c-Myb Binds to a Sequence in the Proximal Region of the RAG-2 Promoter and Is Essential for Promoter Activity in T-Lineage Cells
AUTOR(ES)
Wang, Qian-Fei
FONTE
American Society for Microbiology
RESUMO
The RAG-2 gene encodes a component of the V(D)J recombinase which is essential for the assembly of antigen receptor genes in B and T lymphocytes. Previously, we reported that the transcription factor BSAP (PAX-5) regulates the murine RAG-2 promoter in B-cell lines. A partially overlapping but distinct region of the proximal RAG-2 promoter was also identified as an important element for promoter activity in T cells; however, the responsible factor was unknown. In this report, we present data demonstrating that c-Myb binds to a Myb consensus site within the proximal promoter and is critical for its activity in T-lineage cells. We show that c-Myb can transactivate a RAG-2 promoter-reporter construct in cotransfection assays and that this transactivation depends on the proximal promoter Myb consensus site. By using a chromatin immunoprecipitation (ChIP) strategy, fractionation of chromatin with anti-c-Myb antibody specifically enriched endogenous RAG-2 promoter DNA sequences. DNase I genomic footprinting revealed that the c-Myb site is occupied in a tissue-specific fashion in vivo. Furthermore, an integrated RAG-2 promoter construct with mutations at the c-Myb site was not enriched in the ChIP assay, while a wild-type integrated promoter construct was enriched. Finally, this lack of binding of c-Myb to a chromosomally integrated mutant RAG-2 promoter construct in vivo was associated with a striking decrease in promoter activity. We conclude that c-Myb regulates the RAG-2 promoter in T cells by binding to this consensus c-Myb binding site.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=102178Documentos Relacionados
- c-Myb is essential for early T cell development
- The T11 glycoprotein is functionally linked to a calcium channel in precursor and mature T-lineage cells.
- Resistance to apoptosis in CTLL-2 cells constitutively expressing c-Myb is associated with induction of BCL-2 expression and Myb-dependent regulation of bcl-2 promoter activity
- Protein truncation is not required for c-myb proto-oncogene activity in neuroretina cells.
- Positive autoregulation of c-myb expression via Myb binding sites in the 5' flanking region of the human c-myb gene.