scholarly journals IFT20 is required for opsin trafficking and photoreceptor outer segment development

2011 ◽  
Vol 22 (7) ◽  
pp. 921-930 ◽  
Author(s):  
Brian T. Keady ◽  
Yun Zheng Le ◽  
Gregory J. Pazour
Keyword(s):  
Cell Body ◽  
Golgi Complex ◽  
Outer Segment ◽  
Intraflagellar Transport ◽  
Photoreceptor Cells ◽  
High Rate ◽  
Cell Degeneration ◽  
Photoreceptor Outer Segment ◽  
Rods And Cones ◽  
Cone Development

The light-detecting outer segments of vertebrate photoreceptors are cilia. Like other cilia, all materials needed for assembly and maintenance are synthesized in the cell body and transported into the cilium. The highly elaborated nature of the outer segment and its high rate of turnover necessitate unusually high levels of transport into the cilium. In this work, we examine the role of the IFT20 subunit of the intraflagellar transport (IFT) particle in photoreceptor cells. IFT20 was deleted in developing cones by a cone-specific Cre and in mature rods and cones by a tamoxifen-activatable Cre. Loss of IFT20 during cone development leads to opsin accumulation in the inner segment even when the connecting cilium and outer segment are still intact. With time this causes cone cell degeneration. Similarly, deletion of IFT20 in mature rods causes rapid accumulation of rhodopsin in the cell body, where it is concentrated at the Golgi complex. We further show that IFT20, acting both as part of the IFT particle and independent of the particle, binds to rhodopsin and RG-opsin. Since IFT20 dynamically moves between the Golgi complex and the connecting cilium, the current work suggests that rhodopsin and opsins are cargo for IFT transport.

scholarly journals THE RENEWAL OF PROTEIN IN RETINAL RODS AND CONES

1968 ◽  
Vol 39 (1) ◽  
pp. 169-184 ◽  
Author(s):  
Richard W. Young ◽  
Bernard Droz
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Electron Microscope ◽  
Golgi Complex ◽  
Outer Segment ◽  
Photoreceptor Cells ◽  
Rods And Cones ◽  
Retinal Rods ◽  
Utilization Of Protein ◽  
Low Levels

The renewal of protein in retinal rods and cones has been analyzed by quantitative electron microscope radioautography in adult frogs injected with a mixture of radioactive amino acids. Protein synthesis occurs predominantly in the ergastoplasm, localized in the myoid region of the photoreceptor cells. Much of the newly formed protein next flows through the Golgi complex. In rods, a large proportion of the protein then moves past the mitochondria of the ellipsoid segment, passes through the connecting cilium into the outer segment, and is there assembled into membranous discs at the base of that structure. Discs are formed at the rate of 36 per day in red rods and 25 per day in green rods at 22.5° C ambient temperature. In cones, a small proportion of the protein is similarly displaced to the outer segment. However, no new discs are formed. Instead, the protein becomes diffusely distributed throughout the cone outer segment. Low levels of radioactivity have been detected, shortly after injection, in the mitochondria, nucleus, and synaptic bodies of rods and cones. Nevertheless, in these organelles, the renewal process also appears to involve the utilization of protein formed in the ergastoplasm of the myoid.

scholarly journals Immunocytochemical localization of opsin in outer segments and Golgi zones of frog photoreceptor cells. An electron microscope analysis of cross-linked albumin-embedded retinas

1978 ◽  
Vol 77 (1) ◽  
pp. 196-210 ◽  
Author(s):  
DS Papermaster ◽  
BG Schneider ◽  
MA Zorn ◽  
JP Kraehenbuhl
Keyword(s):  
Electron Microscope ◽  
Outer Segment ◽  
Specific Binding ◽  
Photoreceptor Cells ◽  
Indirect Detection ◽  
Thin Sections ◽  
Rods And Cones ◽  
Outer Segments ◽  
Cell Structures ◽  
Cone Photopigments

