1
|
Álvarez-Hernán G, de Mera-Rodríguez JA, Calle-Guisado V, Martín-Partido G, Rodríguez-León J, Francisco-Morcillo J. Retinal Development in a Precocial Bird Species, the Quail (Coturnix coturnix, Linnaeus 1758). Cells 2023; 12:cells12070989. [PMID: 37048062 PMCID: PMC10093483 DOI: 10.3390/cells12070989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 03/09/2023] [Accepted: 03/15/2023] [Indexed: 03/28/2023] Open
Abstract
The quail (Coturnix coturnix, Linnaeus 1758), a notable model used in developmental biology, is a precocial bird species in which the processes of retinal cell differentiation and retinal histogenesis have been poorly studied. The purpose of the present research is to examine the retinogenesis in this bird species immunohistochemically and compare the results with those from previous studies in precocial and altricial birds. We found that the first PCNA-negative nuclei are detected at Stage (St) 21 in the vitreal region of the neuroblastic layer, coinciding topographically with the first αTubAc-/Tuj1-/Isl1-immunoreactive differentiating ganglion cells. At St28, the first Prox1-immunoreactive nuclei can be distinguished in the vitreal side of the neuroblastic layer (NbL), but also the first visinin-immunoreactive photoreceptors in the scleral surface. The inner plexiform layer (IPL) emerges at St32, and the outer plexiform layer (OPL) becomes visible at St35—the stage in which the first GS-immunoreactive Müller cells are distinguishable. Newly hatched animals show a well-developed stratified retina in which the PCNA-and pHisH3-immunoreactivies are absent. Therefore, retinal cell differentiation in the quail progresses in the stereotyped order conserved among vertebrates, in which ganglion cells initially appear and are followed by amacrine cells, horizontal cells, and photoreceptors. Müller glia are one of the last cell types to be born. Plexiform layers emerge following a vitreal-to-scleral gradient. Finally, our results suggest that there are no significant differences in the timing of different events involved in retinal maturation between the quail and the chicken, but the same events are delayed in an altricial bird species.
Collapse
Affiliation(s)
- Guadalupe Álvarez-Hernán
- Área de Biología Celular, Departamento de Anatomía, Biología Celular y Zoología, Facultad de Ciencias, Universidad de Extremadura, 06006 Badajoz, Spain
| | - José Antonio de Mera-Rodríguez
- Área de Biología Celular, Departamento de Anatomía, Biología Celular y Zoología, Facultad de Ciencias, Universidad de Extremadura, 06006 Badajoz, Spain
| | - Violeta Calle-Guisado
- Área de Anatomía y Embriología Humana, Departamento de Anatomía, Biología Celular y Zoología, Facultad de Medicina, Universidad de Extremadura, 06006 Badajoz, Spain
| | - Gervasio Martín-Partido
- Área de Biología Celular, Departamento de Anatomía, Biología Celular y Zoología, Facultad de Ciencias, Universidad de Extremadura, 06006 Badajoz, Spain
| | - Joaquín Rodríguez-León
- Área de Anatomía y Embriología Humana, Departamento de Anatomía, Biología Celular y Zoología, Facultad de Medicina, Universidad de Extremadura, 06006 Badajoz, Spain
| | - Javier Francisco-Morcillo
- Área de Biología Celular, Departamento de Anatomía, Biología Celular y Zoología, Facultad de Ciencias, Universidad de Extremadura, 06006 Badajoz, Spain
- Correspondence:
| |
Collapse
|
2
|
Alvarez-Hernan G, de Mera-Rodríguez JA, Gañán Y, Solana-Fajardo J, Martín-Partido G, Rodríguez-León J, Francisco-Morcillo J. Development and postnatal neurogenesis in the retina: a comparison between altricial and precocial bird species. Neural Regen Res 2021; 16:16-20. [PMID: 32788442 PMCID: PMC7818864 DOI: 10.4103/1673-5374.286947] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The visual system is affected by neurodegenerative diseases caused by the degeneration of specific retinal neurons, the leading cause of irreversible blindness in humans. Throughout vertebrate phylogeny, the retina has two kinds of specialized niches of constitutive neurogenesis: the retinal progenitors located in the circumferential marginal zone and Müller glia. The proliferative activity in the retinal progenitors located in the circumferential marginal zone in precocial birds such as the chicken, the commonest bird model used in developmental and regenerative studies, is very low. This region adds only a few retinal cells to the peripheral edge of the retina during several months after hatching, but does not seem to be involved in retinal regeneration. Müller cells in the chicken retina are not proliferative under physiological conditions, but after acute damage some of them undergo a reprogramming event, dedifferentiating into retinal stem cells and generating new retinal neurons. Therefore, regenerative response after injury occurs with low efficiency in the precocial avian retina. In contrast, it has recently been shown that neurogenesis is intense in the retina of altricial birds at hatching. In particular, abundant proliferative activity is detected both in the circumferential marginal zone and in the outer half of the inner nuclear layer. Therefore, stem cell niches are very active in the retina of altricial birds. Although more extensive research is needed to assess the potential of proliferating cells in the adult retina of altricial birds, it emerges as an attractive model for studying different aspects of neurogenesis and neural regeneration in vertebrates.
