About the cover
The image shows two 3D-printed models of mouse astrocytes (orange and grey) apposed to one another as they would be found in the brain. It has long been known that astrocytes have an intimate relationship with neurons and as a result, can significantly influence the function of synapses. However, the molecular means by which an astrocyte attains its complex structure to maintain this relationship has remained obscure. In this week's issue, Cagla Eroglu and her colleagues reveal that in mice, one of the keys is the ability of astrocytes to express neuroligins, a family of cell-adhesion molecules with previously known roles at neuronal synapses. In astrocytes, neuroligins interact with neurexin proteins expressed on the neuron to regulate astrocyte morphological development and, in turn, modulate synaptic density and function. In particular, the team found that the formation and function of cortical excitatory synapses was impaired when neuroligin 2 was not expressed by the astrocyte. Given that neuroligin mutations have already been linked to neurological disorders such as schizophrenia, the researchers suggest that astrocytes may have a role in a mechanism that causes disease. Cover image: Katherine King, Duke University.