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Abstract
PURPOSE To review three inherited retinal disorders associated with diagnostic or pathognomonic electroretinogram (ERG) abnormalities: cone dystrophy with supernormal rod ERG (KCNV2), enhanced S-cone syndrome (NR2E3), and bradyopsia (RGS9/R9AP). METHODS A review of clinical details, genetic basis, and electrophysiological features in these disorders and a brief summary of the standard and nonstandard ERG techniques required to identify the disorders. RESULTS The electrophysiological features in each of these three disorders are pathognomonic such that the responsible gene can be specified. The results from nonstandard electrophysiological testing in excess of international standards are necessary to describe the pathognomonic changes in cone dystrophy with supernormal rod ERG and bradyopsia. The clinical phenotype in the disorders can be variable. Mutations in NR2E3 may additionally be associated with phenotypes other than enhanced S-cone syndrome. CONCLUSION : Characteristic ERG changes enable the diagnosis of cone dystrophy with supernormal rod ERG, enhanced S-cone syndrome, and bradyopsia and accurate genetic screening. This review highlights the need for additional nonstandard ERGs to make the diagnosis in two of these disorders.
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Li T, Lewallen M, Chen S, Yu W, Zhang N, Xie T. Multipotent stem cells isolated from the adult mouse retina are capable of producing functional photoreceptor cells. Cell Res 2013; 23:788-802. [PMID: 23567557 DOI: 10.1038/cr.2013.48] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Various stem cell types have been tested for their potential application in treating photoreceptor degenerative diseases, such as retinitis pigmentosa (RP) and age-related macular degeneration (AMD). Only embryonic stem cells (ESCs) have so far been shown to generate functional photoreceptor cells restoring light response of photoreceptor-deficient mice, but there is still some concern of tumor formation. In this study, we have successfully cultured Nestin(+)Sox2(+)Pax6(+) multipotent retinal stem cells (RSCs) from the adult mouse retina, which are capable of producing functional photoreceptor cells that restore the light response of photoreceptor-deficient rd1 mutant mice following transplantation. After they have been expanded for over 35 passages in the presence of FGF and EGF, the cultured RSCs still maintain stable proliferation and differentiation potential. Under proper differentiation conditions, they can differentiate into all the major retinal cell types found in the adult retina. More importantly, they can efficiently differentiate into photoreceptor cells under optimized differentiation conditions. Following transplantation into the subretinal space of slowly degenerating rd7 mutant eyes, RSC-derived photoreceptor cells integrate into the retina, morphologically resembling endogenous photoreceptors and forming synapases with resident retinal neurons. When transplanted into eyes of photoreceptor-deficient rd1 mutant mice, a RP model, RSC-derived photoreceptors can partially restore light response, indicating that those RSC-derived photoreceptors are functional. Finally, there is no evidence for tumor formation in the photoreceptor-transplanted eyes. Therefore, this study has demonstrated that RSCs isolated from the adult retina have the potential of producing functional photoreceptor cells that can potentially restore lost vision caused by loss of photoreceptor cells in RP and AMD.
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Affiliation(s)
- Tianqing Li
- Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, MO 64110, USA
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Qin Q, Knapinska A, Dobri N, Madoux F, Chase P, Hodder P, Petrukhin K. In pursuit of synthetic modulators for the orphan retina-specific nuclear receptor NR2E3. J Ocul Pharmacol Ther 2012; 29:298-309. [PMID: 23098562 DOI: 10.1089/jop.2012.0135] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
PURPOSE NR2E3 is an orphan nuclear receptor expressed exclusively in photoreceptor cells of the retina. NR2E3-specific modulators may prolong photoreceptor survival in patients with dry age-related macular degeneration and other forms of retinal degeneration. To definitively establish NR2E3 as a photoreceptor protection target, identification of small-molecule NR2E3 modulators and their testing in animal models of retinal degeneration are required. Development of the high-throughput screen (HTS)-compatible screen for small-molecule NR2E3 modulators is the first step toward this goal. METHODS Purification protocol for isolation of the functionally competent soluble NR2E3 protein after its expression in the insect Sf9 cells was developed. The time-resolved fluorescence energy-transfer (TR-FRET) assay assessing agonist-sensitive interaction between apo-NR2E3 and transcriptional corepressor RetCOR was used for characterization of the previously reported putative NR2E3 agonist, Compound 11a, and to conduct the HTS for novel small-molecule NR2E3 modulators (direct and inverse agonists). A counterscreen TR-FRET assay that measures the affect of test compounds on PPARγ interaction with corepressor NCOR was used for assessing the specificity of compounds identified in the HTS. RESULTS We developed the cell-free TR-FRET assay for small-molecule NR2E3 modulators, which is based on agonist-induced disruption of the interaction between GST-tagged apo-NR2E3 and MBP-tagged fragment of transcriptional corepressor RetCOR. Compound 11a, a putative NR2E3 agonist, did not affect the NR2E3-RetCOR interaction, as was established by its titration in the developed assay. The assay was miniaturized for an ultralow-volume 1,536-well format and automated into 3 simple pipetting steps. Consistent with excellent assay performance, the test runs established a Z'-score within the 0.6-0.8 range. Analysis of the mid-size National Institutes of Health collection of 315,001 structurally diverse drug-like compounds confirmed excellent assay performance, but did not reveal NR2E3-specific agonists or inverse agonists. CONCLUSIONS A robust and reliable TR-FRET assay for small-molecule NR2E3-specific modulators suitable for the analysis of million compound-strong HTS libraries was developed. A previously described putative NR2E3 agonist, Compound 11a, is unlikely to represent a direct NR2E3 agonist. Application of the developed assay for screening of a more abundant and diverse compound collection be required for identification of synthetic NR2E3 ligands.
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Affiliation(s)
- Qiong Qin
- Department of Ophthalmology, Columbia University Medical Center, New York, NY 10032, USA
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Binz N, Ali Rahman IS, Chinnery HR, McKeone R, Simpson KM, Speed TP, Lai CM, Rakoczy PE. Effect of vascular endothelial growth factor upregulation on retinal gene expression in the Kimba mouse. Clin Exp Ophthalmol 2012; 41:251-62. [PMID: 22788671 DOI: 10.1111/j.1442-9071.2012.02845.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND The Kimba mouse carries a human vascular endothelial growth factor transgene causing retinal neovascularisation similar to that seen in diabetic retinopathy. Here, we examine the relationship between differential gene expression induced by vascular endothelial growth factor overexpression and the architectural changes that occur in the retinae of these mice. METHODS Retinal gene expression changes in juvenile and adult Kimba mice were assayed by microarray and compared with age-matched wild-type littermates. Transcription of selected genes was validated by quantitative real-time polymerase chain reaction. Protein translation was determined using immunohistochemistry and enzyme-linked immunosorbent assay. RESULTS Semaphorin 3C was upregulated, and nuclear receptor subfamily 2, group 3, member 3 (Nr2e3) was downregulated in juvenile Kimba mice. Betacellulin and endothelin 2 were upregulated in adults. Semaphorin 3C colocalized with glial fibrillary acidic protein in Müller cells of Kimba retinae at greater signal intensities than in wild type. Endothelin 2 colocalised to Müller cell end feet and extended into the outer limiting membrane. Endothelin receptor type B staining was most pronounced in the inner nuclear layer, the region containing Müller cell somata. CONCLUSIONS An early spike in vascular endothelial growth factor induced significant long-term retinal neovascularisation associated with changes to the retinal ganglion, photoreceptor and Müller cells. Overexpression of vascular endothelial growth factor led to dysregulation of photoreceptor metabolism through differential expression of Nr2e3, endothelin 2, betacellulin and semaphorin 3C. Alterations in the expression of these genes may therefore play key roles in the pathological mechanisms that result from retinal neovascularisation.
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Affiliation(s)
- Nicolette Binz
- Department of Molecular Ophthalmology, Lions Eye Institute, Nedlands Centre for Ophthalmology and Visual Science, The University of Western Australia, Crawley, Western Australia
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Xiang M. Intrinsic control of mammalian retinogenesis. Cell Mol Life Sci 2012; 70:2519-32. [PMID: 23064704 DOI: 10.1007/s00018-012-1183-2] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Revised: 09/25/2012] [Accepted: 09/27/2012] [Indexed: 01/18/2023]
Abstract
The generation of appropriate and diverse neuronal and glial types and subtypes during development constitutes the critical first step toward assembling functional neural circuits. During mammalian retinogenesis, all seven neuronal and glial cell types present in the adult retina are specified from multipotent progenitors by the combined action of various intrinsic and extrinsic factors. Tremendous progress has been made over the past two decades in uncovering the complex molecular mechanisms that control retinal cell diversification. Molecular genetic studies coupled with bioinformatic approaches have identified numerous transcription factors and cofactors as major intrinsic regulators leading to the establishment of progenitor multipotency and eventual differentiation of various retinal cell types and subtypes. More recently, non-coding RNAs have emerged as another class of intrinsic factors involved in generating retinal cell diversity. These intrinsic regulatory factors are found to act in different developmental processes to establish progenitor multipotency, define progenitor competence, determine cell fates, and/or specify cell types and subtypes.
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Affiliation(s)
- Mengqing Xiang
- Center for Advanced Biotechnology and Medicine, Rutgers University, 679 Hoes Lane West, Piscataway, NJ, 08854, USA.
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Yaniv SP, Issman-Zecharya N, Oren-Suissa M, Podbilewicz B, Schuldiner O. Axon regrowth during development and regeneration following injury share molecular mechanisms. Curr Biol 2012; 22:1774-82. [PMID: 22921367 DOI: 10.1016/j.cub.2012.07.044] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Revised: 07/19/2012] [Accepted: 07/19/2012] [Indexed: 11/24/2022]
Abstract
BACKGROUND The molecular mechanisms that determine axonal growth potential are poorly understood. Intrinsic growth potential decreases with age, and thus one strategy to identify molecular pathways controlling intrinsic growth potential is by studying developing young neurons. The programmed and stereotypic remodeling of Drosophila mushroom body (MB) neurons during metamorphosis offers a unique opportunity to uncover such mechanisms. Despite emerging insights into MB γ-neuron axon pruning, nothing is known about the ensuing axon re-extension. RESULTS Using mosaic loss of function, we found that the nuclear receptor UNF (Nr2e3) is cell autonomously required for the re-extension of MB γ-axons following pruning, but not for the initial growth or guidance of any MB neuron type. We found that UNF promotes this process of developmental axon regrowth via the TOR pathway as well as a late axon guidance program via an unknown mechanism. We have thus uncovered a novel developmental program of axon regrowth that is cell autonomously regulated by the UNF nuclear receptor and the TOR pathway. CONCLUSIONS Our results suggest that UNF activates neuronal re-extension during development. Taken together, we show that axon growth during developmental remodeling is mechanistically distinct from initial axon outgrowth. Due to the involvement of the TOR pathway in axon regeneration following injury, our results also suggests that developmental regrowth shares common molecular mechanisms with regeneration following injury.
