Final Report Summary - EPHR SIGNALING (Proteins in cell-to-cell communication: the Eph receptors and their ephrin ligands)
Project context and objectives
Erythropoetin-producing hepatoma (Eph) receptors are cell surface protein tyrosine kinases mediating cell-cell communication. They direct key processes during development and repair of the nervous system, blood vessel formation, insulin secretion, immune system function, intestinal homeostasis and bone tissue integrity. Upon binding to their ligand, activated Eph receptors form signalling clusters.
Work performed
We set out to study the architecture of such clusters and solved crystal structures of the full ectodomain of human EphA2 (eEphA2), alone and with the receptor-binding domain of the ligand ephrinA5 (ephrinA5RBD). Unliganded eEphA2 forms linear arrays of staggered parallel receptors that involve two patches of residues conserved across A-class Ephs. eEphA2-ephrinA5RBD forms a more elaborate assembly, the interfaces of which include the same conserved regions on eEphA2, but are rearranged to accommodate ephrinA5RBD. Cell surface expression of mutant EphA2s demonstrated that these interfaces are critical for localisation at cell-cell contacts and activation-dependent degradation.
Main results
Our results suggest a 'nucleation' mechanism whereby a limited number of ligand-receptor interactions seed an arrangement of receptors which can propagate into extended signalling arrays.
This work was published in Seiradake et al. Nat. Struct. Mol. Biol. 2010 (see also http://www.nature.com/nsmb/journal/v17/n4/full/nsmb.1782.html(si apre in una nuova finestra) for more information).
Our subsequent work has extended these studies to additional ephrin-Eph complexes and is currently at the stage of functional analysis so as to validate proposed molecular mechanisms in the cellular context.
Erythropoetin-producing hepatoma (Eph) receptors are cell surface protein tyrosine kinases mediating cell-cell communication. They direct key processes during development and repair of the nervous system, blood vessel formation, insulin secretion, immune system function, intestinal homeostasis and bone tissue integrity. Upon binding to their ligand, activated Eph receptors form signalling clusters.
Work performed
We set out to study the architecture of such clusters and solved crystal structures of the full ectodomain of human EphA2 (eEphA2), alone and with the receptor-binding domain of the ligand ephrinA5 (ephrinA5RBD). Unliganded eEphA2 forms linear arrays of staggered parallel receptors that involve two patches of residues conserved across A-class Ephs. eEphA2-ephrinA5RBD forms a more elaborate assembly, the interfaces of which include the same conserved regions on eEphA2, but are rearranged to accommodate ephrinA5RBD. Cell surface expression of mutant EphA2s demonstrated that these interfaces are critical for localisation at cell-cell contacts and activation-dependent degradation.
Main results
Our results suggest a 'nucleation' mechanism whereby a limited number of ligand-receptor interactions seed an arrangement of receptors which can propagate into extended signalling arrays.
This work was published in Seiradake et al. Nat. Struct. Mol. Biol. 2010 (see also http://www.nature.com/nsmb/journal/v17/n4/full/nsmb.1782.html(si apre in una nuova finestra) for more information).
Our subsequent work has extended these studies to additional ephrin-Eph complexes and is currently at the stage of functional analysis so as to validate proposed molecular mechanisms in the cellular context.
