Project description:N6-methyladenosine (m6A) is a widespread reversible chemical modification of RNAs, implicated in many aspects of RNA metabolism. Little quantitative information exists as to either how many transcript copies of particular genes are m6A modified (âm6A levelsâ), or the relationship of m6A modification(s) to alternative RNA isoforms. To deconvolute the m6A epitranscriptome, we developed m6A level and isoform-characterization sequencing (m6A-LAIC-seq). We found that cells exhibit a broad range of non-stoichiometric m6A levels with cell type specificity. At the level of isoform characterization, we discovered widespread differences in use of tandem alternative polyadenylation (APA) sites by methylated and nonmethylated transcript isoforms of individual genes. Strikingly, there is a strong bias for methylated transcripts to be coupled with proximal APA sites, resulting in shortened 3â untranslated regions (3â-UTRs), while nonmethylated transcript isoforms tend to use distal APA sites. m6A-LAIC-seq yields a new perspective on transcriptome complexity and links APA usage to m6A modifications. m6A-LAIC-seq of H1-ESC and GM12878 cell lines, each cell line has two replicates
Project description:N6-methyladenosine (m6A), the most abundant messenger RNA (mRNA) modification, has emerged as a critical post-transcriptional mechanism that regulates various aspect of mRNA metabolism including pre-mRNA processing, mRNA export, mRNA stability and translation efficiency. However the genetics basis of m6A is largely unexplored. In this work, we mapped m6A-QTLs in 60 LCLs and used the resulting tens of thousands of QTLs to provide insights to m6A biology and its contribution to human complex trait.
Project description:N6-methyladenosine (m6A) is the most common prevalent internal modifications found in many of the eukaryotic mRNA and plays an important role in RNA metabolism including pre-mRNA processing, mRNA stability, RNA splicing, RNA export and nuclear retention. Serrate is a component of the Dicer complex, plays as a key factor in RNA metabolism. We here reported SERRATE acts as a key regulator of mRNA m6A modification in Arabidopsis. Loss function of SE results in significant global m6A level reduction in the se-1 mutant comparing to the Col-0. SE positively regulates the transcription of MTA and MTB. In addition, SE physically interacts and functionally works with the m6A writer complex MTA and MTB which affects the binding of m6A methylase to mRNA. Taking together, our data provides a molecular framework that SE modulates m6A mRNA modification in Arabidopsis.
Project description:N6-methyladenosine (m6A) is a widespread internal RNA modification whose function is poorly understood. Here we report that m6A residues within the 5'UTR promote a novel form of cap-independent translation which is mediated through an interaction between m6A residues and the translation initiation factor, eIF3. We present eIF3a PAR-iCLIP data which demonstrate that eIF3 predominantly binds mRNAs within the 5'UTR. eIF3 binding sites are also in proximity to m6A residues within the 5'UTR of cellular mRNAs. Two replicates of eIF3a PAR-iCLIP in HEK293T cells.
Project description:N6-methyladenosine (m6A) is the most prevalent internal modification present in the mRNA of all higher eukaryotes. Here we present that m6A is selectively recognized by human YTH domain family (YTHDF2) protein to regulate mRNA degradation. By using crosslinking and immunoprecipitation, we have identified over 4000 substrate RNA of YTHDF2 with conserved core motif of G(m6A)C. We further estabilshed the role of YTHDF2 in RNA metabolism by a combination of ribosome profiling, RNA sequencing, m6A level quantification and cell-based imaging: the C-terminal domain of YTHDF2 selectively binds to m6A of mRNA and the N-terminal domain is responsive for localizing mRNA from translatable pool to processing body where mRNA decay occurs. PAR-CLIP and RIP was used to identify YTHDF2 binding sites followed by ribosome profling and RNA seq to assess the consequences of YTHDF2 siRNA knock-down
Project description:N6-methyladenosine (m6A) is a widespread reversible chemical modification of RNAs, implicated in many aspects of RNA metabolism. Little quantitative information exists as to either how many transcript copies of particular genes are m6A modified (“m6A levels”), or the relationship of m6A modification(s) to alternative RNA isoforms. To deconvolute the m6A epitranscriptome, we developed m6A level and isoform-characterization sequencing (m6A-LAIC-seq). We found that cells exhibit a broad range of non-stoichiometric m6A levels with cell type specificity. At the level of isoform characterization, we discovered widespread differences in use of tandem alternative polyadenylation (APA) sites by methylated and nonmethylated transcript isoforms of individual genes. Strikingly, there is a strong bias for methylated transcripts to be coupled with proximal APA sites, resulting in shortened 3’ untranslated regions (3’-UTRs), while nonmethylated transcript isoforms tend to use distal APA sites. m6A-LAIC-seq yields a new perspective on transcriptome complexity and links APA usage to m6A modifications.
