METTL3 and depressive disorder: Considering that METTL3, METTL14, and WTAP are core components of the methyltransferase complex, and FTO and ALKBH5 are major demethylases [11,13], it was reported that METTL3, FTO, and ALKBH5 were implicated in the pathology of depression [15,18,23].