NONO and LncRNA NEAT1 orchestrate embryo implantation by paraspeckle-dependent CDC42SE1 mRNA nuclear retention.

The successful implantation of an embryo depends on the endometrium's ability to be receptive. However, the molecular regulatory mechanisms involved in the formation of endometrial receptivity remain poorly understood. In this study, we discovered the mRNA NONO and lncRNA nuclear enriched abundant transcript 1 (NEAT1) using RNA sequencing, which are highly expressed in Meishan (MS) pig endometrium on day 18 of pregnancy. The binding of NEAT1 with proteins such as NONO forms the paraspeckles. Functional assays showed that knockdown of the paraspeckle protein NONO inhibited the proliferation, migration, and adhesion of endometrial epithelial cells (EECs). Isobaric tag for relative and absolute quantitation (iTRAQ) results showed that silencing the paraspeckle scaffold NEAT1 altered the expression levels of numerous genes, particularly CDC42SE1 expression. Mechanistically, NEAT1 retained CDC42SE1 mRNA within the nucleus through paraspeckle and inhibited its exonuclear translation. CDC42SE1 suppresses activation of the Phosphatidylinositol 3-kinase/Protein Kinase B (PI3K/AKT) pathway via interacting with GNG2 and CDC42. In vivo assays demonstrated that LV-sh-NONO injection significantly impeded embryo implantation. These findings suggest that NONO and lncRNA NEAT1 play a regulatory role in embryo implantation through paraspeckle-mediated nuclear retention of CDC42SE1, and provide a new potential target for reducing pig embryo loss.