Advanced glycation end products induce mitochondrial pathway apoptosis in glomerular mesangial cells

Abstract

Objective To investigate whether advanced glycation end products (AGEs) can induce the expression of Ros, JC-1 and its apoptosis-related proteins in glomerular mesangial cells under high glucose environment, induce apoptosis and injury of glomerular mesangial cells. Methods Rat glomerular mesangial cell line HBZY-1 was cultured in vitro. The cells were cultured with different concentrations of AGEs for 0, 12, 24 and 48 hours respectively. MTT assay was used to observe the cell proliferation ability. After the optimal time and concentration of AGEs were selected, the caspase enzyme inhibitor Z-VAD-fmk and reactive oxygen species (ROS) scavenger N-acetyl-L-cysteine (NAC) were cultured and the apoptosis rate was detected by cell death detection apoptosis ELISA plus and Annexin V-FITC/PI kit. JC-1 staining was used to detect the changes of mitochondrial membrane potential (MMP). Cell ROX deep red flow cytometry was used to detect the total ROS level. The expression of anti-apoptotic protein Bcl-2, pro-apoptotic protein BAX, caspase-9, caspase-3 and poly ADP-ribose polymerase (PARP)-activated fragments was detected by Western blotting. Results AGEs could decrease the activity of glomerular mesangial cells in a time and concentration-dependent manner, and induce cell death. The percentage of apoptotic cells in glomerular mesangial cells was significantly increased after treatment with 250 mg/L AGEs for 24 h (P<0.01), and Z-VAD-fmk could significantly alleviate AGEs-induced glomerular mesangial cell apoptosis (P<0.01). Compared with the control group, AGEs increased the level of intracellular reactive oxygen species and decreased MMP in a time-dependent manner, and the two time points that AGEs significantly caused the change were 1 h and 2 h (all P<0.01). AGEs also reduced the expression of antiapoptotic protein Bcl-2 and increased the expression of pro-apoptotic protein Bax, cleaved caspase-9, cleaved caspase-3 and cleaved PARP (all P<0.01). Compared with AGEs group, NAC could significantly stabilize MMP (P<0.01), increase Bcl-2 expression (P<0.01), and decrease the expression of BAX, cleaved caspase-9, cleaved caspase-3 and cleaved PARP (all P<0.01). Conclusion AGEs induce mitochondrial pathway apoptosis in glomerular mesangial cells by increasing intracellular ROS level and destroying MMP. Key words: Mesangial cells; Apoptosis; Reactive oxygen species; Advanced glycation end products; Mitochondrial pathway