GO:0070988 demethylation: Mechanism, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0070988 demethylation is the biological process of removing one or more methyl groups from a molecule, encompassing DNA, RNA, histone and small-molecule demethylation.
• Enzymatic demethylation is catalysed by TET dioxygenases for DNA, JmjC-domain histone demethylases for histones, and ALKBH/FTO family enzymes for RNA.
• Active DNA demethylation in plants is initiated by DEMETER/ROS1 family 5-methylcytosine DNA glycosylases and completed by base excision repair.
• In animals, TET-mediated oxidation of 5-methylcytosine generates 5-hydroxymethylcytosine and further oxidized bases that are excised by TDG and repaired.
• Demethylation is dysregulated in cancer, IDH-mutant glioma, diabetic foot ulcers and colorectal cancer, making it a therapeutic and biomarker target.
• CRISPR knockout, point-mutation, knock-in and overexpression models enable causal dissection of demethylation enzymes and their substrates.
Description
Demethylation (GO:0070988) is the biological process that removes one or more methyl groups from a molecule, and it is central to epigenetic and metabolic regulation in eukaryotes. Methyl marks on DNA, histones and RNA are reversible; their removal by dedicated enzymes controls gene expression, genome stability and developmental transitions. Because methylation is a major epigenetic mark, demethylation provides a dynamic counterbalance that allows cells to reset transcriptional states in response to developmental and environmental cues. In plants, active DNA demethylation is essential for gene imprinting, transposon silencing and stress responses. In animals, demethylation of 5-methylcytosine and its oxidized derivatives regulates pluripotency, differentiation and neuronal function. The process also extends beyond nucleic acids: histone demethylation by JmjC-domain enzymes shapes chromatin accessibility and is coupled to metabolic signals such as alpha-ketoglutarate. Researchers study GO:0070988 to understand how cells erase methyl marks, how this erasure goes wrong in disease, and how it can be manipulated therapeutically. This article synthesises the QuickGO definition and verified PubMed literature to outline the mechanisms, key genes, disease links and experimental models for demethylation.
demethylation At A Glance
| GO ID | GO:0070988 |
|---|---|
| GO term | demethylation |
| Ontology | biological_process |
| Synonym | none listed in QuickGO |
| Definition | The process of removing one or more methyl groups from a molecule. |
| Major function | Reversal of methyl marks on DNA, histones, RNA and other molecules to regulate gene expression, chromatin state and metabolism. |
| Key enzyme families | TET dioxygenases, JmjC-domain histone demethylases, ALKBH/FTO RNA demethylases, plant DEMETER/ROS1 glycosylases. |
| Cofactors | Alpha-ketoglutarate, Fe(II), oxygen and ascorbate for dioxygenase-mediated demethylation. |
| Disease relevance | Cancer, IDH-mutant glioma, diabetic foot ulcers, colorectal cancer and plant stress responses. |
What Is GO:0070988?
According to the Gene Ontology, GO:0070988 demethylation is the process of removing one or more methyl groups from a molecule. This definition is intentionally broad: it covers enzymatic and non-enzymatic removal of methyl groups from DNA bases, histone lysine and arginine residues, RNA bases and other methylated substrates. Demethylation is therefore not a single reaction but a family of processes that share the net outcome of decreasing the methylation state of a target molecule.
Why Is demethylation Important in Cell Biology?
Demethylation is important because it provides the erasure arm of reversible methylation, allowing cells to reset epigenetic information and respond to developmental, metabolic and environmental signals. Without demethylation, methyl marks would accumulate irreversibly, disrupting gene expression programmes, transposon control and cellular differentiation. The process is also directly implicated in human disease: mutations in demethylation enzymes or their cofactors alter cancer risk and treatment response, and demethylation status can serve as a biomarker.
• Controls gene expression by removing repressive DNA and histone methyl marks.
• Essential for plant development, imprinting and transposon silencing.
