earticle

영어

To cope with multiple stresses caused by various biotic and abiotic stimuli and consequently increased accumulation of misfolded proteins, eukaryotic cells activate a series of adaptive mechanisms that are known as the unfolded protein response (UPR). In response to cellular stresses, phosphorylation of the α subunit of eukaryotic initiation factor 2 (eIF2α) attenuates general protein synthesis. However, it also favors the selective translation of mRNAs with upstream open reading frames (uORFs) such as ATF4, a key regulator of the integrated stress response (ISR), in mammalian cells. The ISR is an evolutionarily conserved translational and transcriptional program initiated upon phosphorylation of eIF2α. However, no studies to date have been conducted on the ISR mediated by phosphorylation of eIF2α, and key regulators responsible for the ISR have not been identified in plants. In this study, we performed in silico analysis to investigate functional orthologs of the ATF4, and confirmed that some genes belong to bZIP family containing uORFs in the 5′UTR are potential candidates. However, it is not well understood whether they are involved in plant ISR mediated by phosphorylation of eIF2α. During prolonged ER stress, transcription of these genes increased by 2-3 fold. Arabidopsis plants overexpressing showed a more sensitive phenotype than Col-0 and knockout mutant plants under tunicamycin-induced ER stress condition, while plants overexpressing with uORF did not show any difference. In addition, the expression level of bZIP GFP fusion protein without uORF is increased under ER stress conditions compare to normal conditions. These results suggest that uORF-containing bZIP genes may have a role in plant ISR. * Corresponding