Activated Raf inhibits avian myogenesis through a MAPK-dependent mechanism
Activated Raf inhibits avian myogenesis through a MAPK-dependent mechanism
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DOI：
10.1038/sj.onc.1202907
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发表时间：
1999-09-16
期刊：
影响因子：
8
通讯作者：
Johnson, SE
中科院分区：
文献类型：
--
作者：
Dorman, CM;Johnson, SE
Ras致癌形式的慢性过度表达是骨骼肌发生的有效抑制剂。然而，介导Ras对肌源性分化的抑制作用的细胞内信号通路尚未被确定。我们研究了Raf-mediated信号转导作为禽类肌肉发生调节剂的作用。Raf过表达对成肌细胞和成熟肌细胞均产生明显影响。最值得注意的是，过表达Raf组成型活性形式（RCAS-Raf CAAX或RCAS-Raf BXB）的鸡胚成肌细胞不能形成肌原性培养物所特有的大的多核肌纤维。虽然在RCAS-Raf BXB和RCAS-Raf CAAX感染的培养物中残留的肌纤维是明显的，但这些纤维具有萎缩表型。改变的形态不是肌核细胞周期重新启动的结果，也不是由于凋亡。此外，由于明显的MAPK活性，错误表达Raf BXB的单核成肌细胞是分化缺陷的。补充的培养基与MAPK激酶（MEK）抑制剂，PD 98059，引起逆转的表型，并允许形成多核肌纤维的水平与对照组相当。我们的研究结果表明Raf/MEK/MAPK轴在鸡成肌细胞中是完整的，并且该信号级联的持续激活抑制肌发生。
Chronic overexpression of the oncogenic form of Ras is a potent inhibitor of skeletal myogenesis. However, the intracellular signaling pathways that mediate the repressive actions of Ras on myogenic differentiation have yet to be identified. We examined the role of Raf-mediated signaling as a modulator of avian myogenesis. Raf overexpression elicited pronounced effects on both myoblasts and mature myocytes. Most notably, the embryonic chick myoblasts overexpressing a constitutively active form of Raf (RCAS-Raf CAAX or RCAS-Raf BXB) fail to form the large multinucleated myofibers characteristic of myogenic cultures. While residual myofibers were apparent in the RCAS-Raf BXB and RCAS-Raf CAAX infected cultures, these fibers had an atrophic phenotype, The altered morphology is not a result of reinitiation of the myonuclei cell cycle nor is it due to apoptosis, Furthermore, the mononucleated myoblasts misexpressing Raf BXB are differentiation-defective due to overt MAPK activity. Supplementation of the culture media with the MAPK kinase (MEK) inhibitor, PD98059, caused a reversal of the phenotype and allowed the formation of multinucleated myofibers at levels comparable to controls. Our results indicate that the Raf/MEK/MAPK axis is intact in chick myoblasts and that persistent activation of this signaling cascade is inhibitory to myogenesis.