Project description:Analysis of splicing defects in Schizosaccharomyces pombe upon chemical genetic inhibition of splicing kinases dsk1, lkh1, and prp4, as well as alanine-mutation of phosphorylated residues in the splicing factors bpb1, prp2, rsd1, srp1, srp2, usp101, usp103, sum3, prp22, cdc5, and cwf22. This study shows the splicing kinase dsk1 modulates splicing efficiency of introns with non-consensus splice sites, likely through phosphorylation of bpb1. Modulation of splicing efficiency of transcripts through kinase signaling pathways may afford the necessary flexibility to tune the gene expression profile in response to environmental and developmental cues.
Project description:Analysis of splicing defects in Schizosaccharomyces pombe upon chemical genetic inhibition of splicing kinases dsk1, lkh1, and prp4, as well as alanine-mutation of phosphorylated residues in the splicing factors bpb1, prp2, rsd1, srp1, srp2, usp101, usp103, sum3, prp22, cdc5, and cwf22. This study shows the splicing kinase dsk1 modulates splicing efficiency of introns with non-consensus splice sites, likely through phosphorylation of bpb1. Modulation of splicing efficiency of transcripts through kinase signaling pathways may afford the necessary flexibility to tune the gene expression profile in response to environmental and developmental cues. Experiments were conducted as direct two-color designs with 2-3 biological replicates per genotype pairing. Raw microarray data was normalized with loess normalization using the R package limma. Log2-fold changes (perturbation over reference) are reported. Each splicing event on the custom-designed splicing microarray was monitored with an exon probe reading out mRNA changes, an intron probe for unspliced pre-mRNA, and a splice junction probe spanning the junction between two spliced exons. For the analysis of the splicing efficiency for a given intron, a score was calculated as exon*intron/junction.
Project description:Nuclear 3’ to 5’ nuclease RNA exosome plays a key role in quality control and processing of multiple protein-coding and non-coding transcripts made by RNA polymerase II. A mechanistic understanding of exosome function remains a challenge given the large number of RNA species and intervening RNA processing factors. Here we analysed changes in the poly(A)+ RNA proteins interactome provoked by mutations in three distinct subunits of the nuclear RNA exosome. Our data demonstrate a functional connection between Rrp6 and Mtl1 in controlling processing and levels of multiple protein-coding and non-coding transcripts. Furthermore, we show that exosome mutants accumulate components of U1 and U2 snRNPs and show depletion of NTC components from RNA suggesting that the stage prior to the activation of the spliceosome represents a critical quality control step. We have also identified potential new RNA binding factors involved in exosome regulation, including a zinc-finger protein called Mub1 that controls levels of selected transcripts encoding for proteins implicated in stress response. Collectively, our data have provided a global view of RNA metabolism alterations in exosome deficient cells and revealed RNA binding proteins that may act as novel exosome cofactors.
Project description:The spliceosome is a dynamic macromolecular machine that catalyzes the removal of introns from pre-mRNA to make mature message. Schizosaccharomyces pombe Cwf10 (homolog Saccharomyces cerevisiae Snu114 and of Human U5-116K), an integral member of the U5 snRNP, is a GTPase that shares sequence homology with the eukaryotic translation elongation factor EF2. Cwf10 is required for pre-mRNA splicing; however, its mechanism(s) of action is still not understood. Cwf10/Snu114 family members contain a conserved N-terminal extension (NTE) that lacks homology with EF2 and has been predicted to be an intrinsically unfolded domain. Using S. pombe as a model system, we show that the NTE is not essential, but cells lacking this domain are defective in pre-mRNA splicing at all temperatures. Genetic interactions between cwf10-M-NM-^TNTE and other pre-mRNA splicing mutants are consistent with a role for the NTE in spliceosome activation. Characterization of Cwf10-NTE by various biophysical techniques shows the NTE contains both regions of structure and disorder in solution. The first twenty-three highly-conserved amino acids of the NTE are essential for its role in splicing, but are not sufficient to restore pre-mRNA splicing to wild-type levels in cwf10-M-bM-^HM-^FNTE cells. When the NTE is overexpressed in the cwf10-M-NM-^TNTE background, it can complement the truncated Cwf10 protein in trans, and it also immunoprecipitates a complex similar in composition to the late-stage U5.U2/U6 spliceosome. These data show that the structurally flexible NTE is capable of making specific contacts within the spliceosome that may facilitate Cwf10M-bM-^@M-^Ys overall role facilitating spliceosome rearrangements. Interrogation of the S. pombe transcriptome using poly-A enriched RNA sequencing (Illumina HiSeq 2500) in wild type and cwf10-M-NM-^TNTE cultures. A total of 4 samples were analysed: two biological repeats of wild-type strain and two biological repeats of cwf10-M-NM-^TNTE
Project description:The spliceosome is a dynamic macromolecular machine that catalyzes the removal of introns from pre-mRNA to make mature message. Schizosaccharomyces pombe Cwf10 (homolog Saccharomyces cerevisiae Snu114 and of Human U5-116K), an integral member of the U5 snRNP, is a GTPase that shares sequence homology with the eukaryotic translation elongation factor EF2. Cwf10 is required for pre-mRNA splicing; however, its mechanism(s) of action is still not understood. Cwf10/Snu114 family members contain a conserved N-terminal extension (NTE) that lacks homology with EF2 and has been predicted to be an intrinsically unfolded domain. Using S. pombe as a model system, we show that the NTE is not essential, but cells lacking this domain are defective in pre-mRNA splicing at all temperatures. Genetic interactions between cwf10-ΔNTE and other pre-mRNA splicing mutants are consistent with a role for the NTE in spliceosome activation. Characterization of Cwf10-NTE by various biophysical techniques shows the NTE contains both regions of structure and disorder in solution. The first twenty-three highly-conserved amino acids of the NTE are essential for its role in splicing, but are not sufficient to restore pre-mRNA splicing to wild-type levels in cwf10-∆NTE cells. When the NTE is overexpressed in the cwf10-ΔNTE background, it can complement the truncated Cwf10 protein in trans, and it also immunoprecipitates a complex similar in composition to the late-stage U5.U2/U6 spliceosome. These data show that the structurally flexible NTE is capable of making specific contacts within the spliceosome that may facilitate Cwf10’s overall role facilitating spliceosome rearrangements.
Project description:Pre-mRNA splicing is a key process in the regulation of gene expression as reflected by its disruption in various diseases. Previously, we have demonstrated that the spliceosome-associated factor Nrl1 of the fission yeast S. pombe, except of its role in suppression of accumulation of genome-threatening R-loops, also affects splicing and expression of several genes and non-coding RNAs. To uncover the molecular mechanisms regulating the function of Nrl1, we performed here the systematic analysis of its protein-protein interactions at the domain level. We found that N-terminal region of Nrl1 secures the interaction of Nrl1 with ATP-dependent RNA helicase Mtl1 but is incapable of docking of Nrl1 into the spliceosome. Contrary, the C-terminal region of Nrl1 was found to be critical for the interactions of Nrl1 with other splicing factors and the stable binding of Nrl1 into the spliceosome. Importantly, we showed that splicing function of Nrl1 depends on its phosphorylation. Additionally, we identified two amino acid residues of Nrl1, namely S122 and S131, which are directly phosphorylated by Cka1 protein kinase. Together, our results indicate the novel features involved in the regulation of spliceosome-associated factor Nrl1, defined by its domain-dependent interactions and by the CKII-dependent phosphorylation.