title: Acid sphingomyelinase mediates 50-Hz magnetic field-induced EGF receptor clustering on lipid raft.
abstract: Previously, we found that exposure to a 50-Hz magnetic field (MF) could induce epidermal growth factor receptor (EGFR) clustering and phosphorylation on cell surface. In order to explore the possible mechanisms, the roles of acid sphingomyelinase (ASMase) and lipid raft in MF-induced EGFR clustering were investigated in the present study. Human amnion epithelial (FL) cells were exposed to a 50-Hz MF at 0.4 mT for different durations. Intracellular ASMase activity was detected using the Amplex® Red Sphingomyelinase Assay Kit. EGFR clustering, ASMase, and lipid rafts on cell membrane were analyzed using confocal microscopy after indirect immunofluorescence staining. Results showed that disturbing lipid rafts with nystatin could inhibit MF-induced EGFR clustering, indicating that it was dependent on intact lipid raft. Exposure of FL cells to MF significantly enhanced ASMase activity and induced ASMase translocation to membrane that co-localized with lipid rafts. Treatment with imipramine, an ASMase inhibitor, inhibited the MF-induced EGFR clustering. This inhibitory effect could be blocked by the addition of C2-ceramide in the culture medium. It suggested that ASMase mediated the 50-Hz MF-induced EGFR clustering via ceramide which was produced from hydrolyzation on lipid rafts.
authors.affiliation: a Bioelectromagnetics Key Laboratory, Zhejiang University School of Medicine , Hangzhou , Zhejiang , People's Republic of China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
authors.affiliation: a Bioelectromagnetics Key Laboratory, Zhejiang University School of Medicine , Hangzhou , Zhejiang , People's Republic of China.|b Cixi Sanitary Supervision Station , Cixi , People's Republic of China.
authors.forename: Xingwen
authors.initials: X
authors.lastname: Li
authors.affiliation: a Bioelectromagnetics Key Laboratory, Zhejiang University School of Medicine , Hangzhou , Zhejiang , People's Republic of China.|c The Second Affiliated Hospital, Zhejiang University School of Medicine , Hangzhou , Zhejiang , People's Republic of China.
authors.forename: Liyuan
authors.initials: L
authors.lastname: Sun
authors.affiliation: a Bioelectromagnetics Key Laboratory, Zhejiang University School of Medicine , Hangzhou , Zhejiang , People's Republic of China.
authors.forename: Baihuan
authors.initials: B
authors.lastname: Feng
authors.affiliation: a Bioelectromagnetics Key Laboratory, Zhejiang University School of Medicine , Hangzhou , Zhejiang , People's Republic of China.|d Institute of Environmental Medicine, Zhejiang University School of Medicine , Hangzhou , Zhejiang , People's Republic of China.
authors.forename: Wenjun
authors.initials: W
authors.lastname: Sun
mesh_terms: D000650:Amnion / Q000166:cytology / Q000528:radiation effects; D004847:Epithelial Cells / Q000201:enzymology / Q000528:radiation effects; D066246:ErbB Receptors / Q000378:metabolism*; D006801:Humans; D007099:Imipramine; D060526:Magnetic Fields; D021962:Membrane Microdomains / Q000378:metabolism* / Q000528:radiation effects; D010766:Phosphorylation; D013108:Sphingomyelin Phosphodiesterase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D013110:Sphingosine / Q000008:administration & dosage / Q000031:analogs & derivatives
chemical_list: C064769:N-acetylsphingosine; D066246:ErbB Receptors; C112980:acid sphingomyelinase-1; D013108:Sphingomyelin Phosphodiesterase; D013110:Sphingosine; D007099:Imipramine
keywords: Acid sphingomyelinase; clustering; epidermal growth factor receptor; extremely low-frequency magnetic field; lipid raft