Figure 4.

STC1-mediated reduction of ROS is dependent on UCP2. (a) A549 cells were transfected with siRNA-targeting UCP2 and assayed for UCP2 by real-time PCR (upper panel) and western blot assays (lower panel). (b) A549 cells were cultured in H₂O₂ (100 µmol/l) and transfected with control, UCP2 or STC1 directed siRNA. For each condition, cells were tested for the ability of rSTC1 to promote viability. (c) A549 cells were transfected with siRNA-targeting UCP2 or a scrambled siRNA control (siSCR) and cultured in medium containing H₂O₂ (100 µmol/l) and rSTC1 (50 ng/ml). After 4 hours, cells were assayed for ROS using carboxy-H2DCFDA. Left panel: representative flow cytometry images. Right panel: quantification of flow cytometry data from multiple experiments. GAPDH, glyceraldehyde 3-phosphate dehydrogenase; qRT-PCR, quantitative reverse transcription-PCR; ROS, reactive oxygen species; siRNA, short interfering RNA; STC1, stanniocalcin-1; UCP2, uncoupling protein 2.