Nanosecond pulsed electric fields induce the integrated stress response via reactive oxygen species-mediated heme-regulated inhibitor (HRI) activation.

ABSTRACT: The integrated stress response (ISR) is one of the most important cytoprotective mechanisms and is integrated by phosphorylation of the ? subunit of eukaryotic translation initiation factor 2 (eIF2?). Four eIF2? kinases, heme-regulated inhibitor (HRI), double-stranded RNA-dependent protein kinase (PKR), PKR-like endoplasmic reticulum kinase (PERK), and general control nonderepressible 2 (GCN2), are activated in response to several stress conditions. We previously reported that nanosecond pulsed electric fields (nsPEFs) are a potential therapeutic tool for ISR activation. In this study, we examined which eIF2? kinase is activated by nsPEF treatment. To assess the responsible eIF2? kinase, we used previously established eIF2? kinase quadruple knockout (4KO) and single eIF2? kinase-rescued 4KO mouse embryonic fibroblast (MEF) cells. nsPEFs 70 ns in duration with 30 kV/cm electric fields caused eIF2? phosphorylation in wild-type (WT) MEF cells. On the other hand, nsPEF-induced eIF2? phosphorylation was completely abolished in 4KO MEF cells and was recovered by HRI overexpression. CM-H2DCFDA staining showed that nsPEFs generated reactive oxygen species (ROS), which activated HRI. nsPEF-induced eIF2? phosphorylation was blocked by treatment with the ROS scavenger N-acetyl-L-cysteine (NAC). Our results indicate that the eIF2? kinase HRI is responsible for nsPEF-induced ISR activation and is activated by nsPEF-generated ROS.

SUBMITTER: Hamada Y 

PROVIDER: S-EPMC7064201 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature