TLDR (True Length of Diverse capped RNAs)-seq: a method for 5’-to-3’ end sequencing of capped full-length RNAs with or without 3’ polyadenylation [R10]
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ABSTRACT: TLDR (True Length of Diverse capped RNAs)-seq: a method for 5’-to-3’ end sequencing of capped full-length RNAs with or without 3’ polyadenylation [R10]
Project description:Analysis and understanding of transcript functions is greatly helped by knowing the full-length sequence of individual RNAs. New long-read sequencing devices such as Oxford Nanopore and Pacbio have the potential to sequence full-length transcripts, but standard methods lack the ability to capture true RNA 5’ ends and selects for poly-adenylated (pA+) transcripts. We present a method that, by utilizing cap-trapping and 3’ end adapter ligation, can sequence transcripts from the exact 5’ end to 3’ end regardless of whether they are poly-adenylated, with no need for ribosomal RNA depletion. We show that the method can faithfully detect 5’ ends, splice junctions and 3’ ends, has high reproducibility between runs and gene expression estimates from the method correlate well with short-read sequencing methods. We also demonstrate that the method can detect and sequence full-length pA- RNAs, including lncRNAs, promoter upstream transcripts (PROMPTs) and enhancer RNAs. TLDR-seq is therefore useful for the characterization of diverse capped RNA species.
Project description:Analysis and understanding of transcript functions is greatly helped by knowing the full-length sequence of individual RNAs. New long-read sequencing devices such as Oxford Nanopore and Pacbio have the potential to sequence full-length transcripts, but standard methods lack the ability to capture true RNA 5’ ends and selects for poly-adenylated (pA+) transcripts. We present a method that, by utilizing cap-trapping and 3’ end adapter ligation, can sequence transcripts from the exact 5’ end to 3’ end regardless of whether they are poly-adenylated, with no need for ribosomal RNA depletion. We show that the method can faithfully detect 5’ ends, splice junctions and 3’ ends, has high reproducibility between runs and gene expression estimates from the method correlate well with short-read sequencing methods. We also demonstrate that the method can detect and sequence full-length pA- RNAs, including lncRNAs, promoter upstream transcripts (PROMPTs) and enhancer RNAs. TLDR-seq is therefore useful for the characterization of diverse capped RNA species.
Project description:TLDR (True Length of Diverse capped RNAs)-seq: a method for 5’-to-3’ end sequencing of capped full-length RNAs with or without 3’ polyadenylation
Project description:Purpose:Up to 80% of the human genome gives rise to “dark matter” RNAs that mainly composes of non-capped RNAs (napRNAs). However, determining the functional impacts and metabolisms of the napRNAs requires identification of their full-length sequences. Method:We developed an approach to globally profile the full-length sequences of napRNAs at single-nucleotide resolution Results:We discovered, for the first time, the stable expressed linear intron RNA (sliRNA), a novel class of snoRNA-intron (snotron) RNAs, a new class of RNA embedded in miRNA spacers (misRNA) and thousands of new exceptional structured ncRNAs and repeat-derived ncRNAs (repeatRNA) in humans and mouse. Importantly, these new napRNAs are dynamic changes in response to various stimuli and biological processes, suggesting that they have potential regulatory functions. Furthermore, we show that functional napRNA FS4, discovered by NAP-seq firstly, promotes HepG2 cell proliferation by interacting with DKC1 to maintain the protein stability. Conclusion:Collectively, our approach establishes a paradigm for mapping and annotating novel class of ncRNAs of many living species.
Project description:Piwi-interacting (pi) RNAs are a class of germline-expressed small RNAs that have been linked to epigenetic programming in metazoa. C. elegans piRNAs known as 21U-RNAs are defined by more than 15,000 genome-encoded species. To explore the origin of 21U-RNAs we employed methods to enrich the 5' ends of Pol II transcripts. We show that a species of capped-short (cs) RNA is frequently expressed bidirectionally at Pol II loci in C. elegans. Interestingly, at annotated 21U-RNA loci, csRNAs originate precisely 2 nt upstream of the mature piRNA species suggesting that csRNAs are piRNA precursors. In addition, we show that csRNAs associated with TS sites genome-wide define a previously overlooked class of 21U-RNA loci, and nearly double the number of piRNA species available for genome surveillance. Our methods should be of general utility in TS site identification and 5' anchored RNA-expression profiling. Identification of capped RNA including capped small RNA and long capped RNA in C. elegans. The mouse data are independent data to test the CapSeq sequencing protocol.
