Cigarette smoke induces mitochondrial dysfunction via PKCd-p66Shc signaling pathway in human bronchial epithelial cells

Background: Airway epithelial mitochondrial dysfunction plays an important role in the pathogenesis of chronic obstructive pulmonary disease (COPD). The p66Shc adaptor protein is a newly recognized mediator of mitochondrial dysfunction. However, it is little known about the effect of p66Shc on airway epithelial mitochondrial injury induced by cigarette smoke extract (CSE). Objectives: The present study was designed to investigate the roles of p66Shc and its upstream regulator PKCδ in the mitochondrial injury of airway epithelial cells induced by CSE. Methods: Airway epithelial cells (Beas-2b) were exposed to CSE, and the cells were further stimulated with 7.5% CSE after the knockdown of p66Shc or 30-min pretreatment with PKCδ inhibitor rottlerin. Then the degree of cell injury and mitochondrial function were studied. The expression of p66Shc and PKCδ were determined by western-blot. Results: Our present study revealed that CSE increased p66Shc expression and its mitochondrial translocation in concentration and time dependent manners in airway epithelial cells. And p66Shc siRNA significantly attenuated mitochondria dysfunction and cell injury when Beas-2b cells were stimulated with 7.5% CSE. The total and phosphorylated expression of PKCδ were significantly increased associated with mitochondrial dysfunction and cell injury when airway epithelial cells were exposed to 7.5% CSE. The pretreatment with rottlerin could notably suppress CSE-induced p66Shc phosphorylation and its mitochondrial translocation and protect mitochondria and cells against oxidative damage. Conclusions: These data suggest that PKCδ-p66Shc pathway may be involved in the pathogenesis of COPD.