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.

scholarly journals Loss of CEP162 function at the primary cilium delays ciliogenesis and causes retinal ciliopathy in humans

2021 ◽  
Author(s):  
Nafisa Nuzhat ◽  
Kristof Van Schil ◽  
Sandra Liakopoulos ◽  
Miriam Bauwens ◽  
Alfredo Dueñas Rey ◽  
...  
Keyword(s):  
Transition Zone ◽  
Primary Cilium ◽  
Outer Segment ◽  
Retinal Dystrophy ◽  
Mrna Levels ◽  
Loss Of Function ◽  
Photoreceptor Outer Segment ◽  
Zone Formation ◽  
Mother Centriole

Ciliopathies often comprise retinal degeneration since the photoreceptor outer segment is an adapted primary cilium. CEP162 is a distal end centriolar protein required for proper transition zone assembly during ciliogenesis and whose loss causes ciliopathy in zebrafish. CEP162 has so far not been implicated in human disease. Here, we identified a homozygous CEP162 frameshift variant, c.1935dupA (p.(E646R*5)), in retinitis pigmentosa patients from two unrelated Moroccan families, likely representing a founder allele. We found that even though mRNA levels were reduced, the truncated CEP162-E646R*5 protein was expressed and localized to the mitotic spindle during mitosis, but not at the basal body of the cilium. In CEP162 knockdown cells, expression of the truncated CEP162-E646R*5 protein is unable to restore ciliation indicating its loss of function at the cilium. In patient fibroblasts, cilia overcome the absence of CEP162 from the primary cilium by delaying ciliogenesis through the persistence of CP110 at the mother centriole. The patient fibroblasts are ultimately able to extend some abnormally long cilia that are missing key transition zone components. Defective transition zone formation likely disproportionately affects the long-living ciliary outer segment of photoreceptors resulting in retinal dystrophy. CEP162 is expressed in human retina, and we show that wild-type CEP162, but not truncated CEP162-E646R*5, specifically localizes to the distal end of centrioles of mouse photoreceptor cilia. Together, our genetic, cell-based, and in vivo modeling establish that CEP162 deficiency causes retinal ciliopathy in humans.

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 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 ABCR, the ATP-binding Cassette Transporter Responsible for Stargardt Macular Dystrophy, Is an Efficient Target of All-trans-retinal-mediated Photooxidative Damagein Vitro

2001 ◽  
Vol 276 (15) ◽  
pp. 11766-11774 ◽  
Author(s):  
Hui Sun ◽  
Jeremy Nathans
Keyword(s):  
Outer Segment ◽  
Light Exposure ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Large Body ◽  
Photoreceptor Cells ◽  
Specific Protein ◽  
Macular Dystrophy ◽  
Biologically Relevant

A large body of experimental and clinical data have documented the damaging effects of light exposure on photoreceptor cells although the identities of the biologically relevant molecular targets of photodamage are still uncertain. Several lines of evidence point to retinoids or retinoid derivatives as chromophores that can mediate light damage. We report here that ABCR, a photoreceptor-specific transporter involved in the recycling of all-trans-retinal, is unusually sensitive to photooxidation damage mediated by all-trans-retinalin vitro. Partial loss of ABCR function is responsible for Stargardt macular dystrophy, which is associated with accumulation of A2E, a diretinoid adduct within the retinal pigment epithelium. Photodamage to ABCR causes it to aggregate in SDS gels and results in the loss of retinal-stimulated ATPase activity. Peripherin/RDS and ROM-1, two structural proteins that colocalize with ABCR at the outer segment disc rim, are also significantly more susceptible to all-trans-retinal-mediated photodamage than are the major proteins from the rod outer segment. These observations imply that there may be specific protein targets of photodamage within the outer segment, and they may be especially relevant to assessing the risk of light exposure in those individuals who already have diminished ABCR activity due to mutation in one or both copies of theABCRgene.

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.

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 Localization of Usher 1 proteins to the photoreceptor calyceal processes, which are absent from mice

2012 ◽  
Vol 199 (2) ◽  
pp. 381-399 ◽  
Author(s):  
Iman Sahly ◽  
Eric Dufour ◽  
Cataldo Schietroma ◽  
Vincent Michel ◽  
Amel Bahloul ◽  
...  
Keyword(s):  
Retinal Degeneration ◽  
Outer Segment ◽  
Usher Syndrome ◽  
Retinal Dystrophy ◽  
Photoreceptor Cells ◽  
Type I ◽  
Photoreceptor Outer Segment ◽  
Membrane Interfaces ◽  
Protocadherin 15 ◽  
Cadherin 23

The mechanisms underlying retinal dystrophy in Usher syndrome type I (USH1) remain unknown because mutant mice lacking any of the USH1 proteins—myosin VIIa, harmonin, cadherin-23, protocadherin-15, sans—do not display retinal degeneration. We found here that, in macaque photoreceptor cells, all USH1 proteins colocalized at membrane interfaces (i) between the inner and outer segments in rods and (ii) between the microvillus-like calyceal processes and the outer segment basolateral region in rods and cones. This pattern, conserved in humans and frogs, was mediated by the formation of an USH1 protein network, which was associated with the calyceal processes from the early embryonic stages of outer segment growth onwards. By contrast, mouse photoreceptors lacked calyceal processes and had no USH1 proteins at the inner–outer segment interface. We suggest that USH1 proteins form an adhesion belt around the basolateral region of the photoreceptor outer segment in humans, and that defects in this structure cause the retinal degeneration in USH1 patients.

scholarly journals Macular Pigment Optical Density and Photoreceptor Outer Segment Length as Predisease Biomarkers for Age-Related Macular Degeneration

2020 ◽  
Vol 9 (5) ◽  
pp. 1347 ◽  
Author(s):  
Norihiro Nagai ◽  
Sakiko Minami ◽  
Misa Suzuki ◽  
Hajime Shinoda ◽  
Toshihide Kurihara ◽  
...  
Keyword(s):  
Macular Degeneration ◽  
Optical Density ◽  
Outer Segment ◽  
Macular Pigment ◽  
Age Related Macular Degeneration ◽  
Segment Length ◽  
Macular Pigment Optical Density ◽  
Photoreceptor Outer Segment ◽  
Age Related ◽  
Fellow Eyes

To explore predisease biomarkers, which may help screen for the risk of age-related macular degeneration (AMD) at very early stages, macular pigment optical density (MPOD) and photoreceptor outer segment (PROS) length were analyzed. Thirty late AMD fellow eyes, which are at high risk and represent the predisease condition of AMD, were evaluated and compared with 30 age-matched control eyes without retinal diseases; there was no early AMD involvement in the AMD fellow eyes. MPOD was measured using MPS2® (M.E. Technica Co. Ltd., Tokyo, Japan), and PROS length was measured based on optical coherence tomography images. MPOD levels and PROS length in the AMD fellow eyes were significantly lower and shorter, respectively, than in control eyes. MPOD and PROS length were positively correlated in control eyes (R = 0.386; p = 0.035) but not in AMD fellow eyes. Twenty (67%) AMD fellow eyes met the criteria of MPOD < 0.65 and/or PROS length < 35 μm, while only five (17%) control eyes did. After adjusting for age and sex, AMD fellow eyes more frequently satisfied the definition (p < 0.001; 95% confidence interval, 3.50–60.4; odds ratio, 14.6). The combination of MPOD and PROS length may be a useful biomarker for screening predisease AMD patients, although further studies are required in this regard.

Sign in / Sign up

Export Citation Format

Share Document