Collapse
Affiliation(s)
- Guadalupe Alvarez-Hernan
- Área de Biología Celular, Departamento de Anatomía, Biología Celular y Zoología, Facultad de Ciencias, Universidad de Extremadura, Badajoz, Spain
| | - José Antonio de Mera-Rodríguez
- Área de Anatomía Humana, Departamento de Anatomía, Biología Celular y Zoología, Facultad de Medicina, Universidad de Extremadura, Badajoz, Spain
| | - Yolanda Gañán
- Área de Anatomía Humana, Departamento de Anatomía, Biología Celular y Zoología, Facultad de Medicina, Universidad de Extremadura, Badajoz, Spain
| | - Jorge Solana-Fajardo
- Servicio de Oftalmología, Complejo Hospitalario Universitario de Badajoz, Badajoz, Spain
| | - Gervasio Martín-Partido
- Área de Biología Celular, Departamento de Anatomía, Biología Celular y Zoología, Facultad de Ciencias, Universidad de Extremadura, Badajoz, Spain
| | - Joaquín Rodríguez-León
- Área de Anatomía Humana, Departamento de Anatomía, Biología Celular y Zoología, Facultad de Medicina, Universidad de Extremadura, Badajoz, Spain
| | - Javier Francisco-Morcillo
- Área de Biología Celular, Departamento de Anatomía, Biología Celular y Zoología, Facultad de Ciencias, Universidad de Extremadura, Badajoz, Spain
| |
Collapse
|
3
|
Toms D, Al-Ani A, Sunba S, Tong QYV, Workentine M, Ungrin M. Automated Hypothesis Generation to Identify Signals Relevant in the Development of Mammalian Cell and Tissue Bioprocesses, With Validation in a Retinal Culture System. Front Bioeng Biotechnol 2020; 8:534. [PMID: 32582664 PMCID: PMC7287043 DOI: 10.3389/fbioe.2020.00534] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 05/04/2020] [Indexed: 12/13/2022] Open
Abstract
We have developed an accessible software tool (receptoR) to predict potentially active signaling pathways in one or more cell type(s) of interest from publicly available transcriptome data. As proof-of-concept, we applied it to mouse photoreceptors, yielding the previously untested hypothesis that activin signaling pathways are active in these cells. Expression of the type 2 activin receptor (Acvr2a) was experimentally confirmed by both RT-qPCR and immunochemistry, and activation of this signaling pathway with recombinant activin A significantly enhanced the survival of magnetically sorted photoreceptors in culture. Taken together, we demonstrate that our approach can be easily used to mine publicly available transcriptome data and generate hypotheses around receptor expression that can be used to identify novel signaling pathways in specific cell types of interest. We anticipate that receptoR (available at https://www.ucalgary.ca/ungrinlab/receptoR) will enable more efficient use of limited research resources.
