The Influence of Applying High Electrical Field Pulses on Unfolded Protein Responce of Cells Preparation of*

The application of pulsed power technology is spreading to biotechnology and medical fields. Pulse electric fields yield various influences on cells. Endoplasmic reticulum (ER) stress which is due to accumulation of unfolded proteins has been considered as one of disorder such as diabetes and Alzheimer. Unfolded protein response (UPR) is a built-in avoiding function of ER stress and conduct reactions as promotion and pausing of folding. The activation of UPR by application of nsPEFs on cells was studied. Here, proper conditions to activate UPR were explored in experiments. Eukaryotic translation initiation factor 2 subunit a (eIF2a) is phosphorylated and translation of protein is inhibited when cells are stressed. Transportations of protein before folding to ER are accordingly inhibited and the process is UPR. In this experiment, phosphorylated eIF2a (P-eIF2a) was observed to estimate the induction of UPR. Electric fields pulses of 14 ns and 70 ns in pulse width were applied on MEF and HeLa cells and expression of P-eIF2a was evaluated by Western blotting. First, relatively high electric fields pulses: over 120 kV/cm were applied. Second, under 70 kV/cm pulses were applied. Thapsigargin was used for positive control. The P-eIF2a expression of high electric field pulse applied samples was smaller than that of low electric field samples. The cell death and the P-eIF2a dephosphorylation was considered as the reason.