TABLE 1.

Common modifications of mRNA nucleotides

Symbol	Description	Initial report in mammals
m6A	N6-methyladenosine	✓
Am	2′-O-methyladenosine	✓
m6Am	N6,2′-O-dimethyladenosine	✓
m62Am	N6,N6,2′-O-trimethyladenosine
A-I	Adenosine to inosine	✓
m5C	5-Methylcytidine
Cm	2′-O-methylcytidine	✓
m7G	7-Methylguanosine	✓
Gm	2′-O-methylguanosine	✓
m2,7G	N2,7-dimethylguanosine
m2,2,7G	N2,N2,7-trimethylguanosine
Um	2′-O-methyluridine	✓
ac4c	N4-acetylcytidine
m1A	N1-methyladenosine
m3Um	3,2′-O-dimethyluridine
Ψ	Pseudouridine

Among the most prominent RNA modifications, those that have been linked to senescence thus far are highlighted in bold.

Abbreviation: mRNA, messenger RNA.