Summary: Researchers unmasked a hidden metabolic mechanism that explains why advanced maternal age (AMA) impairs female fertility and reduces the success rates of assisted reproductive technology (ART). Utilizing non-targeted lipidomics, proteomics, and advanced multi-omic sequencing (RNA-seq, Cut&Tag, and ATAC-seq), the research team discovered that embryos from aged females exhibit a severe decline in autophagy.
This loss of cellular recycling halts the degradation of a key enzyme called ACOX1, sparking an abnormal, hyper-activated state of fatty acid beta-oxidation (beta-FAO). This metabolic overdrive consumes vital pools of oxidized nicotinamide adenine dinucleotide (NAD+), blocking critical histone modifications (H3K9ac erasure) and preventing embryos from successfully exiting minor zygotic genome activation, which ultimately triggers early developmental arrest.
Key Facts
- The Fall of Cellular Recycling: Autophagy is a vital self-cleaning process that cells use to break down damaged proteins and regulate metabolism during early embryo growth. The research coalition proved that this crucial cellular survival mechanism steadily declines as maternal age increases.
- The ACOX1 Metabolic Trap: Using precision molecular assays (RIP-qPCR and RNA pull-down), scientists tracked down the exact enzyme responsible for the damage. In young embryos, the protein LC3B flags and safely degrades an enzyme called ACOX1. When autophagy fails in AMA embryos, ACOX1 levels skyrocket, forcing the cell into an unnatural metabolic state.
- Hyper-Activated Burning: High ACOX1 expression triggers an intense surge in fatty acid beta-oxidation (beta-FAO), meaning the older embryo begins aggressively and abnormally burning through its internal fat stores. While energy production is vital, this uncontrolled metabolic burning creates severe internal imbalances.
- Draining the NAD+ Battery: The abnormally active lipid-burning process requires immense resources, completely draining the embryo’s internal stores of oxidized nicotinamide adenine dinucleotide (NAD+). This severe NAD+ depletion robs the embryo of the primary chemical currency needed to power structural modifications on its DNA.
- The Epigenetic Traffic Jam: Without adequate NAD+, the embryo fails to perform a critical genetic chore: the erasure of a chemical tag on its DNA called H3K9ac. This failure blocks a vital developmental milestone known as the timely exit from minor zygotic genome activation, effectively trapping the embryo’s genes in a primitive state and halting blastocyst formation.
- Chemical Rescue via Rapamycin: To confirm absolute causality, researchers added the autophagy activator Rapamycin directly into the embryo culture medium. The pharmacological treatment successfully restarted the recycling process, lowered ACOX1 expression, balanced lipid metabolism, and significantly improved blastocyst development rates in aged mouse models.
- Evolutionary Clinical Validation: Highlighting immediate relevance for human fertility clinics, the team confirmed that this exact same molecular sequence is identical and highly conserved inside human embryos harvested from women of advanced maternal age, paving the way for targeted metabolic interventions to salvage early embryonic health during IVF cycles.
Source: Science China Press
AMA significantly impairs female fertility and reduces the success of assisted reproductive technology (ART) by compromising early embryonic development. Autophagy, a vital process in embryogenesis, has been shown to decline with increasing maternal age.
This reduction is thought to disrupt key metabolic pathways essential for normal embryonic development. However, the mechanistic link between autophagy-mediated metabolic regulation and the developmental potential of embryos from aged females remains insufficiently understood.
To address this gap, the research team led by Prof. Jingyu Li, Prof. Shimeng Guo, Prof. Guoning Huang at Chongqing Medical University, and Shaorong Gao at Tongji University finds a decreased autophagy in embryos from aged female mice and that supplementation with Rapamycin (an autophagy activator) in the culture medium improved early embryonic development, suggesting that impaired autophagy may be one of the essential reasons for the decline in development of embryos from aged female mice.
The non-targeted lipidomics and proteomics suggest an enhanced fatty acid β-oxidation (β-FAO) in embryos from aged female mice or low-autophagy embryos. With RIP-qPCR and RNA pull-down, the research team reveals that decreased autophagy in low-autophagy embryos hinders LC3B-dependent degradation of Acox1, elevating ACOX1 expression, thereby enhancing β-FAO.
