Yu Li,Min Yu,Junping Ren,Tianming Qiu,Jingyuan Zhang,Chenbing Wu,Jie Bai,Xiance Sun,Xiaofeng Yao
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.
Zhang Qian,Ding Haoxuan,Yu Xiaonan,Wang Qiwen,Li Xuejiao,Zhang Ruiqiang,Feng Jie
Iron overload often occurs during blood transfusion and iron supplementation, resulting in the presence of non-transferrin-bound iron (NTBI) in host plasma and damage to multiple organs, but effects on the intestine have rarely been reported. In this study, an iron overload mouse model with plasma NTBI was established by intraperitoneal injection of iron dextran. We found that plasma NTBI damaged intestinal morphology, caused intestinal oxidative stress injury and reactive oxygen species (ROS) accumulation, and induced intestinal epithelial cell apoptosis. In addition, plasma NTBI increased the relative abundance of Ileibacterium and Desulfovibrio in the cecum, while the relative abundance of Faecalibaculum and Romboutsia was reduced. Ileibacterium may be a potential microbial biomarker of plasma NTBI. Based on the function prediction analysis, plasma NTBI led to the weakening of intestinal microbiota function, significantly reducing the function of the extracellular structure. Further investigation into the mechanism of injury showed that iron absorption in the small intestine significantly increased in the iron group. Caco-2 cell monolayers were used as a model of the intestinal epithelium to study the mechanism of iron transport. By adding ferric ammonium citrate (FAC, plasma NTBI in physiological form) to the basolateral side, the apparent permeability coefficient ( Papp ) values from the basolateral to the apical side were greater than 3×10 −6 cm s −1 . Intracellular ferritin level and apical iron concentration significantly increased, and SLC39A8 (ZIP8) and SLC39A14 (ZIP14) were highly expressed in the FAC group. Short hairpin RNA (shRNA) was used to knock down ZIP8 and ZIP14 in Caco-2 cells. Transfection with ZIP14-specific shRNA decreased intracellular ferritin level and inhibited iron uptake. These results revealed that plasma NTBI may cause intestinal injury and intestinal flora dysbiosis due to the uptake of plasma NTBI from the basolateral side into the small intestine, which is probably mediated by ZIP14.
危险品化学品经营许可证（带存储）