Human CCAAT/enhancer-binding protein beta gene expression is activated by endoplasmic reticulum stress through an unfolded protein response element downstream of the protein coding sequence.
CCAAT/enhancer-binding protein beta (C/EBPbeta) is a member of the bZIP family of transcription factors that contribute to the regulation of a wide range of important cellular processes. The data in the present study document that transcription from the human C/EBPbeta gene is induced in response to endoplasmic reticulum stress, such as glucose deprivation, or treatment of cells with tunicamycin or thapsigargin. Transient transfection of C/EBPbeta genomic fragments linked to a luciferase reporter gene demonstrated that the C/EBPbeta promoter plays no major regulatory role. Instead, by deletion analysis it was discovered that a 46-bp region, located at a genomic site that corresponds to the 3'-untranslated region of the C/EBPbeta mRNA, harbored an element that was required for the stress response. Mutagenesis demonstrated that a cis-regulatory element located at nt +1614-1621 (5'-TGACGCAA-3') is responsible for activation of the C/EBPbeta gene. Electrophoresis mobility shift analysis revealed that proteins are bound to this element and that the amount of binding is increased following glucose deprivation. This element is homologous to a previously reported mammalian unfolded protein response element that binds XBP-1. Consistent with those data, overexpression of XBP-1 caused an increase in transcription that was mediated by the C/EBPbeta mammalian unfolded protein response element.
Chen
Chin
C
Department of Biochemistry and Molecular Biology, Center for Mammalian Genetics, and Center for Nutritional Sciences, University of Florida College of Medicine, Gainesville, FL 32610-0245, USA.
Dudenhausen
Elizabeth E
EE
Pan
Yuan-Xiang
YX
Zhong
Can
C
Kilberg
Michael S
MS
D001483:Base Sequence; D001665:Binding Sites; D015152:Blotting, Northern; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000096:biosynthesis*; D002460:Cell Line; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D017353:Gene Deletion; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D005947:Glucose / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D008156:Luciferases / Q000378:metabolism; D008957:Models, Genetic; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D017510:Protein Folding; D012333:RNA, Messenger / Q000378:metabolism; D020218:Response Elements; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019284:Thapsigargin / Q000494:pharmacology; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection; D014415:Tunicamycin / Q000494:pharmacology
D022782:CCAAT-Enhancer-Binding Protein-beta; D012333:RNA, Messenger; D014157:Transcription Factors; D014415:Tunicamycin; D019284:Thapsigargin; D008156:Luciferases; D005947:Glucose