Fig. 2
Transforming growth factor (TGF)-β modulates interleukin (IL)-13 mRNA steady-state levels by acting on IL-13 gene transcription. a Jurkat T cells were cultured in 0.5 % fetal calf serum (FCS)-containing medium for 16 h before addition of human recombinant TGF-β for the indicated time periods. IL-13 mRNA expression was measured by RT-PCR. The results are presented as mean percentage (±SD) of IL-13 expression measured in the presence of TGF-β (dark bars) relative to the respective IL-13 expression detected at the same time in the absence of TGF-β (white bars) and reported to 100 to allow comparison between time arrests. The results are representative of three independent experiments. *p < 0.05; **p < 0.01. b Following culture in 0.5 % FCS-containing medium for 16 h, Jurkat T cells were treated with (dark dots) and without (white dots) TGF-β for 4 h. In order to stop ongoing transcription, actinomycin D was then added (squares) or not (triangles) for a 1-, 3- and 5-h further incubation. IL-13 mRNA expression was analyzed by quantitative RT-PCR. The results are presented as comparative cycle threshold (∆Ct), an arbitrary value from three independent experiments. c Jurkat T cells were transfected with pGL3 2666-bp IL-13 promoter construct/Luciferase (2666 bp-IL-13-Lux) promoter-containing plasmid. Cells were then treated (dark bars) or not (white bars) with TGF-β in 0.5 % FCS-containing medium for 24 h. The results are presented as mean percentage (±SD) of 2666 bp-IL13-Lux promoter activity detected in the presence of TGF-β relative to respective activity without TGF-β and reported to 100. The results are representative of six independent experiments. ***p < 0.001