β-oxidation in mitochondria from white SM is stimulated or inhibited by Acot2 loss, depending on lipid supply
A. Oxygen consumption (JO2) in mitochondria from white SM, isolated from chow-fed, and supplied with 20 µM PCarn and 0.1 mM malate. The creatine kinase clamp approach was used to simulate changes in ATP demand (ADP/ATP) by varying phosphocreatine (PCr) concentration. Values: mean ± s.e.m..
B. The data from (A) were expressed as a function of Gibbs free energy for ATP (ΔGATP). The slope reflects the conductance. Right panel: conductance; bar chart are mean ± s.e.m., individual points are from individual mice; p value: unpaired t-test, n=7/genotype.
C. Left panel: JO2 measured in white SM mitochondria, with saturating [ADP] and 20 or 40 µM PCarn (plus 0.1 mM malate). Statistics: two-way ANOVA and multiple comparisons (q values) with correction for FDR (0.05; Benjamini, Krieger, Yekutieli method): * 0.05 ≤ q ≤ 0.03, ** 0.01 ≤ q < 0.03; n=7/genotype. Right panel: bar chart showing the difference in JO2 (ΔJO2) for 40 vs. 20 µM PCarn. p value: unpaired t-test, n=7/genotype.
D. Left panel: JO2 measured in white SM mitochondria, with saturating [ADP] and 20 µM PCarn (plus 0.1 mM malate), showing measurements 6 and 18 minutes after ADP addition. Note: 6 minutes data for both genotypes are the same data shown in Panel C (20 µM PCarn) Statistics: two-way ANOVA and multiple comparisons (q values) with correction for FDR (0.05; Benjamini, Krieger, Yekutieli method): *** q < 0.01; n=7/genotype. Right panel: bar chart showing the difference in JO2 (ΔJO2) for 18 vs. 6 minutes; p value: unpaired t-test, n=7/genotype.
E. Left panel: JO2 measured in white SM mitochondria, with saturating [ADP], 10 mM pyruvate and 5 mM malate (saturating [substrate]), measured 6 minutes after ADP addition. Middle panel: Difference in ADP-driven JO2 (ΔJO2) for 18 vs. 6 minutes Right panel: JO2 after addition of oligomycin to inhibit the ATP synthase. All panels: p value: unpaired t-test, n=7/genotype.
F. JO2 measured in white SM mitochondria fueled by 20 or 40 µM PCarn (and 0.1 mM malate), after addition of oligomycin to inhibit the ATP synthase. Statistics: two-way ANOVA and multiple comparisons (q values) with correction for FDR (0.05; Benjamini, Krieger, Yekutieli method): ** 0.01 ≤ q < 0.03; n=7/genotype.
G. Left panel: scheme illustrating the approach to evaluate proton leak in isolated mitochondria. Mitochondrial membrane potential (Δψm) and JO2 in the presence of oligomycin were measured in parallel in each preparation of mitochondria from white SM. Antimycin (inhibits Complex III of the ETC) was used to decrease the driving force. Middle panel: Proton leak measured in mitochondria fueled with 20 µM PCarn and 0.1 mM malate. Right panel: Same experiment as in Middle panel, except using 40 µM PCarn and 0.1 mM malate. Middle and right panels: insets show bar chart of mean (±s.e.m.) Δψm and JO2 at the arrow; p value: unpaired t-test, n=6/genotype.
Panels B, C, D, E, F: Bar chart: mean ± s.e.m., individual points show data from each mice.