title: Negative regulation of T cell antigen receptor-mediated Crk-L-C3G signaling and cell adhesion by Cbl-b.
abstract: It was previously reported that Cbl-b associates with Crk-L in Jurkat T cells. However, the physiological significance of such association remains unclear. Here we examined a regulatory role of Cbl-b in Crk-L-C3G signaling pathway. We found that Cbl-b associates with, and induces, ubiquitin conjugation to Crk-L, which requires a functional RING finger. Cbl-b deficiency does not affect Crk-L stability, but its association with C3G. In Cbl-b-/- T cells, the interaction between Crk-L and C3G, and the activity of the small GTPase Rap1, are increased. Cbl-b-/- T cells also display increased adhesion and cell surface binding to ICAM-1, a finding that is supported by the enhanced clustering of LFA-1 in Cbl-b-/- T cells in response to TCR stimulation. Thus, Cbl-b plays a negative role in Crk-L-C3G-mediated Rap1 and LFA-1 activation in T cells.
authors.affiliation: La Jolla Institute for Allergy and Immunology, San Diego, California 92121, USA.
authors.forename: Wenying
authors.initials: W
authors.lastname: Zhang
authors.forename: Yuan
authors.initials: Y
authors.lastname: Shao
authors.forename: Deyu
authors.initials: D
authors.lastname: Fang
authors.forename: Jianyong
authors.initials: J
authors.lastname: Huang
authors.forename: Myung-Shin
authors.initials: MS
authors.lastname: Jeon
authors.forename: Yun-Cai
authors.initials: YC
authors.lastname: Liu
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins / Q000378:metabolism / Q000502:physiology*; D002448:Cell Adhesion; D020735:Guanine Nucleotide-Releasing Factor 2 / Q000378:metabolism*; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D019169:Jurkat Cells; D008213:Lymphocyte Activation; D016169:Lymphocyte Function-Associated Antigen-1 / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism / Q000502:physiology*; D050721:Proto-Oncogene Proteins c-cbl; D011948:Receptors, Antigen, T-Cell / Q000502:physiology*; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000166:cytology* / Q000502:physiology; D025801:Ubiquitin / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases; D020827:rap1 GTP-Binding Proteins / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C082869:CRKL protein; D002352:Carrier Proteins; D020735:Guanine Nucleotide-Releasing Factor 2; D016169:Lymphocyte Function-Associated Antigen-1; D009687:Nuclear Proteins; D010750:Phosphoproteins; D011948:Receptors, Antigen, T-Cell; D025801:Ubiquitin; D018799:Intercellular Adhesion Molecule-1; C492211:CBLB protein, human; D050721:Proto-Oncogene Proteins c-cbl; D044767:Ubiquitin-Protein Ligases; D020827:rap1 GTP-Binding Proteins