Project description:Long-read Nanopore cDNA sequencing of polyA-enriched RNA was implemented in a range of adult tissues isolated from cattle, pig, and chicken. These data were used to identify and characterize the expression patterns of full-length transcript isoforms.
Project description:Objectives: To perform long-read transcriptome and proteome profiling of pathogen-stimulated peripheral blood mononuclear cells (PBMCs) from healthy donors. We aim to discover new transcripts and protein isoforms expressed during immune responses to diverse pathogens. Methods: PBMCs were exposed to four microbial stimuli for 24 hours: the TLR4 ligand lipopolysaccharide (LPS), the TLR3 ligand Poly(I:C), heat-inactivated Staphylococcus aureus, Candida albicans, and RPMI medium as negative controls. Long-read sequencing (PacBio) of one donor and secretome proteomics and short-read sequencing of five donors were performed. IsoQuant was used for transcriptome construction, Metamorpheus/FlashLFQ for proteome analysis, and Illumina short-read 3’-end mRNA sequencing for transcript quantification. Results: Long-read transcriptome profiling reveals the expression of novel sequences and isoform switching induced upon pathogen stimulation, including transcripts that are difficult to detect using traditional short-read sequencing. We observe widespread loss of intron retention as a common result of all pathogen stimulations. We highlight novel transcripts of NFKB1 and CASP1 that may indicate novel immunological mechanisms. In general, RNA expression differences did not result in differences in the amounts of secreted proteins. Interindividual differences in the proteome were larger than the differences between stimulated and unstimulated PBMCs. Clustering analysis of secreted proteins revealed a correlation between chemokine (receptor) expression on the RNA and protein levels in C. albicans- and Poly(I:C)-stimulated PBMCs. Conclusion: Isoform aware long-read sequencing of pathogen-stimulated immune cells highlights the potential of these methods to identify novel transcripts, revealing a more complex transcriptome landscape than previously appreciated.
Project description:Adenovirus is a common human pathogen that relies on host cell processes for transcription and processing of viral RNA and protein production. Although adenoviral promoters, splice junctions, and cleavage and polyadenylation sites have been characterized using low-throughput biochemical techniques or short read cDNA-based sequencing, these technologies do not fully capture the complexity of the adenoviral transcriptome. By combining Illumina short-read and nanopore long-read direct RNA sequencing approaches, we mapped transcription start sites and cleavage and polyadenylation sites across the adenovirus genome. In addition to confirming the known canonical viral early and late RNA cassettes, our analysis of splice junctions within long RNA reads revealed an additional 35 novel viral transcripts. These RNAs include fourteen new splice junctions which lead to expression of canonical open reading frames (ORF), six novel ORF-containing transcripts, and fifteen transcripts encoding for messages that potentially alter protein functions through truncations or fusion of canonical ORFs. In addition, we also detect RNAs that bypass canonical cleavage sites and generate potential chimeric proteins by linking separate gene transcription units. Of these, an evolutionary conserved protein was detected containing the N-terminus of E4orf6 fused to the downstream DBP/E2A ORF. Loss of this novel protein, E4orf6/DBP, was associated with aberrant viral replication center morphology and poor viral spread. Our work highlights how long-read sequencing technologies can reveal further complexity within viral transcriptomes.
Project description:Single-cell transcriptomics, reliant on the incorporation of barcodes and unique molecular identifiers (UMIs) into captured polyA+ mRNA, faces a significant challenge due to synthesis errors in oligonucleotide capture sequences. These inaccuracies, which are especially problematic in long-read sequencing, impair the precise identification of sequences and result in inaccuracies in UMI deduplication. To mitigate this issue, we have modified the oligonucleotide capture design, which integrates an interposed anchor between the barcode and UMI, and a 'V' base anchor adjacent to the polyA capture region. This configuration is devised to ensure compatibility with both short and long-read sequencing technologies, facilitating improved UMI recovery and enhanced feature detection, thereby improving the efficacy of droplet-based sequencing methods.
Project description:Analogous to alternative splicing, alternative polyadenylation (APA) has long been thought to result from competition between proximal and distal polyA sites. By Fractionation-seq, we unexpectedly identified several hundred APA genes where their distal polyA isoforms are retained in chromatin/nuclear matrix and proximal polyA isoforms released into the cytoplasm. Global metabolic PAS-seq and Nanopore long-read RNA-seq provided further evidence that the strong distal polyA sites are first processed and the resulting transcripts are anchored in chromatin/nuclear matrix for further processing at proximal polyA sites and removal of certain slowly spliced introns. By engineering an autocleavable ribozyme between the proximal and distal polyA sites, we demonstrated that the distal polyA isoform is indeed the precursor to the proximal polyA isoform. Therefore, unlike alternative splicing, APA sites are recognized independently, rather than competitively, and in many cases, in a sequential manner. This provides a versatile strategy to regulate gene expression in mammalian cells.
Project description:a chromosome-level nuclear genome and organelle genomes of the alpine snow alga Chloromonas typhlos were sequenced and assembled by integrating short- and long-read sequencing and proteogenomic strategy
Project description:Gene-expression noise can influence cell-fate choices across pathology and physiology. However, a crucial question persists: do regulatory proteins or pathways exist that control noise independently of mean expression levels? Resulting from a previous screen, the protein SON was identified as a potential noise regulator. We perform Son KD and utilize (1) total RNA sequencing (RNA-seq) to analyze differences in splicing efficiency of introns upon Son KD; and (2) Nanopore sequencing to analyze changes in isoform usage. These datasets correspond to the aforementioned total RNA-seq and long-read polyA+ cDNA Nanopore sequencing upon Son KD.
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:Long-read RNA sequencing (RNA-seq) is a powerful technology for transcriptome analysis, but the relatively low throughput of current long-read sequencing platforms limits transcript coverage. We present TEQUILA-seq, a versatile, easy-to-implement, and low-cost method for targeted long-read RNA-seq. TEQUILA-seq can be broadly used for targeted sequencing of full-length transcripts in diverse biomedical research settings.
2023-06-06 | GSE213984 | GEO
Project description:Long-read RNA sequencing of HUVEC