• Regulates pluripotency and differentiation in animals via TET-mediated oxidation of 5-methylcytosine.
• Linked to IDH-mutant glioma, where demethylation-induced differentiation is a therapeutic goal.
• Involved in diabetic foot ulcer pathology through DNA methylation and demethylation imbalance.
• Demethylation triggers cell-free DNA release in colorectal cancer cells, a potential biomarker.
• Reactive oxygen species can drive demethylation and reduce methylmercury accumulation in rice.
• Histone demethylation is coupled to nuclear alpha-ketoglutarate dehydrogenase and metabolic state.
• Provides targets for epigenetic drugs and CRISPR-based functional studies.
• Underpins environmental adaptation and stress responses in plants.
What Happens During demethylation?
Initiation: recognition of methylated substrates
In simple terms: The cell first identifies which methyl marks need to be removed.
Demethylation begins with recognition of methylated substrates by specific enzymes. In plants, DEMETER/ROS1 family 5-methylcytosine DNA glycosylases recognise and excise 5-methylcytosine from DNA. In animals, TET dioxygenases bind 5-methylcytosine and oxidise it to 5-hydroxymethylcytosine and further derivatives. Histone demethylases of the JmjC family recognise methylated lysine residues on histone tails. This substrate recognition step determines specificity and is regulated by chromatin context and metabolic cofactors.
Catalysis: oxidative and glycosylase mechanisms
In simple terms: Enzymes chemically remove the methyl group or convert it into a form that can be excised.
Catalysis proceeds through distinct chemistries. TET enzymes and JmjC histone demethylases are Fe(II)/alpha-ketoglutarate-dependent dioxygenases that oxidise methyl groups, producing formaldehyde and CO2 as by-products. Plant DEMETER/ROS1 glycosylases cleave the glycosidic bond of 5-methylcytosine, generating an abasic site. ALKBH and FTO family enzymes demethylate RNA bases through oxidative mechanisms. Nuclear-localised alpha-ketoglutarate dehydrogenase controls histone demethylation by supplying alpha-ketoglutarate, linking metabolism to chromatin.
Excision and repair of demethylated intermediates
In simple terms: After the methyl mark is removed or converted, the DNA backbone is patched by repair enzymes.
In DNA demethylation, oxidized or excised bases are processed by base excision repair. Plant glycosylases create abasic sites that are cleaved and repaired by AP endonucleases, DNA polymerases and ligases. In animals, TDG excises oxidized 5-methylcytosine derivatives before repair restores unmodified cytosine. This repair step is essential for completing active DNA demethylation and for maintaining genome integrity.
Histone demethylation and chromatin resetting
In simple terms: Methyl marks on histone proteins are removed to open or close chromatin.
Histone demethylation removes methyl groups from lysine residues such as H3K4, H3K9 and H3K27, altering chromatin accessibility and transcription. JmjC-domain demethylases require alpha-ketoglutarate, Fe(II) and oxygen, and their activity is sensitive to metabolic state. Nuclear alpha-ketoglutarate dehydrogenase modulates this process by controlling local alpha-ketoglutarate availability. Histone demethylation is therefore a metabolic-epigenetic interface that influences differentiation and disease.
RNA demethylation and non-CpG demethylation
In simple terms: Methyl marks on RNA and on non-CpG DNA sites are also removed.
RNA demethylation by ALKBH and FTO family enzymes reverses N6-methyladenosine and related marks, affecting RNA stability and translation. Active demethylation of non-CpG moieties in animals is an understudied area that may contribute to gene regulation. In plants, active DNA demethylation has been studied for over two decades and extends beyond CpG contexts. These pathways broaden the functional scope of GO:0070988 beyond canonical CpG DNA demethylation.
