Control of Hippocampal Dendritic Spine Morphology Through ephrin-A3/EphA4 Signaling

Nat Neurosci. 2003 Feb;6(2):153-60. doi: 10.1038/nn994.

Abstract

Communication between glial cells and neurons is emerging as a critical parameter of synaptic function. However, the molecular mechanisms underlying the ability of glial cells to modify synaptic structure and physiology are poorly understood. Here we describe a repulsive interaction that regulates postsynaptic morphology through the EphA4 receptor tyrosine kinase and its ligand ephrin-A3. EphA4 is enriched on dendritic spines of pyramidal neurons in the adult mouse hippocampus, and ephrin-A3 is localized on astrocytic processes that envelop spines. Activation of EphA4 by ephrin-A3 was found to induce spine retraction, whereas inhibiting ephrin/EphA4 interactions distorted spine shape and organization in hippocampal slices. Furthermore, spine irregularities in pyramidal neurons from EphA4 knockout mice and in slices transfected with kinase-inactive EphA4 indicated that ephrin/EphA4 signaling is critical for spine morphology. Thus, our data support a model in which transient interactions between the ephrin-A3 ligand and the EphA4 receptor regulate the structure of excitatory synaptic connections through neuroglial cross-talk.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Astrocytes / metabolism*
  • Astrocytes / ultrastructure
  • Cell Communication / genetics
  • Cell Size / genetics
  • Dendrites / metabolism*
  • Dendrites / ultrastructure
  • Ephrin-A3 / genetics
  • Ephrin-A3 / metabolism*
  • Ephrin-B1 / metabolism
  • Ephrin-B1 / pharmacology
  • Fluorescent Antibody Technique
  • Gene Expression Regulation / physiology
  • Hippocampus / abnormalities
  • Hippocampus / metabolism*
  • Hippocampus / ultrastructure
  • Mice
  • Mice, Knockout
  • Neuronal Plasticity / genetics
  • Phosphotransferases / deficiency
  • Phosphotransferases / genetics
  • Pyramidal Cells / metabolism
  • Pyramidal Cells / ultrastructure
  • Receptor, EphA4 / deficiency*
  • Receptor, EphA4 / genetics
  • Receptors, Eph Family / drug effects
  • Receptors, Eph Family / metabolism
  • Recombinant Fusion Proteins
  • Signal Transduction / genetics
  • Synapses / metabolism*
  • Synapses / ultrastructure
  • Synaptic Transmission / genetics*

Substances

  • Ephrin-A3
  • Ephrin-B1
  • Recombinant Fusion Proteins
  • Phosphotransferases
  • Receptor, EphA4
  • Receptors, Eph Family