Mechanosensory hair cells in the vestibular system transduce information about head position and movement into neuronal signals.
The aim of this proposal is to elucidate the molecular mechanisms underlying synaptic transmission from vestibular hair cells to afferent fibers. The hair cells afferent synapse exhibits anatomical (synaptic bodies or ribbons) and functional (responding to graded depolarizations) specializations that distinguish them from other synapses in the nervous system. We here propose to investigate which proteins and protein-interactions important at conventional synapses are important for hair cell synaptic transmission. Furthermore, vestibular physiology lacks and understanding of the functional difference between type I and type II hair cells. Type I hair cells, found only in amniotes, are engulfed by the afferent nerve, suggesting differences in synaptic physiology. The proposed experiments are therefore further aimed at understanding the molecular and functional difference in neurotransmitter release between vestibular type I and type II hair cells. These experiments will further our molecular and biophysical understanding of the first synapse in the vestibular and auditory system. Hair cells release neurotransmitter from the basolateral end of the cell body, offering relatively easy access to synaptic areas for the introduction of toxins and peptides to acutely perturb protein function. Exocytosis will be monitored directly by measuring the increase in cell membrane area that occurs when vesicles fuse with the plasma membrane.
Specific Aim 1 tests the hypothesis that exocytosis is regulated by a specific subset of SNARE proteins. Specfic Aim 2 addresses whether vesicle recycling is limiting for exocytosis.
In Specific Aim 3 the hypothesis is tested that glutamate acts in a positive feedback loop to enhance release especially in type I hair cells. A detailed understanding of the proteins and mechanisms of release at this initial sensory synapse aid in identifying novel therapeutic approaches targeting vestibular dysfunction.
| Scharr, Alexandra L; Mooney, T Aran; Schweizer, Felix E et al. (2014) Aminoglycoside-induced damage in the statocyst of the longfin inshore squid, Doryteuthis pealeii. Biol Bull 227:51-60 |
| Quiñones, Patricia M; Luu, Cindy; Schweizer, Felix E et al. (2012) Exocytosis in the frog amphibian papilla. J Assoc Res Otolaryngol 13:39-54 |
| Schweizer, Felix E; Savin, David; Luu, Cindy et al. (2009) Distribution of high-conductance calcium-activated potassium channels in rat vestibular epithelia. J Comp Neurol 517:134-45 |
| Cruz-Martin, Alberto; Schweizer, Felix E (2008) Imbalance between excitation and inhibition among synaptic connections of CA3 pyramidal neurons in cultured hippocampal slices. Eur J Neurosci 27:1353-63 |
