Figure 1. Astrocytes in synaptogenesis.

A, astrocytes induce synapse formation by secreting factors such as TSP1/2, which binds to α2δ1 and neuroligin to induce structural synapse formation, and Gpc4/6, which recruits GluA1‐containing AMPA receptors to the synapse. B, there is strong evidence through co‐culture experiments that astrocyte secreted protein factors play a role in many neurodevelopmental disorders. In Down's syndrome, for example, it has been found that astrocytes secrete lower levels of TSP‐1, which may lead to changes in the structure of the synapse, though the exact mechanism of this action is not yet known.