Iron chaperones and RNA-binding proteins, PCBP1 and PCBP2, maintain hepatic iron balance and protect against ferroptosis

Poly rC binding proteins (PCBPs) 1 and 2 bind iron and ssDNA/RNA, acting as iron chaperones for enzyme metalation, ferritin storage, and iron toxicity prevention. Previously, we demonstrated that liver-specific PCBP1 deletion in mice increased unchaperoned iron, causing hepatic oxidative damage and steatosis. Little is known about the functions of PCBP2 in vivo. To define the roles of PCBP1 and PCBP2 in murine hepatic iron metabolism, we generated conditional (Alb-Cre) and vector-mediated (AAV8-TBG-iCre) deletion as models of chronic and acute PCBP deficiency, respectively. Conditional deletion in hepatocytes and cholangiocytes caused chronic, severe hepatic injury, with steatosis, necrosis, ductular reaction, increased plasma ALT and ALP, and Nrf2-dependent antioxidant gene activation. Vector-mediated PCBP1/PCBP2 double deletion in adult mice led to acute liver injury with periportal inflammation, apoptosis, and DNA damage, followed by compensatory hepatocyte proliferation. In contrast, single deletions caused mild or no acute liver abnormalities, suggesting a functional redundancy. Loss of both chaperones caused oxidative and ferroptosis-like injury, indicated by increased lipid peroxidation, 8-oxoguanine-modifcations of nucleic acids, and Nrf2 target gene expression. Dietary iron restriction, but not vitamin E, markedly improved liver pathology, normalized plasma markers, and reduced oxidative stress, demonstrating that iron toxicity, not general lipid peroxyl radicals, drives hepatocellular injury. Rescue experiments with PCBP1 variants demonstrated that wild-type PCBP1 restored normal hepatic function, while iron-binding-deficient (ΔFe) and RNA/DNA-binding-deficient (ΔRNA) variants failed. PCBP1ΔFe expression did not prevent liver damage or suppress ALT levels. PCBP1ΔRNA expression was, surprisingly, toxic to hepatocytes and caused more rapid cell death than transduction with no PCBP1 at all, suggesting that unbalanced iron- and RNA/DNA-binding activities are toxic to hepatocytes. These results establish PCBP1 and PCBP2 as essential, cooperative hepatic iron regulators whose loss causes ferroptosis-like injury through dysregulated iron and RNA/DNA homeostasis.