High level activity of the mouse CCAAT/enhancer binding protein (C/EBP alpha) gene promoter involves autoregulation and several ubiquitous transcription factors.
AUTOR(ES)
Legraverend, C
RESUMO
The promoter region of the mouse CCAAT-Enhancer Binding Protein (C/EBP alpha) gene is capable of directing high levels of expression of reporter constructs in various cell lines, albeit even in cells that do not express their endogenous C/EBP alpha gene. To understand the molecular mechanisms underlying this ubiquitous expression, we have characterized the promoter region of the mouse C/EBP alpha gene by a variety of in vitro and in vivo methods. We show that three sites related in sequence to USF, BTE and C/EBP binding sites and present in promoter region -350/+3, are recognized by proteins from rat liver nuclear extracts. The sequence of the C/EBP alpha promoter that includes the USF binding site is also capable of forming stable complexes with purified Myc+Max heterodimers and mutation of this site drastically reduces transcription of C/EBP alpha promoter luciferase constructs both in liver and non liver cell lines. In addition, we identify three novel protein-binding sites two of which display similarity to NF-1 and a NF kappa B binding sites. The region located between nucleotides -197 and -178 forms several heat-stable complexes with liver nuclear proteins in vitro which are recognized mainly by antibodies specific for C/EBP alpha. Furthermore, transient expression of C/EBP alpha and to a lesser extent C/EBP beta expression vectors, results in transactivation of a cotransfected C/EBP alpha promoter-luciferase reporter construct. These experiments support the notion that the C/EBP alpha gene is regulated by C/EBP alpha but other C/EBP-related proteins may also be involved.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=309408Documentos Relacionados
- CCAAT/enhancer binding protein alpha (C/EBP alpha) undifferentiated protein: a developmentally regulated nuclear protein that binds to the C/EBP alpha gene promoter.
- The liver-specific promoter of the human insulin-like growth factor II gene is activated by CCAAT/enhancer binding protein (C/EBP).
- Growth-dependent inhibition of CCAAT enhancer-binding protein (C/EBP alpha) gene expression during hepatocyte proliferation in the regenerating liver and in culture.
- Transcriptional activation of the mouse obese (ob) gene by CCAAT/enhancer binding protein alpha.
- CCAAT/enhancer binding protein (C/EBP) sites are required for HIV-1 replication in primary macrophages but not CD4+ T cells