Figure 3.

REDD1 loss potentiates fatty acid oxidation (FAO) to drive metabolic dependencies on redox and energy homeostasis. (A) Schematic showing proposed pathways linking FAO to redox and energy homeostasis. (B) Increased FAO in primary KRMEFs compared with KMEFs under serum starvation for 3 h as measured by ³H palmitate labeling. Bar graph shows mean of three experiments. Error bars indicate SD. (C) Rapid ATP depletion in KRMEFs compared with KMEFs with FAO inhibition by etomoxir treatment (250 µM) for 1 h, assessed by ATP Cell Titer-Glo assay. Bar graph shows mean from duplicate experiments. (D) Increased NADPH/NADP⁺ ratio in KRMEFs compared with KMEFs, assessed as described in the Materials and Methods. Graph shows mean of two experiments performed in duplicate. (E) Increased NADPH/NADP⁺ ratio in REDD1-ablated primary KPECS. Bars indicate mean of two experiments performed in duplicate. (F) Increased GSH concentration and GSH/GSSG ratio in KRMEFs as compared with KMEFs. (G) REDD1 ablation renders KPECs resistant to glutamine withdrawal. Cells were cultured in the denoted concentrations for 3 d. Data represents mean of three independent experiments. See also Supplemental Figure S3. Unless noted otherwise, all error bars denote SD. (*) P < 0.05; (**) P < 0.01; (***) P < 0.001; (****) P < 0.0001 by two-tailed t-test for all panels.