Distinct NSun methylases control cytosine-5 methylation of messenger, mitochondrial and transfer RNA: implications for human diseases
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE66012 | GEO | 2017/02/14
SECONDARY ACCESSION(S): PRJNA275669
REPOSITORIES: GEO
Similar Datasets
Project description:Aberrant post-transcriptional methylation is implicated in a wide range of human diseases, yet the specific enzymes responsible for site- and substrate-specific methylation remain largely unknown. Here, we use our recently developed catalysis-dependent RIP sequencing approach (miCLIP) and RNA bisulfite sequencing to map C5-methylcytosine (m5C) in the human transcriptome. We identified two novel m5C methylases NSun3 and NSun6, both of which have strong substrate specificity. In contrast to the previously characterized NSun2, which displays some preference to methylating transfer RNAs (tRNA), NSun6 predominantly targeted 3’ UTRs of messenger RNAs (mRNA), and NSun3 mainly methylated mitochondrial RNAs (mtRNA). Consistent with the miCLIP-predicted RNA target specificity, whole exome sequencing identified NSUN3 loss-of-function mutations in a patient presenting with combined respiratory chain complex deficiency. Functional studies of the patient fibroblast cell line revealed that loss of the NSun3 protein resulted in severe mitochondrial translation defects, which were rescued by expression of wild-type NSun3. In summary, our results reveal how highly conserved NSun m5C methylases partition their substrate specificities to remodel the sequences of particular ribonucleotide classes.
2017-02-14 | GSE66011 | GEO
Project description:Aberrant post-transcriptional methylation is implicated in a wide range of human diseases, yet the specific enzymes responsible for site- and substrate-specific methylation remain largely unknown. Here, we use our recently developed catalysis-dependent RIP sequencing approach (miCLIP) and RNA bisulfite sequencing to map C5-methylcytosine (m5C) in the human transcriptome. We identified two novel m5C methylases NSun3 and NSun6, both of which have strong substrate specificity. In contrast to the previously characterized NSun2, which displays some preference to methylating transfer RNAs (tRNA), NSun6 predominantly targeted 3’ UTRs of messenger RNAs (mRNA), and NSun3 mainly methylated mitochondrial RNAs (mtRNA). Consistent with the miCLIP-predicted RNA target specificity, whole exome sequencing identified NSUN3 loss-of-function mutations in a patient presenting with combined respiratory chain complex deficiency. Functional studies of the patient fibroblast cell line revealed that loss of the NSun3 protein resulted in severe mitochondrial translation defects, which were rescued by expression of wild-type NSun3. In summary, our results reveal how highly conserved NSun m5C methylases partition their substrate specificities to remodel the sequences of particular ribonucleotide classes.
2017-02-14 | GSE66010 | GEO
Project description:Distinct NSun methylases control cytosine-5 methylation of messenger, mitochondrial and transfer RNA: implications for human diseases
| PRJNA275669 | ENA
Project description:We explore the extent and sources of epigenetic variation in cytosine methylation in natural accessions of the flowering plant, Arabidopsis thaliana, by focusing on the methylation of the major rRNA gene repeats at the two nucleolus organizer regions (NOR). Our findings indicate that natural variation in NOR methylation results from a combination of genetic and epigenetic mechanisms. Genetic variation in rRNA gene copy number and trans-acting modifier loci account for some of the natural variation in NOR methylation. Our results also suggest that divergence and inheritance of epigenetic information, independent of changes in underlying nucleotide sequence, may play an important role in maintaining natural variation in cytosine methylation.
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Project description:Transfer-messenger RNA (tmRNA) is a bifunctional RNA that has properties of a tRNA and an mRNA. tmRNA uses these two functions to release ribosomes stalled during translation and target the nascent polypeptides for degradation. This concerted reaction, known as trans-translation, contributes to translational quality control and regulation of gene expression in bacteria. tmRNA is conserved throughout bacteria, and is one of the most abundant RNAs in the cell, suggesting that trans-translation is of fundamental importance for bacterial fitness. Mutants lacking tmRNA activity typically have severe phenotypes, including defects in viability, virulence, and responses to environmental stresses.
