Astrocyte glypican 5 regulates synapse maturation and stabilization.

The maturation and stabilization of appropriate synaptic connections is a vital step in neural circuit development; however, the molecular signals underlying these processes are not fully understood. We show that astrocytes, through production of glypican 5 (GPC5), are required for maturation and refinement of synapses in the mouse cortex during the critical period. In the absence of astrocyte GPC5, thalamocortical synapses show structural immaturity, including smaller presynaptic terminals, decreased postsynaptic density area, and presence of more postsynaptic partners at multisynaptic connections.

The diverse actions of astrocytes during synaptic development.

In the developing brain, cortical circuits are established through a complex process of synaptogenesis, maturation, and synaptic pruning. Astrocytes carry out diverse functions during each of these stages to facilitate the formation of complex networks. Recent work has begun to demonstrate that these heterogeneous roles during excitatory synaptic development are determined by the astrocyte population, brain region, and neuron type.