Chromosomal instability by mutations in the novel minor spliceosome component CENATAC.
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ABSTRACT:
SUBMITTER: de Wolf B
PROVIDER: S-EPMC8280824 | biostudies-literature |
REPOSITORIES: biostudies-literature
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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: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:Small nuclear RNAs (snRNAs) are essential factors in messenger RNA splicing. By means of homozygosity mapping and deep sequencing, we show that a gene encoding U4atac snRNA, a component of the minor U12-dependent spliceosome, is mutated in individuals with microcephalic osteodysplastic primordial dwarfism type I (MOPD I), a severe developmental disorder characterized by extreme intrauterine growth retardation and multiple organ abnormalities. Functional assays showed that mutations (30G>A, 51G>A, 55G>A, and 111G>A) associated with MOPD I cause defective U12-dependent splicing. Endogenous U12-dependent but not U2-dependent introns were found to be poorly spliced in MOPD I patient fibroblast cells. The introduction of wild-type U4atac snRNA into MOPD I cells enhanced U12-dependent splicing. These results illustrate the critical role of minor intron splicing in human development.
| S-EPMC3380448 | biostudies-literature
Project description:The role of many splicing factors in pre-mRNA splicing and the involvement of these factors in the processing of specific transcripts have often been defined through the analysis of loss-of-function mutants in vivo. Here we show that inactivating the nonsense-mediated mRNA decay (NMD) results in an enhancement of splicing phenotypes associated with several S. cerevisiae splicing factor mutations. Tiling microarrays showed that inactivation of the NMD factor Upf1p in the prp17Delta and prp18Delta mutant strains results in a larger spectrum of splicing defects than what is observed in the single mutants, including new transcripts previously shown unaffected by Prp17p or Prp18p inactivation. Inactivation of Upf1p in the second step/recycling factor prp22-1 mutant and in the nam8Delta and mud1Delta U1 snRNP component mutants also increase unspliced precursor accumulation of several specific transcripts. In addition, deletion of UPF1 partially suppresses the growth defects associated with the prp17Delta or prp22-1 mutations, demonstrating a positive genetic interaction between NMD and splicing factor mutants. These results show that RNA surveillance by NMD can mask some of the effects of splicing factor mutations, and that the roles of splicing factors cannot be fully understood in vivo unless RNA degradation systems that degrade unspliced precursors are also inactivated.
| S-EPMC2779665 | biostudies-literature
Project description:In the human genome, about 750 genes contain one intron excised by the minor spliceosome. This spliceosome comprises its own set of snRNAs, among which U4atac. Its noncoding gene, RNU4ATAC, has been found mutated in Taybi-Linder (TALS/microcephalic osteodysplastic primordial dwarfism type 1), Roifman (RFMN), and Lowry-Wood (LWS) syndromes. These rare developmental disorders, whose physiopathological mechanisms remain unsolved, associate ante- and post-natal growth retardation, microcephaly, skeletal dysplasia, intellectual disability, retinal dystrophy, and immunodeficiency. Here, we report bi-allelic RNU4ATAC mutations in five patients presenting with traits suggestive of the Joubert syndrome (JBTS), a well-characterized ciliopathy. These patients also present with traits typical of TALS/RFMN/LWS, thus widening the clinical spectrum of RNU4ATAC-associated disorders and indicating ciliary dysfunction as a mechanism downstream of minor splicing defects. Intriguingly, all five patients carry the n.16G>A mutation, in the Stem II domain, either at the homozygous or compound heterozygous state. A gene ontology term enrichment analysis on minor intron-containing genes reveals that the cilium assembly process is over-represented, with no less than 86 cilium-related genes containing at least one minor intron, among which there are 23 ciliopathy-related genes. The link between RNU4ATAC mutations and ciliopathy traits is supported by alterations of primary cilium function in TALS and JBTS-like patient fibroblasts, as well as by u4atac zebrafish model, which exhibits ciliopathy-related phenotypes and ciliary defects. These phenotypes could be rescued by WT but not by pathogenic variants-carrying human U4atac. Altogether, our data indicate that alteration of cilium biogenesis is part of the physiopathological mechanisms of TALS/RFMN/LWS, secondarily to defects of minor intron splicing.
