The Deubiquitinating Enzyme USP4 Promotes Trophoblast Dysfunction by Stabilizing RYBP

Previous studies have suggested that impaired spiral artery remodeling, placental dysfunction, and insufficient trophoblast infiltration are the etiology and pathogenesis of Preeclampsia (PE). Ring 1 and YY1 binding protein (RYBP) has been reported to be associated with trophoblast dysfunction. However, the molecular mechanism of RYBP involved in trophoblasts in the pathogenesis of PE is poorly defined. RYBP and Ubiquitin-specific peptidase 4 (USP4) mRNA levels were determined using real-time quantitative polymerase chain reaction (RT-qPCR). RYBP, USP4, p-PI3K, PI3K, p-AKT, and AKT protein levels were measured using western blot assay. Cell viability, proliferation, apoptosis, invasion, and migration were assessed using 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT), 5-ethynyl-2'-deoxyuridine (EdU), flow cytometry, transwell, and wound healing assays. After ubibrowser database analysis, the interaction between USP4 and RYBP was verified using Co-immunoprecipitation (CoIP) assay. RYBP and USP4 expression were upregulated in placental tissues from PE patients. By using JEG-3 and HTR-8/SVneo trophoblast cells, RYBP overexpression or USP4 upregulation could hinder cell viability, proliferation, invasion, migration, and promote apoptosis. Mechanistically, USP4 could trigger the deubiquitination of RYBP and prevent its degradation. In addition, USP4 repressed the PI3K/AKT signaling pathway by regulating RYBP. In total, Decreased USP4-mediated ubiquitination results in an adverse impact on trophoblast function by enhancing RYBP expression, providing a novel therapeutic target for PE.