Abstract: Alternative splicing (AS) plays a major role in the generation of proteomic diversity and in gene regulation. However, the role of the basal splicing machinery in regulating AS remains poorly understood. Here we show that the core snRNP protein SmB/B’ self-regulates its expression by promoting the inclusion of a highly-conserved alternative exon in its own pre-mRNA that targets the spliced transcript for nonsense-mediated mRNA decay (NMD). Depletion of SmB/B’ in human cells results in reduced levels of snRNPs and in a striking reduction in the inclusion levels of hundreds of alternative exons, with comparatively few effects on constitutive exon splicing levels. The affected alternative exons are enriched in genes encoding RNA processing and other RNA binding factors, and a subset of these exons also regulate gene expression by activating NMD. Our results thus demonstrate a role for the core spliceosomal machinery in controlling an exon network that appears to modulate the levels of many RNA processing factors. Overall design: HeLa cells were transfected with a control non-targeting siRNA pool (siNT), or with siRNA pools designed to knockdown SmB/B'' or SRSF1 (also known as SF2/ASF/SFRS1). Sequence reads were aligned to exon-exon junction sequences in a database of EST/cDNA-mined cassette-type alternative splicing events. Processed data files (.bed and .txt) provided as supplementary files on the Series record. Processed data file build information: hg18.
Regulation of alternative splicing by the core spliceosomal machinery.
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View SamplesAlternative splicing of pre-mRNA is a prominent mechanism to generate protein diversity, yet its regulation is poorly understood. Here, we demonstrate a direct role for histone modifications in alternative splicing. We find distinctive histone modification signatures which correlate with splicing outcome in a set of human genes. Modulation of histone modifications causes splice site switching. The mechanism for histone-mediated splice site selection involves a histone mark which is read by a chromatin protein, which in turn recruits a splicing regulator. These results outline an adaptor system for reading of histone marks by the pre-mRNA splicing machinery. Overall design: To obtain an estimate of how many PTB-dependent alternative splicing events are regulated by SET2/MRG15-mediated recruitment of PTB, we carried out a genomewide comparative analysis of alternative splicing in hMSC cells depleted of either SETD2, MRG15 or PTB using specific siRNAs, or mock-depleted using a control siRNA.
Regulation of alternative splicing by histone modifications.
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View SamplesAutism spectrum disorder (ASD) is a common, highly heritable neuro-developmental condition characterized by marked genetic heterogeneity. Thus, a fundamental question is whether autism represents an etiologically heterogeneous disorder in which the myriad genetic or environmental risk factors perturb common underlying molecular pathways in the brain. Here, we demonstrate consistent differences in transcriptome organization between autistic and normal brain by gene co-expression network analysis. Remarkably, regional patterns of gene expression that typically distinguish frontal and temporal cortex are significantly attenuated in the ASD brain, suggesting abnormalities in cortical patterning. We further identify discrete modules of co-expressed genes associated with autism: a neuronal module enriched for known autism susceptibility genes, including the neuronal specific splicing factor A2BP1/FOX1, and a module enriched for immune genes and glial markers. Using high-throughput RNA-sequencing we demonstrate dysregulated splicing of A2BP1-dependent alternative exons in ASD brain. Moreover, using a published autism GWAS dataset, we show that the neuronal module is enriched for genetically associated variants, providing independent support for the causal involvement of these genes in autism. In contrast, the immune-glial module showed no enrichment for autism GWAS signals, indicating a non-genetic etiology for this process. Collectively, our results provide strong evidence for convergent molecular abnormalities in ASD, and implicate transcriptional and splicing dysregulation as underlying mechanisms of neuronal dysfunction in this disorder.
Transcriptomic analysis of autistic brain reveals convergent molecular pathology.
Disease
View SamplesThe rate of RNA Polymerase II (RNAPII) elongation has an important role in the control of Alternative splicing (AS); however, the in vivo consequences of an altered elongation rate are unknown. Here, we generated mouse embryonic stem cells (ESCs) knocked-in for a slow elongating form of RNAPII. We show that a reduced transcriptional elongation rate results in early embryonic lethality in mice and impairs the differentiation of ESCs into the neural lineage. This is accompanied by changes in splicing and in gene expression in ESCs and along the pathway of neuronal differentiation. In particular, we found a crucial role for RNAPII elongation rate in transcription and splicing of long neuronal genes involved in synapse signaling. The impact of the kinetic coupling of RNAPII elongation rate with AS is more predominant in ESC-differentiated neurons than in pluripotent cells. Our results demonstrate the requirement for an appropriate transcriptional elongation rate to ensure proper gene expression and to regulate AS during development. Overall design: 4sURDB-Seq mouse wt and homozygous Polr2a[R749H] mutant embryonic stem cells in triplicates.