Project description:The 5’ end of a eukaryotic mRNA generally has a methyl guanosine cap (m7G cap) that not only protects the mRNA from degradation but also mediates almost all other aspects of gene expression. Some RNAs in E. coli, yeast, and mammals were recently found to contain an NAD+ cap at their 5’ ends. Here we report development of a new method – NAD tagSeq – for transcriptome-wide identification and quantification of NAD+-capped RNAs (NAD-RNAs). The method uses first an enzymatic reaction and then a click chemistry reaction to label NAD-RNAs with a synthetic RNA tag. The tagged RNA molecules can be enriched and directly sequenced using the Oxford Nanopore sequencing technology. NAD tagSeq not only allows more accurate identification and quantification of NAD-RNAs but can also reveal sequences of whole NAD-RNA transcripts. Using NAD tagSeq, we found that NAD-RNAs in Arabidopsis are mostly produced from a few thousand protein-coding genes, with over 60% of them from fewer than 200 genes. The top 2,000 genes that were found to produce the highest numbers of NAD-RNAs were enriched in the gene ontology terms of responses to oxidative stress and other stresses, photosynthesis, and protein synthesis. For some Arabidopsis genes, over 10% of their transcripts could be NAD-capped. The NAD-RNAs in Arabidopsis have similar overall sequence structures to their canonical m7G-capped mRNAs. The identification and quantification of NAD-RNAs and revealing their sequence features provide essential steps toward understanding functions of NAD-RNAs.
Project description:All eukaryotic mRNAs contain a 7-methylguanosine (m7G) cap which serves as a platform that recruits proteins to support essential biological functions such as mRNA processing, nuclear export and cap-dependent translation. Although the caping is one of the first steps of transcription and uncapped mRNA is not functional, the fate and turnover of uncapped transcripts have not been studied extensively. Here, we employed fast nuclear depletion of the capping enzymes in yeast Saccharomyces cerevisiae to uncover the turnover of transcripts that failed to be capped. We found that the degradation of non-capped mRNA is mainly performed by Xrn1, the exonuclease which is predominantly localized in the cytoplasm, and the fate of such transcripts is determined principally by the abundance of their synthesis. Nuclear depletion of the capping enzymes increased the levels of poorly expressed mRNAs and non-coding RNAs and did not affect the distribution of RNA Polymerase II on chromatin. Overall, our data indicate that mRNAs that failed to be capped are not directed to any specific quality-control pathway and are stochastically degraded.
Project description:CD47 is a marker of self and a signaling receptor for thrombospondin-1 that is also a membrane
component of extracellular vesicles (EVs) released by various cell types. Previous studies identified CD47-dependent functional effects of EVs on target cells, mediated by delivery of their RNA contents, and enrichment of specific subsets of coding and noncoding RNAs in CD47+ EVs. Here, transcriptomic analyses of EVs released by human and murine cells revealed CD47-dependent enrichment of capped microRNAs and mRNAs. Knockdown or loss of CD47 in wild type Jurkat T cells or treatment with thrombospondin-1 enhanced levels of specific capped-RNAs released in EVs, and reexpressing CD47 in null cells decreased their levels. Mass spectrometry and co-immunoprecipitation identified specific interactions of CD47 with components of the exportin-1/Ran nuclear export complex and its known cargo proteins and between the CD47 cytoplasmic adapter ubiquilin-1 and the exportin-1/Ran complex. Interaction with CD47 was inhibited following alkylation of exportin-1 at Cys528 by leptomycin B. Leptomycin B treatment increased levels of cap-dependent RNAs and their association with exportin-1 in EVs released from wild type but not CD47-deficient cells. These results indicate that CD47
regulates the trafficking of cap-dependent RNAs to EVs through physical interactions with the exportin-1/Ran transport complex. Within the files, lmj1038 represents the control pulldown from CD47- JinB8 cells whereas lmj1039 is the CD47+ pulldown from wild-type Jurkat cells.
Project description:We were interested in understanding the cytotoxic effects induced by miR-491-5p in IGROV1-R10 cells IGROV1-R10 cells are chemoresistant ovarian cancer cells - chemoresistance being main cause of therapeutic failure in this disease.