N6-methyladenosine inhibits murine erythroleukemia cell maturation by blocking methylation of RNA and memory via conversion to S-(N6-methyl)-adenosylhomocysteine.

We have shown earlier that N6-methyladenosine (N6mAdo) and other methylated derivatives block commitment of murine erythroleukemia (MEL) cells to terminal erythroid maturation. In this study, we further investigated the mechanism of this blockade. Treatment of MEL cells with N6mAdo inhibited cell growth, prevented accumulation of committed cells, suppressed methylation of total cytoplasmic RNA, and erased the expression of "memory" response, an event that precedes initiation of commitment. Furthermore, N6mAdo increased the level of S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) and altered the SAH/SAM ratio that influences methylation of ribonucleic acid (RNA). Moreover, analysis of the intracellular extracts revealed that N6-mAdo is converted into S-(N6-methyl)-adenosylhomocysteine (N6-SAH) in MEL cells, an active intermediate that affects methylation of RNA. Therefore, we conclude that N6-mAdo prevents induction of MEL cell differentiation by affecting methylation of critical RNA transcripts involved in expression of "memory" and initiation of commitment. It is likely that this inhibition occurs via conversion of N6mAdo into N6-SAH.