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. 2023 Jan 13;68:101670. doi: 10.1016/j.molmet.2023.101670

Figure 1.

Figure 1

Skeletal muscle expression of ERRs, and loss of ERR and ERR targets in skeletal muscle - specific ERR KO mouse models. (A) ERRβ and ERRγ mRNA levels in muscle biopsies taken from human male subjects (n = 7) before (Pre) or 3 h after (Post) an acute cycling bout (60 min at ∼70% of their VO2 peak) were quantified by RT-qPCR as described [28]. (B) ERR mRNA levels in biceps femoris (BF), extensor digitorum longus (EDL), gastrocnemius (GC) and soleus of 8-week-old male mice (n = 3) were determined by RT-qPCR and expressed as mean ± SD of ERR mRNA copy number per 1,000 copies of 36B4 mRNA. Numbers above bars represent Ct (threshold cycle) values for each ERR isoform in the different muscles. (C) Relative ERR mRNA levels in GC of WT or littermate mice with skeletal muscle-specific deletions of ERRα (ERRα mKO), ERRβ and ERRγ (ERRβ/γ dmKO), or ERRα and ERRγ (ERRα/γ/dmKO), normalized to levels of 36B4 mRNA, and expressed relative to the levels of each gene in WT muscle. (D) Protein levels of OxPhos complexes I–V and ponceau stain (for loading control) in lysates of GC muscles from ERRα mKO, ERRβ/γ dmKO, ERRα/γ/dmKO and control WT littermates. (E) Relative mRNA levels of ERR-regulated genes Chchd10, Idh3a and Cox7a1, acting in oxidative phosphorylation (OxPhos) and/or the tricarboxylic acid (TCA) cycle. ∗∗, p < 0.01; ∗∗∗, p < 0.001 for differences in mRNA levels (post vs. pre-exercise in A; ERR KO vs. WT littermates in C&E).