Mechanism Of Mitophagy Induced By Mitochondria Damage In DF-1 Cells Exposed To Chromium(?)

Chromium,a common heavy metal pollutant with strong oxidizing property,exists widely in nature.Trivalent chromium(Cr(?))is widely used in animal husbandry,while hexavalent chromium(Cr(?))is mainly used in industrial production.Organism can be exposed to Chromium by means of various approaches,and prolonged Cr(?)exposure can lead to cell damage.it has been reported that Chromium(?)causes mitochondrial dysfunction after absorbed by cells.It is unclear whether Chromium(?)induce the selective autophagic degradation of mitochondria,a biological process called mitophagy.Mitophagy not only recycles intracellular damaged mitochondria to compensate for nutrient deprivation but maintains mitochondria quality control.According to the physical and chemical properties of Cr(?)and the biological functions of mitochondria,it is speculated that Cr(?)may cause mitochondrial damage and then trigger mitophagy.Therefore,this study aims to explore the effect of Chromium(?)on mitophagy in DF-1 cells,carbonyl cyanide m-chlorophenylhydrazone(CCCP),a mitochondrial-uncoupling reagent,which has been shown to induce mitophagy was used in this work.DF-1 cells were incubated with different doses(10?M ? 20?M ? 40?M)of Chromium(?)under variant duration(6h?12h?24h).Notably,the change of autophagy related protein LC3-II and p62 levels were most dramatic after 6 hours of Chromium(?)treatment,but recovered within 24 h.The mitochondrial membrane potential(MMP)as indicators of mitochondrial damage was detected by flow cytometry(FCM).In the present study,we found that Chromium(?)treatment with variant duration induced both mitochondrial mass decrease and mitochondrial depolarization.Furthermore,the expression of TOMM20,a mitochondrial outer membrane protein,was decreased significantly in the presence of Chromium(?).Here,we show that Chromium(?)may contribute to the mitochondrial morphology and function damage,eventually leading to autophagic clearance of mitochondria.Through the above studies,we concluded that Cr(?)entering the cells can cause significant mitochondrial damage and significantly increase the autophagy indicators,and there is a significant dependence between Cr(?)treatment concentration.In addition,we elucidate the time of autophagy peak after Cr(?)treatment by monitoring the dynamic changes of autophagy proteins.The completion of this experiment provides a theoretical basis for further study of the toxicological effects of Cr(?).It contributes to the development of antioxidant drugs against Cr(?)cytotoxicity by autophagy.