MiR-133 inhibits kidney injury in rats with diabetic nephropathy via MAPK/ERK pathway

X. Shao, W.-X. Kong, Y.-T. Li

Department of Nephrology, Suzhou Kowloon Hospital, Medical School of Shanghai Jiaotong University, Suzhou, China. 385534405@qq.com

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• Nephrology

OBJECTIVE: The aim of this study was to explore the effect of micro ribonucleic acid (miR)-133 on kidney injury in rats with diabetic nephropathy (DN) through the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway.

MATERIALS AND METHODS: The model of DN was first established in rats. Blood glucose, renal index, urinary micro-albumin (UMA), and creatinine clearance rate (CCr) were detected. Meanwhile, the protein expression levels of miR-133, kidney injury molecule-1 (KIM-1) and anti-inflammatory cytokine interleukin-8 (IL-8) were measured using Western blotting. Human renal proximal tubular epithelial cell line human kidney-2 (HK-2) was treated with high glucose to simulate DN cells in vivo. Subsequently, Western blotting was performed to detect the protein expression of KIM-1. After HK-2 cells were treated with high glucose and silenced miR-133 for 24 h, the expression changes in KIM-1 was evaluated.

RESULTS: In DN group, blood glucose, renal index, UMA, and CCr were all markedly higher than those of control group. This indicated the successful establishment of DN model in rats. The expression level of miR-133 was significantly up-regulated in DN model rats. Meanwhile, the downstream protein phosphorylated-EPK (p-EPK) showed a significantly increasing trend as well. Additionally, the protein expressions of KIM-1 and IL-8 were notably elevated. High-glucose-treated HK-2 cells showed significantly up-regulated expression levels of miR-133, KIM-1, and IL-8. After 24 h of combined treatment with high glucose and miR-133 silence, the expressions of KIM-1 and IL-8 were markedly down-regulated.

CONCLUSIONS: MiR-133 may be related to the occurrence and development of DN. The silence of miR-133 inhibits kidney injury in DN via the MAPK/ERK signaling pathway. Our findings suggest that miR-133 may be an effective target for the treatment of DN.

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