title: Role of Egr-1 gene expression in B cell receptor-induced apoptosis in an immature B cell lymphoma.
abstract: Ligation of B cell receptor (BCR) on BKS-2, an immature B cell lymphoma by anti-IgM antibodies (Ab) caused apoptosis. Here we report that signaling through B cell receptor in wild type BKS-2 cells down-regulated the expression of Egr-1, a zinc finger-containing transcription factor. A reduction in the level of Egr-1 mRNA could be demonstrated as early as 30 min after the ligation of BCR on BKS-2 cells. Immunocytochemical and Western blot analysis revealed that the expression of EGR-1 protein was also inhibited by anti-IgM treatment. Antisense oligonucleotides to Egr-1 caused growth inhibition and apoptosis in BKS-2 cells, suggesting that expression of Egr-1 is important for the survival of these B lymphoma cells. In contrast to wild type BKS-2 cells, the mutant 1. B5 cell line, which is refractory to B cell receptor-mediated growth-inhibitory signals, showed an increased expression of Egr-1 upon treatment with anti-IgM. These results implicate a role for Egr-1 in blocking B cell receptor-mediated apoptosis in immature B cells.
authors.affiliation: Department of Microbiology and Immunology, Division of Urology, University of Kentucky, Lexington, Kentucky 40536, USA.
authors.forename: S
authors.initials: S
authors.lastname: Muthukkumar
authors.forename: S S
authors.initials: SS
authors.lastname: Han
authors.forename: V M
authors.initials: VM
authors.lastname: Rangnekar
authors.forename: S
authors.initials: S
authors.lastname: Bondada
mesh_terms: D000818:Animals; D000906:Antibodies / Q000276:immunology; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics* / Q000502:physiology; D004268:DNA-Binding Proteins / Q000235:genetics*; D051766:Early Growth Response Protein 1; D005786:Gene Expression Regulation / Q000276:immunology; D017874:Immediate-Early Proteins; D007075:Immunoglobulin M / Q000276:immunology; D007150:Immunohistochemistry; D016393:Lymphoma, B-Cell / Q000473:pathology*; D051379:Mice; D008808:Mice, Inbred CBA; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics; D011947:Receptors, Antigen, B-Cell / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics*; D014407:Tumor Cells, Cultured
chemical_list: D000906:Antibodies; D004268:DNA-Binding Proteins; D051766:Early Growth Response Protein 1; C486109:Egr1 protein, mouse; D017874:Immediate-Early Proteins; D007075:Immunoglobulin M; D016376:Oligonucleotides, Antisense; D012333:RNA, Messenger; D011947:Receptors, Antigen, B-Cell; D014157:Transcription Factors