An Ultraconserved Element (UCE) controls homeostatic splicing of ARGLU1 mRNA.
An Ultraconserved Element (UCE) controls homeostatic splicing of ARGLU1 mRNA.
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DOI：
10.1093/nar/gkw1140
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发表时间：
2017-04-07
影响因子：
14.9
通讯作者：
Carmichael GG
中科院分区：
文献类型：
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作者：
Pirnie SP;Osman A;Zhu Y;Carmichael GG
富含精氨酸和谷氨酸的蛋白质1（ARGLU 1）是一种功能知之甚少的蛋白质，但可能在转录和前mRNA剪接中起作用。我们证明，ARGLU 1基因表达至少三种不同的RNA剪接异构体-一个完全剪接的异构体编码的蛋白质，一个异构体含有保留内含子被拘留在细胞核中，和一个异构体含有一个选择性外显子，靶向转录无义介导的衰变。此外，ARGLU 1包含一个长的，高度进化保守的序列，称为超保守元件（UCE），它位于保留内含子内，并与选择性外显子重叠。在报告基因小基因中或通过使用CRISPR/Cas9的基因组背景中的随机突变操纵UCE，改变了剪接模式。此外，ARGLU 1蛋白的过表达改变了内源性ARGLU 1 mRNA的剪接，导致保留内含子同种型和无义介导的衰变敏感同种型的增加以及完全剪接同种型的减少。结合显示功能性蛋白质敲除使剪接向完全剪接异构体转移的数据，我们的数据与在选择性外显子处组装的非生产性剪接复合物导致低效剪接和内含子保留的模型一致。
Arginine and Glutamate-Rich protein 1 (ARGLU1) is a protein whose function is poorly understood, but may act in both transcription and pre-mRNA splicing. We demonstrate that the ARGLU1 gene expresses at least three distinct RNA splice isoforms – a fully spliced isoform coding for the protein, an isoform containing a retained intron that is detained in the nucleus, and an isoform containing an alternative exon that targets the transcript for nonsense mediated decay. Furthermore, ARGLU1 contains a long, highly evolutionarily conserved sequence known as an Ultraconserved Element (UCE) that is within the retained intron and overlaps the alternative exon. Manipulation of the UCE, in a reporter minigene or via random mutations in the genomic context using CRISPR/Cas9, changed the splicing pattern. Further, overexpression of the ARGLU1 protein shifted the splicing of endogenous ARGLU1 mRNA, resulting in an increase in the retained intron isoform and nonsense mediated decay susceptible isoform and a decrease in the fully spliced isoform. Taken together with data showing that functional protein knockout shifts splicing toward the fully spliced isoform, our data are consistent with a model in which unproductive splicing complexes assembled at the alternative exon lead to inefficient splicing and intron retention.