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Affiliation(s)
- Shiri P Yaniv
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
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Molday RS, Kellner U, Weber BHF. X-linked juvenile retinoschisis: clinical diagnosis, genetic analysis, and molecular mechanisms. Prog Retin Eye Res 2012; 31:195-212. [PMID: 22245536 PMCID: PMC3334421 DOI: 10.1016/j.preteyeres.2011.12.002] [Citation(s) in RCA: 208] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Revised: 12/16/2011] [Accepted: 12/19/2011] [Indexed: 01/07/2023]
Abstract
X-linked juvenile retinoschisis (XLRS, MIM 312700) is a common early onset macular degeneration in males characterized by mild to severe loss in visual acuity, splitting of retinal layers, and a reduction in the b-wave of the electroretinogram (ERG). The RS1 gene (MIM 300839) associated with the disease encodes retinoschisin, a 224 amino acid protein containing a discoidin domain as the major structural unit, an N-terminal cleavable signal sequence, and regions responsible for subunit oligomerization. Retinoschisin is secreted from retinal cells as a disulphide-linked homo-octameric complex which binds to the surface of photoreceptors and bipolar cells to help maintain the integrity of the retina. Over 190 disease-causing mutations in the RS1 gene are known with most mutations occurring as non-synonymous changes in the discoidin domain. Cell expression studies have shown that disease-associated missense mutations in the discoidin domain cause severe protein misfolding and retention in the endoplasmic reticulum, mutations in the signal sequence result in aberrant protein synthesis, and mutations in regions flanking the discoidin domain cause defective disulphide-linked subunit assembly, all of which produce a non-functional protein. Knockout mice deficient in retinoschisin have been generated and shown to display most of the characteristic features found in XLRS patients. Recombinant adeno-associated virus (rAAV) mediated delivery of the normal RS1 gene to the retina of young knockout mice result in long-term retinoschisin expression and rescue of retinal structure and function providing a 'proof of concept' that gene therapy may be an effective treatment for XLRS.
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Affiliation(s)
- Robert S Molday
- Department of Biochemistry and Molecular Biology, Centre of Macular Research, University of British Columbia, 2350 Health Sciences Mall, Vancouver, B.C. V6T 1Z3, Canada.
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Stuck MW, Conley SM, Naash MI. Defects in the outer limiting membrane are associated with rosette development in the Nrl-/- retina. PLoS One 2012; 7:e32484. [PMID: 22427845 PMCID: PMC3299663 DOI: 10.1371/journal.pone.0032484] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Accepted: 01/30/2012] [Indexed: 01/23/2023] Open
Abstract
The neural retinal leucine zipper (Nrl) knockout mouse is a widely used model to study cone photoreceptor development, physiology, and molecular biology in the absence of rods. In the Nrl−/− retina, rods are converted into functional cone-like cells. The Nrl−/− retina is characterized by large undulations of the outer nuclear layer (ONL) commonly known as rosettes. Here we explore the mechanism of rosette development in the Nrl−/− retina. We report that rosettes first appear at postnatal day (P)8, and that the structure of nascent rosettes is morphologically distinct from what is seen in the adult retina. The lumen of these nascent rosettes contains a population of aberrant cells protruding into the subretinal space that induce infolding of the ONL. Morphologically adult rosettes do not contain any cell bodies and are first detected at P15. The cells found in nascent rosettes are photoreceptors in origin but lack inner and outer segments. We show that the adherens junctions between photoreceptors and Müller glia which comprise the retinal outer limiting membrane (OLM) are not uniformly formed in the Nrl−/− retina and thus allow protrusion of a population of developing photoreceptors into the subretinal space where their maturation becomes delayed. These data suggest that the rosettes of the Nrl−/− retina arise due to defects in the OLM and delayed maturation of a subset of photoreceptors, and that rods may play an important role in the proper formation of the OLM.
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Affiliation(s)
| | | | - Muna I. Naash
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
- * E-mail:
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Clérin E, Wicker N, Mohand-Saïd S, Poch O, Sahel JA, Léveillard T. ℮-conome: an automated tissue counting platform of cone photoreceptors for rodent models of retinitis pigmentosa. BMC Ophthalmol 2011; 11:38. [PMID: 22185426 PMCID: PMC3271040 DOI: 10.1186/1471-2415-11-38] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2011] [Accepted: 12/20/2011] [Indexed: 11/24/2022] Open
Abstract
Background Retinitis pigmentosa is characterized by the sequential loss of rod and cone photoreceptors. The preservation of cones would prevent blindness due to their essential role in human vision. Rod-derived Cone Viability Factor is a thioredoxin-like protein that is secreted by rods and is involved in cone survival. To validate the activity of Rod-derived Cone Viability Factors (RdCVFs) as therapeutic agents for treating retinitis Pigmentosa, we have developed e-conome, an automated cell counting platform for retinal flat mounts of rodent models of cone degeneration. This automated quantification method allows for faster data analysis thereby accelerating translational research. Methods An inverted fluorescent microscope, motorized and coupled to a CCD camera records images of cones labeled with fluorescent peanut agglutinin lectin on flat-mounted retinas. In an average of 300 fields per retina, nine Z-planes at magnification X40 are acquired after two-stage autofocus individually for each field. The projection of the stack of 9 images is subject to a threshold, filtered to exclude aberrant images based on preset variables. The cones are identified by treating the resulting image using 13 variables empirically determined. The cone density is calculated over the 300 fields. Results The method was validated by comparison to the conventional stereological counting. The decrease in cone density in rd1 mouse was found to be equivalent to the decrease determined by stereological counting. We also studied the spatiotemporal pattern of the degeneration of cones in the rd1 mouse and show that while the reduction in cone density starts in the central part of the retina, cone degeneration progresses at the same speed over the whole retinal surface. We finally show that for mice with an inactivation of the Nucleoredoxin-like genes Nxnl1 or Nxnl2 encoding RdCVFs, the loss of cones is more pronounced in the ventral retina. Conclusion The automated platform ℮-conome used here for retinal disease is a tool that can broadly accelerate translational research for neurodegenerative diseases.
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Cheng H, Khan NW, Roger JE, Swaroop A. Excess cones in the retinal degeneration rd7 mouse, caused by the loss of function of orphan nuclear receptor Nr2e3, originate from early-born photoreceptor precursors. Hum Mol Genet 2011; 20:4102-15. [PMID: 21813656 DOI: 10.1093/hmg/ddr334] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The orphan nuclear receptor NR2E3 is a direct transcriptional target of NRL, the key basic motif leucine zipper transcription factor that dictates rod versus cone photoreceptor cell fate in the mammalian retina. The lack of NR2E3 function in humans and in retinal degeneration rd7 mutant mouse leads to increased S-cones accompanied by rod degeneration, whereas ectopic expression of Nr2e3 in the cone-only Nrl(-/-) retina generates rod-like cells that do not exhibit any visual function. Using GFP to tag the newborn rods and by 5-bromo-2'-deoxyuridine birthdating, we demonstrate that early-born post-mitotic photoreceptor precursors in the rd7 retina express cone-specific genes. Transgenic mouse studies in the rd7 background show that Nr2e3 when expressed under the control of Crx promoter can restore rod photoreceptor function and suppress cone gene expression. Furthermore, Nr2e3 expression in photoreceptor precursors committed to be rods (driven by the Nrl promoter) could completely rescue the retinal phenotype of the rd7 mice. We conclude that excess of S-cones in the rd7 retina originate from photoreceptor precursors with a 'default' fate and not from proliferation of cones and that Nr2e3 is required to suppress the expression of S-cone genes during normal rod differentiation. These studies further support the 'transcriptional dominance' model of photoreceptor cell fate determination and provide insights into the pathogenesis of retinal disease phenotypes caused by NR2E3 mutations.
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Affiliation(s)
- Hong Cheng
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI, USA
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Jelcick AS, Yuan Y, Leehy BD, Cox LC, Silveira AC, Qiu F, Schenk S, Sachs AJ, Morrison MA, Nystuen AM, DeAngelis MM, Haider NB. Genetic variations strongly influence phenotypic outcome in the mouse retina. PLoS One 2011; 6:e21858. [PMID: 21779340 PMCID: PMC3136482 DOI: 10.1371/journal.pone.0021858] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Accepted: 06/07/2011] [Indexed: 01/22/2023] Open
Abstract
Variation in genetic background can significantly influence the phenotypic outcome of both disease and non-disease associated traits. Additionally, differences in temporal and strain specific gene expression can also contribute to phenotypes in the mammalian retina. This is the first report of microarray based cross-strain analysis of gene expression in the retina investigating genetic background effects. Microarray analyses were performed on retinas from the following mouse strains: C57BL6/J, AKR/J, CAST/EiJ, and NOD.NON-H2-nb1 at embryonic day 18.5 (E18.5) and postnatal day 30.5 (P30.5). Over 3000 differentially expressed genes were identified between strains and developmental stages. Differential gene expression was confirmed by qRT-PCR, Western blot, and immunohistochemistry. Three major gene networks were identified that function to regulate retinal or photoreceptor development, visual perception, cellular transport, and signal transduction. Many of the genes in these networks are implicated in retinal diseases such as bradyopsia, night-blindness, and cone-rod dystrophy. Our analysis revealed strain specific variations in cone photoreceptor cell patterning and retinal function. This study highlights the substantial impact of genetic background on both development and function of the retina and the level of gene expression differences tolerated for normal retinal function. These strain specific genetic variations may also be present in other tissues. In addition, this study will provide valuable insight for the development of more accurate models for human retinal diseases.
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Affiliation(s)
- Austin S. Jelcick
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Yang Yuan
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Barrett D. Leehy
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Lakeisha C. Cox
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Alexandra C. Silveira
- Ocular Molecular Genetics Institute, Department of Ophthalmology, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States of America
| | - Fang Qiu
- Division of Biostatistics, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Sarah Schenk
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Andrew J. Sachs
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Margaux A. Morrison
- Ocular Molecular Genetics Institute, Department of Ophthalmology, Harvard Medical School, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States of America
| | - Arne M. Nystuen
- Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Margaret M. DeAngelis
- Moran Eye Center, University of Utah, Salt Lake City, Utah, United States of America
| | - Neena B. Haider
- Department of Ophthalmology, Harvard Medical School, Schepens Eye Research Institute, Boston, Massachusetts, United States of America
- * E-mail:
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Abstract
Mammalian retinas display an astonishing diversity in the spatial arrangement of their spectral cone photoreceptors, probably in adaptation to different visual environments. Opsin expression patterns like the dorsoventral gradients of short-wave-sensitive (S) and middle- to long-wave-sensitive (M) cone opsin found in many species are established early in development and thought to be stable thereafter throughout life. In mouse early development, thyroid hormone (TH), through its receptor TRβ2, is an important regulator of cone spectral identity. However, the role of TH in the maintenance of the mature cone photoreceptor pattern is unclear. We here show that TH also controls adult cone opsin expression. Methimazole-induced suppression of serum TH in adult mice and rats yielded no changes in cone numbers but reversibly altered cone patterns by activating the expression of S-cone opsin and repressing the expression of M-cone opsin. Furthermore, treatment of athyroid Pax8(-/-) mice with TH restored a wild-type pattern of cone opsin expression that reverted back to the mutant S-opsin-dominated pattern after termination of treatment. No evidence for cone death or the generation of new cones from retinal progenitors was found in retinas that shifted opsin expression patterns. Together, this suggests that opsin expression in terminally differentiated mammalian cones remains subject to control by TH, a finding that is in contradiction to previous work and challenges the current view that opsin identity in mature mammalian cones is fixed by permanent gene silencing.
