Abstract:

Objective To investigate the inhibitory effect of fermented red ginseng total saponins （FRGTS） on the epithelial-mesenchymal transition（EMT） of renal tubular epithelial cells induced by high glucose， and to clarify its mechanisms. Methods The rat renal tubular epithelial cells NRK-52E were divided into normal control group （5.5 mmol·L^－1 D-glucose）， high glucose group（30.0 mmol·L^－1 D-glucose）， silent information regulator 1 （SIRT1） inhibitor EX527 group （30.0 mmol·L^－1 D-glucose+10 μmol·L^－1 EX527）， FRGTS group （30.0 mmol·L^－1 D-glucose+25 mg·L^－1 FRGTS） and EX527+FRGTS group （30.0 mmol·L^－1 D-glucose+10 μmol·L^－1 EX527+25 mg·L^－1FRGTS）. Immunofluorescence method was used to detect the expression levels of E-cadherin and α-smooth muscle actin （α-SMA） protein in the cells in various groups. Real-time fluorescence quantitative PCR（RT-qPCR） method was used to detect the expression levels of E-cadherin， α-SMA and SIRT1 mRNA， ELISA method was used to detect the levels of collagen type Ⅰ （ColⅠ） in culture supernatant， and Western blotting method was used to detect the expression levels of SIRT1， transforming growth factor-β1 （TGF-β1） and Smad3 proteins in the cells in various groups. Results After 48 h of high glucose culture， compared with normal control group， the expression levels of E-cadherin mRNA and protein in the NRK-52E cells in high glucose group were decreased （P<0.01）， the expression levels of α-SMA mRNA and protein were increased （P<0.01）， the level of ColⅠ in culture supernatant was increased（P<0.01），the expression levels of SIRT1 mRNA and protein were significantly decreased （P<0.01），and the expression levels of TGF-β1 and Smad3 proteins were increased（P<0.01）. Compared with high glucose group， the expression level of E-cadherin mRNA in the NRK-52E cells in FRGTS group was increased（P<0.01）， the expression level of α-SMA mRNA was decreased （P<0.05）， the level of ColⅠ in culture supernatant was decreased（P<0.05），the expression levels of SIRT1 mRNA and protein were increased （P<0.05 or P<0.01），and the expression levels of TGF-β1 and Smad3 proteins were decreased （P<0.05 or P<0.01）. Compared with FRGTS group，the expression level of E-cadherin mRNA in the cells in EX527+FRGTS group was significantly decreased（P<0.01），the expression level of α-SMA mRNA was increased（P<0.05），the level of ColⅠ in culture supernatant was increased（P<0.05），the expression levels of SIRT1 mRNA and protein were significantly deceased（P<0.01），and the expression levels of TGF-β1 and Smad3 were significantly increased（P<0.01）. Conclusion FRGTS can upregulate the expression of SIRT1 and then inhibits TGF-β1/Smad signaling pathway， which effectively inhibits the EMT of renal tubular epithelial cells.

Key words: Fermented red ginseng total saponins, Epithelial-mesenchymal transition, Silent information regulator 1, Transforming growth factor-β1, Smad, Renal tubular epithelial cells