scholarly journals Regulation of calcium homeostasis in the outer segments of rod and cone photoreceptors

2018 ◽  
Vol 67 ◽  
pp. 87-101 ◽  
Author(s):  
Frans Vinberg ◽  
Jeannie Chen ◽  
Vladimir J. Kefalov
Keyword(s):  
Calcium Homeostasis ◽  
Cone Photoreceptors ◽  
Outer Segments ◽  
Rod And Cone Photoreceptors

PRCD is Concentrated at the Base of Photoreceptor Outer Segments and is Involved in Outer Segment Disc Formation

2019 ◽  
Author(s):  
Gilad Allon ◽  
Irit Mann ◽  
Lital Remez ◽  
Elisabeth Sehn ◽  
Leah Rizel ◽  
...  
Keyword(s):  
Retinal Degeneration ◽  
Knockout Mice ◽  
Outer Segment ◽  
Mouse Retina ◽  
Cone Photoreceptors ◽  
Photoreceptor Outer Segment ◽  
Photoreceptor Outer Segments ◽  
Outer Segments ◽  
Rod And Cone Photoreceptors ◽  
Disc Formation

Abstract Mutations of the PRCD gene are associated with rod-cone degeneration in both dogs and humans. Prcd is expressed in the mouse eye as early as embryonic day 14. In the adult mouse retina PRCD is expressed in the outer segments of both rod and cone photoreceptors. Immunoelectron microscopy revealed that PRCD is located at the outer segment rim, and that it is highly concentrated at the base of the outer segment. Prcd-knockout mice present with progressive retinal degeneration, starting at 20 weeks of age and onwards. This process is reflected by a significant and progressive reduction of both scotopic and photopic electroretinographic responses, and by thinning of the retina, and specifically of the outer nuclear layer, indicating photoreceptor loss. Electron microscopy revealed severe damage to photoreceptor outer segments, which is associated with immigration of microglia cells to the Prcd-knockout retina, and accumulation of vesicles in the inter-photoreceptor space. Phagocytosis of photoreceptor outer segment discs by the retinal pigmented epithelium is severely reduced. Our data show that Prcd-knockout mice serve as a good model for retinal degeneration caused by PRCD mutations in humans. Our findings in these mice support the involvement of PRCD in outer segment disc formation of both rod and cone photoreceptors. Furthermore, they suggest a feedback mechanism which coordinates the rate of photoreceptor outer segment disc formation, shedding and phagocytosis. This study has important implications for understanding the function of PRCD in the retina, as well as for future development of treatment modalities for PRCD-deficiency in humans.

scholarly journals The retina visual cycle is driven by cis retinol oxidation in the outer segments of cones

2017 ◽  
Vol 34 ◽  
Author(s):  
SHINYA SATO ◽  
RIKARD FREDERIKSEN ◽  
M. CARTER CORNWALL ◽  
VLADIMIR J. KEFALOV
Keyword(s):  
Dark Adaptation ◽  
Enzymatic Reaction ◽  
Bright Light ◽  
Visual Cycle ◽  
Cone Photoreceptors ◽  
Molecular Identity ◽  
Outer Segments ◽  
Retinal Chromophore ◽  
Enzymatic Machinery ◽  
Rod And Cone Photoreceptors

AbstractVertebrate rod and cone photoreceptors require continuous supply of chromophore for regenerating their visual pigments after photoactivation. Cones, which mediate our daytime vision, demand a particularly rapid supply of 11-cis retinal chromophore in order to maintain their function in bright light. An important contribution to this process is thought to be the chromophore precursor 11-cis retinol, which is supplied to cones from Müller cells in the retina and subsequently oxidized to 11-cis retinal as part of the retina visual cycle. However, the molecular identity of the cis retinol oxidase in cones remains unclear. Here, as a first step in characterizing this enzymatic reaction, we sought to determine the subcellular localization of this activity in salamander red cones. We found that the onset of dark adaptation of isolated salamander red cones was substantially faster when exposing directly their outer vs. their inner segment to 9-cis retinol, an analogue of 11-cis retinol. In contrast, this difference was not observed when treating the outer vs. inner segment with 9-cis retinal, a chromophore analogue which can directly support pigment regeneration. These results suggest, surprisingly, that the cis-retinol oxidation occurs in the outer segments of cone photoreceptors. Confirming this notion, pigment regeneration with exogenously added 9-cis retinol was directly observed in the truncated outer segments of cones, but not in rods. We conclude that the enzymatic machinery required for the oxidation of recycled cis retinol as part of the retina visual cycle is present in the outer segments of cones.

