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Project description:Sequence- and structure-selective mRNA m5C methylation
| PRJNA625664 | ENA
Project description:mRNA m5C, which has recently been implicated in the regulation of mRNA mobility, metabolism and translation, plays important regulatory roles in various biological events. Two types of m5C sites are found in mRNAs. Type I m5C sites, which contain a downstream G-rich triplet motif and are computationally predicted to be located at the 5' end of putative hairpin structures, are methylated by NSUN2. Type II m5C sites contain a downstream UCCA motif and are computationally predicted to be located in the loops of putative hairpin structures. However, their biogenesis remains unknown. Here we identified NSUN6, a methyltransferase that is known to methylate C72 of tRNAThr and tRNACys, as an mRNA methyltransferase that targets Type II m5C sites. Combining the RNA secondary structure prediction, miCLIP, and results from a high-throughput mutagenesis analysis, we determined the RNA sequence and structural features governing the specificity of NSUN6-mediated mRNA methylation. Integrating these features into an NSUN6-RNA structural model, we identified an NSUN6 variant that largely loses tRNA methylation but retains mRNA methylation ability. Finally, we revealed a weak negative correlation between m5C methylation and translation efficiency. Our findings uncover that mRNA m5C is tightly controlled by an elaborate two-enzyme system, and the protein-RNA structure analysis strategy established may be applied to other RNA modification writers to distinguish the functions of different RNA substrates of a writer protein.
| S-EPMC8288183 | biostudies-literature
Project description:The highly abundant N6-methyladenosine (m6A) RNA modification affects most aspects of mRNA function, yet the precise function of the rarer 5-methylcytidine (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, located in loops of hairpin structures. Knockout and rescue experiments revealed enhanced mRNA and translation levels when NSUN6-targeted mRNAs were methylated. Ribosome profiling further demonstrated that NSUN6-specific methylation correlated with translation termination. While NSUN6 was dispensable for mouse embryonic development, it was down-regulated in human tumours and high expression of NSUN6 indicated better patient outcome of certain cancer types. In summary, our study identifies NSUN6 as a methyltransferase targeting mRNA, potentially as part of a quality control mechanism involved in translation termination fidelity.
| S-EPMC7826283 | biostudies-literature
Project description:Three types of methyltransferases (MTases) generate 5-methylpyrimidine in nucleic acids, forming m5U in RNA, m5C in RNA and m5C in DNA. The DNA:m5C MTases have been extensively studied by crystallographic, biophysical, biochemical and computational methods. On the other hand, the sequence-structure-function relationships of RNA:m5C MTases remain obscure, as do the potential evolutionary relationships between the three types of 5-methylpyrimidine-generating enzymes. Sequence analyses and homology modeling of the yeast tRNA:m5C MTase Trm4p (also called Ncl1p) provided a structural and evolutionary platform for identification of catalytic residues and modeling of the architecture of the RNA:m5C MTase active site. The analysis led to the identification of two invariant residues that are important for Trm4p activity in addition to the conserved Cys residues in motif IV and motif VI that were previously found to be critical. The newly identified residues include a Lys residue in motif I and an Asp in motif IV. A conserved Gln found in motif X was found to be dispensable for MTase activity. Locations of essential residues in the model of Trm4p are in very good agreement with the X-ray structure of an RNA:m5C MTase homolog PH1374. Theoretical and experimental analyses revealed that RNA:m5C MTases share a number of features with either RNA:m5U MTases or DNA:m5C MTases, which suggested a tentative phylogenetic model of relationships between these three classes of 5-methylpyrimidine MTases. We infer that RNA:m5C MTases evolved from RNA:m5U MTases by acquiring an additional Cys residue in motif IV, which was adapted to function as the nucleophilic catalyst only later in DNA:m5C MTases, accompanied by loss of the original Cys from motif VI, transfer of a conserved carboxylate from motif IV to motif VI and sequence permutation.
| S-EPMC419452 | biostudies-literature
Project description:The 5-methylcytosine (m5C) RNA methyltransferase NSUN2 is involved in the regulation of cell proliferation and metastasis formation and is upregulated in multiple cancers. However, the biological significance of NSUN2 in gastric cancer (GC) and the modification of NSUN2 itself have not been fully investigated. Here, we analyzed the expression level of NSUN2 in tissue microarrays containing 403 GC tissues by immunohistochemistry. NSUN2 was upregulated in GC, and that it was a predictor of poor prognosis. NSUN2 promotes the proliferation, migration, and invasion of GC cells in vitro. We also demonstrated that small ubiquitin-like modifier (SUMO)-2/3 interacts directly with NSUN2 by stabilizing it and mediating its nuclear transport. This facilitates the carcinogenic activity of NSUN2. Furthermore, m5C bisulfite sequencing (Bis-seq) in NSUN2-deficient GC cells showed that m5C-methylated genes are involved in multiple cancer-related signaling pathways. PIK3R1 and PCYT1A may be the target genes that participate in GC progression. Our findings revealed a novel mechanism by which NSUN2 functions in GC progression. This may provide new treatment options for GC patients.
| S-EPMC8429414 | biostudies-literature
Project description:This SuperSeries is composed of the SubSeries listed below. Refer to individual Series
2012-12-13 | E-GEOD-39686 | biostudies-arrayexpress
Project description:This SuperSeries is composed of the SubSeries listed below.
2019-03-31 | GSE123527 | GEO
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.
| S-ECPF-GEOD-53370 | biostudies-other
Project description:This SuperSeries is composed of the SubSeries listed below.
2020-06-17 | GSE152640 | GEO
Project description:We report a new method for genome-wide methylation profiling that is able to probe methylation status in both single-copy DNA and interspersed repeats. This method, MethylMAPS, uses methylation-sensitive and -dependent enzymes to fractionate the genome according to methylation state. Methylated and unmethylated fragments are then sequenced with Next-Gen sequencing to map methylated and unmethylated CpG sites in the genome. We have used this method to determine the methylation status of >275 million CpG sites in human and mouse DNA from breast and brain tissues. We conclude that methylation is the default state of most CpG dinucleotides and that a combination of local dinucleotide frequencies, the interaction of repeated sequences, and the presence or absence of histone variants or modifications shields a population of CpG sites (most of which are in and around promoters) from DNA methyltransferases that lack intrinsic sequence specificity.
2010-04-16 | GSE21242 | GEO