A beta 1 integrin signaling pathway involving Src-family kinases, Cbl and PI-3 kinase is required for macrophage spreading and migration.
We have used mutant macrophages which are deficient in expression of Src-family kinases to define an integrin signaling pathway that is required for macrophage adhesion and migration. Following ligation of surface integrins by fibronectin, the p120(c-cbl) (Cbl) protein rapidly becomes tyrosine phosphorylated and associated with the Src-family kinases Fgr and Lyn. In hck-/-fgr-/-lyn-/- triple mutant cells, which are defective in spreading on fibronectin-coated surfaces in vitro and show impaired migration in vivo, Cbl tyrosine phosphorylation is blocked, Cbl protein levels are low, adhesion-dependent translocation of Cbl to the membrane is impaired and Cbl-associated, membrane-localized phosphatidylinositol 3 (PI-3)-kinase activity is dramatically reduced. In contrast, adhesion-dependent activation of total cellular PI-3 kinase activity is normal in mutant cells, demonstrating that it is the membrane-associated fraction of PI-3 kinase which is most critical in regulating actin cytoskeletal rearrangements that lead to cell spreading. Treatment of wild-type cells with the Src-family-specific inhibitor PP1, Cbl antisense oligonucleotides or pharmacological inhibitors of PI-3 kinase blocks cell spreading on fibronectin surfaces. These data provide a molecular description for the role of Src-family kinases Hck, Fgr and Lyn in beta 1-integrin signal transduction in macrophages.
Department of Laboratory Medicine, University of California at San Francisco 94143-0100, USA.
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Meng
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Lowell
D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002448:Cell Adhesion / Q000235:genetics; D002464:Cell Migration Inhibition; D002465:Cell Movement / Q000235:genetics / Q000502:physiology*; D004247:DNA / Q000378:metabolism; D004789:Enzyme Activation / Q000235:genetics; D005353:Fibronectins / Q000502:physiology; D007249:Inflammation / Q000201:enzymology / Q000235:genetics / Q000473:pathology; D019012:Integrin beta1 / Q000235:genetics / Q000502:physiology*; D017737:Macrophages, Peritoneal / Q000201:enzymology / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D009154:Mutation; D016328:NF-kappa B / Q000378:metabolism; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D050722:Oncogene Protein v-cbl; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000502:physiology*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D011485:Protein Binding / Q000235:genetics; D011505:Protein-Tyrosine Kinases / Q000172:deficiency / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D051572:Proto-Oncogene Proteins c-hck; D015682:Retroviridae Proteins, Oncogenic / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*; D014443:Tyrosine / Q000378:metabolism; D019061:src-Family Kinases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
D017871:Calcium-Calmodulin-Dependent Protein Kinases; D004247:DNA; D005353:Fibronectins; D019012:Integrin beta1; D016328:NF-kappa B; D016376:Oligonucleotides, Antisense; D050722:Oncogene Protein v-cbl; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011505:Protein-Tyrosine Kinases; D011518:Proto-Oncogene Proteins; D051572:Proto-Oncogene Proteins c-hck; D015682:Retroviridae Proteins, Oncogenic; D014443:Tyrosine; D019061:src-Family Kinases; C496632:Hck protein, mouse; C060902:lyn protein-tyrosine kinase; C053102:proto-oncogene proteins c-fgr