Fig. 4.

Sustained mTORC1 activation alters endplate maintenance and abrogates AChR turnover. a Fluorescent images of TA innervated and denervated (21d), control (Ctrl) and TSCmKO muscles showing NMJ regions stained with α-bungarotoxin (Btx, red) and antibodies against neurofilament and synaptophysin (NF/Synapt, green). Representative of 6 independent muscles per group. Arrows point to degenerated endplates. Scale bar, 50 µm. b Fluorescent images of TA denervated control and TSCmKO muscles stained with α-bungarotoxin (Btx). High magnification pictures of the insets (lower panel) show ectopic plaque-like AChR clusters in TSCmKO muscle. Representative of 6 independent muscles per group. Scale bar, 100 (top) and 5 (inset) µm. c, d Number of fragments per endplate (c) and proportion of degenerated endplate (d) in TA control and TSCmKO (TSC) muscles after 14 and 21 days of denervation (De). c, n = 8 (In) and 4 (De) Ctrl, 6 (In) and 3 (De) TSCmKO muscles; d, n = 4 (Ctrl, 14d) and 3 (all other groups) independent muscles. e Fluorescent images of “old” (green) and “new” (red) AChRs in control and TSCmKO muscles (6 TA and 3 EDL muscles per genotype) in innervated muscle and after 2 weeks of denervation. Scale bar, 50 µm. f, g Quantification of AChR turnover (f, EDL muscle) and of endocytosed vesicles containing old or new AChRs (g) in innervated (In) and denervated (De) muscles from control and TSCmKO mice. n = 3 muscles per group. All values are mean ± s.e.m.; two-way ANOVA with Tukey’s post-hoc test, *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001. Source Data are provided in the Source Data File