Mutant DMPK 3'-UTR transcripts disrupt C2C12 myogenic differentiation by compromising MyoD.
Mutant DMPK 3'-UTR transcripts disrupt C2C12 myogenic differentiation by compromising MyoD.
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DOI：
10.1083/jcb.200206020
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发表时间：
2002-11-11
期刊：
影响因子：
--
通讯作者：
Mahadevan MS
中科院分区：
文献类型：
--
作者：
Amack JD;Reagan SR;Mahadevan MS
强直性肌营养不良（DM）是由两个相似的非编码重复扩增突变（DM 1和DM 2）引起的。据认为，这两种突变产生的致病RNA分子，积累在核灶。DM 1突变是强直性肌营养不良症蛋白激酶（DMPK）3′非翻译区（3′-UTR）的CTG扩增。在细胞培养模型中，含有（CUG）200 DMPK 3′-UTR的突变体转录物破坏C2 C12成肌细胞分化;这一表型与在DM 1患者肌肉来源的成肌细胞培养物中观察到的表型相似。在这里，我们使用我们的细胞培养模型来研究突变的3 '-UTR RNA如何破坏分化。我们发现MyoD蛋白水平在表达突变DMPK 3′-UTR转录物的细胞中受到损害。MyoD是肌肉再生过程中成肌细胞分化所需的转录因子，通过结合E-box激活分化特异性基因。在分化条件下，在前6小时内，表达突变体3′-UTR RNA的成肌细胞中MyoD水平显著降低。这种减少与在对启动分化至关重要的时间点的钝化的E-box介导的基因表达相关。重要的是，恢复MyoD水平挽救了分化缺陷。我们的结论是突变的DMPK 3′-UTR转录物通过将MyoD水平降低到激活分化程序所需的阈值以下来破坏成肌细胞分化。
Myotonic dystrophy (DM) is caused by two similar noncoding repeat expansion mutations (DM1 and DM2). It is thought that both mutations produce pathogenic RNA molecules that accumulate in nuclear foci. The DM1 mutation is a CTG expansion in the 3′ untranslated region (3′-UTR) of dystrophia myotonica protein kinase (DMPK). In a cell culture model, mutant transcripts containing a (CUG)200 DMPK 3′-UTR disrupt C2C12 myoblast differentiation; a phenotype similar to what is observed in myoblast cultures derived from DM1 patient muscle. Here, we have used our cell culture model to investigate how the mutant 3′-UTR RNA disrupts differentiation. We show that MyoD protein levels are compromised in cells that express mutant DMPK 3′-UTR transcripts. MyoD, a transcription factor required for the differentiation of myoblasts during muscle regeneration, activates differentiation-specific genes by binding E-boxes. MyoD levels are significantly reduced in myoblasts expressing the mutant 3′-UTR RNA within the first 6 h under differentiation conditions. This reduction correlates with blunted E-box–mediated gene expression at time points that are critical for initiating differentiation. Importantly, restoring MyoD levels rescues the differentiation defect. We conclude that mutant DMPK 3′-UTR transcripts disrupt myoblast differentiation by reducing MyoD levels below a threshold required to activate the differentiation program.
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