Fig. 4: Motor neuron degeneration in spinal cord and abnormal NMJs.

a, b Confocal images and statistical analyses of choline ChAT-positive motor neurons (a) and GFAP⁺ cells (b) in ventral horn of the lumbar spinal cord from 12-month-old mice. White frame in (a) indicates the enlarged area. N = 3 mice; n = 15 slice, t-test. Scale bar in (a) whole spinal cord images: 200 μm; enlarged images: 100 μm. scale bar in (b): 25 μm. t-test. Data represent mean ± SEM. c RNAscope analysis of Pcdhα9 expression in 13-month wildtype mice spinal cord. CHAT: green; Pcdhα9: red. scale bar in low power images:100 μm; enlarged images: 10 μm. 3 biological repeats showed the same results. d Images of normally innervated and non-innervated NMJs and analyses of non-innervated NMJs. NMJs were stained with α-BTX (red) and neurofilament-200 (NF-200, green). White arrow indicated non-innervated AChR. Scale bar: 30 μm. n = 3 mice for each group. NMJs: n = 452 in WT, n = 736 in Mut, n = 620 in Del mice. one-way ANOVA. Data represent mean ± SEM. e Toluidine blue staining of sciatic nerve (13-month mice) and analyses of fibers with different diameters. Scale bar: 100 μm. 1 μm = 30 pixels. n = 6 slices from 3 mice, one-way ANOVA. Data represent mean ± SEM. f TDP-43 images and statistical analysis in 12-month WT and Mut mice. Percentage of motor neuron with nuclei clearance of TDP-43 was analyzed. n = 15 slices from 3 mice. t-test. Data represent mean ± SEM. g A schematic model of typical ALS pathology in Pcdha9 Mut and Del mice. Loss of motor neuron accompanied by activation of astrocyte in ventral spinal cord, skeletal muscle atrophy and NMJ denervation are detected in Pcdha9 Mut and Del mice. Those defects lead to motor dysfunction. Source data are provided as a source data file.