Fig. 4: FABP3-overexpressing young muscle exhibits impaired muscle recovery after immobilization and early fatigue. | Nature Communications

Fig. 4: FABP3-overexpressing young muscle exhibits impaired muscle recovery after immobilization and early fatigue.

From: FABP3-mediated membrane lipid saturation alters fluidity and induces ER stress in skeletal muscle with aging

Fig. 4

a Scheme of the experimental procedures. TA muscles of young mice were transfected with HA-cherry-FABP3 or HA-cherry control plasmid, immobilized with a surgical staple 5 days after transfection, and allowed to recover (remobilization, n = 5) after 5-day immobilization (n = 5). b TA muscle mass was measured 5 days after immobilization and 5 days after remobilization. Changes in muscle mass were expressed as percentage of control. c Representative images of the transfected myofibers (red). (n = 5 per group). Scale bars, 100 μm. d Frequency histograms of the cross-sectional area (left) of HA-cherry-FABP3- or HA-cherry control plasmid-transfected muscle fibers 5 days after remobilization. Box plot representing the mean cross-sectional areas (right) of transfected muscle fibers. Box represent the 25th–75th percentiles of the data; whiskers show the min and max range of the data; horizontal lines indicate the median value. e Immunoblot analysis of PERK and eIF2α phosphorylation, and puromycin incorporation in FABP3-overexpressing and control TA muscles after remobilization. Five days after remobilization, mice were injected intraperitoneally with puromycin. TA muscles were harvested 30 min post-injection (n = 3 mice per group). f–i Muscle forces were measured in intact HA-cherry FABP3 or HA-cherry control plasmid-transfected TA muscles mounted on a force transducer. The maximum twitch force (f) at supramaximal voltage, 100 V for 1 ms. Frequency dependence (at 30–200 Hz, 100 V, 500 ms) of average tetanic force (g). Tetanic force traces (h) at 200 Hz for 500 ms (n = 7 mice per group). Fatigue index (i) was measured at 1 Hz and 100 V for 10 min. Generated force was recorded and expressed as a percentage of the initial force (left). Insert represents area under curve (AUC) (right) (n = 7 mice per group). Data are presented as means ± S.E.M. Two way ANOVA withBonferroni’s post hoc test was used (left in i) and two-tailed unpaired Student’s t-test was used (b, d, right in i). Source data are provided as a Source Data file.

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