FIGURE 4.

Loss of Mfn2 reduces the level of mitochondrial complex I protein and affects electron transport. A, Seahorse coupling assay showing oxygen consumption rates (OCR) in mitochondria isolated from WT and Mfn2^MKO Sol muscles. B, Quantification of OCR in state II_base (Basal respiration), state III_ADP (ADP-stimulated respiration), state IVo (non-ADP-stimulated respiration, after oligomycin treatment), and state IIIu (uncoupled respiration, after FCCP treatment) (n = 3 pairs of mice). C, Seahorse electron transport chain assay showing oxygen consumption rates (OCR) in mitochondria isolated from WT and Mfn2^MKO Sol muscles. D, Quantification of OCR in complex I, complex II, and complex IV (n = 3–5 pairs of mice). E, Western blots showing the protein levels of complexes I (NDUFB8), II (SDHB) III (UQCRC2), IV (MTCO1) and V (ATP5A) in TA, EDL, Sol and Gas muscles of WT and Mfn2^MKO mice. F, Quantification of the relative levels of complex I (normalized to GAPDH) in TA, EDL, Sol, and Gas muscle (n = 4–6 pairs of mice). All data are shown as mean ± SEM (t test: *P < .05, **P < .01)