Fig. 8.

MyD88 promotes over load-induced myofiber hypertrophy in adult mice. a Twelve-week-old WT mice were subjected to sham or synergistic ablation surgery for 14d and the plantaris muscle was analyzed for the protein levels of MyD88 and unrelated protein GAPDH. b Twelve-week-old MyD88^f/f and MyD88^myoKO mice were subjected to sham or synergistic ablation surgery for 14d and the plantaris muscle was isolated and stained with H&E. Representative photomicrographs of H&E-stained plantaris muscle sections are presented here. Scale bar: 50 µm. c Quantification of average myofiber CSA in the H&E-stained sections of plantaris muscle. d Average number of myofibers in plantaris muscle of MyD88^f/f and MyD88^myoKO mice at 14d after synergistic ablation surgery. For c and d, N = 7 mice in each group. In a separate experiment, 12-week-old MyD88^f/f and MyD88^myoKO mice were subjected to sham or synergistic ablation surgery. After 2 days, the mice were given an intraperitoneal injection of EdU, and 12 days later plantaris muscles were collected, and muscle sections prepared were stained to detect EdU, laminin, and nuclei. e Representative photomicrographs after EdU, laminin, and DAPI staining are presented here. Arrows point to intrafiber EdU⁺ nuclei. Scale bar: 100 µm. f Quantification of percentage myofibers containing EdU⁺ nuclei in plantaris muscle of MyD88^f/f and MyD88^myoKO mice. N = 4 in each group. Error bars represent s.d. *p < 0.05 from corresponding sham-operated MyD88^f/f or MyD88^myoKO mice by unpaired t-test. ^# p < 0.05 from 14d-loaded muscle of MyD88^f/f mice by unpaired t-test