The Upstream 1350~1250 Nucleotide Sequences of the Human Gene Contain Critical -Elements Responsible for Upregulating Its Transcription during ER Stress.

encodes an endoribonuclease that overcomes the inhibitory upstream open reading frame (uORF)-trap at 5'-untranslated region (UTR) of the transcript, allowing the downstream coding sequence of be translated during endoplasmic reticulum (ER) stress. However, transcriptional control of remains enigmatic. To address this, we cloned an upstream 2.1 kb (-2055~+77 bp) of human (pE2.1p) fused with reporter luciferase (luc) cDNA. The promoter strength driven by pE2.1p was significantly upregulated in both pE2.1p-transfected cells and pE2.1p-injected zebrafish embryos treated with stress inducers. Comparing the luc activities driven by pE2.1p and -1125~+77 (pE1.2p) segments, we revealed that -elements located at the -2055~-1125 segment might play a critical role in upregulation during ER stress. Since bioinformatics analysis predicted many -elements clustered at the -1850~-1250, we further deconstructed this segment to generate pE2.1p-based derivatives lacking -1850~-1750, -1749~-1650, -1649~-1486, -1485~-1350 or -1350~-1250 segments. Quantification of promoter activities driven by these five internal deletion plasmids suggested a repressor binding element within the -1649~-1486 and an activator binding element within the -1350~-1250. Since luc activities driven by the -1649~-1486 were not significantly different between normal and stress conditions, we herein propose that the stress-inducible activator bound at the -1350~-1250 segment makes a major contribution to the increased expression of human upon ER stresses.