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Differences in Diurnal Rhythm of Rod Outer Segment Renewal between 129T2/SvEmsJ and C57BL/6J Mice

In all mammalian species tested to date, rod photoreceptor outer segment renewal is a circadian process synchronized by light with a burst of outer segment fragment (POS) shedding and POS phagocytosis by the adjacent retinal pigment epithelium (RPE) every morning at light onset. Recent reports show...

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Autores principales: Vargas, Jade A., Finnemann, Silvia C.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9408929/
https://www.ncbi.nlm.nih.gov/pubmed/36012733
http://dx.doi.org/10.3390/ijms23169466
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author Vargas, Jade A.
Finnemann, Silvia C.
author_facet Vargas, Jade A.
Finnemann, Silvia C.
author_sort Vargas, Jade A.
collection PubMed
description In all mammalian species tested to date, rod photoreceptor outer segment renewal is a circadian process synchronized by light with a burst of outer segment fragment (POS) shedding and POS phagocytosis by the adjacent retinal pigment epithelium (RPE) every morning at light onset. Recent reports show that RPE phagocytosis also increases shortly after dark onset in C57BL/6 (C57) mice. Genetic differences between C57 mice and 129T2/SvEmsJ (129) mice may affect regulation of outer segment renewal. Here, we used quantitative methods to directly compare outer segment renewal in C57 and 129 mouse retina. Quantification of rhodopsin-positive phagosomes in the RPE showed that in 129 mice, rod POS phagocytosis after light onset was significantly increased compared to C57 mice, but that 129 mice did not show a second peak after dark onset. Cone POS phagosome content of RPE cells did not differ by mouse strain with higher phagosome numbers after light than after dark. We further quantified externalization of the “eat me” signal phosphatidylserine by outer segment tips, which precedes POS phagocytosis. Live imaging of retina ex vivo showed that rod outer segments extended PS exposure in both strains but that frequency of outer segments with exposed PS after light onset was lower in C57 than in 129 retina. Taken together, 129 mice lacked a burst of rod outer segment renewal after dark onset. The increases in rod outer segment renewal after light and after dark onset in C57 mice were attenuated compared to the peak after light onset in 129 mice, suggesting an impairment in rhythmicity in C57 mice.
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spelling pubmed-94089292022-08-26 Differences in Diurnal Rhythm of Rod Outer Segment Renewal between 129T2/SvEmsJ and C57BL/6J Mice Vargas, Jade A. Finnemann, Silvia C. Int J Mol Sci Brief Report In all mammalian species tested to date, rod photoreceptor outer segment renewal is a circadian process synchronized by light with a burst of outer segment fragment (POS) shedding and POS phagocytosis by the adjacent retinal pigment epithelium (RPE) every morning at light onset. Recent reports show that RPE phagocytosis also increases shortly after dark onset in C57BL/6 (C57) mice. Genetic differences between C57 mice and 129T2/SvEmsJ (129) mice may affect regulation of outer segment renewal. Here, we used quantitative methods to directly compare outer segment renewal in C57 and 129 mouse retina. Quantification of rhodopsin-positive phagosomes in the RPE showed that in 129 mice, rod POS phagocytosis after light onset was significantly increased compared to C57 mice, but that 129 mice did not show a second peak after dark onset. Cone POS phagosome content of RPE cells did not differ by mouse strain with higher phagosome numbers after light than after dark. We further quantified externalization of the “eat me” signal phosphatidylserine by outer segment tips, which precedes POS phagocytosis. Live imaging of retina ex vivo showed that rod outer segments extended PS exposure in both strains but that frequency of outer segments with exposed PS after light onset was lower in C57 than in 129 retina. Taken together, 129 mice lacked a burst of rod outer segment renewal after dark onset. The increases in rod outer segment renewal after light and after dark onset in C57 mice were attenuated compared to the peak after light onset in 129 mice, suggesting an impairment in rhythmicity in C57 mice. MDPI 2022-08-22 /pmc/articles/PMC9408929/ /pubmed/36012733 http://dx.doi.org/10.3390/ijms23169466 Text en © 2022 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Brief Report
Vargas, Jade A.
Finnemann, Silvia C.
Differences in Diurnal Rhythm of Rod Outer Segment Renewal between 129T2/SvEmsJ and C57BL/6J Mice
title Differences in Diurnal Rhythm of Rod Outer Segment Renewal between 129T2/SvEmsJ and C57BL/6J Mice
title_full Differences in Diurnal Rhythm of Rod Outer Segment Renewal between 129T2/SvEmsJ and C57BL/6J Mice
title_fullStr Differences in Diurnal Rhythm of Rod Outer Segment Renewal between 129T2/SvEmsJ and C57BL/6J Mice
title_full_unstemmed Differences in Diurnal Rhythm of Rod Outer Segment Renewal between 129T2/SvEmsJ and C57BL/6J Mice
title_short Differences in Diurnal Rhythm of Rod Outer Segment Renewal between 129T2/SvEmsJ and C57BL/6J Mice
title_sort differences in diurnal rhythm of rod outer segment renewal between 129t2/svemsj and c57bl/6j mice
topic Brief Report
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9408929/
https://www.ncbi.nlm.nih.gov/pubmed/36012733
http://dx.doi.org/10.3390/ijms23169466
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