Collapse
Affiliation(s)
- Derek Toms
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada.,Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada
| | - Abdullah Al-Ani
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada.,Biomedical Engineering Graduate Program, University of Calgary, Calgary, AB, Canada.,Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada.,Leaders in Medicine Program, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Saud Sunba
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - Qing Yun Victor Tong
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - Matthew Workentine
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada
| | - Mark Ungrin
- Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada.,Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada.,Biomedical Engineering Graduate Program, University of Calgary, Calgary, AB, Canada.,Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
| |
Collapse
|
4
|
Álvarez-Hernán G, Hernández-Núñez I, Rico-Leo EM, Marzal A, de Mera-Rodríguez JA, Rodríguez-León J, Martín-Partido G, Francisco-Morcillo J. Retinal differentiation in an altricial bird species, Taeniopygia guttata: An immunohistochemical study. Exp Eye Res 2020; 190:107869. [DOI: 10.1016/j.exer.2019.107869] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 11/03/2019] [Accepted: 11/04/2019] [Indexed: 11/30/2022]
|
5
|
Akhtar T, Xie H, Khan MI, Zhao H, Bao J, Zhang M, Xue T. Accelerated photoreceptor differentiation of hiPSC-derived retinal organoids by contact co-culture with retinal pigment epithelium. Stem Cell Res 2019; 39:101491. [PMID: 31326746 DOI: 10.1016/j.scr.2019.101491] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 06/19/2019] [Accepted: 06/25/2019] [Indexed: 12/29/2022] Open
Abstract
Retinal organoids (ROs) derived from human-induced pluripotent stem cells recapitulate the three-dimensional structure of retina, mimic human retinal development, and provide cell sources for pre-clinical retinal transplantation. Retinal pigment epithelium (RPE) is crucial for normal outer retinal physiology, including phagocytosis of shed photoreceptor outer segments and secretion of neurotrophic and vasculotrophic growth factors. However, whether ROs-RPE co-culture can improve the differentiation of photoreceptors in ROs in vitro remains unknown. Herein, primary mouse RPE cells were contact co-cultured with ROs at different time points. Our results revealed that the RPE cells accelerated photoreceptor differentiation in ROs, as the cross talk between the RPE and ROs promoted the stage specific expression of photoreceptor markers at different differentiation stages. Thus, we established an improved co-culture system based on modeling of human retina-RPE dynamics during retinogenesis for the evaluation of ocular therapies.
Collapse
Affiliation(s)
- Tasneem Akhtar
- Eye Center, The First Affiliated Hospital of USTC, Hefei National Laboratory for Physical Sciences at the Microscale, Neurodegenerative Disorder Research Center, Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China
| | - Haohuan Xie
- Eye Center, The First Affiliated Hospital of USTC, Hefei National Laboratory for Physical Sciences at the Microscale, Neurodegenerative Disorder Research Center, Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China
| | - Muhammad Imran Khan
- Eye Center, The First Affiliated Hospital of USTC, Hefei National Laboratory for Physical Sciences at the Microscale, Neurodegenerative Disorder Research Center, Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China
| | - Huan Zhao
- Department of Biological and Environmental Engineering, Hefei University, Hefei 230601, China
| | - Jin Bao
- Eye Center, The First Affiliated Hospital of USTC, Hefei National Laboratory for Physical Sciences at the Microscale, Neurodegenerative Disorder Research Center, Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China
| | - Mei Zhang
- Eye Center, The First Affiliated Hospital of USTC, Hefei National Laboratory for Physical Sciences at the Microscale, Neurodegenerative Disorder Research Center, Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China.
| | - Tian Xue
- Eye Center, The First Affiliated Hospital of USTC, Hefei National Laboratory for Physical Sciences at the Microscale, Neurodegenerative Disorder Research Center, Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China; Chinese Academy of Sciences Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China; Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing 100101, China.
| |
Collapse
|
6
|
Abstract
Purpose Retinal degenerative diseases lead to the death of retinal neurons causing visual impairment and blindness. In lower order vertebrates, the retina and its surrounding tissue contain stem cell niches capable of regenerating damaged tissue. Here we examine these niches and review their capacity to be used as retinal stem/progenitor cells (RSC/RPCs) for retinal repair. Recent Findings Exogenous factors can control the in vitro activation of RSCs/PCs found in several niches within the adult eye including cells in the ciliary margin, the retinal pigment epithelium, iris pigment epithelium as well as the inducement of Müller and amacrine cells within the neural retina itself. Recently, factors have been identified for the activation of adult mammalian Müller cells to a RPC state in vivo. Summary Whereas cell transplantation still holds potential for retinal repair, activation of the dormant native regeneration process may lead to a more successful process including greater integration efficiency and proper synaptic targeting.
