Suppression of T-cell responsiveness by inducible cAMP early repressor (ICER).
Depending on the nature of the costimulation of T lymphocytes, expression of regulatory cytokines and chemokines is either susceptible or resistant to cyclic AMP (cAMP)-mediated inhibition. Our data show that cAMP-mediated inhibition of endogenously expressed cytokines, which is characteristic for T helper (Th) 1- and Th 2-like phenotypes, correlates with the induction of a potent transcriptional repressor, inducible cAMP early repressor (ICER), in both subsets of T cells activated under conditions of suboptimal interleukin-2 (IL-2) expression. Importantly, Th-specific expression of certain chemokines is also susceptible to cAMP-mediated transcriptional attenuation. To determine whether ICER per se, rather than forskolin-mediated elevation of intracellular cAMP, is responsible for the observed inhibitory effect, we generated transgenic mice expressing ICER under the control of a lymphocyte-specific lck promoter. On stimulation, transgenic thymocytes overexpressing ICER exhibited reduced levels of IL-2 and interferon (IFN)-gamma and failed to express the macrophage inflammatory protein (MIP)-1alpha and MIP-1beta genes. Splenic T cells from ICER-transgenic mice showed a defect in proliferation and lacked a mixed lymphocyte reaction response, implying that ICER-mediated inhibition of cytokine and chemokine expression might play an important role in T-cell inactivation.
Bodor
J
J
Experimental Immunology Branch, Division of Basic Sciences, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
Feigenbaum
L
L
Bodorova
J
J
Bare
C
C
Reitz
M S
MS
Gress
R E
RE
D000818:Animals; D002455:Cell Division / Q000187:drug effects; D018925:Chemokines / Q000096:biosynthesis / Q000235:genetics; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000494:pharmacology*; D051786:Cyclic AMP Response Element Modulator; D016207:Cytokines / Q000096:biosynthesis* / Q000235:genetics; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D015232:Dinoprostone / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis / Q000235:genetics; D007376:Interleukin-2 / Q000096:biosynthesis / Q000235:genetics; D015759:Ionomycin / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects; D007959:Lymphocyte Culture Test, Mixed; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins; D015290:Second Messenger Systems / Q000187:drug effects / Q000502:physiology; D013154:Spleen / Q000166:cytology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D018417:Th1 Cells / Q000187:drug effects* / Q000378:metabolism; D018418:Th2 Cells / Q000187:drug effects* / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects
D018925:Chemokines; D016207:Cytokines; D004268:DNA-Binding Proteins; D007376:Interleukin-2; D012097:Repressor Proteins; D051786:Cyclic AMP Response Element Modulator; D005576:Colforsin; D015759:Ionomycin; D007371:Interferon-gamma; D000242:Cyclic AMP; D015232:Dinoprostone; D013755:Tetradecanoylphorbol Acetate