SITCHY - Signal transmission at the mammalian vestibular hair cell synapses

The project aims at investigating in more detail the mechanisms and molecules responsible for afferent signal transmission by type-I and type II-HCs. Experiments will be performed by using the whole-cell patch-clamp technique in combination with innovative approaches, i.e.: 1) Patch-seq, 2) optogenetics, and 3) quantitative nano-amperometric measurement of glutamate release. Patch-seq is a modification of the whole-cell patch-clamp technique that enables mRNA sequencing of cell contents after electrophysiological recordings. Patch-seq experiments will investigate the molecular basis of functional diversity between type-I HCs and type-II HCs, in WT and CaV1.3-KO mice. Optogenetics experiments will be addressed at recording the postsynaptic (calyx) response during type-I HC depolarization as produced by blue light stimulation. For these experiments, we will use mice overexpressing channelrhodopsin 2 specifically in the sensory HCs using Otoferlin-Cre mice. We have preliminary results showing that action potential activity can be elicited in CaV1.3-KO calyces. Glutamate nano-amperometric experiments will allow to better define the amplitude and dynamics of glutamate exocytotic events in type-I and type-II HCs, in WT and CaV1.3-KO mice.