title: Tyrosine phosphorylation-mediated signal transduction in MCP-1-induced macrophage activation: role for receptor dimerization, focal adhesion protein complex and JAK/STAT pathway.
abstract: Monocyte chemoattractant protein-1 (MCP-1) plays a crucial role in the recruitment of monocytes/macrophages associated with several inflammatory diseases and malignancies. The early signal transduction mechanism of macrophage activation in response to in vitro MCP-1 treatment was investigated. The treatment of murine peritoneal macrophages with MCP-1 resulted in a significant enhancement in the tyrosine phosphorylation of cellular proteins, which peaked within 2.5-5 min of MCP-1 treatment. The MCP-1-induced tyrosine phosphorylation of cellular proteins involved the phosphorylation of non-receptor tyrosine kinases Lyn, JAK2, cytoskeletal binding protein paxillin and downstream transcription factors STAT3 and STAT5. Immunoflourescence microscopical studies on MCP-1-treated macrophages showed the cellular localization of the tyrosine-phosphorylated proteins and bundling of actin filaments at the focal adhesion points. MCP-1-induced association of focal adhesion proteins Lyn/phospho-paxillin with CCR2 was also observed by co-precipitation. Inhibitor studies with genistein on MCP-1-induced macrophage TNF and IL-1 production additionally supported the role of protein tyrosine phosphorylation in the process of macrophage activation with MCP-1. Present investigations suggest that the early events in the tyrosine kinase signal transduction pathway for macrophage activation in response to MCP-1 probably involve (1) CCR2 receptor dimerization, (2) enhanced tyrosine phosphorylation and assembly of focal adhesion complex, and (3) the activation of JAK/STAT pathway in the murine peritoneal macrophages.
mesh_terms: D000818:Animals; D018932:Chemokine CCL2 / Q000494:pharmacology*; D004268:DNA-Binding Proteins / Q000502:physiology*; D019281:Dimerization; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D053613:Janus Kinase 1; D008262:Macrophage Activation / Q000187:drug effects / Q000502:physiology*; D008297:Male; D051379:Mice; D008894:Milk Proteins; D010766:Phosphorylation / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D054390:Receptors, CCR2; D019707:Receptors, Chemokine / Q000096:biosynthesis; D050796:STAT3 Transcription Factor; D050799:STAT5 Transcription Factor; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D015534:Trans-Activators / Q000502:physiology*; D014443:Tyrosine / Q000378:metabolism* / Q000502:physiology
chemical_list: C515335:Ccr2 protein, mouse; D018932:Chemokine CCL2; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D008894:Milk Proteins; D054390:Receptors, CCR2; D019707:Receptors, Chemokine; D050796:STAT3 Transcription Factor; D050799:STAT5 Transcription Factor; C494087:Stat3 protein, mouse; D015534:Trans-Activators; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C507905:Jak1 protein, mouse; D053613:Janus Kinase 1; C496051:Ptk2 protein, mouse