Structure and evolution of neuronal wiring receptors and ligands

One of the fundamental properties of a neuronal circuit is the map of its connections. The cellular and developmental processes that allow for the growth of axons and dendrites, selection of synaptic targets, and formation of functional synapses use neuronal surface receptors and their interactions with other surface receptors, secreted ligands, and matrix molecules. Spatiotemporal regulation of the expression of these receptors and cues allows for specificity in the developmental pathways that wire stereotyped circuits. The families of molecules controlling axon guidance and synapse formation are generally conserved across animals, with some important exceptions, which have consequences for neuronal connectivity. Here, we summarize the distribution of such molecules across multiple taxa, with a focus on model organisms, evolutionary processes that led to the multitude of such molecules, and functional consequences for the diversification or loss of these receptors.

Automated summary

The map of connections is a fundamental property of a neuronal circuit. Neuronal surface receptors and their interactions with other receptors, ligands, and matrix molecules play crucial roles in the growth of axons and dendrites, selection of synaptic targets, and formation of functional synapses. The spatiotemporal regulation of these receptors and cues allows for specificity in the developmental pathways that wire stereotyped circuits. The conservation of molecular families controlling axon guidance and synapse formation is generally observed across animals, but there are exceptions that have important consequences for neuronal connectivity.