The mammalian endoplasmic reticulum stress response element consists of an evolutionarily conserved tripartite structure and interacts with a novel stress-inducible complex.
When mammalian cells are subjected to calcium depletion stress or protein glycosylation block, the transcription of a family of glucose-regulated protein (GRP) genes encoding endoplasmic reticulum (ER) chaperones is induced to high levels. The consensus mammalian ER stress response element (ERSE) conserved among grp promoters consists of a tripartite structure CCAAT(N9)CCACG, with N being a strikingly GC-rich region of 9 bp. The ERSE, in duplicate copies, can confer full stress inducibility to a heterologous promoter in a sequence-specific but orientation-independent manner. In addition to CBF/NF-Y and YY1 binding to the CCAAT and CCACG motifs, respectively, we further discovered that an ER stress-inducible complex (ERSF) from HeLa nuclear extract binds specifically to the ERSE. Strikingly, the interaction of the ERSF with the ERSE requires a conserved GGC motif within the 9 bp region. Since mutation of the GGC triplet sequence also results in loss of stress inducibility, specific sequence within the 9 bp region is an integral part of the tripartite structure. Finally, correlation of factor binding with stress inducibility reveals that ERSF binding to the ERSE alone is not sufficient; full stress inducibility requires integrity of the CCAAT, GGC and CCACG sequence motifs, as well as precise spacing among these sites.
Roy
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Department of Biochemistry and Molecular Biology and the USC/Norris Comprehensive Cancer Center,University of Southern California School of Medicine, Los Angeles, CA 90033, USA.
Lee
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D000220:Adaptation, Biological / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D022762:CCAAT-Enhancer-Binding Proteins; D002118:Calcium / Q000378:metabolism; D017124:Conserved Sequence; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D050981:Erythroid-Specific DNA-Binding Factors; D019143:Evolution, Molecular; D006367:HeLa Cells; D006801:Humans; D008565:Membrane Proteins / Q000096:biosynthesis*; D018832:Molecular Chaperones / Q000096:biosynthesis*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D051381:Rats; D020218:Response Elements; D019284:Thapsigargin / Q000494:pharmacology; D014157:Transcription Factors / Q000378:metabolism; D050986:YY1 Transcription Factor
D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; D050981:Erythroid-Specific DNA-Binding Factors; D008565:Membrane Proteins; D018832:Molecular Chaperones; D014157:Transcription Factors; D050986:YY1 Transcription Factor; C494698:YY1 protein, human; C494700:Yy1 protein, rat; D019284:Thapsigargin; D002118:Calcium