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Analysis of transcriptional regulatory pathways of photoreceptor genes by expression profiling of the Otx2-deficient retina. PLoS One 2011; 6:e19685. [PMID: 21602925 PMCID: PMC3094341 DOI: 10.1371/journal.pone.0019685] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Accepted: 04/04/2011] [Indexed: 11/19/2022] Open
Abstract
In the vertebrate retina, the Otx2 transcription factor plays a crucial role in the cell fate determination of both rod and cone photoreceptors. We previously reported that Otx2 conditional knockout (CKO) mice exhibited a total absence of rods and cones in the retina due to their cell fate conversion to amacrine-like cells. In order to investigate the entire transcriptome of the Otx2 CKO retina, we compared expression profile of Otx2 CKO and wild-type retinas at P1 and P12 using microarray. We observed that expression of 101- and 1049-probe sets significantly decreased in the Otx2 CKO retina at P1 and P12, respectively, whereas, expression of 3- and 4149-probe sets increased at P1 and P12, respectively. We found that expression of genes encoding transcription factors involved in photoreceptor development, including Crx, Nrl, Nr2e3, Esrrb, and NeuroD, was markedly down-regulated in the Otx2 CKO at both P1 and P12. Furthermore, we identified three human retinal disease loci mapped in close proximity to certain down-regulated genes in the Otx2 CKO retina including Ccdc126, Tnfsf13 and Pitpnm1, suggesting that these genes are possibly responsible for these diseases. These transcriptome data sets of the Otx2 CKO retina provide a resource on developing rods and cones to further understand the molecular mechanisms underlying photoreceptor development, function and disease.
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Nuclear receptor Rev-erb alpha (Nr1d1) functions in concert with Nr2e3 to regulate transcriptional networks in the retina. PLoS One 2011; 6:e17494. [PMID: 21408158 PMCID: PMC3050883 DOI: 10.1371/journal.pone.0017494] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Accepted: 02/07/2011] [Indexed: 12/23/2022] Open
Abstract
The majority of diseases in the retina are caused by genetic mutations affecting the development and function of photoreceptor cells. The transcriptional networks directing these processes are regulated by genes such as nuclear hormone receptors. The nuclear hormone receptor gene Rev-erb alpha/Nr1d1 has been widely studied for its role in the circadian cycle and cell metabolism, however its role in the retina is unknown. In order to understand the role of Rev-erb alpha/Nr1d1 in the retina, we evaluated the effects of loss of Nr1d1 to the developing retina and its co-regulation with the photoreceptor-specific nuclear receptor gene Nr2e3 in the developing and mature retina. Knock-down of Nr1d1 expression in the developing retina results in pan-retinal spotting and reduced retinal function by electroretinogram. Our studies show that NR1D1 protein is co-expressed with NR2E3 in the outer neuroblastic layer of the developing mouse retina. In the adult retina, NR1D1 is expressed in the ganglion cell layer and is co-expressed with NR2E3 in the outer nuclear layer, within rods and cones. Several genes co-targeted by NR2E3 and NR1D1 were identified that include: Nr2c1, Recoverin, Rgr, Rarres2, Pde8a, and Nupr1. We examined the cyclic expression of Nr1d1 and Nr2e3 over a twenty-four hour period and observed that both nuclear receptors cycle in a similar manner. Taken together, these studies reveal a novel role for Nr1d1, in conjunction with its cofactor Nr2e3, in regulating transcriptional networks critical for photoreceptor development and function.
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A novel mutation (Cys83Tyr) in the second zinc finger of NR2E3 in enhanced S-cone syndrome. Graefes Arch Clin Exp Ophthalmol 2010; 249:201-8. [PMID: 20725840 DOI: 10.1007/s00417-010-1482-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Revised: 07/25/2010] [Accepted: 07/26/2010] [Indexed: 10/19/2022] Open
Abstract
BACKGROUND Enhanced S-cone syndrome (ESCS) is an autosomal recessive retinal disorder characterized by an increased number of S-cones over L/M cones and rods. Mutations in the NR2E3 gene, encoding a photoreceptor-specific nuclear receptor, are identified in patients with ESCS. The purpose of this study is to report the ophthalmic features of a 25-year-old Portuguese male with a typical ESCS phenotype and a novel homozygous NR2E3 mutation. METHODS The patient underwent a detailed ophthalmic examination including fundus photography, fluorescein angiography (FAF), fundus autofluorescence imaging (FAI), and spectral domain optical coherence tomography (SD-OCT). Full-field electroretinography (ERG), S-cone ERG, and multifocal ERG were performed. Mutation screening of the NR2E3 gene was performed with polymerase chain reaction amplification and direct sequencing. RESULTS The patient had poor visual acuity but good color vision. Funduscopy showed degenerative changes from the vascular arcades to the midperipheral retina. The SD-OCT revealed macular schisis and cystoid changes that had no fluorescein leakage. The posterior pole showed diffusely increased autofluorescence compared with eccentric areas in both eyes. International-standard full-field ERG showed the typical pathognomonic changes associated with ESCS and the short-wavelength flash ERG was simplified, delayed, and similar to the standard photopic flash ERG. Multifocal ERG showed widespread delay and reduction. Genetic analysis revealed a novel homozygous mutation (p.C83Y), which resides in the second zinc finger of the DNA-binding domain. CONCLUSIONS This homozygous mutation is likely to affect binding to target DNA sites, resulting in a non-functional behavior of NR2E3 protein. It is associated with a typical form of ESCS with a nondetectable rod response and reduced/delayed mfERG responses at all eccentricities.
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Reese BE. Development of the retina and optic pathway. Vision Res 2010; 51:613-32. [PMID: 20647017 DOI: 10.1016/j.visres.2010.07.010] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2010] [Revised: 07/04/2010] [Accepted: 07/13/2010] [Indexed: 12/30/2022]
Abstract
Our understanding of the development of the retina and visual pathways has seen enormous advances during the past 25years. New imaging technologies, coupled with advances in molecular biology, have permitted a fuller appreciation of the histotypical events associated with proliferation, fate determination, migration, differentiation, pathway navigation, target innervation, synaptogenesis and cell death, and in many instances, in understanding the genetic, molecular, cellular and activity-dependent mechanisms underlying those developmental changes. The present review considers those advances associated with the lineal relationships between retinal nerve cells, the production of retinal nerve cell diversity, the migration, patterning and differentiation of different types of retinal nerve cells, the determinants of the decussation pattern at the optic chiasm, the formation of the retinotopic map, and the establishment of ocular domains within the thalamus.
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Affiliation(s)
- Benjamin E Reese
- Neuroscience Research Institute and Department of Psychology, University of California at Santa Barbara, Santa Barbara, CA 93106-5060, USA.
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Quantitative fine-tuning of photoreceptor cis-regulatory elements through affinity modulation of transcription factor binding sites. Gene Ther 2010; 17:1390-9. [PMID: 20463752 DOI: 10.1038/gt.2010.77] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Given the remarkable recent progress in gene therapy-based treatments for retinal disease, there is an urgent need for the development of new approaches to quantitative design and analysis of photoreceptor-specific promoters. In this study, we determined the relative binding affinity of all single-nucleotide variants of the consensus binding site of the mammalian photoreceptor transcription factor, Crx. We then showed that it is possible to use these data to accurately predict the relative binding affinity of Crx for all possible 8 bp sequences. By rationally adjusting the binding affinity of three Crx sites, we were able to fine-tune the expression of the rod-specific Rhodopsin promoter over a 225-fold range in living retinas. In addition, we showed that it is possible to fine-tune the activity of the rod-specific Gnat1 promoter over ∼275-fold range by modulating the affinity of a single Crx-binding site. We found that the action of individual binding sites depends on the precise promoter context of the site and that increasing binding affinity does not always equate with increased promoter output. Despite these caveats, this tuning approach permits quantitative engineering of photoreceptor-specific cis-regulatory elements, which can be used as drivers in gene therapy vectors for the treatment of blindness.
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Ramkumar HL, Zhang J, Chan CC. Retinal ultrastructure of murine models of dry age-related macular degeneration (AMD). Prog Retin Eye Res 2010; 29:169-90. [PMID: 20206286 DOI: 10.1016/j.preteyeres.2010.02.002] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Age-related macular degeneration (AMD) is the most prevalent form of irreversible blindness worldwide in the elderly population. The pathology of dry AMD consists of macular degeneration of photoreceptors and the RPE, lipofuscin (A2E) accumulation, and drusen formation. Mice have been widely used for generating models that simulate human AMD features for investigating the pathogenesis, treatment and prevention of the disease. Although the mouse has no macula, focal atrophy of photoreceptors and RPE, lipofuscin accumulation, and increased A2E can develop in aged mouse eyes. However, drusen are rarely seen in mice because of their simpler Bruch's membrane and different process of lipofuscin extrusion compared with humans. Thus, analyzing basal deposits at the ultrastructural level and understanding the ultrastructural pathologic differences between various mouse AMD models are critical to comprehending the significance of research findings and response to possible therapeutic options for dry AMD. Based on the multifactorial pathogenesis of AMD, murine dry AMD models can be classified into three groups. First, genetically engineered mice that target genes related to juvenile macular dystrophies are the most common models, and they include abcr(-/-) (Stargardt disease), transgenic ELOVL4 (Stargardt-3 dominant inheritary disease), Efemp1(R345W/R345W) (Doyne honeycomb retinal dystrophy), and Timp3(S156C/S156C) (Sorsby fundus dystrophy) mice. Other murine models target genes relevant to AMD, including inflammatory genes such as Cfh(-/-), Ccl2(-/-), Ccr2(-/-), Cx3cr1(-/-), and Ccl2(-/-)/cx3cr1(-/-), oxidative stress associated genes such as Sod1(-/-) and Sod2 knockdown, metabolic pathway genes such as neprilysin(-/-) (amyloid beta), transgenic mcd/mcd (cathepsin D), Cp(-/-)/Heph(-/Y) (ferroxidase ceruloplasmin/hepaestin, iron metabolism), and transgenic ApoE4 on high fat and high cholesterol diet (lipid metabolism). Second, mice have also been immunologically manipulated by immunization with carboxyethylpyrrole (CEP), an oxidative fragment of DHA found in drusen, and found to present with dry AMD features. Third, natural mouse strains such as arrd2/arrd2 (Mdm gene mutation) and the senescence accelerated mice (SAM) spontaneously develop features of dry AMD like photoreceptor atrophy and thickening of Bruch's membrane. All the aforementioned models develop retinal lesions with various features that simulate dry AMD lesions: focal photoreceptor degeneration, abnormal RPE with increased lipofuscin, basal infolding, decreased melanosomes and degeneration. However, Bruch's membrane changes are less common. Most mice develop retinal lesions at an older age (6-24 months, depending on the models), while the Ccl2(-/-)/cx3cr1(-/-) mice develop lesions by 4-6 weeks. Although murine models present various degrees of retinal and/or RPE degeneration, classical drusen is extremely rare. Using electron microscopy, small drusenoid deposits are found between RPE and Bruch's membrane in a few models including Efemp1(R345W/R345W), Ccl2(-/-)/cx3cr1(-/-), neprilysin(-/-), transgenic mcd/mcd, and ApoE4 transgenic mice on a high fat diet. High A2E levels are measured in the retinas of abcr(-/-), transgenic ELOVL4, and Ccl2(-/-)/cx3cr1(-/-) mice. In summary, murine models provide useful tools for studying AMD pathogenesis and evaluating novel therapies for this disease. This review compares the major dry AMD murine models and discusses retinal pathology at the ultrastructural level.
