McFerritin cooperates with McNrf2 to attenuate benzo[a]pyrene-induced oxidative stress in the thick-shell mussel...

Benzo[a]pyrene (B[a]P), a pervasive polycyclic aromatic hydrocarbon (PAH), induces oxidative stress and cellular damage in marine organisms, posing significant ecological risks. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a key regulator of antioxidant defenses, yet its interaction with ferritin-a critical iron storage protein-remains poorly understood in mollusks. Here, we identified a novel ferritin homolog, McFerritin, in the thick-shelled mussel Mytilus coruscus and investigated its role in B[a]P-induced oxidative stress. Quantitative PCR revealed that McFerritin expression in the adductor muscle was 4.37-fold higher than in the gills, with 5.58 to 9.11-fold upregulation observed in the digestive glands and mantles post-B[a]P exposure. GST pull-down assays confirmed the direct interaction of McFerritin with McNrf2. RNAi experiments demonstrated reciprocal regulation: knockdown of McFerritin increased McNrf2 expression by 1.55-fold and 1.70-fold, while silencing McNrf2 elevated McFerritin levels by 1.30-fold and 1.34-fold in DMSO-treated samples. Silencing either gene resulted in increased apoptosis rates (5.1 % and 13.2 %), enhanced reactive oxygen species (ROS) accumulation (1.26- and 1.79-fold), and decreased activities of antioxidant enzymes (T-AOC, SOD, CAT), underscoring their synergistic role in oxidative stress mitigation. This study elucidates the protective role of Ferritin in M. coruscus, confirming the interaction between McFerritin and McNrf2 in mediating defense mechanisms against oxidative stress, thereby advancing understanding of oxidative stress regulation in marine invertebrates and emphasizing their potential as biomarkers for assessing PAH toxicity in coastal ecosystems.