Project description:The RNA helicase BRR2 (SNRNP200) is one of the key remodeling factors of the spliceosome. Here we show its direct interaction with C9ORF78, a poorly characterized protein predicted to be largely intrinsically disordered. We present cryo-EM structures showing how C9ORF78 and the spliceosomal B-complex protein FBP21 wrap around the C-terminal helicase cassette of BRR2 and that binding of the two proteins is mutually exclusive. C9ORF78 associates with the spliceosome, as we confirm via proteomics and RNA UV-crosslinking. An siRNA mediated C9ORF78 knockdown reveals changes in alternative splicing of specific target pre-mRNAs, which in part depend on its interaction with BRR2. In particular, C9ORF78 regulates a substantial number of alternative 3’ splice sites, which might be facilitated through an additional interaction with human PRP22 (DHX8).
Project description:The RNA helicase BRR2 (SNRNP200) is one of the key remodeling factors of the spliceosome. Here we show its direct interaction with C9ORF78, a poorly characterized protein predicted to be largely intrinsically disordered. We present cryo-EM structures showing how C9ORF78 and the spliceosomal B-complex protein FBP21 wrap around the C-terminal helicase cassette of BRR2 and that binding of the two proteins is mutually exclusive. C9ORF78 associates with the spliceosome, as we confirm via proteomics and RNA UV-crosslinking. An siRNA mediated C9ORF78 knockdown reveals changes in alternative splicing of specific target pre-mRNAs, which in part depend on its interaction with BRR2. In particular, C9ORF78 regulates a substantial number of alternative 3’ splice sites, which might be facilitated through an additional interaction with human PRP22 (DHX8).
Project description:The RNA helicase BRR2 (SNRNP200) is one of the key remodeling factors of the spliceosome. Here we show its direct interaction with C9ORF78, a poorly characterized protein predicted to be largely intrinsically disordered. We present cryo-EM structures showing how C9ORF78 and the spliceosomal B-complex protein FBP21 wrap around the C-terminal helicase cassette of BRR2 and that binding of the two proteins is mutually exclusive. C9ORF78 associates with the spliceosome, as we confirm via proteomics and RNA UV-crosslinking. An siRNA mediated C9ORF78 knockdown reveals changes in alternative splicing of specific target pre-mRNAs, which in part depend on its interaction with BRR2. In particular, C9ORF78 regulates a substantial number of alternative 3’ splice sites, which might be facilitated through an additional interaction with human PRP22 (DHX8).
Project description:Alternative splicing of pre-mRNA is a prominent mechanism to generate protein diversity, yet its regulation is poorly understood. Here, we demonstrate a direct role for histone modifications in alternative splicing. We find distinctive histone modification signatures which correlate with splicing outcome in a set of human genes. Modulation of histone modifications causes splice site switching. The mechanism for histone-mediated splice site selection involves a histone mark which is read by a chromatin protein, which in turn recruits a splicing regulator. These results outline an adaptor system for reading of histone marks by the pre-mRNA splicing machinery. To obtain an estimate of how many PTB-dependent alternative splicing events are regulated by SET2/MRG15-mediated recruitment of PTB, we carried out a genomewide comparative analysis of alternative splicing in hMSC cells depleted of either SETD2, MRG15 or PTB using specific siRNAs, or mock-depleted using a control siRNA.
Project description:We provide data showing alternative splicing regulation by Muscleblind proteins in MEFs. MEFs lacking functional Muscleblind (DKO MEFs) were stably reconstituted with Muscleblind proteins from Homo sapiens, Ciona intestinalis, Drosophila melanogaster, Caenorhabditis elegans or Trichoplax adhaerens and splicing regulation was explored using RNA-seq analysis followed by MISO (Mixture of Isoforms). Alternative splicing was accessed using RNA-sequencing data from five DKO MEF lines reconstituted with different GFP-tagged Muscleblind homologs or GFP alone and compared to RNA-seq data from three WT MEF lines and three control DKO MEFs (no Muscleblind reconstitution). A total of 12 samples were used for high-throughput sequencing.
Project description:Background: Despite the prevalence and biological relevance of both signalling pathways and alternative pre-mRNA splicing, our knowledge of how intracellular signalling impacts on alternative splicing regulation remains fragmentary. We report a genome-wide analysis of changes in alternative splicing using splicing-sensitive microarrays, induced by activation of two distinct signalling pathways, insulin and wingless, in Drosophila cells in culture. Results: Alternative splicing changes induced by insulin affect more than 150 genes and more than 50 genes are regulated by wingless activation. About 40% of the genes showing changes in alternative splicing also show regulation of mRNA levels, suggesting distinct but also significantly overlapping programs of transcriptional and posttranscriptional regulation. Distinct functional sets of genes are regulated by each pathway and, remarkably, a significant overlap is observed between functional categories of genes regulated transcriptionally and at the level of alternative splicing. Functions related with carbohydrate metabolism and cellular signalling are enriched among genes regulated by insulin and wingless, respectively. Computational searches identify pathway-specific sequence motifs enriched near regulated 5â splice sites. Conclusion: Taken together, our data indicate that signalling cascades trigger pathway-specific and biologically coherent regulatory programs of alternative splicing regulation. They also reveal that alternative splicing can provide a novel molecular mechanism for cross-talk between different signalling pathways. To monitor transcriptional and alternative splicing changes induced by activation of the insulin and wingless pathways, a custom-designed microarray platform was employed featuring probes for all Drosophila genes for which different mRNA isoforms generated by alternative splicing have been described (see Blanchette M, Green RE, Brenner SE, Rio DC: Global analysis of positive and negative pre-mRNA splicing regulators in Drosophila. Genes Dev 2005, 19(11):1306-1314.). Three biological replicates of total RNA isolated after pathway activation or controls (untreated cells for insulin, control dsRNA for wingless) were purified, reverse transcribed into cDNA and labelled with Cy5 or Cy3 fluorochromes and the cDNA was hybridized to the microarray,
Project description:Alternative splicing of pre-mRNA is a prominent mechanism to generate protein diversity, yet its regulation is poorly understood. Here, we demonstrate a direct role for histone modifications in alternative splicing. We find distinctive histone modification signatures which correlate with splicing outcome in a set of human genes. Modulation of histone modifications causes splice site switching. The mechanism for histone-mediated splice site selection involves a histone mark which is read by a chromatin protein, which in turn recruits a splicing regulator. These results outline an adaptor system for reading of histone marks by the pre-mRNA splicing machinery.