CHARACTERIZATION OF NUCLEAR FACTORS THAT BIND TO A CRITICAL POSITIVE REGULATORY ELEMENT OF THE HUMAN GRANULOCYTE-MACROPHAGE COLONY-STIMULATING FACTOR PROMOTER

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a hematop oietic growth factor that stimulates the proliferation, maturation, an d functional activity of myeloid cells in peripheral blood and bone ma rrow. Expression of GM-CSF is tightly regulated and is limited to cell s stimulated directly (T cells, macrophages) or indirectly (fibroblast s, endothelial cells) by immune challenge. Several studies of the tran scriptional control of GM-CSF expression have elucidated a region of t he GM-CSF promoter that mediates positive regulatory activity in a num ber of cell types. This region contains a direct repeat of the sequenc e CATT(A)/T that extends from nucleotides -37 to -48 upstream of the s tart of mRNA synthesis. Although specific DNA:protein interactions hav e been shown within this region, neither the nature nor the number of nuclear factors responsible for these interactions have been character ized. In this study, we use DNase I footprinting analysis to demonstra te that point mutations. which inactivate the GM-CSF promoter, disrupt DNA:protein interactions within this region. By combined electrophore tic mobility shift and ultraviolet cross-linking analysis, we have det ected several protein species that bind specifically to the positive r egulatory sequence. (C) 1994 by The American Society of Hematology.