Sequence elements required for function of the MHC class II A beta gene promoter in murine macrophages.

We have studied the DNA sequence elements of the murine MHC class II A beta gene involved in transcriptional regulation in macrophages. For this study, the A beta promoter was fused to the human growth hormone gene and transfected into bone marrow-derived macrophages. These macrophages were stimulated by interferon-gamma (IFN-gamma), after which cellular RNA was assayed for the amount of human growth hormone transcripts. A -146 to +14 fragment of the A beta promoter was found to be sufficient to confer positive regulation by IFN-gamma. Induction was suppressed by bacterial lipopolysaccharide, tumor necrosis factor (TNF-alpha), or maley-lated bovine serum albumin. Substitution mutations were made within each of the conserved sequence elements of the promoter as well as within the spacer regions between these elements. All four conserved sequences found in class II promoters, the H, X1, X2, and Y elements, were found to be essential for promoter activation in macrophages.