Project description:Epigenetics and Alternative Splicing are both critical mechanisms guiding gene expression. Several studies have demonstrated that epigenetic marks can influence alternative splicing decisions, but less is known about how alternative splicing may impact epigenetics. Here, we demonstrate that several genes encoding histone modifying enzymes are alternatively spliced downstream of T cell activation signaling pathways, including HDAC7, a gene previously implicated in controlling gene expression programs and differentiation in T cells. Using CRISPR-Cas9 gene editing and cDNA expression, we show that differential inclusion of HDAC7 exon 9 controls the interaction of HDAC7 with protein chaperones with resulting impact on histone modifications and gene expression. Notably, the long isoform, which is favored upon JNK signaling, promotes expression of several critical T cell surface proteins including CD3, CD28, CD69. Thus, we demonstrate that alternative splicing of HDAC7 has a global impact on epigenetics and gene expression, and may contribute to T cell regulation.
Project description:We aimed to study impact of CDC-like kinase (CLK) inhibitor CaNDY on OAS1 splicing manipulation. Our data indicates CaNDY treatment induces switching of OAS1 splice isoforms to provide an increased resistance to SARS-CoV-2 infection.
Project description:Through the RNA interference (RNAi) pathway, small RNAs can influence translation, splicing, transcriptional activation, and transcriptional repression. RNAi is carried out by the targeting Argonaute (Ago) effector protein and the facilitating TNRC6 (also known as GW182) scaffolding protein. Here, we use a suite of gene knockout cell lines and high-throughput sequencing to gather definitive answers about the TNRC6 paralogs, their roles in the cell, and their relation to Ago knockout cell lines. Each subsequent TNRC6 paralog knockout caused more gene changes and few genes overlapped between the single TNRC6 paralog knockouts. In addition, TNRC6 knockout and Ago knockout cell lines’ gene expression profiles are highly correlated with one another, indicating the important regulatory functions these proteins share. Overall we found that in spite of less than 40% sequence identity, TNRC6 paralogs are functionally redundant and can replace one another for core RNAi functions.
Project description:To identify aberrant splicing isoforms and potential neoantigens, we performed full-length cDNA sequencing of lung adenocarcinoma cell lines using a long-read sequencer MinION. We constructed a comprehensive catalog of aberrant splicing isoforms and detected isoform-specific peptides using proteome analysis.
Project description:The specialized corneal epithelium requires differentiated properties, specific for its role at the anterior surface of the eye, thus tight maintenance of the differentiated qualities of the corneal epithelial is essential. Our studies have focused on pinin (PNN), an exon junction component (EJC) that has dramatic implications on corneal epithelial cell differentiation and may act as a stabilizer of the corneal epithelial cell phenotype. Our studies revealed that PNN is involved in both transcriptional repression complexes and the spliceosomal complexes, placing PNN at the fulcrum between chromatin and mRNA splicing. Transcriptome analysis of PNN-knockdown cells revealed clear and reproducible alterations in transcript profiles and splicing patterns of a subset of genes that would significantly impact the epithelial cell phenotype. Here, we further investigate PNN’s role in the regulation of gene expression and alternative splicing (AS) in a corneal epithelial context. We used human corneal epithelial cells (HCET cells) that carry doxycycline-inducible PNN-knockdown shRNA vector and performed RNA-seq to determine differential gene expression and differential AS events. Multiple genes and AS events were identified as differentially expressed between PNN-knockdown and controls cells. Genes up-regulated by PNN-knockdown included a large proportion of genes that are associated with processes associated with enhanced cell migration and ECM remodeling including: MMPs, ADAMs, HAS2, LAMA3, CXCRs and UNC5C. Genes down-regulated in response to PNN depletion included: IGFBP5. FGD3, FGFR2, PAX6, RARG and SOX10. AS events in PNN compared to controls was also more likely to be detected, and uregulated in PNN-knockdowns. In particular, 60% of exon skipping events detected in only one condition were detected in PNN-knockdowns and of the shared exon skipping events, 92% of those differentially expressed were more frequent in the PNN-knockdown. This suggests that in the absence of PNN the epithelial cells are dramatically transformed in the amount and composition of isoforms and that PNN plays a crucial role in the selection of which isoforms differentiating cells produce. Many of the genes affected by PNN-knockdown are known to affect epithelial phenotype. This window into the complexity of RNA splicing in the corneal epithelium implies that PNN exerts broad influence over the regulation and maintenance of epithelial cell phenotype. We used HCET cells that carry doxycycline-inducible PNN knockdown shRNA vector and performed RNA-seq to determine differential gene expression and differential alternative splicing events.
