title: EphA kinase activation regulates HGF-induced epithelial branching morphogenesis.
abstract: Eph kinases and their ephrin ligands are widely expressed in epithelial cells in vitro and in vivo. Our results show that activation of endogenous EphA kinases in Madin-Darby canine kidney (MDCK) cells negatively regulates hepatocyte growth factor/scatter factor (HGF)-induced branching morphogenesis in collagen gel. Cotreatment with HGF and ephrin-A1 reduced sprouting of cell protrusions, an early step in branching morphogenesis. Moreover, addition of ephrin-A1 after HGF stimulation resulted in collapse and retraction of preexisting cell protrusions. In a newly developed assay that simulates the localized interactions between Ephs and ephrins in vivo, immobilized ephrin-A1 suppressed HGF-induced MDCK cell scattering. Ephrin-A1 inhibited basal ERK1/2 mitogen-activated protein kinase activity; however, the ephrin-A1 effect on cell protrusion was independent of the mitogen-activated protein kinase pathway. Ephrin-A1 suppressed HGF-induced activation of Rac1 and p21-activated kinase, whereas RhoA activation was retained, leading to the preservation of stress fibers. Moreover, dominant-negative RhoA or inhibitor of Rho-associated kinase (Y27632) substantially negated the inhibitory effects of ephrin-A1. These data suggest that interfering with c-Met signaling to Rho GTPases represents a major mechanism by which EphA kinase activation inhibits HGF-induced MDCK branching morphogenesis.
mesh_terms: D000818:Animals; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects; D048429:Cell Size / Q000187:drug effects / Q000502:physiology; D003094:Collagen; D036382:Ephrin-A1 / Q000378:metabolism* / Q000494:pharmacology*; D036383:Ephrin-A2 / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects / Q000201:enzymology* / Q000648:ultrastructure*; D005782:Gels; D017228:Hepatocyte Growth Factor / Q000494:pharmacology*; D007668:Kidney / Q000166:cytology; D008024:Ligands; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D022502:Stress Fibers / Q000187:drug effects / Q000502:physiology; D020830:rac1 GTP-Binding Protein / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
chemical_list: D036382:Ephrin-A1; D036383:Ephrin-A2; D005782:Gels; D008024:Ligands; D017228:Hepatocyte Growth Factor; D003094:Collagen; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D020830:rac1 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein