Plaat1 deficiency reduces cardiac cardiolipin content and impairs exercise tolerance

Figures

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  Fig. 1. Male and female mouse growth curves, food intakes, tissue weights, and survival. Body weights were monitored from 4 to 20 weeks of age in male (A) and female (D) mice (n = 3–5). Seven-day average food intakes were assessed (n = 4–5) (B, E). Weight-normalized organ and tissue weights of male (n = 5–7) (C) and female (n = 5–12) (F) Plaat1−/− mice and their control Wt littermates. Kaplan–Meier survival curves from weaning until 30 months of age were recorded for male (G) and female (H) mice. Data are means ± SEM. Food intakes, and organ and tissue masses were compared by Student’s t test; survival curves were compared using Chi-Square test. ∗P < 0.05, ∗∗P < 0.01.

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  Fig. 2. Plaat1 deficiency alters the concentration and composition of cardiac cardiolipin. Cardiolipin (CL) was isolated from hearts of male and female Wt and Plaat1−/− mice, as well as from male Tafazzin−/Δ mice for comparison, and the fatty acyl content (A, B) was analyzed by gas chromatography. The relative mass percentage (wt/wt%) of major fatty acyl species in cardiac cardiolipin is shown for male (C) and female (D) mice. Data are means ± S.E.M; n = 4–5. ∗P < 0.05, ∗∗P < 0.01, ∗∗∗P < 0.001, ∗∗∗∗P < 0.0001.

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  Fig. 3. Mitochondrial and electron transport chain protein expression and fibrosis and inflammation gene expression in cardiac tissue. Representative immunoblots from male (A, left hand panel) and female (H, left hand panel) wild-type (Wt) and Plaat1−/− (Ko) mouse hearts, along with images of total protein loading (A, H, right hand panels). Quantitation of band densities for NDUFS1 (B, I), SDHA (C, J), UQCRFS1 (D, K), COX IV (E, L), HSP60 (F, M), and TOM20 (G, N) are shown. Results are shown normalized to total protein per lane (A, H right hand panel). Expression of genes involved in inflammation (Ifnα, Ifnβ, Tnfα, Il1b, Il6) and fibrosis (Fn, Col1a1, Col3a1) in male (O) and female (P) hearts. Data are means ± S.E.M (n = 4–5), and comparisons were performed using Student’s t test. ∗P < 0.05, ∗∗P < 0.01.

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  Fig. 4. Respiratory gas exchange and energy expenditure. Whole-body VO2 (A, D), VCO2 (B, E), and TEE (C, F) was determined over a 24-h period in male and female Plaat1−/− mice and their Wt littermates. Line graphs show average measures recorded at 28-min intervals, with the dark period denoted by a shaded background and the light period denoted by an unshaded background. The corresponding bar graphs show calculated averages during the 24 h, light-, and dark-periods. Data are means ± SEM, (n = 6); Statistical comparisons were made by Student’s t test. ∗P < 0.05, ∗∗P < 0.01.

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  Fig. 5. RER measures in male and female mice. RERs were calculated for male (A) and female (B) mice and are shown in upper line graphs as average measures assessed at 28-min intervals over 24 h, with the dark photoperiod denoted by shaded background, and the light photoperiod denoted by the unshaded background. Bar graphs depicting 24 h, dark-period, and light-period averages are also shown. Data are means ± SEM (n = 6).

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  Fig. 6. Voluntary activity. Sums of infrared (IR) beam interruptions were recorded at 28 min intervals over a 24 h period for male and female Plaat1−/− and littermate Wt mice resulting from locomotion (A, D), ambulation (B, E), and rearing (C, F). Movement in the dark period is denoted by shaded background, while movement in the light period is denoted by an unshaded background. The corresponding bar graphs show total sums of IR beam interruptions during the 24 h period, 12 h dark period, and 12 h light period. Data are means ± SEM (n = 5–6). ∗P < 0.05.

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  Fig. 7. Exercise capacity. Using a treadmill test, the distance that male and female mice were able to run until exhaustion (A, E), the time at exhaustion (B, F), the average speed over the test period (C, G), and the maximum speed reached at exhaustion (D, H) were recorded. Data are means ± SEM (n = 11). ∗P < 0.05, ∗∗P < 0.01, ∗∗∗P < 0.001.