Aim
To explore the effects and mechanisms of different concentrations of uric acid on skeletal muscle cells.
Methods
C2C12 myoblasts were differentiated into myotubes and then exposed to a medium containing uric acid (0 μM, 200 μM, 400 μM, 600 μM, 800 μM, 1000 μM, 1200 μM, 1400 μM). The myotube diameters were observed under light microscopy; the expressions of myosin heavy chain (MyHC), autophagy‐related proteins (LC3BII/LC3BI, P62), cGAS, and p‐Sting/Sting proteins were analyzed using Western blotting or immunoprecipitation; and oxidative stress and mitochondrial damage were evaluated using ROS, mtDNA and JC‐1 assays. Cell viability was measured via CCK8 assay, and 1000‐μM uric acid was selected for follow‐up experiments. Furthermore, C2C12 myotubes were divided into a blank control group (Ctrl), a high‐uric‐acid group (HUA), and an HUA plus cGASn inhibitor group (HUA + RU.521). Then, the myotube diameter was observed, oxidative stress and mitochondrial damage were evaluated, and MyHC and autophagy‐related protein expressions were analysed.
Results
C2C12 myotubes cultured in 400‐μM uric acid medium had the greatest myotube diameter and the highest MyHC protein expression. At 1000‐μM uric acid, the diameter and MyHC protein expression were significantly decreased, LCB3II/LCB3I expression was notably increased, and the level of p62 protein expression was considerably decreased. RU.521 partially alleviated the HUA‐induced C2C12 myotubes changes.
Conclusions
Uric acid bidirectionally affected C2C12 myotubes: 400‐μΜ uric acid promoted myotube growth, while 1000‐μΜ uric acid triggered myotube atrophy with increased autophagy. Inhibiting cGAS‐Sting signaling attenuated HUA‐induced C2C12 myotube autophagy and atrophy. Geriatr Gerontol Int 2024; 24: 430–439.