Branched Chain Amino Acids Protects Rat Mesangial Cells from High Glucose by Modulating TGF-β1 and BMP-7

Abstract

Xiujuan Zhang,1 Dandan Liu,2 Yong He,3 Kai Lou,4 Dongmei Zheng,1 Wenxia Han1 1Department of Endocrinology, Shandong Provincial Hospital Affiliated to Shandong University, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, People’s Republic of China; 2Department of Respiratory and Intensive Care Unit, Shandong Provincial Chest Hospital, Jinan, People’s Republic of China; 3School of Management, Shandong University of Traditional Chinese Medicine, Jinan, People’s Republic of China; 4Department of Endocrinology, Jinan Central Hospital Affiliated to Shandong University, Jinan, People’s Republic of ChinaCorrespondence: Dongmei Zheng; Wenxia HanDepartment of Endocrinology, Shandong Provincial Hospital Affiliated to Shandong University, 324 Jing 5 Road, Jinan, Shandong Province 250021, People’s Republic of ChinaTel [phone]Email [email protected]; [email protected]: Branched-chain amino acids (BCAAs) have been reported owning curative effects in early diabetic nephropathy. However, the mechanisms of its action have not been elucidated. The aim of this study is to investigate the effect of possible mechanism(s) of BCAAs on cultured rat mesangial cells (RMCs).Methods: RMCs were treated with high glucose (30 mmol/L) and BCAAs (10 mmol/L) respectively. Cell proliferation was detected using an MTT assay. Expression of transforming growth factor (TGF)-β1 and gremlin mRNA was detected by semiquantitative reverse-transcription (RT) PCR. TGF-β1 and fibronectin (FN) protein levels were measured using enzyme-linked immunosorbent assays (ELISAs). Gremlin, bone morphogenic protein (BMP)-7, and Smad2/3 proteins were detected by immunofluorescence. Smad1/5/8 and phosphorylated (p)-Smad1/5/8 were detected by Western blotting.Results: The proliferation rate of the RMCs in the high glucose group alone was 1.45-times of cells in the CON group, and it was reduced by 32% upon co-treatment with BCAAs. The expression of TGF-β1, gremlin, p-Smd2/3 and FN mRNA or protein in the HG group was higher than that in the CON group. In the BCAAs group, the corresponding levels were lower than that in HG group. The expression of BMP-7 and p-Smad1/5/8 were significantly lower in the HG group than in the CON group. Moreover, the expression of BMP-7 and p-Smad1/5/8 were higher in the BCAAs group than in the HG group.Conclusion: BCAAs showed an antidiabetic effect via reducing TGF-β1-Smad2/3 pathway and Gremlin expression and upregulating BMP-7-Smad1/5/8 pathway in rat mesangial cells, consequently lessening ECM deposition in renal tissue.Keywords: diabetic nephropathy, branched chain amino acids, TGF-β1, BMP-7, Smad

Keywords

• diabetic nephropathy；branched-chain amino acids；tgf-β1；bmp-7；smad