IGF2BP3 Modulates mRNA Splicing and Stability to Promote Trophoblast Progression via Interaction with PDE3A and...

Background: Preeclampsia (PE) is a pregnancy-specific disorder and a leading cause of maternal and fetal morbidity and mortality. Impaired trophoblast invasion is a hallmark of PE, and alternative splicing (AS) is crucial for trophoblast differentiation and placental development. However, the exact mechanisms of AS in PE remain poorly understood. Methods: To elucidate AS-mediated regulatory pathways in PE, a total of 38 fresh-frozen placental samples, including 13 pre-eclampsia samples and 25 normal control samples, were collected from Renmin Hospital of Wuhan University between 1 February and 30 July 2022. We performed transcriptome sequencing of seven PE and seven normal placentas to identify differentially spliced events. After quality control and adapter trimming, raw sequencing reads were aligned to the human reference genome using STAR. Differential exon usage was analyzed using DEXSeq (version 1.36.0), and exons with an adjusted p-value < 0.05 and a fold change greater than 2 or less than 0.5 were considered significantly differentially spliced. Functional assays, including CCK8, colony formation, and cell cycle analyses, were conducted to assess trophoblast proliferation, whereas wound healing and Transwell assays were used to evaluate trophoblast migration and invasion using the HTR-8/SVneo cell line. RNA immunoprecipitation sequencing (RIP-seq) and RNA stability assays were employed to investigate mRNA interactions and stability. Results: Insulin-like growth factor 2 mRNA-binding protein 3 (IGF2BP3) emerged as a key RNA-binding protein associated with alternative splicing regulation, intersecting both AS-related candidate genes and known splicing factors, although it is not a classical splicing factor itself. IGF2BP3 overexpression markedly enhanced HTR-8/SVneo trophoblast proliferation, migration, and invasion while suppressing ROS activation. RNA-seq, RIP-seq, and RNA stability assays revealed that IGF2BP3 directly interacts with and enhances the stability of PDE3A mRNA. Functional rescue experiments confirmed that PDE3A knockdown partially abrogated IGF2BP3-mediated trophoblast progression. Furthermore, miR-196a-5p was identified as a negative regulator of IGF2BP3 via miRNA inhibitor/mimic transfection, qRT-PCR, and functional assays, confirming that miR-196a-5p overexpression downregulates IGF2BP3, thereby impairing trophoblast migration and proliferation. Notably, restoring IGF2BP3 expression reversed these inhibitory effects. Conclusions: Our findings reveal a previously unrecognized regulatory axis in PE in which miR-196a-5p suppresses IGF2BP3 expression, leading to PDE3A mRNA destabilization and impaired trophoblast function. This study offers mechanistic insights into PE pathogenesis and identifies IGF2BP3 as a potential therapeutic target.