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

To investigate the possible mechanism of gene transcription changes induced by magnetic field (MF), we examined the DNA binding behavior of the transcription factor cyclic-AMP responsive element binding protein (CREB) in HL60 cells after exposure to a 0.1 mT 50-Hz extremely low frequency (ELF) sinusoidal MF by a gel shift assay. Magnetic field induced a time-dependent activation of CREB binding. The complex formation increased shortly after MF exposure for 10 min, reaching a peak level after 1 h, and then recovered to basal level at 4 h after exposure. A novel MF-induced ATF2/ATF2 homodimer formation was observed after MF exposure for 30 min, 1, and 2 h. Furthermore, We found that the MF-induced increase of CREB DNA binding in HL60 cells was dependent on both extracellular and intracellular Ca²⁺ but not PKA, PKC, ERK, or p38 MAPK by using various pathway inhibitors. These data indicate that MF exposure activates CREB DNA binding through calcium-related signal transduction pathways under our experimental conditions.