Sequential recruitment of PCAF and BRG1 contributes to myogenin activation in 12-O-tetradecanoylphorbol-13-acetate-induced early differentiation of rhabdomyosarcoma-derived cells
Sequential recruitment of PCAF and BRG1 contributes to myogenin activation in 12-O-tetradecanoylphorbol-13-acetate-induced early differentiation of rhabdomyosarcoma-derived cells
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DOI：
10.1074/jbc.m609448200
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发表时间：
2007-06-29
影响因子：
4.8
通讯作者：
Shen, Yu-fei
中科院分区：
文献类型：
--
作者：
Li, Zhao-yong;Yang, Jun;Shen, Yu-fei
已知肌原素及其上游调节因子MyoD是肌源性细胞分化所必需的。虽然它们都可以在横纹肌肉瘤来源的RD细胞中表达，但这些细胞不能经历全面的终末肌源性分化。12- o - tetradecanoylphorol -13-acetate （TPA）已被发现在诱导RD细胞分化中起作用，但其机制尚不完全清楚。通过定量实时染色质免疫沉淀和实时逆转录- pcr启动子活性测定，我们研究了tpa诱导RD细胞分化过程中肌原素基因的激活机制。我们已经证明，组蛋白乙酰转移酶PCAF和SWI/SNF染色质重塑复合体的atp酶亚基BRG1依次被招募到肌原基因的启动子上。PCAF和BRG1也参与了肌原蛋白基因的激活。此外，我们发现p38丝裂原活化蛋白激酶是tpa介导的肌原诱导中BRG1募集所必需的。我们提出，在tpa诱导的RD细胞早期分化中，肌原素的诱导有两个不同的激活步骤：1)早期步骤需要PCAF活性使核心组蛋白和MyoD乙酰化以启动肌原素基因表达；2)后期步骤需要p38依赖的SWI/SNF重塑复合体活性为肌原素的诱导提供一个开放的构象。我们的研究揭示了表观遗传调控在tpa诱导的RD细胞分化中的重要作用，并为未来横纹肌肉瘤的治疗提供了潜在的药物靶点。
Myogenin and its upstream regulator MyoD are known to be required for myogenic cell differentiation. Although both of them can be expressed in rhabdomyosarcoma-derived RD cells, the cells are unable to undergo full-scale terminal myogenic differentiation. 12-O-Tetradecanoylphorbol-13-acetate (TPA) has been found to be functional in the induction of RD cell differentiation, whereas its mechanism is not fully understood. By using quantitative real-time-based chromatin immunoprecipitation and real-time reverse transcription-PCR-based promoter activity assays, we examined the activation mechanism of the myogenin gene during TPA-induced differentiation of the RD cells. We have shown that a histone acetyltransferase PCAF and ATPase subunit BRG1 of the SWI/SNF chromatin remodeling complex are sequentially recruited to the promoter of the myogenin gene. Both PCAF and BRG1 are also involved in the activation of the myogenin gene. In addition, we have found that the p38 mitogen-activated protein kinase is required for BRG1 recruitment in TPA-mediated myogenin induction. We propose that there are two distinct activation steps for the induction of myogenin in TPA-induced early differentiation of RD cells: 1) an early step that requires PCAF activity to acetylate core histones and MyoD to initiate myogenin gene expression, and 2) a later step that requires p38-dependent activity of the SWI/SNF remodeling complex to provide an open conformation for the induction of myogenin. Our studies reveal an essential role for epigenetic regulation in TPA-induced differentiation of RD cells and provide potential drug targets for future treatment of the rhabdomyosarcoma.