Mechanisms and targeted intervention of mitochondria-dependent ferroptosis and abnormal ductular reaction caused by...

Chronic hepatobiliary diseases (CHDs), the second leading disease burden worldwide, are closely related to the occurrence and development of abnormal ductular reaction (DR). Tobacco smoking is an important pathogenic risk factor for CHDs, however, the functions and molecular mechanisms underlying in the tobacco smoking-induced abnormal DR, remain largely uninvestigated. Benzo[a]pyrene (B[a]P) is a representative hepatobiliary toxic substance among tobacco carcinogens. Our present study revealed that, B[a]P drove the DR occurrence through inducing the ferroptosis in bile duct epithelial cells (BECs). For the molecular mechanisms, the metabolic activation product of B[a]P, benzo[a]pyrene diol epoxide (BPDE) could directly bind to the Lys123 site of 14-3-3ε protein, which in turn inhibited its ubiquitination degradation. The abnormally elevated 14-3-3ε in turn activated voltage dependent anion channel 1 (VDAC1) through phosphoserine binding/regulation, leading to an abnormal coupling between endoplasmic reticulum (ER) and mitochondria. The shortened distance between the ER and mitochondria caused the mitochondrial Ca²⁺ overload, inducing the overproduction of reactive oxygen species (ROS). These processes ultimately caused the ferroptosis in BECs and initiated the DR progression. In terms of targeted intervention, we further innovatively screened and identified a small molecule of traditional Chinese medicine monomer, quercetin, which could efficiently target the phosphoserine binding region of 14-3-3ε protein. Finally, we confirmed that targeted intervention of 14-3-3ε by quercetin significantly inhibited the B[a]P-induced ferroptosis and abnormal DR.