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Residual rod function in CNGB1 mutant dogs

Residual rod function in CNGB1 mutant dogs PurposeMutations in the cyclic nucleotide-gated (CNG) channel beta subunit (CNGB1) are an important cause of recessive retinitis pigmentosa. We identified a large animal model with a truncating mutation of CNGB1. This study reports the persistence of small, desensitized rod ERG responses in this model.MethodsDark-, light-adapted and chromatic ERGs were recorded in CNGB1 mutant dogs and age and breed matched controls. Comparisons were made with a dog model known to completely lack rod function; young dogs with a mutation in the rod phosphodiesterase 6 alpha subunit (PDE6A−/−). Immunohistochemistry (IHC) to label the rod CNG alpha (CNGA1) and CNGB1 subunits was performed.ResultsThe dark-adapted ERG of CNGB1 mutant dogs had a raised response threshold with lack of normal rod response and a remaining cone response. Increasing stimulus strength resulted in the appearance of a separate, slower positive waveform following the dark-adapted cone b-wave. With increasing stimulus strength this increased in amplitude and became faster to merge with the initial b-wave. Comparison of responses from PDE6A−/− (cone only dogs) with CNGB1 mutant dogs to red and blue flashes and between dark-adapted and light-adapted responses supported the hypothesis that the CNGB1 mutant dog had residual desensitized rod responses. CNGB1 mutant dogs had a small amount of CNGA1 detectable in the outer segments.ConclusionsCNGB1 mutant dogs have a residual ERG response from desensitized rods. This may be due to low levels of CNGA1 in outer segments. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Documenta Ophthalmologica Springer Journals

Residual rod function in CNGB1 mutant dogs

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References (19)

Publisher
Springer Journals
Copyright
Copyright © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2022. Springer Nature or its licensor holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
ISSN
0012-4486
eISSN
1573-2622
DOI
10.1007/s10633-022-09899-3
Publisher site
See Article on Publisher Site

Abstract

PurposeMutations in the cyclic nucleotide-gated (CNG) channel beta subunit (CNGB1) are an important cause of recessive retinitis pigmentosa. We identified a large animal model with a truncating mutation of CNGB1. This study reports the persistence of small, desensitized rod ERG responses in this model.MethodsDark-, light-adapted and chromatic ERGs were recorded in CNGB1 mutant dogs and age and breed matched controls. Comparisons were made with a dog model known to completely lack rod function; young dogs with a mutation in the rod phosphodiesterase 6 alpha subunit (PDE6A−/−). Immunohistochemistry (IHC) to label the rod CNG alpha (CNGA1) and CNGB1 subunits was performed.ResultsThe dark-adapted ERG of CNGB1 mutant dogs had a raised response threshold with lack of normal rod response and a remaining cone response. Increasing stimulus strength resulted in the appearance of a separate, slower positive waveform following the dark-adapted cone b-wave. With increasing stimulus strength this increased in amplitude and became faster to merge with the initial b-wave. Comparison of responses from PDE6A−/− (cone only dogs) with CNGB1 mutant dogs to red and blue flashes and between dark-adapted and light-adapted responses supported the hypothesis that the CNGB1 mutant dog had residual desensitized rod responses. CNGB1 mutant dogs had a small amount of CNGA1 detectable in the outer segments.ConclusionsCNGB1 mutant dogs have a residual ERG response from desensitized rods. This may be due to low levels of CNGA1 in outer segments.

Journal

Documenta Ophthalmologica – Springer Journals

Published: Dec 1, 2022

Keywords: CNGB1; Retinitis pigmentosa; Electroretinogram; Dog-model; Rod

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