Affixin (β-parvin) promotes cardioprotective signaling via STAT3 activation

Abstract

The focal adhesion protein affixin (β-parvin) is highly expressed in the heart and is associated with the sarcomeric z-disc as well as the cell membrane. While affixin is known to be involved in cell adhesion and migration, its functional role in cardiomyocytes remains unclear. To gain insight into the function of affixin, we performed a yeast-two-hybrid-screen employing affixin as a bait. The signal transducer and activator of transcription 3 (STAT3) was detected as a binding partner of affixin. Overexpression of affixin in neonatal rat cardiomyocytes resulted in markedly enhanced STAT3 DNA binding activity and upregulation of STAT3-dependent genes. Moreover, upregulation of affixin led to cardiomyocyte hypertrophy with an increase in cell size and enhanced protein synthesis. Consistent with STAT3 activation, overexpression of affixin also protected cardiomyocytes from doxorubicin-induced apoptosis. Finally, HUVECs that were cultivated in medium from affixin-overexpressing cardiomyocytes responded with an increase in tubuli formation, in line with a proangiogenic effect of affixin. In conclusion, we demonstrate that affixin activates STAT3 in cardiomyocytes and promotes characteristic STAT3-related effects such as hypertrophy, protection against apoptosis, and angiogenesis. This novel pathway might therefore represent a target for cardioprotective strategies.