Signal-Transducing Adaptor Protein-2 Controls the IgE-Mediated, Mast Cell-Mediated Anaphylactic Responses

Signal-transducing adaptor protein-2 (STAP-2) is a recently identified adaptor protein that regulates immune and inflammatory responses through interactions with a variety of signaling and transcriptional molecules. In the current study, we clarified the physiological role of STAP-2 in mast cell function, a key mediator of IgE-associated allergic responses. STAP-2 is constitutively expressed in mast cells. STAP-2 deficiency in mast cells greatly enhances Fc epsilon RI-mediated signals, resulting in the increased tyrosine phosphorylation of the phospholipase C-g isoform, calcium mobilization, and degranulation. Of importance, STAP-2-deficient mice challenged with DNP-BSA after passive sensitization with anti-DNP IgE show more severe rectal temperature decrease than do wild-type mice. STAP-2-deficient mice also show increased vascular permeability and more severe cutaneous anaphylaxis after DNP-BSA injection. These regulatory functions performed by STAP-2 indicate that there is an interaction between STAP-2 and Fc epsilon RI. In addition, our previous data indicate that STAP-2 binds to the phospholipase C-gamma isoform and I kappa B kinase-beta. Therefore, our data described in this article strongly suggest that manipulation of STAP-2 expression in mast cells may control the pathogenesis of allergic diseases and have the potential for treating patients with allergy.