TY - JOUR
T1 - Stimulatory killer Ig-like receptors modulate T cell activation through DAP12-dependent and DAP12-independent mechanisms
AU - Snyder, Melissa R.
AU - Nakajima, Takako
AU - Leibson, Paul J.
AU - Weyand, Cornelia M.
AU - Goronzy, Jörg J.
PY - 2004/9/15
Y1 - 2004/9/15
N2 - Stimulatory killer Ig-like receptors (KIRs) are expressed by various lymphocytes, including NK cells and subsets of T cells. In NK cells, KIRs associate with the adapter molecule KARAP/DAP12, which confers the ability to function as an independent activation unit. The function of KIRs and killer cell activating receptor-associated protein (KARAP)/DAP12 in T cells is unclear. By flow cytometry, we demonstrated that CD4+CD28null T cells heterogeneously express KIRs and/or KARAP/DAP12. In clones that lacked expression of KARAP/DAP12, the stimulatory KIR KIR2DS2 signaled through the JNK pathway, but did not activate the ERK pathway. However, in the presence of KARAP/DAP12, stimulation through KIR2DS2 led to phosphorylation of both JNK and ERK. Transfection experiments confirmed that KIR2DS2-mediated ERK phosphorylation was dependent on KARAP/DAP12. The differential signaling of IKR2DS2 through association with alternative adapter molecules resulted in differential regulation of cellular activity. In clones that lacked expression of KARAP/DAP12, stimulation of KIR2DS2 did not induce cytotoxicity. However, KIR2DS2 did augment suboptimal TCR stimulation, leading to enhanced IFN-γ production. In clones that expressed KARAP/DAP12, KIR2DS2 directly activated both cytotoxicity and IFN-γ production without the need for TCR-derived signals. The function of stimulatory KIRs in T cells is determined by the expression of the appropriate adapter molecule. Expression of KARAP/DAP12 is sufficient to convert a costimulatory KIR into a stimulatory molecule. These differing functions mediated by alternative signaling pathways have implications for the pathogenesis of diseases such as rheumatoid arthritis and acute coronary syndromes, in which aberrant expression of KIRs on T cells is frequently observed.
AB - Stimulatory killer Ig-like receptors (KIRs) are expressed by various lymphocytes, including NK cells and subsets of T cells. In NK cells, KIRs associate with the adapter molecule KARAP/DAP12, which confers the ability to function as an independent activation unit. The function of KIRs and killer cell activating receptor-associated protein (KARAP)/DAP12 in T cells is unclear. By flow cytometry, we demonstrated that CD4+CD28null T cells heterogeneously express KIRs and/or KARAP/DAP12. In clones that lacked expression of KARAP/DAP12, the stimulatory KIR KIR2DS2 signaled through the JNK pathway, but did not activate the ERK pathway. However, in the presence of KARAP/DAP12, stimulation through KIR2DS2 led to phosphorylation of both JNK and ERK. Transfection experiments confirmed that KIR2DS2-mediated ERK phosphorylation was dependent on KARAP/DAP12. The differential signaling of IKR2DS2 through association with alternative adapter molecules resulted in differential regulation of cellular activity. In clones that lacked expression of KARAP/DAP12, stimulation of KIR2DS2 did not induce cytotoxicity. However, KIR2DS2 did augment suboptimal TCR stimulation, leading to enhanced IFN-γ production. In clones that expressed KARAP/DAP12, KIR2DS2 directly activated both cytotoxicity and IFN-γ production without the need for TCR-derived signals. The function of stimulatory KIRs in T cells is determined by the expression of the appropriate adapter molecule. Expression of KARAP/DAP12 is sufficient to convert a costimulatory KIR into a stimulatory molecule. These differing functions mediated by alternative signaling pathways have implications for the pathogenesis of diseases such as rheumatoid arthritis and acute coronary syndromes, in which aberrant expression of KIRs on T cells is frequently observed.
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U2 - 10.4049/jimmunol.173.6.3725
DO - 10.4049/jimmunol.173.6.3725
M3 - Article
C2 - 15356118
AN - SCOPUS:4644239414
SN - 0022-1767
VL - 173
SP - 3725
EP - 3731
JO - Journal of Immunology
JF - Journal of Immunology
IS - 6
ER -