γ-Secretase inhibitor DAPT reduces aristolochic acid-induced phenotypic transformation by inhibiting Notch pathway in renal tubular epithelial cells / 中国药理学与毒理学杂志

ABSTRACT

OBJECTIVE To investigate the effect ofγ-secretase inhibitor N-[N-(3,5-difluorophen?acetyl)-L-alanyl]-S-phenylglycine t-butyl ester(DAPT)on phenotypic transformation and matrix accu?mulation induced by aristolochic acid(AA) in renal tubular epithelial cells(NRK-52E)and explore the mechanism. METHODS NRK-52E cells were divided stochastically into normal cell control group,AA 10 mg·L-1 group and AA 10 mg·L-1+DAPT 1 and 10μmol·L-1 group. After 24 h,the mRNA expressions of Notch1,Jagged1,Numb,E-cadherin,transforming growth factor-β1(TGF-β1),α-smooth muscle actin(α-SMA),bone morphogenic protein 7 (Bmp7),typeⅠ a1 (Col1a1) and Ⅲ collagens a1 (Col3a1)were quantified by quantitative real-time RT-PCR. The protein expressions of Notch1,Jagged1,α-SMA,and Col3a1 in NRK-52E cel s were detected by immunofluorescence staining. RESULTS In NRK-52E cells,AA enhanced the expression of TGF-β1,α-SMA and Col3a1 mRNA(P<0.05),reduced the expression of E-cadherin mRNA(P<0.05),up-regulated the mRNA expression of Notch1 mRNA(P<0.01)and Jagged1(P<0.05),and down-regulated the mRNA expression of Numb mRNA(P<0.05) compared with normal cell control group,indicating that phenotypic transformation and matrix accumu?lation occurred in AA-treated NRK-52E cells,accompanied by activated Notch signaling. Treatment with DAPT inhibited Notch signaling by decreasing the expression of Notch1 and Jagged1 (P<0.05),and increasing the expression of Numb mRNA(P<0.05). Furthermore, DAPT also down-regulated the expression levels of TGF-β1,α-SMA,Col1a1 and Col3a1 mRNA(P<0.05), and up-regulated the expression level of Bmp7 and E-cadherin mRNA(P<0.05) compared with AA group,suggesting that DAPT inhibited phenotypic transformation and matrix accumulation in AA-treated NRK-52E cells. CONCLUSION AA induces phenotypic transformation and matrix accumulation in renal tubular epithelial cells,which is inhibited by DAPT treatment. The possible mechanism is that DAPT suppresses the activation of Notch signaling,resulting in the reduction of epithelial-to-mesenchymal transition and matrix deposition.