Collapse
|
7
|
Enright JM, Lawrence KA, Hadzic T, Corbo JC. Transcriptome profiling of developing photoreceptor subtypes reveals candidate genes involved in avian photoreceptor diversification. J Comp Neurol 2014; 523:649-68. [PMID: 25349106 DOI: 10.1002/cne.23702] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Revised: 10/21/2014] [Accepted: 10/22/2014] [Indexed: 12/26/2022]
Abstract
Avian photoreceptors are a diverse class of neurons, comprised of four single cones, the two members of the double cone, and rods. The signaling events and transcriptional regulators driving the differentiation of these diverse photoreceptors are largely unknown. In addition, many distinctive features of photoreceptor subtypes, including spectral tuning, oil droplet size and pigmentation, synaptic targets, and spatial patterning, have been well characterized, but the molecular mechanisms underlying these attributes have not been explored. To identify genes specifically expressed in distinct chicken (Gallus gallus) photoreceptor subtypes, we developed fluorescent reporters that label photoreceptor subpopulations, isolated these subpopulations by using fluorescence-activated cell sorting, and subjected them to next-generation sequencing. By comparing the expression profiles of photoreceptors labeled with rhodopsin, red opsin, green opsin, and violet opsin reporters, we have identified hundreds of differentially expressed genes that may underlie the distinctive features of these photoreceptor subtypes. These genes are involved in a variety of processes, including phototransduction, transcriptional regulation, cell adhesion, maintenance of intra- and extracellular structure, and metabolism. Of particular note are a variety of differentially expressed transcription factors, which may drive and maintain photoreceptor diversity, and cell adhesion molecules, which may mediate spatial patterning of photoreceptors and act to establish retinal circuitry. These analyses provide a framework for future studies that will dissect the role of these various factors in the differentiation of avian photoreceptor subtypes.
Collapse
Affiliation(s)
- Jennifer M Enright
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri, 63110-1024
| | | | | | | |
Collapse
|
8
|
Venters SJ, Mikawa T, Hyer J. Early divergence of central and peripheral neural retina precursors during vertebrate eye development. Dev Dyn 2014; 244:266-76. [PMID: 25329498 DOI: 10.1002/dvdy.24218] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 10/07/2014] [Accepted: 10/12/2014] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND During development of the vertebrate eye, optic tissue is progressively compartmentalized into functionally distinct tissues. From the central to the peripheral optic cup, the original optic neuroepithelial tissue compartmentalizes, forming retina, ciliary body, and iris. The retina can be further sub-divided into peripheral and central compartments, where the central domain is specialized for higher visual acuity, having a higher ratio and density of cone photoreceptors in most species. RESULTS Classically, models depict a segregation of the early optic cup into only two domains, neural and non-neural. Recent studies, however, uncovered discrete precursors for central and peripheral retina in the optic vesicle, indicating that the neural retina cannot be considered as a single unit with homogeneous specification and development. Instead, central and peripheral retina may be subject to distinct developmental pathways that underlie their specialization. CONCLUSIONS This review focuses on lineage relationships in the retina and revisits the historical context for segregation of central and peripheral retina precursors before overt eye morphogenesis.
