The m6A methyltransferase METTL3 promotes trophoblast cell invasion by regulating MYLK expression

Introduction: The progression of placental diseases such as preeclampsia is closely related to trophoblast dysfunction. Recent studies indicated the dysregulation of N6-methyladenosine (m6A) RNA modification in trophoblast disorders, while the function of METTL3, a methyltransferase of m6A, in trophoblasts remains to be studied.Methods: The expression of METTL3 was determined by real-time PCR and immunoblotting. METTL3 expression in trophoblast cell lines HTR-8/SVneo and JEG-3 was knocked down using shRNA. The invasion of trophoblast cells in Matrigel was determined using xCELLigence. The m6A-containing transcripts was determined by m6A-sequencing in HTR-8/SVneo cells. The myosin light chain kinase (MYLK) gene was transfected into HTR-8/SVneo cells.Results: The expression of METTL3 was downregulated in preeclamptic placentae compared to normal placentae. Knockdown of METTL3 repressed the invasion of extravillous trophoblast cells. Mechanistically, METTL3 pro-moted the stability of MYLK mRNA through m6A modification. Overexpression of MYLK rescued retarded cell invasion by METTL3 depletion.Discussion: Collectively, our results highlight an essential role of METTL3-MYLK axis in trophoblast invasion.