title: The granulocyte receptor carcinoembryonic antigen-related cell adhesion molecule 3 (CEACAM3) directly associates with Vav to promote phagocytosis of human pathogens.
abstract: The human granulocyte-specific receptor carcinoembryonic antigen-related cell adhesion molecule (CEACAM)3 is critically involved in the opsonin-independent recognition of several bacterial pathogens. CEACAM3-mediated phagocytosis depends on the integrity of an ITAM-like sequence within the cytoplasmic domain of CEACAM3 and is characterized by rapid stimulation of the GTPase Rac. By performing a functional screen with CEACAM3-expressing cells, we found that overexpression of a dominant-negative form of the guanine nucleotide exchange factor Vav, but not the dominant-negative versions SWAP70, Dock2, or ELMO1 interfered with CEACAM3-initiated phagocytosis. Moreover, small interfering RNA-mediated silencing of Vav reduced uptake and abrogated the stimulation of Rac in response to bacterial CEACAM3 engagement. In Vav1/Vav2-deficient cells, CEACAM3-mediated internalization was only observed after re-expression of Vav. Vav colocalized with CEACAM3 upon bacterial infection, coimmunoprecipitated in a complex with CEACAM3, and the Vav Src homology 2 domain directly associated with phosphorylated Tyr(230) of CEACAM3. In primary human granulocytes, TAT-mediated transduction of dominant-negative Vav, but not SWAP70, severely impaired the uptake of CEACAM3-binding bacteria. These data support the view that, different from canonical ITAM signaling, the CEACAM3 ITAM-like sequence short-wires bacterial recognition and Rac stimulation via a direct association with Vav to promote rapid phagocytosis and elimination of CEACAM-binding human pathogens.
authors.affiliation: Zentrum für Infektionsforschung, Universität Würzburg, Würzburg, Germany.
authors.forename: Tim
authors.initials: T
authors.lastname: Schmitter
authors.forename: Stefan
authors.initials: S
authors.lastname: Pils
authors.forename: Vadim
authors.initials: V
authors.lastname: Sakk
authors.forename: Ronald
authors.initials: R
authors.lastname: Frank
authors.forename: Klaus-Dieter
authors.initials: KD
authors.lastname: Fischer
authors.forename: Christof R
authors.initials: CR
authors.lastname: Hauck
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000276:immunology; D002272:Carcinoembryonic Antigen / Q000276:immunology*; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000235:genetics / Q000276:immunology; D020690:GTPase-Activating Proteins; D020868:Gene Silencing; D006098:Granulocytes / Q000166:cytology / Q000276:immunology*; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000276:immunology; D015778:Minor Histocompatibility Antigens; D009344:Neisseria gonorrhoeae / Q000235:genetics / Q000276:immunology*; D009687:Nuclear Proteins / Q000235:genetics / Q000276:immunology; D010587:Phagocytosis / Q000235:genetics / Q000276:immunology*; D051567:Proto-Oncogene Proteins c-vav / Q000172:deficiency / Q000276:immunology*; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology; D018909:src Homology Domains / Q000235:genetics / Q000276:immunology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C075729:CEACAM3 protein, human; D002272:Carcinoembryonic Antigen; D004268:DNA-Binding Proteins; C402110:DOCK2 protein, human; C465214:ELMO1 protein, human; D020690:GTPase-Activating Proteins; D020662:Guanine Nucleotide Exchange Factors; D015778:Minor Histocompatibility Antigens; D009687:Nuclear Proteins; D051567:Proto-Oncogene Proteins c-vav; D034741:RNA, Small Interfering; C491873:SWAP70 protein, human; C496618:VAV1 protein, human; C093651:VAV2 protein, human