A DAP12-mediated pathway regulates expression of CC chemokine receptor 7 and maturation of human dendritic cells

Gene targeting of the adaptor molecule DAP12 in mice caused abnormal distri bution and impaired antigen presentation capacity of dendritic cells (DCs). However, the DAP12-associated receptors expressed on DCs and their functio ns have not been identified yet. Here we show that the triggering receptor expressed on myeloid cells-2 (TREM-2) is a cell surface receptor on human m onocyte-derived DCs, which is associated with DAP12. TREM-2/DAP12 promotes upregulation of CC chemokine receptor 7, partial DC maturation, and DC surv ival through activation of protein tyrosine kinases and extracellular signa l-regulated kinase. In contrast to Toll-like receptor-mediated signaling, T REM2/DAP12 stimulation is independent of nuclear factor-kappaB and p38 stre ss-activated protein kinase. This novel DC activation pathway may regulate DC homeostasis. and amplify DC responses to pathogens, explaining the pheno type observed in DAP12-deficient mice.