Premature termination codons in PRPF31 cause retinitis pigmentosa via haploinsufficiency due to nonsense-mediated mRNA decay
Premature termination codons in PRPF31 cause retinitis pigmentosa via haploinsufficiency due to nonsense-mediated mRNA decay
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DOI：
10.1172/jci34211
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发表时间：
2008-04-01
影响因子：
15.9
通讯作者：
Rivolta, Carlo
中科院分区：
文献类型：
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作者：
Frio, Thomas Rio;Wade, Nicholas M.;Rivolta, Carlo
编码mRNA剪接因子PRPF 31的基因的显性突变导致视网膜色素变性，这是一种遗传性视网膜变性。这些突变中的大多数以导致提前终止密码子的DNA变化为特征。我们研究了来自9例显性视网膜色素变性患者的细胞系中6种不同的PRPF 31突变，以单碱基取代或微缺失为代表。这些突变中的5个导致提前终止密码子，1个导致外显子2的跳跃。等位基因特异性测量PRPF 31转录本显示突变等位基因的表达强烈减少。结果，总PRPF 31蛋白丰度降低，并且没有检测到截短的蛋白。存在的全长PRPF 31的亚核定位不受影响。阻断无义介导的mRNA衰变显著恢复了突变型PRPF 31 mRNA的量，但没有恢复突变型蛋白质的合成，即使与蛋白质降解途径的抑制剂结合。我们的研究结果表明，大多数PRPF31突变最终导致无效等位基因通过激活的监视机制，使突变的mRNA，并可能，蛋白质。此外，这些数据提供了令人信服的证据，PRPF 31突变的致病作用可能是由于单倍不足，而不是获得功能。
Dominant mutations in the gene encoding the mRNA splicing factor PRPF31 cause retinitis pigmentosa, a hereditary form of retinal degeneration. Most of these mutations are characterized by DNA changes that lead to premature termination codons. We investigated 6 different PRPF31 mutations, represented by single-base substitutions or microdeletions, in cell lines derived from 9 patients with dominant retinitis pigmentosa. Five of these mutations lead to premature termination codons, and 1 leads to the skipping of exon 2. Allele-specific measurement of PRPF31 transcripts revealed a strong reduction in the expression of mutant alleles. As a consequence, total PRPF31 protein abundance was decreased, and no truncated proteins were detected. Subnuclear localization of the full-length PRPF31 that was present remained unaffected. Blocking nonsense-mediated mRNA decay significantly restored the amount of mutant PRPF31 mRNA but did not restore the synthesis of mutant proteins, even in conjunction with inhibitors of protein degradation pathways. Our results indicate that most PRPF31 mutations ultimately result in null alleles through the activation of surveillance mechanisms that inactivate mutant mRNA and, possibly, proteins. Furthermore, these data provide compelling evidence that the pathogenic effect of PRPF31 mutations is likely due to haploinsufficiency rather than to gain of function.