The Journal of Neuroscience, May 23, 2007, 27(21):5643-5653; doi:10.1523/JNEUROSCI.0954-07.2007
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Development/Plasticity/Repair
Multiple Effects of Ephrin-A5 on Cortical Neurons Are Mediated by Src Family Kinases
Geraldine Zimmer,1
Bettina Kästner,1
Franco Weth,2 and
Jürgen Bolz1
1Institut für Allgemeine Zoologie und Tierphysiologie and 2Nachwuchsgruppe Neurogenetik, Theoretikum, Universität Jena, 07743 Jena, Germany
Correspondence should be addressed to Jürgen Bolz, Institut für Allgemeine Zoologie und Tierphysiologie, Universität Jena, Erberstrasse 1, 07743 Jena, Germany. Email: bolz{at}pan.zoo.uni-jena.de
The Eph receptor tyrosine kinases and their membrane-bound ligands, the ephrins, are involved in a variety of developmental processes such as axonal guidance, cell migration, cell adhesion, proliferation, and differentiation. In addition to repulsive effects, ephrins can also induce attractive responses. Up to now, little was known about the underlying signaling mechanisms that regulate attractive versus repulsive effects. In this study, we show that ephrin-A5 enhances the motility of cortical neurons that is dependent on the activity of Src-family kinases (SFKs). Ephrin-A5 further changes the adhesive properties of neurons by inducing the formation of cell aggregates. Using the stripe assay, we found that the motogenic effect of ephrin-A5 is the result of repulsive ephrin-A interactions. Blocking SFK function leads to a conversion of repulsion into adhesion, suggesting that SFKs can act as a biological switch for the response of EphA receptors. Finally, we discovered a ligand-induced release of membrane particles containing EphA receptors, suggesting membrane ripping as a novel mechanism to overcome the "ephrin paradox" of repulsion after high-affinity receptorligand binding.
Key words: ephrin-A5; membrane ripping; adhesion; SFKs; motility; receptor release
Received Nov. 1, 2006;
accepted March 29, 2007.
Correspondence should be addressed to Jürgen Bolz, Institut für Allgemeine Zoologie und Tierphysiologie, Universität Jena, Erberstrasse 1, 07743 Jena, Germany. Email: bolz{at}pan.zoo.uni-jena.de