Single-cell mRNA isoform diversity in the mouse brain
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE76026 | GEO | 2017/01/01
SECONDARY ACCESSION(S): PRJNA306027
REPOSITORIES: GEO
Similar Datasets
Project description:Alternative splicing of mRNA diversifies the function of human proteins, with tissue- and cell-specific protein isoforms being the most difficult to validate. While transcriptomic experiments enable the detection of many alternatively spliced transcripts, it is not known if these transcripts have protein-coding potential. We recently published the PG Nexus pipeline, which facilitates high confidence validation of exons and exon-exon junctions of spliced transcripts by integrating transcriptomics and proteomics data. Using the PG Nexus, we analyzed undifferentiated human mesenchymal stem cells and compared the number of protein isoforms validated using different protein sequence database, including public online databases and RNA-seq derived databases. With significant overlaps with other databases, we identified 8,011 exons and 3,824 splice junctions with the Ensembl database. Both exonic and junction peptides were important for protein isoform validation. The Ensembl database consistently outperformed the other data sources, but predicted open reading frames from RNA-seq derived transcripts were comparable, with only 6 less splice junctions validated. Using proteotypic and isoform-specific peptides, we validated 462 protein isoforms. This number increases to 1,083 if multiple proteotypic peptides per protein are included. Multiplexing proteotypic peptides in SRM assays or similar experiments will increase the confidence and coverage of protein isoform validation experiments.
2015-05-20 | PXD001449 | Pride
Project description:Alternative splicing is an essential mechanism for diversifying proteins, with different mature RNA isoforms producing different proteins with potentially distinct functions. Two major challenges in characterizing the cellular function of isoforms are the lack of both experimental methods to specifically and efficiently modulate isoform expression and computational tools for complex experimental design. To address these gaps, we developed and methodically tested a strategy which pairs the RNA-targeting CRISPR/Cas13d system with guide RNAs (gRNAs) that overlap exon-exon junctions in the mature RNA. We perform a high-throughput essentiality screen, numerous qPCR assays, and PacBio long read sequencing to affirm that our strategy works to specifically target the unique junctions of isoforms to robustly knockdown their RNA. In parallel, we provide computational tools for experimental design and screen analysis. Considering all possible splice junctions in current GENCODE annotations and our predictions of gRNA efficacy, we estimate that this strategy can target 94% of all human isoforms, including 29,238 protein-coding and 9,638 lncRNA isoforms that are specifically targetable with a gRNA spanning a unique splice junction.
2023-09-13 | GSE242106 | GEO
Project description:Alternative splicing is an essential mechanism for diversifying proteins, with different mature RNA isoforms producing different proteins with potentially distinct functions. Two major challenges in characterizing the cellular function of isoforms are the lack of both experimental methods to specifically and efficiently modulate isoform expression and computational tools for complex experimental design. To address these gaps, we developed and methodically tested a strategy which pairs the RNA-targeting CRISPR/Cas13d system with guide RNAs (gRNAs) that overlap exon-exon junctions in the mature RNA. We perform a high-throughput essentiality screen, numerous qPCR assays, and PacBio long read sequencing to affirm that our strategy works to specifically target the unique junctions of isoforms to robustly knockdown their RNA. In parallel, we provide computational tools for experimental design and screen analysis. Considering all possible splice junctions in current GENCODE annotations and our predictions of gRNA efficacy, we estimate that this strategy can target 94% of all human isoforms, including 29,238 protein-coding and 9,638 lncRNA isoforms that are specifically targetable with a gRNA spanning a unique splice junction.
