Spermidine Shields Ovarian Cells From Copper-Triggered Cell Death, Study Finds

Copper is an essential trace element, but new research suggests that when it builds up inside the ovary, it can push the cells that nurture developing eggs into a distinctive form of self-destruction. A team at Sichuan Agricultural University reports that spermidine, a naturally occurring polyamine long associated with cellular rejuvenation, can protect pig granulosa cells from this copper-driven death by acting on a specific microRNA-protein axis. The findings, published in Cell Death Discovery, offer a mechanistic window into how trace metal stress may contribute to follicular atresia, the degenerative process that eliminates the vast majority of follicles in the mammalian ovary.

The form of cell death at the center of the study is cuproptosis, a regulated death program first described in 2022 and distinct from apoptosis, necroptosis, and ferroptosis. Cuproptosis is triggered when copper binds directly to lipid-acylated components of the tricarboxylic acid cycle inside mitochondria. That binding causes the lipoylated proteins to aggregate, overwhelming the cell’s protein quality control systems. At the same time, copper stress depletes iron-sulfur cluster proteins, which are essential cofactors for enzymes involved in respiration and DNA maintenance. The result is a catastrophic collapse of mitochondrial metabolism that cannot be rescued by ordinary antioxidant defenses.

Granulosa cells are particularly vulnerable to this kind of metabolic injury. These somatic cells surround the oocyte within the ovarian follicle, supplying it with energy substrates, biosynthetic precursors, and survival signals. Their own energy metabolism and intense biosynthetic activity depend heavily on healthy mitochondria, so any program that dismantles mitochondrial function strikes at the heart of what granulosa cells do. When granulosa cells die, the follicle becomes atretic and is ultimately lost from the reproductive pool, which is why understanding the triggers of granulosa cell death matters for fertility in livestock and, potentially, in humans.

The researchers began by examining atretic follicles from pigs, a species whose ovarian physiology closely mirrors that of humans in several respects. In the granulosa cells of these degenerating follicles, they found elevated levels of SLC31A1, the copper transporter responsible for importing copper into cells, along with increased copper concentrations in both the granulosa cells themselves and the surrounding follicular fluid. These changes were accompanied by a telling molecular signature: reduced abundance of FDX1, the protein whose presence is considered a prerequisite for cuproptosis, along with decreases in LIAS, an enzyme required for protein lipoylation, DLAT, a key lipoylated component of the pyruvate dehydrogenase complex, ACO2, an iron-sulfur-cluster-dependent enzyme of the TCA cycle, and POLD1, a DNA polymerase subunit that also relies on iron-sulfur clusters.

Perhaps most strikingly, the atretic follicles showed increased oligomerization of DLAT, meaning that multiple copies of this mitochondrial protein had clumped together, which is the hallmark biochemical event of cuproptosis. The diminished lipoylation signals in the same samples reinforced the picture of a mitochondrial metabolic apparatus coming apart under copper stress. Taken together, these observations suggested that copper overload is not merely a passive byproduct of follicular degeneration but may be an active driver of the granulosa cell loss that defines atresia.

To test this idea directly, the team turned to cultured granulosa cells and exposed them to copper sulfate. The treatment produced the expected cascade of damage: copper accumulated inside the cells, mitochondrial function deteriorated, and markers of cuproptosis-associated injury appeared. When the researchers applied ammonium tetrathiomolybdate, a clinical copper chelator, the damage was preferentially attenuated, confirming that the injury was specifically copper-dependent rather than a nonspecific toxic effect. This pharmacological validation is important because it establishes copper overload as a sufficient and specific trigger for the cell death program observed in the cultures.

The pivotal experiments involved spermidine, a polyamine found in foods ranging from wheat germ to aged cheese and long studied for its roles in autophagy, mitochondrial function, and anti-aging biology. When the researchers supplemented the copper-stressed granulosa cells with spermidine, mitochondrial dysfunction was substantially relieved. Conversely, when they depleted polyamines from the cells, the loss of iron-sulfur cluster proteins and lipoylated proteins became worse, indicating that endogenous polyamines provide a baseline level of protection against copper-driven mitochondrial collapse. In mice subjected to copper overload, spermidine supplementation likewise attenuated ovarian injury, extending the protective effect from cell culture to a whole-animal model.

The mechanistic explanation the authors propose centers on a regulatory axis involving a microRNA and its target. Spermidine treatment reduced the abundance of miR-194a-5p, a small regulatory RNA that suppresses the production of DLAT. With miR-194a-5p lowered, DLAT expression recovered, and downstream metabolic functions followed: pyruvate dehydrogenase activity was preserved, ATP production was maintained, and both NDUFS1, a component of mitochondrial respiratory complex I, and ACO2 activity were protected. In other words, spermidine appears to act upstream, releasing the brake that miR-194a-5p places on DLAT, thereby keeping the lipoylated machinery of oxidative metabolism intact and less susceptible to copper-induced aggregation.

This spermidine/miR-194a-5p/DLAT axis provides a coherent narrative linking copper stress to follicular atresia. Excess copper entering granulosa cells through SLC31A1 threatens to aggregate DLAT and destroy iron-sulfur proteins; miR-194a-5p, by suppressing DLAT, may compound the vulnerability; and spermidine intervenes by damping the microRNA and restoring the metabolic scaffold. The work also connects to a broader and rapidly growing literature on cuproptosis, including recent reports that copper-triggered death can arrest meiosis in oocytes, suggesting that copper homeostasis is emerging as a recurring theme in reproductive biology.

The practical implications are worth noting with appropriate caution. For livestock production, where follicular atresia directly limits reproductive efficiency, the study suggests that managing copper exposure and possibly supporting polyamine metabolism could help protect ovarian function. For human reproductive medicine, the pig model’s relevance makes the findings intriguing, though the authors and the field will need to establish whether the same axis operates in human granulosa cells and whether spermidine interventions are safe and effective in that context. What the study firmly establishes is a testable mechanism: a dietary-derived polyamine, a microRNA, and a lipoylated mitochondrial enzyme forming a regulatory circuit that determines whether copper stress becomes lethal. As cuproptosis research moves from cancer biology into physiology and agriculture, this work demonstrates that the copper cell death pathway is not just a laboratory curiosity but a process with real consequences for one of biology’s most economically and personally significant processes, the maintenance of the ovarian follicle reserve.

Subject of Research: Spermidine-mediated protection of ovarian granulosa cells from copper overload-induced cuproptosis via the miR-194a-5p/DLAT axis

Article Title: Spermidine attenuates copper overload-induced cuproptosis in porcine granulosa cells through the miR-194a-5p/DLAT axis

Article References: Wang, X., Jiang, D., Ling, W., Ji, C., Qi, Y., An, X., Li, S., Lu, L., Li, M., & Kang, B. (2026). Spermidine attenuates copper overload-induced cuproptosis in porcine granulosa cells through the miR-194a-5p/DLAT axis. Cell Death Discovery. https://doi.org/10.1038/s41420-026-03379-2

Image Credits: AI Generated

DOI: 10.1038/s41420-026-03379-2

Keywords: cuproptosis, spermidine, copper overload, granulosa cells, DLAT, miR-194a-5p, follicular atresia, mitochondrial dysfunction, SLC31A1, iron-sulfur cluster proteins, ovarian follicle, cell death