[The mechanism of the effect of GalNAc-T4 on the mitochondrial autophagy of the injury of H9c2 cardiomyocytes induced by hypoxia/reoxygenation under high glucose environment via extracellular signal regulated kinase 1/2 signaling pathway].

Objective To investigate the effect of N-acetylglucosamine transferase 4 (GalNAc-T4) on the mitochondrial autophagy in H9c2 cell injury model induced by hypoxia/reoxygenation (H/R) in high glucose (HG) environment, and its regulatory mechanism on extracellular signal regulated kinase 1/2 (ERK1/2) signaling pathway. Methods The cell experiments were divided into five groups. Control group (Control): Cells were transfected with pc-NC cells. HG group: 50 mmol/L glucose was added to the culture medium, and cells were transfected with pc-NC. HG+H/R group: In addition to the HG treatment, cells were subjected to a low oxygen environment for 6 hours, followed by transfection with the pc-NC vector. Overexpression group (pc): Cells were transfected with the pc while undergoing HG+H/R treatment. ERK1/2 agonist epidermal growth factor (EGF) group: Cells were treated with HG+H/R and transfected with the pc, supplemented with 20 ng/mL EGF in the culture medium. The proliferation activity, apoptosis rate, mitochondrial membrane potential, the levels of reactive oxygen species (ROS), iron ions, and mitochondrial autophagy in each group of cells were detected. The expressions of GalNAc-T4, ERK1/2, phosphorylated ERK1/2 (p-ERK1/2), translocase of outer mitochondrial membrane 20 (TOM20), translocase of inner mitochondrial membrane 23 (TIM23), B cell lymphoma 2 (Bcl2), and Bcl2 associated X protein (BAX) were detected in cells. Results Overexpression of GalNAc-T4 significantly increased the proliferation activity, the mitochondrial membrane potential, and the expression of TOM20, TIM23, and Bcl2 in H9c2 cells in HG+H/R group, and decreased the cell apoptosis rate, the levels of ROS and iron ion. Meanwhile, it inhibited the mitochondrial autophagy and downregulated the expression of p-ERK1/2/ERK1/2 and BAX in cells. EGF partially reversed the protective effect of the overexpression of GalNAc-T4 on cardiomyocytes, and the differences were statistically significant. Conclusion Overexpression of GalNAc-T4 could significantly improve the mitochondrial dysfunction in H9c2 cells undergoing hypoxia/reoxygenation under high glucose conditions, inhibit oxidative stress and excessive mitochondrial autophagy, and reduce the apoptosis rate of cardiomyocytes. This may be related to its ability to block the activation of ERK1/2 signaling pathway.