Figure 8.

The role of astrocytic ephrin-B1 in synapse maintenance. A, A balance between synapse formation and pruning underlies normal synapse maintenance in the adult hippocampus (middle). Astrocyte-specific deletion of ephrin-B1 results in increased formation of immature synapses and enhanced contextual memory (right). However, overexpression of ephrin-B1 in astrocytes triggers synapse loss and impairs memory (left). B, Astrocyte-mediated pruning of synapses is mediated through the interactions between astrocytic ephrin-B1 and synaptic EphB receptors, leading to the engulfment of synaptic sites that requires ephrin-B1 reverse signaling. Unoccupied synaptic EphB receptor may serve as an “eat me signal” to target synapses for removal.