Disruption of the splicing enhancer sequence within exon 27 of the dystrophin gene by a nonsense mutation induces partial skipping of the exon and is responsible for Becker muscular dystrophy
Disruption of the splicing enhancer sequence within exon 27 of the dystrophin gene by a nonsense mutation induces partial skipping of the exon and is responsible for Becker muscular dystrophy
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DOI：
10.1172/jci119757
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发表时间：
1997-11-01
影响因子：
15.9
通讯作者：
Matsuo, M
中科院分区：
文献类型：
--
作者：
Shiga, N;Takeshima, Y;Matsuo, M
无义突变诱导外显子跳变的机制尚未得到很好的阐明，我们现在报告了体外剪接研究的结果，揭示了外显子跳变的一个特殊例子是由于位于外显子内的剪接增强子序列的破坏，在日本Pecker肌营养不良症患者的肌营养不良蛋白基因中发现了一个无义突变（E1211X），这是由于27号外显子（G3839T）的第28个核苷酸的G到T翻转引起的。为了确定E1211X是如何诱导27号外显子跳变的，我们利用嵌合双性基因pre-mRNA在体外剪接系统中检测了27号外显子富含嘌呤区域的剪接增强子活性。含有G3839T的突变序列消除了该嵌合pre-mRNA上游内含子的野生型富嘌呤序列的剪接增强子活性。模拟第27号外显子富含嘌呤序列的人工多嘌呤寡核苷酸也显示出增强子活性，该活性被T核苷酸的引入所抑制。此外，当插入的T残基产生无义密码子时，剪接增强子活性受到更明显的抑制。这是第一个证据，表明含有无义突变的外显子的部分跳变是由于剪接增强子序列的破坏。
The mechanism of exon skipping induced by nonsense mutations has not been well elucidated, We now report results of in vitro splicing studies which disclosed that a particular example of exon skipping is due to disruption of a splicing enhancer sequence located within the exon, A nonsense mutation (E1211X) due to a G to T transversion at the 28th nucleotide of exon 27 (G3839T) was identified in the dystrophin gene of a Japanese Pecker muscular dystrophy case, Partial skipping of the exon resulted in the production of truncated dystrophin mRNA, although the consensus sequences for splicing at both ends of exon 27 were unaltered,To determine how E1211X induced exon 27 skipping, the splicing enhancer activity of purine-rich region within exon 27 was examined in an in vitro splicing system using chimeric doublesex gene pre-mRNA. The mutant sequence containing G3839T abolished splicing enhancer activity of the wild-type purine-rich sequence for the upstream intron in this chimeric pre-mRNA. An artificial polypurine oligonucleotide mimicking the purine-rich sequence of exon 27 also showed enhancer activity that was suppressed by the introduction of a T nucleotide. Furthermore, the splicing enhancer activity was more markedly inhibited when a nonsense codon was created by the inserted T residue, This is the first evidence that partial skipping of an exon harboring a nonsense mutation is due to disruption of a splicing enhancer sequence.