CHARACTERIZATION OF THE MOUSE GRANULOCYTE-MACROPHAGE COLONY-STIMULATING FACTOR (GM-CSF) GENE PROMOTER - NUCLEAR FACTORS THAT INTERACT WITH AN ELEMENT SHARED BY 3 LYMPHOKINE GENES - THOSE FOR GM-CSF, INTERLEUKIN-4 (IL-4), AND IL-5

The region extending from -40 to -54 of the 5'-flanking region of the mouse granulocyte-macrophage colony-stimulating factor (GM-CSF) gene shows homology to sequences found in the 5'-flanking regions of other cytokine genes, those encoding interleukin-4 (IL-4), IL-5, and granulocyte colony-stimulating factor (G-CSF). This sequence element is referred to as conserved lymphokine element 0 (CLE0). Saturation mutagenesis of the CLE0 element indicates that in addition to the previously mapped region between -73 and -91 (CLE2+GC box), the CLE0 element is necessary for induction of the mouse GM-CSF gene by phorbol myristate acetate/Ca ionophore (A23187) stimulation in T cells. The presence of the CLE0 element is necessary to observe stimulation of the transcription activity of the mouse GM-CSF promoter in vitro. Mobility shift assays revealed that this region forms an inducible DNA-protein complex, NF-CLE0, which consists of two complexes of similar mobility, NF-CLE0a and NF-CLE0b. NF-CLE0a and NF-CLE0b recognize the 3' half and 5' half of the CLE0 element, respectively, with an overlapping region recognized by both proteins. The recognition sequence of NF-CLE0a corresponds to the region required for induction by phorbol myristate acetate/A23187, while the recognition sequence of NF-CLE0b contains bases that have inhibitory activity. The CLE0 elements of the IL-4 and IL-5 genes but not the G-CSF gene are also recognized by NF-CLE0a and -b, suggesting that the NF-CLE0a and -b proteins play an important role in the coordinate induction of these genes in activated T cells. The nuclear factor that recognizes the G-CSF CLE0 element seems to be different from NF-CLE0a and NF-CLE0b; however, it weakly recognizes the DNA sequence for the NF-CLE0a.