Simulated microgravity inhibits C2C12 myogenesis via phospholipase D2-induced Akt/FOXO1 regulation

• Published in: Scientific reports Vol. 9; no. 1; pp. 14910 - 13
• Main Authors: Baek, Mi-Ock, Ahn, Chi Bum, Cho, Hye-Jeong, Choi, Ji-Young, Son, Kuk Hui, Yoon, Mee-Sup
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 17.10.2019; Nature Publishing Group
• Subjects: 13; 13/106; 13/89; 13/95; 14; 14/63; 631/136/142; 631/80/83/2359; 704/172/4081; 82; 96; 96/1; AKT protein; Animals; Cell Culture Techniques - methods; Cell Differentiation - physiology; Cell Line; Forkhead Box Protein O1 - metabolism; FOXO1 protein; Gravity; Growth rate; Humanities and Social Sciences; Mechanical unloading; Mechanistic Target of Rapamycin Complex 2 - metabolism; Mice; Microgravity; mRNA; multidisciplinary; Muscle Development - physiology; Musculoskeletal system; Myoblasts; Myoblasts - physiology; Myogenesis; Phospholipase D; Phospholipase D - metabolism; Phospholipase D2; Phosphorylation; Posture; Proto-Oncogene Proteins c-akt - metabolism; Rapamycin; Science; Science (multidisciplinary); Signal Transduction - physiology; Skeletal muscle; TOR protein; Weightlessness Simulation - adverse effects; Weightlessness Simulation - methods
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-019-51410-7

The skeletal muscle system has evolved to maintain body posture against a constant gravitational load. Mammalian target of rapamycin (mTOR) regulates the mechanically induced increase in the skeletal muscle mass. In the present study, we investigated mTOR pathway in C2C12 myoblasts in a model of mechanical unloading by creating a simulated microgravity (SM) using 3 D clinorotation. SM decreased the phosphorylation of Akt at Ser 473, which was mediated by mTOR complex 2 (mTORC2), in C2C12 myoblasts, leading to a decrease in the cell growth rate. Subsequently, SM inhibited C2C12 myogenesis in an Akt-dependent manner. In addition, SM increased the phospholipase D (PLD) activity by enhancing PLD2 expression, resulting in the dissociation of mSIN1 from the mTORC2, followed by decrease in the phosphorylation of Akt at Ser 473, and FOXO1 at Ser 256 in C2C12 myoblasts. Exposure to SM decreased the autophagic flux of C2C12 myoblasts by regulation of mRNA level of autophagic genes in a PLD2 and FOXO1-dependent manner, subsequently, resulting in a decrease in the C2C12 myogenesis. In conclusion, by analyzing the molecular signature of C2C12 myogenesis using SM, we suggest that the regulatory axis of the PLD2 induced Akt/FOXO1, is critical for C2C12 myogenesis.