The mammalian rod synaptic ribbon is essential for Cav channel facilitation and ultrafast synaptic vesicle fusion

Rod photoreceptors (PRs) use ribbon synapses to transmit visual information. To signal ‘no light detected’ they release glutamate continually to activate post-synaptic receptors. When light is detected glutamate release pauses. How a rod’s individual ribbon enables this process was studied here by r...

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Autores principales:	Chad Paul Grabner, Tobias Moser
Formato:	article
Lenguaje:	EN
Publicado:	eLife Sciences Publications Ltd 2021
Materias:	synaptic ribbon rod photoreceptor exocytosis synaptic transmission calcium channels active zone Medicine R Science Q Biology (General) QH301-705.5
Acceso en línea:	https://doaj.org/article/425439e748cf4eea97d9abb585b68a7b
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spelling	oai:doaj.org-article:425439e748cf4eea97d9abb585b68a7b2021-11-16T14:55:32ZThe mammalian rod synaptic ribbon is essential for Cav channel facilitation and ultrafast synaptic vesicle fusion10.7554/eLife.638442050-084Xe63844https://doaj.org/article/425439e748cf4eea97d9abb585b68a7b2021-10-01T00:00:00Zhttps://elifesciences.org/articles/63844https://doaj.org/toc/2050-084XRod photoreceptors (PRs) use ribbon synapses to transmit visual information. To signal ‘no light detected’ they release glutamate continually to activate post-synaptic receptors. When light is detected glutamate release pauses. How a rod’s individual ribbon enables this process was studied here by recording evoked changes in whole-cell membrane capacitance from wild-type and ribbonless (Ribeye-ko) mice. Wild-type rods filled with high (10 mM) or low (0.5 mM) concentrations of the Ca2+-buffer EGTA created a readily releasable pool (RRP) of 87 synaptic vesicles (SVs) that emptied as a single kinetic phase with a τ<0.4 ms. The lower concentration of EGTA accelerated Cav channel opening and facilitated release kinetics. In contrast, ribbonless rods created a much smaller RRP of 22 SVs, and they lacked Cav channel facilitation; however, Ca2+ channel-release coupling remained tight. These release deficits caused a sharp attenuation of rod-driven scotopic light responses. We conclude that the synaptic ribbon facilitates Ca2+-influx and establishes a large RRP of SVs.Chad Paul GrabnerTobias MosereLife Sciences Publications Ltdarticlesynaptic ribbonrod photoreceptorexocytosissynaptic transmissioncalcium channelsactive zoneMedicineRScienceQBiology (General)QH301-705.5ENeLife, Vol 10 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	synaptic ribbon rod photoreceptor exocytosis synaptic transmission calcium channels active zone Medicine R Science Q Biology (General) QH301-705.5
spellingShingle	synaptic ribbon rod photoreceptor exocytosis synaptic transmission calcium channels active zone Medicine R Science Q Biology (General) QH301-705.5 Chad Paul Grabner Tobias Moser The mammalian rod synaptic ribbon is essential for Cav channel facilitation and ultrafast synaptic vesicle fusion
description	Rod photoreceptors (PRs) use ribbon synapses to transmit visual information. To signal ‘no light detected’ they release glutamate continually to activate post-synaptic receptors. When light is detected glutamate release pauses. How a rod’s individual ribbon enables this process was studied here by recording evoked changes in whole-cell membrane capacitance from wild-type and ribbonless (Ribeye-ko) mice. Wild-type rods filled with high (10 mM) or low (0.5 mM) concentrations of the Ca2+-buffer EGTA created a readily releasable pool (RRP) of 87 synaptic vesicles (SVs) that emptied as a single kinetic phase with a τ<0.4 ms. The lower concentration of EGTA accelerated Cav channel opening and facilitated release kinetics. In contrast, ribbonless rods created a much smaller RRP of 22 SVs, and they lacked Cav channel facilitation; however, Ca2+ channel-release coupling remained tight. These release deficits caused a sharp attenuation of rod-driven scotopic light responses. We conclude that the synaptic ribbon facilitates Ca2+-influx and establishes a large RRP of SVs.
format	article
author	Chad Paul Grabner Tobias Moser
author_facet	Chad Paul Grabner Tobias Moser
author_sort	Chad Paul Grabner
title	The mammalian rod synaptic ribbon is essential for Cav channel facilitation and ultrafast synaptic vesicle fusion
title_short	The mammalian rod synaptic ribbon is essential for Cav channel facilitation and ultrafast synaptic vesicle fusion
title_full	The mammalian rod synaptic ribbon is essential for Cav channel facilitation and ultrafast synaptic vesicle fusion
title_fullStr	The mammalian rod synaptic ribbon is essential for Cav channel facilitation and ultrafast synaptic vesicle fusion
title_full_unstemmed	The mammalian rod synaptic ribbon is essential for Cav channel facilitation and ultrafast synaptic vesicle fusion
title_sort	mammalian rod synaptic ribbon is essential for cav channel facilitation and ultrafast synaptic vesicle fusion
publisher	eLife Sciences Publications Ltd
publishDate	2021
url	https://doaj.org/article/425439e748cf4eea97d9abb585b68a7b
work_keys_str_mv	AT chadpaulgrabner themammalianrodsynapticribbonisessentialforcavchannelfacilitationandultrafastsynapticvesiclefusion AT tobiasmoser themammalianrodsynapticribbonisessentialforcavchannelfacilitationandultrafastsynapticvesiclefusion AT chadpaulgrabner mammalianrodsynapticribbonisessentialforcavchannelfacilitationandultrafastsynapticvesiclefusion AT tobiasmoser mammalianrodsynapticribbonisessentialforcavchannelfacilitationandultrafastsynapticvesiclefusion
_version_	1718426352149856256

The mammalian rod synaptic ribbon is essential for Cav channel facilitation and ultrafast synaptic vesicle fusion

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