A novel minor spliceosome component required for splicing of AT-AC introns
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PROVIDER: PRJNA600275 | ENA |
REPOSITORIES: ENA
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Project description:U12-type introns were originally recognized based on their highly conserved non-consensus AT-AC termini1,2, which are spliced by a separate minor spliceosome3,4. Padgett and Krainer groups later showed that terminal dinucleotides do not differentiate U12-type from U2-type introns, as there are U12-type introns with GT-AG termini and U2-type introns with AT-AC termini5,6. Rather, U12-type introns are recognized by their divergent and highly conserved 5’ splice site (5’ss) and branch point sequences, which both differ from the consensus sequences found in U2-type introns. To date, no functional differences have been ascribed to AT-AC or GT-AG subtypes of U12-type introns, nor have RNAseq analyses of minor spliceosome diseases reported any subtype specificity. Here, we describe a novel protein component of the minor spliceosome, encoded by the CENATAC locus, that is required for accurate splicing of AT-AC but not GT-AG type minor introns. CENATAC was initially identified in a subset of Mosaic Variegated Aneuploidy (MVA) patients with mutations in CENATAC, which lead to chromosome congression defects during mitosis. Earlier large-scale proteomic analyses tentatively classified CENATAC as a spliceosome component and phylogenetic analyses showed co-segregation of CENATAC with minor spliceosome components. Targeted depletion of CENATAC in HeLa cells, followed by RNAseq revealed global retention of AT-AC minor subtype introns with more than 60% showing statistically significant (up to 90%) intron retention (IR). Additionally, U12-type introns with 5’-AT, but divergent 3’-terminal dinucleotides also showed significant IR. We also detected cryptic U2-type splice site activation near affected AT-AC introns. In contrast, about 10% of GT-AG subtype introns responded to CENATAC depletion. Co-IP experiments revealed that CENATAC is not a U11/U12 di-snRNP component as expected for a specificity factor, but rather associates with the U4atac/U6atac.U5 tri-snRNP via interaction with PRPF3/4, suggesting a role for minor tri-snRNP in initial 5’ss recognition. CENATAC also interacts with TXNL4B, a paralog of TXNL4A in the major tri-snRNP. Finally, several genes encoding chromosome congression factors harbor U12 AT-AC-type introns that were highly retained in CENATAC depleted cells, potentially explaining the aneuploidy phenotype observed in MVA patients.
2021-04-19 | GSE143392 | GEO
Project description:Aneuploidy is the leading cause of miscarriage and congenital birth defects, and a hallmark of cancer. Despite this strong association with human disease, the genetic causes of aneuploidy remain largely unknown. Through exome sequencing of patients with constitutional mosaic aneuploidy, we identified biallelic truncating mutations in CENATAC (CCDC84). We show that CENATAC is a novel component of the minor (U12-dependent) spliceosome that promotes splicing of a specific, rare minor intron subtype. This subtype is characterized by AT-AN splice sites and relatively high basal levels of intron retention. CENATAC depletion or expression of disease mutants resulted in excessive retention of AT-AN minor introns in ~100 genes enriched for nucleocytoplasmic transport and cell cycle regulators, and caused chromosome segregation errors. Our findings reveal selectivity in minor intron splicing and suggest a link between minor spliceosome defects and constitutional aneuploidy in humans.
2021-04-07 | PXD024682 | Pride
Project description:Mutations in minor spliceosome components are linked to diseases such as Roifman syndrome, Lowry-Wood syndrome, and early-onset cerebellar ataxia (EOCA). Here we report that besides increased minor intron retention, Roifman syndrome and EOCA can also be characterized by elevated alternative splicing (AS) around minor introns. Consistent with the idea that the assembly/activity of the minor spliceosome informs AS in minor intron-containing genes (MIGs), inhibition of all minor spliceosome snRNAs led to upregulated AS. Notably, alternatively spliced MIG isoforms were bound to polysomes in the U11-null dorsal telencephalon, which suggested that aberrant MIG protein expression could contribute to disease pathogenesis. In agreement, expression of an aberrant isoform of the MIG Dctn3 by in utero electroporation, affected radial glial cell divisions. Finally, we show that AS around minor introns is executed by the major spliceosome and is regulated by U11-59K of the minor spliceosome, which forms exon-bridging interactions with proteins of the major spliceosome. Overall, we extend the exon-definition model to MIGs and postulate that disruptions of exon-bridging interactions might contribute to disease severity and pathogenesis.
