The photoreceptor cells of the retina carry out the essential task of translating light into electrical signals, which are then transmitted to retinal bipolar neurons for further analysis before being communicated to the rest of the visual system. All visual information must pass through this obligatory pathway, which involves two synaptic relays, one from photoreceptors to bipolar cells, and another from bipolar cells to third-order neurons of the inner retina. Both of these through-conducting synapses are specialized for continuous release of chemical neurotransmitter, which is required for the proper transmission of visual information. Despite their crucial role in vision, these unique photoreceptor and bipolar-cell synapses remain poorly understood, and it is not yet known how they are able to support high rates of neurotransmitter release for prolonged periods, while other synapses in the brain fatigue rapidly during sustained stimulation. This project will use a combination of cellular electrophysiology and high-resolution fluorescence imaging to provide the first complete picture of the synaptic vesicle cycle at the special synapses of retinal bipolar neurons and photoreceptor cells. The vesicle cycle can be broken down into several components: rapid fusion of synaptic vesicles to initiate transmitter release, resupply of releasable vesicles to support continued release, movement of vesicles to and from reserve and releasable pools, compensatory endocytosis to retrieve fused vesicles, and regeneration of new releasable vesicles after endocytosis.
The specific aims of the project exploit the ability to tag synaptic vesicles and synaptic active zones with distinct fluorescent labels to observe directly the vesicle movements that underlie all these components of the vesicle cycle. Then, genetic manipulations and selective protein interference will be used to unravel the molecular machinery that gives retinal synapses the unique ability to release neurotransmitter continuously and allows them to perform their central role in transmitting visual signals. The results will provide essential new information about how the visual signals arising in the photoreceptor cells are ultimately transmitted to the rest of the brain.
|Vaithianathan, Thirumalini; Henry, Diane; Akmentin, Wendy et al. (2016) Nanoscale dynamics of synaptic vesicle trafficking and fusion at the presynaptic active zone. Elife 5:|
|Vaithianathan, Thirumalini; Henry, Diane; Akmentin, Wendy et al. (2015) Functional roles of complexin in neurotransmitter release at ribbon synapses of mouse retinal bipolar neurons. J Neurosci 35:4065-70|
|Vaithianathan, Thirumalini; Matthews, Gary (2014) Visualizing synaptic vesicle turnover and pool refilling driven by calcium nanodomains at presynaptic active zones of ribbon synapses. Proc Natl Acad Sci U S A 111:8655-60|
|Vaithianathan, Thirumalini; Akmentin, Wendy; Henry, Diane et al. (2013) The ribbon-associated protein C-terminal-binding protein 1 is not essential for the structure and function of retinal ribbon synapses. Mol Vis 19:917-26|
|Vaithianathan, Thirumalini; Zanazzi, George; Henry, Diane et al. (2013) Stabilization of spontaneous neurotransmitter release at ribbon synapses by ribbon-specific subtypes of complexin. J Neurosci 33:8216-26|
|Vega, Ana V; Avila, Guillermo; Matthews, Gary (2013) Interaction between the transcriptional corepressor Sin3B and voltage-gated sodium channels modulates functional channel expression. Sci Rep 3:2809|
|Snellman, Josefin; Mehta, Bhupesh; Babai, Norbert et al. (2011) Acute destruction of the synaptic ribbon reveals a role for the ribbon in vesicle priming. Nat Neurosci 14:1135-41|
|Hunanyan, Arsen S; Alessi, Valentina; Patel, Samik et al. (2011) Alterations of action potentials and the localization of Nav1.6 sodium channels in spared axons after hemisection injury of the spinal cord in adult rats. J Neurophysiol 105:1033-44|
|Zanazzi, George; Matthews, Gary (2010) Enrichment and differential targeting of complexins 3 and 4 in ribbon-containing sensory neurons during zebrafish development. Neural Dev 5:24|
|Matthews, Gary; Fuchs, Paul (2010) The diverse roles of ribbon synapses in sensory neurotransmission. Nat Rev Neurosci 11:812-22|
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