PRDX4 Alleviates Ovarian Aging by Suppressing Endoplasmic Reticulum Stress‑Related Ferroptosis in Granulosa Cells

Background Ferroptosis is recognized as a novel mechanism underlying ovarian aging. Our previous study revealed that PRDX4 in granulosa cells is a key factor in alleviating ovarian aging. This study was designed to investigate the precise mechanism through which PRDX4 alleviates ovarian aging. Methods The naturally aging mice were used as an in vivo model, and Tg-induced senescent KGN cells were used as an in vitro model. The expression of PRDX4 in KGN cells was manipulated via adenoviral vectors (Ad‑Prdx4 for overexpression and Ad‑Prdx4/siRNA for knockdown). Cellular senescence indicators, including senescence-associated proteins (P16 and P21), the SASP, and SA-β-gal activity, were evaluated. Ferroptosis indicators (GPX4, TFRC, and ACSL4), mitochondrial morphology, and ferrous iron levels were analyzed, and the levels of ROS and MDA were also measured. Results In the ovarian tissues of aging mice and Tg-induced senescent KGN cells, ferroptosis significantly increased, as evidenced by mitochondrial damage, increased iron accumulation, increased ROS/MDA/Fe²⁺ levels, downregulated GPX4 expression, and upregulated TFRC expression (p < 0.05). PRDX4 overexpression significantly reduced P16/P21/TFRC/ACSL4 expression, SA-β-gal positivity, and the ROS/MDA levels but increased GPX4 expression (p < 0.05). Alleviating ER stress reversed ferroptosis, by decreasing the TFRC/ACSL4 expression and the ROS/MDA levels (p < 0.05). Importantly, the expected ferroptotic effects of PRDX4 knockdown were rescued by 4-PBA, and the suppressed ferroptotic effects of PRDX4 overexpression were blocked by tunicamycin, indicating that the suppression of ferroptosis sensitivity by PRDX4 in senescent KGN cells is ER stress‑dependent. Conclusion Our findings demonstrate that PRDX4 alleviates the senescent phenotype of granulosa cells and delays ovarian aging through the downregulation of ER stress‑dependent ferroptosis. This protective effect of PRDX4 on the ovary provides deeper insight into ovarian aging mechanisms and highlights 4-PBA as a potential therapeutic agent for promoting female reproductive longevity.