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Affiliation(s)
- Hema L Ramkumar
- Immunopathology Section, Laboratory of Immunology, National Eye Institute, National Institutes of Health, Bethesda, MD 20892-1857, USA
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Schorderet DF, Escher P. NR2E3 mutations in enhanced S-cone sensitivity syndrome (ESCS), Goldmann-Favre syndrome (GFS), clumped pigmentary retinal degeneration (CPRD), and retinitis pigmentosa (RP). Hum Mutat 2010; 30:1475-85. [PMID: 19718767 DOI: 10.1002/humu.21096] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
NR2E3, also called photoreceptor-specific nuclear receptor (PNR), is a transcription factor of the nuclear hormone receptor superfamily whose expression is uniquely restricted to photoreceptors. There, its physiological activity is essential for proper rod and cone photoreceptor development and maintenance. Thirty-two different mutations in NR2E3 have been identified in either homozygous or compound heterozygous state in the recessively inherited enhanced S-cone sensitivity syndrome (ESCS), Goldmann-Favre syndrome (GFS), and clumped pigmentary retinal degeneration (CPRD). The clinical phenotype common to all these patients is night blindness, rudimental or absent rod function, and hyperfunction of the "blue" S-cones. A single p.G56R mutation is inherited in a dominant manner and causes retinitis pigmentosa (RP). We have established a new locus-specific database for NR2E3 (www.LOVD.nl/eye), containing all reported mutations, polymorphisms, and unclassified sequence variants, including novel ones. A high proportion of mutations are located in the evolutionarily-conserved DNA-binding domains (DBDs) and ligand-binding domains (LBDs) of NR2E3. Based on homology modeling of these NR2E3 domains, we propose a structural localization of mutated residues. The high variability of clinical phenotypes observed in patients affected by NR2E3-linked retinal degenerations may be caused by different disease mechanisms, including absence of DNA-binding, altered interactions with transcriptional coregulators, and differential activity of modifier genes.
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Macular function assessed by microperimetry in patients with enhanced S-cone syndrome. Ophthalmology 2010; 117:1199-1206.e1. [PMID: 20171741 DOI: 10.1016/j.ophtha.2009.10.046] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Revised: 10/30/2009] [Accepted: 10/30/2009] [Indexed: 11/21/2022] Open
Abstract
PURPOSE Enhanced S-cone syndrome (ESCS), also known as Goldmann-Favre syndrome, is a progressive retinal degeneration that frequently presents with night blindness and nummular pigment clumping around the vascular arcades and is caused by recessive mutations in the photoreceptor-specific NR2E3 transcription factor. A unique feature of this disease is the development of retinoschisis of the macula. This study used fine anatomic and functional assessments within this region to determine whether the loss of retinal function was due to progressive schisis or a primary photoreceptor loss, similar to other rod-cone dystrophies. DESIGN Cross-sectional, prospective study. PARTICIPANTS Nine probands (n=18 eyes) and 3 controls (n=6 eyes) were studied at Moorfields Eye Hospital in London, United Kingdom. METHODS Histories were obtained and visual acuity was measured using Early Treatment Diabetic Retinopathy Study protocol. Autofluorescence (AF), fundus photography, and spectral domain optical coherence tomography (OCT) imaging were co-registered to detailed microperimetry (Nidek MP1; NAVIS software version 1.7.2; Nidek Technologies, Padova, Italy) data for statistical analysis. MAIN OUTCOME MEASURES Retinal sensitivity (decibels) in a customized test grid of the macula; retinal structure assessed with OCT and AF. RESULTS Patients were divided into 3 cohorts roughly based on life span and documentation of schisis: (1) no schisis, childhood; (2) macular schisis, young adults; (3) resolved schisis, older adults. Retinal sensitivity was significantly attenuated in those with schisis and did not recover in those whose schisis had resolved despite retinal thickness comparable to that of controls. All probands exhibited loss of AF peripherally (and corresponding loss of retinal sensitivity), but there was relative preservation of AF within the macula. CONCLUSIONS Development of macular retinoschisis in ESCS is an important feature of the disease and contributes to attenuated retinal sensitivity that persists after resolution of retinoschisis. The central macula appears to be compromised more by foveoschisis than photoreceptor loss. In contrast, the peripheral retina (ordinarily a rod-rich region) is affected early in the disease process and degenerates rapidly because of photoreceptor loss. Thus, 2 distinct mechanisms of retinal degeneration may exist in ESCS, corresponding to regions of the retina that may experience either normal or abnormal photoreceptor development.
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Bonilha VL, Fishman GA, Rayborn ME, Hollyfield JG. Retinal pathology of a patient with Goldmann-Favre syndrome. Ophthalmic Genet 2009; 30:172-80. [PMID: 19852574 PMCID: PMC3655805 DOI: 10.3109/13816810903176765] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
PURPOSE To define the retinal pathology in an 88-year-old male affected with Goldmann-Favre syndrome with a 2 bp 5' A>C splice site mutation in the NR2E3 gene. METHODS Retinal tissue from the macula and periphery was processed for immunohistochemistry. Perimacular retina was processed for transmission electron microscopy. Cryosections were studied by indirect immunofluorescence, using well-characterized antibodies to rhodopsin, cone cytoplasm, and cone opsins. The affected donor eye was compared to a postmortem matched normal eye. RESULTS The retina was highly disorganized without laminar organization. The RPE was discontinuous in some perimacular regions. Large (>1 mm) spherical electrondense melanosomes were observed in the RPE and choroid by TEM. Rods were virtually absent in the affected retina. Cones were present in the macula, but were mostly absent from the retinal periphery. In addition, cone rosettes were observed in the perimacular area. Both red/green and blue cone opsins were distributed along the entire cellular expanse of the cone photoreceptors in the affected eye, but were restricted to the cone outer segments in the control retina. CONCLUSIONS The histological data obtained from the retina of an elderly male patient with Goldmann-Favre syndrome showed an absence of rods and abnormal distribution of red/green and blue cone opsins.
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Affiliation(s)
- Vera L Bonilha
- The Cole Eye Institute, The Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA.
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Shu X, Zeng Z, Gautier P, Lennon A, Gakovic M, Patton EE, Wright AF. Zebrafish Rpgr is required for normal retinal development and plays a role in dynein-based retrograde transport processes. Hum Mol Genet 2009; 19:657-70. [DOI: 10.1093/hmg/ddp533] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
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Dutt K, Cao Y. Engineering retina from human retinal progenitors (cell lines). Tissue Eng Part A 2009; 15:1401-13. [PMID: 19113950 DOI: 10.1089/ten.tea.2007.0358] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Retinal degeneration resulting in the loss of photoreceptors is the leading cause of blindness. Several therapeutic protocols are under consideration for treatment of this disease. Tissue replacement is one such strategy currently being explored. However, availability of tissues for transplant poses a major obstacle. Another strategy with great potential is the use of adult stem cells, which could be expanded in culture and then utilized to engineer retinal tissue. In this study, we have explored a spontaneously immortalized human retinal progenitor cell line for its potential in retinal engineering using rotary cultures to generate three-dimensional (3D) structures. Retinal progenitors cultured alone or cocultured with retinal pigment epithelial cells form aggregates. The aggregate size increases between days 1 and 10. The cells grown as a 3D culture rotary system, which promotes cell-cell interaction, retain a spectrum of differentiation capability. Photoreceptor differentiation in these cultures is confirmed by significant upregulation of rhodopsin and AaNat, an enzyme implicated in melatonin synthesis (immunohistochemistry and Western blot analysis). Photoreceptor induction and differentiation is further attested to by the upregulation of rod transcription factor Nrl, Nr(2)e(3), expression of interstitial retinal binding protein, and rhodopsin kinase by reverse transcription-polymerase chain reaction. Differentiation toward other cell lineages is confirmed by the expression of tyrosine hydroxylase in amacrine cells, thy 1.1 expression in ganglion cells and calbindin, and GNB3 expression in cone cells. The capability of retinal progenitors to give rise to several retinal cell types when grown as aggregated cells in rotary culture offers hope that progenitor stem cells under appropriate culture conditions will be valuable to engineer retinal constructs, which could be further tested for their transplant potential. The fidelity with which this multipotential cell line retains its capacity to differentiate into multiple cell types holds great promise for the use of tissue-specific adult stem cells for therapy.
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Affiliation(s)
- Kamla Dutt
- Department of Pathology, Morehouse School of Medicine, Atlanta, Georgia 30310-1495, USA.
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Wang NK, Fine HF, Chang S, Chou CL, Cella W, Tosi J, Lin CS, Nagasaki T, Tsang SH. Cellular origin of fundus autofluorescence in patients and mice with a defective NR2E3 gene. Br J Ophthalmol 2009; 93:1234-40. [PMID: 19429590 PMCID: PMC2742679 DOI: 10.1136/bjo.2008.153577] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AIM To characterise new clinical features in a family with enhanced S-cone syndrome (ESCS) and investigate the pathogenesis of these clinical features in the homozygous Nr2e3(rd7) (rd7) mutant mice. METHODS Four patients from an affected family were included for genotypic and phenotypic study. Eye tissues from rd7 mice were used to detect a possible relationship between macrophages and autofluorescent material by immunohistochemistry (IHC) staining. RESULTS Homozygous mutation in R311Q in NR2E3 was detected in this family. Colour photographs revealed that white dots do not correlate to hyperautofluorescent spots seen in autofluorescence imaging of the macula. OCT showed rosette-like lesions similar to those found in rd7 mice histology sections. From IHC analysis, we observed that F4/80 (a pan macrophage marker) and autofluorescence were colocalised to the same cells within the retina rosettes. CONCLUSIONS The retinal structure of a young ESCS patient with homozygous R311Q mutation in the NR2E3 gene is similar to that seen in the rd7 mice. The macrophages were found to contain autofluorescent materials in the retinal rosettes of rd7 mice. These data are consistent with macrophage infiltration contributing to the hyperautofluorescent spots found in our patients.
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Affiliation(s)
- N-K Wang
- Bernard & Shirlee Brown Glaucoma Laboratory, Edward S Harkness Eye Institute, New York 10032, USA
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Escher P, Gouras P, Roduit R, Tiab L, Bolay S, Delarive T, Chen S, Tsai CC, Hayashi M, Zernant J, Merriam JE, Mermod N, Allikmets R, Munier FL, Schorderet DF. Mutations in NR2E3 can cause dominant or recessive retinal degenerations in the same family. Hum Mutat 2009; 30:342-51. [PMID: 19006237 DOI: 10.1002/humu.20858] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
NR2E3, a photoreceptor-specific nuclear receptor (PNR), represses cone-specific genes and activates several rod-specific genes. In humans, mutations in NR2E3 have been associated with the recessively-inherited enhanced short-wavelength sensitive S-cone syndrome (ESCS) and, recently, with autosomal dominant (ad) retinitis pigmentosa (RP) (adRP). In the present work, we describe two additional families affected by adRP that carry a heterozygous c.166G>A (p.G56R) mutation in the NR2E3 gene. Functional analysis determined the dominant negative activity of the p.G56R mutant protein as the molecular mechanism of adRP. Interestingly, in one pedigree, the most common causal variant for ESCS (p.R311Q) cosegregated with the adRP-linked p.G56R mutation, and the compound heterozygotes exhibited an ESCS-like phenotype, which in 1 of the 2 cases was strikingly "milder" than the patients carrying the p.G56R mutation alone. Impaired repression of cone-specific genes by the corepressors atrophin-1 (dentatorubral-pallidoluysian atrophy [DRPLA] gene product) and atrophin-2 (arginine-glutamic acid dipeptide repeat [RERE] protein) appeared to be a molecular mechanism mediating the beneficial effect of the p.R311Q mutation. Finally, the functional dominance of the p.R311Q variant to the p.G56R mutation is discussed.
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Affiliation(s)
- Pascal Escher
- Institut de Recherche en Ophtalmologie, Sion, Switzerland
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Haider NB, Mollema N, Gaule M, Yuan Y, Sachs AJ, Nystuen AM, Naggert JK, Nishina PM. Nr2e3-directed transcriptional regulation of genes involved in photoreceptor development and cell-type specific phototransduction. Exp Eye Res 2009; 89:365-72. [PMID: 19379737 DOI: 10.1016/j.exer.2009.04.006] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2008] [Revised: 04/06/2009] [Accepted: 04/06/2009] [Indexed: 10/20/2022]
Abstract
The retinal transcription factor Nr2e3 plays a key role in photoreceptor development and function. In this study we examine gene expression in the retina of Nr2e3(rd7/rd7) mutants with respect to wild-type control mice, to identify genes that are misregulated and hence potentially function in the Nr2e3 transcriptional network. Quantitative candidate gene real time PCR and subtractive hybridization approaches were used to identify transcripts that were misregulated in Nr2e3(rd7/rd7) mice. Chromatin immunoprecipitation assays were then used to determine which of the misregulated transcripts were direct targets of NR2E3. We identified 24 potential targets of NR2E3. In the developing retina, NR2E3 targets transcription factors such as Ror1, Rorg, and the nuclear hormone receptors Nr1d1 and Nr2c1. In the mature retina NR2E3 targets several genes including the rod specific gene Gnb1 and cone specific genes blue opsin, and two of the cone transducin subunits, Gnat2 and Gnb3. In addition, we identified 5 novel transcripts that are targeted by NR2E3. While mislocalization of proteins between rods and cones was not observed, we did observe diminished concentration of GNB1 protein in adult Nr2e3(rd7/rd7) retinas. These studies identified novel transcriptional pathways that are potentially targeted by Nr2e3 in the retina and specifically demonstrate a novel role for NR2E3 in regulating genes involved in phototransduction.
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Affiliation(s)
- Neena B Haider
- Department of Genetics, Cell Biology, and Anatomy, University of Nebraska Medical Center, 985805 Nebraska Medical Center, Omaha, NE 68198-5805, USA.
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Naturally occurring animal models with outer retina phenotypes. Vision Res 2009; 49:2636-52. [PMID: 19375447 DOI: 10.1016/j.visres.2009.04.008] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2009] [Revised: 04/07/2009] [Accepted: 04/07/2009] [Indexed: 01/28/2023]
Abstract
Naturally occurring and laboratory generated animal models serve as powerful tools with which to investigate the etiology of human retinal degenerations, especially retinitis pigmentosa (RP), Leber congenital amaurosis (LCA), cone dystrophies (CD) and macular degeneration (MD). Much progress has been made in elucidating gene defects underlying disease, in understanding mechanisms leading to disease, and in designing molecules for translational research and gene-based therapy to interfere with the progression of disease. Key to this progress has been study of naturally occurring murine and canine retinal degeneration mutants. This article will review the history, phenotypes and gene defects of select animal models with outer retina (photoreceptor and retinal pigment epithelium) degeneration phenotypes.
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Abstract
In the developing retina the nuclear hormone receptor Nr2e3 has dual roles, promoting expression of rod-specific genes and repressing expression of cone specific genes. In a recent issue of Neuron, Onishi et al. show that PIAS3-mediated SUMOylation of Nr2e3 plays an essential role in the specification of rod photoreceptors by converting Nr2e3 to a potent repressor of cone gene expression.
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Khan AO, Aldahmesh M, Meyer B. The enhanced S-cone syndrome in children. BMJ Case Rep 2009; 2009:bcr10.2008.1163. [PMID: 21686439 DOI: 10.1136/bcr.10.2008.1163] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
The enhanced S-cone syndrome (ESCS), a rare retinal degenerative disease often associated with NR2E3 mutation, is due to increased numbers of S-cones at the expense of other photoreceptors or miswiring distal to the photoreceptors. Paediatric ESCS and its differing clinical features (as opposed to adult ESCS) is the subject of this report.
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Affiliation(s)
- Arif O Khan
- Division of Pediatric Ophthalmology, King Khaled Eye Specialist Hospital, Riyadh, Saudi Arabia
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Langmann T, Lai CCL, Weigelt K, Tam BM, Warneke-Wittstock R, Moritz OL, Weber BHF. CRX controls retinal expression of the X-linked juvenile retinoschisis (RS1) gene. Nucleic Acids Res 2008; 36:6523-34. [PMID: 18927113 PMCID: PMC2582616 DOI: 10.1093/nar/gkn737] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
X-linked juvenile retinoschisis is a heritable condition of the retina in males caused by mutations in the RS1 gene. Still, the cellular function and retina-specific expression of RS1 are poorly understood. To address the latter issue, we characterized the minimal promoter driving expression of RS1 in the retina. Binding site prediction, site-directed mutagenesis, and reporter assays suggest an essential role of two nearby cone-rod homeobox (CRX)-responsive elements (CRE) in the proximal −177/+32 RS1 promoter. Chromatin immunoprecipitation associates the RS1 promoter in vivo with CRX, the coactivators CBP, P300, GCN5 and acetylated histone H3. Transgenic Xenopus laevis expressing a green fluorescent protein (GFP) reporter under the control of RS1 promoter sequences show that the −177/+32 fragment drives GFP expression in photoreceptors and bipolar cells. Mutating either of the two conserved CRX binding sites results in strongly decreased RS1 expression. Despite the presence of sequence motifs in the promoter, NRL and NR2E3 appear not to be essential for RS1 expression. Together, our in vitro and in vivo results indicate that two CRE sites in the minimal RS1 promoter region control retinal RS1 expression and establish CRX as a key factor driving this expression.
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Affiliation(s)
- Thomas Langmann
- Institute of Human Genetics, University of Regensburg, Regensburg, Germany
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Nystuen AM, Sachs AJ, Yuan Y, Heuermann L, Haider NB. A novel mutation in Prph2, a gene regulated by Nr2e3, causes retinal degeneration and outer-segment defects similar to Nr2e3 ( rd7/rd7 ) retinas. Mamm Genome 2008; 19:623-33. [PMID: 18763016 DOI: 10.1007/s00335-008-9138-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2008] [Accepted: 07/08/2008] [Indexed: 12/11/2022]
Abstract
The nmf193 mutant was generated by a large-scale ENU mutagenesis screen and originally described as having a dominantly inherited phenotype characterized by fundus abnormalities. We determined that nmf193 mice exhibit outer-segment defects and progressive retinal degeneration. Clinical examination revealed retinal spotting apparent at 6 weeks of age. Histologic analysis of homozygous mutant mice at 6 weeks indicated an absence of outer segments (OS) and a 50% reduction of photoreceptor cells which progressed to complete loss of photoreceptors by 10 months. Mice heterozygous for the nmf193 mutation had a less severe phenotype of shortened outer segments at 2 months with progressive loss of photoreceptor cells to 50% by 10 months. A positional cloning approach using a DNA pooling strategy was performed to identify the causative mutation in nmf193 mice. The nmf193 mutation was linked to chromosome 17 and fine mapped to an interval containing the peripherin/rds (Prph2) gene. Mutation analysis identified a single base change in Prph2 that causes aberrant splicing between exons 1 and 2. Interestingly, a comparative histologic analysis demonstrated that Prph2 ( nmf193/+ ) mutants have similar photoreceptor degeneration to that of Nr2e3 ( rd7/rd7 ). We show that Prph2 mRNA and protein levels are reduced in the Nr2e3 ( rd7/rd7 ) mutant compared to control littermates. Chromatin immunoprecipitation analysis shows that Prph2 is a direct target of NR2E3. In addition, the downregulation of Prph2 gene expression is similar in both the Nr2e3 ( rd7/rd7 ) and Prph2 ( nmf193/+ ) mutants, suggesting that the reduction of Prph2 may contribute to the degenerative pathology seen in Nr2e3 ( rd7/rd7 ).
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Affiliation(s)
- Arne M Nystuen
- The Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE, 68198-5805, USA
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83
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Webber AL, Hodor P, Thut CJ, Vogt TF, Zhang T, Holder DJ, Petrukhin K. Dual role of Nr2e3 in photoreceptor development and maintenance. Exp Eye Res 2008; 87:35-48. [PMID: 18547563 DOI: 10.1016/j.exer.2008.04.006] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2008] [Revised: 04/10/2008] [Accepted: 04/16/2008] [Indexed: 11/17/2022]
Abstract
Nr2e3 is a photoreceptor-specific nuclear receptor believed to play a role in photoreceptor development, differentiation, and survival. Much research has focused on the interaction of Nr2e3 with other transcription factors in determining the milieu of target gene expression in photoreceptors of the neonatal and adult retina. To investigate the downstream targets of Nr2e3 and thereby shed light on the functional pathways relevant to photoreceptor development and maintenance, expression profiling was performed on retinas from two different mouse knockout lines, one containing a targeted disruption of the Nr2e3 gene (Nr2e3 -/-), the other containing a spontaneous null allele of the Nr2e3 locus (rd7). Using whole genome microarrays, mRNA expression profiles of retinas from the two mutant strains were compared to those of wildtype C57BL/6 mice over a time course that ranged from postnatal day (p) 2 to 6months of age (p180). Additionally, expression profiling was performed on retinal explants treated with a putative NR2E3 agonist. The molecular profiling of Nr2e3 -/- and rd7/rd7 retinas identified 281 putative Nr2e3-dependent genes that were differentially expressed between wildtype and mutant retinas during at least one time point. Consistent with previous reports that Nr2e3 is necessary for the repression of cone-specific genes, increased expression of cone-specific genes was observed in the mutant samples, thereby providing proof-of-concept for the microarray screen. Further annotation of these data sets revealed ten predominant functional classes involved in the Nr2e3-mediated development and/or maintenance of photoreceptors. Interestingly, differences in the expression of Nr2e3-dependent genes exhibited two distinct temporal patterns. One group of genes showed a sustained difference in expression as compared to wildtype over the entire time course of the study, whereas a second group showed only transient differences which were largest around p10. Comparison of gene expression changes in Nr2e3 -/- and rd7/rd7 retinas with those uncovered by treating retinal explants with a putative NR2E3 agonist revealed four genes that were down-regulated in mutant retinas that lack Nr2e3 function but were up-regulated in agonist-treated explants. These results strongly suggest that the four genes may be direct targets of Nr2e3. Our identification of two sets of Nr2e3-regulated genes provides further evidence of a dual role for Nr2e3 in specification of photoreceptor fate during development as well as photoreceptor maintenance in the adult.
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Affiliation(s)
- Andrea L Webber
- Department of Ophthalmology, Merck & Co Inc, West Point, PA 19486, USA.
