Naringin protects H9C2 cardiomyocytes from chemical hypoxia‑induced injury by promoting the autophagic flux via the activation of the HIF‑1α/BNIP3 signaling pathway
Shanghai Li, Jiamei Jiang, Junyu Fang, Xingyue Li, Chunyan Huang, Weijun Liang, Keng Wu
Abstract
Naringin, a natural bioflavonoid, has been shown to exert protective effects in multiple cardiovascular diseases; however, the protective effects of naringin against hypoxic/ischemia‑induced myocardial are not yet fully understood. Autophagy is a vital factor involved in the pathogenesis of myocardial injury. The aim of the present study was to investigate the protective effects of naringin on H9c2 cells against chemical hypoxia [cobalt chloride (CoCl<sub>2</sub>)]‑induced injury. The role of autophagy and the hypoxia‑inducible factor‑1α (HIF‑1α)/Bcl‑2/BCL2 interacting protein 3 (BNIP3) signaling pathway in the protective effects of naringin were also assessed. The results revealed that naringin pre‑treatment significantly attenuated the CoCl<sub>2</sub>‑induced cytotoxicity and apoptosis, and also decreased caspase‑3 activity, which had been increased by CoCl<sub>2</sub>. In addition, CoCl<sub>2</sub> increased Beclin‑1 expression, enhanced the IL3B‑II/IL3B‑I ratio and increased p62 expression in the H9C2 cells. Treatment with 3‑methyladenine (3‑MA), a selective inhibitor of autophagy, also blocked CoCl<sub>2</sub>‑induced cytotoxicity and apoptosis. Notably, treatment with bafilomycin A1 (Baf A1), an inhibitor of the vacuolar H+ ATPase of lysosomes, resulted in an increase in the upregulation of the LC3B‑II/LC3B‑I ratio, but did not further increase the LC3B‑II/LC3B‑I ratio compared with CoCl<sub>2</sub> treatment. These results suggested that CoCl<sub>2</sub> inhibited the autophagic flux, which resulted in myocardial cell damage. Furthermore, naringin pre‑treatment exacerbated Beclin 1 expression and the increased IL3B‑II/IL3B‑I ratio, and reduced p62 expression in CoCl<sub>2</sub>‑treated H9C2 cells. 3‑MA and Baf A1 both reversed the protective effects of naringin against CoCl<sub>2</sub>‑induced injury, indicating that naringin attenuated CoCl<sub>2</sub>‑induced myocardial cell injury by the increasing autophagic flux. Moreover, naringin treatment resulted in upregulated expression levels of HIF‑1α and BNIP3 in the CoCl<sub>2</sub>‑treated H9C2 cells. The inhibition of the HIF‑1α/BNIP3 signaling pathway using 3‑(5'‑hydroxymethyl‑2'‑furyl)‑1‑benzylindazole (an inhibitor of HIF‑1α) prevented the effects of naringin on the autophagic flux and reversed its protective effects against CoCl<sub>2</sub>‑induced injury. Taken together, these results suggest that naringin protects the H9C2 cells against CoCl<sub>2</sub>‑induced injury by enhancing the autophagic flux via the activation of the HIF‑1α/BNIP3 signaling pathway.