Autophagy is involved in the protective effect of endophilin A2 on H2O2-induced apoptosis in H9C2 cardiomyocytes

Apoptosis plays a critical role in normal embryonic development and tissue homeostasis regulation. EndophilinA2 (EndoA2) is widely reported to regulate endocytosis. Additionally, EndoA2 has been demonstrated to be involved in tumor metastasis, neuroregulation and vascular function. In this study, we used siRNA and Ad-EndoA2 transfection strategy to investigate whether EndoA2 provides a protective effect against apoptosis induced by H2O2 in H9C2 cardiomyocytes and the underlying mechanisms. We found that EndoA2 siRNA knockdown promoted H2O2-induced apoptosis in H9C2 cardiomyocytes, evidenced by decreased cell number, increased apoptotic cells, and activation of caspase-3. In contrast, EndoA2 overexpression showed the opposite effects and inhibited H2O2-induced apoptosis in H9C2 cardiomyocytes. Further studies revealed that EndoA2 overexpression strengthened autophagy, evidenced by the increased LC3 II/I ratio and P62 degradation, whereas EndoA2 siRNA knockdown produced the opposite effects. Furthermore, we revealed that there was an interaction between Bif-1 and Beclin-1. Upon H2O2 treatment, the association of Bif-1 and Beclin-1 remarkably increased. EndoA2 overexpression further promoted the binding of Bif-1 with Beclin-1, whereas EndoA2 siRNA knockdown reduced this association. These data strongly suggested that EndoA2 inhibited H2O2-induced apoptosis in H9C2 cardiomyocytes, possibly by promoting Bif-1 to form a complex with Beclin-1 and strengthening autophagy. This study provides a novel target for heart diseases.