Project description:N6-methyladenosine (m6A) is one of the most abundant modifications in eukaryotic RNA. Recent mapping of m6A methylomes in mammals, yeast, and plants as well as characterization of m6A methyltransferases, demethylases, and binding proteins have revealed regulatory functions of this dynamic RNA modification. In bacteria, although m6A is present in ribosomal RNA (rRNA), its occurrence in messenger RNA (mRNA) still remains elusive. Here, we used liquid chromatography-mass spectrometry (LC-MS) to calculate the m6A/A ratio in mRNA from a wide range of bacterial species, which demonstrates that m6A is an abundant mRNA modification in tested bacteria. Subsequent transcriptome-wide m6A profiling in Escherichia coli and Pseudomonas aeruginosa revealed a conserved distinct m6A pattern that is significantly different from that in eukaryotes. Most m6A peaks are located inside open reading frames (ORF), and carry a unique consensus motif (GCCAU). Functional enrichment analysis of bacterial m6A peaks indicates that the majority of m6A-modified transcripts are associated with respiration, amino acids metabolism, stress response, and small RNAs genes, suggesting potential regulatory roles of m6A in these pathways. m6A profiling in E.coli and P.aeruginosa mRNA
Project description:N6-methyladenosine (m6A) is the most prevalent internal modification of messenger RNA (mRNA) in higher eukaryotes. Here we report ALKBH5 as a new mammalian demethylase that oxidatively removes the m6A modification in mRNA in vitro and inside cells. This demethylation activity of ALKBH5 significantly affects mRNA export and RNA metabolism as well as the assembly of mRNA processing factors in nuclear speckles. Alkbh5-deficient male mice are characterized by impaired fertility resulting from apoptosis that affects meiotic metaphase-stage spermatocytes. In accordance with this defect, we have identified in mouse testes 1552 differentially expressed genes which cover broad functional categories and include spermatogenesis-related mRNAs involved in the p53 functional interaction network. We show that Alkbh5-deficiency impacts the expression levels of some of these mRNAs, supporting the observed phenotype. The discovery of this new RNA demethylase strongly suggests that the reversible m6A modification plays fundamental and broad functions in mammalian cells. RNA-seq in two cell types
Project description:m6A is a ubiquitous RNA modification in eukaryotes. Transcriptome-wide m6A patterns in Arabidopsis have been assayed recently. However, m6A differential patterns among organs have not been well characterized. The goal of the study is to comprehensively analyze m6A patterns of numerous types of RNAs, the relationship between transcript level and m6A methylation extent, and m6A differential patterns among organs in Arabidopsis. In total, 18 libraries were sequneced. For the 3 organs: leaf, flower and root, each organ has mRNA-Seq, m6A-Seq and Input sequenced. And each sequence has 2 replicats.
Project description:Posttranscriptional and posttranslational modifications play crucial roles in plant immunity. However, how plant fine-tune these two modifications to activate antiviral immunity remains unknown. Here, we report that the m6A methyltransferase TaHAKAI is utilized by wheat yellow mosaic virus (WYMV) to increase viral genomic m6A modification and promotes viral replication. However, TaHAKAI also functions as an E3 ligase that targets the viral RNA silencing suppressor P2 for degradation and inhibits viral infection. A major allele of TaHAKAI in susceptible cultivar reduced the E3 ligase activity but not m6A methyltransferase activity, promoting viral infection. Interestingly, TaHAKAIR attenuates the mRNA stability of TaWPS1, the negative regulator of spike development, to increase panicle length and spikelet number by modulating its m6A modification. Our study reveals a new mechanisms of balancing disease resistance and yield by fine-tuning m6A modification and ubiquitination.