Project description:To investigate the effect of HSATIII lncRNA on m6A modification, we performed m6A-RIP(RNA immuno precipitation) RNA-seq from heat shock-exposed HeLa cells upon HSATIII knockdown.
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) has been recently identified as a conserved epitranscriptomic modification of eukaryotic mRNAs, but its features, regulatory mechanisms, and functions in cell reprogramming are largely unknown. Here, we report m6A modification profiles in the mRNA transcriptomes of four cell types with different degrees of pluripotency. Comparative analysis reveals several features of m6A, especially gene- and cell-type-specific m6A mRNA modifications. We also show that microRNAs (miRNAs) regulate m6A modification via a sequence pairing mechanism. Manipulation of miRNA expression or sequences alters m6A modification levels through modulating the binding of METTL3 methyltransferase to mRNAs containing miRNA targeting sites. Increased m6A abundance promotes the reprogramming of mouse embryonic fibroblasts (MEFs) to pluripotent stem cells; conversely, reduced m6A levels impede reprogramming. Our results therefore uncover a role for miRNAs in regulating m6A formation of mRNAs and provide a foundation for future functional studies of m6A modification in cell reprogramming. m6A-seq in ESC, iPSC, NSC and sertoli cells.
Project description:Epigenetic marking of the genome via modifications of DNA and histones is central to the regulation of gene expression. DNA methylation is a well-characterized modification involved in regulating chromatin states. RNA also undergoes modifications. The most prevalent internal modification of mRNA is N6-methyladenosine (m6A) installed co-transcriptionally by the METTL3-METTL14 methyltransferases. This process is an essential post-transcriptional mechanism of gene regulation. Recent evidence links m6A function to histone modifications. Here we reveal a direct connection between m6A and DNA methylation. We find that the DNA methyltransferase DNMT1 interacts both in vitro and in vivo with METTL14 within the METTL3-METTL14 complex. Using genome- and transcriptome-wide mapping, we show that methylated cytosine (5mC) tends to occur in DNA near positions corresponding to m6A sites in mRNAs, especially in gene bodies, this being associated with increased gene expression. This tight co-occurrence of 5mC and m6A appears to be favoured by a high m6A density. METTL3-depleted cells display strong intragenic DNA hypomethylation and reduced genome-wide binding of DNMT1 to DNA as evidenced by ChIP-Seq, this leading to reduced expression of the corresponding genes. We provide further mechanistic insights by showing in vitro that m6A impedes binding of DNMT1 to RNA. Accordingly, transcriptome-wide mapping of DNMT1 in vivo confirms that METTL3-mediated m6A formation interferes with DNMT1 binding to mRNA targets, causing increased gene expression. Together, our results reveal that METTL3-METTL14 favors intragenic DNA methylation by causing DNMT1 to be repelled from mRNA by m6A and targeted to gene bodies, thereby promoting transcriptional activation. They highlight a previously unrecognized layer of gene expression regulation, involving a direct mechanistic link between DNA methylation and RNA modification.
Project description:Here we determine the map of RNA methylation (m6A) in mouse embrionic stem cells, and Mettl3 knock out cells Examination of m6A modification sites on the transcriptome of mouse Embryonic stem cells and Embryonic Mettl3 knock out cells, using a m6A specific antibody.
Project description:The N6-methyladenosine (m6A) is the most abundant internal modification in almost all eukaryotic messenger RNAs, and is dynamically regulated. Therefore, identification of m6A readers is especially important in determining the cellular function of m6A. YTHDF2 has recently been characterized as the first m6A reader that regulates the cytoplasmic stability of methylated RNA. Here we show that YTHDC1 is a nuclear m6A reader and report the crystal structure of the YTH domain of YTHDC1 bound to m6A-containing RNA. We further determined the structure of another YTH domain, YTHDF1, and found that the YTH domain utilizes a conserved aromatic cage to specifically recognize the methyl group of m6A. Our structural characterizations of the YTHDC1-m6A RNA complex also shed light on the molecular basis for the preferential binding of the GG(m6A)C sequence by YTHDC1 and confirm the YTH domain as a specific m6A RNA reader. PAR-CLIP (Photoactivatable-Ribonucleoside-Enhanced Crosslinking and Immunoprecipitation) was applied to human YTHDC1 protein to identify its binding sites.
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