Project description:Alternative splicing is a key process underlying the evolution of increased proteomic and functional complexity and is especially prevalent in the mammalian nervous system. However, the factors and mechanisms governing nervous system-specific alternative splicing are not well understood. Through a genome-wide computational and expression profiling strategy, we have identified a tissue- and vertebrate-restricted Ser/Arg (SR)-repeat splicing factor, the neural-specific SR-related protein of 100 kDa (nSR100). We show that nSR100 regulates an extensive network of brain-specific alternative exons enriched in genes that function in neural cell differentiation. nSR100 acts by increasing the levels of the neural/brain-enriched polypyrimidine tract binding protein and by interacting with its target transcripts. Disruption of nSR100 prevents neural cell differentiation in cell culture and in the developing zebrafish. Our results thus reveal a critical neural-specific alternative splicing regulator, the evolution of which has contributed to increased complexity in the vertebrate nervous system. A microarray platform to profile alternative splicing levels for 8714 cassette-type alternative exons across a diverse spectrum of mouse tissues.
Project description:How species with similar repertoires of protein coding genes differ so dramatically at the phenotypic level is poorly understood. From comparing the transcriptomes of multiple organs from vertebrate species spanning ~350 million years of evolution, we observe significant differences in alternative splicing complexity between the main vertebrate lineages, with the highest complexity in the primate lineage. Moreover, within as little as six million years, the splicing profiles of physiologically-equivalent organs have diverged to the extent that they are more strongly related to the identity of a species than they are to organ type. Most vertebrate species-specific splicing patterns are governed by the highly variable use of a largely conserved cis-regulatory code. However, a smaller number of pronounced species-dependent splicing changes are predicted to remodel interactions involving factors acting at multiple steps in gene regulation. These events are expected to further contribute to the dramatic diversification of alternative splicing as well as to other gene regulatory changes that contribute to phenotypic differences among vertebrate species. mRNA profiles of several organs (brain, liver, kidney, heart, skeletal muscle) in multiple vertebrate species (mouse, chicken, lizard, frog, pufferfish) generated by deep sequencing using Illumina HiSeq
Project description:<p>RNA sequencing was performed on human DRGs and relative gene abundances were calculated.</p> <p>Various analyses were performed:</p> <p> <ol> <li>Human DRG gene expression profiles were contrasted with a panel of gene expression profiles of relevant tissues in human and mouse ( integrating, among other sources, datasets from ENCODE and GTex ) in order to identify.</li> <ol type="a"> <li>DRG-enriched gene expression, co-expression modules of DRG-expressed genes, and key transcriptional regulators in humans.</li> <li>Contrasting the human and mouse DRG transcriptomes to identify DRG-enriched gene expression patterns that were conserved between human and mouse, identifying putative cell types of expression of these genes, and potential known drugs that might target the corresponding gene products.</li> <li>Characterization of non-coding RNA profile of human and mouse DRGs.</li> <li>Characterization of DRG-enriched alternative splicing and alternative transcription start site usage based transcript variants in humans and mouse, and the overlap between these two species.</li> <li>Contrasting of human DRG and GTex human tibial nerve samples to identify putative axonally transported mRNAs in sensory neurons.</li> </ol> <li>Human DRG transcriptomes from donors suffering from neuropathic and/or chronic pain were contrasted with controls to identify.</li> <ol type="a"> <li>Differentially expressed genes, pathways and regulators path play a potential role in neuronal plasticity, electrophysiological activity, immune signaling and response.</li> <li>Predictive models (Random Forests) were built to jointly predict the sex and pain state of samples based on information contained solely in autosomal gene expression profile.</li> <li>Gene co-expression modules were identified and gene set enrichment analysis performed.to identify sample - pathway associations, and to broadly characterize plasticity in human DRG cell types.</li> </ol> </ol> </p>
Project description:We characterized by RNA-seq the transcriptional profiles of a large and heterogeneous collection of mouse tissues, augmenting the mouse transcriptome with thousands of novel transcript candidates. Comparison with transcriptome profiles obtained in human cell lines reveals substantial conservation of transcriptional programs, and uncovers a distinct class of genes with levels of expression across cell types and species, that have been constrained early in vertebrate evolution. This core set of genes capture a substantial and constant fraction of the transcriptional output of mammalian cells, and participates in basic functional and structural housekeeping processes common to all cell types. Perturbation of these constrained genes is associated with significant phenotypes including embryonic lethality and cancer. Evolutionary constraint in gene expression levels is not reflected in the conservation of the genomic sequences, but it is associated with strong and conserved epigenetic marking, as well as to a characteristic post-transcriptional regulatory program in which sub-cellular localization and alternative splicing play comparatively large roles.
