Project description:RNA m5C methylation profile of MCF10A and MDA486 by using MeRIP-Seq protocol Immunoprecipitation of Methylated mRNA at Cytosine (m5C) residues: Affinity purified of anti-methyl cytosine (m5C) polyclonal antibody 7ug (Zymo Research, Catalog#A3001-50) was conjugated with protein-A magnetic beads for 2 h at 4°C in end to end rotator. After that, conjugated beads were extensively washed with RNA immunoprecipitation (RIP) wash buffer to remove unbound antibody. Fragmented 25 ug polyA RNA (mRNA) was incubated with m5C conjugated beads for overnight at 4°C in in the rotating platform in RIP buffer. RIP was done using Megna RNA Immunoprecipitation kit (Millipore, Catalog#17-700). m5C mRNA-immune bead complex was treated with proteinase K buffer to release m5C mRNA from the conjugated antibody. To isolate m5C, mRNA was treated with phenol:chloroform:isoamyl and mixed with 400 ul of chloroform, which was centrifuged at 14000 rpm for 10 minutes to separate aqueous phase. The aqueous phase was ethanol precipitated at -80°C for overnight, to get m5C mRNA. This precipitated m5C mRNA pellet was washed twice with 70% ethanol and air dried. Finally, m5C mRNA pellet was dissolved in nuclease free Water. The m5C mRNA integrity and conentration was quantified by bioanalyzer (Agilent) and Qubit 2.0 flurometer (Invitrogen). The fragmented mRNA was used by following TruSeq RNA Sample Preparation Guide to develop RNA-Seq library for sequencing.
Project description:Methylation is the most common internal modification in mRNA. While the highly abundant N6-methyladonsine (m6A) modification affects most aspects of mRNA function, the precise functions of the rarer 5-methylcytosine (m5C) remains largely unknown. Here, we map m5C in the human transcriptome using methylation-dependent individual-nucleotide resolution cross-linking and immunoprecipitation (miCLIP) combined with RNA bisulfite sequencing. We identify NSUN6 as a methyltransferase with strong substrate specificity towards mRNA. NSUN6 primarily targeted three prime untranslated regions (3’UTR) at the consensus sequence motif CTCCA. Knockout and rescue experiments revealed that only mRNA methylation sites containing the consensus motif depended on the presence of NSUN6. Furthermore, ribosome profiling demonstrated that NSUN6-specific consensus motifs marked translation termination. However, even though NSUN6-methylated mRNAs were reduced in NSUN6 knockout cells, NSUN6 was dispensable for mouse embryonic development. Thus, our study identifies NSUN6 as methyltransferase targeting mRNA in a sequence- and structure-specific manner.
Project description:Methylation of carbon 5 in cytosine (5-methylcytosine; m5C) is a well-characterized DNA modification, and is also predominantly reported in highly abundant noncoding RNAs, such as rRNA and tRNA, in both prokaryotes and eukaryotes. However, the distribution and biological functions of m5C in plant mRNAs remain largely unknown. Here we develop an m5C RNA immunoprecipitation followed by deep sequencing approach (m5C-RIP-seq) to achieve transcriptome-wide profiling of RNA m5C in Arabidopsis thaliana. Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) and dot blot analyses reveal a dynamic pattern of m5C mRNA modification in various tissues and at different developmental stages. m5C-RIP-seq analysis identifies 6,045 putative m5C peaks in 4,465 expressed genes in young seedlings. m5C is enriched in coding sequences with two peaks located immediately after start codons and before stop codons, and is associated with mRNAs with low translation activity. We further show that a RNA (cytosine-5)-methyltransferase, tRNA specific methyltransferase 4B (TRM4B), exhibits the m5C mRNA methyltransferase activity. Mutations in TRM4B display defects in root development and decreased m5C levels in root mRNA. Furthermore, TRM4B affects transcript levels of the genes involved in root development, which is positively correlated with their mRNA stability and m5C levels. Our results suggest that m5C in mRNA is a new epitranscriptome marker widely distributed in plant genes, and that regulation of this modification is an integral part of gene regulatory networks underlying plant development.
