Project description:Alternative splicing is prevalent in plants, but little is known about its regulation in the context of developmental and signaling pathways. We describe here a new factor that influences pre-mRNA splicing and is essential for embryonic development in Arabidopsis thaliana. This factor was retrieved in a genetic screen that identified mutants impaired in expression of an alternatively spliced GFP reporter gene. In addition to the known spliceosomal component PRP8, the screen retrieved a previously uncharacterized protein containing a Replication termination factor2 (Rtf2) domain defined by a C2HC2 zinc finger. The Rtf2 protein was discovered in fission yeast, where it stabilizes paused DNA replication forks by an unknown mechanism. When homozygous, a null mutation in Arabidopsis RTF2 (AtRTF2) is embryo-lethal, indicating that it encodes an essential protein. As revealed by quantitative RT-PCR, impaired expression of GFP in atrtf2 and prp8 mutants is attributable to inefficient splicing of the GFP pre-mRNA. A genome-wide analysis using RNA-seq demonstrated that 12% of total introns display a significant degree of retention in atrtf2 mutants. Intron-retaining transcripts are enriched from genes encoding proteins involved in signaling pathways and membrane transport. Affinity purification of AtRTF2 followed by mass spectrometry identified several known and predicted splicing proteins. In a yeast two-hybrid screen, AtRTF2 interacted with Exo70B1, a peripheral subunit of the exocyst, which is involved in vesicle trafficking. Considering these results and previous suggestions that Rtf2 constitutes an ubiquitin-related domain, we discuss possible roles of AtRTF2 in ubiquitin-based regulation of pre-mRNA splicing and membrane signaling to the spliceosome. Rtf2 is SDR1 (= AtRTF2) and was discovered in a genetic suppressor screen using the dms4 mutant. DMS4 was described in Kanno et al (2010) EMBO Rep. 11:65-71. Examination of whole-genome DNA methylation status in transgenic Arabidopsis plants
Project description:Alternative splicing is prevalent in plants, but little is known about its regulation in the context of developmental and signaling pathways. We describe here a new factor that influences pre-mRNA splicing and is essential for embryonic development in Arabidopsis thaliana. This factor was retrieved in a genetic screen that identified mutants impaired in expression of an alternatively spliced GFP reporter gene. In addition to the known spliceosomal component PRP8, the screen retrieved a previously uncharacterized protein containing a Replication termination factor2 (Rtf2) domain defined by a C2HC2 zinc finger. The Rtf2 protein was discovered in fission yeast, where it stabilizes paused DNA replication forks by an unknown mechanism. When homozygous, a null mutation in Arabidopsis RTF2 (AtRTF2) is embryo-lethal, indicating that it encodes an essential protein. As revealed by quantitative RT-PCR, impaired expression of GFP in atrtf2 and prp8 mutants is attributable to inefficient splicing of the GFP pre-mRNA. A genome-wide analysis using RNA-seq demonstrated that 12% of total introns display a significant degree of retention in atrtf2 mutants. Intron-retaining transcripts are enriched from genes encoding proteins involved in signaling pathways and membrane transport. Affinity purification of AtRTF2 followed by mass spectrometry identified several known and predicted splicing proteins. In a yeast two-hybrid screen, AtRTF2 interacted with Exo70B1, a peripheral subunit of the exocyst, which is involved in vesicle trafficking. Considering these results and previous suggestions that Rtf2 constitutes an ubiquitin-related domain, we discuss possible roles of AtRTF2 in ubiquitin-based regulation of pre-mRNA splicing and membrane signaling to the spliceosome. Rtf2 is SDR1 (= AtRTF2) and was discovered in a genetic suppressor screen using the dms4 mutant. DMS4 was described in Kanno et al (2010) EMBO Rep. 11:65-71.
Project description:This study investigated the role Rtf2 plays on the replication fork barrier (RFB) activity of RTS1 in S. pombe. We confirm Rtf2 is important for the full barrier activity of the RTS1-Rtf1 RFB. We show that Rtf2 does not enact its enhancing effect on RTS1 RFB activity via binding to Region A of RTS1, but instead we find it to be closely associated with several splicing factors. Analysis of cells deleted for rtf2 by cDNA-Seq reveal splicing defects specifically effecting intron retention, including for the Rtf1 transcript. We show that intron retention within rtf1 is responsible for the reduced barrier activity of RTS1 when rtf2 is deleted. This study reveals Rtf2 to be an important factor for maintaining efficient splicing within the cell.