Key Genes Involved in GO:0070988 demethylation
The following genes and proteins are experimentally implicated in demethylation (GO:0070988) across DNA, histone and RNA substrates.
| Gene | Major Role | Research Relevance |
|---|---|---|
| TET1 | 5-methylcytosine dioxygenase initiating DNA demethylation | Studied in pluripotency and cancer |
| TET2 | 5-methylcytosine dioxygenase | Frequently mutated in haematological malignancies |
| TET3 | 5-methylcytosine dioxygenase | Implicated in zygotic and neuronal demethylation |
| TDG | Thymine DNA glycosylase excising oxidized methylcytosine | Required for active DNA demethylation |
| ROS1 | Plant 5-methylcytosine DNA glycosylase | Model for active DNA demethylation in plants |
| DME | DEMETER 5-methylcytosine DNA glycosylase | Imprinting and transposon control in plants |
| KDM1A | Flavin-dependent histone demethylase | Chromatin regulation and cancer |
| KDM2A | JmjC-domain histone demethylase | H3K36 demethylation and transcription |
| KDM4A | JmjC-domain histone demethylase | H3K9 demethylation and genome stability |
| KDM5A | JmjC-domain histone demethylase | H3K4 demethylation and differentiation |
| KDM6A | JmjC-domain histone demethylase | H3K27 demethylation and development |
| ALKBH5 | RNA demethylase | N6-methyladenosine regulation |
| FTO | RNA and DNA demethylase | Metabolism and obesity research |
| OGDH | Alpha-ketoglutarate dehydrogenase | Supplies alpha-ketoglutarate for histone demethylation |
| IDH1 | Isocitrate dehydrogenase producing alpha-ketoglutarate | Mutant IDH1 alters demethylation in glioma |
| IDH2 | Isocitrate dehydrogenase producing alpha-ketoglutarate | Mutant IDH2 affects epigenetic state |
How Is demethylation Regulated?
Demethylation is regulated at multiple levels. Enzyme activity depends on cofactors such as alpha-ketoglutarate, Fe(II), oxygen and ascorbate, and nuclear alpha-ketoglutarate dehydrogenase controls histone demethylation by modulating local alpha-ketoglutarate availability. In cancer, mutant IDH1/IDH2 produce 2-hydroxyglutarate, which inhibits alpha-ketoglutarate-dependent demethylases and contributes to a hypermethylated state. DNA demethylation in plants is regulated by developmental and stress signals that control ROS1/DME expression and activity. Reactive oxygen species can also directly promote demethylation in rice, linking redox state to methylmercury accumulation. In colorectal cancer cells, DNA demethylation triggers cell-free DNA release, indicating that demethylation status is coupled to genome instability and biomarker shedding.
demethylation and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| IDH1 | IDH-mutant glioma | Knock-in of IDH1 R132H in glioma cell lines |
| TET2 | Haematological malignancies | Knockout in haematopoietic cells |
| TDG | DNA demethylation deficiency | Knockout in mammalian cells |
| ROS1 | Plant developmental defects | Knockout in Arabidopsis |
| OGDH | Metabolic-epigenetic crosstalk | Knockout or point mutation in cancer cells |
Demethylation in cancer and IDH-mutant glioma
Altered demethylation is a hallmark of several cancers. Mutations in IDH1 or IDH2 produce 2-hydroxyglutarate, which inhibits alpha-ketoglutarate-dependent demethylases and leads to a hypermethylated phenotype in glioma. Enhancing demethylation-induced differentiation has been proposed as a therapeutic strategy in IDH-mutant glioma. In colorectal cancer cells, DNA demethylation triggers cell-free DNA release, suggesting that demethylation status may serve as a biomarker for tumour dynamics. These findings link GO:0070988 directly to cancer epigenetics and treatment response.
Demethylation in diabetic foot ulcers
Diabetic foot ulcers are chronic wounds with dysregulated DNA methylation and demethylation. Targeting DNA methylation and demethylation pathways has been proposed as a therapeutic approach to improve wound healing. This implicates demethylation enzymes and their substrates in tissue repair and metabolic disease.
