A novel variant in the 3' UTR of human SCN1A gene from a patient with Dravet syndrome decreases mRNA stability mediated by GAPDH's binding
A novel variant in the 3' UTR of human SCN1A gene from a patient with Dravet syndrome decreases mRNA stability mediated by GAPDH's binding
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DOI：
10.1007/s00439-014-1422-8
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
Long YS
中科院分区：
文献类型：
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作者：
Zeng T;Dong ZF;Liu SJ;Wan RP;Tang LJ;Liu T;Zhao QH;Shi YW;Yi YH;Liao WP;Long YS
SCN 1A基因编码的电压门控钠离子通道α-I亚基（Nav1.1）突变可引起多种癫痫，包括Dravet综合征（DS），一种严重且难治的癫痫。在DS患者中发现了大量的SCN 1A突变，导致Nav1.1功能丧失或截短，导致单倍不足效应，表明SCN 1A的确切表达水平对维持正常脑功能至关重要。在本研究中，我们确定了五种变体c。1025 T>C，c.* 1031 A>T，c.* 1739 C>T，c.* 1794 C>T和C。* DS患者SCN 1A 3 ′ UTR的1961 C>T。C.* 1025 T>C，c.* 1031 A>T和C.* 1794 C>T在不同物种间是保守的。在所有五个变体中，只有c.* 1794 C>T是一个新的变异体，改变了预测的3′ UTR的二级结构。我们还发现，甘油醛-3-磷酸脱氢酶（GAPDH）只与含有突变等位基因1794 U的3′ UTR序列结合，而不与野生型等位基因1794 C结合，这表明突变等位基因形成了一个新的GAPDH结合位点。功能分析表明，该变体通过影响由GAPDH结合介导的mRNA稳定性来负调节报告基因的表达，并且这种现象可以通过shRNA诱导的GAPDH敲低来逆转。这些结果提示GAPDH和3′-UTR变异体在转录后水平参与调控SCN 1A的表达，为进一步研究3′-UTR变异体与SCN 1A相关疾病的关系提供了重要线索。
Mutations in theSCN1Agene-encoding voltage-gated sodium channel α-I subunit (Nav1.1) cause various spectrum of epilepsies including Dravet syndrome (DS), a severe and intractable form. A large number ofSCN1Amutations identified from the DS patients lead to the loss of function or truncation of Nav1.1 that result in a haploinsufficiency effects, indicating that the exact expression level ofSCN1Ashould be essential to maintain normal brain function. In this study, we have identified five variants c.*1025T>C, c.*1031A>T, c.*1739C>T, c.*1794C>T and c.*1961C>T in theSCN1A3′ UTR in the patients with DS. The c.*1025T>C, c.*1031A>T and c.*1794C>T are conserved among different species. Of all the five variants, only c.*1794C>T is a novel variant and alters the predicted secondary structure of the 3′ UTR. We also show that glyceraldehyde-3-phosphate dehydrogenase (GAPDH) only binds to the 3′ UTR sequence containing the mutation allele 1794U but not the wild-type allele 1794C, indicating that the mutation allele forms a new GAPDH-binding site. Functional analyses show that the variant negatively regulates the reporter gene expression by affecting the mRNA stability that is mediated by GAPDH’s binding, and this phenomenon could be reversed by shRNA-induced GAPDH knockdown. These findings suggest that GAPDH and the 3′-UTR variant are involved in regulatingSCN1Aexpression at post-transcriptional level, which may provide an important clue for further investigating on the relationship between 3′-UTR variants andSCN1A-related diseases.