Expanding the RNA alphabet: The expanding world of mRNA modifications

Our understanding of the post-transcriptional modifications that decorate mRNAs, a regulatory layer positioned between DNA and proteins, is in its infancy. Recent advances in genome-wide mapping of pseudouridine (), N6-methyladenosine (m6A), 5-methylcytosine (5mrC), its oxidation product 5-hydroxymethylcytosine (5hmrC), and N1-methyladenosine (m1A) have proven that these modifications unsuspectedly occur from dozens to thousands of different gene transcripts in eukaryotic cells. Therefore epigenetics cannot only be restricted to chromatin modifications, and, when studying gene regulation, one has to consider the expanding kingdom of RNA modifications, also known as the epitranscriptome.