Autocrine phosphorylation of p70S6k in response to acute stretch in myotubes

Keith Baar, Carol E. Torgan, William E. Kraus, Karyn Esser

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


Phosphorylation of 70-KDa S6 kinase (p70S6k) is correlated with in vivo skeletal muscle hypertrophy. Experiments tested whether mechanical stretch is sufficient to increase p70S6k phosphorylation in skeletal myotubes. Immediately following stretch, there was a small increase in p70S6k phosphorylation (63.2 ± 8.5%) with maximal phosphorylation at 3 h (129.5 ± 22.2%) and it remained elevated through 24 h (46.0 ± I7.2%). To test whether an autocrine mechanism is involved, unstretched myotubes were incubated with medium from the stretch group for 10 min. Conditioned medium resulted in the phosphorylation of p70S6k in unstretched myotubes (92.8 ± 28.9%) to levels cornparable to the 3-h stretch group. These data indicate that p70S6k is phosphorylated in stretched myotubes via a mechanism that most likely involves an autocrine signaling pathway.

Original languageEnglish (US)
Pages (from-to)76-80
Number of pages5
JournalMolecular Cell Biology Research Communications
Issue number2
StatePublished - 2000
Externally publishedYes


  • Autocrine
  • Cell stretch
  • Muscle hypertrophy
  • P70
  • Signaling

ASJC Scopus subject areas

  • Molecular Biology


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