Exposure of murine cells to pulsed electromagnetic fields rapidly activates the mTOR signaling pathway.
Murine pre-osteoblasts and fibroblast cell lines were used to determine the effect of pulsed electromagnetic field (PEMF) exposure on the production of autocrine growth factors and the activation of early signal transduction pathways. Exposure of pre-osteoblast cells to PEMF minimally increased the amount of secreted TGF-beta after 1 day, but had no significant effects thereafter. PEMF exposure of pre-osteoblast cells also had no effect on the amount of prostaglandin E(2) in the conditioned medium. Exposure of both pre-osteoblasts and fibroblasts to PEMF rapidly activated the mTOR signaling pathway, as evidenced by increased phosphorylation of mTOR, p70 S6 kinase, and the ribosomal protein S6. Inhibition of PI3-kinase activity with the chemical inhibitor LY294002 blocked PEMF-dependent activation of mTOR in both the pre-osteoblast and fibroblast cell lines. These findings suggest that PEMF exposure might function in a manner analogous to soluble growth factors by activating a unique set of signaling pathways, inclusive of the PI-3 kinase/mTOR pathway.
Patterson
Thomas E
TE
Department of Cell Biology, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA.
Sakai
Yoshitada
Y
Grabiner
Mark D
MD
Ibiwoye
Michael
M
Midura
Ronald J
RJ
Zborowski
Maciej
M
Wolfman
Alan
A
D000818:Animals; D002460:Cell Line; D002867:Chromones / Q000494:pharmacology; D015232:Dinoprostone / Q000378:metabolism; D004574:Electromagnetic Fields; D005347:Fibroblasts; D051379:Mice; D009025:Morpholines / Q000494:pharmacology; D010006:Osteoblasts; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D011494:Protein Kinases / Q000528:radiation effects*; D038601:Ribosomal Protein S6 / Q000378:metabolism; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism; D015398:Signal Transduction / Q000528:radiation effects*; D058570:TOR Serine-Threonine Kinases; D016212:Transforming Growth Factor beta / Q000378:metabolism
D002867:Chromones; D015232:Dinoprostone; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D011494:Protein Kinases; D038601:Ribosomal Protein S6; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D058570:TOR Serine-Threonine Kinases; D016212:Transforming Growth Factor beta; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C546843:mTOR protein, mouse