Induction of stress proteins by electromagnetic fields in cultured HL-60 cells.
HL-60 cells in culture were exposed for 2 h to a sinusoidal 0.1 or 1 mT (1 or 10 Gauss) magnetic field at 60 Hz and pulse labeled after exposure with radioactive isotopes by incubation by using either [(35)S]methionine, [(3)H]leucine, or [(33)P]phosphate. The radioactive labels were incorporated into cellular proteins through synthesis or phosphorylation. Proteins were extracted from electrostatically sorted nuclei, and the heat shock/stress proteins (sp) were analyzed for synthesis and phosphorylation by two-dimensional polyacrylamide gel electrophoresis. In the control cultures (no exposure to the magnetic field), sp 72c (cognate form) was faintly observed. A 0.1 mT exposure did not show sp metabolism to be different from that of the controls; however, after a 1 mT exposure of the HL-60 cells, sp 70i (inducible form) was synthesized ([(35)S]methionine incorporation). Sp 90 was not synthesized at either field level, but was phosphorylated ([(33)P]phosphate incorporation) in the 1 mT exposure. Sp 27 (isoforms a and b) was induced after a 1 mT exposure as reflected by labeling with [(3)H]leucine. These sps were not detected after a 0.1 mT exposure. After a 1 mT exposure and labeling with [(33)P], sp 27 isoforms b and c were phosphorylated whereas isoform 'a' was not observed. Sps 70i, 72c, and 90 were identified by commercial sp antibodies. Likewise, polypeptides a, b, and c were verified as sp 27 isoforms by Western blotting. Statistical evaluation of sp areas and densities, determined from fluorographs by Western-blot analysis, revealed a significant increase in sps 90 and 27a after a 1 mT magnetic field exposure. The 1 mT magnetic field interacts at the cellular level to induce a variety of sp species. Bioelectromagnetics 20:347-357, 1999. Published 1999 Wiley-Liss, Inc.
Pipkin
J L
JL
National Center for Toxicological Research, Jefferson, Arkansas 72079, USA.
Hinson
W G
WG
Young
J F
JF
Rowland
K L
KL
Shaddock
J G
JG
Tolleson
W H
WH
Duffy
P H
PH
Casciano
D A
DA
D004574:Electromagnetic Fields / Q000009:adverse effects*; D015180:Electrophoresis, Gel, Two-Dimensional; D018922:HL-60 Cells; D055551:HSP27 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis / Q000302:isolation & purification; D050884:HSP72 Heat-Shock Proteins; D018841:HSP90 Heat-Shock Proteins / Q000096:biosynthesis / Q000302:isolation & purification; D006360:Heat-Shock Proteins / Q000096:biosynthesis* / Q000302:isolation & purification; D006801:Humans; D007150:Immunohistochemistry; D018832:Molecular Chaperones; D009363:Neoplasm Proteins / Q000096:biosynthesis / Q000302:isolation & purification
D055551:HSP27 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D050884:HSP72 Heat-Shock Proteins; D018841:HSP90 Heat-Shock Proteins; C057725:HSPB1 protein, human; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D009363:Neoplasm Proteins