Figure 8. RIP140 is a negative regulator of cellular respiration in 3T3-L1 adipocytes.

Eight days after the induction of differentiation, 3T3-L1 adipocytes were transfected with scrambled or RIP140 siRNA. (A) After 72 hours, cells were incubated with MitoTracker Red to stain actively respiring mitochondria. Fluorescence microscopy was performed as described in Methods. Shown are representative photographs with identical exposure times. (B) Cells were assayed for respiration using the oxygen biosensor fluorescence assay described in Methods. Basal respiration is indicated on the left, and uncoupled respiration, induced by addition of the mitochondrial uncoupler carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone (FCCP; 33 μM), is shown on the right. Illustrated are the averages of 3–4 independent experiments. The respiration with or without FCCP of cells transfected with scrambled or RIP140 siRNA are considered statistically different based on the fluorescence intensity at the time when fluorescence of the leading curve was equal to half-maximum for each experiment. RFU, raw fluorescence units.