LncRNA GAS5 Regulates Myometrial Cell Contractions in an m6A-Dependent Manner.

LncRNAs are engaged in signaling pathways in human physiological and pathological states. However, LncRNAs mediate the onset of human labor still remains unknown. RNA sequencing of lower segment myometrium (in labor vs. not in labor) was analyzed. N6-Methyladenosine (m6A) complexes were detected by RIP and meRIP in human myometrial cells. Plasmid and siRNA transfection was performed, and contraction ability was assessed. RNA pulldown, silver staining, protein mass spectrometry, and RIP were used to identify binding proteins. FISH and immunofluorescence costaining were applied to assess the coexpression. GAS5 was upregulated in human myometrium after labor onset. METTL3 and IGF2BP1 maintained GAS5 RNA stability based on actinomycin assay, thus strengthening the contraction of myometrial cells. RIP and meRIP revealed the binding sites of GAS5 with METTL3 and IGF2BP1, respectively. Furthermore, GAS5 binds TPM4 in cytoplasm of myometrium cells and transports TPM4 to the contraction filaments. m6A RNA modifications were also noted in the mouse myometrium after labor onset. These findings highlighted the critical role of m6A modification in GAS5, providing a new method to explore RNA epigenetic regulatory patterns in human parturition.