Transcriptional activation of the chicken lysozyme gene by NF-kappa Bp65 (RelA) and c-Rel, but not by NF-kappa Bp50.

The lysozyme gene is expressed at a low level in myeloblasts and is progressively activated to constitutively high expression in mature macrophages. The binding activity of the newly defined NF-kappa B/Rel family of transcription factors increases during the terminal differentiation of macrophages. In this study, I show that NF-kappa B/Rel-like proteins bind to the nuclear factor kappa B (kappa B)-like sequence of the lysozyme promoter. These binding activities were induced by treatment of HD11 cells with lipopolysaccharide. Immunomobility shift assays show that c-Rel is possibly a factor in the complexes that bind to the kappa B-like sequence lys kappa B. Binding activity to one of the protein complexes seems to be regulated by phosphorylation. In fact, overexpression of p65 and c-Rel stimulates expression of the chloramphenicol acetyltransferase gene controlled by the lysozyme promoter. Furthermore, co-transfection experiments reveal that the kappa B-like sequence within the lysozyme promoter mediates the transactivation by p65 and c-Rel. These results indicate that the p65 and c-Rel could be components of the protein complexes that bind to the kappa B-like sequence and this binding could contribute to the progressively activated expression of the lysozyme gene during the terminal differentiation of macrophages.