title: Grb14 is a negative regulator of CEACAM3-mediated phagocytosis of pathogenic bacteria.
abstract: Carcinoembryonic antigen-related cell adhesion molecule 3 (CEACAM3) is a phagocytic receptor on human granulocytes, which mediates the opsonin-independent recognition and internalization of a restricted set of Gram-negative bacteria such as Neisseria gonorrhoeae. In an unbiased screen using a SH2 domain microarray we identified the SH2 domain of growth factor receptor-bound protein 14 (Grb14) as a novel binding partner of CEACAM3. Biochemical assays and microscopic studies demonstrated that the Grb14 SH2 domain promoted the rapid recruitment of this adaptor protein to the immunoreceptor-based activation motif (ITAM)-like sequence within the cytoplasmic domain of CEACAM3. Furthermore, FRET-FLIM analyses confirmed the direct association of Grb14 and CEACAM3 in intact cells at the sites of bacteria-host cell contact. Knockdown of endogenous Grb14 by RNA interference as well as Grb14 overexpression indicate an inhibitory role for this adapter protein in CEACAM3-mediated phagocytosis. Therefore, Grb14 is the first negative regulator of CEACAM3-initiated bacterial phagocytosis and might help to focus granulocyte responses to the subcellular sites of pathogen-host cell contact.
authors.affiliation: Lehrstuhl Zellbiologie, Universität Konstanz, 78457 Konstanz, Germany.
authors.forename: Kathrin
authors.initials: K
authors.lastname: Kopp
authors.forename: Alexander
authors.initials: A
authors.lastname: Buntru
authors.forename: Stefan
authors.initials: S
authors.lastname: Pils
authors.forename: Timo
authors.initials: T
authors.lastname: Zimmermann
authors.forename: Ronald
authors.initials: R
authors.lastname: Frank
authors.forename: Andreas
authors.initials: A
authors.lastname: Zumbusch
authors.forename: Christof R
authors.initials: CR
authors.lastname: Hauck
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000502:physiology*; D002272:Carcinoembryonic Antigen / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods; D006098:Granulocytes / Q000166:cytology; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D009344:Neisseria gonorrhoeae / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D010587:Phagocytosis; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000737:chemistry; D017434:Protein Structure, Tertiary; D014443:Tyrosine / Q000737:chemistry
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C075729:CEACAM3 protein, human; D002272:Carcinoembryonic Antigen; C099655:GRB14 protein, human; D019000:Phosphotyrosine; D014443:Tyrosine