Project description:The exon junction complex (EJC) deposited upstream of mRNA exon junctions shapes structure, composition and fate of spliced mRNA ribonucleoprotein particles (mRNPs). To achieve this, the EJC core nucleates assembly of a dynamic shell of peripheral proteins that function in diverse post-transcriptional processes. In this study we show that EJC exists in two mutually exclusive compositions characterized by peripheral proteins RNPS1 and CASC3. We identified transcriptome-wide binding sites of the two alternate EJCs via RNA:protein immunoprecipitation in tandem followed by deep sequencing (RIPiT-Seq). We show that RNPS1-EJC, which is an SR-rich mega-dalton sized RNP, is the major EJC form in the nucleus. After mRNP export to the cytoplasm and before translation, the EJC undergoes a remarkable compositional and structural remodeling into an SR- and RNPS1-devoid monomeric complex that contains CASC3. The CASC3-EJC is enriched on cytoplasmic RNAs and is the main EJC form that encounters ribosome and undergoes disassembly during translation.
Project description:The nuclear cap-binding complex (CBC) stimulates processing reactions of capped RNAs, including their splicing, 3'-end formation, degradation, and transport. CBC effects are particular for individual RNA families, but how such selectivity is achieved remains elusive. Here, we analyze three main CBC partners known to impact different RNA species. ARS2 stimulates 3'-end formation/transcription termination of several transcript types, ZC3H18 stimulates degradation of a diverse set of RNAs, and PHAX functions in pre-small nuclear RNA/small nucleolar RNA (pre-snRNA/snoRNA) transport. Surprisingly, these proteins all bind capped RNAs without strong preferences for given transcripts, and their steady-state binding correlates poorly with their function. Despite this, PHAX and ZC3H18 compete for CBC binding and we demonstrate that this competitive binding is functionally relevant. We further show that CBC-containing complexes are short lived in vivo, and we therefore suggest that RNA fate involves the transient formation of mutually exclusive CBC complexes, which may only be consequential at particular checkpoints during RNA biogenesis.
Project description:This series represents 52 tissues hybridized across 5 different chip patterns. Probes were placed at every exon-exon junction in each transcript. Keywords = junction alternate splicing oligonucleotide Keywords: parallel sample. This dataset is part of the TransQST collection.
Project description:71 liver RNA samples from three mouse strains - DBA/2J, C57BL/6J and C3H/HeJ - were profiled using a custom-designed microarray monitoring exon and exon-junction expression of 1,020 genes representing 9,406 exons. Gene expression was calculated via two different methods, using the 3'-most exon probe ("3' gene expression profiling") and using all probes associated with the gene ("whole-transcript gene expression profiling"), while exon expression was determined using exon probes and flanking junction probes that spanned across the neighboring exons("exon expression profiling"). Widespread strain and sex influences were detected using a two-way Analysis of Variance (ANOVA) regardless of the profiling method used. However, over 90% of the genes identified in 3' gene expression profiling or whole transcript profiling were identified in exon profiling, along with 75% and 38% more genes, respectively, showing evidence of differential isoform expression. Overall, 55% and 32% of genes, respectively, exhibited strain- and sex-bias differential gene or exon expression. Keywords: Grouped
Project description:The exon junction complex (EJC) is composed of three core proteins Rbm8a, Magoh and Eif4a3 and is thought to play a role in several post-transcriptional processes. In this study we focus on understanding the role of EJC in zebrafish development. We identified transcriptome-wide binding sites of EJC in zebrafish via RNA:protein immunoprecipitation followed by deep sequencing (RIP-Seq). We find that, as in human cells, zebrafish EJC is deposited about 24 nts upstream of exon-exon junctions. We also identify transcripts regulated by Rbm8a and Magoh in zebrafish embryos using whole embryo RNA-seq from rbm8a mutant, magoh mutant and wild-type sibling embryos. This study shows that nonsense mediated mRNA decay is dysregulated in zebrafish EJC mutants.
