Fig 1: TGF-ß gene expression and signaling were downregulated in Sgcg-MRL skeletal muscle compared to Sgcg-D2 muscle.RNA sequencing was performed on quadriceps muscles from 16-week-old female mice in biological triplicate. Gene expression was normalized to Counts Per Million (CPM). (A) A comparison of Sgcg-MRL versus Sgcg-D2 transcriptomic profiles showed muscle development and differentiation genes to be highly enriched the Sgcg-MRL background (34). In contrast, immune response, extracellular matrix, and TGF-ß pathways were highly enriched in the Sgcg-D2 cohort. (B) Clustered heatmap shows reduction of extracellular matrix genes in Sgcg-MRL muscle. (C) Clustered heatmap shows reduction in TGF-ß pathway genes in Sgcg-MRL muscle. (D) Comparative log scale analysis showed substantially higher average expression of TGFB1 in the Sgcg-D2 cohort (WT-MRL 4.86, Sgcg-MRL 21.3, WT-D2 5.73, Sgcg-D2 55.9 CPM). (E) Immunoblotting of quadriceps muscles from Sgcg-D2 and Sgcg-MRL mice showed reduced phosphorylated SMAD3 (p-SMAD3) and total SMAD3 in Sgcg-MRL. (F) The ratio of p-SMAD3 to total SMAD3 was quantified and indicated TGF-ß signaling was decreased in the MRL background. Graphical quantification of mean ± SD. Two-way ANOVA was used to determine statistical significance in 4B, and Student’s t-test was used in 4D. * p<0.05, ** p<0.01, *** p<0.001, **** p<0.0001.