Collapse
Affiliation(s)
- Sara J Venters
- Cardiovascular Research Institute, University of California, San Francisco, California; Department of Neurosurgery, University of California, San Francisco San Francisco, California
| | | | | |
Collapse
|
9
|
A high content screening approach to identify molecules neuroprotective for photoreceptor cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 801:773-81. [PMID: 24664770 DOI: 10.1007/978-1-4614-3209-8_97] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
PURPOSE Retinal degenerations are a heterogeneous group of diseases in which there is slow but progressive loss of photoreceptors (PR). There are currently no approved therapies for treating retinal degenerations. In an effort to identify novel small molecules that are (1) neuroprotective and (2) promote PR differentiation, we have developed microscale (1,536 well) cell culture assays using primary retinal neurons. METHODS Primary murine retinal cells are isolated, seeded, treated with a 1,280 compound chemical library in a 7 point titration and then cultured under conditions developed to assay protection against an introduced stress or enhance PR differentiation. In the protection assays a chemical insult is introduced and viability assessed after 72 h using CellTiterGlo, a single-step chemiluminescent reagent. In the differentiation assay, cells are isolated from the rhodopsin-GFP knock-in mouse and PR differentiation is assessed by fixing cells after 21 days in culture and imaging with the Acumen plate-based laser cytometer (TTP Labtech) to determine number and intensity of GFP-expressing cells. Positive wells are re-imaged at higher resolution with an INCell2000 automated microscope (GE). Concentration-response curves are generated to pharmacologically profile each compound and hits identified by xx. RESULTS We have developed PR differentiation and neuroprotection assays with a signal to background (S/B) ratios of 11 and 3, and a coefficient of variation (CV) of 20 and 9 %, suitable for chemical screening. Staurosporine has been shown in our differentiation assay to simultaneously increase the number of rhodopsin positive objects while decreasing the mean rhodopsin intensity and punctate rhodopsin fluorescent objects. CONCLUSIONS Using primary murine retinal cells, we developed high throughput assays to identify small molecules that influence PR development and survival. By screening multiple compound concentrations, dose-response curves can be generated, and the false negative rate minimized. It is hoped that this work will identify both potential preclinical candidates as well as molecular probes that will be useful for analysis of the molecular mechanisms that promote PR differentiation and survival.
Collapse
|
10
|
The maturation of photoreceptors in the avian retina is stimulated by thyroid hormone. Neuroscience 2011; 178:250-60. [PMID: 21256198 DOI: 10.1016/j.neuroscience.2011.01.022] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Revised: 01/11/2011] [Accepted: 01/12/2011] [Indexed: 11/22/2022]
Abstract
During retinal development, the cell-fate of photoreceptors is committed long before maturation, which entails the expression of opsins and functional transduction of light. The mechanisms that delay the maturation of photoreceptors remain unknown. We have recently reported that immature photoreceptors express the LIM domain transcription factors Islet2 and Lim3, as well as the cell-surface glycoprotein axonin1 [Fischer et al., (2008a) J Comp Neurol 506:584-603]. As the photoreceptors mature to form outer segments and express photopigments, the expression of the Islet2, Lim3 and axonin1 is diminished. The purpose of this study was to investigate whether thyroid hormone (TH) influences the maturation of photoreceptors. We studied the maturation of photoreceptors across the gradient of maturity that exists in far peripheral regions of the post-natal chicken retina [Ghai et al., (2008) Brain Res 1192:76-89]. We found that intraocular injections of TH down-regulated Islet2, Lim3 and axonin1 in photoreceptors in far peripheral regions of the retina. By contrast, TH stimulated the up-regulation of red-green opsin, violet opsin, rhodopsin and calbindin in photoreceptors. We found a correlation between the onset of RLIM (RING finger LIM-domain binding protein) and down-regulation of Islet2 and Lim3 in maturing photoreceptors; RLIM is known to interfere with the transcriptional activity of LIM-domain transcription factors. We conclude that TH stimulates the maturation of photoreceptors in the avian retina. We propose that TH inhibits the expression of Islet2 and Lim3, which thereby permits photoreceptor maturation and the onset of photopigment-expression.
