Impaired CD28-mediated interleukin 2 production and proliferation in stress kinase SAPK/ERK1 kinase (SEK1)/mitogen-activated protein kinase kinase 4 (MKK4)-deficient T lymphocytes.
The dual specific kinase SAPK/ERK1 kinase (SEK1; mitogen-activated protein kinase kinase 4/Jun NH2 terminal kinase [ JNK] kinase) is a direct activator of stress-activated protein kinases ([SAPKs]/JNKs) in response to CD28 costimulation, CD40 signaling, or activation of the germinal center kinase. Here we show that SEK1(-/-) recombination-activating gene (RAG)2(-/-) chimeric mice have a partial block in B cell maturation. However, peripheral B cells displayed normal responses to IL-4, IgM, and CD40 cross-linking. SEK1(-/-) peripheral T cells showed decreased proliferation and IL-2 production after CD28 costimulation and PMA/Ca2+ ionophore activation. Although CD28 expression was absolutely crucial to generate vesicular stomatitis virus (VSV)-specific germinal centers, SEK1(-/-)RAG2(-/-) chimeras mounted a protective antiviral B cell response, exhibited normal IgG class switching, and made germinal centers in response to VSV. Interestingly, PMA/Ca2+ ionophore stimulation, which mimics TCR-CD3 and CD28-mediated signal transduction, induced SAPK/JNK activation in peripheral T cells, but not in thymocytes, from SEK1(-/-) mice. These results show that signaling pathways for SAPK activation are developmentally regulated in T cells. Although SEK1(-/-) thymocytes failed to induce SAPK/JNK in response to PMA/Ca2+ ionophore, SEK1(-/-)RAG2(-/-) thymocytes proliferated and made IL-2 after PMA/Ca2+ ionophore and CD3/CD28 stimulation, albeit at significantly lower levels compared to SEK1(+/+)RAG2(-/-) thymocytes, implying that CD28 costimulation and PMA/Ca2+ ionophore-triggered signaling pathways exist that can mediate proliferation and IL-2 production independently of SAPK activation. Our data provide the first genetic evidence that SEK1 is an important effector molecule that relays CD28 signaling to IL-2 production and T cell proliferation.
Nishina
H
H
Amgen Institute and Ontario Cancer Institute, Department of Medical Biophysics and Immunology, University of Toronto, M5G 2C1 Toronto, Ontario, Canada.
Bachmann
M
M
Oliveira-dos-Santos
A J
AJ
Kozieradzki
I
I
Fischer
K D
KD
Odermatt
B
B
Wakeham
A
A
Shahinian
A
A
Takimoto
H
H
Bernstein
A
A
Mak
T W
TW
Woodgett
J R
JR
Ohashi
P S
PS
Penninger
J M
JM
D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology / Q000201:enzymology / Q000276:immunology; D001483:Base Sequence; D018106:CD28 Antigens / Q000378:metabolism*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002454:Cell Differentiation; D002678:Chimera; D017931:DNA Primers / Q000235:genetics; D018858:Germinal Center / Q000166:cytology / Q000276:immunology; D007134:Immunoglobulin Switch Region; D007376:Interleukin-2 / Q000096:biosynthesis*; D048031:JNK Mitogen-Activated Protein Kinases; D008213:Lymphocyte Activation; D048670:MAP Kinase Kinase 4; D051379:Mice; D018345:Mice, Knockout; D020929:Mitogen-Activated Protein Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D016133:Polymerase Chain Reaction; D011494:Protein Kinases / Q000172:deficiency* / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000172:deficiency* / Q000235:genetics; D011505:Protein-Tyrosine Kinases / Q000172:deficiency* / Q000235:genetics; D011995:Recombination, Genetic; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000201:enzymology* / Q000276:immunology*; D014721:Vesicular stomatitis Indiana virus / Q000276:immunology / Q000472:pathogenicity
D018106:CD28 Antigens; D017931:DNA Primers; D007376:Interleukin-2; D011494:Protein Kinases; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; C482562:Map2k4 protein, mouse; D020929:Mitogen-Activated Protein Kinase Kinases