Toward the generation of rod and cone photoreceptors from mouse, monkey and human embryonic stem cells

2008 ◽  
Vol 26 (2) ◽  
pp. 215-224 ◽  
Author(s):  
Fumitaka Osakada ◽  
Hanako Ikeda ◽  
Michiko Mandai ◽  
Takafumi Wataya ◽  
Kiichi Watanabe ◽  
...  
Keyword(s):  
Stem Cells ◽  
Embryonic Stem Cells ◽  
Human Embryonic Stem Cells ◽  
Embryonic Stem ◽  
Cone Photoreceptors ◽  
Rod And Cone Photoreceptors

scholarly journals Lamin B1 and lamin B2 are long-lived proteins with distinct functions in retinal development

2016 ◽  
Vol 27 (12) ◽  
pp. 1928-1937 ◽  
Author(s):  
David Razafsky ◽  
Candace Ward ◽  
Chloe Potter ◽  
Wanqiu Zhu ◽  
Yunlu Xue ◽  
...  
Keyword(s):  
Nuclear Lamina ◽  
Building Blocks ◽  
Postnatal Life ◽  
Cone Photoreceptors ◽  
Obvious Effect ◽  
Lamin B1 ◽  
Embryonic Neurogenesis ◽  
And Function ◽  
Embryonic Retina ◽  
Rod And Cone Photoreceptors

Lamin B1 and lamin B2 are essential building blocks of the nuclear lamina, a filamentous meshwork lining the nucleoplasmic side of the inner nuclear membrane. Deficiencies in lamin B1 and lamin B2 impair neurodevelopment, but distinct functions for the two proteins in the development and homeostasis of the CNS have been elusive. Here we show that embryonic depletion of lamin B1 in retinal progenitors and postmitotic neurons affects nuclear integrity, leads to the collapse of the laminB2 meshwork, impairs neuronal survival, and markedly reduces the cellularity of adult retinas. In stark contrast, a deficiency of lamin B2 in the embryonic retina has no obvious effect on lamin B1 localization or nuclear integrity in embryonic retinas, suggesting that lamin B1, but not lamin B2, is strictly required for nucleokinesis during embryonic neurogenesis. However, the absence of lamin B2 prevents proper lamination of adult retinal neurons, impairs synaptogenesis, and reduces cone photoreceptor survival. We also show that lamin B1 and lamin B2 are extremely long-lived proteins in rod and cone photoreceptors. OF interest, a complete absence of both proteins during postnatal life has little or no effect on the survival and function of cone photoreceptors.

scholarly journals A Visual Pigment Expressed in Both Rod and Cone Photoreceptors

Neuron ◽  
2001 ◽  
Vol 32 (3) ◽  
pp. 451-461 ◽  
Author(s):  
Jian-xing Ma ◽  
Sergey Znoiko ◽  
Kashelle L. Othersen ◽  
James C. Ryan ◽  
Joydip Das ◽  
...  
Keyword(s):  
Visual Pigment ◽  
Cone Photoreceptors ◽  
Rod And Cone Photoreceptors

scholarly journals The Effect of Peripherin/rds Haploinsufficiency on Rod and Cone Photoreceptors

1997 ◽  
Vol 17 (21) ◽  
pp. 8118-8128 ◽  
Author(s):  
Tong Cheng ◽  
Neal S. Peachey ◽  
Shihong Li ◽  
Yoshinobu Goto ◽  
Yun Cao ◽  
...  
Keyword(s):  
Cone Photoreceptors ◽  
Rod And Cone Photoreceptors

scholarly journals Human red and green cone opsins are O-glycosylated at an N-terminal Ser/Thr–rich domain conserved in vertebrates

2019 ◽  
Vol 294 (20) ◽  
pp. 8123-8133 ◽  
Author(s):  
David Salom ◽  
Hui Jin ◽  
Thomas A. Gerken ◽  
Clinton Yu ◽  
Lan Huang ◽  
...  
Keyword(s):  
Photoreceptor Cells ◽  
Human Retina ◽  
Cone Photoreceptor ◽  
Post Translational Modification ◽  
Terminal Sequence ◽  
Outer Segments ◽  
Rich Domain ◽  
Structural Differences ◽  
Cone Opsins ◽  
Rod And Cone Photoreceptors

There are fundamental differences in the structures of outer segments between rod and cone photoreceptor cells in the vertebrate retina. Visual pigments are the only essential membrane proteins that differ between rod and cone outer segments, making it likely that they contribute to these structural differences. Human rhodopsin is N-glycosylated on Asn2 and Asn15, whereas human (h) red and green cone opsins (hOPSR and hOPSG, respectively) are N-glycosylated at Asn34. Here, utilizing a monoclonal antibody (7G8 mAB), we demonstrate that hOPSR and hOPSG from human retina also are O-glycosylated with full occupancy. We determined that 7G8 mAB recognizes the N-terminal sequence 21DSTQSSIF28 of hOPSR and hOPSG from extracts of human retina, but only after their O-glycans have been removed with O-glycosidase treatment, thus revealing this post-translational modification of red and green cone opsins. In addition, we show that hOPSR and hOPSG from human retina are recognized by jacalin, a lectin that binds to O-glycans, preferentially to Gal–GalNAc. Next, we confirmed the presence of O-glycans on OPSR and OPSG from several vertebrate species, including mammals, birds, and amphibians. Finally, the analysis of bovine OPSR by MS identified an O-glycan on Ser22, a residue that is semi-conserved (Ser or Thr) among vertebrate OPSR and OPSG. These results suggest that O-glycosylation is a fundamental feature of red and green cone opsins, which may be relevant to their function or to cone cell development, and that differences in this post-translational modification also could contribute to the different morphologies of rod and cone photoreceptors.

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