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标题：Quality control of assembly-defective U1 snRNAs by decapping and 5′-to-3′ exonucleolytic digestion
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作者：Siddharth Shukla ; Roy Parker
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2014
卷号：111
期号：32
页码：E3277-E3286
DOI：10.1073/pnas.1412614111
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The accurate biogenesis of RNA-protein complexes is a key aspect of eukaryotic cells. Defects in Sm protein complex binding to snRNAs are known to reduce levels of snRNAs, suggesting an unknown quality control system for small nuclear ribonucleoprotein (snRNP) assembly. snRNA quality control may also be relevant in spinal muscular atrophy, which is caused by defects in the survival motor neuron (SMN)1 gene, an assembly factor for loading the Sm complex on snRNAs and, when severely reduced, can lead to reduced levels of snRNAs and splicing defects. To determine how assembly-defective snRNAs are degraded, we first demonstrate that yeast U1 Sm-mutant snRNAs are degraded either by Rrp6- or by Dcp2-dependent decapping/5'-to-3' decay. Knockdown of the decapping enzyme DCP2 in mammalian cells also increases the levels of assembly-defective snRNAs and suppresses some splicing defects seen in SMN-deficient cells. These results identify a conserved mechanism of snRNA quality control, and also suggest a general paradigm wherein the phenotype of an "RNP assembly disease" might be suppressed by inhibition of a competing RNA quality control mechanism.