Abstract
Vinexin-β is one of the adaptor proteins that are primarily involved in signal transduction and cytoskeletal organization under various pathological conditions, including cardiac hypertrophy. However, the role of Vinexin-β in myocardial infarction (MI) remains unknown. In this study, dramatically up-regulated Vinexin-β expression was observed in both ischaemic human hearts and infarcted animal hearts. To explore the potential involvement of Vinexin-β in MI further, we induced MI injury in global Vinexin-β-knockout mice and wild-type (WT) controls as well as in mice with cardiac-specific over-expression of the human Vinexin-β gene-transgenic (TG) and -non-transgenic (NTG) littermates. Compared with that observed in WT controls, Vinexin-β deficiency significantly decreased MI-induced infarct size, concomitant with an improved cardiac function, leading to an increase in the survival rate. The myocardial apoptosis in the border zone was dramatically reduced by Vinexin-β deficiency, resulting from the altered expression of apoptotic factors. Furthermore, Vinexin-β depletion mitigated the inflammatory response, as evidenced by reduced inflammatory cell infiltration, decreased expression of cytokines and the inactivation of NF-κB (nuclear factor κB) signalling. In contrast, Vinexin-β-TG mice were much more susceptible to MI injury compared with NTG controls. Further mechanism analyses suggested that Vinexin-β exerted detrimental effects largely dependent on blocking AKT signalling. The effects and mechanisms of Vinexin-β on MI observed in vivo were further confirmed by our in vitro assays. When collected, these data demonstrate for the first time that Vinexin-β increases MI-induced mortality and worsens cardiac dysfunction through aggravation of myocardial apoptosis and inflammatory response.