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Exposure of murine cells to pulsed electromagnetic fields rapidly activates the mTOR signaling pathway

Thomas E Patterson1, Yoshitada Sakai, Mark D Grabiner

  • 1Department of Cell Biology, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA.

Bioelectromagnetics
|May 23, 2006
PubMed

Insights

Pulsed electromagnetic field (PEMF) exposure rapidly activates the mTOR signaling pathway in pre-osteoblasts and fibroblasts. This activation, mediated by PI3-kinase, suggests PEMF may mimic growth factors.

Area of Science:

  • Cell Biology
  • Biophysics
  • Biochemistry

Background:

  • Pulsed electromagnetic field (PEMF) therapy is explored for various biological effects.
  • Understanding PEMF's impact on cellular signaling is crucial for therapeutic applications.
  • Autocrine growth factors and signal transduction pathways are key regulators of cellular processes.

Purpose of the Study:

  • To investigate the effect of PEMF on autocrine growth factor production in murine pre-osteoblasts.
  • To determine PEMF's influence on early signal transduction pathways in pre-osteoblasts and fibroblasts.
  • To elucidate the specific signaling cascade involved in PEMF-induced cellular responses.

Main Methods:

  • Murine pre-osteoblast and fibroblast cell lines were utilized.
  • Cells were exposed to PEMF, and conditioned media were analyzed for TGF-beta and prostaglandin E(2).
  • Western blotting was employed to assess the phosphorylation status of mTOR, p70 S6 kinase, and ribosomal protein S6.
  • The PI3-kinase inhibitor LY294002 was used to investigate pathway dependency.

Main Results:

  • PEMF exposure minimally increased TGF-beta secretion in pre-osteoblasts on day 1, with no sustained effect.
  • PEMF did not significantly alter prostaglandin E(2) levels in pre-osteoblasts.
  • Rapid and significant activation of the mTOR signaling pathway (increased phosphorylation of mTOR, p70 S6K, S6) was observed in both cell types upon PEMF exposure.
  • Inhibition of PI3-kinase activity abolished PEMF-induced mTOR activation.

Conclusions:

  • PEMF exposure activates the PI3-kinase/mTOR signaling pathway in pre-osteoblasts and fibroblasts.
  • This activation occurs rapidly and is dependent on PI3-kinase activity.
  • PEMF may exert its biological effects by activating signaling pathways, potentially mimicking soluble growth factors.

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