Ankyrins are essential for synapse development in the mouse outer retina

In the outer retina, horizontal cells are important interneurons that make the first contacts to photoreceptors and begin to segregate visual information into two distinct pathways by selectively forming synapses to the distinct types of photoreceptors. Dendrites of horizontal cells synapse exclusively to cone photoreceptors whereas the axon terminal synapses to rod photoreceptors.

Failure to properly form these early connections disrupts the downstream connectivity of other post-synaptic neurons such as bipolar cells and leads to abnormal visual function. Although these early events are critical for proper synapse development, little is known about the molecular mechanisms that establish horizontal cell to photoreceptor connectivity during development. In the present study, we performed single cell RNA-sequencing and uncovered new molecules that are highly expressed in horizontal cells.