Resveratrol transcriptionally regulates miRNA-18a-5p expression ameliorating diabetic nephropathy via increasing autophagy.

OBJECTIVE: To investigate the effects of resveratrol on autophagy in the chronically diabetic nephropathy and to study the effects of the different expression of microRNAs after resveratrol (RSV) treated in db/db mice (diabetic mice).
MATERIALS AND METHODS: Db/m (non- diabetic) and db/db mice were randomly divided into intra gastric RSV treatment group or control group. Renal tissues were prepared for HE/PAS staining. In vitro, mouse podocytes cell lines were grown in different mediums with different dose of resveratrol treatment. microRNA (miRNA) gene chips assay was performed for differentially expressed miRNAs screening. Western blot was used to detect protein levels.
RESULTS: In vivo, RSV significantly decreased urinary albumin, serum creatinine, mesangial area and glomerular size in db/db mice. After RSV treatment, LC3-II/LC3-I and synaptopodin were increased while cleaved-caspase 3 was decreased in kidney tissues. In vitro, podocytes treated with RSV exhibited significantly increased LC3-II/LC3-I and decreased cleaved caspase 3. Moreover, this effect of RSV can be enhanced by rapamycin (RAPA, an activator of autophagy) but partially reversed by 3-MA (an autophagy inhibitor). Further, we found that miR-18a-5p was significantly upregulated after RSV treatment in db/db mice. Overexpression of miR-18a-5p in podocytes resulted in significant inhibition of cleaved-caspase 3 protein, and increased the ratio of LC3-II/LC3-I. Dual luciferase report assay validated that Atactic telangiectasis mutation (ATM) was a target of miR-18a-5p. In podocytes, downregulation of cleaved caspase 3 and the enhanced ratio of protein LC3-II/LC3-I were detected in cells transfected with ATM siRNA.
CONCLUSIONS: Role of miRNA-18a-5p in the regulation of autophagy via targeting ATM may represent a promising therapeutic target for preventing and attenuating diabetic nephropathy.