Caveolin-1 Expression Is Required for the Development of Pulmonary Emphysema through Activation of the ATM-p53-p21 Pathway

Free radicals play a role in aging and age-related human diseases, including pulmonary emphysema. Cigarette smoke represents a source of oxidants and is considered an environmental hazard that causes pulmonary emphysema. Here, we show that caveolin-1 activates ataxia telangiectasia-mutated (ATM) after oxidative stress by sequestering the ATM inhibitor, the catalytic subunit of protein phosphatase 2A, into caveolar membranes. We demonstrate that cigarette smoke extracts promote stress-induced premature senescence in wild type but not caveolin-1 null lung fibroblasts and that caveolin-1 expression is required for activation of the ATM-p53-p21(Waf1/Cip1) pathway following stimulation with cigarette smoke extracts in vitro. In vivo studies show that caveolin-1 expression is necessary for cigarette smoking-induced senescence of lung fibroblasts and pulmonary emphysema. These findings bring new insights into the molecular mechanism underlying free radical activation of the ATM-p53 pathway and indicate that caveolin-1 is a novel therapeutic target for the treatment and/or prevention of pulmonary emphysema.