Figure 4.

Modification to DNA or RNA through methylation or histone modifications changes the storage and packaging of DNA. Downstream, this can limit transcription. DNA methylation is one of the most studied epigenetic mechanisms, which occurs on CpG islands located in different repetitive genome regions or, more commonly, in promoter regions. Other epigenetic mechanisms known as histone modifications mainly include the methylation, ubiquitylation, acetylation, sumoylation, and phosphorylation of the histone tails. N6-Methyladenosine (m6A) is the most common mRNA modification. m6A modification is conducted by its “readers,” “erasers,” and “writers” to remove, add, or preferentially bind to m6A. m6A methylation occurs at once after pre-mRNA transcription by METTL3-containing methyltransferases, while the demethylation of m6A is by fat mass and obesity associated (FTO) and alpha-ketoglutarate-dependent dioxygenase AlkB homolog 5 (ALKBH5). Reproduced with permission from John Wiley and sons. The following original report was credited: Sang and Deng [26].