Collapse
|
11
|
Socodato R, Brito R, Calaza KC, Paes-de-Carvalho R. Developmental regulation of neuronal survival by adenosine in the in vitro and in vivo avian retina depends on a shift of signaling pathways leading to CREB phosphorylation or dephosphorylation. J Neurochem 2010; 116:227-39. [PMID: 21054391 DOI: 10.1111/j.1471-4159.2010.07096.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Previous studies have shown a cAMP/protein kinase A-dependent neuroprotective effect of adenosine on glutamate or re-feeding-induced apoptosis in chick retina neuronal cultures. In the present work, we have studied the effect of adenosine on the survival of retinal progenitor cells. Cultures obtained from 6-day-old (E6) or from 8-day-old (E8) chick embryos were challenged 2 h (C0) or 1 day (C1) after seeding and analyzed after 3-4 days in vitro. Surprisingly, treatment with the selective A2a adenosine receptor agonists N(6) -[2-(3,5-dimethoxyphenyl)-2-(2-methylphenyl)-ethyl]adenosine (DPMA) or 3-[4-[2-[[6-amino-9-[(2R,3R,4S,5S)-5-(ethylcarbamoyl)-3,4-dihydroxy-oxolan-2-yl]purin-2-yl]amino]ethyl]phenyl]propanoic acid (CGS21680) promoted cell death when added at E6C0 but not at E6C1 or E8C0. DPMA-induced cell death involved activation of A2a receptors and the phospholipase C/protein kinase C but not the cAMP/protein kinase A pathway, and was not correlated with early modulation of precursor cells proliferation. Regarding cyclic nucleotide responsive element binding protein (CREB) phosphorylation, cultures from E6 embryos behave in an opposite manner from that from E8 embryos, both in vitro and in vivo. While the phospho-CREB level was high at E6C0 cultures and could be diminished by DPMA, it was lower at E8C0 and could be increased by DPMA. Similar to what was observed in cell survival studies, CREB dephosphorylation induced by DPMA in E6C0 cultures was dependent on the Phospholipase C/protein kinase C pathway. Accordingly, cell death induced by DPMA was inhibited by okadaic acid, a phosphatase blocker. Moreover, DPMA as well as the adenosine uptake blocker nitrobenzyl mercaptopurine riboside (NBMPR) modulate cell survival and CREB phosphorylation in a population of cells in the ganglion cell layer in vivo. These data suggest that A2a adenosine receptors as well as CREB may display a novel and important function by controlling the repertoire of developing retinal neurons.
Collapse
Affiliation(s)
- Renato Socodato
- Laboratories of Cellular Neurobiology and Neurobiology of Retina, Program of Neurosciences, Institute of Biology, Fluminense Federal University, Niterói, RJ, Brazil
| | | | | | | |
Collapse
|
12
|
Roger JE, Nellissery J, Kim DS, Swaroop A. Sumoylation of bZIP transcription factor NRL modulates target gene expression during photoreceptor differentiation. J Biol Chem 2010; 285:25637-44. [PMID: 20551322 DOI: 10.1074/jbc.m110.142810] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Development of rod photoreceptors in the mammalian retina is critically dependent on the basic motif-leucine zipper transcription factor NRL (neural retina leucine zipper). In the absence of NRL, photoreceptor precursors in mouse retina produce only cones that primarily express S-opsin. Conversely, ectopic expression of NRL in post-mitotic precursors leads to a rod-only retina. To explore the role of signaling molecules in modulating NRL function, we identified putative sites of post-translational modification in the NRL protein by in silico analysis. Here, we demonstrate the sumoylation of NRL in vivo and in vitro, with two small ubiquitin-like modifier (SUMO) molecules attached to the Lys-20 residue. NRL-K20R and NRL-K20R/K24R sumoylation mutants show reduced transcriptional activation of Nr2e3 and rhodopsin promoters (two direct targets of NRL) in reporter assays when compared with wild-type NRL. Consistent with this, in vivo electroporation of the NRL-K20R/K24R mutant into newborn Nrl(-/-) mouse retina leads to reduced Nr2e3 activation and only a partial rescue of the Nrl(-/-) phenotype in contrast to the wild-type NRL that is able to convert cones to rod photoreceptors. Although PIAS3 (protein inhibitor of activated STAT3), an E3-SUMO ligase implicated in photoreceptor differentiation, can be immunoprecipitated with NRL, there appears to be redundancy in E3 ligases, and PIAS3 does not seem to be essential for NRL sumoylation. Our studies suggest an important role of sumoylation in fine-tuning the activity of NRL and thereby incorporating yet another layer of control in gene regulatory networks involved in photoreceptor development and homeostasis.
