Involvement of PI3K/Akt/TOR pathway in stretch-induced hypertrophy of myotubes

Bibliographic Information

Title
Involvement of PI3K/Akt/TOR pathway in stretch-induced hypertrophy of myotubes
Other Title
  • 伸張刺激により引き起こされる筋管細胞肥大への PI3K/Akt/TOR 経路の関与
Author
笹井, 宣昌
Author
SASAI, NOBUAKI
University
NAGOYA University
Types of degree
博士(リハビリテーション療法学)
Grant ID
甲第8665号
Degree year
2010-03-25

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Description

Skeletal muscle cells are hypertrophied by mechanical stresses, but the underlying molecular mechanisms are not fully understood. Two signaling pathways, phosphatidylinositol 3-kinase (PI3K)/Akt to target of rapamycin (TOR) and extracellular signal-regulated kinase kinase (MEK) to extracellular signal-regulated kinase (ERK), have been proposed to be involved in muscle hypertrophy. In this study we examined the involvement of these pathways in primary cultures of chick skeletal myotubes subjected to passive cyclic stretching for 72 hours, a time that was sufficient to induce significant hypertrophy in our preparations. Hypertrophy was largely suppressed by wortmannin or rapamycin, inhibitors of PI3K or mTOR, respectively. Furthermore, phosphorylation of Akt was enhanced by stretching and suppressed by wortmannin. The MEK inhibitor, U0126, exerted a minimal influence on stretch-induced hypertrophy. We found that cyclic stretching of myotubes activates the PI3K/Akt/TOR pathway, resulting in muscle hypertrophy. The MEK/ERK pathway may contribute negatively to spontaneous hypert

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