Project description:Most mammalian genes produce multiple distinct mRNAs through alternative splicing, but the extent of splicing conservation is not clear. To assess tissue-specific transcriptome variation across mammals, we sequenced cDNA from 9 tissues from 4 mammals and one bird in biological triplicate, at unprecedented depth. We find that while tissue-specific gene expression programs are largely conserved, alternative splicing is well conserved in only a subset of tissues and is frequently lineage-specific. Thousands of novel, lineage-specific and conserved alternative exons were identified; widely conserved alternative exons had signatures of binding by MBNL, PTB, RBFOX, STAR and TIA family splicing factors, implicating them as ancestral mammalian splicing regulators. Our data also indicates that alternative splicing is often used to alter protein phosphorylatability, delimiting the scope of kinase signaling. Tissue transcriptomes from 9 tissues from 5 species, 3 individuals per species, were sequenced and compared (two samples for mouse_heart). <br> Curation note: E-GEOD-41637 (9 tissues, 5 organisms) has been split into five artefactual ArrayExpress experiments, one experiment per species for inclusion in Expression Atlas. Each artefactual experiment omits the processed data files (which are still available via the original E-GEOD-41637 records). Chicken: E-MTAB-2797; Cow: E-MTAB-2798; Rhesus monkey: E-MTAB-2799; Rat: E-MTAB-2800; Mouse: E-MTAB-2801
Project description:We characterized by RNA-seq the transcriptional profiles of a large and heterogeneous collection of mouse tissues, augmenting the mouse transcriptome with thousands of novel transcript candidates. Comparison with transcriptome profiles obtained in human cell lines reveals substantial conservation of transcriptional programs, and uncovers a distinct class of genes with levels of expression across cell types and species, that have been constrained early in vertebrate evolution. This core set of genes capture a substantial and constant fraction of the transcriptional output of mammalian cells, and participates in basic functional and structural housekeeping processes common to all cell types. Perturbation of these constrained genes is associated with significant phenotypes including embryonic lethality and cancer. Evolutionary constraint in gene expression levels is not reflected in the conservation of the genomic sequences, but it is associated with strong and conserved epigenetic marking, as well as to a characteristic post-transcriptional regulatory program in which sub-cellular localization and alternative splicing play comparatively large roles. Comparison of human and mouse transcriptome profiles has uncovered a distinct class of genes (6600- one third of all expressed genes in both human and mouse) whose variation in expression levels have been constrained irrespective of cell types and species that they are express in. Such constraint appears to have been developed early in vertebrate evolution since it seen in multiple other species. This constraint is not associated with the conservation of the genomic sequences found in each species. Finally, this core set of genes helps in interpreting how non-human organisms like the mouse can better be used as models for human disease and why perturbation of these constrained genes is associated with significant phenotypes including embryonic lethality and cancer.
Project description:How species with similar repertoires of protein coding genes differ so dramatically at the phenotypic level is poorly understood. From comparing the transcriptomes of multiple organs from vertebrate species spanning ~350 million years of evolution, we observe significant differences in alternative splicing complexity between the main vertebrate lineages, with the highest complexity in the primate lineage. Moreover, within as little as six million years, the splicing profiles of physiologically-equivalent organs have diverged to the extent that they are more strongly related to the identity of a species than they are to organ type. Most vertebrate species-specific splicing patterns are governed by the highly variable use of a largely conserved cis-regulatory code. However, a smaller number of pronounced species-dependent splicing changes are predicted to remodel interactions involving factors acting at multiple steps in gene regulation. These events are expected to further contribute to the dramatic diversification of alternative splicing as well as to other gene regulatory changes that contribute to phenotypic differences among vertebrate species.
Project description:Alternative splicing is a key process underlying the evolution of increased proteomic and functional complexity and is especially prevalent in the mammalian nervous system. However, the factors and mechanisms governing nervous system-specific alternative splicing are not well understood. Through a genome-wide computational and expression profiling strategy, we have identified a tissue- and vertebrate-restricted Ser/Arg (SR)-repeat splicing factor, the neural-specific SR-related protein of 100 kDa (nSR100). We show that nSR100 regulates an extensive network of brain-specific alternative exons enriched in genes that function in neural cell differentiation. nSR100 acts by increasing the levels of the neural/brain-enriched polypyrimidine tract binding protein and by interacting with its target transcripts. Disruption of nSR100 prevents neural cell differentiation in cell culture and in the developing zebrafish. Our results thus reveal a critical neural-specific alternative splicing regulator, the evolution of which has contributed to increased complexity in the vertebrate nervous system.