MON-721 Crude Protein of Pyropia Yezoensis Protects Against Tumor Necrosis Factor-á-Induced Myotube Atrophy by Regulating the Mitogen-Activated Protein Kinase and Nuclear Factor-Kappab Signaling Pathways in C2C12 Myotubes

Proinflammatory cytokines induce ubiquitin-proteasome-dependent proteolysis by activating intracellular factors in skeletal muscle, leading to muscle atrophy. Therefore, we investigated the protective effect of Pyropia yezoensis crude protein (PYCP) on tumor necrosis factor (TNF)-α-induced muscle atrophy in vitro. Mouse skeletal muscle C2C12 myotubes were treated for 48 h with TNF-α (20 ng/mL) in the presence or absence of PYCP (25, 50, and 100 μg/mL). PYCP at concentrations up to 100 μg/mL did not affect cell viability. Exposure to TNF-α for 48 h significantly decreased the diameter of myotubes, which was increased by treatment with 25, 50, and 100 μg/mL PYCP. PYCP inhibited TNF-α-induced intracellular reactive oxygen species accumulation in C2C12 myotubes. In addition, PYCP significantly reduced the levels of phosphorylated p38 and JNK. Moreover, by inhibiting the degradation of inhibitor of kappaB-α, PYCP significantly suppressed the TNF-α-induced increased transcriptional activity and nuclear translocation of nuclear factor-kappaB (NF-κB). Furthermore, PYCP inhibited E3-ubiquitin ligases in TNF-α-treated C2C12 myotubes. In conclusion, PYCP ameliorated TNF-α-induced muscle atrophy by inhibiting the mitogen-activated protein kinase-mediated NF-κB pathway, indicating that it has therapeutic potential for related disorders.