Fig. 4

Delivery of wild type MTM1 gene rescues myonuclear density and distribution defects in dogs with XLMTM. Dogs from a previous study were separated into the following groups (N = 3 per group): healthy controls, injected with saline; dogs expressing the p.N155K mutation in the MTM1 gene, injected with a saline solution (XLMTM group); and dogs expressing the MTM1 mutation but given 3 different doses of rAAV8-cMTM1 (AAVLow, AAVMid, AAVHigh). a Typical single myofibres from each group, stained for actin (rhodamine phalloidin; red) and nuclei (DAPI; green). Scale bar: 50 μm. b Proportion of muscle fibres containing internal or central nuclei. Each data point corresponds to the mean per animal. c Number of myonuclei per individual myofibre. d Myonuclei number was linearly related to fibre CSA for all the groups (P < 0.05). The regression lines were significantly more elevated for XLMTM and AAVLow dogs versus all other groups (P < 0.05). e Myonuclear domain volume per individual muscle fibres. f Myonuclear domain size was linearly related to fibre CSA for all the groups (P < 0.05). g Order score (g). Graphs showing shape quantifications for nuclei: projected area in the 2D (X–Y) plane, h and aspect ratio i. For c–g, data points correspond to individual muscle fibres. For h and i, individual data points correspond to individual nuclei. Column graphs show mean ± S.D. Scatter graphs show linear regression lines. Asterisks denote a significant difference compared with CTL (*P < 0.05; **P < 0.01; one-way ANOVA)