Project description:In search for nuclear partners of initiator-tRNA, previously shown to be involved in a quality control of splice site selection, we identified nucleolin (NCL) as specifically and directly bound to it in the nucleus and not in the cytoplasm (using affinity purification of UV crosslinked nuclear initiator-tRNA followed by mass spectrometry). To further explore the role of NCL in splice site selection, we knocked down NCL. We report the activation of 399 latent splice sites upon NCL knockdown, as revealed by RNA deep sequencing of siRNA treated NCL compared to control siRNA. Our study identifies NCL as the first protein component of this quality control mechanism of splice site selection. Our study thus establishes an experimental strategy and computational pipeline that could be used to identify other components of this quality control mechanism.
Project description:CryoEM modeling of the human pre-B complex suggests an interaction between SNU66(H734) and SNRP27(M141) at the base of the ACAGAGA box of U6. We had previously shown in C. elegans that SNRP-27(M141T) mutants alter 5'ss usage. Here we generate new alleles by CRISPR in snu-66 at the corresponding H765 location in C. elegans (H765G and H765L) and demonstrate that they have similar effects as SNRP-27(M141T) mutants on 5'ss selection globally.
Project description:Whole-exome sequencing studies have identified common mutations affecting genes encoding components of the RNA splicing machinery in hematological malignancies. Here, we sought to determine how mutations affecting the 3' splice site recognition factor U2AF1 altered its normal role in RNA splicing. We find that U2AF1 mutations influence the similarity of splicing programs in leukemias, but do not give rise to widespread splicing failure. U2AF1 mutations cause differential splicing of hundreds of genes, affecting biological pathways implicated in myeloid disease such as DNA methylation (DNMT3B), X chromosome inactivation (H2AFY), the DNA damage response (ATR, FANCA), and apoptosis (CASP8). We show that U2AF1 mutations alter the preferred 3' splice site motif in vivo, in cell culture, and in vitro. Mutations affecting the first and second zinc fingers give rise to different alterations in splice site preference and largely distinct downstream splicing programs. These allele-specific effects are consistent with a computationally predicted model of U2AF1 in complex with RNA. Our findings suggest that U2AF1 mutations contribute to pathogenesis by causing quantitative changes in splicing that affect diverse cellular pathways, and give insight into the normal function of U2AF1’s zinc finger domains. mRNA profiles of K562 cells expressing U2AF1 WT, mutants and knockdown of U2AF1 generated by deep sequencing.
Project description:Whole-exome sequencing studies have identified common mutations affecting genes encoding components of the RNA splicing machinery in hematological malignancies. Here, we sought to determine how mutations affecting the 3' splice site recognition factor U2AF1 altered its normal role in RNA splicing. We find that U2AF1 mutations influence the similarity of splicing programs in leukemias, but do not give rise to widespread splicing failure. U2AF1 mutations cause differential splicing of hundreds of genes, affecting biological pathways implicated in myeloid disease such as DNA methylation (DNMT3B), X chromosome inactivation (H2AFY), the DNA damage response (ATR, FANCA), and apoptosis (CASP8). We show that U2AF1 mutations alter the preferred 3' splice site motif in vivo, in cell culture, and in vitro. Mutations affecting the first and second zinc fingers give rise to different alterations in splice site preference and largely distinct downstream splicing programs. These allele-specific effects are consistent with a computationally predicted model of U2AF1 in complex with RNA. Our findings suggest that U2AF1 mutations contribute to pathogenesis by causing quantitative changes in splicing that affect diverse cellular pathways, and give insight into the normal function of U2AF1’s zinc finger domains.
Project description:OThe N6-methyladenosine (m6A) RNA modification is widely used to alter the fate of mRNAs. Here we demonstrate that the C. elegans writer METT-10 (orthologue of mouse METTL16) deposits an m6A mark on the 3′ splice site (AG) of the SAM synthetase pre-mRNA which inhibits its proper splicing and protein production. The mechanism is triggered by a rich diet, and acts as an m6A-mediated switch to stop SAM production and regulate its homeostasis. Although the mammalian SAM synthetase pre-mRNA is not regulated via this mechanism, we show that splicing inhibition by 3′ splice site m6A is conserved in mammals. The modification functions by physically preventing the essential splicing factor U2AF35 from recognizing the 3′ splice site. We propose that use of splice site m6A is an ancient mechanism for splicing regulation.
Project description:We are interested in the contribution mutations in the Shelterin complex protein POT1 may have to the development of melanoma. We have identified a patient who carries a splice site mutation in POT1 and as part of our analysis of this gene we aim to sequence the transcriptome of this patient to see how this mutation influences splicing. RNA has been obtained from lymphocytes collected from the patient.
Project description:Splicing is a central process in metazoans and greatly expands their proteome by alternative splicing of pre-mRNA transcripts. An essential regulatory step during early spliceosome assembly is the recognition of cis-regulatory RNA motifs in pre-mRNAs. Here, we identified the RNA binding protein FUBP1 as a novel core splicing factor with a ubiquitous footprint on pre-mRNAs. FUBP1 binds to a previously unknown cis-regulatory motif upstream of the branch point of human introns. We show that FUBP1 binds and stabilises known 3' splice site components such as the essential splicing factor U2AF2. FUBP1 mutant cell lines and patient data indicate that FUBP1 is particularly relevant for efficient splicing of exons flanked by long introns. In addition to its role at the 3’ splice site, FUBP1 shows multiple interactions with U1 snRNP- associated proteins. This demonstrates an important role for FUBP1 in splice site bridging in the context of long introns.
Project description:Splicing is a central process in metazoans and greatly expands their proteome by alternative splicing of pre-mRNA transcripts. An essential regulatory step during early spliceosome assembly is the recognition of cis-regulatory RNA motifs in pre-mRNAs. Here, we identified the RNA binding protein FUBP1 as a novel core splicing factor with a ubiquitous footprint on pre-mRNAs. FUBP1 binds to a previously unknown cis-regulatory motif upstream of the branch point of human introns. We show that FUBP1 binds and stabilises known 3' splice site components such as the essential splicing factor U2AF2. FUBP1 mutant cell lines and patient data indicate that FUBP1 is particularly relevant for efficient splicing of exons flanked by long introns. In addition to its role at the 3’ splice site, FUBP1 shows multiple interactions with U1 snRNP- associated proteins. This demonstrates an important role for FUBP1 in splice site bridging in the context of long introns.
Project description:Splicing is a central process in metazoans and greatly expands their proteome by alternative splicing of pre-mRNA transcripts. An essential regulatory step during early spliceosome assembly is the recognition of cis-regulatory RNA motifs in pre-mRNAs. Here, we identified the RNA binding protein FUBP1 as a novel core splicing factor with a ubiquitous footprint on pre-mRNAs. FUBP1 binds to a previously unknown cis-regulatory motif upstream of the branch point of human introns. We show that FUBP1 binds and stabilises known 3' splice site components such as the essential splicing factor U2AF2. FUBP1 mutant cell lines and patient data indicate that FUBP1 is particularly relevant for efficient splicing of exons flanked by long introns. In addition to its role at the 3’ splice site, FUBP1 shows multiple interactions with U1 snRNP- associated proteins. This demonstrates an important role for FUBP1 in splice site bridging in the context of long introns.