Figure 1.

Reduced LRP4 level and MuSK phosphorylation in aged mice. A, Diagram of a hemi-diaphragm to illustrate SR and NSR. B, Enriched AChR mRNA (left) and protein (right) in SR. t₍₄₎ = 34.4, ***p = 4.2E-6 for Chrna; t₍₄₎ = 9.6, ***p = 0.00067 for Chrnd; t₍₄₎ = 6.78,*p = 0.019 for Ache; N = 3 mice per group, unpaired t test. C, Increased AChR-δ protein level in aged muscles. D, Quantification of data in C. t₍₄₎ = 5.5,*p = 0.021 for AChRδ. E, Reduced LRP4 protein level in aged muscles. F, Quantification of data in E. t₍₄₎ = 5.9, **p = 0.004. G, Reduced tyrosine-phosphorylation of MuSK in aged muscles. H, Quantification of p-MuSK over MuSK in G. t₍₄₎ = 4.7, *p = 0.019. C–H, SRs of diaphragms of indicated ages were homogenized and subjected to Western blotting. N = 3 mice per group, unpaired t test.