An NFAT-dependent enhancer is necessary for anti-IgM-mediated induction of murine CD5 expression in primary splenic B cells
| Autor: | R, Berland, H H, Wortis |
|---|---|
| Rok vydání: | 1998 |
| Předmět: |
B-Lymphocytes
Base Composition Mice Inbred BALB C Binding Sites Base Sequence NFATC Transcription Factors Proto-Oncogene Proteins c-ets Molecular Sequence Data Nuclear Proteins CD5 Antigens Lymphocyte Activation Antibodies Anti-Idiotypic DNA-Binding Proteins Histones Mice Enhancer Elements Genetic Gene Expression Regulation Immunoglobulin M Proto-Oncogene Proteins Animals Promoter Regions Genetic Spleen Transcription Factors |
| Zdroj: | Journal of immunology (Baltimore, Md. : 1950). 161(1) |
| ISSN: | 0022-1767 |
| Popis: | CD5 is a 67-kDa membrane glycoprotein the expression of which in murine splenic B cells is induced by surface IgM cross-linking. To analyze this induction, we transiently transfected primary splenic B cells with luciferase reporter constructs driven by various wild-type and mutated CD5 5'-flanking sequences. The transfected cells were subsequently cultured in medium with or without F(ab')2 anti-IgM (anti-IgM), and luciferase expression was assayed. Using this approach, we identified a 122-bp enhancer element necessary for anti-IgM-mediated induction of the CD5 promoter. Electrophoretic mobility shift assays indicated that four inducible and four constitutive complexes form on the enhancer fragment in nuclear extracts of primary B cells. Supershift assays revealed that two of the inducible complexes contained NFATc. Point mutations that abolished NFAT binding severely impaired enhancer function. Thus, CD5 is a target of NFAT in B cells. A third inducible complex required an intact H4TF-1 site. One of several constitutive complexes required an intact Ebox site while a second required an intact putative ets binding site. Mutation of the H4TF-1, Ebox, and Ets sites, in the presence of wild-type NFAT sites, significantly reduced the activity of the enhancer. Therefore, the induction of B cell CD5 expression requires NFAT binding and binding to at least one of three additional sites in the CD5 enhancer. |
| Databáze: | OpenAIRE |
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