title: Differential interaction of Crkl with Cbl or C3G, Hef-1, and gamma subunit immunoreceptor tyrosine-based activation motif in signaling of myeloid high affinity Fc receptor for IgG (Fc gamma RI).
abstract: Cbl-Crkl and Crkl-C3G interactions have been implicated in T cell and B cell receptor signaling and in the regulation of the small GTPase, Rap1. Recent evidence suggests that Rap1 plays a prominent role in the regulation of immunoreceptor tyrosine-based activation motif (ITAM) signaling. To gain insight into the role of Crkl in myeloid ITAM signaling, we investigated Cbl-Crkl and Crkl-C3G interactions following Fc gamma RI aggregation in U937IF cells. Fc gamma RI cross-linking of U937IF cells results in the tyrosine phosphorylation of Cbl, Crkl, and Hef-1, an increase in the association of Crkl with Cbl via direct SH2 domain interaction and increased Crkl-Hef-1 binding. Crkl constitutively binds to the guanine nucleotide-releasing protein, C3G, via direct SH3 domain binding. Our data show that distinct Cbl-Crkl and Crkl-C3G complexes exist in myeloid cells, suggesting that these complexes may modulate distinct signaling events. Anti-Crkl immunoprecipitations demonstrate that the ITAM-containing gamma subunit of Fc gamma RI is induced to form a complex with the Crkl protein, and Crkl binds to the cytoskeletal protein, Hef-1. The induced association of Crkl with Cbl, Hef-1, and Fc gamma RI gamma after Fc gamma RI activation and the constitutive association between C3G and Crkl provide the first evidence that a Fc gamma RI gamma-Crkl-C3G complex may link ITAM receptors to the activation of Rap1 in myeloid cells.
authors.affiliation: Division of Hematology-Oncology, Children's Hospital Los Angeles Research Institute, University of Southern California School of Medicine 90027, USA.
authors.forename: W T
authors.initials: WT
authors.lastname: Kyono
authors.forename: R
authors.initials: R
authors.lastname: de Jong
authors.forename: R K
authors.initials: RK
authors.lastname: Park
authors.forename: Y
authors.initials: Y
authors.lastname: Liu
authors.forename: N
authors.initials: N
authors.lastname: Heisterkamp
authors.forename: J
authors.initials: J
authors.lastname: Groffen
authors.forename: D L
authors.initials: DL
authors.lastname: Durden
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D020662:Guanine Nucleotide Exchange Factors; D006801:Humans; D008213:Lymphocyte Activation; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000276:immunology / Q000378:metabolism*; D010750:Phosphoproteins / Q000276:immunology / Q000378:metabolism*; D010766:Phosphorylation; D011506:Proteins / Q000276:immunology / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000276:immunology / Q000378:metabolism*; D016315:Proto-Oncogene Proteins c-abl / Q000378:metabolism; D050721:Proto-Oncogene Proteins c-cbl; D011940:Receptor Aggregation / Q000276:immunology; D017452:Receptors, IgG / Q000378:metabolism* / Q000502:physiology; D011971:Receptors, Immunologic / Q000378:metabolism*; D015398:Signal Transduction / Q000276:immunology*; D014443:Tyrosine / Q000378:metabolism*; D020298:U937 Cells; D044767:Ubiquitin-Protein Ligases; D018909:src Homology Domains / Q000276:immunology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C082869:CRKL protein; D020662:Guanine Nucleotide Exchange Factors; C099942:NEDD9 protein, human; D009687:Nuclear Proteins; D010750:Phosphoproteins; D011506:Proteins; D011518:Proto-Oncogene Proteins; D017452:Receptors, IgG; D011971:Receptors, Immunologic; D014443:Tyrosine; D050721:Proto-Oncogene Proteins c-cbl; D044767:Ubiquitin-Protein Ligases; D016315:Proto-Oncogene Proteins c-abl; C067419:CBL protein, human