METTL3-Mediated m6A RNA Methylation of ZBTB4 Interferes With Trophoblast Invasion and Maybe Involved in RSA

Front Cell Dev Biol. 2022 Jun 14;10:894810. doi: 10.3389/fcell.2022.894810. eCollection 2022.

Abstract

N6-methyladenosine (m6A) was the most abundant modification of mRNA and lncRNA in mammalian cells and played an important role in many biological processes. However, whether m6A modification was associated with recurrent spontaneous abortion (RSA) and its roles were still unclear. Methods: Methylated RNA immunoprecipitation sequencing (MeRIP-Seq) was used to study the global m6A modification pattern in RSAs and controls. RNA sequencing (RNA-Seq) was used to study the level of global mRNA in two groups. Real-time quantitative PCR (RT-qPCR) was used to verify the level of mRNA of METTL3 and ZBTB4. MeRIP-qPCR was conducted to test the level of ZBTB4 m6A modification in two groups. In order to further explore whether ZBTB4 was the substrate of METTL3, the HTR-8/SVneo (HTR-8) cell line was selected for the knockdown and overexpression of METTL3. To study whether METTL3 regulated the ZBTB4 expression by recognizing ZBTB4 mRNA m6A motifs in coding sequences (CDS), dual-luciferase reporter assay was conducted. RNA stability assays using actinomycin D were conducted to study the RNA stability of the HTR-8 cell line with METTL3 overexpression and knockdown. To illustrate the role of METTL3 in the invasion of trophoblast, matrigel invasion assays and transwell migration assays were conducted using the HTR-8 cell line with METTL3 overexpression and knockdown. Results: A total of 65 genes were found with significant differences both in m6A modification and mRNA expression. We found m6A methyltransferase METTL3 was significantly down-regulated in the RSA group. Through gene function analysis, RT-qPCR, MeRIP-qPCR validation experiment, knockdown, and overexpression of METTL3 in the HTR-8 cell line, ZBTB4 was selected as one target of METTL3. Furthermore, we clarified that METTL3 regulated the expression of ZBTB4 by recognizing ZBTB4 mRNA m6A motifs in the CDS using the dual-luciferase reporter assay and METTL3 regulated the invasion of trophoblast by altering the stability and expression of ZBTB4 by RNA stability, matrigel invasion, and transwell migration assays. Conclusion: Our study revealed the mechanism by which METTL3 regulated the stability and expression of ZBTB4 and the trophoblast migration ability of RSA. A new perspective was provided for exploring the mechanism of embryonic development in RSA patients.

Keywords: METTL3; N6-methyladenosine; ZBTB4; recurrent spontaneous abortion; trophoblast invasion.