Credit:Identification of hyperoxidized PRDX3 as a ferroptosis marker reveals ferroptotic damage in chronic liver diseases.

Ferroptosis is a novel form of cell death characterized by the accumulation of phospholipid hydroperoxides catalyzed by intracellular iron. Its activation is often marked by an increase in intracellular iron ion concentration and an imbalance in the antioxidant system, leading to lipid peroxide accumulation and cell death. Oxidative stress and dysregulated iron metabolism are particularly prevalent in alcoholic and non-alcoholic fatty liver diseases, suggesting that ferroptosis may play a critical role in these conditions. However, identifying ferroptosis under physiological conditions is challenging due to the lack of specific biomarkers. Although studies have shown that transferrin receptor 1 (TfR1) increases during ferroptosis, this marker is also present on cell surfaces under normal conditions and is regulated by various factors, thus lacking sufficient specificity. Consequently, there is a need for a more sensitive and specific biomarker to accurately detect ferroptotic cells. Cui's research team aims to develop a sensitive and specific detection method for ferroptosis by identifying proteins that undergo specific changes during the process.

The researchers initially selected various cell lines (e.g., SV589, HT1080, A549, Huh7, HT29) for experiments and treated them with different concentrations of ferroptosis inducers to detect the generation of hyperoxidized PRDX3. Immunoblotting analysis demonstrated that PRDX3 undergoes hyperoxidation under ferroptotic conditions, which is both specific and concentration-dependent. Immunofluorescence microscopy analysis indicated that during ferroptosis, the subcellular localization of PRDX3 significantly changes, shifting from the mitochondria to the plasma membrane, further supporting the critical role of PRDX3 in the ferroptosis process.

Subsequently, the researchers established mouse models for alcoholic fatty liver disease (AFLD) and non-alcoholic fatty liver disease (NAFLD). Through immunoblotting and immunofluorescence analyses, they detected hyperoxidized PRDX3 expression in the livers of both groups of mice. The results demonstrated that alcoholic liver injury is closely associated with ferroptosis, with hyperoxidized PRDX3 serving as an effective marker of ferroptosis in the AFLD model. Similarly, non-alcoholic liver injury was found to be related to ferroptosis, with hyperoxidized PRDX3 proving effective in the NAFLD model as well. The positive correlation between elevated levels of AST and ALT and the expression of hyperoxidized PRDX3 further confirmed the ferroptosis mechanism in liver injury.

Additionally, the study showed that PRDX3-knockout SV589 and HT1080 cells exhibited significant resistance to erastin-induced ferroptosis, while cells with restored PRDX3 expression regained sensitivity to ferroptosis. This indicates that PRDX3 is essential in the ferroptosis process, with its hyperoxidized form playing a crucial role. Furthermore, cystine uptake and glutamate export experiments revealed that hyperoxidized PRDX3 promotes ferroptosis by inhibiting cystine uptake without affecting glutamate export, highlighting its specific mechanistic role in the ferroptosis process.

In summary, the research team demonstrated the application of hyperoxidized PRDX3 as a specific marker for ferroptosis in both in vitro and in vivo models, revealing the critical role of ferroptosis in alcoholic and non-alcoholic fatty liver diseases. Hyperoxidized PRDX3 exhibits high specificity and sensitivity, addressing the issue of marker specificity that previous methods lacked. Both in vivo and in vitro experiments confirmed its reproducibility and reliability under physiological and pathological conditions. These findings provide a new tool for studying the role of ferroptosis in other diseases and lay a theoretical foundation for developing new therapeutic strategies.

Although the study underscored the significant role of ferroptosis in alcoholic and non-alcoholic fatty liver diseases, there are still shortcomings in clinical validation, marker specificity, experimental scope, and mechanistic research. Questions remain regarding whether ferroptosis can serve as an early diagnostic marker for these diseases or as an effective therapeutic target. These gaps and challenges need to be addressed through further research to ensure the applicability and reliability of the findings in broader biological and clinical contexts. Future research should focus on expanding validation ranges, optimizing detection methods, delving deeper into mechanisms, and fostering interdisciplinary collaboration to enhance the scientific value and clinical potential of ferroptosis research comprehensively. While promising, the significance of ferroptosis in other clinical diseases still requires verification.

Reference:

Cui, Shaojie, et al. "Identification of hyperoxidized PRDX3 as a ferroptosis marker reveals ferroptotic damage in chronic liver diseases." Molecular cell 83.21 (2023): 3931-3939.