Project description:To identify full-length cap-to-poly(A) mRNA isoforms of CD20 and rule out reverse transcription artifacts which are common in cDNA-seq approaches, long-read Oxford Nanopore direct RNA sequencing was performed on the Raji cell line.
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:We applied direct RNA long read sequencing for characterization of transcripts from constructs inserted into HEK293T mammalian cells with different promoters. Direct RNA sequencing was performed on an Oxford Nanopore GridION device using the Direct Sequencing Kit (SQK-RNA004, date accessed 15 May 2024), MinION RNA flow cell (FLO-MIN00RA), and data pre-processing was performed with MinKNOW (v24.06.10).
Project description:These experiments use a barcoded pool of reporter transcripts, each of which encode the same mScarlet-PPIG_LCD fusion protein, but using different degrees of GA-multivalency via codon bias, and containing a different number of constitutive introns. In order to be able to perform experiments using this pool, it was necessary to perform long-read sequencing of the plasmid pool to relate the barcodes in the 3' ends of the reporter to their gene structure. Therefore, we performed long-read sequencing of the plasmid pool (both the original pool used for transfection and the ePB plasmid used for PiggyBac integration). Furthermore, to determine the splicing patterns of the reporter genes, we transfected the plasmid pool into HeLa cells for 16 hours, then performed targeted long-read sequencing of the reporter plasmids via RT-PCR. Note: the Nanopore adapter ligation strategy means that reads can come in either orientation. To determine the gene architectures and barcodes, we used fuzzy string matching. First we matched to various fixed sequences throughout the reporter transcripts to determine the orientation of the read and that the read spanned the full length of the transcript. Then we used the same string matching strategy to detect the presence of the different intronic or exonic sequences - the gene architecture. Then we extracted the associated unique plasmid barcode associated with that gene architecture. Example reporter sequences can be found here: https://benchling.com/faraway/f_/kXCfddtQ-public-reporter-plasmid-maps/ or alternatively, in Supplemental Table 2 of the bioRxiv submission here: https://www.biorxiv.org/content/10.1101/2023.08.21.554177v1.supplementary-material
Project description:Evaluation of short-read-only, long-read-only, and hybrid assembly approaches on metagenomic samples demonstrating how they affect gene and protein prediction which is relevant for downstream functional analyses. For a human gut microbiome sample, we use complementary metatranscriptomic, and metaproteomic data to evaluate the metagenomic-based protein predictions.
Project description:Ongoing improvements to next generation sequencing technologies are leading to longer sequencing read lengths, but a thorough understanding of the impact of longer reads on RNA sequencing analyses is lacking. To address this issue, we generated and compared two RNA sequencing datasets of differing read lengths -- 2x75 bp (L75) and 2x262 bp (L262) -- and investigated the impact of read length on various aspects of analysis, including the performance of currently available read-mapping tools, gene and transcript quantification, and detection of allele-specific expression patterns. Our results indicate that, while the scalability of read-mapping tools and the cost-effectiveness of long read protocol is an issue that requires further attention, longer reads enable more accurate quantification of diverse aspects of gene expression, including individual-specific patterns of allele-specific expression and alternative splicing. Two RNA-Seq datasets of differing read lengths (2x262 bp and 2x75 bp)
Project description:Clear cell renal cell carcinoma (ccRCC) is the most common form of kidney cancer. To date, long-read RNA sequencing has not been applied to kidney cancer. Here, we used ONT long-read Direct RNA sequencing to profile the transcriptomes of ccRCC cell line RCC4, with and without exposure to pro-inflammatory cytokines. Our results revealed differentially expressed genes induced by the pro-inflammatory cytokines. Moreover, results here revealed potential tumour origin of novel isoforms and genes that were discovered in the archival tumour samples by long-read sequencing.