bFGF regulates autophagy and ubiquitinated protein accumulation induced by myocardial ischemia/reperfusion via the activation of the PI3K/Akt/mTOR pathway

Autophagy is involved in the development and/or progression of many diseases, including myocardial ischemia/reperfusion (I/R). In this study, we hypothesized a protective role of basic fibroblast growth factor (bFGF) both in vivo and in vitro and demonstrated that excessive autophagy and ubiquitinated protein accumulation is involved in the myocardial I/R model. Our results showed that bFGF improved heart function recovery and increased the survival of cardiomyocytes in myocardial I/R model. The protective effect of bFGF is related to the inhibition of LC3II levels. Additionally, bFGF enhances the clearance of Ub by p62 and increases the survival of H9C2 cells. Moreover, silencing of p62 partially blocks the clearance of Ub and abolishes the anti-apoptosis effect of bFGF. An shRNA against the autophagic machinery Atg7 increased the survival of H9C2 cells co-treated with bFGF and rapamycin. bFGF activates the downstream signaling of the PI3K/Akt/mTOR pathway. These results indicate that the role of bFGF in myocardial I/R recovery is related to the inhibition of excessive autophagy and increased ubiquitinated protein clearance via the activation of PI3K/Akt/mTOR signaling. Overall, our study suggests a new direction for bFGF drug development for heart disease and identifies protein signaling pathways involved in bFGF action.