International Immunology Advance Access originally published online on February 16, 2007
International Immunology 2007 19(4):401-409; doi:10.1093/intimm/dxm005
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CD160-activating NK cell effector functions depend on the phosphatidylinositol 3-kinase recruitment
1 Institut National de la Santé et de la Recherche Médicale Unité 563 and Université Paul Sabatier de Toulouse, Hôpital Purpan, 31024 Toulouse Cedex 3, France
2 Institut National de la Santé et de la Recherche Médicale Unité 841, Faculté de Médecine de Créteil, 94010 Créteil Cedex, France
Correspondence to: A. Bensussan; E-mail: armand.bensussan{at}creteil.inserm.fr
CD160 NK cell-activating receptor is a glycosyl-phosphatidylinositol-anchored molecule that, upon specific engagement, triggers both cytotoxicity and a unique cytokine production [IFN-
, tumor necrosis factor-
(TNF-) and IL-6] through an undefined signaling pathway. In the current study, we have identified several signaling molecules recruited after mAb-specific CD160 engagement in freshly isolated human circulating NK cells. Using confocal microscopy, we found that CD160 engagement induces the recruitment and co-localization of phosphorylated molecules with redistributed, capped CD160 at the cell surface. We then demonstrated that phosphatidylinositol 3-kinase (PI3K) signaling molecule is required for CD160-mediated cytotoxicity and cytokine release. First, we observed by confocal microscopy that engagement of CD160 induces its polarization and co-localization with PI3K. Second, we showed that pharmacological inhibitors of PI3K abrogate both CD160-mediated cytotoxicity and IFN-, TNF- and IL-6 cytokine release. We further found that CD160 engagement induced marked phosphorylation of Akt, as evidenced by western blotting. We identified additional CD160-mediated signaling molecules recruited downstream and upstream of PI3K. Both induction of phosphorylated ERK molecules after CD160-specific engagement and prevention of CD160-induced cytokine release by MEK pharmacological inhibitor indicate that ERK downstream pathway is implicated. Similarly, we identified that Syk molecule upstream of PI3K is involved in the signaling cascade mediated by CD160 engagement. Two different Syk-specific inhibitors blocked CD160-mediated cytokine release, and CD160-specific engagement induced the enhancement of phosphorylated Syk proteins. These data demonstrate that PI3K is a crucial signaling element for both effector functions of the CD160 NK cell-activating receptor.
Keywords: cytokine, innate immunity, signaling pathway
* These authors are co-senior authors.
Transmitting editor: T. F. Tedder
Received 5 October 2006, accepted 15 January 2007.
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