Project description:71 liver RNA samples from three mouse strains - DBA/2J, C57BL/6J and C3H/HeJ - were profiled using a custom-designed microarray monitoring exon and exon-junction expression of 1,020 genes representing 9,406 exons. Gene expression was calculated via two different methods, using the 3'-most exon probe ("3' gene expression profiling") and using all probes associated with the gene ("whole-transcript gene expression profiling"), while exon expression was determined using exon probes and flanking junction probes that spanned across the neighboring exons("exon expression profiling"). Widespread strain and sex influences were detected using a two-way Analysis of Variance (ANOVA) regardless of the profiling method used. However, over 90% of the genes identified in 3' gene expression profiling or whole transcript profiling were identified in exon profiling, along with 75% and 38% more genes, respectively, showing evidence of differential isoform expression. Overall, 55% and 32% of genes, respectively, exhibited strain- and sex-bias differential gene or exon expression. Keywords: Grouped Hybridization material was generated through a random-priming amplification of poly[A]+ purified RNA using primers with a random sequence at the 3' end and a fixed motif at the 5' end that was optimized to generate strand-specific cDNA copies of full-length mRNA transcripts [32]. Since the region used for exon and junction probe selection is constrained to a smaller region, more probes contain sequence with suboptimal characteristics (e.g. high GC content or higher homology to other genes). The hybridization of cDNA, rather than cRNA as commonly done, partially mitigates this issue due to higher specificity and lower background levels [24]. Hybridization conditions were as previously described [33]. All 71 samples were hybridized in a two-channel experiment, where one channel was a common reference, generated by pooling all 71 samples in equal mass. Array hybridizations were done in duplicate with fluor reversal to systematically correct for Cy3/Cy5 dye bias. Array images were processed as described to obtain background noise, single channel intensity and associated measurement error estimates [34]. Expression changes between samples and pool were quantified as mean log10(expression ratio), and associated error.
Project description:Tumors acquire somatic DNA copy number aberrations, leading to activation of oncogenes and inactivation of tumor suppressors. Many studies have focused on the analysis of single copy number aberrations and associated driver genes, but few studies have performed combinatorial analyses. We propose a genome-wide scoring framework to find mutually exclusive gains and losses. Mutually exclusive copy number aberrations can identify genes whose oncogenic function is redundant, either by functioning in the same pathway or in a parallel pathway. As one gene is aberrated the selective pressure for its partner is alleviated which leads to a mutually exclusive perturbation pattern. In a dataset of mouse models for invasive lobular carcinoma we found three mutually exclusive DNA amplifications, containing several well-known oncogenes: the Met proto-oncogene on chromosome 6, the cluster of Birc2, Birc3 and Yap1 genes on chromosome 9, and Nras on chromosome 3. Furthermore, gene expression or protein expression of these genes correlates very well with copy number data indicating that they are the target of the amplification. Although homologous amplifications in human tumors are rare, the mutual exclusivity of MET, BIRC/YAP1 and NRAS is maintained in a variety of cancer types. This suggests a novel function for YAP1 in the mitogen-activated signaling pathway by association with MET and NRAS, known players in this pathway. This function is independent to the propensity of YAP1 to cause Epithelial-to-Mesenchymal transition. aCGH data of 67 mouse mammary tumors from K14-Cre and WAP-Cre driven P53-F/F;Cdh1-F/F animals - tumor DNA hybridized against same-animal splenic DNA
Project description:N6–methyladenosine (m6A) is the most abundant mRNA modification and plays crucial roles in diverse physiological processes. Utilizing a Massively Parallel Assay for m6A (MPm6A), we discover that m6A specificity is globally regulated by “suppressors” that prevent m6A deposition in unmethylated transcriptome regions. We identify Exon Junction Complexes (EJCs) as m6A suppressors that protect exon junction-proximal RNA within coding sequences from methylation and regulate mRNA stability through m6A suppression. EJC suppression of m6A underlies multiple global characteristics of mRNA m6A specificity, with the local range of EJC protection sufficient to suppress m6A deposition in average-length internal exons, but not in long internal and terminal exons. EJC-suppressed methylation sites co-localize with EJC-suppressed splice sites, suggesting that exon architecture broadly determines local mRNA accessibility to regulatory complexes.