Project description:The aim of this study was to obtain a landscape of alternative splicing (AS) in human hepatocellular carcinoma (HCC). We applied hybrid sequencing by integrating Pacbio long-read and Illumina short-read RNA sequencing data from 8 patient-derived HCC cell lines, and used an immortalized hepatocyte cell line as reference. This study revealed features of annotated and novel splice variants in HCC cells, including transcript length, AS type and protein changes. We also identified novel isoforms and tumor specific isoforms, which may represent potential biomarkers and targets for therapeutic development.
Project description:Alternative splicing (AS) in human genes is widely viewed as a mechanism for enhancing proteomic diversity. AS can also impact gene expression levels without increasing protein diversity by producing “unproductive” transcripts that are targeted for rapid degradation by nonsense-mediated decay (NMD). However, the relative importance of this regulatory mechanism remains underexplored. To better understand the impact of AS-NMD relative to other regulatory mechanisms, we analyzed population-scale genomic data across eight molecular assays, covering various stages from transcription to cytoplasmic decay. We report threefold more unproductive splicing compared to prior estimates using steady-state RNA. This unproductive splicing compounds across multi-intronic genes, resulting in 15% of all transcript molecules from protein-coding genes being unproductive. Leveraging genetic variation across cell lines, we find that GWAS trait-associated loci explained by AS are as often associated with NMD-induced expression level differences as with differences in protein isoform usage. Employing the splice-switching drug risdiplam to manipulate AS at hundreds of genes, we find that ~3/4 of drug-induced isoforms are targeted by NMD, suggesting that most aberrant splicing influences expression levels. Our findings suggest much of the impact of AS is mediated by NMD-induced changes in gene expression rather than diversification of the proteome.
Project description:The specialized corneal epithelium requires differentiated properties, specific for its role at the anterior surface of the eye, thus tight maintenance of the differentiated qualities of the corneal epithelial is essential. Our studies have focused on pinin (PNN), an exon junction component (EJC) that has dramatic implications on corneal epithelial cell differentiation and may act as a stabilizer of the corneal epithelial cell phenotype. Our studies revealed that PNN is involved in both transcriptional repression complexes and the spliceosomal complexes, placing PNN at the fulcrum between chromatin and mRNA splicing. Transcriptome analysis of PNN-knockdown cells revealed clear and reproducible alterations in transcript profiles and splicing patterns of a subset of genes that would significantly impact the epithelial cell phenotype. Here, we further investigate PNN’s role in the regulation of gene expression and alternative splicing (AS) in a corneal epithelial context. We used human corneal epithelial cells (HCET cells) that carry doxycycline-inducible PNN-knockdown shRNA vector and performed RNA-seq to determine differential gene expression and differential AS events. Multiple genes and AS events were identified as differentially expressed between PNN-knockdown and controls cells. Genes up-regulated by PNN-knockdown included a large proportion of genes that are associated with processes associated with enhanced cell migration and ECM remodeling including: MMPs, ADAMs, HAS2, LAMA3, CXCRs and UNC5C. Genes down-regulated in response to PNN depletion included: IGFBP5. FGD3, FGFR2, PAX6, RARG and SOX10. AS events in PNN compared to controls was also more likely to be detected, and uregulated in PNN-knockdowns. In particular, 60% of exon skipping events detected in only one condition were detected in PNN-knockdowns and of the shared exon skipping events, 92% of those differentially expressed were more frequent in the PNN-knockdown. This suggests that in the absence of PNN the epithelial cells are dramatically transformed in the amount and composition of isoforms and that PNN plays a crucial role in the selection of which isoforms differentiating cells produce. Many of the genes affected by PNN-knockdown are known to affect epithelial phenotype. This window into the complexity of RNA splicing in the corneal epithelium implies that PNN exerts broad influence over the regulation and maintenance of epithelial cell phenotype.