Figure 2A. Representative images of mice and body weight graph following the expression of mitochondrial ATPIF1H49K (days of doxycycline) (wt, n= 12; LowOXPHOS, n= 12). B. Representative images of hindlimb muscles. Arrows point to the soleus. (C, D) Transversal slices of red fibers from soleus stained with hematoxylin/eosin (C). Higher im-WAT infiltrations in LowOXPHOS mice are shown. Quantifications in D (wt, n= 6; LowOXPHOS, n= 6; 10 fields/mouse). iTRAQ ratio (E) of Skm proteins from de novo lipid synthesis. The expression of ATP citrate lyase (ACLY), acetyl-CoA carboxylase (ACAC), fatty acid synthase (FASN) are shown. Two samples per condition; each sample contains protein extracts from 3 mice. In E, a higher intensity of red color represents a higher LowOXPHOS/wt expression ratio. representative WB expression (F) of Skm proteins from de novo lipid synthesis. The expression of ATP citrate lyase (ACLY), acetyl-CoA carboxylase (ACAC), fatty acid synthase (FASN) and their phosphorylation (p) are shown. Two samples per condition; each sample contains protein extracts from 3 mice. GAPDH is shown as a loading control. Quantifications in lateral histograms (wt, n= 6; LowOXPHOS, n= 6). G. Immunocapture (IP) of Skm acetylated proteins blotted with anti-ACLY antibody. H. Skm acetyl-CoA amounts (wt, n= 8; LowOXPHOS, n= 8). Data information: Bars are the mean ± s.e.m. of the indicated (n) mice/genotype *p <0.05 when compared to wt by ANOVA and Student's t-test. I. Schematic representation of de novo FFA synthesis and the increase in LD. Elevated acetyl-CoA levels may be derived from dysregulation of the FFA β-oxidation, glycolysis or BCAA metabolism. J. Myocyte rates of aerobic glycolysis to lactate production. Bars are the mean ± s.e.m. of n= 3 experiments, 9 replicas/condition. Data information: Bars are the mean ± s.e.m. of the indicated (n) mice/genotype *p <0.05 when compared to wt by ANOVA and Student's t-test. (K, L). 14C(u)-glucose uptake (K) and oxidation to CO2 (L) in myocytes expressing or not the ATP synthase inhibitor ATPIF1H49K. Bars are the mean ± s.e.m. of n= 3 experiments, 6 replicas/condition. Data information: Bars are the mean ± s.e.m. of the indicated (n) mice/genotype *p <0.05 when compared to wt by ANOVA and Student's t-test. M. Representative WB expression of Skm PDH and its phosphorylation. Two samples per condition; each sample contains extracts from 3 mice. Quantification in histograms (wt, n= 6; LowOXPHOS, n= 6). Data information: Bars are the mean ± s.e.m. of the indicated (n) mice/genotype *p <0.05 when compared to wt by ANOVA and Student's t-test. N. Skm levels of lactate (wt, n= 6; LowOXPHOS, n= 6). Data information: Bars are the mean ± s.e.m. of the indicated (n) mice/genotype *p <0.05 when compared to wt by ANOVA and Student's t-test. O. FFA β-oxidation in primary cultures of myocytes derived from wt or LowOXPHOS mouse hindlimbs. Bars are the mean ± s.e.m. of n= 3 experiments, 9 replicas/condition. Data information: Bars are the mean ± s.e.m. of the indicated (n) mice/genotype *p <0.05 when compared to wt by ANOVA and Student's t-test. P. FFA amounts in Skm extracts (wt, n= 8; LowOXPHOS, n= 8). Data information: Bars are the mean ± s.e.m. of the indicated (n) mice/genotype *p <0.05 when compared to wt by ANOVA and Student's t-test. Transversal slices of soleus stained with hematoxylin/eosin (Q). Arrows indicate LDs in LowOXPHOS mice. Images are representative of n= 4 mice/genotype, 10 images/mouse. Oil Red O staining and enzymatic activity of respiratory CI in transverse contiguous slices (R). Images are representative of n= 4 mice/genotype, 10 images/mouse. Note the colocalization of oxidative fibers with LDs (R). S. Electron microscopy of transversal slices of the soleus. Intrafiber LDs surrounded by mitochondria in LowOXPHOS mice are shown. Histogram shows the quantifications of n= 4 animals/genotype, 10 images/animal. T. LD formation upon ATP synthase inhibition (ATPIF1H49K) in starved myocytes after 24 hours of palmitate supplementation in the presence or absence of BCAA. Blue: DAPI, nuclei; green: BODIPY-positive LDs. Histograms show the quantification expressed as the number of LDs/nuclei. Bars are the mean ± s.e.m. of n= 3 experiments, 12 fields/condition. U. LD formation upon ATP synthase inhibition (5µM oligomycin) in myocytes after 24 hours of palmitate supplementation. Histograms show the quantification expressed as fold of control of the BODIPY/DAPI fluorescence intensity. 7 fields/condition. Data information: Bars are the mean ± s.e.m. of the indicated (n) mice/genotype *p <0.05 when compared to wt by ANOVA and Student's t-test.