Table 2.

Enzymes that modify the RNA molecules identified in the HFD-fed mice exposed to PCBs and the roles of these modifications

RNA modification	RNA modified	Role	Writer	Eraser	Reader
Am	tRNA snRNAs	Structure and stability, RNA–RNA interaction [12]	FTSJ1 CMTR1 [41, 69, 70]	FTO [33]
m1A	tRNA T-loop, mRNA, mt rRNA		TRMT6 TRMT61A TRMT61B (mt) [9, 71]	ALKBH1 [67], ALKBH3 [72]	YTHDF1–3 [10]
m2,2,7G	mRNA cap		TGS1 [39, 73]
m2,2G	tRNA between the D-loop and anticodon loop		TRM1 (Trmt1) [74]
m5U	tRNA		TRMT2A TRMT2B [43]
m6A	mRNA and U6 RNA	Processing of pri-miRNA to pre-miRNA [75]; lncRNA, circRNAs, mRNA splicing, stability, translation, degradation [13, 57, 76–84]	METTL3 METTL14 WTAP VIRMA RBM15 RBM15B ZC3H13 WTAP CBLL1 METTL16 [55, 84–86]	FTO, ALKBH5 [55]	YTHDF1–3, YTHDC1–2, HNRNPA2B1, IGFBP1–3, PRRC2A, FMR1, ELAVL1, HNRNPC, HNRNPG [10, 79, 87–90]
m6Am	mRNA	Cap modification [52]	PCIF1 [91]	FTO [33]
m7G	mRNA	Cap modification [52, 92, 93]	RNMT METTL1 BUD23 [53, 92]
ms2t6A	tRNA	Position 37 of tRNAs responsible for codons starting with A (ANN)- stabilizes the anticodon loop structure and enhances tRNA-anticodon binding [94]	CDKAL1 [95]
Ψ	tRNA, rRNA, snRNAs, mRNA	Stabilize tRNA structure [96], enhanced mRNA translation [97], role in mRNA not well-understood [98]	PUS1, PUS3, PUS7, PUS7L, PUS10, DKC1, TRUB1 [9, 10, 53]		Incorporation of Ψ suppressed RNA recognition by toll-like receptors TLR2, TLR2, and TLR8 [98]

mt = mitochondrial.