Differential activation of T cell cytokine production by the extracellular signal-regulated kinase (ERK) signaling pathway.
Stimulation of T cells via the T cell receptor (TCR) activates a number of signaling pathways that are potentially involved in the elicitation of physiological responses, such as the production of cytokines. The extracellular signal-regulated kinases (ERK) are a group of molecules activated in response to TCR ligation, whose role in T cell cytokine production is controversial. In this study, we have asked whether ERK activation is coupled to the production of a number of T cell-derived cytokines, and whether particular cytokines are differentially affected by ERK activation. To address these questions, we have utilized a constitutively active version of the immediate upstream activator of both ERK1 and ERK2, mitogen-activated/extracellular signal-regulated kinase 1 (MEK1), to activate ERK signaling selectively in the absence of other TCR-activated signaling pathways. The effect of constitutive MEK/ERK activation on T cell cytokine production was measured by transiently co-transfecting newly activated mouse T cells with DNA encoding constitutively active MEK1 (CA-MEK1) and the human interleukin-2 (IL-2) receptor alpha chain (hCD25), purifying hCD25+ transfectants by flow-cytometric cell sorting, and measuring the production of IL-3, IL-4, interferon (IFN)-gamma and granulocyte/macrophage-colony-stimulating factor (GM-CSF) either in the presence or absence of ionomycin stimulation. Newly activated T cells were used in these experiments as they more closely resemble T cells activated in vivo than do transformed T cells or long-term established T cell clones. CA-MEK1 expression led to constitutive ERK activation, which acted synergystically with ionomycin treatment to stimulate cytokine production. Furthermore, these experiments revealed a hierarchy of cytokine responsiveness to MEK/ERK activation, such that the production of IL-3 was most affected, followed by GM-CSF, IFN-gamma, and IL-4.
Transplantation Biology Unit, Queensland Institute of Medical Research, Brisbane, Australia. markE@qimr.edu.au
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M
Egerton
D R
DR
Fitzpatrick
A D
AD
Catling
A
A
Kelso
D000818:Animals; D002118:Calcium / Q000502:physiology; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000502:physiology*; D002469:Cell Separation; D002478:Cells, Cultured; D016207:Cytokines / Q000096:biosynthesis* / Q000235:genetics; D005786:Gene Expression Regulation; D006801:Humans; D008213:Lymphocyte Activation; D048369:MAP Kinase Kinase 1; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020929:Mitogen-Activated Protein Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D011505:Protein-Tyrosine Kinases / Q000502:physiology*; D015375:Receptors, Interleukin-2 / Q000502:physiology; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000502:physiology*
D016207:Cytokines; D015375:Receptors, Interleukin-2; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; C482125:MAP2K1 protein, human; C482127:Map2k1 protein, mouse; D020929:Mitogen-Activated Protein Kinase Kinases; D002118:Calcium