A slow transcription rate causes embryonic lethality and perturbs kinetic coupling of neuronal genes.
Treatment, Subject
View SamplesAutism spectrum disorder (ASD) is a common, highly heritable neurodevelopmental condition characterized by marked genetic heterogeneity. Thus, a fundamental question is whether autism represents an aetiologically heterogeneous disorder in which the myriad genetic or environmental risk factors perturb common underlying molecular pathways in the brain. Here, we demonstrate consistent differences in transcriptome organization between autistic and normal brain by gene co-expression network analysis. Remarkably, regional patterns of gene expression that typically distinguish frontal and temporal cortex are significantly attenuated in the ASD brain, suggesting abnormalities in cortical patterning. We further identify discrete modules of co-expressed genes associated with autism: a neuronal module enriched for known autism susceptibility genes, including the neuronal specific splicing factor A2BP1 (also known as FOX1), and a module enriched for immune genes and glial markers. Using high-throughput RNA sequencing we demonstrate dysregulated splicing of A2BP1-dependent alternative exons in the ASD brain. Moreover, using a published autism genome-wide association study (GWAS) data set, we show that the neuronal module is enriched for genetically associated variants, providing independent support for the causal involvement of these genes in autism. In contrast, the immune-glial module showed no enrichment for autism GWAS signals, indicating a non-genetic aetiology for this process. Collectively, our results provide strong evidence for convergent molecular abnormalities in ASD, and implicate transcriptional and splicing dysregulation as underlying mechanisms of neuronal dysfunction in this disorder. Overall design: To identify potential A2BP1-dependent differential splicing events in ASD brain, we performed high-throughput RNA sequencing (RNA-Seq) on three autism samples with significant downregulation of A2BP1 (average fold change by quantitative RT-PCR = 5.9) and three control samples with average A2BP1 levels. The list of potential A2BP1-depending differential splicing events in ASD is given in the Supplementary file linked at the foot of this record.
Transcriptomic analysis of autistic brain reveals convergent molecular pathology.
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View SamplesThe formation and execution of a productive immune response requires, among many things, the maturation of competent T cells and a robust change in cellular activity upon antigen challenge. Such changes in cellular function require regulated alterations of protein expression. Much work has previously gone into defining the transcriptional changes that regulate protein expression during T cell development and antigen stimulation. Here we describe a parallel pathway of gene regulation that occurs during T cell stimulation, namely alternative splicing. Specifically, we use RNA-Seq to identify 178 exons in 168 genes that exhibit robust changes in inclusion in response to a stimulation of a human T cell line. Interestingly, these signal-responsive genes are enriched for functions related to immune response including, cell trafficking, inflammatory and immune response, immunologic disease and several cell signaling pathways. The vast majority of these genes also exhibit different isoform expression in naive and activated primary T cells. Comparison of the responsiveness of splicing to various stimuli in the cultured and primary T cells reveal important insight into the diversity of signaling pathways that control splicing. Using this data we are able to classify signal-responsive exons into at least three distinct networks. Importantly, we find that each regulatory network is characterized by distinct sequence hallmarks, further suggesting independent regulatory mechanisms. Overall design: We utilize high-throughput RNA sequencing (RNA-Seq) to investigate global changes in alternative splicing in a cultured T cell line and in primary human T cells. We identify 178 genes that are predicted to exhibit robust signal-induced changes in isoform expression in cultured T cells.
Alternative splicing networks regulated by signaling in human T cells.
