A dual role for Cav1.4 Ca2+ channels in the molecular and structural organization of the rod photoreceptor synapse
J. Wesley Maddox, Kate Randall, Ravi Prakash Yadav, Brittany Williams, Jussara Hagen, Paul J Derr, Vasily Kerov, Luca Della Santina, Sheila A. Baker, Nikolai O. Artemyev, Mrinalini Hoon, Amy Lee
Abstract
Synapses are fundamental information processing units that rely on voltage-gated Ca 2+ (Ca v ) channels to trigger Ca 2+ -dependent neurotransmitter release. Ca v channels also play Ca 2+ -independent roles in other biological contexts, but whether they do so in axon terminals is unknown. Here, we addressed this unknown with respect to the requirement for Ca v 1.4 L-type channels for the formation of rod photoreceptor synapses in the retina. Using a mouse strain expressing a non-conducting mutant form of Ca v 1.4, we report that the Ca v 1.4 protein, but not its Ca 2+ conductance, is required for the molecular assembly of rod synapses; however, Ca v 1.4 Ca 2+ signals are needed for the appropriate recruitment of postsynaptic partners. Our results support a model in which presynaptic Ca v channels serve both as organizers of synaptic building blocks and as sources of Ca 2+ ions in building the first synapse of the visual pathway and perhaps more broadly in the nervous system.