Smac Involved in Promoting TGF-β1 Treated Mesangial Cells Apoptosis Induced by Triptolide / 天津医药

ABSTRACT

Objective To investigate the effects of Triptolide on apoptosis of cultured rat mesangial cells treated by TGF-β1 and the role of Smac in this process. Methods The mesangial cells were pre-treated with different concentrations of Triptolide for 24 hours, then stimulated with TGF-β1 for 24 hours. Apoptotic cells were detected by TUNEL assay. Smac transcription level was determined by Real time-PCR analyses. Smac expression level was assessed using Western blot anal-yses. Localization of Smac was shown by confocal fluorescence microscopy. Results Compared with control group, TGF-β1 inhibited apoptosis and Smac transcription and expression in rat mesangial cells. By contrast, Triptolide promoted mesangial cells apoptosis. In Triptolide groups, Smac mRNA and protein levels were up-regulated. Additionally, in normal and TGF-β1 groups Smac protein was mainly localized in mitochondriawhile in Triptolide groupit was mainly localized in cytoplasm and nucleus with increased fluorescence intensity. Conclusion Triptolide could promote the effect that TGF-β1 inhibited apop-tosis of mesangial cells, through both up-regulation the expression of Smac and stimulating it translocation from mitochon-dria to cytoplasm and nucleus.