The c-rel protooncogene product c-Rel but not NF-kappa B binds to the intronic region of the human interferon-gamma gene at a site related to an interferon-stimulable response element.
Interferon-gamma (IFN-gamma) is an important immunoregulatory protein that is expressed usually only in large granular lymphocytes and T cells. The gene encoding IFN-gamma was previously found to contain an intronic enhancer element that was not tissue-specific in its activity, despite the restricted expression of the intact IFN-gamma-encoding gene. Using nuclear extracts from the human T-cell line Jurkat, we have now identified two protein-binding regions in this intronic enhancer element. One of the protected regions has strong partial identify to the NF-kappa B site present in the promoter region of the human interleukin 2-encoding gene. Based on this observation and recent reports of the interaction of the c-rel protooncogene product (c-Rel) with NF-kappa B sites, we determined whether c-Rel could interact with the intronic enhancer element in the human IFN-gamma genomic DNA. Most surprisingly, gel-shift analysis, using c-Rel expressed in Escherichia coli established that c-Rel binds specifically to the IFN-gamma intronic DNA but not to the interleukin 2-like NF-kappa B site. Additional studies with antibodies prepared against c-Rel peptides verified specificity of the interaction of c-Rel with this binding site. In addition, using an affinity-purified p50 subunit of the NF-kappa B complex, we observed that the p50 protein did not bind to this additional c-Rel-binding site. Furthermore, nucleotide sequence analysis of this DNA region revealed a strong similarity of the additional c-Rel-binding site to a previously identified IFN-stimulable response element. These data show that c-Rel can interact with DNA regions distinct from that recognized by NF-kappa B and may, in fact, be involved in transcriptional regulation of the IFN-stimulable genes via the IFN-stimulable response element.
Sica
A
A
Laboratory of Experimental Immunology, Program Resources, Inc./DynCorp, Frederick, MD.
Tan
T H
TH
Rice
N
N
Kretzschmar
M
M
Ghosh
P
P
Young
H A
HA
D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D066298:In Vitro Techniques; D007371:Interferon-gamma / Q000235:genetics*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D016328:NF-kappa B / Q000378:metabolism*; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D011485:Protein Binding; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D020569:Proto-Oncogene Proteins c-rel; D012333:RNA, Messenger / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid; D012689:Sequence Homology, Nucleic Acid
D004268:DNA-Binding Proteins; D016328:NF-kappa B; D009838:Oligodeoxyribonucleotides; D011518:Proto-Oncogene Proteins; D020569:Proto-Oncogene Proteins c-rel; D012333:RNA, Messenger; D007371:Interferon-gamma