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84
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Mapping of genetic modifiers of Nr2e3 rd7/rd7 that suppress retinal degeneration and restore blue cone cells to normal quantity. Mamm Genome 2008; 19:145-54. [PMID: 18286335 DOI: 10.1007/s00335-008-9092-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2007] [Accepted: 12/18/2007] [Indexed: 10/22/2022]
Abstract
The retinal degeneration 7 (rd7) mouse, lacking expression of the Nr2e3 gene, exhibits retinal dysplasia and a slow, progressive degeneration due to an abnormal production of blue opsin-expressing cone cells. In this study we evaluated three strains of mice to identify alleles that would slow or ameliorate the retinal degeneration observed in Nr2e3 (rd7/rd7) mice. Our studies reveal that genetic background greatly influences the expression of the Nr2e3 (rd7/rd7) phenotype and that the inbred mouse strains CAST/EiJ, AKR/J, and NOD.NON-H2 (nb1) carry alleles that confer resistance to Nr2e3 (rd7/rd7)-induced retinal degeneration. B6.Cg-Nr2e3 (rd7/rd7) mice were outcrossed to each strain and the F(1) progeny were intercrossed to produce F(2) mice. In each intercross, 20-24% of the total F(2) progeny were homozygous for the Nr2e3 (rd7/rd7) mutation in a mixed genetic background; approximately 28-48% of the Nr2e3 (rd7/rd7) homozygotes were suppressed for the degenerative retina phenotype in a mixed genetic background. The suppressed mice had no retinal spots and normal retinal morphology with a normal complement of blue opsin-expressing cone cells. An initial genome scan revealed a significant association of the suppressed phenotype with loci on chromosomes 8 and 19 with the CAST/EiJ background, two marginal loci on chromosomes 7 and 11 with the AKR/J background, and no significant QTL with the NOD.NON-H2 (nb1) background. We did not observe any significant epistatic effects in this study. Our results suggest that there are several genes that are likely to act in the same or parallel pathway as NR2E3 that can rescue the Nr2e3 (rd7/rd7) phenotype and may serve as potential therapeutic targets.
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85
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Oh ECT, Cheng H, Hao H, Jia L, Khan NW, Swaroop A. Rod differentiation factor NRL activates the expression of nuclear receptor NR2E3 to suppress the development of cone photoreceptors. Brain Res 2008; 1236:16-29. [PMID: 18294621 DOI: 10.1016/j.brainres.2008.01.028] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2007] [Revised: 12/21/2007] [Accepted: 01/09/2008] [Indexed: 01/22/2023]
Abstract
Neural developmental programs require a high level of coordination between the decision to exit cell cycle and acquisition of cell fate. The Maf-family transcription factor NRL is essential for rod photoreceptor specification in the mammalian retina as its loss of function converts rod precursors to functional cones. Ectopic expression of NRL or a photoreceptor-specific orphan nuclear receptor NR2E3 completely suppresses cone development while concurrently directing the post-mitotic photoreceptor precursors towards rod cell fate. Given that NRL and NR2E3 have overlapping functions and NR2E3 expression is abolished in the Nrl(-/-) retina, we wanted to clarify the distinct roles of NRL and NR2E3 during retinal differentiation. Here, we demonstrate that NRL binds to a sequence element in the Nr2e3 promoter and enhances its activity synergistically with the homeodomain protein CRX. Using transgenic mice, we show that NRL can only partially suppress cone development in the absence of NR2E3. Gene profiling of retinas from transgenic mice that ectopically express NR2E3 or NRL in cone precursors reveals overlapping and unique targets of these two transcription factors. Together with previous reports, our findings establish the hierarchy of transcriptional regulators in determining rod versus cone cell fate in photoreceptor precursors during the development of mammalian retina.
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Affiliation(s)
- Edwin C T Oh
- Program in Neuroscience, University of Michigan, Ann Arbor MI, USA
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86
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McIlvain VA, Knox BE. Nr2e3 and Nrl can reprogram retinal precursors to the rod fate in Xenopus retina. Dev Dyn 2007; 236:1970-9. [PMID: 17377979 DOI: 10.1002/dvdy.21128] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Transformation of undifferentiated progenitors into specific cell types is largely dependent on temporal and spatial expression of a complex network of transcription factors. Here, we examined whether neural retina leucine zipper (Nrl) and photoreceptor-specific nuclear receptor Nr2e3 transcription factors contribute to cell fate determination. We cloned the Xenopus Nr2e3 gene and showed that its temporal and spatial expression is similar to its mammalian ortholog. We tested its in vivo function by misexpressing these transcription factors in Xenopus eye primordia, demonstrating that either human Nr2e3 or Nrl directed photoreceptor precursors to become rods at the expense of cones. Furthermore, overexpression of Xenopus Nrl dramatically increased the number of lens fibers, whereas human Nrl did not, suggesting evolutionary divergence of function of the Nrl gene family. Misexpression of Nrl and Nr2e3 together were more effective than either transcription factor alone in directing precursors to the rod fate.
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Affiliation(s)
- Vera A McIlvain
- Department of Biochemistry & Molecular Biology and Ophthalmology, SUNY Upstate Medical University, Syracuse, New York 13210, USA
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87
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Hsiau THC, Diaconu C, Myers CA, Lee J, Cepko CL, Corbo JC. The cis-regulatory logic of the mammalian photoreceptor transcriptional network. PLoS One 2007; 2:e643. [PMID: 17653270 PMCID: PMC1916400 DOI: 10.1371/journal.pone.0000643] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2007] [Accepted: 06/19/2007] [Indexed: 12/28/2022] Open
Abstract
The photoreceptor cells of the retina are subject to a greater number of genetic diseases than any other cell type in the human body. The majority of more than 120 cloned human blindness genes are highly expressed in photoreceptors. In order to establish an integrative framework in which to understand these diseases, we have undertaken an experimental and computational analysis of the network controlled by the mammalian photoreceptor transcription factors, Crx, Nrl, and Nr2e3. Using microarray and in situ hybridization datasets we have produced a model of this network which contains over 600 genes, including numerous retinal disease loci as well as previously uncharacterized photoreceptor transcription factors. To elucidate the connectivity of this network, we devised a computational algorithm to identify the photoreceptor-specific cis-regulatory elements (CREs) mediating the interactions between these transcription factors and their target genes. In vivo validation of our computational predictions resulted in the discovery of 19 novel photoreceptor-specific CREs near retinal disease genes. Examination of these CREs permitted the definition of a simple cis-regulatory grammar rule associated with high-level expression. To test the generality of this rule, we used an expanded form of it as a selection filter to evolve photoreceptor CREs from random DNA sequences in silico. When fused to fluorescent reporters, these evolved CREs drove strong, photoreceptor-specific expression in vivo. This study represents the first systematic identification and in vivo validation of CREs in a mammalian neuronal cell type and lays the groundwork for a systems biology of photoreceptor transcriptional regulation.
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Affiliation(s)
- Timothy H.-C. Hsiau
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Claudiu Diaconu
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Connie A. Myers
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Jongwoo Lee
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Constance L. Cepko
- Howard Hughes Medical Institute, Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
- * To whom correspondence should be addressed. E-mail: (CC); (JC)
| | - Joseph C. Corbo
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- * To whom correspondence should be addressed. E-mail: (CC); (JC)
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88
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Hennig AK, Peng GH, Chen S. Regulation of photoreceptor gene expression by Crx-associated transcription factor network. Brain Res 2007; 1192:114-33. [PMID: 17662965 PMCID: PMC2266892 DOI: 10.1016/j.brainres.2007.06.036] [Citation(s) in RCA: 155] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2007] [Revised: 06/13/2007] [Accepted: 06/20/2007] [Indexed: 01/31/2023]
Abstract
Rod and cone photoreceptors in the mammalian retina are special types of neurons that are responsible for phototransduction, the first step of vision. Development and maintenance of photoreceptors require precisely regulated gene expression. This regulation is mediated by a network of photoreceptor transcription factors centered on Crx, an Otx-like homeodomain transcription factor. The cell type (subtype) specificity of this network is governed by factors that are preferentially expressed by rods or cones or both, including the rod-determining factors neural retina leucine zipper protein (Nrl) and the orphan nuclear receptor Nr2e3; and cone-determining factors, mostly nuclear receptor family members. The best-documented of these include thyroid hormone receptor beta2 (Tr beta2), retinoid related orphan receptor Ror beta, and retinoid X receptor Rxr gamma. The appropriate function of this network also depends on general transcription factors and cofactors that are ubiquitously expressed, such as the Sp zinc finger transcription factors and STAGA co-activator complexes. These cell type-specific and general transcription regulators form complex interactomes; mutations that interfere with any of the interactions can cause photoreceptor development defects or degeneration. In this manuscript, we review recent progress on the roles of various photoreceptor transcription factors and interactions in photoreceptor subtype development. We also provide evidence of auto-, para-, and feedback regulation among these factors at the transcriptional level. These protein-protein and protein-promoter interactions provide precision and specificity in controlling photoreceptor subtype-specific gene expression, development, and survival. Understanding these interactions may provide insights to more effective therapeutic interventions for photoreceptor diseases.
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Affiliation(s)
- Anne K. Hennig
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110
| | - Guang-Hua Peng
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110
| | - Shiming Chen
- Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110
- Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, MO 63110
- Corresponding Author: Shiming Chen, Ph.D., Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8096, St. Louis, MO 63110. Phone: (314) 747−4350; Fax: (314) 747−4211;
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89
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Haider NB, Demarco P, Nystuen AM, Huang X, Smith RS, McCall MA, Naggert JK, Nishina PM. The transcription factor Nr2e3 functions in retinal progenitors to suppress cone cell generation. Vis Neurosci 2007; 23:917-29. [PMID: 17266784 DOI: 10.1017/s095252380623027x] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2006] [Accepted: 10/20/2006] [Indexed: 12/27/2022]
Abstract
The transcription factor Nr2e3 is an essential component for development and specification of rod and cone photoreceptors; however, the mechanism through which it acts is not well understood. In this study, we use Nr2e3(rd7/rd7) mice that harbor a mutation in Nr2e3, to serve as a model for the human retinal disease Enhanced S Cone Syndrome. Our studies reveal that NR2E3 is expressed in late retinal progenitors and differentiating photoreceptors of the developing retina and localized to the cell bodies of mature rods and cones. In particular, we demonstrate that the abnormal increase in cone photoreceptors observed in Nr2e3(rd7/rd7) mice arise from ectopic mitotic progenitor cells that are present in the outer nuclear layer of the mature Nr2e3(rd7/rd7) retina. A prolonged phase of proliferation is observed followed by abnormal retinal lamination with fragmented and disorganized photoreceptor synapses that result in a progressive loss of rod and cone function. An extended and pronounced wave of apoptosis is also detected at P30 and temporally correlates with the phase of prolonged proliferation. Approximately twice as many apoptotic cells were detected compared to proliferating cells. This wave of apoptosis appears to affect both rod and cone cells and thus may account for the concurrent loss of rod and cone function. We further show that Nr2e3(rd7/rd7) cones do not express rod specific genes and Nr2e3(rd7/rd7) rods do not express cone specific genes. Our studies suggest that, based on its temporal and spatial expression, NR2E3 acts simultaneously in different cell types: in late mitotic progenitors, newly differentiating post mitotic cells, and mature rods and cones. In particular, this study reveals the function of NR2E3 in mitotic progenitors is to repress the cone generation program. NR2E3 is thus one of the few genes known to influence the competency of retinal progenitors while simultaneously directing the rod and cone differentiation.
