Interaction of suppressor of cytokine signaling 2 with phosphorylated Pyk2 regulates human NK cell function (113.1)

Abstract

Abstract Natural killer cells are large granular lymphocytes that play an important role in innate immunity, contributing to the elimination of tumor or virus-infected cells. Resting NK cells, however, have only minimal cytolytic activity and secrete a low level of IFN-γ. The cytokine IL-15 can promote the expression of effectors in NK cells. In this study, we demonstrate that suppressor of cytokine signaling 2(SOCS2) has a novel role in IL-15-primed human NK cell function. SOCS2 expression was upregulated in NK cells following stimulation with IL-15. During IL-15 mediated NK cell priming, SOCS2 interacted with phosphorylated proline-rich tyrosine kinase 2(Pyk2) at tyrosine 402(p-Pyk2Tyr402) and induced the proteasome-mediated degradation of p-Pyk2Tyr402 via ubiquitination. Knockdown of SOCS2 resulted in the accumulation of p-Pyk2Tyr402 and blocked NK cell effector functions. In addition, NK cell cytolytic activity and IFN-γ production were inhibited by over-expression of the wild-type of Pyk2 but not by the over-expression of tyrosine 402 mutant of Pyk2. These results suggest that SOCS2 regulates human NK cell effector functions via control of phosphorylated Pyk2 depending on IL-15 existence.