2021-05-01 | GSE151141 | GEO
Project description:Mutations in minor spliceosome components are linked to diseases such as Roifman syndrome, Lowry-Wood syndrome, and early-onset cerebellar ataxia (EOCA). Here we report that besides increased minor intron retention, Roifman syndrome and EOCA can also be characterized by elevated alternative splicing (AS) around minor introns. Consistent with the idea that the assembly/activity of the minor spliceosome informs AS in minor intron-containing genes (MIGs), inhibition of all minor spliceosome snRNAs led to upregulated AS. Notably, alternatively spliced MIG isoforms were bound to polysomes in the U11-null dorsal telencephalon, which suggested that aberrant MIG protein expression could contribute to disease pathogenesis. In agreement, expression of an aberrant isoform of the MIG Dctn3 by in utero electroporation, affected radial glial cell divisions. Finally, we show that AS around minor introns is executed by the major spliceosome and is regulated by U11-59K of the minor spliceosome, which forms exon-bridging interactions with proteins of the major spliceosome. Overall, we extend the exon-definition model to MIGs and postulate that disruptions of exon-bridging interactions might contribute to disease severity and pathogenesis.
2021-05-01 | GSE151140 | GEO
Project description:ZRSR2 is an essential splicing factor involved in 3’-splice site recognition as a component of both the major and minor spliceosomes that mediate splicing of U2- and U12-type introns, respectively. Transcriptome analysis of ZRSR2-mutated bone marrow samples and ZRSR2-knockdown cell lines has revealed its essential role in the minor spliceosome. We established a zrsr2-knockout zebrafish line, termed zrsr2hg129/hg129 (p.Trp167Argfs*9) using CRISPR/Cas9 technology. Global transcriptome analysis of 3 dpf zrsr2hg129/hg129 embryos revealed that loss of Zrsr2 leads to aberrant retention of minor introns in about one third of all minor intron-containing genes in zebrafish. Interestingly, these genes showed an enrichment for the RNA and protein processing pathways. Overall, our study has demonstrated that the role of Zrsr2 as a component of the minor spliceosome is conserved in zebrafish.
2022-09-28 | GSE193365 | GEO
Project description:We identify RBM41 as a novel unique protein component of the minor spliceosome. RBM41 has no previously recognized cellular function but has been identified as a paralog of the U11/U12-65K protein, a known unique component of the minor spliceosome that functions during the early steps of minor intron recognition as a component of the U11/U12 di-snRNP. We show that both proteins use their highly similar C-terminal RRMs to bind to 3'-terminal stem-loops in U12 and U6atac snRNAs with comparable affinity. Our BioID data indicate that the unique N-terminal domain of RBM41 is necessary for its association with complexes containing DHX8, an RNA helicase, which in the major spliceosome drives the release of mature mRNA from the spliceosome. Consistently, we show that RBM41 associates with excised U12-type intron lariats, is present in the U12 mono-snRNP, and is enriched in Cajal bodies, together suggesting that RBM41 functions in the post-splicing steps of the minor spliceosome assembly/disassembly cycle. This contrasts with the U11/U12-65K protein, which uses the N-terminal region to interact with U11 snRNP during the intron recognition step. Finally, we show that while RBM41 knockout cells are viable, they show alterations in the splicing of U12-type introns, particularly differential U12-type 3' splice site usage. Together, our results highlight the role 3’-terminal stem-loop of U12 snRNA as a dynamic binding platform for the paralogous U11/U12-65K and RBM41 proteins, which function at distinct stages of minor spliceosome assembly/disassembly cycle.