Overexpression of Acox1 reduces blastocyst formation rates, while knockdown of Acox1 partially rescues embryonic development in low-autophagy embryos, suggesting that autophagy-mediated regulation of β-FAO plays a pivotal role in the developmental potential of embryos from aged female mice.
Subsequently, RNA-seq, Cut&Tag, and ATAC-seq analyses suggest that abnormally active β-FAO in low-autophagy embryos excessively consumes oxidized nicotinamide adenine dinucleotide (NAD+), leading to failure in H3K9ac erasure, thereby interfering with the timely exit of minor zygotic genome activation, ultimately causing developmental defects.
Furthermore, this evolutionarily conserved mechanism is confirmed in embryos derived from women with advanced age, indicating the significant clinical relevance of the metabolic intervention targets identified in this study.
Future Prospects
This work investigates the molecular mechanisms underlying autophagy-driven lipid metabolic dysregulation in embryos from aged female mice and humans, and elucidates how these metabolic alterations impair embryonic developmental competence. The findings may offer a potential clinical strategy to mitigate the decline in early embryonic development associated with maternal aging.
Key Questions Answered:
A: Because maternal aging causes a vital cellular self-cleaning process called autophagy to break down. In young embryos, autophagy acts like a precision recycling system that clears out unnecessary enzymes and balances metabolism. When this system fails in older embryos, a specific metabolic enzyme called ACOX1 builds up to dangerous levels. This accumulation forces the embryo to aggressively over-burn its own fats, setting off a catastrophic chain reaction that completely stalls early genetic development.
A: The problem is that hyper-active fat burning acts like a massive drain on the embryo’s internal battery, completely using up a vital coenzyme called NAD+. Early embryos must use NAD+ to erase old chemical tags on their DNA so they can activate next-generation growth genes. When the over-active fat burning drains the NAD+ supply dry, the embryo cannot clear those old tags. This creates an epigenetic traffic jam that locks the genes in a primitive state, causing the embryo to fail before it can form a blastocyst.
A: It opens up an immediate, practical clinical strategy to improve IVF success rates for older women. By proving that adding an autophagy activator like Rapamycin directly into the embryo culture medium can manually restart the cellular cleaning system, lower the harmful ACOX1 enzyme, and successfully rescue embryo development, the study maps out a concrete way to fix older eggs. Because this exact same metabolic defect was verified in human eggs from older women, clinics can now look into safe metabolic additives to protect human blastocyst development.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- Journal paper reviewed in full.
- Additional context added by our staff.
About this neurodevelopment and aging research news
Author: Siyun Qin
Source: Science China Press
Contact: Siyun Qin – Science China Press
Image: The image is credited to Neuroscience News
Original Research: Open access.
“Autophagy-dependent disruption of β-FAO-mediated histone acetylation in embryos during maternal aging” by Dongmei Deng, Chong Li, Ling Zhu, Yin Tian, Jie Wang, Chenshi Li, Mo Chen, Guoning Huang, Shaorong Gao, Shimeng Guo, and Jingyu Li. Science Bulletin
DOI:10.1016/j.scib.2026.02.053
Abstract
Autophagy-dependent disruption of β-FAO-mediated histone acetylation in embryos during maternal aging
Advanced maternal age (AMA) significantly impairs female fertility and reduces the success of assisted reproductive technology (ART) by compromising early embryonic development. Autophagy, a vital process in embryogenesis, has been shown to decline with increasing maternal age.
This reduction is thought to disrupt key metabolic pathways essential for normal embryonic development. However, the mechanistic link between autophagy-mediated metabolic regulation and the developmental potential of embryos from aged females remains insufficiently understood.
To address this gap, this study investigates the molecular mechanisms underlying autophagy-driven lipid metabolic dysregulation in embryos from aged female mice and humans, and elucidates how these metabolic alterations impair embryonic developmental competence.
The findings may offer a potential clinical strategy to mitigate the decline in early embryonic development associated with maternal aging.
