This recently coined term describes a type of gene expression regulation, or a study thereof, that depends on biochemical modifications of mRNA. By analogy to the term epigenetics, described as "functionally relevant changes to the genome that do not involve a change in the nucleotide sequence", epitranscriptomics can be defined as a functionally relevant changes to the transcriptome that do not involve a change in the ribonucleotide sequence. The epitranscriptome, therefore, is defined as the ensemble of such functionally relevant changes. There are several types of RNA modification that impact on gene expression.
m6A describes the methylation of the nitrogen at position 6 of the adenosine base within mRNA. Discovered in 1974, m6A is the most abundant eukaryotic mRNA modification. The term "epitranscriptome" was coined following transcriptome-wide mappings of m6A sites, but does not necessarily exclude other post-transcriptional mRNA modifications.
m6A methylation regulates nuclear export of mature mRNA and mRNA stability. How, and in response to what stimulus, the cell endogeneously regulates the level of m6A methylation remains unclear at present.
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