Demethylation in plants and environmental stress
Active DNA demethylation in plants is essential for development, imprinting and transposon silencing, and has been studied for over 20 years. Reactive oxygen species can drive demethylation and reduce methylmercury accumulation in rice, linking demethylation to food safety and environmental stress. These studies show that GO:0070988 is conserved across kingdoms and relevant to agriculture.
From demethylation-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of TET2 alter DNA demethylation? | TET2 knockout cell line |
| Does mutant IDH1 inhibit demethylation? | IDH1 R132H knock-in glioma cells |
| Is ROS1 required for plant demethylation? | ROS1 knockout Arabidopsis |
| Does OGDH control histone demethylation? | OGDH knockout or point-mutation cells |
| Does demethylation trigger cfDNA release? | Demethylation-treated colorectal cancer cells |
| Can demethylation be enhanced for differentiation? | IDH-mutant glioma differentiation models |
How to Study the demethylation Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Bisulfite sequencing | 5-methylcytosine levels | DNA demethylation profiling |
| Oxidized derivative mapping | TET-mediated intermediates | Active DNA demethylation |
| Chromatin immunoprecipitation | Histone methyl marks | Histone demethylation |
| m6A-seq | RNA methylation | RNA demethylation |
| LC-MS/MS | Nucleoside methylation | Quantitative demethylation |
| Cell-free DNA assay | cfDNA release | Colorectal cancer demethylation |
| Differentiation assay | Cell fate changes | IDH-mutant glioma |
| Glycosylase activity assay | ROS1/DME activity | Plant DNA demethylation |
Measuring DNA demethylation
DNA demethylation can be measured by bisulfite sequencing, which detects 5-methylcytosine conversion, and by oxidized derivative mapping for TET-mediated intermediates. In plants, ROS1/DME activity is assayed by glycosylase activity and locus-specific methylation analysis. In colorectal cancer cells, demethylation-induced cell-free DNA release can be quantified from culture supernatants.
Measuring histone demethylation
Histone demethylation is assessed by western blotting with modification-specific antibodies, mass spectrometry of histone tails, and chromatin immunoprecipitation followed by sequencing. Nuclear alpha-ketoglutarate dehydrogenase activity can be measured enzymatically to link metabolism to demethylation.
Measuring RNA demethylation
RNA demethylation is studied by m6A-seq, LC-MS/MS of nucleosides, and RNA immunoprecipitation of ALKBH5 or FTO. These methods quantify N6-methyladenosine removal and its effects on RNA fate.
Functional and phenotypic assays
CRISPR knockout, point-mutation and overexpression models are used to test causality of demethylation enzymes. Differentiation assays in IDH-mutant glioma and wound-healing assays in diabetic foot ulcer models link demethylation to phenotype. Plant stress and methylmercury accumulation assays test demethylation in rice.
How CRISPR Can Be Used to Study GO:0070988 demethylation
Knockout
CRISPR knockout of demethylation enzymes such as TET2, TDG, ROS1 or OGDH ablates their function and reveals their contribution to DNA, histone or RNA demethylation. Knockout models are used to test whether loss of demethylation alters methylation patterns, gene expression and disease phenotypes.
Point Mutation
Point mutations in catalytic residues of TET, JmjC or ALKBH enzymes can separate catalytic activity from scaffolding functions. IDH1 R132H knock-in is a classic point-mutation model that inhibits demethylation and induces a hypermethylated state in glioma.
Knock-in
Knock-in of tagged demethylation enzymes enables locus-specific chromatin immunoprecipitation and live-cell imaging. Knock-in of disease-associated variants such as IDH1 mutations allows study of demethylation inhibition in an isogenic background.
Overexpression
Overexpression of TET, ROS1, DME or ALKBH enzymes increases demethylation and can trigger differentiation or cell-free DNA release. Overexpression models are useful for testing whether enhanced demethylation is sufficient to change phenotype.