Specimen part, Subject
View SamplesPurpose: The goal of this study was to assess gene expression changes in neurons overexpressing SOX5 using human primary neuronal culture system. Methods: 6 samples each from control GFP and SOX5 overexpressing neurons were used to isolate total RNA using miRNeasy kit, Qiagen. We performed rRNA-depleted 69bp paired end stranded RNA-seq on neurons overexpressing either GFP or SOX5 tagged with GFP. Overexpression of SOX5 in neurons validated that a significant proportion of Attenuated cortical patterning (ACP) genes are regulated by SOX5, and that predicted SOX5 targets exhibit a net downregulation, consist with its repressive function. This supports the prediction that attenuated patterning of SOX5 between cortical regions contributes to direct alterations in SOX5 targets and likely to indirect alterations in SOX5 non-targets in the ACP set. delpleted 69 bp stranded RNA-seq in Overall design: SOX5 was overexpressed in primary human neuronal cultures using a lentiviral system. Briefly full-length human SOX5 gene was cloned in pLVU/GFP vector (gift from Lars Ittner [Addgene plasmid #24177]) using the gateway recombination technique. Lentivirus was produced in HEK293T cells using a second generation packaging vector system (psPAX2, a gift from Didier Trono [Addgene plasmid #12260] and pCMV-VSV-G, a gift from Bob Weinberg [Addgene plasmid #8454]) as described by Stewart et al., 200331. Primary human neurons were infected at plating at a multiplicity of infection (MOI) of 10 with either the SOX5 overexpressing construct or a control pLVU-GFP backbone vector. 14 days after infection, RNA from the samples were isolated using miRNeasy micro kit (Qiagen, Carlsbad) and 50bp paired-end libraries were prepared using SMARter Stranded Total RNA sample prep kit (Clontech) with rRNA depletion. Libraries were then multiplexed and sequenced with HiSeq 2500 instrument (Illumina).
Genome-wide changes in lncRNA, splicing, and regional gene expression patterns in autism.
Specimen part, Treatment, Subject
View SamplesAlternative splicing (AS) is a key process underlying the expansion of proteomic diversity and the regulation of gene expression. However, the contribution of AS to the control of embryonic stem cell (ESC) pluripotency is not well understood. Here, we identify an evolutionarily conserved ESC-specific AS event that changes the DNA binding preference of the forkhead family transcription factor FOXP1. We show that the ESC-specific isoform of FOXP1 stimulates the expression of transcription factor genes required for pluripotency including OCT4, NANOG, NR5A2 and GDF3, while concomitantly repressing genes required for ESC differentiation. Remarkably, this isoform also promotes the maintenance of ESC pluripotency and the efficient reprogramming of somatic cells to induced pluripotent stem cells. These results thus reveal that an AS switch plays a pivotal role in the regulation of pluripotency and functions by controlling critical ESC-specific transcriptional programs. Overall design: Exons 18 and 18b form a mutually exclusive splicing event. The FOXP1 (non-ES) isoform contains only exon 18 and not 18b, while the FOXP1-ES isoform contains only exon 18b and not 18. To investigate whether FOXP1 and FOXP1-ES control different sets of genes, we performed knockdowns using custom siRNA pools targeting FOXP1 exons 18 or 18b in undifferentiated H9 cells, followed by RNA-Seq profiling.
An alternative splicing switch regulates embryonic stem cell pluripotency and reprogramming.
Specimen part, Subject
View SamplesEstablishment and application of RNAseq based transcriptome analayis on an archivaed bladder cancer cohort. Overall design: Total RNA profilling 61 archived bladder cancer samples and comparison of 4 pairs of fresh frozen and FFPE bladder cancer samples.
Next-generation RNA sequencing of archival formalin-fixed paraffin-embedded urothelial bladder cancer.
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View SamplesEmbryonic stem cells are maintained in a self-renewing and pluripotent state by multiple regulatory pathways. Pluripotent-specific transcriptional networks are sequentially reactivated as somatic cells reprogram to achieve pluripotency. How epigenetic regulators modulate this process and contribute to somatic cell reprogramming is not clear. Here we perform a functional RNAi screen to identify the earliest epigenetic regulators required for reprogramming. We identify components of the SAGA histone acetyltransferase complex, in particular Gcn5, as critical regulators of reprogramming initiation. Furthermore, we show in mouse pluripotent stem cells that Gcn5 strongly associates with Myc and that upon initiation of somatic reprogramming, Gcn5 and Myc form a positive feed forward loop that activates a distinct alternative splicing network and the early acquisition of pluripotency-associated splicing events. These studies expose a Myc-SAGA pathway that drives expression of an essential alternative splicing regulatory network during somatic cell reprogramming. Overall design: Examination of expression level changes at D0 and D2 MEFs
Myc and SAGA rewire an alternative splicing network during early somatic cell reprogramming.
No sample metadata fields
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