Cycloheximide blocks TGF-beta(1)-induced apoptosis in murine hepatocytes

AIM: To study the mechanism of transforming growth factor beta (1)-induced apoptosis in cultured hepatocytes. METHODS: DNA fragmentation and fluoresce nt microscopy were used to characterize cell apoptosis. Crystal violet stai ning was used to assess cell viability. Immunoblotting was used to detect T ak1, p53, and Bax. Dual luciferase assay was used to determine TGF-beta (1) -induced gene expression. Thin layer chromatography was used to examine cer amide level in AML12 cells. RESULTS: In response to TGF-beta (1) treatment, AML12 cells exhibited typical changes, which was characteristic of apoptos is, such as condensation of chromatin, disintegration of nuclei, and DNA fr agmentation. TGF-beta (1)-induced apoptosis in AML12 cells was completely b locked in the presence of cycloheximide. The inhibitory effect of cyclohexi mide was accompanied with down-regulation of Tak1 expression and TGF-beta ( 1)-induced PAI-1 expression. TGF-beta (1) induced p53 expression but not Ba x. No increase of ceramide was obeserved in TGF-beta (1)-induced apoptosis. CONCLUSION: TGF-beta (1)-induced apoptosis requires TGF-beta (1)-induced g ene expression.