ZIP14-VDAC2 mediates the transport of extracellular iron into mitochondria in hepatocytes under PFOS exposure

Perfluorooctane sulfonate (PFOS), classified as a persistent organic pollutant, promotes mitochondrial iron overload through voltage-dependent anion channel 2 (VDAC2). However, the source of iron transported through VDAC2 remains unclear. Here, we reported that PFOS enhanced extracellular iron influx into human hepatocytes HepG2, which peaked at 6 h. Under PFOS exposure, total VDAC2 protein levels remained unchanged, whereas its expression increased in mitochondrial lysates but decreased in cytoplasmic lysates, which were observed both in HepG2 cells and mice liver. Meanwhile, the total protein expression of the extracellular iron importer ZRT/IRT-like protein 14 (ZIP14) was upregulated, whereas absent from the mitochondrial lysates. Knockdown of either VDAC2 or ZIP14 inhibited PFOS-induced extracellular iron influx and mitochondrial iron overload, but did not affect cytoplasmic iron levels. Notably, immunofluorescence colocalization analysis revealed that the timeline of mitochondrial redistribution toward the plasma membrane closely paralleled the course of increased extracellular iron influx. Furthermore, the result of molecular docking suggested the potential interaction between VDAC2 and ZIP14. Together, these works pointed out and further advanced our understanding of the extracellular iron transport into mitochondria in hepatocytes under PFOS exposure and revealed a potential therapeutic target for mitigating the disease mediated by iron-related mechanism.