Transcription factor AP-2α triggers apoptosis in cardiac myocytes

Idiopathic-dilated cardiomyopathy (IDC) is a common primary myocardial disease of unknown etiology associated with apoptosis, cardiac dilatation, progressive heart failure and increased mortality. An elevation of the transcription factor activator protein 2α (AP-2α) is involved in vertebrate embryonic development and oncogenesis. Here, we show that AP-2α protein is expressed in the human heart and increased in human failing myocardium with IDC. Adenovirus-mediated overexpression of human AP-2α triggered apoptosis and increased mRNA levels of Bcl-2 family members Bax and Bcl-x in rat cardiomyocytes. Immunohistological analysis of human myocardium revealed an increased percentage of AP-2α-positive nuclei in IDC and, interestingly, a colocalization of AP-2α-positive but not -negative cells with a caspase-cleaved fragment of poly(ADP-ribose)polymerase. We suggest AP-2α as a novel cardiac regulator implicated in the activation of apoptosis in IDC.