Extended Data Fig. 12: The LCA-TULP3-sirtuins-v-ATPase axis enhances muscle functions in aged mice.
From: Lithocholic acid binds TULP3 to activate sirtuins and AMPK to slow down ageing
a-d, V1E1-3KR improves muscle function in aged mice. WT or muscle-specific AMPKα knockout (α-MKO) mice with muscle-specific expression (induced by tamoxifen at 16 months old; see “mouse strains” section of the Methods section for the procedures for constructing this strain) of V1E1-3KR or wildtype V1E1 were subjected to analysis for AMPK activation (a), the ratios of mtDNA:nDNA (b), the mRNA and protein levels of the OXPHOS complex (c), and the OCR (d) in the gastrocnemius muscle. Results are shown as mean ± s.e.m.; n = 4 (b, c) or 5 (d) mice for each genotype/treatment, and P value by two-way ANOVA followed by Tukey’s test. e-g, V1E1-3KR elevates energy expenditure (EE) and respiratory quotient (RQ) in aged mice. Mice were treated as in a, followed by determination of EE (e). Data are shown as mean (left panel; at 5-min intervals during a 24-h course after normalization to the body weight (kg0.75)), or as box-and-whisker plots (right panel, in which the lower and upper bounds of the box represent the first and the third quartile scores, the centre line represents the median, and the lower and upper limits denote minimum and maximum scores, respectively; and the same hereafter for all box-and-whisker plots; n = 4 mice for each genotype/treatment, and P value by two-way ANOVA followed by Tukey’s test). See also respiratory quotient (RQ) and the ambulatory activity data generated in this experiment in f (data are shown as mean (at 5-min intervals during a 24-h course; n = 4 mice for each genotype), or box-and-whisker plots (n = 4 mice for each genotype, and P value by two-way ANOVA followed by Tukey’s test)), and the body composition data in g (mean ± s.e.m., n = 5 mice for each genotype, and P value by two-way ANOVA followed by Tukey’s test). h, i, j, TULP3-4G blocks CR-elevated mitochondrial content in muscle. The muscle-specific TULP3 knockout (TULP3-MKO) mice with re-introduced muscular expression of TULP3-4G or wildtype TULP3 (induced by tamoxifen at 16 months old; see validation data in i, and the procedures for constructing this strain in “mouse strains” section of the Methods section) were subjected to CR for 3.5 months, followed by determination of mtDNA:nDNA ratios (h). Results in h are shown as mean ± s.e.m., n = 6 mice for each genotype/treatment, and P value by two-way ANOVA followed by Tukey’s test. See also AMPK activation in the muscle of TULP3-4G-re-introduction mice after 3.5 months of CR (left panel), or 1 month of (2-hydroxypropyl)-β-cyclodextrin-coated LCA treatment (1 g/l in the drinking water; right panel) in j. Experiments in this figure were performed three times.
