P53 and H3K4me2 activate N6‐methylated LncPGCAT‐1 to regulate primordial germ cell formation via MAPK signaling

Long noncoding RNAs (lncRNAs) participate in the formation of primordial germ cells (PGCs); however, the identity of the key lncRNAs and the molecular mechanisms responsible for the formation of PGCs remain unknown. Here, we identify a key candidate lncRNA (lncRNA PGC transcript‐1, LncPGCAT‐1) via RNA sequencing of embryonic stem cells, PGCs, and Spermatogonial stem cells (SSCs). Functional experiments confirmed that LncPGCAT‐1 positively regulated the formation of PGCs by elevating the expression of Cvh and C‐kit while downregulating the pluripotency(Nanog) in vitro and in vivo; PAS staining of genital ridges in vivo also showed that interference with LncPGCAT‐1 can significantly reduce the number of PGCs in genital ridges, while overexpression of LncPGCAT‐1 had the opposite result. The result of luciferase reporter assay combined with CHIP‐qPCR showed that the expression of LncPGCAT‐1 was promoted by the transcription factor P53 and high levels of H3K4me2. Mechanistically, the luciferase reporter assay confirmed that mitogen‐activated protein kinase 1 (MAPK1) was the target gene of LncPGCAT‐1 and gga‐mir‐1591. In the ceRNA system, high levels of N6 methylation of LncPGCAT‐1 enhanced the adsorption capacity of LncPGCAT‐1 for gga‐mir‐1591. Adsorption of gga‐mir‐1591 activated the MAPK1/ERK signaling cascade by relieving the gga‐mir‐1591‐dependent inhibition of MAPK1 expression. Moreover, LncPGCAT‐1 interacted with interleukin enhancer binding factor 3 (ILF3) to regulate the ubiquitination of P53 and phosphorylation of JNK. Interaction with ILF3 resulted in positive self‐feedback regulation of LncPGCAT‐1 and activation of JNK signaling, ultimately promoting PGC formation. Altogether, the study expands our knowledge of the function and molecular mechanisms of lncRNAs in PGC development. A high level of N6‐methylation in LncPGCAT‐1 can enhance the adsorption capacity of LncPGCAT‐1 to gga‐mir‐1591 for activating the MAPA1/ERK signal to regulate the formation of PGC by relieving the inhibition of MAPK1 expression with gga‐mir‐1591. Meanwhile, LncPGCAT‐1 can interact with ILF3 for regulating the ubiquitination of P53 and phosphorylation of JNK to achieve self‐positive feedback regulation of LncPGCAT‐1 and activation of the JNK signal, respectively, for promoting the formation of PGC.