2023-09-13 | GSE242105 | GEO
Project description:Alternative splicing is an essential mechanism for diversifying proteins, with different mature RNA isoforms producing different proteins with potentially distinct functions. Two major challenges in characterizing the cellular function of isoforms are the lack of both experimental methods to specifically and efficiently modulate isoform expression and computational tools for complex experimental design. To address these gaps, we developed and methodically tested a strategy which pairs the RNA-targeting CRISPR/Cas13d system with guide RNAs (gRNAs) that overlap exon-exon junctions in the mature RNA. We perform a high-throughput essentiality screen, numerous qPCR assays, and PacBio long read sequencing to affirm that our strategy works to specifically target the unique junctions of isoforms to robustly knockdown their RNA. In parallel, we provide computational tools for experimental design and screen analysis. Considering all possible splice junctions in current GENCODE annotations and our predictions of gRNA efficacy, we estimate that this strategy can target 94% of all human isoforms, including 29,238 protein-coding and 9,638 lncRNA isoforms that are specifically targetable with a gRNA spanning a unique splice junction.
2023-09-13 | GSE242104 | GEO
Project description:Through alternative processing of pre-mRNAs, individual mammalian genes often produce multiple mRNA and protein isoforms that may have related, distinct or even opposing functions. Here we report an in-depth analysis of 15 diverse human tissue and cell line transcriptomes based on deep sequencing of cDNA fragments, yielding a digital inventory of gene and mRNA isoform expression. Analysis of mappings of sequence reads to exon-exon junctions indicated that ~94% of human genes undergo alternative splicing (AS), ~86% with a minor isoform frequency of 15% or more. Differences in isoform-specific read densities indicated that a majority of AS and alternative cleavage and polyadenylation (APA) events exhibit variation between tissues. Variations in alternative mRNA isoform expression between 6 individuals were also detected in cerebellar cortex, with ~2- to 3-fold less isoform variation observed between individuals than between tissues. Extreme or 'switch-like' regulation of splicing between tissues was associated with increased sequence conservation and with generation of full-length open reading frames. Patterns of AS and APA were strongly correlated across tissues, suggesting coordinated regulation, and sequence conservation of known regulatory motifs in both regulated introns and 3' UTRs suggested common involvement of the same factors in regulation of tissue-specific splicing and polyadenylation. Exam mRNA expression in 15 human tissues and cell lines
2008-09-30 | E-GEOD-12946 | biostudies-arrayexpress
Project description:The rise in throughput and quality of long-read sequencing should allow unambiguous identification of full-length transcript isoforms. However, its application to single-cell RNA-seq has been limited by throughput and expense. Here we develop and characterize long-read Split-seq (LR-Split-seq), which uses combinatorial barcoding to sequence single cells with long reads. Applied to the C2C12 myogenic system, LR-split-seq associates isoforms to cell types with relative economy and design flexibility. We find widespread evidence of changing isoform expression during differentiation including alternative transcription start sites (TSS) and/or alternative internal exon usage. LR-Split-seq provides an affordable method for identifying cluster-specific isoforms in single cells.
2021-03-12 | GSE168776 | GEO
Project description:Through alternative processing of pre-mRNAs, individual mammalian genes often produce multiple mRNA and protein isoforms that may have related, distinct or even opposing functions. Here we report an in-depth analysis of 15 diverse human tissue and cell line transcriptomes based on deep sequencing of cDNA fragments, yielding a digital inventory of gene and mRNA isoform expression. Analysis of mappings of sequence reads to exon-exon junctions indicated that ~94% of human genes undergo alternative splicing (AS), ~86% with a minor isoform frequency of 15% or more. Differences in isoform-specific read densities indicated that a majority of AS and alternative cleavage and polyadenylation (APA) events exhibit variation between tissues. Variations in alternative mRNA isoform expression between 6 individuals were also detected in cerebellar cortex, with ~2- to 3-fold less isoform variation observed between individuals than between tissues. Extreme or 'switch-like' regulation of splicing between tissues was associated with increased sequence conservation and with generation of full-length open reading frames. Patterns of AS and APA were strongly correlated across tissues, suggesting coordinated regulation, and sequence conservation of known regulatory motifs in both regulated introns and 3' UTRs suggested common involvement of the same factors in regulation of tissue-specific splicing and polyadenylation.
