Neurotoxicity of Realgar: Crosstalk Between UBXD8-DRP1-Regulated Mitochondrial Fission and PINK1-Parkin-Mediated Mitophagy

Realgar is a toxic mineral medicine containing arsenic that is present in many traditional Chinese medicines. It has been reported that the abuse of drugs containing realgar has potential neurotoxicity, but its mechanism of toxicity has not been fully clarified. In this study, we demonstrated that arsenic in realgar promoted mitochondrial fission via UBXD8-mediated DRP1 translocation to the mitochondria and activated mitophagy via PINK1-Parkin, resulting in mitochondrial dysfunction and nerve cell death in the rat cortex. We used PC12 cells and treated them with inorganic arsenic (iAs). Mdivi-1, a mitochondrial fission inhibitor, and the siRNA UBXD8 or PINK1 were used as interventions to verify the precise mechanism by which arsenic affects realgar-induced mitochondrial instability. The results revealed that the arsenic in realgar accumulated in the brain and led to neurobehavioral abnormalities in the rats. We demonstrated that arsenic in realgar-induced high expression of UBXD8 promoted the translocation of DRP1 to the mitochondria, where it underwent phosphorylation, which led to the over-fission of the mitochondria and mitochondria-mediated apoptosis. Moreover, the over-fission of the mitochondria activates mitophagy, which is self-protective but only partially alleviates apoptosis and mitochondria dysfunction. Our findings revealed the crosstalk between mitochondrial fission and mitophagy in realgar-induced neurotoxicity. These results highlight the role of the transposition of DRP1 by UBXD8 in realgar-induced mitochondrial dysfunction and provide new ideas and data for the study of the mechanism of realgar-induced neurotoxicity.