SRSF5 Regulates Trophoblast Apoptosis by Inhibiting NR2F2 Transcriptional Activity Through MLX Ubiquitin Degradation Mediated by Alternative Splicing in Preeclampsia

The pathogenesis of preeclampsia (PE) is closely related to the dysfunction of placental trophoblast. However, the precise mechanisms underlying placental dysfunction remain inadequately elucidated. The expression of Serine/arginine-rich Splicing Factor 5 (SRSF5) in the placental tissues of PE mice was detected by quantitative real time-PCR (qRT-PCR), western blot and immunohistochemistry (IHC) experiments. The functions of SRSF5 in HTR8/SVneo cells were detected by CCK8, wound healing and transwell assays. TUNEL was used to analyze the apoptosis of HTR8/SVneo cells. Subsequently, alternative splicing events of Max-like protein X (MLX) were identified using RT-PCR and RIP assays. In addition, experiments such as Co-IP and in vivo ubiquitination were used to analyze the molecular mechanism by which SRSF5 regulates apoptosis of HTR8/SVneo cells. SRSF5 was significantly overexpressed in placental tissues of PE mice. Knockdown of SRSF5 induced proliferation, migration and invasion of HTR8/SVneo cells and inhibited cell apoptosis. Mechanistically, silencing SRSF5 could induce the ubiquitination and degradation of MLX through alternative splicing in HTR8/SVneo cells. Furthermore, the knockdown of SRSF5 enhanced the transcriptional activity of nuclear receptor subfamily 2 group F member 2 (NR2F2) via MLX, which contributed to the apoptosis of HTR8/SVneo cells. In summary, the downregulation of SRSF5 enhances the transcriptional activation of NR2F2 and inhibits trophoblast cell apoptosis by facilitating ubiquitination and degradation of MLX protein through alternative splicing, thereby participating in the pathogenesis of PE.