The GABP-responsive element of the interleukin-2 enhancer is regulated by JNK/SAPK-activating pathways in T lymphocytes.
T cell activation leads via multiple intracellular signaling pathways to rapid induction of interleukin-2 (IL-2) expression, which can be mimicked by costimulation with 12-O-tetradecanoylphorbol-13-acetate (TPA) and ionomycin. We have identified a distal IL-2 enhancer regulated by the Raf-MEK-ERK signaling pathway, which can be induced by TPA/ionomycin treatment. It contains a dyad symmetry element (DSE) controlled by the Ets-like transcription factor GA-binding protein (GABP), a target of activated ERK. TPA/ionomycin treatment of T cells stimulates both mitogen-activated ERK, as well as the stress-activated mitogen-activated protein kinase family members JNK/SAPK and p38. In this study, we investigated the contribution of the stress-activated pathways to the induction of the distal IL-2 enhancer. We show that JNK- but not p38-activating pathways regulate the DSE activity. Furthermore, the JNK/SAPK signaling pathway cooperates with the Raf-MEK-ERK cascade in TPA/ionomycin-induced DSE activity. In T cells, overexpression of SPRK/MLK3, an activator of JNK/SAPK, strongly induces DSE-dependent transcription and dominant negative kinases of SEK and SAPK impair TPA/ionomycin-induced DSE activity. Blocking both ERK and JNK/SAPK pathways abolishes the DSE induction. The inducibility of the DSE is strongly dependent on the Ets-core motifs, which are bound by GABP. Both subunits of GABP are phosphorylated upon JNK activation in vivo and three different isoforms of JNK/SAPK, but not p38, in vitro. Our data suggest that GABP is targeted by signaling events from both ERK and JNK/SAPK pathways. GABP therefore is a candidate for signal integration and regulation of IL-2 transcription in T lymphocytes.
Hoffmeyer
A
A
Institut für Medizinische Strahlenkunde und Zellforschung (MSZ), Universität Würzburg, Versbacher Strasse 5, D-97078 Würzburg, Germany.
Avots
A
A
Flory
E
E
Weber
C K
CK
Serfling
E
E
Rapp
U R
UR
D016475:3T3 Cells; D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004742:Enhancer Elements, Genetic; D004789:Enzyme Activation; D051268:GA-Binding Protein Transcription Factor; D006801:Humans; D007376:Interleukin-2 / Q000235:genetics*; D015759:Ionomycin / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases; D020930:MAP Kinase Kinase Kinases; D051379:Mice; D020928:Mitogen-Activated Protein Kinases; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D013601:T-Lymphocytes / Q000201:enzymology*; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured; D000097767:Mitogen-Activated Protein Kinase Kinase Kinase 11
D017871:Calcium-Calmodulin-Dependent Protein Kinases; D004268:DNA-Binding Proteins; D051268:GA-Binding Protein Transcription Factor; D007376:Interleukin-2; D015759:Ionomycin; D048031:JNK Mitogen-Activated Protein Kinases; D020930:MAP Kinase Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D017346:Protein Serine-Threonine Kinases; D014157:Transcription Factors; D000097767:Mitogen-Activated Protein Kinase Kinase Kinase 11