[A preliminary study on role of acid sphingomyelinase in receptor clustering induced by 50-Hz magnetic fields].
OBJECTIVE
To investigate the relationship among a 50-Hz MF-induced epidermal growth factor receptor (EGFR) clustering, acid sphingomyelinase (A-SMase) and ceramide (CER), and to explore the possible mechanism of receptor clustering.


METHODS
Human amnion (FL) cells were exposed to a 50-Hz sinusoidal magnetic field at 0.4 mT for 15 min with or without imipramine, a specific inhibitor of A-SMase and ceramide pretreatment. EGF treatment served as the positive control and DMSO treatment served as the solvent control. The EGFR was labeled with polyclonal anti-EGFR antibody and the clustering of EGFR was analyzed using immunofluorescence and confocal microscopy. The percentage of cells with EGFR clustering was counted and compared.


RESULTS
Both EGF treatment and 50-Hz MF exposure could induce EGFR clustering. However, the effect could be eliminated by imipramine pretreatment for 4 hours. When FL cells were incubated with ceramide following the imipramine pretreatment for 30 min, EGFR clustering induced by 50-Hz MF exposure could be recovered.


CONCLUSIONS
EGFR clustering induced by 50-Hz MF depends on A-SMase activity, and ceramide, as the hydrolyzate from A-SMase might participate in the process of EGFR clustering.
Li
Xing-wen
XW
Bioelectromeganetics Key Laboratory of Zhejiang Province, School of Medicine, Zhejiang University, Hangzhou 310058, China.
Lu
De-qiang
DQ
Jiang
Huai
H
Sun
Wen-jun
WJ
D000650:Amnion / Q000166:cytology; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism / Q000528:radiation effects; D002518:Ceramides / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism* / Q000528:radiation effects; D066246:ErbB Receptors / Q000378:metabolism*; D006801:Humans; D060526:Magnetic Fields / Q000009:adverse effects*; D013108:Sphingomyelin Phosphodiesterase / Q000378:metabolism / Q000502:physiology*
D002518:Ceramides; D066246:ErbB Receptors; D013108:Sphingomyelin Phosphodiesterase