Electromagnetic field effects: changes in protein phosphorylation in the Jurkat E6.1 cell line

This study is aimed at expanding the role of electromagnetic field (EMF) therapy for treatment of inflammatory diseases and obtaining new information on the biophysical mechanism of action of weak EMFs. The mechanism of action of EMFs on biological systems is a question that has yet to be answered. Several models have been proposed to explain the coupling of low frequency fields to biological systems, although no consensus has been reached as to which most adequately portrays the true mechanism. Protein phosphorylation is a major cellular metabolic regulator. As such, it has the potential to be a valuable indicator of the impact of EMFs on cellular metabolism. Using a well-controlled EMF exposure system, we examined the regulatory role of EMFs on low molecular weight protein phosphorylation in Jurkat E6.1 cells, a transformed human leukemic T cell line. Jurkat cells were grown to mid-log phase, preloaded with 32P and exposed to EMF (0.1 mT, 60 Hz) or sham for 30 minutes. Cell proteins were separated by SDS-polyacrylamide gel electrophoresis and incorporated radioactivity of low molecular weight proteins (18-23 kDa) was quantified by AMBIS data analysis. Three of five experiments showed no difference in protein phosphorylation in EMF exposed samples compared to controls, while two experiments revealed an EMF effect. We identified stathmin, an important T cell signaling phosphoprotein, as one of the low molecular weight proteins present in our Jurkat cell system. Stathmin expression as well as its phosphorylation was decreased in samples that were exposed to EMFs compared to controls. These data indicate that phosphorylation of individual proteins might be masked by the presence of numerous other proteins in whole cell lysate experiments. Further studies testing other low molecular weight T cell signaling molecules may validate this hypothesis.