Project description:m6A is a widespread RNA modification which plays important roles in the regulation of gene expression. Methods for the global detection of m6A rely on immunoprecipitation of methylated transcripts using m6A antibodies. However, these methods are costly and require large amounts of input RNA, making them prohibitive for many experiments. Here, we describe DART-seq, an antibody-free method for m6A detection which enables transcriptome-wide mapping of m6A residues using low amounts of input material. DART-seq can be used to obtain global m6A maps using as little as 10 nanograms of total RNA and at single-molecule resolution. This method offers several improvements over current techniques and will facilitate detection of m6A in limiting cell and tissue types.
Project description:We present an improved version of DART-seq which utilizes a variant of the YTH domain engineered to achieve enhanced m6A recognition in APO1-YTH (D422N). In addition, we develop in vitro DART-seq and show that it performs similarly to cellular DART-seq and can map m6A in any sample of interest using nanogram amounts of total RNA.
Project description:N6-methyladenosine (m6A) is one of the most abundant mRNA modifications in eukaryotes, related to pivotal RNA metabolism processes. The most popular high-throughput m6A identification method relies on the commercial m6A antibody but suffers from poor reproducibility and limited resolution. Exact location of m6A site is of great vital for understanding the dynamics, functions and machinery of RNA methylation. Here, we developed a precise and high-throughput antibody-independent m6A identification method based on the m6A-sensitive RNA endoribonuclease recognizing ACA motif (m6A-sensitive RNA-Endoribonuclease–Facilitated sequencing or m6A-REF-seq). Whole-transcriptomic single base m6A map generated by m6A-REF-seq displayed a typical distribution pattern with enrichment adjacent to stop codon. Ligase-based and qPCR validation methods were used to confirm the individual m6A sites and quantify the methylation level, reinforcing the high accuracy of m6A-REF-seq. We applied m6A-REF-seq on five tissues from three mammals, showing that m6A sites were conserved and tend to gather together among species. (m6A-REF-seq had been named as Aim-seq.)
Project description:N6-Methyladenosine (m6A) in mRNA regulates almost every stage in the mRNA life cycle, and the development of the high throughput detection of methylated sites in mRNA using MeRIPSeq or miCLIP revolutionized the m6A research field. Both methods are based on immunoprecipitation of fragmented mRNA. However, it is well documented that antibodies often have nonspecific activities, thus verification of identified m6A sites using an antibody-independent method would be highly desirable. Currently such approaches are limited. Here we present RedBaron, an improved biochemical method for the site-specific detection and quantification of m6A in RNA. We demonstrate that the RedBaron method is able to accurately quantify m6A levels at specific transcripts in vivo. We used this assay for the site-specific detection and quantification of m6A within the chicken β-actin (ACTB) zipcode sequence in chicken embryos and in fibroblast cells. We demonstrate that methylation of this site in the β-actin zipcode enhances ZBP1 binding in vitro, whilst methylation of a nearby adenosine abolishes
Project description:We applied chemical-assisted, m6A-SEAL method to profile m6A distributions in the transcriptomes of human and plant cells and compared its results against MeRIPm6A-seq.
Project description:More researches have revealed that N4-acetylcytidine (ac4C) affected a variety of cellular and biological processes. In order to better understand the ac4C roles in biology and disease, we present an antibody-free, fluorine assisted metabolic sequencing method to detect RNA N4-acetylcytidine, called ‘FAM-seq’. We have successfully applied FAM-seq to profile ac4C landscapes in humans. By comparing with the classic ac4C antibody sequencing method, we demonstrated that FAM-seq is a convenient and specific method for transcriptome-wide detection of ac4C. This method holds promise to detect nascent RNA ac4C modifications.
Project description:We used DART-seq to map m6A methylation of RNA in single HEK293T cells. We also used DART-seq to map m6A from bulk RNA from HEK293T cells. Using the 10X Genomics and SMART-seq2 platforms, we sequenced a total of 19,533 experimental and control cells using the 10X Genomics platform, and 1,471 experimental and control cells using SMART-seq2. We then used a Bullseye, a computational pipeline developed within the lab, to identify m6A sites from the C-to-U mutations in bulk and single-cell datasets. We find that most m6A methylation is highly heterogenous from cell-to-cell. RNAs containing m6A methylation, are infrequently methylated, and that most individual sites are rarely methylated within the population. Additionally, we are able to identify differentially methylated RNAs in different cellular states from within a single population, and use m6A methylation information to perform clustering of single cells to find a source of novel cellular heterogeneity.
Project description:Pseudouridine (Ψ) is the most abundant post-transcriptional RNA modification. Various methods have been developed to achieve locus-specific Ψ detection; however, the existing methods often involve radiolabeling of RNA, require advanced experimental skills and can be time-consuming. Herein we report a radiolabeling-free,qPCR-based method to detect locus-specific Ψs in rRNA and mRNA. This method is based on Ψ chemical adduct (Ψ-CMC) induced mutation/deletion during reverse transcription (RT), leading to qPCR products of different melting temperatures. Utilizing high-throughput sequencing, we demonstrate that such misincorporation is a general feature of Ψ-CMC adduct during our improved RT conditions. We validated this method on known Ψ sites in rRNA and showed that the melting curves correlate with the modification level. Moreover, we successfully detected Ψs in mRNA and lncRNA of different abundance, and identified Ψ synthase that targets mRNA. Our facile method takes only 1.5 days to complete, and with slight adjustment it can be applied to detect other epitranscriptomic marks in the transcriptome.