Demethylase

About: Demethylase is a research topic. Over the lifetime, 2717 publications have been published within this topic receiving 127412 citations.

Comprehensive Analysis of mRNA Methylation Reveals Enrichment in 3′ UTRs and near Stop Codons

Abstract: Methylation of the N(6) position of adenosine (m(6)A) is a posttranscriptional modification of RNA with poorly understood prevalence and physiological relevance. The recent discovery that FTO, an obesity risk gene, encodes an m(6)A demethylase implicates m(6)A as an important regulator of physiological processes. Here, we present a method for transcriptome-wide m(6)A localization, which combines m(6)A-specific methylated RNA immunoprecipitation with next-generation sequencing (MeRIP-Seq). We use this method to identify mRNAs of 7,676 mammalian genes that contain m(6)A, indicating that m(6)A is a common base modification of mRNA. The m(6)A modification exhibits tissue-specific regulation and is markedly increased throughout brain development. We find that m(6)A sites are enriched near stop codons and in 3' UTRs, and we uncover an association between m(6)A residues and microRNA-binding sites within 3' UTRs. These findings provide a resource for identifying transcripts that are substrates for adenosine methylation and reveal insights into the epigenetic regulation of the mammalian transcriptome.

ALKBH5 Is a Mammalian RNA Demethylase that Impacts RNA Metabolism and Mouse Fertility

Abstract: N(6)-methyladenosine (m(6)A) is the most prevalent internal modification of messenger RNA (mRNA) in higher eukaryotes. Here we report ALKBH5 as another mammalian demethylase that oxidatively reverses m(6)A in mRNA in vitro and in vivo. 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 have increased m(6)A in mRNA and 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 1,551 differentially expressed genes that cover broad functional categories and include spermatogenesis-related mRNAs involved in the p53 functional interaction network. The discovery of this RNA demethylase strongly suggests that the reversible m(6)A modification has fundamental and broad functions in mammalian cells.

Histone demethylation by a family of JmjC domain-containing proteins

Abstract: Covalent modification of histones has an important role in regulating chromatin dynamics and transcription. Whereas most covalent histone modifications are reversible, until recently it was unknown whether methyl groups could be actively removed from histones. Using a biochemical assay coupled with chromatography, we have purified a novel JmjC domain-containing protein, JHDM1 (JmjC domain-containing histone demethylase 1), that specifically demethylates histone H3 at lysine 36 (H3-K36). In the presence of Fe(ii) and alpha-ketoglutarate, JHDM1 demethylates H3-methyl-K36 and generates formaldehyde and succinate. Overexpression of JHDM1 reduced the level of dimethyl-H3-K36 (H3K36me2) in vivo. The demethylase activity of the JmjC domain-containing proteins is conserved, as a JHDM1 homologue in Saccharomyces cerevisiae also has H3-K36 demethylase activity. Thus, we identify the JmjC domain as a novel demethylase signature motif and uncover a protein demethylation mechanism that is conserved from yeast to human.

The Obesity-Associated FTO Gene Encodes a 2-Oxoglutarate–Dependent Nucleic Acid Demethylase

Abstract: Variants in the FTO (fat mass and obesity associated) gene are associated with increased body mass index in humans. Here, we show by bioinformatics analysis that FTO shares sequence motifs with Fe(II)- and 2-oxoglutarate–dependent oxygenases. We find that recombinant murine Fto catalyzes the Fe(II)- and 2OG-dependent demethylation of 3-methylthymine in single-stranded DNA, with concomitant production of succinate, formaldehyde, and carbon dioxide. Consistent with a potential role in nucleic acid demethylation, Fto localizes to the nucleus in transfected cells. Studies of wild-type mice indicate that Fto messenger RNA (mRNA) is most abundant in the brain, particularly in hypothalamic nuclei governing energy balance, and that Fto mRNA levels in the arcuate nucleus are regulated by feeding and fasting. Studies can now be directed toward determining the physiologically relevant FTO substrate and how nucleic acid methylation status is linked to increased fat mass.

Dynamic reprogramming of DNA methylation in the early mouse embryo.

Abstract: Dynamic epigenetic modification of the genome occurs during early development of the mouse. Active demethylation of the paternal genome occurs in the zygote, followed by passive demethylation during cleavage stages, and de novo methylation, which is thought to happen after implantation. We have investigated these processes by using indirect immunofluoresence with an antibody to 5-methyl cytosine. In contrast to previous work, we show that demethylation of the male pronucleus is completed within 4 h of fertilisation. This activity is intricately linked with and not separable from pronucleus formation. In conditions permissive for polyspermy, up to five male pronuclei underwent demethylation in the same oocyte. Paternal demethylation in fertilised oocytes deficient for MBD2, the only candidate demethylase, occurred normally. Passive loss of methylation occurred in a stepwise fashion up to the morulae stage without any evidence of spatial compartmentalisation. De novo methylation was observed specifically in the inner cell mass (ICM) but not in the trophectoderm of the blastocyst and hence may have an important role in early lineage specification. This is the first complete and detailed analysis of the epigenetic reprogramming cycle during preimplantation development. The three phases of methylation reprogramming may have roles in imprinting, the control of gene expression, and the establishment of nuclear totipotency.