Related Experiment Videos
A c-Rel subdomain responsible for enhanced DNA-binding affinity and selective gene activation
Shomyseh Sanjabi1, Kevin J Williams, Simona Saccani
1Howard Hughes Medical Institute, Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, CA 90095-1662, USA.
Genes & Development
|September 17, 2005
Summary
Unique residues in c-Rel dictate gene regulation distinct from p65 by altering DNA binding affinity. This explains how related transcription factors control different genes despite similar DNA recognition sequences.
Area of Science:
- Molecular Biology
- Immunology
- Genetics
Background:
- Nuclear factor-kappaB (NF-kappaB) family members, p65 (RelA) and c-Rel, bind similar DNA sequences.
- Despite sequence similarity, mutant mouse phenotypes indicate distinct gene regulation by p65 and c-Rel.
Purpose of the Study:
- To identify the specific regions within c-Rel responsible for its unique gene induction functions.
- To elucidate the mechanism by which c-Rel regulates distinct gene sets compared to p65.
Main Methods:
- Analysis of mutant mouse phenotypes.
- Site-directed mutagenesis within the Rel homology region (RHR) of c-Rel.
- Gene induction assays (Il12b and Il12a) in macrophages and dendritic cells stimulated with lipopolysaccharide.
- DNA binding affinity studies of c-Rel and p65 homodimers to NF-kappaB recognition sequences.
Main Results:
- A 46-residue segment in the c-Rel RHR is critical for Il12b gene induction in macrophages and Il12a induction in dendritic cells.
- No evidence of c-Rel-specific coactivator interactions was found.
- c-Rel homodimers and a chimeric p65 protein with c-Rel residues exhibit higher binding affinity to a broader range of NF-kappaB sequences than wild-type p65.
Conclusions:
- Differences in DNA sequence recognition range, driven by specific residues, dictate the unique functions of related transcription factors like c-Rel and p65.
- High-affinity binding to a broader set of DNA sequences contributes to the distinct gene regulatory roles of NF-kappaB family members.