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Ephrins

  1. Sreenivasulu Kilari,
  2. George Wilkinson

Published Online: 15 NOV 2011

DOI: 10.1002/9780470015902.a0000831.pub3

eLS

eLS

How to Cite

Kilari, S. and Wilkinson, G. 2011. Ephrins. eLS. .

Author Information

  1. Medical College of Wisconsin, Milwaukee, Wisconsin, USA

Publication History

  1. Published Online: 15 NOV 2011

Abstract

Ephrins are cell surface proteins which bind to the Eph family of receptor tyrosine kinases. Cell surface-attached ephrin-A ligands principally activate EphA receptors, and transmembrane ephrin-B ligands primarily activate EphB receptors. Ephs and ephrins influence many developmental processes, including compartmentalisation, cellular migration, axon guidance and angiogenesis. These developmental functions arise as Ephrin–Eph interactions shape cellular behaviours, including adhesion, migration and synaptic plasticity. Eph receptors communicate with the cytoskeleton through differential activation of small GTPases downstream of their tyrosine kinase activity. In addition to stimulating Eph receptors, ephrins signal within the cell which expresses them, a phenomenon termed ‘reverse signalling’. Ephrin-B reverse signalling relies in part on phosphorylation of the cytoplasmic tail and recruitment of cytoplasmic proteins. Both ephrins and Ephs can modify internalisation and trafficking of other cell surface effector molecules.

Key Concepts:

  • Ephrins are implicated in numerous developmental events centred around cell-contact-dependent signalling.

  • Ephrin ligands and Eph receptors participate in axon guidance, and graded expression of this system is implicated in the topographic mapping of the retinotectal projection.

  • Ephrins also critically control synaptic function.

  • In the vasculature, EphB4 and ephrin-B2 are required for angiogenesic remodelling of the primitive vascular plexus.

  • Ephrins both stimulate Eph receptor tyrosine kinases and transduce ‘reverse’ signals in the cells which express them.

  • The specific outcome of Eph–ephrin engagement depends on cellular context and on the involvement of other signalling components.

Keywords:

  • axon guidance;
  • cell migration;
  • Eph;
  • ephrin;
  • receptor tyrosine kinase;
  • signal transduction