Abstract
Signaling through the TCR and costimulatory signals primarily control transcription of the IL-2 gene in naive T cells. The minimal promoter necessary for this expression lies proximal, between -300 and the transcription start site. We had previously shown that activation of the arylhydrocarbon receptor (AHR), a member of the bHLH-PAS family of transcription factors, leads to increased mRNA expression of IL-2 in murine fetal thymocytes. The AHR is abundant in the thymus and may play a role for the development of the immune system. Moreover, its overactivation by chemicals such as dioxins leads to immunosuppression and thymic involution. Binding motifs for the liganded AHR can be identified in the distal region -1300 to -800 of the mouse IL-2 promoter. We show here that these DNA motifs, the so-called dioxin response elements, after binding to the liganded AHR are sufficient to transactivate luciferase expression in a reporter gene system. The IL-2 gene can be induced by the AHR also in thymocytes in vivo after injection of 2,3,7, 8-tetrachlorodibenzo-p-dioxin, a potent ligand of the AHR. The AHR mediates the IL-2 induction as shown with AHR-deficient mice. However, in spleen cells in vitro costimulation via the TCR is necessary for optimal IL-2 gene induction. Thus, the IL-2 promoter region contains novel distal regulatory elements that can be addressed by the AHR to induce IL-2 and can cooperate with the proximal promoter in this.
Publication types
-
Research Support, Non-U.S. Gov't
MeSH terms
-
Animals
-
Basic Helix-Loop-Helix Transcription Factors
-
CD3 Complex / immunology
-
Cell Differentiation / drug effects
-
Cell Differentiation / immunology
-
Cells, Cultured
-
Conserved Sequence
-
Enhancer Elements, Genetic / drug effects
-
Enhancer Elements, Genetic / immunology
-
Evolution, Molecular
-
Female
-
Helix-Loop-Helix Motifs / immunology
-
Immune Sera / physiology
-
Injections, Intraperitoneal
-
Interleukin-2 / biosynthesis
-
Interleukin-2 / genetics*
-
Interleukin-2 / metabolism*
-
Lymphocyte Activation / drug effects
-
Male
-
Mice
-
Mice, Inbred C57BL
-
Mice, Knockout
-
Multigene Family / immunology
-
Organ Culture Techniques
-
Polychlorinated Dibenzodioxins / administration & dosage
-
Polychlorinated Dibenzodioxins / metabolism
-
Polychlorinated Dibenzodioxins / pharmacology
-
Promoter Regions, Genetic / drug effects
-
Promoter Regions, Genetic / immunology*
-
RNA, Messenger / biosynthesis
-
Receptors, Aryl Hydrocarbon / metabolism
-
Receptors, Aryl Hydrocarbon / physiology*
-
Response Elements / drug effects
-
Response Elements / immunology*
-
Signal Transduction / immunology
-
Spleen / cytology
-
Spleen / drug effects
-
Spleen / immunology
-
Spleen / metabolism
-
T-Lymphocytes / cytology
-
T-Lymphocytes / drug effects
-
T-Lymphocytes / immunology
-
T-Lymphocytes / metabolism
-
Trans-Activators / physiology*
Substances
-
Basic Helix-Loop-Helix Transcription Factors
-
CD3 Complex
-
Immune Sera
-
Interleukin-2
-
Polychlorinated Dibenzodioxins
-
RNA, Messenger
-
Receptors, Aryl Hydrocarbon
-
Trans-Activators
-
endothelial PAS domain-containing protein 1