HIF-1α activated the signalling pathways controlling IL-33 expression.

<p>A-B, HIF-1α overexpression synergized with TNF-α and IL-1β to induce the activation of ERK and p38 pathways. RASF were transfected with pcDNA3.1 or pcDNA3.1-HIF-1α. 24 h later, the cells were stimulated with 10 ng/ml TNF-α plus 2 ng/ml IL-1β for 5 min, 15 min, and 30 min, respectively. Then the cells were lysised for assessment of the phosphorylation of ERK (A) and p38 (B) by Western blot. C-D, Silencing HIF-1α dampened TNF-α- plus IL-1β-induced ERK and p38 signalling pathway activation. RASF were transfected with HIF-1α siRNA or the control scramble siRNA for 24 h. Then the cells were stimulated with 10 ng/ml TNF-α plus 2 ng/ml IL-1β for 5 min, 15 min, and 30 min, respectively. After that, the cells were harvested for assaying the activation of the ERK (C) and p38 (D) pathways by Western blot. The results were representative of three independent experiments.