TY - JOUR T1 - Presynaptic Ca<sub>V</sub>1.3 Channels Regulate Synaptic Ribbon Size and Are Required for Synaptic Maintenance in Sensory Hair Cells JF - The Journal of Neuroscience JO - J. Neurosci. SP - 17273 LP - 17286 DO - 10.1523/JNEUROSCI.3005-12.2012 VL - 32 IS - 48 AU - Lavinia Sheets AU - Katie S. Kindt AU - Teresa Nicolson Y1 - 2012/11/28 UR - http://www.jneurosci.org/content/32/48/17273.abstract N2 - L-type calcium channels (CaV1) are involved in diverse processes, such as neurotransmission, hormone secretion, muscle contraction, and gene expression. In this study, we uncover a role for CaV1.3a in regulating the architecture of a cellular structure, the ribbon synapse, in developing zebrafish sensory hair cells. By combining in vivo calcium imaging with confocal and super-resolution structured illumination microscopy, we found that genetic disruption or acute block of CaV1.3a channels led to enlargement of synaptic ribbons in hair cells. Conversely, activating channels reduced both synaptic-ribbon size and the number of intact synapses. Along with enlarged presynaptic ribbons in caV1.3a mutants, we observed a profound loss of juxtaposition between presynaptic and postsynaptic components. These synaptic defects are not attributable to loss of neurotransmission, because vglut3 mutants lacking neurotransmitter release develop relatively normal hair-cell synapses. Moreover, regulation of synaptic-ribbon size by Ca2+ influx may be used by other cell types, because we observed similar pharmacological effects on pinealocyte synaptic ribbons. Our results indicate that Ca2+ influx through CaV1.3 fine tunes synaptic ribbon size during hair-cell maturation and that CaV1.3 is required for synaptic maintenance. ER -