Fig 2: PrPC deficiency causes the defect in muscle regenerative capacity. (a) Schematic diagram of mouse treatment and grouping (By Figdraw, UAYYR9d9d0). (b) Tibialis anterior muscle contrast image, tibialis anterior muscle weight, and protein levels were shown at 7 and 28 days after cardiotoxin injection (n = 5). (c) Muscle regeneration capacity was measured in the tibialis anterior muscles of WT and KO mice at the indicated times after cardiotoxin injection by H&E staining; a representative data is shown (n = 3). (d) The expression levels of PrPC, SIRT‐1, PGC‐1α, VDAC‐1, Pax‐7, MyoD and MyoG were evaluated in the tibialis anterior of the mice at the indicated times after cardiotoxin injection by western blotting (n = 3, a representative result image is shown in Figure S3). (e) The expression levels of PPARγ, Catalase and GPx‐4 were evaluated in the tibialis anterior of the mice at the indicated times after cardiotoxin injection by western blotting: A representative data is shown (n = 5). (f) The expression levels of Pax‐7/β‐galactosidase and Pax‐7/p16 were evaluated in the tibialis anterior of the mice at 28 days after cardiotoxin injection by immunofluorescence; a representative data is shown (n = 3). Data are presented as mean ± SD. Data was analysed by one‐way ANOVA or two‐sided unpaired Student's t tests (* p < 0.05; ** p < 0.01; *** p < 0.001; ns, not significant, p > 0.05).

Fig 3: PrPC expression becomes active during myoblast differentiation. (a) Schematic diagram of C2C12 cell differentiation and grouping (By Figdraw, UAYYR9d9d0). (b,c) The expression levels of MyoD/PrPC (b) and MyoG/PrPC (c) were visualized at the indicated times during myoblast differentiation by immunofluorescence; a representative result from three independent experiments is shown (technical replicates). (d) The expression levels of PrPC, Pax7, MyoD and MyoG proteins were measured at 5 days post‐incubation of C2C12 cells under differentiation medium by the analysis of western blotting (upper panel). Immunofluorescence images of PrPC and MyoG protein at 5 days post‐incubation of C2C12 cells under differentiation medium (lower panel); a representative result from three independent experiments is shown (technical replicates). Data are presented as mean ± SD. Data was analysed by two‐sided unpaired Student's t tests (* p < 0.05; ** p < 0.01; *** p < 0.001; ns, not significant, p > 0.05).

Fig 4: PrPC deficiency causes SC senescence. (a) The expression levels of Pax‐7/β‐galactosidase and Pax‐7/p16 were measured in the tibialis anterior muscles of young and old WT and KO mice by immunofluorescence; a representative data is shown (n = 3). (b) The expression levels of β‐galactosidase and p16 were evaluated in the tibialis anterior by immunofluorescence (n = 3). Data are presented as mean ± SD. Data was analysed by one‐way ANOVA or two‐sided unpaired Student's t tests (* p < 0.05; ** p < 0.01; *** p < 0.001; ns, not significant, p > 0.05).

Fig 5: PrPC deficiency disturbs the homeostasis of mitochondria by modulating mitophagy and mitochondrial biogenesis. (a) Mitochondrial images were measured in the extensor digitorum longus muscles of young and old WT and KO mice by analysis of TEM. (b) The expression levels of VDAC‐1 and Parkin were visualized in the tibialis anterior muscles of the mice using immunofluorescence; a representative result from three independent experiments is shown. (c) The expression levels of PINK‐1, Parkin and VDAC‐1 were assessed in the gastrocnemius muscles of WT and KO mice by western blotting; a representative data is shown (n = 6). (d) Protein expression levels of SIRT‐1, PGC‐1α and OXPHOS (NADH‐UO, SDHB, COX‐1 and ATPsyn) in gastrocnemius muscle were shown by analysis of western blotting; a representative data is shown (n = 6). Data are presented as mean ± SD. Data was analysed by one‐way ANOVA or two‐sided unpaired Student's t tests (* p < 0.05; ** p < 0.01; *** p < 0.001; ns, not significant, p > 0.05).