Project description:Alternative splicing (AS) generates isoform diversity critical for cellular identity and homeostasis, yet characterization of this diversity in single cells remains limited. We developed Expedition, a computational framework to categorize and visualize the heterogeneity of AS from single-cell transcriptomes. Expedition consists of (i) outrigger, a de novo splice graph transversal algorithm to detect AS from single cell RNA-seq; (ii) anchor, a Bayesian approach to assign splicing modalities and (iii) bonvoyage, using non-negative matrix factorization to visualize modality changes. By applying Expedition to single iPSCs undergoing neuron differentiation, we discover that 25% of AS exons exhibit bimodality and are flanked by longer and more conserved introns harboring distinct cis-regulatory motifs. Bimodal exons are highly dynamic during cellular transitions, preserve translatability, enriched in recently emerged genes and have conserved AS in mammals. Applying Expedition (http://github.com/YeoLab/Expedition) in single cells redefines our estimates and understanding of AS in evolution and biology.
Project description:We sequenced mRNA from mouse E14.5 embryonic cortex to compare gene expression level and alternative splicing events between 2 control (WT) and 2 Qk cKO. A set of tissue specific splicing factors are thought to govern alternative splicing events during neural progenitors (NPC) to neuron transition by regulating neuron specific exons. Here we proposed one such a factor, RNA-binding protein Qki5, which is specifically expressed in neural stem cells. We performed mRNAseq analysis by using mRNAs obtained from developing cerebral cortices in Qk conditional knockout (cKO) mice. Expectedly, we found huge numbers of alternative splicing changes between control and conditional knock-out relative to that of transcripts level changes. Furthermore, DAVID and Meta-scape analysis revealed that affected spliced genes are involved in axon-development and microtubule-based process. Among these, Ninein protein coding mRNA is listed as a Qk protein dependent alternative splicing targets. Interestingly, this exon encodes very long poly-peptides (2,121 nt) and is known as a previously defined dynamic RNA switch during NPC-to-neuron transition. In addition, we validated that the regulation of this large exon is consistent with Qki5 dependent alternative exon inclusion mode obtained from our previous Qki5 HITS-CLIP analysis. Together Qki5 will add to a list factor of alternative splicing in NPC-to-neuron transition.
Project description:This SuperSeries is composed of the following subset Series: GSE34992: Integrative genome-wide analysis reveals cooperative regulation of alternative splicing by hnRNP proteins (splice array) GSE34993: Integrative genome-wide analysis reveals cooperative regulation of alternative splicing by hnRNP proteins (CLIP-Seq) GSE34995: Integrative genome-wide analysis reveals cooperative regulation of alternative splicing by hnRNP proteins (RNA-Seq) Refer to individual Series
Project description:While gene expression dynamics have been extensively catalogued during hematopoietic differentiation in the adult, less is known about transcriptome diversity of human hematopoietic stem cells (HSCs) during development. To characterize transcriptional and post-transcriptional changes in HSCs during development, we leveraged high-throughput genomic approaches to profile miRNAs, lincRNAs, and mRNAs. Our findings indicate that HSCs manifest distinct alternative splicing patterns in key hematopoietic regulators. Detailed analysis of the splicing dynamics and function of one such regulator, HMGA2, identified an alternative isoform that escapes miRNA-mediated targeting. We further identified the splicing kinase CLK3 that, by regulating HMGA2 splicing, preserves HMGA2 function in the setting of an increase in let-7 miRNA levels, delineating how CLK3 and HMGA2 form a functional axis that influences HSC properties during development. Collectively, our study highlights molecular mechanisms by which alternative splicing and miRNA-mediated post-transcriptional regulation impact the molecular identity and stage-specific developmental features of human HSCs.
Project description:While gene expression dynamics have been extensively catalogued during hematopoietic differentiation in the adult, less is known about transcriptome diversity of human hematopoietic stem cells (HSCs) during development. To characterize transcriptional and post-transcriptional changes in HSCs during development, we leveraged high-throughput genomic approaches to profile miRNAs, lincRNAs, and mRNAs. Our findings indicate that HSCs manifest distinct alternative splicing patterns in key hematopoietic regulators. Detailed analysis of the splicing dynamics and function of one such regulator, HMGA2, identified an alternative isoform that escapes miRNA-mediated targeting. We further identified the splicing kinase CLK3 that, by regulating HMGA2 splicing, preserves HMGA2 function in the setting of an increase in let-7 miRNA levels, delineating how CLK3 and HMGA2 form a functional axis that influences HSC properties during development. Collectively, our study highlights molecular mechanisms by which alternative splicing and miRNA-mediated post-transcriptional regulation impact the molecular identity and stage-specific developmental features of human HSCs.
