LOCALIZATION OF THE INDUCIBLE ENHANCER IN THE MOUSE INTERLEUKIN-5 GENE THAT IS RESPONSIVE TO T-CELL RECEPTOR STIMULATION

Transcriptional regulation of the interleukin-5 (IL-5) gene in T lymph ocytes appears to be of central importance in the control of the eosin ophilia characteristic of allergic responses and certain parasite infe ctions. Previous studies of IL-5 gene regulation have been hampered by the lack of a transfection assay, which detects the antigen-responsiv e enhancer in the IL-5 promoter. Here we show that stable transfection of the Th2 clone D10.G4.1 and the T lymphoma EL4.23 with chlorampheni col acetyltransferase reporter gene constructs carrying the region to -3859 gives inducible expression with the known regulatory characteris tics of the endogenous IL-5 gene, To facilitate detailed analysis of t he promoter region, 3.9 kb of DNA sequence immediately up stream of th e start of transcription was determined and the minimum upstream regio n required for inducible expression was further localized, by stable t ransfection studies in EL4.23 cells, to the region up to -1016, A CTF/ NF1 site in the upstream enhancer at -940 to -928 was shown to be requ ired for regulated inducible expression. Mutation of this sequence mot if abolished inducibility and also prevented binding of the sequence t o a nuclear protein(s). A TCATTT-containing element in the proximal pr omoter region was also demonstrated to be essential for inducible expr ession of the IL-5 gene, similar to the role of this conserved element in the transcriptional regulation of the granulocyte-macrophage colon y-stimulating factor (GM-CSF) and IL-4 genes. (C) 1995 by The American Society of Hematology.