Purpose: Diabetic nephropathy (DN) is one of the most serious complications of diabetes mellitus and one of the most important causes of end-stage renal disease, but its pathogenesis has not been elucidated so far, and there is no effective treatment.
Methods: DN models of rats and MPC-5 cells were established with streptozotocin (STZ) and high glucose (HG) in vivo and in vitro, respectively. Cell markers desmin and nephrin in foot kidney tissue were detected by Western blot. CCNG1 level in vitro was analyzed by Western blot and immunohistochemistry. CCK-8 assay and flow cytometry were conducted to analyze the effect of CCNG1 on HG-treated MPC-5 cells. Apoptosis-related proteins (Bcl-2, Bax and p53), CCNG1, and MDM2 were determined by RT-qPCR and Western blot.
Results: The level of nephrin was decreased, while desmin was increased in STZ-induced DN rats and CCNG1 level was also enhanced by STZ. In vitro experiments indicated that MPC-5 cell viability was inhibited and apoptosis was induced by HG and we also found that CCNG1 expression was up-regulated by HG and negatively correlated with MDM2 level. The effects of HG on MPC-5 cell viability, apoptosis, and cell cycle were reversed by silencing CCNG1, but further deteriorated by overexpression of CCNG1. Furthermore, overexpression of MDM2 inhibited HG-induced MPC-5 cell injury and CCNG1 expression.
Conclusions: These findings revealed that down-regulation of CCNG1 has protection effects in DN that is mechanistically linked to MDM2-p53 pathways.
Keywords: CCNG1; Diabetic nephropathy; High glucose; MDM2; p53.