Adult vertebrate retinal cells (rod and cones) continuously synthesize membrane proteins and transport them to the organelle specialized for photon capture, the outer segment. The cell structures involved in the synthesis of opsin have been identified by means of immunocytochemistry at the electron microscope level. Two indirect detection systems were used: (a) rabbit antibodies to frog opsin were localized with ferritin conjugated F(ab')2 of sheep antibodies to rabbit F(ab')2 and (b) sheep antibodies to cattle opsin were coupled to biotin and visualized by means of avidin-ferritin conjugates (AvF). The reagents were applied directly to the surface of thin sections of frog retinal tissues embedded in glutaraldehyde cross-linked bovine serum albumin (BSA). Specific binding of anti-opsin antibodies indicates that opsin is localized in the disks of rod outer segments (ROS), as expected, and in the Golgi zone of the rod cell inner segments. In addition, we observed quantitatively different labeling patterns of outer segments of rods and cones with each of the sera employed. These reactions may indicate immunological homology of rod and cone photopigments. Because these quantitiative variations of labeling density extend along the entire length of the outer segment, they also serve to identify the cell which has shed its disks into adjacent pigment ipithelial cell phagosomes.

scholarly journals A Computational Pipeline for Functional Gene Discovery

2021 ◽  
Author(s):  
Aolani Colon ◽  
Rishabh Hirday ◽  
Ami Patel ◽  
Amrita Poddar ◽  
Emma Tuberty-Vaughan ◽  
...  
Keyword(s):  
Candidate Genes ◽  
Outer Segment ◽  
Gene Discovery ◽  
Immunohistochemical Analysis ◽  
Transcriptome Profiling ◽  
Photoreceptor Cells ◽  
Functional Gene ◽  
Mouse Retina ◽  
Computational Pipeline ◽  
Photoreceptor Outer Segment

Abstract Many computational pipelines exist for the detection of differentially expressed genes. However, computational pipelines for functional gene detection are rarely exist. We developed a new computational pipeline for functional gene identification from transcriptome profiling data. Key features of the pipeline include clustering optimization by gap statistics, gene ontology analysis for each cluster, and literature analysis for functional gene discovery. By leveraging this pipeline on RNA-seq datasets of mouse retinal development studies, we identified 14 candidate genes involved in the formation of the photoreceptor outer segment. The expression of top three candidate genes (Pde8b, Laptm4b, and Nr1h4) in the outer segment of the developing mouse retina were experimentally validated by immunohistochemical analysis. This computational pipeline can accurately predict novel functional gene for a specific biological process, e.g., the outer segment development of the photoreceptor cells in the mouse retina. This pipeline is also applicable to functional gene discovery for any other biological processes and in any other organs and tissues.

scholarly journals A computational pipeline for functional gene discovery

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Aolani Colon ◽  
Rishabh Hirday ◽  
Ami Patel ◽  
Amrita Poddar ◽  
Emma Tuberty-Vaughan ◽  
...  
Keyword(s):  
Candidate Genes ◽  
Outer Segment ◽  
Gene Discovery ◽  
Immunohistochemical Analysis ◽  
Transcriptome Profiling ◽  
Photoreceptor Cells ◽  
Functional Gene ◽  
Mouse Retina ◽  
Computational Pipeline ◽  
Photoreceptor Outer Segment

AbstractMany computational pipelines exist for the detection of differentially expressed genes. However, computational pipelines for functional gene detection rarely exist. We developed a new computational pipeline for functional gene identification from transcriptome profiling data. Key features of the pipeline include batch effect correction, clustering optimization by gap statistics, gene ontology analysis of clustered genes, and literature analysis for functional gene discovery. By leveraging this pipeline on RNA-seq datasets from two mouse retinal development studies, we identified 7 candidate genes involved in the formation of the photoreceptor outer segment. The expression of top three candidate genes (Pde8b, Laptm4b, and Nr1h4) in the outer segment of the developing mouse retina were experimentally validated by immunohistochemical analysis. This computational pipeline can accurately predict novel functional gene for a specific biological process, e.g., development of the outer segment and synapses of the photoreceptor cells in the mouse retina. This pipeline can also be useful to discover functional genes for other biological processes and in other organs and tissues.

