Ubiquitous and lymphocyte-specific factors are involved in the induction of the mouse interleukin 2 gene in T lymphocytes

Abstract

The immediate upstream region of the mouse interleukin 2 (IL-2) gene harbors a strong transcriptional enhancer. This enhancer contains most, if not all of the sequence elements necessary for the T cell specific induction of the IL-2 gene by the phorbol ester TPA and the plant lectin Concanavalin A. DNase I footprinting studies with fractionated extracts obtained from induced and uninduced E14 T cells revealed numerous recognition sites for potential trans-acting factors. Five of these sites are also recognized by the TPA-activated HeLa cell factors AP-1 and AP-3. Other sites including two TATA-boxes, two purine-rich sequence motifs and two copies of the GGGPuTTT(A)(C)A motif are recognized by lymphocyte specific factors. The latter motif is highly conserved between several lymphokine genes and is therefore designated as a T cell element (TCE). In E14 T cells, pentamers of the distal TCE(d) confer an activity similar to that of the entire IL-2 enhancer, whereas in B and HeLa cells, the TCE(d)-pentamer is inactive as is the IL-2 enhancer. These data indicate the involvement of the TCE(d) and its recognition factor(s) in the cell type specific induction of the IL-2 gene during T cell activation.