Murine CD4+CD25+ regulatory T cells fail to undergo chromatin remodeling across the proximal promoter region of the IL-2 gene.
CD4+CD25+ regulatory T cells (Treg) acquire unique immunosuppressive properties while maintaining an anergy phenotype when activated in vitro under conditions that induce IL-2 production and proliferation in conventional CD4+ T cells. We investigated the mechanism underlying one component of this naturally anergic phenotype, the inability of the Treg cells to produce IL-2 following activation. Analysis of freshly isolated murine CD4+CD25+ Treg and conventional CD4+CD25- T cells following PMA/ionomycin stimulation demonstrated no differences in inducible AP-1 formation, an important transcriptional complex in regulating IL-2 gene expression. Although p38 MAPK and ERK1/2 protein kinases were phosphorylated with similar kinetics, we observed diminished activation of JNK in the CD4+CD25+ Treg cells. However, lentiviral-mediated reconstitution of the JNK pathway using a constitutively active construct did not overcome the block in IL-2 synthesis. Using a PCR-based chromatin accessibility assay we found that the minimal IL-2 promoter region of CD4+CD25+ Treg cells, unlike conventional CD4 T cells, did not undergo chromatin remodeling following stimulation, suggesting that the inability of CD4+CD25+ Treg cells to secrete IL-2 following activation is controlled at the chromatin level.
Su
Leon
L
Division of Immunology and Rheumatology, Department of Medicine, Stanford University, CA 94305, USA.
Creusot
Remi J
RJ
Gallo
Elena M
EM
Chan
Steven M
SM
Utz
Paul J
PJ
Fathman
C Garrison
CG
Ermann
Joerg
J
D000818:Animals; D015704:CD4 Antigens / Q000032:analysis*; D007108:Immune Tolerance; D007376:Interleukin-2 / Q000096:biosynthesis / Q000235:genetics*; D048031:JNK Mitogen-Activated Protein Kinases; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism / Q000502:physiology; D011401:Promoter Regions, Genetic; D015375:Receptors, Interleukin-2 / Q000032:analysis*; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000378:metabolism*; D018808:Transcription Factor AP-1 / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases
D015704:CD4 Antigens; D007376:Interleukin-2; D015375:Receptors, Interleukin-2; D018808:Transcription Factor AP-1; D048031:JNK Mitogen-Activated Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases