Figure 3.

Hypoxia inducible factor‐1α (HIF‐1α) promotes intestinal epithelial interleukin (IL)−33 expression. (a) HT‐29 cells were treated with dimethyloxalylglycine (DMOG) (1 μM) or vehicle for 24 h, and the mRNA levels of IL‐33 were determined by quantitative real‐time–polymerase chain reaction (qRT–PCR). ^* P < 0·05 versus controls. (b) HT‐29 cells were transfected with HIF‐1α specific siRNA or the scramble siRNA, and the levels of IL‐33 mRNA were determined by qRT–PCR. Glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH) was used as a housekeeping gene. ^* P < 0·05 versus controls. (c) HT‐29 cells were co‐transfected with IL‐33‐pro and HIF‐1α transcription factor (TF), pGL3‐basic vector and HIF‐1α TF, IL‐33‐pro and HIF‐1α TF‐NC, pGL3‐basic vector and HIF‐1α TF‐NC, and the luciferase activity was measured and normalized to Renilla activity (left panel). ^* P < 0·05. HT‐29 cells were co‐transfected with HIF‐1 TF together with IL‐33‐pro wild‐type (WT), IL‐33‐pro (Mut.A), IL‐33‐pro (Mut.B) or IL‐33‐pro (Mut.C) (right panel). ^* P < 0·05. Relative luciferase activity of each construct was measured and normalized to Renilla activity. Data represent mean ± standard error of the mean (s.e.m.) from three independent experiments. [Colour figure can be viewed at wileyonlinelibrary.com]