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Fig. 3 | Skeletal Muscle

Fig. 3

From: Skeletal muscle interleukin 15 promotes CD8+ T-cell function and autoimmune myositis

Fig. 3

High concentration of IL-15 hyperagonist, but not IL-15, induces STAT5 signaling and atrophy in skeletal muscle cells. a Analysis of IL-15Rβ and γc expression on C2C12 myoblasts under the same condition of Fig. 2a. Data are representative of three independent experiments with similar results. b Expression of Il15rb and γ c mRNA in C2C12 and primary myotube. Samples were collected 24 h after cytokine treatment and analyzed by qPCR. Data are triplicates and representative of two independent experiments with similar results. c Immunoblotting of STAT5 phosphorylation in C2C12 myotubes after treating with IL-15 or IL-15 hyperagonist for 30 min. Quantification data of four independent experiments are shown below. d Anti-IL-15Rβ antibody diminished IL-15 hyperagonist-induced STAT5 phosphorylation in C2C12 myotubes. Myotubes were pretreated with anti-IL-15Rβ or isotype control antibody for 1 h and then treated with IL-15 hyperagonist for 30 min. Data are representative of two independent experiments with similar results. e Immunoblotting of STAT5 phosphorylation in C2C12 myotubes that were first stimulated with TNF-α and IFN-γ for 24 h and then treated with exogenous IL-15 or IL-15 hyperagonist for 30 min. Data are representative of two independent experiments with similar results. f Accumulation of myosin heavy chain (MyHC) in C2C12 myotubes treated with IL-15 (50 and 100 ng/ml), IL-15 hyperagonist (50 and 100 ng/ml), or vehicle (0 ng/ml). After 48 h, cells were immunostained with FITC-labeled anti-myosin antibody to evaluate the accumulation of MyHC. MyHC-positive area per microscopic field are shown in the right panel and represented as the percentages of con. Quantification data were pooled from three independent experiments. Each symbol represents the quantification data from one microscopic field. Scale bar = 500 μm. Data are mean ± SEM. *p < 0.05, **p < 0.01, ***p < 0.001

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