Beta-chemokine receptor CCR5 signals through SHP1, SHP2, and Syk.
The beta-chemokine receptor CCR5 has been shown to modulate cell migration, proliferation, and immune functions and to serve as a co-receptor for the human immunodeficiency virus. We and others have shown that CCR5 activates related adhesion focal tyrosine kinase (RAFTK)/Pyk2/CAK-beta. In this study, we further characterize the signaling molecules activated ... by CCR5 upon binding to its cognate ligand, macrophage inflammatory protein-1beta (MIP1beta). We observed enhanced tyrosine phosphorylation of the phosphatases SHP1 and SHP2 upon MIP1beta stimulation of CCR5 L1.2 transfectants and T-cells derived from peripheral blood mononuclear cells. Furthermore, we observed that SHP1 associated with RAFTK. However, using a dominant-negative phosphatase-binding mutant of RAFTK (RAFTK(m906)), we found that RAFTK does not mediate SHP1 or SHP2 phosphorylation. SHP1 and SHP2 also associated with the adaptor protein Grb2 and the Src-related kinase Syk. Pretreatment of CCR5 L1.2 transfectants or T-cells with the phosphatase inhibitor orthovanadate markedly abolished MIP1beta-induced chemotaxis. Syk was also activated upon MIP1beta stimulation of CCR5 L1.2 transfectants or T-cells and associated with RAFTK. Overexpression of a dominant-negative Src-binding mutant of RAFTK (RAFTK(m402)) significantly attenuated Syk activation, whereas overexpression of wild-type RAFTK enhanced Syk activity, indicating that RAFTK acts upstream of CCR5-mediated Syk activation. Taken together, these results suggest that MIP1beta stimulation mediated by CCR5 induces the formation of a signaling complex consisting of RAFTK, Syk, SHP1, and Grb2.
Mesh Terms:
Adaptor Proteins, Signal Transducing, Chemokine CCL4, Chemotaxis, Leukocyte, Enzyme Activation, Enzyme Inhibitors, Enzyme Precursors, Focal Adhesion Kinase 2, GRB2 Adaptor Protein, Humans, Intracellular Signaling Peptides and Proteins, Lymphoma, B-Cell, Macrophage Inflammatory Proteins, Mutagenesis, Phosphorylation, Protein Tyrosine Phosphatase, Non-Receptor Type 11, Protein Tyrosine Phosphatase, Non-Receptor Type 6, Protein Tyrosine Phosphatases, Protein-Tyrosine Kinases, Proteins, Receptors, CCR5, Recombinant Proteins, Signal Transduction, T-Lymphocytes, Transfection, Tumor Cells, Cultured, Vanadates
Adaptor Proteins, Signal Transducing, Chemokine CCL4, Chemotaxis, Leukocyte, Enzyme Activation, Enzyme Inhibitors, Enzyme Precursors, Focal Adhesion Kinase 2, GRB2 Adaptor Protein, Humans, Intracellular Signaling Peptides and Proteins, Lymphoma, B-Cell, Macrophage Inflammatory Proteins, Mutagenesis, Phosphorylation, Protein Tyrosine Phosphatase, Non-Receptor Type 11, Protein Tyrosine Phosphatase, Non-Receptor Type 6, Protein Tyrosine Phosphatases, Protein-Tyrosine Kinases, Proteins, Receptors, CCR5, Recombinant Proteins, Signal Transduction, T-Lymphocytes, Transfection, Tumor Cells, Cultured, Vanadates
J. Biol. Chem.
Date: Jun. 09, 2000
PubMed ID: 10747947
View in: Pubmed Google Scholar
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