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MESH Headings
- Adaptation, Ocular/genetics
- Animals
- Animals, Newborn
- Bromodeoxyuridine/metabolism
- Electroretinography/methods
- Embryo, Mammalian
- Eye Proteins/metabolism
- Gene Expression Regulation, Developmental/genetics
- In Situ Nick-End Labeling/methods
- Ki-67 Antigen/metabolism
- Mice
- Mice, Inbred C57BL
- Mice, Transgenic
- Microscopy, Electron, Transmission/methods
- Orphan Nuclear Receptors
- RNA, Messenger/biosynthesis
- Receptors, Cytoplasmic and Nuclear/genetics
- Receptors, Cytoplasmic and Nuclear/physiology
- Retina/cytology
- Retinal Cone Photoreceptor Cells/physiology
- Retinal Cone Photoreceptor Cells/ultrastructure
- Retinal Degeneration/genetics
- Reverse Transcriptase Polymerase Chain Reaction/methods
- Stem Cells/physiology
- Stem Cells/ultrastructure
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Affiliation(s)
- Neena B Haider
- Department of Genetics, University of Nebraska Medical Center, Omaha, Nebraska 68198, USA.
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90
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91
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Adler R, Raymond PA. Have we achieved a unified model of photoreceptor cell fate specification in vertebrates? Brain Res 2007; 1192:134-50. [PMID: 17466954 PMCID: PMC2288638 DOI: 10.1016/j.brainres.2007.03.044] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2007] [Revised: 03/08/2007] [Accepted: 03/16/2007] [Indexed: 12/01/2022]
Abstract
How does a retinal progenitor choose to differentiate as a rod or a cone and, if it becomes a cone, which one of their different subtypes? The mechanisms of photoreceptor cell fate specification and differentiation have been extensively investigated in a variety of animal model systems, including human and non-human primates, rodents (mice and rats), chickens, frogs (Xenopus) and fish. It appears timely to discuss whether it is possible to synthesize the resulting information into a unified model applicable to all vertebrates. In this review we focus on several widely used experimental animal model systems to highlight differences in photoreceptor properties among species, the diversity of developmental strategies and solutions that vertebrates use to create retinas with photoreceptors that are adapted to the visual needs of their species, and the limitations of the methods currently available for the investigation of photoreceptor cell fate specification. Based on these considerations, we conclude that we are not yet ready to construct a unified model of photoreceptor cell fate specification in the developing vertebrate retina.
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Affiliation(s)
| | - Pamela A. Raymond
- Department of Molecular, Cellular and Developmental Biology, University of Michigan
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92
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Takezawa S, Yokoyama A, Okada M, Fujiki R, Iriyama A, Yanagi Y, Ito H, Takada I, Kishimoto M, Miyajima A, Takeyama KI, Umesono K, Kitagawa H, Kato S. A cell cycle-dependent co-repressor mediates photoreceptor cell-specific nuclear receptor function. EMBO J 2007; 26:764-74. [PMID: 17255935 PMCID: PMC1794400 DOI: 10.1038/sj.emboj.7601548] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2006] [Accepted: 12/15/2006] [Indexed: 01/30/2023] Open
Abstract
Photoreceptor cell-specific nuclear receptor (PNR) (NR2E3) acts as a sequence-specific repressor that controls neuronal differentiation in the developing retina. We identified a novel PNR co-repressor, Ret-CoR, that is expressed in the developing retina and brain. Biochemical purification of Ret-CoR identified a multiprotein complex that included E2F/Myb-associated proteins, histone deacetylases (HDACs) and NCoR/HDAC complex-related components. Ret-CoR appeared to function as a platform protein for the complex, and interacted with PNR via two CoRNR motifs. Purified Ret-CoR complex exhibited HDAC activity, co-repressed PNR transrepression function in vitro, and co-repressed PNR function in PNR target gene promoters, presumably in the retinal progenitor cells. Notably, the appearance of Ret-CoR protein was cell-cycle-stage-dependent (from G1 to S). Therefore, Ret-CoR appears to act as a component of an HDAC co-repressor complex that supports PNR repression function in the developing retina, and may represent a co-regulator class that supports transcriptional regulator function via cell-cycle-dependent expression.
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Affiliation(s)
- Shinichiro Takezawa
- The Institute of Molecular and Cellular Biosciences, University of Tokyo, Bunkyo-ku, Tokyo, Japan
- ERATO, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan
| | - Atsushi Yokoyama
- The Institute of Molecular and Cellular Biosciences, University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Maiko Okada
- The Institute of Molecular and Cellular Biosciences, University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Ryoji Fujiki
- The Institute of Molecular and Cellular Biosciences, University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Aya Iriyama
- Department of Ophthalmology, University of Tokyo, School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Yasuo Yanagi
- Department of Ophthalmology, University of Tokyo, School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Hiroaki Ito
- The Institute of Molecular and Cellular Biosciences, University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Ichiro Takada
- The Institute of Molecular and Cellular Biosciences, University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Masahiko Kishimoto
- The Institute of Molecular and Cellular Biosciences, University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Atsushi Miyajima
- The Institute of Molecular and Cellular Biosciences, University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Ken-ichi Takeyama
- The Institute of Molecular and Cellular Biosciences, University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Kazuhiko Umesono
- Institute for Virus Research, and Graduate School for Biostudies, Kyoto University, Kyoto, Japan
| | - Hirochika Kitagawa
- The Institute of Molecular and Cellular Biosciences, University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Shigeaki Kato
- The Institute of Molecular and Cellular Biosciences, University of Tokyo, Bunkyo-ku, Tokyo, Japan
- ERATO, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan
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93
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Kitambi SS, Hauptmann G. The zebrafish orphan nuclear receptor genes nr2e1 and nr2e3 are expressed in developing eye and forebrain. Gene Expr Patterns 2007; 7:521-8. [PMID: 17127102 DOI: 10.1016/j.modgep.2006.10.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2006] [Revised: 10/12/2006] [Accepted: 10/16/2006] [Indexed: 11/24/2022]
Abstract
Mammalian Nr2e1 (Tailless, Mtll or Tlx) and Nr2e3 (photoreceptor-specific nuclear receptor, Pnr) are highly related orphan nuclear receptors, that are expressed in eye and forebrain-derived structures. In this study, we analyzed the developmental expression patterns of zebrafish nr2e1 and nr2e3. RT-PCR analysis showed that nr2e1 and nr2e3 are both expressed during embryonic and post-embryonic development. To examine the spatial distribution of nr2e1 and nr2e3 during development whole-mount in situ hybridization was performed. At tailbud stage, initial nr2e1 expression was localized to the rostral brain rudiment anterior to pax2.1 and eng2 expression at the prospective midbrain-hindbrain boundary. During subsequent stages, nr2e1 became widely expressed in fore- and midbrain primordia, eye and olfactory placodes. At 24hpf, strong nr2e1 expression was detected in telencephalon, hypothalamus, dorsal thalamus, pretectum, midbrain tectum, and retina. At 2dpf, the initially widespread nr2e1 expression became more restricted to distinct regions within the fore- and midbrain and to the retinal ciliary margin, the germinal zone which gives rise to retina and presumptive iris. Expression of nr2e3 was exclusively found in the developing retina and epiphysis. In both structures, nr2e3 expression was found in photoreceptor cells. The developmental expression profile of zebrafish nr2e1 and nr2e3 is consistent with evolutionary conserved functions in eye and rostral brain structures.
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Affiliation(s)
- Satish Srinivas Kitambi
- School of Life Sciences, Södertörns University College, Department of Biosciences and Nutrition, Karolinska Institutet, Alfred Nobels Allé 3, 14152 Huddinge, Sweden
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94
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Mali RS, Zhang X, Hoerauf W, Doyle D, Devitt J, Loffreda-Wren J, Mitton KP. FIZ1 is expressed during photoreceptor maturation, and synergizes with NRL and CRX at rod-specific promoters in vitro. Exp Eye Res 2006; 84:349-60. [PMID: 17141759 PMCID: PMC5066392 DOI: 10.1016/j.exer.2006.10.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2006] [Revised: 09/23/2006] [Accepted: 10/13/2006] [Indexed: 01/12/2023]
Abstract
FIZ1 (Flt-3 Interacting Zinc-finger) interacts and co-purifies with the rod-specific transcription factor NRL (Neural Retina Leucine zipper). We hypothesize that FIZ1 is part of an interface between cell-specific factors, like NRL, and more ubiquitous regulatory networks that vary the absolute expression levels of some rod-specific genes (i.e. Rhodopsin). As part of an ongoing exploration of FIZ1's role in neural retina, in vivo, we have taken the first look at FIZ1 expression in the developing mouse retina during the retinal maturation period. Using the normal C57B6 mouse as a model, multiple approaches were used including: immunoblotting, immunohistochemistry, and quantitative real-time PCR. Functional implications of FIZ1/NRL interaction, on NRL- and CRX-mediated activation of the Rhodopsin (Rho) and cGMP-phosphodiesterase beta-subunit gene (PDE6B) promoters, were examined by co-transfection assays. Immunoblot analysis revealed that FIZ1 protein levels were lowest in immature mouse neural retina (P0). FIZ1 concentration increased at least ten-fold as the neural retina matured to the adult state (P21 and later). Immunohistochemical comparison of immature post-natal and mature adult retina revealed increasing FIZ1 protein in photoreceptors, the inner plexiform layer, and the ganglion cell layer. Total retinal Fiz1 mRNA content increased as the neural retina matured. The expected increase in Rho mRNA level was also monitored as a genetic marker of photoreceptor maturation. In transient co-transfection assays of CV1 cells, FIZ1 synergized with NRL to activate transcription from the Rho and PDE6B gene promoters with some differences. In the case of the Rho promoter, FIZ1 synergized when both NRL and CRX were present. With the PDE6B promoter, FIZ1 synergized with NRL alone, and the inclusion of CRX decreased this synergy. These findings support previous evidence that FIZ1 is present in rod-photoreceptors (co-immunoprecipitation from nuclear-protein extracts with rod-specific NRL). FIZ1 expression increases in the neural retina during the retinal maturation period. Additionally, in vitro experiments demonstrate that FIZ1 has the potential to significantly increase the NRL-mediated activation of photoreceptor-specific promoters. While CRX is not a strong activator of the PDE6B promoter, alone or with NRL, CRX decreased the synergy of NRL with FIZ1.
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Affiliation(s)
| | | | | | | | | | | | - Kenneth P. Mitton
- Corresponding Author: Kenneth P. Mitton, Ph.D., Assistant Professor of Biomedical Sciences, Oakland University Eye Research Institute, Rm 412 Dodge Hall, Oakland University, Rochester MI, 48309, 1-248-370-2079, Fax: 1-248-370-2006,
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95
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Nystuen AM, Schwendinger JK, Sachs AJ, Yang AW, Haider NB. A null mutation in VAMP1/synaptobrevin is associated with neurological defects and prewean mortality in the lethal-wasting mouse mutant. Neurogenetics 2006; 8:1-10. [PMID: 17102983 DOI: 10.1007/s10048-006-0068-7] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2006] [Accepted: 10/02/2006] [Indexed: 10/23/2022]
Abstract
The soluble N-ethylmaleimide sensitive factor attachment receptors are a large family of membrane-associated proteins that are critical for Ca(2+)-mediated synaptic vesicle release. This family includes the VAMP, synaptosomal-associated protein, and syntaxin proteins. In this report, we describe a mutation in vesicle-associated membrane protein 1(VAMP1)/synaptobrevin in the mouse neurological mutant lethal-wasting (lew). The lethal-wasting mutant phenotype is characterized by a general lack of movement and wasting, eventually leading to death before weaning. Mutants are visibly immobile and lay on their side by postnatal day 10 (P10). Before this stage, mutants can be identified by a failure to attempt to right themselves. Affected mice die on average at P15. We used a positional cloning strategy to identify the mutation associated with this neurological phenotype. Lethal wasting had previously been linked to chromosome 6. We further narrowed the genetic disease interval and selected a small number of candidate genes for mutation screening. Genes were evaluated by quantitative reverse transcription-polymerase chain reaction (RT-PCR) to detect differences in their expression levels between control and mutant brain ribonucleic acid (RNA) samples. VAMP1 mRNA was found to be significantly downregulated in the lethal-wasting brain compared to wild-type littermates. Subsequently, a nonsense mutation was identified in the coding region of the gene. This mutation is predicted to truncate approximately half of the protein; however, Western blot analysis showed that no protein is detectable in the mutant. VAMP1 is selectively expressed in the retina and in discrete areas of the brain including the zona incerta and rostral periolivary region, although no gross histological abnormalities were observed in these tissues. Taken together, these data indicate that VAMP1 has a vital role in a subset of central nervous system tissues.
