Differential m6A, m6Am, and m1A Demethylation Mediated by FTO in the Cell Nucleus and Cytoplasm

Abstract

FTO, the first RNA demethylase discovered, mediates the demethylation of internal N-methyladenosine (mA) and N, 2-O-dimethyladenosine (mA) at the +1 position from the 5' cap in mRNA. Here we demonstrate that the cellular distribution of FTO is distinct among different cell lines, affecting the access of FTO to different RNA substrates. We find that FTO binds multiple RNA species, including mRNA, snRNA, and tRNA, and can demethylate internal mA and cap mA in mRNA, internal mA in U6 RNA, internal and cap mA in snRNAs, and N-methyladenosine (mA) in tRNA. FTO-mediated demethylation has a greater effect on the transcript levels of mRNAs possessing internal mA than the ones with cap mA in the tested cells. We also show that FTO can directly repress translation by catalyzing mA tRNA demethylation. Collectively, FTO-mediated RNA demethylation occurs to mA and mA in mRNA and snRNA as well as mA in tRNA.

To be or not to be modified: Miscellaneous aspects influencing nucleotide modifications in tRNAs

“…ALKBH1 and FTO expression is increased in response to glucose deprivation, which decreases the m 1 A content of certain tRNAs and most probably the stability of tRNA i Met , thereby inhibiting translation initiation. This mechanism might contribute to globally repress translation on glucose deprivation (139,140). These examples highlight the importance of tRNA modification levels in the global control of fundamental cellular functions such as translation and reveal that a demodification enzymatic activity alters modification levels in tRNAs.…”

“…In DNA, ALKBH1 and FTO catalyze demethylation of m 3 C and m 3 T, respectively (144,145). FTO was also reported to catalyze demethylation of m 3 U and m 6 A in mRNA (146,147), and to display a slight tRNA m 3 C demethylation activity in vitro (140). As FTO preferentially catalyzes m 1 A demethylation in stem-loop structures mimicking the T-arm of tRNAs, m 1 A58 is most likely the primary demethylation target of FTO in tRNAs ( Fig.…”

“…ALKBH1 and FTO expression is increased in response to glucose deprivation, which decreases the m 1 A content of certain tRNAs and most probably the stability of tRNA i Met , thereby inhibiting translation initiation. This mechanism might contribute to globally repress translation on glucose deprivation .…”

Mapping N6‐Methyladenosine (m6A) in RNA: Established Methods, Remaining Challenges, and Emerging Approaches

“…The dynamic regulation of m 6 Al evels is achieved by mRNA turnover and the possibilityo fa na ctive demethylation is discussed in the field [28] .F TO and/or AlkBH5 are the two responsible enzymes, although FTO has recently been shown to act preferably on m 6 A m . [4b, 29] These Fe II -a-ketoglutatarate-dependent dioxygenases oxidize the N 6 -methyl group of m 6 Ao r m 6 A m ,l eadingt of ormation of an instable hemiaminal that decomposes to unmethylated Aa nd formaldehyde or might be furtheroxidized to f 6 A, decomposing to Aand formic acid.…”

Cross-talk between m6A and m1A regulators, YTHDF2 and ALKBH3 fine-tunes mRNA expression

“…A large number of studies in the last 6 years have convincingly proven the impact of N 6 -methyl adenosine (m6A) -the most abundant modification on eukaryotic mRNA -on all aspects of RNA metabolism including spicing, stability, translation, microRNA processing (1)(2)(3)(4)(5)(6)(7) and several physiological processes including cancer, immunity and memory (8)(9)(10). The reversible m6A modification is installed by the m6A writer complex (11) containing the catalytic core METTL3 and METTL14 proteins (12) and removed by the m6A erasers ALKBH5 and FTO (13,14). The m6A readers bind m6A RNA targets to mediate their fate.…”