a, could bind to the Dok-5 promoter, accompanied by FOXO3a translocation from the nucleus to cytoplasm. FOXO3a overexpression could inhibit Dok-5 promoter activity. Silencing FOXO3a expression by siRNA upregulated the expression of Dok-5 and enhanced cardiomyocyte differentiation. Moreover, Dok-5 siRNA attenuated cardiomyocyte differentiation. Our results provide the first evidence that FOXO3a, the PI3K/PKB downstream substrate, acts as a transcriptional repressor to inhibit the expression of Dok-5. Dok-5 is involved in cardiomyocyte differentiation by a PI3K/PKB/FOXO3a signaling pathway. Crown Copyright (C) 2009 Published by Elsevier Inc. All rights reserved.