A Novel Role for UNC119 as an Enhancer of Synaptic Transmission

Mammalian UNC119 is a ciliary trafficking chaperone highly expressed in the inner segment of retinal photoreceptors. Previous research has shown that UNC119 can bind to transducin, the synaptic ribbon protein RIBEYE, and the calcium-binding protein CaBP4, suggesting that UNC119 may have a role in sy...

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Bibliographic Details
Published in:International journal of molecular sciences 2023-04, Vol.24 (9), p.8106
Main Authors: Fehlhaber, Katherine E, Majumder, Anurima, Boyd, Kimberly K, Griffis, Khris G, Artemyev, Nikolai O, Fain, Gordon L, Sampath, Alapakkam P
Format: Article
Language:English
Subjects:
Animals
Bipolar cells
Calcium
Calcium channels
Calcium-binding protein
Electric potential
Glutamate
Glutamates - metabolism
Mammals - metabolism
Membrane potential
Mice
Photoelectric effect
Photoreceptors
Protein binding
Proteins
Retina
Retina - metabolism
Retinal cells
Rod outer segment membranes
Segments
Synapses
Synapses - metabolism
Synaptic transmission
Synaptic Transmission - physiology
Transducin
Transducin - metabolism
Voltage
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Summary:Mammalian UNC119 is a ciliary trafficking chaperone highly expressed in the inner segment of retinal photoreceptors. Previous research has shown that UNC119 can bind to transducin, the synaptic ribbon protein RIBEYE, and the calcium-binding protein CaBP4, suggesting that UNC119 may have a role in synaptic transmission. We made patch-clamp recordings from retinal slices in mice with the gene deleted and showed that removal of even one gene of has no effect on the rod outer segment photocurrent, but acted on bipolar cells much like background light: it depolarized membrane potential, decreased sensitivity, accelerated response decay, and decreased the Hill coefficient of the response-intensity relationship. Similar effects were seen on rod bipolar-cell current and voltage responses, and after exposure to bright light to translocate transducin into the rod inner segment. These findings indicate that deletion reduces the steady-state glutamate release rate at rod synapses, though no change in the voltage dependence of the synaptic Ca current was detected. We conclude that UNC119, either by itself or together with transducin, can facilitate the release of glutamate at rod synapses, probably by some interaction with RIBEYE or other synaptic proteins rather than by binding to CaBP4 or calcium channels.
ISSN:1422-0067
1661-6596
1422-0067
DOI:10.3390/ijms24098106