Article
- The EMBO Journal (1999) 18, 2165 - 2173
- doi:10.1093/emboj/18.8.2165
Surface densities of ephrin-B1 determine EphB1-coupled activation of cell attachment through 
v
3 and 51 integrins
Uyen Huynh-Do1, Elke Stein1, Andy A. Lane1, Hua Liu1, Douglas P. Cerretti2 and Thomas O. Daniel1
- Division of Nephrology, Departments of Medicine and Cell Biology, and the Vanderbilt Cancer Center, Vanderbilt University Medical Center, Nashville, TN 37232-2372 USA
- Immunex Corporation, Seattle, WA 98101, USA
Correspondence to:
Thomas O. Daniel, E-mail: tom.daniel@mcmail.vanderbilt.edu
Received 29 December 1998; Accepted 23 February 1999; Revised 23 February 1999
Abstract
Receptors of the Eph family and their ligands (ephrins) mediate developmental vascular assembly and direct axonal guidance. Migrating cell processes identify appropriate targets within migratory fields based on topographically displayed ephrin gradients. Here, EphB1 regulated cell attachment by discriminating the density at which ephrin-B1 was displayed on a reconstituted surface. EphB1–ephrin-B1 engagement did not promote cell attachment through mechanical tethering, but did activate integrin-mediated attachment. In endothelial cells, attachment to RGD peptides or fibrinogen was mediated through 
v
3 integrin. EphB1 transfection conferred ephrin-B1-responsive activation of 51 integrin-mediated cell attachment in human embryonic kidney cells. Activation-competent but signaling-defective EphB1 point mutants failed to stimulate ephrin-B1 dependent attachment. These findings lead us to propose that EphB1 functions as a 'ligand density sensor' to signal integrin-mediated cell–matrix attachment.
Keywords:
- EphB1,
- integrins,
- ligand density discrimination
