Fig. 1

α-Klotho is increased in young muscle after injury, but the response is lost  with increased age. a−d Immunofluorescent imaging of α-Klotho and F-actin in skeletal muscle from uninjured young (UIY; 4–6 months) and old mice (UIO; 22–24 months) as well as 14 days post injury (dpi) in young (YI) and old (OI) mice. Scale: 50 µm. e Quantification of α-Klotho across the four comparison groups, UIY, UIO, YI, and OI. Experimental cohorts were performed in duplicate, n = 3/group/cohort. ****p < 0.0001. f ELISA analysis of serum obtained from UIY, UIO, YI, and OI mice (n = 8–11/group; ****p < 0.0001). g RT-qPCR analysis of α-Klotho in young and old muscles at 0 (control), 3, 7, and 14 dpi (n = 4/age/timepoint). h MSPCR analysis of young and old muscle at 0 (control), 3, 7, and 14 dpi (n = 4/age/timepoint). i ChIP analysis of DNMT3a in young and old muscle at 0 (control), 3, 7, and 14 dpi (n = 3-4/age/timepoint). j ChIP analysis of H3K9me2 in the Klotho promoter in young and old muscle at 0 (control), 3, 7, and 14 dpi (n = 4/age/timepoint) (*p < 0.05 compared to young, sex-matched uninjured muscles; #p < 0.05 indicates a significant difference between young and aged groups at the respective timepoint). e−g One-way ANOVA with Tukey’s post-hoc test. h−j Two-way ANOVA with Tukey’s post-hoc test. Data represented as mean ± SEM