USP7 represses ferroptosis in trophoblasts in pre-eclampsia by mediating the xCT/GPX4 axis via deubiquitination of NRF2

Objective: Trophoblasts, a unique placental cell type, are sensitive to Ferroptosis. Targeting trophoblast Ferroptosis may be protective against trophoblast damage in patients with pre-eclampsia (PE). Herein, this study probed the role of the deubiquitinating enzyme Ubiquitin-Specific Protease 7 (USP7) in trophoblast Ferroptosis during PE.

Methods: Trophoblasts (HTR-8/SVneo) were subjected to hypoxia treatment to simulate the placental status in PE. USP7 expression in hypoxia-treated HTR-8/SVneo cells was measured. After gain- and loss-of-function assays in hypoxia-treated HTR-8/SVneo cells, biological activities, such as viability, invasion, migration, and Ferroptosis, were detected. NRF2, x-CT, and GPX4 expression levels were examined. The binding between NRF2 and USP7 was analyzed.

Results: USP7 expression was reduced in hypoxia-treated HTR-8/SVneo cells. Cell viability, invasion, and migration were notably decreased, but Ferroptosis was markedly enhanced in hypoxia-treated HTR-8/SVneo cells. Erastin treatment stimulated Ferroptosis, which was blocked by USP7 overexpression or Ferroptosis inhibitor. Mechanistically, NRF2 bound to USP7, and USP7 induced NRF2 deubiquitination and repressed its degradation. Overexpression of USP7 upregulated x-CT and GPX4 in hypoxia-treated HTR-8/SVneo cells. NRF2 knockdown counteracted changes in biological properties and Ferroptosis of hypoxia-treated HTR-8/SVneo cells caused by USP7 overexpression.

Conclusion: USP7-mediated NRF2 deubiquitination stabilizes NRF2 and activates the xCT/GPX4 pathway, suppressing trophoblast Ferroptosis in the setting of PE. This study highlights a promising strategy against trophoblast Ferroptosis and supports the development of new therapies for PE.

Deubiquitination; Ferroptosis; GPX4; NRF2; Pre-eclampsia; Trophoblasts; Ubiquitin-specific protease 7; XCT.