Figure 1.

ATF5 KO animals exhibit reduced body weights with no changes in muscle contractile properties, exercise tolerance or performance. The whole-body ATF5 KO mouse model was confirmed through A) DNA genotyping targeting the ATF5 WT (100 bp) and MUT (400 bp) alleles with designated primer sets and B) measuring ATF5 mRNA levels with qPCR. (WT: n = 16, KO: n = 23). Phenotypic characteristics of the genotypes were assessed, including C) Body weight and D) TA weight normalized for body weight, (WT: n = 18, KO: n = 26–27). Twitch kinetics were assessed with E) Maximum twitch force expressed as grams of force per milligram of muscle weight (g/mg), F) Time to peak and G) Half relaxation time (1/2 R T) in milliseconds (ms). Muscle force was further examined with H) Maximum tetanic force (g/mg) (n = 5). I) Blood lactate levels in CON and EX animals subjected to acute exhaustive exercise (n = 4–13). J) Exercise performance was observed from distance to exhaustion recordings from an incremental exhaustive exercise test on the treadmill (n = 4–7). ∗∗∗∗P < 0.0001, unpaired t-test. bp, base pairs; CON, control; EX, exercised; GW, gastrocnemius weight; KO, knockout; MUT, mutant; WT, wild-type.