2008-10-01 | GSE12946 | GEO
Project description:Deregulated gene expression is a hallmark of cancer, however most studies to date have analyzed short-read RNA-sequencing data with inherent limitations. Here, we combine PacBio long-read isoform sequencing (Iso-Seq) and Illumina paired-end short read RNA sequencing to comprehensively survey the transcriptome of gastric cancer (GC), a leading cause of global cancer mortality. We performed full-length transcriptome analysis across 10 GC cell lines covering four major GC molecular subtypes (chromosomal unstable, Epstein-Barr positive, genome stable and microsatellite unstable). We identify 60,239 non-redundant full-length transcripts, of which >66% are novel compared to current transcriptome databases. Novel isoforms are more likely to be cell-line and subtype specific, expressed at lower levels with larger number of exons, with longer isoform/coding sequence lengths. Most novel isoforms utilize an alternate first exon, and compared to other alternative splicing categories are expressed at higher levels and exhibit higher variability. Collectively, we observe alternate promoter usage in 25% of detected genes, with the majority (84.2%) of known/novel promoter pairs exhibiting potential changes in their coding sequences. Mapping these alternate promoters to TCGA GC samples, we identify several cancer-associated isoforms, including novel variants of oncogenes. Tumor-specific transcript isoforms tend to alter protein coding sequences to a larger extent than other isoforms. Analysis of outcome data suggests that novel isoforms may impart additional prognostic information. Our results provide a rich resource of full-length transcriptome data for deeper studies of GC and other gastrointestinal malignancies.
2021-02-02 | PXD023373 | Pride
Project description:Zebrafish embryos are transcriptional silent until activation of the zygotic genome during the 10th cell cycle. Onset of transcription is followed by cellular and morphological changes involving cell speciation and gastrulation. Previous genome-wide surveys of transcriptional changes only assessed gene expression levels; however, recent studies have shown the necessity to map isoform-specific transcriptional changes. Here we perform isoform discovery and quantification on transcriptome sequences from before and after zebrafish zygotic genome activation (ZGA). We identify novel isoforms and isoform switches during ZGA for genes related to cell adhesion, pluripotency and DNA methylation. Isoform switching events include alternative splicing and changes in transcriptional start sites and in 3’ untranslated regions. New isoforms are identified even for well-characterized genes such as pou5f1, sall4 and dnmt1. Genes involved in cell-cell interactions such as f11r and magi1 display isoform switches with alterations of coding sequences. We also detect over 1000 transcripts that acquire a longer 3’ terminal exon when transcribed zygotically relative to the maternal transcript counterparts. ChIP-seq data mapped onto skipped exon events reveals a correlation between histone H3K36trimethylation peaks and the skipped exons, suggesting epigenetic marks being part of alternative splicing regulation. The novel isoforms and isoform switches reported here include regulators of the transcriptional, cellular and morphological changes taking place around ZGA. Our data display an array of isoform-related functional changes and represent a valuable resource complementary to existing early embryo transcriptomes. Examination H3K36me3 in zebrafish whole embryos at the Post-MBT stage
2012-11-01 | E-GEOD-40629 | biostudies-arrayexpress
Project description:Alternative splicing increases the diversity of transcriptomes and proteomes in metazoans. The extent to which alternative splicing is active and functional in unicellular organisms is less understood. Here we exploit a single-molecule long-read sequencing technique and develop a computational tool, SpliceHunter, to characterize the transcriptome in the meiosis of fission yeast. We reveal 17017 alternative splicing events in 19741 novel isoforms at different stages of meiosis, including antisense and read-through transcripts. Intron retention is the major type of alternative splicing, followed by “alternate intron in exon”. 887 novel transcription units are detected; 60 of the predicted proteins show homology in other species and form theoretical stable structures. We compare the dynamics of novel isoforms based on the number of supporting full-length reads with those of annotated isoforms and explore the translational capacity and quality of novel isoforms. The evaluation of these factors indicates that the majority of novel isoforms are unlikely to be both condition-specific and translatable but the possibility of functional novel isoforms is not excluded. Together, this study highlights the diversity and dynamics at the isoform level in the sexual development of fission yeast.
2016-11-10 | GSE79802 | GEO