Fig. 1: Exercise induces CLCF1 expression in skeletal muscle.

A Volcano plots showing differentially expressed genes (DEGs) encoding secretory proteins in skeletal muscles of young and old adults before and after 12 weeks of progressive resistance training. B Expression levels of genes commonly found in three DEG groups (yBase, n = 15; y1st, n = 16; yFinal, n = 16; oBase, n = 12; o1st, n = 12; oFinal, n = 12, p = 0.0278, 0.0453, 0.0223 (CLCF1); 0.0011, 0.0379 (LCAT); 0.005, 0.0299, 0.014, 0.0095 (CCL2); 2.00e-7, 0.0002 (PRSS50): young and old adults). C Clcf1 expression in C2C12 myotubes treated with AICAR (1 mM, 24 h; n = 3, p = 0.001; biological replicates). D Left: Immunoblot analysis of C2C12 myotubes treated with AICAR. Right: Quantification by densitometry analysis (n = 4, p = 0.0026). E Clcf1 expression in C2C12 myotubes subjected to electrical pulse contraction (EPS; n = 6, p = 0.0015; biological replicates). F Left: Immunoblot of C2C12 myotubes after EPS. Right: Quantification of western blots by densitometry analysis (n = 3, p = 0.046). G mRNA expression of Clcf1 in skeletal muscles following treadmill running (3 mo, male, created in BioRender.com) (n = 4; p = 0.0062, 0.047, 0.018). H Plasma concentration of CLCF1 measured 30, 60, or 90 min after treadmill exercise in young (3 mo, male) and aged (24 mo, male) mice (n = 4, p = 0.026, 0.038, 1.3e-4), Box plots show the median (center line), interquartile range (25th–75th percentiles), and the full data range (minimum to maximum, shown as whiskers). I Plasma CLCF1 concentration in young (3 mo, male), middle-aged (8 mo, male), and aged (18 mo, male) mice (n = 10; p = 3.4.e-4, 1e-6, 0.041). Data are presented as means ± s.e.m.; one-way ANOVA with post hoc Tukey’s multiple comparison test (B, I); two-tailed unpaired Student’s t-test (C–G); two-way ANOVA with post hoc Tukey’s multiple comparison test (H). *p < 0.05, **p < 0.005 and ***p < 0.001. Source data are provided as a Source Data file.