Suppression of grp78 core promoter element-mediated stress induction by the dbpA and dbpB (YB-1) cold shock domain proteins.
The highly conserved grp78 core promoter element plays an important role in the induction of grp78 under diverse stress signals. Previous studies have established a functional region in the 3' half of the core (stress-inducible change region [SICR]) which exhibits stress-inducible changes in stressed nuclei. The human transcription factor YY1 is shown to bind the SICR and transactivate the core element under stress conditions. Here we report that expression library screening with the core element has identified two new core binding proteins, YB-1 and dbpA. Both proteins belong to the Y-box family of proteins characterized by an evolutionarily conserved DNA binding motif, the cold shock domain (CSD). In contrast to YY1, which binds only double-stranded SICR, the Y-box/CSD proteins much prefer the lower strand of the SICR. The Y-box proteins can repress the inducibility of the grp78 core element mediated by treatment of cells with A23187, thapsigargin, and tunicamycin. In gel shift assays, YY1 binding to the core element is inhibited by either YB-1 or dbpA. A yeast interaction trap screen using LexA-YY1 as a bait and a HeLa cell cDNA-acid patch fusion library identified YB-1 as a YY1-interacting protein. In cotransfection experiments, the Y-box proteins antagonize the YY1-mediated enhancement of transcription directed by the grp78 core in stressed cells. Thus, the CSD proteins may be part of the stress signal transduction mechanism in the mammalian system.
Li
W W
WW
Department of Biochemistry and Molecular Biology, Norris Cancer Center, University of Southern California School of Medicine, Los Angeles 90033, USA.
Hsiung
Y
Y
Wong
V
V
Galvin
K
K
Zhou
Y
Y
Shi
Y
Y
Lee
A S
AS
D001426:Bacterial Proteins / Q000235:genetics; D022762:CCAAT-Enhancer-Binding Proteins; D002352:Carrier Proteins / Q000235:genetics*; D003001:Cloning, Molecular; D003080:Cold Temperature; D004277:DNA, Single-Stranded / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D000091342:Endoplasmic Reticulum Chaperone BiP; D050981:Erythroid-Specific DNA-Binding Factors; D006367:HeLa Cells; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D018832:Molecular Chaperones / Q000235:genetics*; D008969:Molecular Sequence Data; D051839:NFI Transcription Factors; D009687:Nuclear Proteins; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017422:Sequence Analysis, DNA; D012697:Serine Endopeptidases / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation; D014162:Transfection; D051840:Y-Box-Binding Protein 1; D050986:YY1 Transcription Factor; D000099160:LexA Repressor Protein
D001426:Bacterial Proteins; D022762:CCAAT-Enhancer-Binding Proteins; D002352:Carrier Proteins; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D000091342:Endoplasmic Reticulum Chaperone BiP; D050981:Erythroid-Specific DNA-Binding Factors; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D051839:NFI Transcription Factors; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D012697:Serine Endopeptidases; D014157:Transcription Factors; D051840:Y-Box-Binding Protein 1; D050986:YY1 Transcription Factor; D000099160:LexA Repressor Protein; C000717247:HSPA5 protein, human; C070856:YBX1 protein, human; C094867:YBX3 protein, human; C494698:YY1 protein, human