Project description:Pseudouridine (Ψ) is an abundant mRNA modification in mammalian transcriptome, but its functions have remained elusive due to the difficulty of transcriptome-wide mapping. We develop a nanopore native RNA sequencing method for quantitative Ψ prediction (NanoPsu) that utilizes native content training, machine learning modeling, and single-read linkage analysis. Biologically, we find interferon inducible Ψ modifications in interferon-stimulated gene transcripts which are consistent with a role of Ψ in enabling efficacy of mRNA vaccines.
Project description:Pseudouridine (Ψ) is an abundant mRNA modification in the mammalian transcriptome, but its function has remained elusive due to the difficulty of transcriptome-wide mapping. We develop nanopore native RNA sequencing for quantitative Ψ analysis that utilizes native content training, machine learning model prediction, and single read coordination. We find interferon inducible Ψ modifications in the interferon stimulated gene transcripts, consistent with a role of Ψ in the efficacy of mRNA vaccines.
Project description:Pseudouridine (Ψ) is an abundant mRNA modification in the mammalian transcriptome, but its function has remained elusive due to the difficulty of transcriptome-wide mapping. We develop nanopore native RNA sequencing for quantitative Ψ analysis that utilizes native content training, machine learning model prediction, and single read coordination. We find interferon inducible Ψ modifications in the interferon stimulated gene transcripts, consistent with a role of Ψ in the efficacy of mRNA vaccines.
Project description:Pseudouridine (Ψ) is the most abundant RNA modification in cellular RNA present in tRNA/rRNA/snRNA and also in mRNA and long noncoding RNA (lncRNA). Elucidation of Ψ function in mRNA/lncRNA requires mapping and quantitative assessment of its modification fraction at single-base resolution. The most widely used Ψ mapping method for mRNA/lncRNA relies on its reaction with N-Cyclohexyl-N'-(2-morpholinoethyl)carbodiimide (CMC), forming an adduct with the Ψ base in RNA that is detectable by reverse transcription (RT) stops. However, this method has not produced consistent Ψ maps in mRNAs; furthermore, available protocols do not lend confidence to the estimation of Ψ fraction at specific sites, which is a crucial parameter for investigating the biological relevance of mRNA modifications. Here we develop a quantitative RT-PCR based method that can detect and quantify the modification fraction of target Ψ sites in mRNA/lncRNA, termed CMC-RT and ligation assisted PCR analysis of Ψ modification (CLAP). The method still relies on RT stop at a CMC-Ψ site, but uses site-specific ligation and PCR to generate two distinct PCR products in the same sample, corresponding to the modified and unmodified site, that are visualized by gel electrophoresis. CLAP not only requires a small amount of cellular RNA to validate Ψ sites but also determines the Ψ fraction semiquantitatively at target sites in mRNA/lncRNA. We determined the Ψ status of four mRNA sites and one lncRNA site whose modification fractions range from 30% to 84% in three human cell lines. Our method enables precise mapping and assessment of Ψ modification levels in low abundance cellular RNAs.
Project description:Pseudouridine (Ψ) is a post-transcriptional RNA modification that alters RNA-RNA and RNA-protein interactions that affect gene expression. Messenger RNA pseudouridylation was recently discovered as a widespread and conserved phenomenon, but the mechanisms responsible for selective, regulated pseudouridylation of specific sequences within mRNAs were unknown. Here, we have revealed mRNA targets for five pseudouridine synthases and probed the determinants of mRNA target recognition by the predominant mRNA pseudouridylating enzyme, Pus1, by developing high-throughput kinetic analysis of pseudouridylation in vitro. Combining computational prediction and rational mutational analysis revealed an RNA structural motif that is both necessary and sufficient for mRNA pseudouridylation. Applying this structural context information predicted hundreds of additional mRNA targets that were pseudouridylated in vivo. These results demonstrate a structure-dependent mode of mRNA target recognition by a conserved pseudouridine synthase and implicate modulation of RNA structure as the probable mechanism to regulate mRNA pseudouridylation.
Project description:N6-methyladenosine (m6A) and pseudouridine (Ψ) are the two most abundant modifications in mammalian mRNA, but the coordination of their biological functions remains poorly understood. We develop a machine learning-based nanopore direct RNA sequencing method (NanoSPA) that simultaneously analyzes m6A and Ψ in the human transcriptome. Applying NanoSPA to polysome profiling, we reveal opposing transcriptomic co-occurrence of m6A and Ψ and synergistic, hierarchical effects of m6A and Ψ on the polysome.