Quality control of assembly-defective U1 snRNAs by decapping and 5'-to-3' exonucleolytic digestion

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 111; no. 32; p. 11582
• Main Authors: Shukla, Siddharth, Parker, Roy
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 12.08.2014; National Acad Sciences
• Series: PNAS Plus
• Subjects: Animals; Biological Sciences; Cells; Endoribonucleases - antagonists & inhibitors; Endoribonucleases - genetics; Endoribonucleases - metabolism; Gene Knockdown Techniques; HeLa Cells; Humans; Mice; Models, Biological; Mutation; Neurons; NIH 3T3 Cells; PNAS Plus; PNAS Plus: Significance Statements; Proteins; Quality Control; Ribonucleic acid; Ribonucleoproteins, Small Nuclear - chemistry; Ribonucleoproteins, Small Nuclear - metabolism; RNA; RNA Splicing; RNA Stability - genetics; RNA, Fungal - genetics; RNA, Fungal - metabolism; RNA, Small Nuclear - genetics; RNA, Small Nuclear - metabolism; Survival of Motor Neuron 1 Protein - antagonists & inhibitors; Survival of Motor Neuron 1 Protein - genetics; Survival of Motor Neuron 1 Protein - metabolism; Yeast
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1412614111

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.