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Affiliation(s)
- Arne M Nystuen
- Department of Genetics, Cell Biology and Anatomy, 6008 Durham Research Center, University of Nebraska Medical Center, Omaha, NE 68198, USA.
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96
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Wolkenberg SE, Zhao Z, Kapitskaya M, Webber AL, Petrukhin K, Tang YS, Dean DC, Hartman GD, Lindsley CW. Identification of potent agonists of photoreceptor-specific nuclear receptor (NR2E3) and preparation of a radioligand. Bioorg Med Chem Lett 2006; 16:5001-4. [PMID: 16879962 DOI: 10.1016/j.bmcl.2006.07.056] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2006] [Revised: 07/13/2006] [Accepted: 07/17/2006] [Indexed: 11/22/2022]
Abstract
Agonists of NR2E3 (PNR, RNR) have been identified and optimized to EC(50)< 200 nM. A tritiated analogue of one agonist was prepared to aid in the development of a binding assay.
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Affiliation(s)
- Scott E Wolkenberg
- Department of Medicinal Chemistry, Technology Enabled Synthesis Group, Merck & Co., Inc., PO Box 4, West Point, PA 19486, USA.
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97
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Turner BA, Sparrow J, Cai B, Monroe J, Mikawa T, Hempstead BL. TrkB/BDNF signaling regulates photoreceptor progenitor cell fate decisions. Dev Biol 2006; 299:455-65. [PMID: 17005175 PMCID: PMC2623246 DOI: 10.1016/j.ydbio.2006.08.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2005] [Revised: 08/07/2006] [Accepted: 08/09/2006] [Indexed: 10/24/2022]
Abstract
Neurotrophins, via activation of Trk receptor tyrosine kinases, serve as mitogens, survival factors and regulators of arborization during retinal development. Brain-derived neurotrophic factor (BDNF) and TrkB regulate neuronal arborization and survival in late retinal development. However, TrkB is expressed during early retinal development where its functions are unclear. To assess TrkB/BDNF actions in the early chick retina, replication-incompetent retroviruses were utilized to over-express a dominant negative truncated form of TrkB (trunc TrkB), or BDNF and effects were assessed at E15. Clones expressing trunc TrkB were smaller than controls, and proliferation and apoptosis assays suggest that decreased clone size correlated with increased cell death when BDNF/TrkB signaling was impaired. Analysis of clonal composition revealed that trunc TrkB over-expression decreased photoreceptor numbers (41%) and increased cell numbers in the middle third of the inner nuclear layer (INL) (23%). Conversely, BDNF over-expression increased photoreceptor numbers (25%) and decreased INL numbers (17%). Photoreceptors over-expressing trunc TrkB demonstrated no increase in apoptosis nor abnormalities in lamination suggesting that TrkB activation is not required for photoreceptor cell survival or migration. These studies suggest that TrkB signaling regulates commitment to and/or differentiation of photoreceptor cells from retinal progenitor cells, identifying a novel role for TrkB/BDNF in regulating cell fate decisions.
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Affiliation(s)
- Brian A. Turner
- Department of Medicine, Weill Medical College of Cornell University, New York, New York, 10021
| | - Janet Sparrow
- Department of Ophthalmology, Columbia University, New York, New York, 10032
| | - Bolin Cai
- Department of Ophthalmology, Columbia University, New York, New York, 10032
| | - Julie Monroe
- Department of Medicine, Weill Medical College of Cornell University, New York, New York, 10021
| | - Takashi Mikawa
- Department of Cell Biology, Weill Medical College of Cornell University, New York, New York, 10021
| | - Barbara L. Hempstead
- Department of Medicine, Weill Medical College of Cornell University, New York, New York, 10021
- *Author to whom to address correspondence: Barbara L. Hempstead, Department of Medicine, Weill Medical College of Cornell University, 1300 York Avenue, Room C606, New York, New York, 10021, phone: 212-746-6215, fax: 212-746-8647,
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98
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Cheng H, Aleman TS, Cideciyan AV, Khanna R, Jacobson SG, Swaroop A. In vivo function of the orphan nuclear receptor NR2E3 in establishing photoreceptor identity during mammalian retinal development. Hum Mol Genet 2006; 15:2588-602. [PMID: 16868010 PMCID: PMC1592580 DOI: 10.1093/hmg/ddl185] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Rod and cone photoreceptors in mammalian retina are generated from common pool(s) of neuroepithelial progenitors. NRL, CRX and NR2E3 are key transcriptional regulators that control photoreceptor differentiation. Mutations in NR2E3, a rod-specific orphan nuclear receptor, lead to loss of rods, increased density of S-cones and supernormal S-cone-mediated vision in humans. To better understand its in vivo function, NR2E3 was expressed ectopically in the Nrl-/- retina, where post-mitotic precursors fated to be rods develop into functional S-cones similar to the human NR2E3 disease. Expression of NR2E3 in the Nrl-/- retina completely suppressed cone differentiation and resulted in morphologically rod-like photoreceptors, which were however not functional. Gene profiling of FACS-purified photoreceptors confirmed the role of NR2E3 as a strong suppressor of cone genes but an activator of only a subset of rod genes (including rhodopsin) in vivo. Ectopic expression of NR2E3 in cone precursors and differentiating S-cones of wild-type retina also generated rod-like cells. The dual regulatory function of NR2E3 was not dependent upon the presence of NRL and/or CRX, but on the timing and level of its expression. Our studies reveal a critical role of NR2E3 in establishing functional specificity of NRL-expressing photoreceptor precursors during retinal neurogenesis.
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Affiliation(s)
- Hong Cheng
- Neuroscience Graduate Program
- Department of Ophthalmology and Visual Sciences, W.K. Kellogg Eye Center and
| | - Tomas S. Aleman
- Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, USA
| | | | - Ritu Khanna
- Department of Ophthalmology and Visual Sciences, W.K. Kellogg Eye Center and
| | | | - Anand Swaroop
- Neuroscience Graduate Program
- Department of Ophthalmology and Visual Sciences, W.K. Kellogg Eye Center and
- Department of Human Genetics, University of Michigan, 1000 Wall Street, Ann Arbor, MI 48105, USA and
- *To whom correspondence should be addressed: Tel: +1 7347633731; Fax: +1 7346470228;
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99
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Khanna H, Akimoto M, Siffroi-Fernandez S, Friedman JS, Hicks D, Swaroop A. Retinoic acid regulates the expression of photoreceptor transcription factor NRL. J Biol Chem 2006; 281:27327-34. [PMID: 16854989 PMCID: PMC1592579 DOI: 10.1074/jbc.m605500200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
NRL (neural retina leucine zipper) is a key basic motif-leucine zipper (bZIP) transcription factor, which orchestrates rod photoreceptor differentiation by activating the expression of rod-specific genes. The deletion of Nrl in mice results in functional cones that are derived from rod precursors. However, signaling pathways modulating the expression or activity of NRL have not been elucidated. Here, we show that retinoic acid (RA), a diffusible factor implicated in rod development, activates the expression of NRL in serum-deprived Y79 human retinoblastoma cells and in primary cultures of rat and porcine photoreceptors. The effect of RA is mimicked by TTNPB, a RA receptor agonist, and requires new protein synthesis. DNaseI footprinting and electrophoretic mobility shift assays (EMSA) using bovine retinal nuclear extract demonstrate that RA response elements (RAREs) identified within the Nrl promoter bind to RA receptors. Furthermore, in transiently transfected Y79 and HEK293 cells the activity of Nrl-promoter driving a luciferase reporter gene is induced by RA, and this activation is mediated by RAREs. Our data suggest that signaling by RA via RA receptors regulates the expression of NRL, providing a framework for delineating early steps in photoreceptor cell fate determination.
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Affiliation(s)
- Hemant Khanna
- From the Departments of Ophthalmology and Visual Sciences and
| | - Masayuki Akimoto
- From the Departments of Ophthalmology and Visual Sciences and
- Translational Research Center, Kyoto University Hospital, Sakyo-ku, Kyoto 606-8507, Japan, the
| | | | | | - David Hicks
- Laboratory of Neurobiological Rhythms, UMR CNRS 7518, Centre de Neurochimie, 67084 Strasbourg, France
| | - Anand Swaroop
- From the Departments of Ophthalmology and Visual Sciences and
- Human Genetics, University of Michigan, Ann Arbor, Michigan 48105, the
- Harold F. Falls Collegiate Professor and a recipient of RPB Senior Scientific Investigator award. To whom correspondence should be addressed: Dept. of Ophthalmology and Visual Sciences, W. K. Kellogg Eye Center, University of Michigan, 1000 Wall St., Ann Arbor, MI 48105. Tel.: 734-763-3731; Fax: 734-647-0228; E-mail:
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100
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Kapitskaya M, Cunningham ME, Lacson R, Kornienko O, Bednar B, Petrukhin K. Development of the High Throughput Screening Assay for Identification of Agonists of an Orphan Nuclear Receptor. Assay Drug Dev Technol 2006; 4:253-62. [PMID: 16834531 DOI: 10.1089/adt.2006.4.253] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Retina-specific nuclear receptor (RNR), also known as PNR and NR2E3, is an orphan nuclear receptor expressed exclusively in photoreceptor cells of the retina. Here we describe homogeneous cell-based resonance energy transfer assay for identification of RNR agonists using beta-lactamase as the reporter gene. Bacterial beta-lactamase reporter construct containing GAL4 response elements was randomly integrated into the genome with subsequent selection of responsive cell pools by fluorescence-activated cell sorting. Chimeric RNR (RNR hinge and ligand-binding domains fused to GAL4 DNA-binding domain) was stably transfected into mammalian Flp-In Chinese hamster ovary cells using Flp-mediated recombination into a single pre-integrated Flp recombination target site. Since no RNR ligand could be used as a control for monitoring the development of the RNR assay, we developed a parallel cell line with the functionally related well-characterized thyroid hormone nuclear receptor. This parallel thyroid hormone nuclear receptor system was used as a "guide" in optimizing the RNR assay for ultra-high-throughput screening in 3,456-well nanoplate format. The assay was successfully used to screen a large compound collection for RNR agonists. In this study we demonstrated the feasibility of developing and optimization of the high-throughput screening-compatible assay for the orphan nuclear receptor in the absence of its cognitive ligand.
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Affiliation(s)
- Marianna Kapitskaya
- Department of Ophthalmics Research, Merck Research Laboratories, West Point, PA 19486-0004, USA
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