In a previous study (Wu et al. 2014), the authors found that exposure to a 50 Hz magnetic field affected cell migration and the actin-cytoskeleton. If and how microtubules as another major component of the cytoskeleton are affected as well, should be investigated in this study.
Human amniotic epithelium cells (FL) and rat pheochromocytoma cells (PC12) were divided into the following groups: 1) MF: exposure to the magnetic field, 2) sham exposure, 3) EGF: EGF treatment (and sham exposure), 4) EGF + MF, 5) PD: treatment with EGFR tyrosine kinase (TK) inhibitor PD153035 (PD) (used to investigate involvement of EGFR signal pathway) (and sham exposure), 6) PD + MF, 7) PD + EGF. 8) NIF: treatment with L-type calcium channel inhibitor nifedipine (NIF) (used to investigate involvement of calcium signal pathway) (and sham exposure), 9) PD + NIF, 10) PD + NIF + MF, 11) PD + NIF + EGF.
Exposure duration: 30 minutes
|Exposure duration||30 minutes|
|magnetic flux density||0.4 mT||-||-||-||-|
The amount of microtubules was significantly reduced and focal adhesion was significantly increased in both cell lines in group 1 (magnetic field exposure) and group 3 (EGF treatment) compared to the sham exposure group (group 2). Clustering of the EGFR could be detected in both groups 1 and 3. These effects were strongly depending on the calcium signal pathway through the L-type calcium channel and elevation of the intracellular calcium level. The magnetic field-induced reorganization of the cytoskeleton network was mediated via phosphorylation of the signaling proteins in the EGFR and calcium signal pathways, including the important microtubule protein tau.
The authors conclude that exposure of cells to a 50 Hz magnetic field activates the microtubule-cytoskeleton in a way similar to EGF through a mechanism related to both EGFR and calcium signaling pathways.