Figure 2

Up-regulation of thioredoxin gene expression by IFN-γ in monocytic cells. A. Dose-dependent induction of thioredoxin mRNA by IFN-γ. THP1 monocytic cells (5 × 10⁶) were treated with varying doses of IFN-γ in complete media for 24 h, after which the RNA was isolated and the thioredoxin gene expression was analyzed by Northern blot analysis as described in Fig 1. Panel a: Northern blot autoradiogram. Panel b: Densitometric analysis of the data in panel a. The values represent the fold induction of thioredoxin mRNA levels, which were calculated after normalization against β-actin by taking the untreated control value as 1. B. Kinetics of thioredoxin gene induction by IFN-γ and the effect of cycloheximide. Panel a: THP1 cells were treated with IFN-γ (10 ng/ml) in complete media for the indicated time periods, after which the RNA was isolated and analyzed for thioredoxin gene expression by Northern blot analysis as described in Fig 1. Panel b: THP1 cells that had been maintained in complete media were washed thoroughly and then treated with IFN-γ (10 ng/ml) under serum-free conditions ("serum-free") or serum starved conditions for 48 h prior to IFN-γ treatment ("serum-starved"). The cells were then harvested after the indicated time periods, after which their thioredoxin mRNA levels were determined by Northern blot analysis. Panel c: THP1 cells were treated with IFN-γ under serum-free conditions as described for panel b, with or without pretreatment with cycloheximide (30 μg/ml) for 3 h. The cells were then cultured for an additional 4 h following IFN-γ treatment, after which the thioredoxin mRNA levels were determined by Northern blot.