Displacement of an E-box-binding repressor by basic helix-loop-helix proteins: implications for B-cell specificity of the immunoglobulin heavy-chain enhancer.
AUTOR(ES)
Genetta, T
RESUMO
The activity of the immunoglobulin heavy-chain (IgH) enhancer is restricted to B cells, although it binds both B-cell-restricted and ubiquitous transcription factors. Activation of the enhancer in non-B cells upon overexpression of the basic helix-loop-helix (bHLH) protein E2A appears to be mediated not only by the binding of E2A to its cognate E box but also by the resulting displacement of a repressor from that same site. We have identified a "two-handed" zinc finger protein, denoted ZEB, the DNA-binding specificity of which mimics that of the cellular repressor. By employing a derivative E box that binds ZEB but not E2A, we have shown that the repressor is active in B cells and the IgH enhancer is silenced in the absence of binding competition by bHLH proteins. Hence, we propose that a necessary prerequisite of enhancer activity is the B-cell-specific displacement of a ZEB-like repressor by bHLH proteins.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=359142Documentos Relacionados
- ETS-Mediated Cooperation between Basic Helix-Loop-Helix Motifs of the Immunoglobulin μ Heavy-Chain Gene Enhancer
- Selective utilization of basic helix-loop-helix-leucine zipper proteins at the immunoglobulin heavy-chain enhancer.
- Localization of a repressive sequence contributing to B-cell specificity in the immunoglobulin heavy-chain enhancer.
- Complex protein binding within the mouse immunoglobulin heavy-chain enhancer.
- Negative regulation contributes to tissue specificity of the immunoglobulin heavy-chain enhancer.
