Role of EGR1 in regulation of stimulus-dependent CD44 transcription in B lymphocytes.
The immediate-early gene egr-1 encodes a transcription factor (EGR1) that links B-cell antigen receptor (BCR) signals to downstream activation events through the regulation of previously unidentified target genes. Here we identify the gene encoding the lymphocyte homing and migration protein CD44 as a target of EGR1 regulation in B cells. BCR-induced increases in CD44 mRNA expression and transcription levels are shown to occur in EGR1-expressing but not in nonexpressing subclones of the B-cell line WEHI-231. Kinetics of egr-1 transcription and the appearance of nuclear EGR1 protein precede CD44 induction and occur within 30 min after stimulation in the EGR1-expressing subclone. A single EGR1 binding motif is demonstrated at bp -301 of the human CD44 promoter. Cotransfection of a CD44 promoter-chloramphenicol acetyltransferase reporter construct with an egr-1 expression vector resulted in a 6.5- to 8.5-fold induction of transcriptional activity relative to an empty expression vector. The EGR1 binding motif was shown to be necessary for stimulus-induced expression of a CD44 promoter-chloramphenicol acetyltransferase reporter construct in nontransformed B lymphocytes and was required for transactivation by an EGR1 expression vector in a B-cell line. These studies identify EGR1 as an intermediary linking BCR-derived signals to the induction of CD44. The relevance of these molecular events to BCR signal transduction and antigen-stimulated B-cell-mediated immune responses is discussed.
Maltzman
J S
JS
Department of Pathology and Laboratory Medicine, University of Pennsylvania, School of Medicine, Philadelphia, 19104, USA.
Carman
J A
JA
Monroe
J G
JG
D000818:Animals; D000917:Antibody Formation; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D015500:Chloramphenicol O-Acetyltransferase / Q000096:biosynthesis; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000378:metabolism*; D051766:Early Growth Response Protein 1; D051767:Early Growth Response Protein 2; D004926:Escherichia coli; D005786:Gene Expression Regulation / Q000187:drug effects; D017781:Genes, Immediate-Early; D006801:Humans; D018960:Hyaluronan Receptors / Q000096:biosynthesis* / Q000235:genetics; D017874:Immediate-Early Proteins; D007700:Kinetics; D008070:Lipopolysaccharides / Q000494:pharmacology; D016393:Lymphoma, B-Cell; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D016755:Proto-Oncogene Proteins c-jun / Q000096:biosynthesis; D016271:Proto-Oncogene Proteins c-myc / Q000096:biosynthesis; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D015183:Restriction Mapping; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014157:Transcription Factors / Q000096:biosynthesis / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects; D014407:Tumor Cells, Cultured; D016335:Zinc Fingers
D017931:DNA Primers; D004268:DNA-Binding Proteins; C497325:EGR1 protein, human; C497326:EGR2 protein, human; D051766:Early Growth Response Protein 1; D051767:Early Growth Response Protein 2; C486109:Egr1 protein, mouse; C497327:Egr2 protein, mouse; D018960:Hyaluronan Receptors; D017874:Immediate-Early Proteins; D008070:Lipopolysaccharides; D015345:Oligonucleotide Probes; D016755:Proto-Oncogene Proteins c-jun; D016271:Proto-Oncogene Proteins c-myc; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D015500:Chloramphenicol O-Acetyltransferase; D013755:Tetradecanoylphorbol Acetate