Common Pathological Mutations in PQBP1 Induce Nonsense-Mediated mRNA Decay and Enhance Exclusion of the Mutant Exon
Common Pathological Mutations in PQBP1 Induce Nonsense-Mediated mRNA Decay and Enhance Exclusion of the Mutant Exon
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DOI：
10.1002/humu.21146
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发表时间：
2010-01-01
期刊：
影响因子：
3.9
通讯作者：
Kalscheuer, Vera M.
中科院分区：
文献类型：
--
作者：
Musante, Luciana;Kunde, Stella-Amrei;Kalscheuer, Vera M.
聚谷氨酰胺结合蛋白1 （PQBP1）基因在x连锁智力低下（XLMR）中起重要作用。迄今为止已知的13个PQBP1突变中有9个影响外显子4的AG六聚体，并导致引入过早终止密码子（ptc）的帧移。然而，这组患者的表型是可变的。为了研究这些PQBP1突变的病理学，我们评估了它们对mRNA和蛋白表达的影响。rt - pcr显示突变。携带ptc的PQBP1 mRNA特异性减少，ptc可以通过阻断翻译部分恢复，从而表明无义介导的mRNA衰变途径的作用。此外，这些突变导致PQBP1转录本跳过外显子4的水平改变，这可能是通过无义相关剪接改变（NAS）改变重要剪接基序的结果。这一假设得到了野生型和突变型PQBP1小基因转染实验的支持。此外，我们发现截断的PQBP1蛋白确实存在于患者体内。值得注意的是，AG六聚体插入/缺失突变的患者表达PQBP1异构体的水平显著增加，该异构体很可能是由没有外显子4的转录本编码的，这在mRNA水平上证实了研究结果。我们的研究为PQBP1相关XLMR疾病发病机制的早期事件提供了重要的见解。[j], 2010。(C) 2009 Wiley-Liss, Inc。
The polyglutamine binding protein 1 (PQBP1) gene plays an important role in X-linked mental retardation (XLMR). Nine of the thirteen PQBP1 mutations known to date affect the AG hexamer in exon 4 and cause frameshifts introducing premature termination codons (PTCs). However, the phenotype in this group of patients is variable. To investigate the pathology of these PQBP1 mutations, We evaluated their consequences on mRNA and protein expression. RT-PCRs revealed mutation. specific reduction of PQBP1 mRNAs carrying the PTCs that can be partially restored by blocking translation, thus indicating a role for the nonsense-mediated mRNA decay pathway. In addition, these mutations resulted in altered levels of PQBP1 transcripts that skipped exon 4, probably as a result of altering important splicing motifs via nonsense-associated altered splicing (NAS). This hypothesis is supported by transfection experiments using wild-type and mutant PQBP1 minigenes. Moreover, we show that a truncated PQBP1 protein is indeed present in the patients. Remarkably, patients with insertion/deletion mutations in the AG hexamer express significantly increased levels of a PQBP1 isoform, which is very likely encoded by the transcripts without exon 4, confirming the findings at the mRNA level. Our study provides significant insight into the early events contributing to the pathogenesis of the PQBP1 related XLMR disease. Hum Mutat 31:90-98, 2010. (C) 2009 Wiley-Liss, Inc.