Figure 1. Nox4 mediates myocardial Nrf2 activation and is essential in the acute response to exercise.

(A) Changes in myocardial Nox4 mRNA and protein levels after acute moderate exercise (Ex) compared to sedentary controls (Sed). *p<0.05, **p<0.01, 2-tailed t-test (n = 4–6/group). (B) Exercise capacity of Nox4-null mice (Nox4KO) and littermate wild-types (WT) measured by maximal running distance and running time. **p<0.01, 2-tailed t-test (n = 5–8/group). (C) Ratio of glutathione/glutathione disulfide (GSH/GSSG) in Nox4KO and WT mouse hearts before (Sed) and after exercise (Ex). n = 6–9/group. (D) Protein levels of 4-hydroxynonenal (4-HNE) adducts in the heart. n = 3–4/group. (E and F) Protein and mRNA levels of major Nrf2 targets. n = 3–6/group *p<0.05, **p<0.01 vs respective sedentary controls (Sed); #p<0.05, ##p<0.01 vs WT/Ex, 1-way ANOVA followed by Tukey post hoc analysis. CAT: catalase, GSTA2: glutathione S-transferase A2, GCLC: glutamate cysteine ligase catalytic subunit, TXNRD1: thioredoxin reductase 1.

Figure 1—figure supplement 1. Full images of Western blots in Figure 1.

Figure 1—figure supplement 2. Myocardial Nox2 is unchanged during acute exercise.

Protein levels of total Nox2 (A) and p47^phox in membrane fraction (B) in normal mouse hearts after acute exercise (Ex). GAPDH and cadherin were used as cytosolic and membrane protein marker respectively. Sed: sedentary control, T: total heart tissue lysate, Mem: membrane fraction, Cyt: cytosolic protein. n.s: no significance. n = 3/group.

Figure 1—figure supplement 3. Quantification of Western blots in Figure 1E.

Protein levels of Nrf2 and its main targets in the hearts of Nox4KO and WT mice before (Sed) and after exercise (Ex). *p<0.05, **p<0.01 vs respective sedentary control. #p<0.05, ##p<0.01 vs WT/Ex, 1-way ANOVA followed by Tukey post hoc analysis (n = 4–6/group). GSTA2: glutathione S-transferase A2, GCLC: glutamate cysteine ligase catalytic subunit.