The inhibitory effect of immunoreceptor tyrosine-based activation motif (ITAM)-containing adapters DAP12 and FcεRI γ-chain (FcRγ) has been found in many immune functions. Herein, we have further explored the role of these adapters in
C-type lectin receptors response. We identified that FcRγ, but not DAP12, could negatively regulate the
Dectin-1 responses in dendritic cells (DCs). Loss of FcRγ or both DAP12 and FcRγ enhanced the maturation and
cytokine production in DCs upon
Dectin-1 activation compared to normal cells, whereas DCs lacking only DAP12 showed little changes. In addition, increments of T cell activation and T helper 17 polarization induced by FcRγ-deficient DCs were observed both in vitro and in vivo. Examining the
Dectin-1 signaling, we revealed that the activations of several signaling molecules were augmented in FcRγ-deficient DCs stimulated with
Dectin-1 ligands. Furthermore, we demonstrated that the association of
phosphatases SHP-1 and PTEN with FcRγ may contribute to the negative regulation of FcRγ in
Dectin-1 activation in DCs. These results extend the inhibitory effect of ITAM-containing adapters to
Dectin-1 response in immune functions, even though
Dectin-1 contains an ITAM-like intracellular domain. According to the role of
Dectin-1 in responding to microbes and
tumor cells, our finding may have applications in the development of
vaccine and
cancer therapy.