CD2AP/SHIP1 complex positively regulates plasmacytoid dendritic cell receptor signaling by inhibiting the E3 ubiquitin ligase Cbl.

ABSTRACT: The human plasmacytoid dendritic cell (pDC) receptor BDCA2 forms a complex with the adaptor Fc?R1? to activate an ITAM-signaling cascade. BDCA2 receptor signaling negatively regulates the TLR7/9-mediated type 1 IFN responses in pDCs, which may play a key role in controlling self-DNA/RNA-induced autoimmunity. We report in this article that CD2-associated adaptor protein (CD2AP), which is highly expressed in human pDCs, positively regulates BDCA2/Fc?R1? receptor signaling. By immunoprecipitation and mass spectrometry analyses, we found that CD2AP bound to SHIP1. Knockdown of CD2AP or SHIP1 reduced the BDCA2/Fc?R1?-mediated ITAM signaling and blocked its inhibition of TLR9-mediated type 1 IFN production. Knockdown of CD2AP or SHIP1 also enhanced the ubiquitination and degradation of Syk and Fc?R1? that was mediated by the E3 ubiquitin ligase Cbl. This led us to discover that, upon BDCA2 cross-linking, the CD2AP/SHIP1 complex associated with Cbl and inhibited its E3 ubiquitin ligase activity. In human primary pDCs, cross-linking of the BDCA2/Fc?R1? complex induced the recruitment of the CD2AP/SHIP1/Cbl complex to the plasma membrane of pDCs, where it colocalized with the BDCA2/Fc?R1? complex. Therefore, CD2AP positively regulates BDCA2/Fc?R1? signaling by forming a complex with SHIP1 to inhibit the E3 ubiquitin ligase Cbl.

SUBMITTER: Bao M 

PROVIDER: S-EPMC3665352 | biostudies-literature | 2012 Jul

REPOSITORIES: biostudies-literature