Transcription of the interleukin 4 gene is regulated by multiple promoter elements.

Abstract

SummaryActivation of T helper cell 1 (Thl) and Th2 results in transcription of the interleukin 2 (IL-2) and IL-4 cytokine genes, respectively. Whereas many of the regulatory elements and factors responsible for IL-2 transcription in T cells are well defined, little is known about parallel mechanisms that drive transcription of the IL-4 gene. Here we have analyzed the murine IL-4 promoter, both in vivo and in a Th2 clone. 3 kh of IL-4 upstream sequence is shown to be sufficient to achieve tissue-specific and inducible expression of a thymidine kinase reporter gene in vivo in a manner that mirrors the expression of endogenous IL-4. Tissue-specific and inducible expression is also demonstrated in a Th2 done, but not in a B cell line. Deletional and mutational analysis of the IL-4 promoter demonstrated that sequences from -100 to -28 were necessary for a transcriptional response to Concanavalin A or anti-CD3 monoclonal antibody. An overlapping, yet smaller region, spanning the sequences from -60 to -28 bp was shown to be required for the response to ionomycin. Mutation of an 8-bp region from -43 to -35 of the IL-4 promoter completely abrogated IL-4 gene transcription in response to all stimuli tested. In addition, our results show that the effects of the immunosuppressive agent Cyclosporin A map to the same DNA sequences as the positive control elements. These results identify DNA sequences that are functionally important for the control of IL-4 gene transcription both in vivo and in vitro. Although these sequences are highly conserved in the human and murine IL-4 genes, they are largely not present in the IL-2 enhancer complex. Thus, cytokine-specific cis-acting elements may be one mechanism by which these two cytokine genes are differentially regulated.

Glucocorticoids Inhibit Calcium- and Calcineurin-Dependent Activation of the Human IL-4 Promoter

“…1 shows the results of experiments using a full-length promoter construct that contains 372 bp of the IL-4 promoter linked to the firefly luciferase gene (pLuc 372). As we and others have previously observed with different IL-4 promoter constructs (26,39), pLuc 372 was maximally inducible with a calcium signal alone. Promoter activity was not affected by Dex alone, consistent with the negligible expression of nuclear GR protein in these cells.…”

“…In T cells, IL-4 expression is tightly controlled at the level of transcription by multiple regulatory elements located within a proximal promoter region (23)(24)(25)(26)(27)(28)(29)(30). Regulatory elements outside of the promoter have also been detected (31,32).…”

“…Unlike the IL-2 promoter, which requires costimulation of calcium-and protein kinase C (PKC)-mediated signaling pathways for full activation, the IL-4 promoter can be maximally induced by a calcium signal alone (26,39,40). A constitutively active mutant of the calcium-sensitive phosphatase calcineurin (CN) can efficiently substitute for this signal (40 -42).…”

Mercuric chloride, a chemical responsible for T helper cell (Th)2-mediated autoimmunity in brown Norway rats, directly triggers T cells to produce interleukin-4.

“…One may therefore conclude that, although Th2 cytokines could not be detected in the culture supernatants, HgCl2 induced IL-4 production by BN rat spleen cells. Incidentally, our study showed for the first time, using cross-reacting (44). HgCl2 could also act on cell-surface determinant in a way similar to anti-CD3 mAb (42) or, as already suggested (13), affect membrane determinants such as adhesion molecules (45), resulting in increased cell interactions.…”

Vav Synergizes with Protein Kinase CΘ to Mediate IL-4 Gene Expression in Response to CD28 Costimulation in T Cells

“…The IL-4 promoter harbors several purine-rich motifs, the so-called P elements, that are critical for lymphocyte activation-induced transcription (12)(13)(14)(15)(16)(17). These sites, termed P0, P1, P2, P3, and P4, contain sequences that bind several distinct transcription factors, including members of the NF-AT family.…”