Larsen C Aaron, Howard Michael T
Department of Human Genetics, University of Utah, Salt Lake City, UT, United States.
Department of Human Genetics, University of Utah, Salt Lake City, UT, United States.
Neuromuscul Disord. 2014 Aug;24(8):693-706. doi: 10.1016/j.nmd.2014.05.006. Epub 2014 May 22.
Duchenne muscular dystrophy (DMD), a severe muscle-wasting disease, is caused by mutations in the DMD gene, which encodes for the protein dystrophin. Its regulation is of therapeutic interest as even small changes in expression of functional dystrophin can significantly impact the severity of DMD. While tissue-specific distribution and transcriptional regulation of several DMD mRNA isoforms has been well characterized, the post-transcriptional regulation of dystrophin synthesis is not well understood. Here, we utilize qRTPCR and a quantitative dual-luciferase reporter assay to examine the effects of isoform specific DMD 5' UTRs and the highly conserved DMD 3' UTR on mRNA abundance and translational control of gene expression in C2C12 cells. The 5' UTRs were shown to initiate translation with low efficiency in both myoblasts and myotubes. Whereas, two large highly conserved elements in the 3' UTR, which overlap the previously described Lemaire A and D regions, increase mRNA levels and enhance translation upon differentiation of myoblasts into myotubes. The results presented here implicate an important role for DMD UTRs in dystrophin expression and delineate the cis-acting elements required for the myotube-specific regulation of steady-state mRNA levels and translational enhancer activity found in the DMD 3' UTR.
杜兴氏肌营养不良症（DMD）是一种严重的肌肉萎缩疾病，由DMD基因突变引起，该基因编码抗肌萎缩蛋白。其调控具有治疗意义，因为即使功能性抗肌萎缩蛋白表达的微小变化也会显著影响DMD的严重程度。虽然几种DMD mRNA亚型的组织特异性分布和转录调控已得到充分表征，但抗肌萎缩蛋白合成的转录后调控尚不清楚。在这里，我们利用qRTPCR和定量双荧光素酶报告基因检测来研究亚型特异性DMD 5'UTR和高度保守的DMD 3'UTR对C2C12细胞中mRNA丰度和基因表达翻译控制的影响。结果表明，5'UTR在成肌细胞和肌管中均以低效率启动翻译。然而，3'UTR中的两个高度保守的大元件，与先前描述的勒梅尔A区和D区重叠，在成肌细胞分化为肌管时会增加mRNA水平并增强翻译。本文的结果表明DMD UTR在抗肌萎缩蛋白表达中起重要作用，并确定了DMD 3'UTR中肌管特异性调节稳态mRNA水平和翻译增强子活性所需的顺式作用元件。
