Exon Junction Complex Is a Molecular Compass of N⁶-Methyladenosine Modification

N⁶-methyladenosine (m⁶A) is the most prevalent internal mRNA modification in mammals and plays crucial roles in pre-mRNA splicing, mRNA translation, and mRNA stability. Recent studies from three separate research groups have brought to light the regulation of m⁶A installation by exon junction complexes (EJCs), which are deposited immediately upstream of each exon-exon junction following splicing. These studies have revealed that the EJCs deposited onto mRNAs act as a barrier, limiting the accessibility of METTL3/14 complex (known as m⁶A writer complex), thereby preventing m6A modification in regions of mRNA proximal to the exon-exon junctions. The discovery of this EJC-mediated reshaping of m6A transcriptome paves the way for new research opportunities to comprehend a wide array of molecular, cellular, and physiological events associated with the EJC and m⁶A.