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Project description:Programmed methylation and demethylation of regulatory sequences has been proposed to play a central role in vertebrate development. We report here that the methylation status of the 5' regions of a panel of tissue-specific genes could not be correlated with expression in tissues of fetal and newborn mice. Genes reported to be regulated by reversible methylation were not expressed ectopically or precociously in Dnmt1-deficient mouse embryos under conditions where demethylation caused biallelic expression of imprinted genes and activated transcription of endogenous retroviruses of the IAP class. These and other data suggest that the numerous published expression-methylation correlations may have described not a cause but a consequence of transcriptional activation. A model is proposed under which cytosine methylation represents a biochemical specialization of large genomes that participates in specialized biological functions such as allele-specific gene expression and the heritable transcriptional silencing of parasitic sequence elements, whereas cellular differentiation is controlled by conserved regulatory networks that do not depend on covalent modification of the genome.
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Project description:To better understand the mechanistic basis of aging and its relationship with retinal degeneration, we examined gene expression changes in aging rod photoreceptors. Rod photoreceptor cell death is a feature of normal retinal aging and is accelerated in many retinal degenerative diseases, including AMD, the leading cause of untreatable adult blindness in the United States and other western countries. To our knowledge, the examination of age-related gene expression changes in a specific neuronal cell-type is novel, and it has allowed us to identify significant age-related changes with better resolution than is possible with whole retina samples. We used flow cytometry and a transgenic mouse with GFP-tagged rod photoreceptors to purify this specific cell population, and gene expression changes were evaluated at three time points using microarrays and quantitative RT-PCR. Our results suggest that aging is progressive, beginning even in young adult mice. Although rod photoreceptors are highly specialized neurons, our analyses revealed changes in consensus pathways of aging, including oxidative phosphorylation and stress responses affecting transcription and inflammation. In addition, we identified stress response processes that may be especially relevant for the aging retina and retinal diseases, such as angiogenesis and nuclear receptor signaling pathways that affect retinoid and lipid metabolism. We used flow cytometry and a transgenic mouse with GFP-tagged rod photoreceptors to purify this specific cell population, and gene expression changes were evaluated at three time points using microarrays and quantitative RT-PCR.
2010-06-14 | E-GEOD-22317 | biostudies-arrayexpress
Project description:Mitochondrial DNA (mtDNA) has been reported to contain 5-methylcytosine (5mC) at CpG dinucleotides, as in the nuclear genome, but neither the mechanism generating mtDNA methylation nor its functional significance is known. We now report the presence of 5-hydroxymethylcytosine (5hmC) as well as 5mC in mammalian mtDNA, suggesting that previous studies underestimated the level of cytosine modification in this genome. DNA methyltransferase 1 (DNMT1) translocates to the mitochondria, driven by a mitochondrial targeting sequence located immediately upstream of the commonly accepted translational start site. This targeting sequence is conserved across mammals, and the encoded peptide directs a heterologous protein to the mitochondria. DNMT1 is the only member of the three known catalytically active DNA methyltransferases targeted to the mitochondrion. Mitochondrial DNMT1 (mtDNMT1) binds to mtDNA, proving the presence of mtDNMT1 in the mitochondrial matrix. mtDNMT1 expression is up-regulated by NRF1 and PGC1?, transcription factors that activate expression of nuclear-encoded mitochondrial genes in response to hypoxia, and by loss of p53, a tumor suppressor known to regulate mitochondrial metabolism. Altered mtDNMT1 expression asymmetrically affects expression of transcripts from the heavy and light strands of mtDNA. Hence, mtDNMT1 appears to be responsible for mtDNA cytosine methylation, from which 5hmC is presumed to be derived, and its expression is controlled by factors that regulate mitochondrial function.
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Project description:5-methylcytosine in chromosomal DNA represents a potential source of frequent spontaneous mutation for hyperthermophiles. To determine the relevance of this threat for the archaeon Sulfolobus acidocaldarius, the mode of GGCC methylation by its restriction-modification system, SuaI, was investigated. Distinct isoschizomers of the SuaI endonuclease were used to probe the methylation state of GGCC in native S. acidocaldarius DNA. In addition, the methylation sensitivity of the SuaI endonuclease was determined with synthetic oligonucleotide substrates and modified natural DNAs. The results show that the SuaI system uses N(4) methylation to block cleavage of its recognition site, thereby avoiding the creation of G. T mismatches by spontaneous deamination at extremely high temperature.
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