Activation of the β myosin heavy chain promoter by MEF-2D, MyoD, p300, and the calcineurin/NFATc1 pathway
Activation of the β myosin heavy chain promoter by MEF-2D, MyoD, p300, and the calcineurin/NFATc1 pathway
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DOI：
10.1002/jcp.20916
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发表时间：
2007-04-01
影响因子：
5.6
通讯作者：
Scheibe, Renate J.
中科院分区：
文献类型：
--
作者：
Meissner, Joachim D.;Umeda, Patrick K.;Scheibe, Renate J.
钙是骨骼肌细胞内信号传导的关键元素。细胞内钙水平的变化被认为介导肌纤维类型从快到慢的转变。参与成人肌肉基因调控的因素之一是活化 T 细胞 (NFAT) 同种型 c 1 的核因子，其通过钙/钙调蛋白依赖性磷酸酶钙调神经磷酸酶的去磷酸化促进其核转位。在这里，我们报道，主要表达快速型 MyHCII 蛋白的分化 C2C12 肌管在钙离子载体处理后经历快向慢速转化，其中几个转录因子和转录共激活因子协同作用，上调慢速肌球蛋白重链 (MyHC) β 启动子。瞬时转染测定表明，钙调神经磷酸酶/NFATcI 信号通路对于 C2C12 肌管转化过程中 MyHC beta 启动子激活至关重要，但不足以完全快速抑制 MyHCIId/x 启动子。与 NFATc 1 一起，肌细胞增强因子 2D (MEF-2D) 和生肌转录因子 MyoD 以钙调神经磷酸酶依赖性方式反式激活钙离子载体处理的肌管中的 MyHCP 启动子。为了阐明参与调节 MyHCO 基因表达的机制，我们分析了 -2.4-kb MyHCO 启动子构建体的顺式调节元件。使用电泳迁移率变动分析 (EMSA)、染色质免疫沉淀分析 (ChIP) 和核复合物共免疫沉淀 (NCcolP) 分析，我们证明了钙离子载体诱导的 NFATc I 与邻近 MyoD 结合 E-box 的 NFAT 共有位点的结合。在各自的结合位点，NFATcI 和 MyoD 都招募转录共激活因子 p300，反过来，MEF-2D 与 MyoD 复合物结合。钙离子载体对 MyHC beta 启动子的影响被证明是钙调神经磷酸酶依赖性的。总之，我们的研究结果表明，NFATc1、MyoD、MEF-21D 和 p300 以钙调神经磷酸酶依赖性方式诱导钙离子载体激活 β MyHC 启动子。
Calcium is a key element in intracellular signaling in skeletal muscle. Changes in intracellular calcium levels are thought to mediate the fast-to-slow transformation of muscle fiber type. One factor implicated in gene regulation in adult muscle is the nuclear factor of activated T-cells (NFAT) isoform c 1, whose dephosphorylation by the calcium/calmodulin-dependent phosphatase calcineurin facilitates its nuclear translocation. Here, we report that differentiated C2C12 myotubes predominantly expressing fast-type MyHCII protein undergo fast-to-slow transformation following calcium-ionophore treatment, with several transcription factors and a transcriptional coactivator acting in concert to upregulate the slow myosin heavy chain (MyHC) beta promoter. Transient transfection assays demonstrated that the calcineurin/NFATcI signaling pathway is essential for MyHC beta promoter activation during transformation of C2C12 myotubes but is not sufficient for complete fast MyHCIId/x promoter inhibition. Along with NFATc 1, myocyte enhancer factor-2D (MEF-2D) and the myogenic transcription factor MyoD transactivated the MyHCP promoter in calcium-ionophore-treated myotubes in a calcineurin-dependent manner. To elucidate the mechanism involved in regulating MyHCO gene expression, we analyzed the -2.4-kb MyHCO promoter construct for cis-regulatory elements. Using electrophoretic mobility shift assays (EMSAs), chromatin immunoprecipitation assays (ChIP), and nuclear complex coimmunoprecipitation (NCcolP) assays, we demonstrated calcium-ionophore-induced binding of NFATc I to a NFAT consensus site adjacert to a MyoD-binding E-box. At their respective binding sites, both NFATcI and MyoD recruited the transcriptional coactivator p300, and in turn, MEF-2D bound to the MyoD complex. The calcium-ionophore-incluced effects on the MyHC beta promoter were shown to be calcineurin-dependent. Together, our findings demonstrate calcium-ionophore-induced activation of the beta MyHC promoter by NFATc1, MyoD, MEF-21D, and p300 in a calcineurin-dependent manner.