Ca Sensor Synaptotagmin-1 Mediates Exocytosis in Mammalian Photoreceptors

Overview

Journal Elife

Specialty Biology

Date 2019 Jun 8

PMID 31172949

Citations 25

Authors

Justin J Grassmeyer

Asia L Cahill

Cassandra L Hays

Cody Barta

Rolen M Quadros

Channabasavaiah B Gurumurthy

Wallace B Thoreson

Affiliations

Soon will be listed here.

Abstract

To encode light-dependent changes in membrane potential, rod and cone photoreceptors utilize synaptic ribbons to sustain continuous exocytosis while making rapid, fine adjustments to release rate. Release kinetics are shaped by vesicle delivery down ribbons and by properties of exocytotic Ca sensors. We tested the role for synaptotagmin-1 (Syt1) in photoreceptor exocytosis by using novel mouse lines in which Syt1 was conditionally removed from rods or cones. Photoreceptors lacking Syt1 exhibited marked reductions in exocytosis as measured by electroretinography and single-cell recordings. Syt1 mediated all evoked release in cones, whereas rods appeared capable of some slow Syt1-independent release. Spontaneous release frequency was unchanged in cones but increased in rods lacking Syt1. Loss of Syt1 did not alter synaptic anatomy or reduce Ca currents. These results suggest that Syt1 mediates both phasic and tonic release at photoreceptor synapses, revealing unexpected flexibility in the ability of Syt1 to regulate Ca-dependent synaptic transmission.

Citing Articles

Molecular Components of Vesicle Cycling at the Rod Photoreceptor Ribbon Synapse.

Hanke-Gogokhia C, Zapadka T, Finkelstein S, Arshavsky V, Demb J Adv Exp Med Biol. 2025; 1468:325-330.

PMID: 39930217 DOI: 10.1007/978-3-031-76550-6_54.

Rod inputs arrive at horizontal cell somas in mouse retina solely via rod-cone coupling.

Thoreson W, Sladek A, Barta C, Townsend L bioRxiv. 2024; .

PMID: 39554062 PMC: 11565799. DOI: 10.1101/2024.10.30.621116.

Synaptotagmin-9 in mouse retina.

Mesnard C, Hays C, Townsend L, Barta C, Gurumurthy C, Thoreson W Vis Neurosci. 2024; 41:E003.

PMID: 39291699 PMC: 11417998. DOI: 10.1017/S0952523824000026.

Retinal inputs that drive optomotor responses of mice under mesopic conditions.

Barta C, Thoreson W IBRO Neurosci Rep. 2024; 17:138-144.

PMID: 39170059 PMC: 11338136. DOI: 10.1016/j.ibneur.2024.07.003.

The Structural and Functional Integrity of Rod Photoreceptor Ribbon Synapses Depends on Redundant Actions of Dynamins 1 and 3.

Hanke-Gogokhia C, Zapadka T, Finkelstein S, Klingeborn M, Maugel T, Singer J J Neurosci. 2024; 44(25).

PMID: 38641407 PMC: 11209669. DOI: 10.1523/JNEUROSCI.1379-23.2024.

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