Induction of stress proteins by electromagnetic fields in cultured HL-60 cells

Bioelectromagnetics. 1999 Sep;20(6):347-57. doi: 10.1002/(sici)1521-186x(199909)20:6<347::aid-bem3>3.0.co;2-i.

Abstract

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.

MeSH terms

  • Electromagnetic Fields / adverse effects*
  • Electrophoresis, Gel, Two-Dimensional
  • HL-60 Cells
  • HSP27 Heat-Shock Proteins
  • HSP70 Heat-Shock Proteins / biosynthesis
  • HSP70 Heat-Shock Proteins / isolation & purification
  • HSP72 Heat-Shock Proteins
  • HSP90 Heat-Shock Proteins / biosynthesis
  • HSP90 Heat-Shock Proteins / isolation & purification
  • Heat-Shock Proteins / biosynthesis*
  • Heat-Shock Proteins / isolation & purification
  • Humans
  • Immunohistochemistry
  • Molecular Chaperones
  • Neoplasm Proteins / biosynthesis
  • Neoplasm Proteins / isolation & purification

Substances

  • HSP27 Heat-Shock Proteins
  • HSP70 Heat-Shock Proteins
  • HSP72 Heat-Shock Proteins
  • HSP90 Heat-Shock Proteins
  • HSPB1 protein, human
  • Heat-Shock Proteins
  • Molecular Chaperones
  • Neoplasm Proteins