Cytoplasmic m¹A reader YTHDF3 inhibits trophoblast invasion by downregulation of m¹A-methylated IGF1R

N¹-methyladenosine (m¹A) is one of the important post-transcriptional modifications in RNA and plays an important role in promoting translation or decay of m¹A-methylated messenger RNA (mRNA), but the "reader" protein and the exact biological role of m¹A remain to be determined. Here, we identified that nine potential m¹A "reader" proteins including YTH domain family and heterogeneous nuclear ribonucleoprotein by mass spectrometry, and among them, YTH domain-containing protein 3 (YTHDF3), could bind directly to m¹A-carrying RNA. YTHDF3 was then identified to negatively regulate invasion and migration of trophoblast. Mechanistically, we found that the m¹A "reader" YTHDF3 bound to certain m¹A-methylated transcripts, such as insulin-like growth factor 1 receptor (IGF1R), with the combination of iCLIP-seq (individual-nucleotide resolution ultraviolet crosslinking and immunoprecipitation high-throughput sequencing) and m¹A-seq. Furthermore, YTHDF3 could promote IGF1R mRNA degradation and thus inhibit IGF1R protein expression along with its downstream matrix metallopeptidase 9 signaling pathway, consequently decreasing migration and invasion of trophoblast. Thus, we demonstrated that YTHDF3 as an m¹A reader decreased invasion and migration of trophoblast by inhibiting IGF1R expression. Our study outlines a new m¹A epigenetic way to regulate the trophoblast activity, which suggests a novel therapeutic target for trophoblast-associated pregnancy disorders.