Which metabolites play the most significant roles in influencing DNA methylation?
DNA methylation is a chemical modification of DNA that can affect gene expression. It is caused by the addition of a methyl group (CH3) to a cytosine nucleotide in DNA.
There are many metabolites that can affect DNA methylation. Some of the most studied metabolites include:
1) S-adenosylmethionine (SAM): SAM is a precursor for methyl groups. It is produced by the liver and is used for a variety of purposes, including DNA methylation.
2) Folate: Folate is a B vitamin that is involved in DNA methylation. It is found in leafy green vegetables, fruits, and beans.
3) Vitamin B12: Vitamin B12 is also involved in DNA methylation. It is found in animal products, such as meat, fish, and dairy products.
4) Homocysteine: Homocysteine is an amino acid that can be toxic in high levels. It can interfere with DNA methylation.
5) Methionine: Methionine is an amino acid that is a precursor for SAM. It is found in animal products and some plant-based foods.
The discovery of novel metabolites that influence DNA methylation is opening up exciting new areas of research. Recently, itaconate, a molecule that is directly connected to the central metabolism of mitochondria, has been identified as a promising "immunomodulator" molecule that acts by controlling epigenetic processes.
Itaconate is a compound produced from the tricarboxylic acid (TCA) cycle intermediate cis-aconitate by the enzyme IRG1 (immune-responsive gene 1, aconitase decarboxylase, ACOD1), particularly in activated macrophages. Itaconate has emerged as an important regulator of immune cell metabolism and inflammation. Mechanistically, itaconate and its derivatives can modify proteins through alkylation of cysteine residues, influencing signaling pathways such as the NRF2 antioxidant response and suppressing pro-inflammatory gene expression. In addition, itaconate can affect epigenetic regulation by influencing metabolic pathways that supply cofactors for chromatin-modifying enzymes and by inhibiting certain enzymes involved in inflammatory signaling. Because of these properties, itaconate is often considered an anti-inflammatory metabolite that helps limit excessive immune responses. However, its role is complex: while it can protect tissues from inflammatory damage, it may also contribute to metabolic rewiring in certain pathological contexts. For this reason, itaconate is increasingly studied as a potential therapeutic target and epigenetic regulator, raising the question of whether it ultimately acts as a metabolic “friend” or “foe” in disease.