Study type: Medical/biological study (experimental study)

CREB DNA binding activation by a 50-Hz magnetic field in HL60 cells is dependent on extra- and intracellular Ca2+ but not PKA, PKC, ERK, or p38 MAPK. med./bio.

Published in: Biochem Biophys Res Commun 2002; 296 (4): 1013-1018

Aim of study (acc. to author)

To investigate the effects of exposure to a 0.1 mT 50 Hz extremely low frequency sinusoidal magnetic field on DNA binding activity of CREB transcription factors in human cells.

Background/further details

CREB (cyclic-AMP responsive element binding protein) is a transcription factor that is target of a variety of signal transduction pathways mediating cell responses to extracellular stimuli, involving proliferation, or differentiation. Since several signal transduction pathways are involved in activation of CREB, the effects of various inhibitors on magnetic field-induced CREB binding activity were also investigated (inhibitors of different signal transduction pathways, e.g. PKA, PKC, ERK (extracellular signal-regulated kinase), p38 MAPK (p38 mitogen-activated protein kinase)). Furthermore, the relevance of intracellular and extracellular Ca2+ concentrations were examined by using Ca2+ chelators.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: 10 min, 0.5, 1, 2, 4, and 12 hrs (sham exposure for 12 hrs)

Exposure 1

Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration 10 min, 0.5, 1, 2, 4, and 12 hrs (sham exposure for 12 hrs)
Exposure setup
Exposure source
Chamber The coils were placed in a mu-metal container.
Setup The magnetic field was very uniform (0.1%) at the center (10 x 10 x 10 cm³) of the coils where the cell cultures dishes were placed. Sham-exposed cells were handled in the same manner but without the magnetic field.
Additional info Three groups of square copper coils 36 cm x 36 cm with the upper, middle and lower coils having 104, 52 and 104 turns, respectively. They were spaced 18 cm from each other.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 0.1 mT unspecified measured - -

Reference articles

  • Zhou J et al. (2002): Gene expression of cytokine receptors in HL60 cells exposed to a 50 Hz magnetic field.

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • during exposure
  • after exposure

Main outcome of study (acc. to author)

Exposure to magnetic field induced a time-dependent activation of CREB-DNA-binding. The CREB complex formation increased shortly after magnetic field exposure for 10 minutes, reaching a peak level after 1 hour, and then recovered to basal level at 4 hours after exposure.
Furthermore, the exposure to magnetic field-induced increase of CREB-DNA-binding was dependent on both extracellular and intracellular Ca2+ concentration but not on PKA, PKC, ERK, or p38 MAPK by using various signal transduction pathway inhibitors.
These results indicate that magnetic field exposure activates CREB-DNA-binding through Ca2+-related signal transduction pathways.

Study character:

Study funded by

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