FIGURE 2.

Mfn2-null myoblasts exhibit abnormal respiratory capacity and elevated reactive oxygen species. A, Strategy for myoblast-specific deletion of Mfn2 driven by Myod1^Cre (Mfn2^MKO). B, Immunofluorescence staining and Western blotting confirm the loss Mfn2 expression in Mfn2^MKO primary myoblasts, scale bar: 20 μm. C, Mito-tracker staining of mitochondria in WT and Mfn2^MKO myoblasts. Scale bar: 10 μm. D and E, qRT-PCR analysis showing the ratio of mitochondria DNA to nucleotide DNA (E) and mRNA levels of Mfn1 (F) in WT and Mfn2^MKO myoblasts (n = 4 for each group). F, Seahorse cell assay showing oxygen consumption rates (OCR) between WT and Mfn2^MKO primary myoblasts. G, Quantification of OCR in basal respiration (BR), ATP production (ATP), proton leak (PL), maximal respiration (MR), and spare respiratory capacity (SRC) (n = 6 each group). H, Fluorescence staining showing reactive oxygen species (ROS) in WT and Mfn2^MKO myoblasts. White arrows indicate ROS positive myoblasts. Scale bar: 20 μm. I, Quantification of ROS intensity in WT and Mfn2^MKO myoblasts (n = 4 each group). All data are shown as mean ± SEM (t test: *P < .05, **P < .01)