scholarly journals Kif17 phosphorylation regulates its ciliary localization and photoreceptor outer segment turnover

2018 ◽  
Author(s):  
Tylor R. Lewis ◽  
Sean R. Kundinger ◽  
Brian A. Link ◽  
Christine Insinna ◽  
Joseph C. Besharse
Keyword(s):  
Mammalian Cells ◽  
Outer Segment ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Consensus Sequence ◽  
Intraflagellar Transport ◽  
Photoreceptor Outer Segment ◽  
Transgenic Expression ◽  
Outer Segments ◽  
Ciliary Localization

AbstractBackgroundKIF17, a kinesin-2 motor that functions in intraflagellar transport, can regulate the onset of photoreceptor outer segment development. However, the function of KIF17 in a mature photoreceptor remains unclear. Additionally, the ciliary localization of KIF17 is regulated by a C-terminal consensus sequence (KRKK) that is immediately adjacent to a conserved residue (mouse S1029/zebrafish S815) previously shown to be phosphorylated by CaMKII. Yet, whether this phosphorylation can regulate the localization, and thus function, of KIF17 in ciliary photoreceptors remains unknown.ResultsUsing transgenic expression in both mammalian cells and zebrafish photoreceptors, we show that phospho-mimetic KIF17 has enhanced localization to cilia. Importantly, expression of phospho-mimetic KIF17 is associated with greatly enhanced turnover of the photoreceptor outer segment through disc shedding in a cell-autonomous manner, while genetic mutants of kif17 in zebrafish and mice have diminished disc shedding. Lastly, cone expression of constitutively active tCaMKII leads to a kif17-dependent increase in disc shedding.ConclusionsTaken together, our data support a model in which phosphorylation of KIF17 promotes its ciliary localization. In cone photoreceptor outer segments, this promotes disc shedding, a process essential for photoreceptor maintenance and homeostasis. While disc shedding has been predominantly studied in the context of the mechanisms underlying phagocytosis of outer segments by the retinal pigment epithelium, this work implicates photoreceptor-derived signaling in the underlying mechanisms of disc shedding.

scholarly journals Photoreceptor discs form through peripherin-dependent suppression of ciliary ectosome release

2017 ◽  
Vol 216 (5) ◽  
pp. 1489-1499 ◽  
Author(s):  
Raquel Y. Salinas ◽  
Jillian N. Pearring ◽  
Jin-Dong Ding ◽  
William J. Spencer ◽  
Ying Hao ◽  
...  
Keyword(s):  
Primary Cilium ◽  
Outer Segment ◽  
Genetic Material ◽  
Photoreceptor Cells ◽  
Specific Protein ◽  
Photoreceptor Outer Segment ◽  
Extracellular Signals ◽  
Membrane Surfaces ◽  
Light Capture ◽  
Innate Ability

The primary cilium is a highly conserved organelle housing specialized molecules responsible for receiving and processing extracellular signals. A recently discovered property shared across many cilia is the ability to release small vesicles called ectosomes, which are used for exchanging protein and genetic material among cells. In this study, we report a novel role for ciliary ectosomes in building the elaborate photoreceptor outer segment filled with hundreds of tightly packed “disc” membranes. We demonstrate that the photoreceptor cilium has an innate ability to release massive amounts of ectosomes. However, this process is suppressed by the disc-specific protein peripherin, which enables retained ectosomes to be morphed into discs. This new function of peripherin is performed independently from its well-established role in maintaining the high curvature of disc edges, and each function is fulfilled by a separate part of peripherin’s molecule. Our findings explain how the outer segment structure evolved from the primary cilium to provide photoreceptor cells with vast membrane surfaces for efficient light capture.