How EDITGENE Supports demethylation Research
Researchers studying demethylation-related genes often need to determine whether a candidate gene is causally involved in removing methyl marks, whether a specific mutation alters catalytic activity, and whether restoring or enhancing demethylation changes disease phenotypes. EDITGENE provides CRISPR-based cell models and screening services to answer these questions with publication-grade rigour.
Contact EDITGENE today to design your custom CRISPR model for demethylation research.
Frequently Asked Questions About demethylation
What is GO:0070988 demethylation?
GO:0070988 demethylation is the biological process of removing one or more methyl groups from a molecule, as defined by the Gene Ontology.
What genes are involved in demethylation?
Key genes include TET1, TET2, TET3, TDG, ROS1, DME, KDM1A, KDM4A, KDM5A, KDM6A, ALKBH5, FTO and OGDH.
How does DNA demethylation work?
DNA demethylation is initiated by TET-mediated oxidation or plant glycosylase excision, followed by base excision repair to restore unmodified cytosine.
What is the difference between DNA and histone demethylation?
DNA demethylation removes methyl groups from cytosine bases, while histone demethylation removes methyl groups from lysine residues on histone tails.
Why is demethylation important in cancer?
Altered demethylation, including IDH mutations that inhibit demethylases, contributes to hypermethylation and tumour phenotypes such as IDH-mutant glioma.
What enzymes catalyse demethylation?
TET dioxygenases, JmjC-domain histone demethylases, ALKBH/FTO RNA demethylases and plant DEMETER/ROS1 glycosylases catalyse demethylation.
How can I study demethylation with CRISPR?
CRISPR knockout, point mutation, knock-in and overexpression models can test causality of demethylation enzymes and their disease relevance.
What diseases are linked to demethylation?
Demethylation is linked to IDH-mutant glioma, colorectal cancer, diabetic foot ulcers and plant stress responses.
What cofactors are needed for demethylation?
Alpha-ketoglutarate, Fe(II), oxygen and ascorbate are required for dioxygenase-mediated demethylation.
Is demethylation reversible?
Yes, demethylation is the erasure arm of reversible methylation and can be counterbalanced by methyltransferases.
Conclusion
GO:0070988 demethylation is a fundamental biological process that removes methyl groups from DNA, histones, RNA and other molecules, thereby shaping gene expression, chromatin state and metabolism. Its dysregulation is implicated in cancer, IDH-mutant glioma, diabetic foot ulcers and plant stress responses, making it a high-value target for functional genomics and therapeutic research. CRISPR-based knockout, point-mutation, knock-in and overexpression models, combined with methylation profiling and bioinformatics, provide a rigorous path to dissect demethylation mechanisms and translate them into disease insights.
References
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- 2. Parrilla-Doblas JT et al.. 2019. Active DNA Demethylation in Plants.. Int J Mol Sci 20(19) PMID: 31546611
- 3. Miller JJ et al.. 2022. Enhancing demethylation-induced differentiation in IDH-mutant glioma.. Neuro Oncol 24(5):724-725 PMID: 35239963
- 4. Zhang H et al.. 2022. Active DNA demethylation in plants: 20 years of discovery and beyond.. J Integr Plant Biol 64(12):2217-2239 PMID: 36478523
- 5. Pessei V et al.. 2024. DNA demethylation triggers cell free DNA release in colorectal cancer cells.. Genome Med 16(1):118 PMID: 39385243
- 6. Tang W et al.. 2025. Demethylation by Reactive Oxygen Species Lowers Methylmercury Accumulation in Rice.. J Agric Food Chem 73(15):8775-8783 PMID: 40181763
- 7. Deng JY et al.. 2023. Targeting DNA methylation and demethylation in diabetic foot ulcers.. J Adv Res 54:119-131 PMID: 36706989
- 8. Lucarelli M et al.. 2019. Active Demethylation of Non-CpG Moieties in Animals: A Neglected Research Area.. Int J Mol Sci 20(24) PMID: 31842376
