Drp1 Aggravates Copper Nanoparticle-Induced ER-Phagy by Disturbing Mitochondria-Associated Membranes in Chicken Hepatocytes

As an efficient alternative copper (Cu) source, copper nanoparticles (nano-Cu) have been widely supplemented into animal-producing food. Therefore, it is necessary to assess the effect of nano-Cu exposure on the biological health risk. Recently, the toxic effects of nano-Cu have been confirmed but the underlying mechanism remains unclear. This study reveals the impact of nano-Cu on endoplasmic reticulum autophagy (ER-phagy) in chicken hepatocytes and further identifies Drp1 and its downstream gene FAM134B as crucial regulators of nano-Cu-induced hepatotoxicity. Nano-Cu exposure can induce Cu ion overaccumulation and pathological injury in the liver, trigger excessive mitochondrial fission and mitochondria-associated membrane (MAM) integrity damage, and activate ER-phagy in vivo and in vitro. Interestingly, the knockdown of Drp1 markedly decreases the expression of FAM134B induced by nano-Cu. Furthermore, the expression levels of ATL3, CCPG1, SEC62, TEX264, and LC3II/LC3I induced by nano-Cu exposure are decreased by inhibiting the expression of Drp1. Simultaneously, the inhibition of FAM134B effectively alleviates nano-Cu-induced ER-phagy by downregulating the expression of ATL3, CCPG1, SEC62, TEX264, and LC3II/LC3I. Overall, these results suggest that Drp1-mediated impairment of MAM integrity leads to ER-phagy as a novel molecular mechanism involved in the regulation of nano-Cu-induced hepatotoxicity. These findings provide new ideas for future research on the mechanism of nano-Cu-induced hepatotoxicity.