The microbial receptor CEACAM3 is linked to the calprotectin complex in granulocytes.
Engulfment of foreign pathogens is an evolutionary ancient host cell endocytic response. Signaling pathways effecting phagocytosis are divergent and largely depend on the structural features of the cell surface receptor utilized. CEACAM3, a member of the CD66 complex on human neutrophils, has been implicated as a cellular receptor promoting phagocytosis of microorganisms. The cytoplasmic domain of CEACAM3 (CEACAM3(cyt)) contains an immunoreceptor tyrosine-based activation motif. In this study we demonstrate that CEACAM3(cyt) is phosphorylated by protein kinase C, casein kinase I, and Src-kinase in vitro. To identify molecules binding to CEACAM3(cyt) in vivo, we used differentially phosphorylated recombinant expressed CEACAM cytoplasmic domains to isolate CEACAM3(cyt)-associated proteins from granulocyte extracts. Calprotectin, which modulates neutrophil integrin-mediated adhesion and leukocyte trafficking and displays antimicrobial activity, interacts specifically with CEACAM3(cyt). This interaction is calcium-modulated but independent of phosphorylation of CEACAM3(cyt). Although tyrosine-phosphorylated CEACAM3(cyt) binds and stimulates Src-kinases in vitro, no CEACAM3(cyt)-associated phosphokinase activity was copurified.
Streichert
T
T
Department of Surgery, University Hospital Eppendorf, Martinistrasse 52, 22046 Hamburg, Germany.
Ebrahimnejad
A
A
Ganzer
S
S
Flayeh
R
R
Wagener
C
C
Brümmer
J
J
D020013:Calcium Signaling; D002272:Carcinoembryonic Antigen / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D047388:Casein Kinases; D006098:Granulocytes / Q000382:microbiology* / Q000502:physiology*; D006801:Humans; D066298:In Vitro Techniques; D039841:Leukocyte L1 Antigen Complex; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019006:Neural Cell Adhesion Molecules / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010587:Phagocytosis; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity; D019061:src-Family Kinases / Q000378:metabolism
C075729:CEACAM3 protein, human; D002272:Carcinoembryonic Antigen; D039841:Leukocyte L1 Antigen Complex; D008562:Membrane Glycoproteins; D019006:Neural Cell Adhesion Molecules; D011994:Recombinant Proteins; D011494:Protein Kinases; D019061:src-Family Kinases; D047388:Casein Kinases; D011493:Protein Kinase C