Project description:This study investigated the role Rtf2 plays on the replication fork barrier (RFB) activity of RTS1 in S. pombe. We confirm Rtf2 is important for the full barrier activity of the RTS1-Rtf1 RFB. We show that Rtf2 does not enact its enhancing effect on RTS1 RFB activity via binding to Region A of RTS1, but instead we find it to be closely associated with several splicing factors. Analysis of cells deleted for rtf2 by cDNA-Seq reveal splicing defects specifically effecting intron retention, including for the Rtf1 transcript. We show that intron retention within rtf1 is responsible for the reduced barrier activity of RTS1 when rtf2 is deleted. This study reveals Rtf2 to be an important factor for maintaining efficient splicing within the cell.
Project description:J-proteins are structurally diverse, obligatory co-chaperones of Hsp70s, each with a highly conserved J-domain that plays a critical role in stimulation of Hsp70âs ATPase activity. The essential protein, Cwc23, is one of 13 J-proteins found in the cytosol and/or nucleus of Saccharomyces cerevisiae. We report that a partial loss-of-function CWC23 mutant has severe, global defects in pre-mRNA splicing. This mutation leads to accumulation of the excised, lariat form of the intron, as well as unspliced pre-mRNA, suggesting a role for Cwc23 in spliceosome disassembly. Such a role is further supported by the observation that this mutation results in reduced interaction between Cwc23 and Ntr1 (SPP382), a known component of the disassembly pathway. However, Cwc23 is a very atypical J-protein. Its J-domain, although functional, is dispensable for both cell viability and pre-mRNA splicing. Nevertheless, strong genetic interactions were uncovered between point mutations encoding alterations in Cwc23âs J-domain and either Ntr1 or Prp43, a DExD/H-box helicase essential for spliceosome disassembly. These genetic interactions suggest that Hsp70-based chaperone machinery does play a role in the disassembly process. Cwc23 provides a unique example of a J-protein; its partnership with Hsp70 plays an auxiliary, rather than a central, role in its essential cellular function. Splicing-sensitive microarrays were used to probe the defects seen when the C-terminal or N-terminal regions of Cwc23 were disrupted.
Project description:Influenza A viruses (IAVs) mRNA splicing represents an essential step in the viral life cycle. Here, we show that induction of SRSF5 by IAVs promotes viral replication by enhancing M mRNA splicing. To determine the motif in the M pre-mRNA targeted by SRSF5 RRM2 domain, the RNA eluted from co-precipitation of SRSF5–Flag from IAV-infected srsf5−/− HEK293 cells was subjected to deep sequencing analysis.
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:We identified non-POU domain-containing octamer-binding protein (NONO), a Drosophila behavior human splicing (DBHS) protein, among the most upregulated mRNA splicing factors in glioblastoma multiforme (GBM). NONO was associated with poor prognosis in GBM patients, and overexpression of NONO promoted GBM cell proliferation, invasion and tumorigenesis in a GBM orthotopic xenograft model. Through RNA sequencing based transcriptomic profiling, we found that knockdown of NONO resulted in global changes in alternative splicing-intron retention, and identified GPX1 and CCN1 as two pre-mRNAs targeted by NONO. NONO directly bound to the intron of GPX1 pre-mRNA through the RNA-recognition motifs 2 (RRM2) domain and required interaction with another DBHS protein family member, PSPC1. Knockdown of NONO interfered with redox homeostasis in cells, at least partially, through abnormal splicing of GPX1. Finally, Auranofin, a small-molecule inhibitor targeting NONO, inhibited GBM growth in an orthotopic xenograft model in mice. Taken together, our data revealed that NONO was a key regulator of mRNA splicing in GBM, and that targeting NONO represents a novel and effective therapeutic strategy for the treatment of GBM.
Project description:We identified non-POU domain-containing octamer-binding protein (NONO), a Drosophila behavior human splicing (DBHS) protein, among the most upregulated mRNA splicing factors in glioblastoma multiforme (GBM). NONO was associated with poor prognosis in GBM patients, and overexpression of NONO promoted GBM cell proliferation, invasion and tumorigenesis in a GBM orthotopic xenograft model. Through RNA sequencing based transcriptomic profiling, we found that knockdown of NONO resulted in global changes in alternative splicing-intron retention, and identified GPX1 and CCN1 as two pre-mRNAs targeted by NONO. NONO directly bound to the intron of GPX1 pre-mRNA through the RNA-recognition motifs 2 (RRM2) domain and required interaction with another DBHS protein family member, PSPC1. Knockdown of NONO interfered with redox homeostasis in cells, at least partially, through abnormal splicing of GPX1. Finally, Auranofin, a small-molecule inhibitor targeting NONO, inhibited GBM growth in an orthotopic xenograft model in mice. Taken together, our data revealed that NONO was a key regulator of mRNA splicing in GBM, and that targeting NONO represents a novel and effective therapeutic strategy for the treatment of GBM.