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Laboratory Study

The protective effects of rapamycin on cell autophagy in the renal tissues of rats with diabetic nephropathy via mTOR-S6K1-LC3II signaling pathway

, , , , &
Pages 492-497 | Received 05 Dec 2017, Accepted 07 Jun 2018, Published online: 11 Sep 2018
 

Abstract

Background: Previous studies have shown that podocyte autophagy is an important trigger for proteinuria and glomerulosclerosis. The mammalian rapamycin target protein (mTOR) occupies a pivotal position in the autophagy pathway. In this study, we planned to clarify the mechanism of mTOR regulation of podocyte autophagy and the effect of rapamycin (RAPA).

Methods: All rats were randomly divided into normal control group (n = 8), DN group (n = 8), and RAPA group (n = 8). Blood and urine samples were collected at the 4th, 8th, and 12th weeks of the experiment. The serum creatinine (Scr), urine volume levels, and the 24 h urine protein (UP) levels were examined. The nephrin, podocin, mTOR, ribosomal S6 kinase 1 (S6K1), and autophagy marker light chain 3 (LC3II) expression levels were evaluated by immunohistochemistry, quantitative PCR, and immunoblotting.

Results: The urine volume, 24 h UP, and Scr of the DN and RAPA groups increased significantly compared with the NC group (p < .05). Nephrin and podocin expression was decreased in the kidney tissues of the DN and RAPA groups compared with the NC group (p < .05). The expression levels of mTOR and S6K1 increased and LC3II expression decreased in the renal tissues of the DN and RAPA groups compared with the NC group (p < .05). After RAPA treatment, all the above indexes were improved compared with the DN group (p < .05), but were significantly abnormal compared with the NC group (p < .05).

Conclusion: The proteinuria and kidney function had improved after RAPA treatment. These results confirmed that RAPA specifically binds to mTOR kinase, and inhibits mTOR activity, thereby regulating the pathological autophagic process.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by Accented Project of Natural Science Research in University of Anhui Province [KJ2016A481], General Project of Natural Science Research in University of Anhui Province [KJ2015B021by], and Project of Natural Science Research of Tibet Autonomous Region [XZ2017ZR-ZYZ05].