Movement of retinal along cone and rod photoreceptors

1994 ◽  
Vol 11 (2) ◽  
pp. 389-399 ◽  
Author(s):  
Jing Jin ◽  
Gregor J. Jones ◽  
M. Carter Cornwall
Keyword(s):  
Cell Body ◽  
Dark Adaptation ◽  
Visual Pigment ◽  
Outer Segment ◽  
Light Adaptation ◽  
Rod Photoreceptors ◽  
Rod Outer Segment ◽  
Rods And Cones ◽  
Outer Segments ◽  
Rod Cell

AbstractSingle isolated photoreceptors can be taken through a visual cycle of light adaptation by bleaching visual pigment, followed by dark adaptation when supplied with 11–cis retinal. Light adaptation after bleaching is manifested by faster response kinetics and a permanent reduction in sensitivity to light flashes, presumed to be due to the presence of bleached visual pigment. The recovery of flash sensitivity during dark adaptation is assumed to be due to regeneration of visual pigment to pre-bleach levels. In previous work, the outer segments of bleached, light-adapted cells were exposed to 11–cis retinal. In the present work, the cell bodies of bleached photoreceptors were exposed. We report a marked difference between rods and cones. Bleached cones recover sensitivity when their cell bodies are exposed to 11–cis retinal. Bleached rods do not. These results imply that retinal can move freely along the cone photoreceptor, but retinal either is not taken up by the rod cell body or retinal cannot move from the rod cell body to the rod outer segment. The free transfer of retinal along cone but not along rod photoreceptors could explain why, during dark adaptation in the retina, cones have access to a store of 11–cis retinal which is not available to rods. Additional experiments investigated the movement of retinal along bleached rod outer segments. The results indicate that retinal can move along the rod outer segment, but that this movement is slow, occurring at about the same rate as the regeneration of visual pigment.

scholarly journals Distribution of guanylate cyclase within photoreceptor outer segments

1996 ◽  
Vol 109 (7) ◽  
pp. 1803-1812
Author(s):  
M.A. Hallett ◽  
J.L. Delaat ◽  
K. Arikawa ◽  
C.L. Schlamp ◽  
F. Kong ◽  
...  
Keyword(s):  
Guanylate Cyclase ◽  
Actin Filaments ◽  
Outer Segment ◽  
Essential Role ◽  
Photoreceptor Cells ◽  
Rod Photoreceptor ◽  
Light Activation ◽  
Photoreceptor Outer Segment ◽  
Photoreceptor Outer Segments ◽  
Vertebrate Photoreceptor

Guanylate cyclases play an essential role in the recovery of vertebrate photoreceptor cells after light activation. Here, we have investigated how one such guanylate cyclase, RetGC-1, is distributed within light- and dark-adapted rod photoreceptor cells. Guanylate cyclase activity partitioned with the photoreceptor outer segment (OS) cytoskeleton in a light-sensitive manner. RetGC-1 was found to bind actin filaments in actin blot overlays, suggesting a mechanism for its association with the OS cytoskeleton. In retinal sections, this enzyme was immunodetected only in the OSs, where it appeared to be distributed throughout the disk membranes.

scholarly journals Accumulation of non-outer segment proteins in the outer segment underlies photoreceptor degeneration in Bardet–Biedl syndrome

2015 ◽  
Vol 112 (32) ◽  
pp. E4400-E4409 ◽  
Author(s):  
Poppy Datta ◽  
Chantal Allamargot ◽  
Joseph S. Hudson ◽  
Emily K. Andersen ◽  
Sajag Bhattarai ◽  
...  
Keyword(s):  
Protein Trafficking ◽  
Outer Segment ◽  
Primary Cilia ◽  
Leucine Zipper ◽  
Photoreceptor Cells ◽  
Photoreceptor Degeneration ◽  
Photoreceptor Outer Segment ◽  
Bardet Biedl Syndrome ◽  
Major Function ◽  
Underlying Mechanisms