2024-02-04 | GSE246283 | GEO
Project description:Most eukaryotes harbor two distinct pre-mRNA splicing machineries: the major spliceosome, which removes >99% of introns, and the minor spliceosome, which removes rare, evolutionarily conserved introns. Although hypothesized to serve important regulatory functions, physiologic roles for the minor spliceosome are not well understood. For example, the minor spliceosome component ZRSR2 is subject to recurrent, leukemia-associated mutations, yet functional connections between minor introns, hematopoiesis, and cancers are unclear. Here, we identify that impaired minor intron excision via ZRSR2 loss enhances hematopoietic stem cell self-renewal. CRISPR screens mimicking nonsense-mediated decay of minor intron-containing mRNAs converged on LZTR1, a regulator of Ras-related GTPases. LZTR1 minor intron retention was also discovered in the RASopathy Noonan syndrome, due to intronic mutations disrupting splicing, and diverse solid tumors. These data uncover minor intron recognition as a regulator of hematopoiesis, noncoding mutations within minor introns as cancer drivers, and links between ZRSR2 mutations, LZTR1 regulation, and leukemias.
2021-02-09 | GSE149455 | GEO
Project description:Most metazoans contain two distinct pre-mRNA splicing machineries: the major spliceosome, which removes >99% of introns, and the minor spliceosome, which recognizes <1% of introns. Despite their rarity, minor introns are exquisitely conserved amongst species, suggesting important regulatory functions. However, physiologic roles for the minor spliceosome and the relevance of recurrent, leukemia-associated mutations affecting minor spliceosome components are not well understood. Here, we identify that mutational loss of the minor spliceosomal factor ZRSR2 enhances hematopoietic stem cell self-renewal via impaired minor intron splicing that converges on LZTR1, a regulator of Ras-related GTPases. LZTR1 minor intron retention is additionally observed in Noonan syndrome and diverse cancers. These data uncover minor intron recognition as a regulator of hematopoiesis and mechanistic links between ZRSR2 mutations, LZTR1, and leukemia.
2020-11-26 | GSE162136 | GEO
Project description:In this work, we identify RBM41 as a novel unique protein component of the minor spliceosome. RBM41 has no previously recognized cellular function but has been identified as a paralog of the U11/U12-65K protein, a known unique component of the minor spliceosome that functions during the early steps of minor intron recognition as a component of the U11/U12 di-snRNP. We show that both proteins use their highly similar C-terminal RRMs to bind to 3'-terminal stem-loops in U12 and U6atac snRNAs with comparable affinity. Our BioID data indicate that the unique N-terminal domain of RBM41 is necessary for its association with complexes containing DHX8, an RNA helicase, which in the major spliceosome drives the release of mature mRNA from the spliceosome.
| MSV000092983 | MassIVE
Project description:Somatic mutations in the spliceosome gene ZRSR2 (located on the X chromosome) are associated with myelodysplastic syndrome (MDS). ZRSR2 is involved in the recognition of 3' splice site during the early stages of spliceosome assembly; however, its precise role in RNA splicing has remained unclear. Here, we characterize ZRSR2 as an essential component of the minor spliceosome (U12-dependent) assembly. shRNA mediated knockdown of ZRSR2 leads to impaired splicing of the U12-type introns, and RNA-Sequencing of MDS bone marrow reveals that loss of ZRSR2 activity causes increased mis-splicing. These splicing defects involve retention of the U12-type introns while splicing of the U2-type introns remain mostly unaffected. ZRSR2 deficient cells also exhibit reduced proliferation potential and distinct alterations in myeloid and erythroid differentiation in vitro. These data identify a specific role for ZRSR2 in RNA splicing and highlight dysregulated splicing of U12-type introns as a characteristic feature of ZRSR2 mutations in MDS. RNA sequencing was performed on 16 bone marrow samples (MDS and normal) and six samples of control or ZRSR2 shRNA transduced TF-1 cells and data was analysed for aberrant splicing caused by ZRSR2 mutations/deficiency.
2015-01-15 | E-GEOD-63816 | biostudies-arrayexpress