title: Identification of truncated forms of U1 snRNA reveals a novel RNA degradation pathway during snRNP biogenesis.
abstract: The U1 small nuclear ribonucleoprotein (snRNP) plays pivotal roles in pre-mRNA splicing and in regulating mRNA length and isoform expression; however, the mechanism of U1 snRNA quality control remains undetermined. Here, we describe a novel surveillance pathway for U1 snRNP biogenesis. Mass spectrometry-based RNA analysis showed that a small population of SMN complexes contains truncated forms of U1 snRNA (U1-tfs) lacking the Sm-binding site and stem loop 4 but containing a 7-monomethylguanosine 5' cap and a methylated first adenosine base. U1-tfs form a unique SMN complex, are shunted to processing bodies and have a turnover rate faster than that of mature U1 snRNA. U1-tfs are formed partly from the transcripts of U1 genes and partly from those lacking the 3' box elements or having defective SL4 coding regions. We propose that U1 snRNP biogenesis is under strict quality control: U1 transcripts are surveyed at the 3'-terminal region and U1-tfs are diverted from the normal U1 snRNP biogenesis pathway.
authors: Department of Applied Biological Science, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan, Metabolome Division, Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Sanbancho 5, Chiyoda-ku, Tokyo 102-0075, Japan, Department of Chemistry, Graduate School of Sciences and Engineering, Tokyo Metropolitan University, 1-1 Minamiosawa, Hachiouji-shi, Tokyo 192-0397, Japan, Department of Bioengineering, United Graduate School of Agriculture, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 183-8509, Japan and Biomolecular Characterization Team, RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
authors: Hideaki
authors: H
authors: Ishikawa
authors: Yuko
authors: Y
authors: Nobe
authors: Keiichi
authors: K
authors: Izumikawa
authors: Harunori
authors: H
authors: Yoshikawa
authors: Naoki
authors: N
authors: Miyazawa
authors: Goro
authors: G
authors: Terukina
authors: Natsuki
authors: N
authors: Kurokawa
authors: Masato
authors: M
authors: Taoka
authors: Yoshio
authors: Y
authors: Yamauchi
authors: Hiroshi
authors: H
authors: Nakayama
authors: Toshiaki
authors: T
authors: Isobe
authors: Nobuhiro
authors: N
authors: Takahashi
mesh_terms: D000241:Adenosine / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D006151:Guanosine / Q000031:analogs & derivatives / Q000032:analysis; D013058:Mass Spectrometry; D008745:Methylation; D020871:RNA Stability; D012342:RNA, Small Nuclear / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017411:Ribonucleoproteins, Small Nuclear / Q000378:metabolism*; D055532:SMN Complex Proteins / Q000378:metabolism
chemical_list: D012342:RNA, Small Nuclear; D017411:Ribonucleoproteins, Small Nuclear; D055532:SMN Complex Proteins; C405483:U1 small nuclear RNA; D006151:Guanosine; C016578:7-methylguanosine; D000241:Adenosine