N 6-methyladenosine inhibits murine erythroleukemia cell maturation by blocking methylation of RNA and memory via conversion to S-(N 6-methyl)-adenosylhomocysteine

Abstract

We have shown earlier that N 6-methyladenosine (N 6mAdo) 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 N 6mAdo 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, N 6mAdo 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 N 6-mAdo is converted into S-(N 6-methyl)-adenosylhomocysteine (N 6-SAH) in MEL cells, an active intermediate that affects methylation of RNA. Therefore, we conclude that N 6-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 N 6mAdo into N 6-SAH.