Project description:While gene expression dynamics have been extensively catalogued during hematopoietic differentiation in the adult, less is known about transcriptome diversity of human hematopoietic stem cells (HSCs) during development. To characterize transcriptional and post-transcriptional changes in HSCs during development, we leveraged high-throughput genomic approaches to profile miRNAs, lincRNAs, and mRNAs. Our findings indicate that HSCs manifest distinct alternative splicing patterns in key hematopoietic regulators. Detailed analysis of the splicing dynamics and function of one such regulator, HMGA2, identified an alternative isoform that escapes miRNA-mediated targeting. We further identified the splicing kinase CLK3 that, by regulating HMGA2 splicing, preserves HMGA2 function in the setting of an increase in let-7 miRNA levels, delineating how CLK3 and HMGA2 form a functional axis that influences HSC properties during development. Collectively, our study highlights molecular mechanisms by which alternative splicing and miRNA-mediated post-transcriptional regulation impact the molecular identity and stage-specific developmental features of human HSCs.
Project description:While gene expression dynamics have been extensively catalogued during hematopoietic differentiation in the adult, less is known about transcriptome diversity of human hematopoietic stem cells (HSCs) during development. To characterize transcriptional and post-transcriptional changes in HSCs during development, we leveraged high-throughput genomic approaches to profile miRNAs, lincRNAs, and mRNAs. Our findings indicate that HSCs manifest distinct alternative splicing patterns in key hematopoietic regulators. Detailed analysis of the splicing dynamics and function of one such regulator, HMGA2, identified an alternative isoform that escapes miRNA-mediated targeting. We further identified the splicing kinase CLK3 that, by regulating HMGA2 splicing, preserves HMGA2 function in the setting of an increase in let-7 miRNA levels, delineating how CLK3 and HMGA2 form a functional axis that influences HSC properties during development. Collectively, our study highlights molecular mechanisms by which alternative splicing and miRNA-mediated post-transcriptional regulation impact the molecular identity and stage-specific developmental features of human HSCs.
Project description:While gene expression dynamics have been extensively catalogued during hematopoietic differentiation in the adult, less is known about transcriptome diversity of human hematopoietic stem cells (HSCs) during development. To characterize transcriptional and post-transcriptional changes in HSCs during development, we leveraged high-throughput genomic approaches to profile miRNAs, lincRNAs, and mRNAs. Our findings indicate that HSCs manifest distinct alternative splicing patterns in key hematopoietic regulators. Detailed analysis of the splicing dynamics and function of one such regulator, HMGA2, identified an alternative isoform that escapes miRNA-mediated targeting. We further identified the splicing kinase CLK3 that, by regulating HMGA2 splicing, preserves HMGA2 function in the setting of an increase in let-7 miRNA levels, delineating how CLK3 and HMGA2 form a functional axis that influences HSC properties during development. Collectively, our study highlights molecular mechanisms by which alternative splicing and miRNA-mediated post-transcriptional regulation impact the molecular identity and stage-specific developmental features of human HSCs.
Project description:PQBP1 is a highly conserved protein closely related to neurodegenerative disorders. We identified PQBP1 as an important alternative splicing effector necessary for maintaining normal neuron functions in the brain. In order to explore PQBP1's functions in alternative splicing regulation and neuronal activities, we systematically profiled the alternative splicing targets of PQBP1 in mouse embryonic cortical neurons by RNA-seq. The mRNAs whose alternative splicing are affected by PQBP1 showed tissue-specific functional enrichment especially in neurite outgrowth, with strong Gene Ontology (GO) enrichments for neuron projection development/morphogenesis, dendrite development and axonogenesis. PQBP1's alternative splicing targets are also functionally enriched in RNA splicing, chromatin modification, and ARF signal transduction. We applied RNA-seq to compare the transcriptomes of mock and PQBP1 knockdown mouse embryonic cortical neuron samples.
Project description:Immunological Memory is characterized by a heightened recall response to a previously encountered antigen, resulting from clonal expansion of antigen-specific lymphocytes and differentiation into specialized memory cells. Differentiation of memory B cells involves irreversible encountered antigen, resulting from clonal expansion of antigen-specific lymphocytes and differentiation into specialised memory cells. Differentiation of memory B cells involves irrversible DNA rearrangements and mutations, but differentiation of memory T cells is less understood. In an ENU screen for mouse mutations affecting the proportion of T cells with known memory cell markers, such as the alternative spliced Ptprc isoform CD45RO, we identified an inducible RNA-binding protein of previously unknown function, hnRNPLL (gene symbol Hnrpll), whose mutation abolishes the regulated silencing of CD45RABC exons in T cells and other leukocytes. In the mutant, a single amino acid substitution destabilizes an RNA-recognition domain that binds with micromolar affinity to RNA containing the Ptprc ARS exon silencing sequence. Hnrpll mutations selectively diminishes T cell accumulation in peripheral lymphoid tissues but not proliferation. Exon array analysis of Hnrpll mutant naive and memory T cells reveals an extensive program of alternative mRNA splicing in memory T cells coordinated by hnRNPLL. A remarkable overlap with alternative splicing in neural tissues may reflect a co-opted strategy of RNA rearrangement for achieving immunological memory in T cells. Keywords: Memory; T cell; Immunological memory; Cell differentiation; Alternative splicing; T cell survival; Neuron; Brain; RNA-binding; Exon silencing sequence; Mouse mutation; Exon Microarray