Abstract
Dexamethasone (DEX), a synthetic glucocorticoid, causes skeletal muscle atrophy. This study examined the protective effects of Pyropia yezoensis peptide (PYP15) against DEX-induced myotube atrophy and its association with insulin-like growth factor-I (IGF-I) and the Akt/mammalian target of rapamycin (mTOR)-forkhead box O (FoxO) signaling pathway. To elucidate the molecular mechanisms underlying the effects of PYP15 on DEX-induced myotube atrophy, C2C12 myotubes were treated for 24 h with 100 μM DEX in the presence or absence of 500 ng/mL PYP15. Cell viability assays revealed no PYP15 toxicity in C2C12 myotubes. PYP15 activated the insulin-like growth factor-I receptor (IGF-IR) and Akt-mTORC1 signaling pathway in DEX-induced myotube atrophy. In addition, PYP15 markedly downregulated the nuclear translocation of transcription factors FoxO1 and FoxO3a, and inhibited 20S proteasome activity. Furthermore, PYP15 inhibited the autophagy-lysosomal pathway in DEX-stimulated myotube atrophy. Our findings suggest that PYP15 treatment protected against myotube atrophy by regulating IGF-I and the Akt-mTORC1-FoxO signaling pathway in skeletal muscle. Therefore, PYP15 treatment appears to exert protective effects against skeletal muscle atrophy.
Highlights
Bioactive peptides are generally composed of between three and 20 amino acid residues, and their activity is based on their amino acid composition and sequence [1]
These findings suggest that activation of the ubiquitin-proteasome and autophagy-lysosomal systems in skeletal muscle atrophy induced by GC exposure may be mediated by the activation of
The present study was undertaken to investigate whether the protective effects of P. yezoensis peptide (PYP15) against DEX-induced myotube atrophy are associated with the proteolytic system, and whether this is regulated by the insulin-like growth factor-I (IGF-I)-mediated Akt-mammalian target of rapamycin (mTOR)
Summary
Bioactive peptides are generally composed of between three and 20 amino acid residues, and their activity is based on their amino acid composition and sequence [1]. The short chains of amino acids are in an inactive state within the sequence of the parent protein molecule, but can be liberated by proteolytic enzymes during gastrointestinal digestion or food processing and fermentation processes [2]. These peptides exhibit various physiological activities, such as anti-hypertensive [3], anti-oxidant [4,5,6], and anti-inflammatory effects [7,8] depending on their structural, sequential, and constitutive characteristics. Previous studies have reported that peptides synthesized from P. yezoensis reduced the inflammatory stress induced. Weight loss, osteoporosis, depression, hypertension, and skeletal muscle atrophy [18]
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