Polystyrene nanoplastics carrying copper ion induce FDX1-mediated cuproptosis

Polystyrene nanoplastics (PS-NPs) and copper ions (Cu²⁺) are common environmental pollutants, yet their combined toxicological effects remain poorly understood. This study demonstrates that PS-NPs act as carriers of Cu²⁺, facilitating intracellular accumulation and inducing cuproptosis, a recently identified form of regulated cell death. Using zebrafish larvae and Hep G2 cells, we showed that co-exposure to PS-NPs and Cu²⁺ disrupted copper homeostasis, promoted DLAT oligomerization, impaired mitochondrial structure and function, and activated the cuproptosis pathway. Molecular docking revealed stable binding of PS-NPs and Cu²⁺ to the key regulator FDX1, further aggravating cuproptosis. FDX1 overexpression experiments confirmed its pivotal role, as enhanced expression significantly increased DLAT aggregation and cell death. This study is the first to reveal the molecular mechanism by which PS-NPs mediate FDX1-dependent cuproptosis via a "Trojan horse" effect. These findings provide novel insights into the mechanisms of nanoplastics-heavy metal co-exposure and offer a potential molecular target for mitigating environmental toxicity.