title: MBNL1 binds GC motifs embedded in pyrimidines to regulate alternative splicing.
abstract: Muscleblind-like 1 (MBNL1) regulates alternative splicing and is a key player in the disease mechanism of myotonic dystrophy (DM). In DM, MBNL1 becomes sequestered to expanded CUG/CCUG repeat RNAs resulting in splicing defects, which lead to disease symptoms. In order to understand MBNL1's role in both the disease mechanism of DM and alternative splicing regulation, we sought to identify its RNA-binding motif. A doped SELEX was performed on a known MBNL1-binding site. After five rounds of SELEX, MBNL1 selected pyrimidine-rich RNAs containing YGCY motifs. Insertion of multiple YGCY motifs into a normally MBNL1-independent splicing reporter was sufficient to promote regulation by MBNL1. MBNL1 was also shown to regulate the splicing of exon 22 in the ATP2A1 pre-mRNA, an exon mis-spliced in DM, via YGCY motifs. A search for YGCY motifs in 24 pre-mRNA transcripts that are mis-spliced in DM1 patients revealed an interesting pattern relative to the regulated exon. The intronic regions upstream of exons that are excluded in normal tissues relative to DM1, are enriched in YGCY motifs. Meanwhile, the intronic regions downstream of exons that are included in normal tissues relative to DM1, are enriched in YGCY motifs.
authors.affiliation: Department of Chemistry and Institute of Molecular Biology, University of Oregon, Eugene, OR 97401, USA.
authors.forename: Emily S
authors.initials: ES
authors.lastname: Goers
authors.forename: Jamie
authors.initials: J
authors.lastname: Purcell
authors.forename: Rodger B
authors.initials: RB
authors.lastname: Voelker
authors.forename: Devika P
authors.initials: DP
authors.lastname: Gates
authors.forename: J Andrew
authors.initials: JA
authors.lastname: Berglund
mesh_terms: D017398:Alternative Splicing; D001665:Binding Sites; D005091:Exons; D020862:GC Rich Sequence; D017930:Genes, Reporter; D006367:HeLa Cells; D006801:Humans; D007438:Introns; D009136:Muscular Dystrophies / Q000235:genetics; D009154:Mutation; D011743:Pyrimidines / Q000032:analysis; D012322:RNA Precursors / Q000737:chemistry* / Q000378:metabolism; D012333:RNA, Messenger / Q000737:chemistry* / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism*; D052156:SELEX Aptamer Technique; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000235:genetics; D017423:Sequence Analysis, RNA
chemical_list: C493663:MBNL1 protein, human; D011743:Pyrimidines; D012322:RNA Precursors; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; C506943:ATP2A1 protein, human