Department of Nephrology, Affiliated Hospital of Guizhou Medical University, No. 28 Guiyi Street, Yunyan District, Guiyang, 550004, Guizhou Province, China.
Int Urol Nephrol. 2020 Mar;52(3):581-593. doi: 10.1007/s11255-020-02383-4. Epub 2020 Feb 3.
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.
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.
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.
These findings revealed that down-regulation of CCNG1 has protection effects in DN that is mechanistically linked to MDM2-p53 pathways.
糖尿病肾病（DN）是糖尿病最严重的并发症之一，也是终末期肾病的重要原因之一，但目前其发病机制尚未阐明，也没有有效的治疗方法。
分别采用链脲佐菌素（STZ）体内和高糖（HG）体外建立大鼠 DN 模型和 MPC-5 细胞模型。采用 Western blot 检测足肾组织细胞标志物结蛋白和足细胞裂孔膜蛋白nephrin。采用 Western blot 和免疫组化分析 CCNG1 在体外的水平。通过 CCK-8 检测和流式细胞术分析 CCNG1 对 HG 处理的 MPC-5 细胞的影响。采用 RT-qPCR 和 Western blot 检测凋亡相关蛋白（Bcl-2、Bax 和 p53）、CCNG1 和 MDM2。
STZ 诱导的 DN 大鼠中 nephrin 水平降低，desmin 水平升高，CCNG1 水平也升高。体外实验表明，HG 抑制 MPC-5 细胞活力并诱导其凋亡，同时发现 HG 上调 CCNG1 的表达，且与 MDM2 水平呈负相关。沉默 CCNG1 可逆转 HG 对 MPC-5 细胞活力、凋亡和细胞周期的影响，但过表达 CCNG1 则进一步加重其影响。此外，过表达 MDM2 抑制 HG 诱导的 MPC-5 细胞损伤和 CCNG1 表达。
这些发现表明，下调 CCNG1 在 DN 中具有保护作用，其机制与 MDM2-p53 通路有关。
