The Study Of The Clustering Of EGF Receptor Induced By 50Hz Weak Magnetic Field

Extremely low frequency Magnetic fields (ELF-MF) of 50Hz with a strength of 0.4mT have been evidenced to induce clustering of Epidermal Growth Factor Receptor (EGFR) on Chinese Hamster Lung (CHL) cell membranes independent to EGF binding, an effect similar to the EGFR oligomerization triggered by binding of EGF to the receptor, an effect dependent to the exposure time of MF and an effect which will activate the EGFR pathway. By using atomic force microscope (AFM), transmission electron microscope (TEM), and con-focal laser scanning fluorescent microscope, the effects of ELF-MF on the clustering of purified receptors, and of the receptors in CHL cell membrane have investigated.Results from AFM indicated that 5ug/ml purified EGFR exposed to MF for 30min were induced doubled, tripled and even higher degree protein clustering in 2 dimensions. The average height of apparent clusters increase from 1.42±0.18 nm (sham) to 3.08±0.38 nm (exposed) and the average half-width from 21.7+2.2nm to 33.0+4.0nm. A similar effect of 2-D increase in cluster sizes was also observed by TEM with the average diameter increased from 11.63±l.llnm to 19.88±2.53nm. Furthermore, the clustering was time-dependent with a saturation time as 90 minutes. The treatments of purified EGFR by reduced glutathiol (GSH) did not affect the clustering in a statistic level, and the EGF-EGFR binding ability was not affected significantly by the interaction of the ELF-MF, but PD153035 (PD), an EGFR specific tyrosine kinase inhibitor, inhibited the ELF-MF-induced clustering of EGFR either of the purified proteins or of that in the cell membranes.These results indicated that the ELF-MF induced EGFR clustering by interfering directly with EGFR and suggested that the clustering was due to the interaction of the field to the cytoplasmic kinase domain. In conclusion, the membrane receptor was also one possible interaction site of ELF-MF.