小G蛋白Rac1在马兜铃酸诱导肾小管上皮细胞损伤中的作用及意义

Function and its significance of Rac1 in aristolochic acid-induced renal tubular epithelial cellular injury

目的 :探讨马兜铃酸(AA)致肾小管上皮细胞损伤的机制及小G蛋白Rac1在此过程中发挥的作用。方法:以溶剂作为对照组,AA以浓度10μg/mL作用于大鼠肾小管上皮细胞NRK-52E,培养24 h后,WST-1法检测细胞增殖的抑制率;Hoechst 33258染色观察细胞核的形态变化;细胞免疫荧光染色检测Ⅲ型胶原和Rac1蛋白的表达;real-time RT-PCR检测TGF-β1 mRNA的表达;ELISA法检测细胞培养上清液中Rac1和TGF-β1含量,并分析两者相关性。结果:AA可明显抑制NRK-52E细胞增殖,并诱导细胞凋亡。AA以10μg/mL处理NRK-52E细胞24 h后,TGF-β1 mRNA的表达明显升高(P<0.05),并且细胞外基质成分Ⅲ型胶原的表达明显增加(P<0.05)。此外,AA也可诱导小G蛋白Rac1的表达(P<0.05)。相关分析显示,AA诱导NRK-52E细胞损伤过程中,Rac1的表达量与TGF-β1的分泌水平呈现明显正相关(r=0.967,P<0.01)。结论:AA诱导肾小管上皮细胞出现纤维化样改变,同时伴有Rac1蛋白的高表达;Rac1及其介导的信号通路可能被TGF-β1的高表达所活化,进而参与AA所致的胶原累积过程。

Objective： To investigate the molecular mechanisms of aristolochic acid （AA） -induced renal tubular epithelial cellullar （NRK-52E） injury, and to evaluate the possible role of small G protein Racl in this process. Methods： The proliferation inhibition rate was measured by WST-1 assay in NRK-52E cells treated with AA for 24 h. Hoechst 33258 staining was used to determine cell apoptosis. Cell immunofluorescent assay was applied to detect the levels of Racl and type In collagen. TGF-β1 mRNA was detected by real-time RT-PCR. ELISA assay was used to test the levels of Racl and TGF- β1, and the correlation between them was analyzed. Results： AA significantly inhibited the proliferation of NRK-52E cells, and induced cell apoptosis. The expression of TGF-β1 mRNA was markedly increased in NRK-52E cells with the treatment of AA （10 μg/mL）. Also, the expression of type In collagen was significantly increased in AA-treated cells. In addition, enhanced expression of Racl protein, an important molecular of GTPase Rho, induced by AA was observed. Moreover, there was positive correlation between Rac 1 and TGF- β1 in AA-induced collagen deposition （r=-0.967, P〈0.01）. Conclusion： AA can significantly inhibit the proliferation and induce the apoptosis of NRK-52E cells. In this process, Racl and Racl-related signaling pathways may be activated and followed by high expression of TGF-β1, and then promote collagen deposition in renal tubular epithelial cells after AA injury.