| S-EPMC9992838 | biostudies-literature
Project description:The role of many splicing factors in pre-mRNA splicing and the involvement of these factors in the processing of specific transcripts have often been defined through the analysis of loss of function mutants in vivo. Here we show that inactivating the nonsense mediated mRNA decay (NMD) results in an enhancement of splicing phenotypes associated with several splicing factors mutations. Tiling microarrays showed that inactivation of the NMD factor Upf1p in the prp17Î and prp18Î mutant strains reveals a larger spectrum of splicing defects than what is observed in the single mutants, including new transcripts previously shown unaffected by Prp17p or Prp18p inactivation. In addition, inactivation of Upf1 in the prp22-1 mutant enhances the unspliced precursor accumulation phenotype of several specific transcripts and partially suppresses growth defects associated with the prp17Î or prp22-1 mutations. These results support the idea that RNA surveillance by NMD mutes some of the effects of splicing factors mutations and show that the roles of splicing factors and their transcripts specificity cannot be fully understood in vivo unless RNA degradation systems that degrade unspliced precursors are also inactivated. Three samples from the Prp17delta, Prp18delta, Prp17deltaUpf1delta and Prp18Upf1delta mutants were grown indepedently and analyzed by tiling arrays to understand the role of the NMD component Upf1 in minimizing the accumulation of unspliced RNAs generated by the Prp17delta and Prp18delta splicing mutations.
2010-05-16 | E-GEOD-18288 | biostudies-arrayexpress
Project description:A novel minor spliceosome component required for splicing of AT-AC introns
| PRJNA600275 | ENA
Project description:The role of many splicing factors in pre-mRNA splicing and the involvement of these factors in the processing of specific transcripts have often been defined through the analysis of loss of function mutants in vivo. Here we show that inactivating the nonsense mediated mRNA decay (NMD) results in an enhancement of splicing phenotypes associated with several splicing factors mutations. Tiling microarrays showed that inactivation of the NMD factor Upf1p in the prp17Δ and prp18Δ mutant strains reveals a larger spectrum of splicing defects than what is observed in the single mutants, including new transcripts previously shown unaffected by Prp17p or Prp18p inactivation. In addition, inactivation of Upf1 in the prp22-1 mutant enhances the unspliced precursor accumulation phenotype of several specific transcripts and partially suppresses growth defects associated with the prp17Δ or prp22-1 mutations. These results support the idea that RNA surveillance by NMD mutes some of the effects of splicing factors mutations and show that the roles of splicing factors and their transcripts specificity cannot be fully understood in vivo unless RNA degradation systems that degrade unspliced precursors are also inactivated.
2009-12-31 | GSE18288 | GEO
Project description:Pre-mRNA splicing factors play a fundamental role in regulating transcript diversity both temporally and spatially. Genetic defects in several spliceosome components have been linked to a set of non-overlapping spliceosomopathy phenotypes in humans, among which skeletal developmental defects and non-syndromic retinitis pigmentosa (RP) are frequent findings. Here we report that defects in spliceosome-associated protein CWC27 are associated with a spectrum of disease phenotypes ranging from isolated RP to severe syndromic forms. By whole-exome sequencing, recessive protein-truncating mutations in CWC27 were found in seven unrelated families that show a range of clinical phenotypes, including retinal degeneration, brachydactyly, craniofacial abnormalities, short stature, and neurological defects. Remarkably, variable expressivity of the human phenotype can be recapitulated in Cwc27 mutant mouse models, with significant embryonic lethality and severe phenotypes in the complete knockout mice while mice with a partial loss-of-function allele mimic the isolated retinal degeneration phenotype. Our study describes a retinal dystrophy-related phenotype spectrum as well as its genetic etiology and highlights the complexity of the spliceosomal gene network.
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Project description:Most solid cancers are characterized by chromosomal instability (CIN)-an elevated rate of large-scale chromosomal aberrations and ploidy changes. Chromosomal instability may arise through mutations in a range of genomic integrity loci and is commonly associated with fast disease progression, poor prognosis, and multidrug resistance. However, the evolutionary forces promoting CIN-inducing alleles (hereafter, CIN mutators) during carcinogenesis remain poorly understood. Here, we develop a stochastic, individual-based model of indirect selection experienced by CIN mutators via genomic associations with fitness-affecting mutations. Because mutations associated with CIN affect large swaths of the genome and have the potential to simultaneously comprise many individual loci, we show that indirect selection on CIN mutators is critically influenced by genome organization. In particular, we find strong support for a key role played by the spatial clustering of loci with either beneficial or deleterious mutational effects. Genomic clustering of selected loci allows CIN mutators to generate favorable chromosomal changes that facilitate their rapid expansion within a neoplasm and, in turn, accelerate carcinogenesis. We then examine the distribution of oncogenic and tumor-suppressing loci in the human genome and find both to be potentially more clustered along the chromosome than expected, leading us to speculate that human genome may be susceptible to CIN hitchhiking. More quantitative data on fitness effects of individual mutations will be necessary, though, to assess the true levels of clustering in the human genome and the effectiveness of indirect selection for CIN. Finally, we use our model to examine how therapeutic strategies that increase the deleterious burden of genetically unstable cells by raising either the rate of CIN or the cost of deleterious mutations affect CIN evolution. We find that both can inhibit CIN hitchhiking and delay carcinogenesis in some circumstances, yet, in line with earlier work, we find the latter to be considerably more effective.
| S-EPMC6346662 | biostudies-literature