Fig. 3: Taurine represses expression of ASL via FOS.

A Putative FOS:JUN binding consensus sequences in promoter of ASL (bottom) were compared with motif predicted using JASPAR database (top). B, C MHCC97H cells were treated with or without 100 μM taurine for the indicated days. Immunoblotting analysis was performed using the indicated antibodies (B). mRNA levels of FOS were analyzed (C). D Plasmid containing either WT or mutant promoter sequence of ASL was co-transfected with FOS into 293T cells. Dual luciferase reporter assay was performed. E, F MHCC97H cells were transfected with or without sgRNA targeting FOS (sgFOS) and treated with or without 100 μM taurine for four days. Immunoblotting analysis was performed using the indicated antibodies (E). mRNA levels of ASL were analyzed (F). G ChIP assay was performed in sgCtrl and sgFOS MHCC97H cells using antibodies against c-JUN. DNA enrichment was examined by quantitative real-time PCR. The y axis shows the value normalized to input. H-J sgCtrl and sgFOS MHCC97H cells were treated with or without 100 μM taurine for four days. Arginine and urea levels (H) ammonia levels (I) and urea release (J) were analyzed. K Cell viability of sgCtrl and sgFOS MHCC97H cells treated with or without 100 μM taurine for indicated days were analyzed. Data are presented as mean ± SD, n = 3 independent repeats. Unpaired, two-tailed t test; ^*P < 0.05; ^**P < 0.01. NS, not significant.