title: Semaphorin 4D/plexin-B1 induces endothelial cell migration through the activation of PYK2, Src, and the phosphatidylinositol 3-kinase-Akt pathway.
abstract: Semaphorins are cell surface and secreted proteins that provide axonal guidance in neuronal tissues and regulate cell motility in many cell types. They act by binding a family of transmembrane receptors known as plexins, which belong to the c-Met family of scatter factor receptors but lack an intrinsic tyrosine kinase domain. Interestingly, we have recently shown that Plexin-B1 is highly expressed in endothelial cells and that its activation by Semaphorin 4D elicits a potent proangiogenic response (J. R. Basile, A. Barac, T. Zhu, K. L. Guan, and J. S. Gutkind, Cancer Res. 64:5212-5224, 2004). In searches for the underlying molecular mechanism, we observed that Semaphorin 4D-stimulated endothelial cell migration requires the activation of the phosphatidylinositol 3-kinase (PI3K)-Akt pathway. Surprisingly, we found that Plexin-B1 stimulates PI3K-Akt through the activation of an intracellular tyrosine kinase cascade that involves the sequential activation of PYK2 and Src. This results in the tyrosine phosphorylation of Plexin-B1, the rapid recruitment of a multimeric signaling complex that includes PYK2, Src, and PI3K to Plexin-B1 and the activation of Akt. These findings suggest that Plexin-B1 may achieve its numerous physiological functions through the direct activation of intracellular tyrosine kinase cascades.
authors.affiliation: Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA. sg39v@nih.gov
authors.forename: John R
authors.initials: JR
authors.lastname: Basile
authors.forename: Talayeh
authors.initials: T
authors.lastname: Afkhami
authors.forename: J Silvio
authors.initials: JS
authors.lastname: Gutkind
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000502:physiology*; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002465:Cell Movement; D003593:Cytoplasm / Q000378:metabolism; D004730:Endothelium, Vascular / Q000378:metabolism*; D004789:Enzyme Activation; D051418:Focal Adhesion Kinase 2; D005799:Genes, Dominant; D017228:Hepatocyte Growth Factor / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D009389:Neovascularization, Pathologic; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000502:physiology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D020917:Receptor, trkA / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D039961:Semaphorins / Q000502:physiology*; D013552:Swine; D013997:Time Factors; D014443:Tyrosine / Q000737:chemistry; D019061:src-Family Kinases / Q000378:metabolism*
chemical_list: D015703:Antigens, CD; D051418:Focal Adhesion Kinase 2; D017228:Hepatocyte Growth Factor; D009419:Nerve Tissue Proteins; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D020917:Receptor, trkA; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins; D039961:Semaphorins; D014443:Tyrosine; D019061:src-Family Kinases; C093224:CD100 antigen; C492119:PLXNB1 protein, human; C494918:AKT1 protein, human