Project description:Here we describe a method to target, multiplex and sequence full-length, native single-molecule the human mitochondrial genome utilizing the RNA-guided DNA endonuclease Cas9.
Project description:Circular RNAs (circRNAs) have been found abundantly expressed in cancer. Their resistance to exonucleases enables them to have potentially stable interactions with with different types of biomolecules. Alternative splicing can create different circRNA isoforms that have different sequences and unequal interaction potentials. The study of circRNA function thus requires knowledge of complete circRNA sequences. Here we describe psirc, a method that can identify full-length circRNA isoforms and quantify their expression levels using RNA sequencing data. We confirm the effectiveness and computational efficiency of psirc using both simulated and actual experimental data. Applying psirc on transcriptome profiles from nasopharyngeal carcinoma and normal nasopharynx samples, we discovered circRNA isoforms differentially expressed between the two groups. Compared to the assumed circular isoforms derived from linear transcript annotations, some of the alternatively spliced circular isoforms have 100 times higher expression and contain fewer microRNA response elements, demonstrating the importance of quantifying full-length circRNA isoforms.
Project description:We report FLAM-seq, a cDNA library preparation method coupled to PacBio single-molecule sequencing for profiling full-length mRNAs including their poly(A) tail.
Project description:We report isoCirc, a long-read sequencing strategy coupled with an integrated computational pipeline to characterize full-length circular RNA (circRNA isoforms) using rolling circle amplification (RCA) followed by long-read sequencing. Applying isoCirc to 12 human tissues, we determined full-length structures and examined tissue specificities of circRNA isoforms in human transcriptomes.
Project description:While numerous studies have described the transcriptomes of EVs in different cellular contexts, these efforts have typically relied on sequencing methods requiring RNA fragmentation, which limits interpretations on the integrity and isoform diversity of EV-encapsulated RNA populations. Furthermore, it has been assumed that mRNA signatures in EVs are likely to be fragmentation products of the cellular mRNA material, and little is known about the extent to which full-length mRNAs are present within EVs. Using Oxford nanopore long-read RNA sequencing, we sought to characterize the full-length polyadenylated (poly-A) transcriptome of EVs released by human chronic myelogenous leukemia K562 cells. We detected 441 and 280 RNAs that were respectively enriched or depleted in EVs. EV-enriched poly-A transcripts consist of a variety of biotypes, including mRNAs, long non-coding RNAs, and pseudogenes. Our analysis revealed that 12.72% of all reads present in EVs corresponded to known full-length transcripts, 65.34% of which were mRNAs. We also observed that for many well-represented coding and non-coding genes, diverse full-length transcript isoforms were present in EV specimens, and these isoforms were reflective-of but often in different ratio compared to cellular samples. Here we report a full-length transcriptome from human EVs, as determined by long-read nanopore sequencing.
Project description:Alternative splicing increases the diversity of transcriptomes and proteomes in metazoans. The extent to which alternative splicing is active and functional in unicellular organisms is less understood. Here we exploit a single-molecule long-read sequencing technique and develop a computational tool, SpliceHunter, to characterize the transcriptome in the meiosis of fission yeast. We reveal 17017 alternative splicing events in 19741 novel isoforms at different stages of meiosis, including antisense and read-through transcripts. Intron retention is the major type of alternative splicing, followed by “alternate intron in exon”. 887 novel transcription units are detected; 60 of the predicted proteins show homology in other species and form theoretical stable structures. We compare the dynamics of novel isoforms based on the number of supporting full-length reads with those of annotated isoforms and explore the translational capacity and quality of novel isoforms. The evaluation of these factors indicates that the majority of novel isoforms are unlikely to be both condition-specific and translatable but the possibility of functional novel isoforms is not excluded. Together, this study highlights the diversity and dynamics at the isoform level in the sexual development of fission yeast.
Project description:Human preimplantation development is a complex process involving extensive remodeling of gene expression. However, the preimplantation embryo transcriptome has only been annotated using short-read sequencing, which fails to capture full-length mRNAs and associated isoform diversity. We present a novel human embryo transcriptome using integrated long- and short-read RNA sequencing data. Our analysis reveals a total of 110,212 novel isoforms transcribed from known genes containing either a novel combination of known splice sites or at least one novel splice site, and 17,964 isoforms transcribed from completely novel genes located either in antisense direction of known genes or in intergenic space.
Project description:Human preimplantation development is a complex process involving extensive remodeling of gene expression. However, the preimplantation embryo transcriptome has only been annotated using short-read sequencing, which fails to capture full-length mRNAs and associated isoform diversity. We present a novel human embryo transcriptome using integrated long- and short-read RNA sequencing data. Our analysis reveals a total of 110,212 novel isoforms transcribed from known genes containing either a novel combination of known splice sites or at least one novel splice site, and 17,964 isoforms transcribed from completely novel genes located either in antisense direction of known genes or in intergenic space.