Compartmentalization and polarized protein trafficking are essential for many cellular functions. The photoreceptor outer segment (OS) is a sensory compartment specialized for phototransduction, and it shares many features with primary cilia. As expected, mutations disrupting protein trafficking to cilia often disrupt protein trafficking to the OS and cause photoreceptor degeneration. Bardet–Biedl syndrome (BBS) is one of the ciliopathies associated with defective ciliary trafficking and photoreceptor degeneration. However, precise roles of BBS proteins in photoreceptor cells and the underlying mechanisms of photoreceptor degeneration in BBS are not well understood. Here, we show that accumulation of non-OS proteins in the OS underlies photoreceptor degeneration in BBS. Using a newly developed BBS mouse model [Leucine zipper transcription factor-like 1 (Lztfl1)/Bbs17 mutant], isolated OSs, and quantitative proteomics, we determined 138 proteins that are enriched more than threefold in BBS mutant OS. In contrast, only eight proteins showed a more than threefold reduction. We found striking accumulation of Stx3 and Stxbp1/Munc18-1 and loss of polarized localization of Prom1 within the Lztfl1 and Bbs1 mutant OS. Ultrastructural analysis revealed that large vesicles are formed in the BBS OS, disrupting the lamellar structure of the OS. Our findings suggest that accumulation (and consequent sequestration) of non-OS proteins in the OS is likely the primary cause of photoreceptor degeneration in BBS. Our data also suggest that a major function of BBS proteins in photoreceptors is to transport proteins from the OS to the cell body or to prevent entry of non-OS proteins into the OS.

scholarly journals PCARE and WASF3 regulate ciliary F-actin assembly that is required for the initiation of photoreceptor outer segment disk formation

2020 ◽  
Vol 117 (18) ◽  
pp. 9922-9931 ◽  
Author(s):  
Julio C. Corral-Serrano ◽  
Ideke J. C. Lamers ◽  
Jeroen van Reeuwijk ◽  
Lonneke Duijkers ◽  
Anita D. M. Hoogendoorn ◽  
...  
Keyword(s):  
Outer Segment ◽  
Actin Polymerization ◽  
Retinal Dystrophy ◽  
Photoreceptor Cells ◽  
Actin Dynamics ◽  
Mouse Retina ◽  
Specific Gene ◽  
Common Denominator ◽  
Photoreceptor Outer Segment ◽  
Disk Formation

The outer segments (OS) of rod and cone photoreceptor cells are specialized sensory cilia that contain hundreds of opsin-loaded stacked membrane disks that enable phototransduction. The biogenesis of these disks is initiated at the OS base, but the driving force has been debated. Here, we studied the function of the protein encoded by the photoreceptor-specific gene C2orf71, which is mutated in inherited retinal dystrophy (RP54). We demonstrate that C2orf71/PCARE (photoreceptor cilium actin regulator) can interact with the Arp2/3 complex activator WASF3, and efficiently recruits it to the primary cilium. Ectopic coexpression of PCARE and WASF3 in ciliated cells results in the remarkable expansion of the ciliary tip. This process was disrupted by small interfering RNA (siRNA)-based down-regulation of an actin regulator, by pharmacological inhibition of actin polymerization, and by the expression of PCARE harboring a retinal dystrophy-associated missense mutation. Using human retinal organoids and mouse retina, we observed that a similar actin dynamics-driven process is operational at the base of the photoreceptor OS where the PCARE module and actin colocalize, but which is abrogated in Pcare−/− mice. The observation that several proteins involved in retinal ciliopathies are translocated to these expansions renders it a potential common denominator in the pathomechanisms of these hereditary disorders. Together, our work suggests that PCARE is an actin-associated protein that interacts with WASF3 to regulate the actin-driven expansion of the ciliary membrane at the initiation of new outer segment disk formation.

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