Beneficial effects of Huaiqihuang on hyperglycemia-induced MPC5 podocyte dysfunction through the suppression of mitochondrial dysfunction and endoplasmic reticulum stress.

ABSTRACT

The present study was performed to investigate the effect of Huaiqihuang (HQH) on hyperglycemia (HG)-induced mitochondrial dysfunction and endoplasmic reticulum (ER) stress in MPC5 podocytes. The effects of HQH and HG on cell viability were assessed using an MTT assay. mRNA and protein expression levels were evaluated using reverse transcription-quantitative polymerase chain reaction and western blot analysis, respectively. Cell apoptosis was assessed using terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling, whereas reactive oxygen species production and alterations in mitochondrial membrane potential were assessed using flow cytometry. DNA damage was evaluated using a comet assay. The results demonstrated that treatment of podocytes with HQH markedly suppressed the HG­induced generation of reactive oxygen species. HQH also significantly improved mitochondrial membrane potential in podocytes exposed to HG. When the podocytes were treated with HG, Ca2+ levels were significantly increased, compared with those in the control group, whereas treatment of the podocytes with HQH significantly reversed the HG­induced upregulation of Ca2+ secretion. Treatment of the podocytes with HQH significantly reversed the HG­induced upregulation of glucose­related protein 78 (GRP78) and C/EBP­homologous protein, which were used as indicators of ER stress. Furthermore, GRP78 loss­of­function attenuated HG­induced podocyte dysfunction, including cell apoptosis and DNA damage. In conclusion, beneficial effects of HQH on HG­induced MPC5 podocyte dysfunction were observed, and occurred through the suppression of mitochondrial dysfunction and ER stress.