title: Chironomus tentans-repressor splicing factor represses SR protein function locally on pre-mRNA exons and is displaced at correct splice sites.
abstract: Chironomus tentans-repressor splicing factor (Ct-RSF) represses the activation of splicing by SR proteins in vitro. Ct-RSF colocalizes with the Ser-Arg-rich (SR) protein hrp45 in interchromatin granule clusters and coimmunoprecipitates with hrp45 in nuclear extracts. Ct-RSF and hrp45 can also interact directly in vitro. Ct-RSF and hrp45 are recruited together to transcribing genes and associate with growing pre-mRNAs. Ct-RSF and hrp45 colocalize at a large number of gene loci. Injection of anti-Ct-RSF antibodies into nuclei of living cells blocks association of both Ct-RSF and hrp45 with the growing pre-mRNA, whereas binding of U2 small nuclear ribonucleoprotein particle (snRNP) to the pre-mRNA is unaffected. On the intron-rich Balbiani ring (BR) 3 pre-mRNA, hrp45 as well as U1 and U2 snRNPs bind extensively, whereas relatively little Ct-RSF is present. In contrast, the BR1 and BR2 pre-mRNAs, dominated by exon sequences, bind relatively much Ct-RSF compared with hrp45 and snRNPs. Our data suggest that Ct-RSF represses SR protein function at exons and that the assembly of spliceosomes at authentic splice sites displaces Ct-RSF locally.
authors.affiliation: Department of Molecular Biology and Functional Genomics, Stockholm University, SE-106 91 Stockholm, Sweden.
authors.forename: Petra
authors.initials: P
authors.lastname: Björk
authors.forename: Ingela
authors.initials: I
authors.lastname: Wetterberg-Strandh
authors.forename: Göran
authors.initials: G
authors.lastname: Baurén
authors.forename: Lars
authors.initials: L
authors.lastname: Wieslander
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002683:Chironomidae / Q000235:genetics / Q000378:metabolism*; D005091:Exons / Q000235:genetics*; D011485:Protein Binding; D012322:RNA Precursors / Q000235:genetics* / Q000378:metabolism; D022821:RNA Splice Sites / Q000235:genetics*; D012326:RNA Splicing / Q000235:genetics*; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic / Q000235:genetics
chemical_list: D012322:RNA Precursors; D022821:RNA Splice Sites; D016601:RNA-Binding Proteins