Project description:A common mRNA modification is 5-methylcytosine (m5C), whose role in gene-transcript processing and cancer remains unclear. Here we identify Serine/arginine-Rich Splicing Factor 2 (SRSF2) as a reader of m5C, and impaired SRSF2 m5C binding as a potential contributor to leukemogenesis. Structurally, we identify residues involved in m5C recognition and in the impact of the prevalent leukemia-associated mutation SRSF2P95H. We show that SRSF2 binding and m5C colocalize within transcripts. Furthermore, knocking down the m5C writer NSUN2 decreases mRNA m5C, reduces SRSF2 binding, and alters RNA splicing. We also show that the SRSF2P95H mutation impairs the ability of the protein to read m5C-marked mRNA, notably reducing its binding to key leukemia-related transcripts in leukemic cells. In leukemia patients, low NSUN2 expression leads to mRNA m5C hypomethylation and, combined with SRSF2P95H, predicts poor outcomes. Altogether, we highlight an unrecognized mechanistic link between epitranscriptomics and a key oncogenesis driver.
Project description:To investigate the function of TET2 as an mRNA m5C demethylase in the development of acute myeloid leukemia (AML), we conducted RNA bisulfite sequencing of mRNA samples enriched from AML cells carrying Tet2+/+ versus Tet2-/- with actinomycin D treatment at different time point.
Project description:We report the application of RNA bisulfite sequencing(RNA-BS-seq) technology for high-throughput profiling of mouse neuron. Here, we successfully constructed a neuronal oxygen-glucose deprivation/reoxygenation (OGD/R) model,1.5 hours and 3 hours respectively, and obtained an overview of the transcriptome-wide m5C profiles using RNA-BS-seq. We discovered that the distribution of neuronal m5C modifications was highly conserved, significantly enriched in CG-rich regions and concentrated in the mRNA translation initiation regions. After OGD/R, modification level of m5C increased, whereas the number of methylated mRNA genes decreased. The amount of overlap of m5C sites with the binding sites of most RBPs increased significantly, except for that of the RBM3-binding protein. Moreover, hypermethylated genes in neurons were significantly enriched in pathological processes, and the hub hypermethylated genes RPL8 and RPS9 identified by the protein-protein interaction (PPI) network were significantly related to cerebral injury. This study identified novel m5C mRNAs associated with ischemia-reperfusion in neurons, providing valuable perspectives for future studies on the role of the RNA methylation in cerebral ischemia-reperfusion injury.
Project description:5-methylcytosine (m5C) is a prevalent RNA modification crucial for gene expression regulation. However, accurate and sensitive m5C sites identification remains challenging due to severe RNA degradation and reduced sequence complexity during bisulfite sequencing (BS-seq). Here, we report m5C-TAC-seq, a bisulfite-free approach combining TET-assisted m5C-to-f5C oxidation with selective chemical labeling, therefore enabling direct base-resolution m5C detection through pre-enrichment and C-to-T transitions at m5C sites. With m5C-TAC-seq, we comprehensively profiled the m5C methylomes in human and mouse cells, identifying a substantially larger number of confident m5C sites. Through perturbing potential m5C methyltransferases, we deciphered the responsible enzymes for most m5C sites, including the characterization of NSUN5's involvement in mRNA m5C deposition. Additionally, we characterized m5C dynamics during mESC differentiation. Notably, the mild reaction conditions and preservation of nucleotide composition in m5C-TAC-seq allow the m5C detection in chromatin-associated RNAs. The accurate and robust m5C-TAC-seq will advance research into m5C methylation functional investigation.
Project description:Organ-selective delivery of messenger RNA (mRNA) is critical for fulfilling the therapeutic potential of mRNA-based gene and protein replacement technologies. Despite clinical advances in hepatic delivery of mRNA using lipid nanoparticles (LNPs), strategies for extrahepatic organ-selective mRNA delivery remain underexplored. Here, we report a strategy, termed peptide-encoded organ-selective targeting (POST), that allows digital programming of LNPs, through surface engineering with specific amino acid sequences (POST codes), to deliver mRNA to extrahepatic organs after intravenous administration. Our molecular dynamics simulations also suggest the optimized fracture mechanics of peptide-protein assembly as a mechanism underlying sequence-dependent association between POST code and potentially organ-targeting corona proteins. POST codes are also compatible with organ-selective delivery of different ribonucleic acids and multiple gene editing machineries. This “POST code” platform presents a theoretically unlimited modular repertoire for LNP surface engineering for directing organ-tropism, thereby providing opportunities to broaden the scope and versatility of organ-selective mRNA delivery.
Project description:The biotin labeled DNA:RNA hybrids with or without RNA m5C modification were incubated with lysates of 293 cells treated with H2O2, and were pulled down by Streptavidin. The proteins pulled down by the empty beads control, unmodified or m5C-modified hybrids were analyzed by mass spectrometry