ERα Facilitates Hypoxia-induced Ferroptosis in Placental Trophoblasts by Transcriptionally Activating ACSL4.

Abstract

Problem: Preeclampsia (PE), characterized by hypertension and proteinuria, involves placental dysfunction linked to oxidative stress and ferroptosis. The role of estrogen receptor α (ERα) in hypoxia-induced trophoblast ferroptosis remains unclear.

Method of study: A PE rat model was established using L-NAME injection. Placental tissues were analyzed for protein expression via Western blot. In vitro, HTR-8/SVneo cells were cultured under hypoxic conditions to simulate PE-related hypoxia. ERα was knocked down using siRNAs, and acyl-CoA synthetase long-chain family member 4 (ACSL4) was overexpressed via plasmid transfection. Cell viability, apoptosis, migration, oxidative stress parameters, and ferroptosis-related indicators were assessed using CCK-8, flow cytometry, Transwell assays, and specific biochemical kits. In addition, primary syncytiotrophoblast (STB) cells were isolated from placentas of healthy and PE rats for validation experiments. The transcriptional regulation of ACSL4 by ERα was examined using dual luciferase reporter assays.

Results: In PE rat placentas, ERα and ACSL4 were significantly upregulated, while GPX4 and SLC7A11 were downregulated. In addition, the lipid peroxidation products 4-HNE and MDA were significantly increased in PE placental tissues. Hypoxia induced ferroptosis in HTR-8/SVneo cells, characterized by increased Fe^{2 +} levels, elevated 4-HNE and MDA levels, lipid peroxidation, and activation of the ERα/ACSL4 axis. Knockdown of ERα attenuated hypoxia-induced cell injury, oxidative stress, and ferroptosis, whereas ACSL4 overexpression reversed these protective effects. Furthermore, experiments in primary STB cells isolated from PE rats showed that ERα knockdown similarly alleviated ferroptosis-associated injury and suppressed ACSL4 expression. Mechanistically, ERα bound directly to the ACSL4 promoter and transcriptionally activated its expression.

Conclusions: The ERα-ACSL4 axis plays a critical role in hypoxia-induced ferroptosis in placental trophoblasts. ERα transcriptionally activates ACSL4, promoting lipid peroxidation and ferroptosis, thereby contributing to placental dysfunction in PE. These findings provide a novel theoretical basis for understanding PE pathogenesis and highlight potential therapeutic targets for intervention.