FIG. 6.

TSH did not induce IL-12 promoter activity (A). The vector containing the promoter was transfected into fibrocytes and cells were incubated with TSH for 2 h. TSH stabilized IL-12p40 mRNA (B, left panel), whereas CD40L did not affect mRNA stability (B, right panel). IL-12 mRNA production was stimulated for 12 h with TSH. Cells were then washed and treated with 50 μM of DRB alone, DRB and TSH, or DRB and CD40L (time zero). Degradation of existing mRNA was slower in the presence of TSH and DRB (●) than in the presence of DRB alone (◯), whereas mRNA degradation proceeded at similar rate in the absence (□) and presence (■) of CD40L. TSH stimulation of IL-12p40 mRNA depended on de novo protein production (C, left panel). Adding cycloheximide (10 μg/mL) 1 h before TSH stimulation significantly lowered the TSH-induced IL-12p40 mRNA expression. Adding cycloheximide did not affect CD40L stimulation of IL-12p40 mRNA (C, right panel), indicating that CD40L does not depend on de novo protein synthesis.