Collapse
Affiliation(s)
- Jerome E Roger
- Neurobiology-Neurodegeneration and Repair Laboratory, NEI, National Institutes of Health, Bethesda, Maryland 20892, USA
| | | | | | | |
Collapse
|
13
|
Miki A, Miki K, Ueno S, Wersinger DMB, Berlinicke C, Shaw GC, Usui S, Wang Y, Zack DJ, Campochiaro PA. Prolonged blockade of VEGF receptors does not damage retinal photoreceptors or ganglion cells. J Cell Physiol 2010; 224:262-72. [PMID: 20232317 DOI: 10.1002/jcp.22129] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
It has recently been reported that relatively short-term inhibition of vascular endothelial growth factor (VEGF) signaling can cause photoreceptor cell death, a potentially clinically important finding since VEGF blockade has become an important modality of treatment of ocular neovascularization and macular edema. However, in a set of studies in which we achieved extended and complete blockage of VEGF-induced vascular leakage through retinal expression of a VEGF binding protein, we did not observe any toxicity to retinal neurons. To follow-up on these apparently discrepant findings, we designed a set of experiments with the kinase inhibitor SU4312, which blocks phosphorylation of VEGF receptors, to look directly for evidence of VEGF inhibition-related retinal toxicity. Using transgenic mice with sustained expression of VEGF in photoreceptors, we determined that periocular injection of 3 microg of SU4312 every 5 days markedly suppressed subretinal neovascularization, indicating effective blockade of VEGF signaling. Wild-type mice given periocular injections of 5 microg of SU4312 every 5 days for up to 12 weeks showed normal scotopic and photopic electroretinograms (ERGs), no TUNEL stained cells in the retina, and no reduction in outer nuclear layer thickness. Incubation of cultured ganglion cells or retinal cultures containing photoreceptors with high doses of SU4312 did not reduce cell viability. These data suggest that blocking VEGF signaling in the retina for up to 12 weeks does not damage photoreceptors nor alter ERG function and should reassure patients who are receiving frequent injections of VEGF antagonists for choroidal and retinal vascular diseases.
Collapse
Affiliation(s)
- Akiko Miki
- Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287-9277, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Voisin P, Bernard M. Cyclic AMP-dependent activation of rhodopsin gene transcription in cultured retinal precursor cells of chicken embryo. J Neurochem 2009; 110:318-27. [PMID: 19457115 DOI: 10.1111/j.1471-4159.2009.06136.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The present study describes a robust 50-fold increase in rhodopsin gene transcription by cAMP in cultured retinal precursor cells of chicken embryo. Retinal cells isolated at embryonic day 8 (E8) and cultured for 3 days in serum-supplemented medium differentiated mostly into red-sensitive cones and to a lesser degree into green-sensitive cones, as indicated by real-time RT-PCR quantification of each specific opsin mRNA. In contrast, both rhodopsin mRNA concentration and rhodopsin gene promoter activity required the presence of cAMP-increasing agents [forskolin and 3-isobutyl-1-methylxanthine (IBMX)] to reach significant levels. This response was rod-specific and was sufficient to activate rhodopsin gene transcription in serum-free medium. The increase in rhodopsin mRNA levels evoked by a series of cAMP analogs suggested the response was mediated by protein kinase A, not by EPAC. Membrane depolarization by high KCl concentration also increased rhodopsin mRNA levels and this response was strongly potentiated by IBMX. The rhodopsin gene response to cAMP-increasing agents was developmentally gated between E6 and E7. Rod-specific transducin alpha subunit mRNA levels also increased up to 50-fold in response to forskolin and IBMX, while rod-specific phosphodiesterase-VI and rod arrestin transcripts increased 3- to 10-fold. These results suggest a cAMP-mediated signaling pathway may play a role in rod differentiation.
