title: SMU-2 and SMU-1, Caenorhabditis elegans homologs of mammalian spliceosome-associated proteins RED and fSAP57, work together to affect splice site choice.
abstract: Mutations in the Caenorhabditis elegans gene smu-2 suppress mec-8 and unc-52 mutations. It has been proposed that MEC-8 regulates the alternative splicing of unc-52 transcripts, which encode the core protein of perlecan, a basement membrane proteoglycan. We show that mutation in smu-2 leads to enhanced accumulation of transcripts that skip exon 17, but not exon 18, of unc-52, which explains our finding that smu-2 mutations suppress the uncoordination conferred by nonsense mutations in exon 17, but not in exon 18, of unc-52. We conclude that smu-2 encodes a ubiquitously expressed nuclear protein that is 40% identical to the human RED protein, a component of purified spliceosomes. The effects of smu-2 mutation on both unc-52 pre-mRNA splicing and the suppression of mec-8 and unc-52 mutant phenotypes are indistinguishable from the effects of mutation in smu-1, a gene that encodes a protein that is 62% identical to human spliceosome-associated protein fSAP57. We provide evidence that SMU-2 protects SMU-1 from degradation in vivo. In vitro and in vivo coimmunoprecipitation experiments indicate that SMU-2 and SMU-1 bind to each other. We propose that SMU-2 and SMU-1 function together to regulate splice site choice in the pre-mRNAs of unc-52 and other genes.
authors.affiliation: Department of Genetics, Cell Biology and Development, University of Minnesota, 6-160 Jackson Hall, 321 Washington Avenue SE, Minneapolis, MN 55455, USA.
authors.forename: Angela K
authors.initials: AK
authors.lastname: Spartz
authors.forename: Robert K
authors.initials: RK
authors.lastname: Herman
authors.forename: Jocelyn E
authors.initials: JE
authors.lastname: Shaw
mesh_terms: D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D015153:Blotting, Western; D017173:Caenorhabditis elegans; D029742:Caenorhabditis elegans Proteins / Q000235:genetics* / Q000502:physiology; D002467:Cell Nucleus / Q000378:metabolism; D003001:Cloning, Molecular; D005091:Exons; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008164:Luminescent Proteins / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism* / Q000502:physiology; D010641:Phenotype; D020161:Physical Chromosome Mapping; D011233:Precipitin Tests; D012313:RNA / Q000378:metabolism; D012330:RNA, Double-Stranded / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012260:Ribonucleases / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D017381:Spliceosomes / Q000378:metabolism*
chemical_list: D029742:Caenorhabditis elegans Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008164:Luminescent Proteins; D009687:Nuclear Proteins; D012330:RNA, Double-Stranded; D012333:RNA, Messenger; C488500:SMU-2 protein, C elegans; C432686:Smu-1 protein, C elegans; D049452:Green Fluorescent Proteins; D012313:RNA; D012260:Ribonucleases