Molecular and Cellular Biochemistry

, Volume 406, Issue 1–2, pp 285–292 | Cite as

Mechanical stretch activates mammalian target of rapamycin and AMP-activated protein kinase pathways in skeletal muscle cells

  • Naoya Nakai
  • Fuminori Kawano
  • Ken Nakata


Cellular protein synthesis is believed to be antagonistically regulated by mammalian target of rapamycin (mTOR) and AMP-activated protein kinase (AMPK) signaling pathways. In the present study, we examined the relationship between mTOR/p70 S6 kinase (p70S6K) and AMPK in response to mechanical stretch. C2C12 myoblasts were grown on a silicone elastomer chamber to confluence and further cultured in differentiation medium for 4 days to form multinucleated myotubes. Cells were subjected to 15 % cyclic uniaxial stretch for 4 h at a frequency of 1 Hz. Phosphorylation of p70S6K at threonine 389 and AMPK at threonine 172 of the catalytic α subunit were concomitantly increased by mechanical stretch. Stimulation of the mTOR pathway by adding leucine and insulin increased the phosphorylation of p70S6K without inactivation of AMPK. In contrast, addition of compound C, a pharmacological inhibitor of AMPK, increased the phosphorylation of p70S6K in stretched cells. Activation of AMPK by the addition of 5-amino-4-imidazolecarboxamide ribonucleoside reduced the phosphorylation of p70S6K in response to mechanical stretch. In conclusion, crosstalk between mTOR and AMPK signaling was not tightly regulated in response to physiological stimuli, such as mechanical stress and/or nutrients. However, pharmacological modulation of AMPK influenced the mTOR/p70S6K signaling pathway.


Mechanical stimulus Mammalian target of rapamycin AMP-activated protein kinase Protein synthesis 



This work was supported by a Grant-in-Aid for Scientific Research C (25350813 to N.N.) from the Japan Society for the Promotion of Science (JSPS), Japan.

Conflict of interest

The authors declare that there are no conflicts of interest.


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Copyright information

© Springer Science+Business Media New York 2015

Authors and Affiliations

  1. 1.Department of Health and Sports Sciences, Graduate School of MedicineOsaka UniversityToyonakaJapan
  2. 2.Department of Nutrition, School of Human CulturesUniversity of Shiga PrefectureHikoneJapan

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