Collapse
Affiliation(s)
- Pierre Voisin
- Institut de Physiologie et Biologie Cellulaires, Université de Poitiers, CNRS, Poitiers, France.
| | | |
Collapse
|
15
|
West E, Pearson R, MacLaren R, Sowden J, Ali R. Cell transplantation strategies for retinal repair. PROGRESS IN BRAIN RESEARCH 2009; 175:3-21. [PMID: 19660645 PMCID: PMC3272389 DOI: 10.1016/s0079-6123(09)17501-5] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Cell transplantation is a novel therapeutic strategy to restore visual responses to the degenerate adult neural retina and represents an exciting area of regenerative neurotherapy. So far, it has been shown that transplanted postmitotic photoreceptor precursors are able to functionally integrate into the adult mouse neural retina. In this review, we discuss the differentiation of photoreceptor cells from both adult and embryonic-derived stem cells and their potential for retinal cell transplantation. We also discuss the strategies used to overcome barriers present in the degenerate neural retina and improve retinal cell integration. Finally, we consider the future translation of retinal cell therapy as a therapeutic strategy to treat retinal degeneration.
Collapse
Affiliation(s)
- E.L. West
- Department of Genetics, UCL Institute of Ophthalmology, London, UK
| | - R.A. Pearson
- Department of Genetics, UCL Institute of Ophthalmology, London, UK
| | - R.E. MacLaren
- Department of Genetics, UCL Institute of Ophthalmology, London, UK
- Vitreoretinal Service, Moorfields Eye Hospital, London, UK
| | - J.C. Sowden
- Developmental Biology Unit, UCL Institute of Child Health, London, UK
| | - R.R. Ali
- Department of Genetics, UCL Institute of Ophthalmology, London, UK
- Molecular Immunology Unit, UCL Institute of Child Health, London, UK
| |
Collapse
|
16
|
Abstract
Retinal degeneration culminating in photoreceptor loss is the leading cause of untreatable blindness in the developed world. In this review, we consider how photoreceptors might be replaced by transplantation and how stem cells might be optimised for use as donor cells in future clinical strategies for retinal repair. We discuss the current advances in human and animal models of retinal cell transplantation, focussing on stem cell and reproductive cloning biology, in relation to the practical issues of retinal transplantation surgery. Stem and progenitor cells can be isolated from a number of sources including embryonic tissue, adult brain and even the retina, prompting many researchers to investigate the potential for using these cells to generate photoreceptors for transplantation. Nevertheless, several obstacles need to be overcome before these techniques can be applied in a clinical setting. Embryonic or stem cells have so far shown little ability to differentiate into retinal phenotypes when transplanted into the adult retina. We have recently noted, however, that donor cells harvested much later, at the photoreceptor precursor developmental stage, can be transplanted successfully and restore visual function. The current challenge is to understand the developmental processes that guide embryonic or adult stem cells towards photoreceptor differentiation, so that large numbers of these cells might be transplanted at the optimal stage. Future advances in reproductive cloning technology could lead to the successful generation of stem cells from adult somatic cells, thereby facilitating auto-transplantation of genetically identical cells in patients requiring photoreceptor replacement.
Collapse
Affiliation(s)
- R E MacLaren
- Vitreoretinal Service, Moorfields Eye Hospital, London, UK.
| | | |
Collapse
|
17
|
Fischer AJ, Foster S, Scott MA, Sherwood P. Transient expression of LIM-domain transcription factors is coincident with delayed maturation of photoreceptors in the chicken retina. J Comp Neurol 2008; 506:584-603. [PMID: 18072193 DOI: 10.1002/cne.21578] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
In the retina of warm-blooded vertebrates, photoreceptors are specified many days before the onset of synaptogenesis and the expression of photopigments. The factors that regulate the maturation of photoreceptors in the developing retina remain unknown. We report here that photoreceptors transiently express LIM-domain transcription factors during the development of the chicken retina. We examined the differentiation of photoreceptors through the normal course of embryonic development and at the far periphery of the postnatal retina, where the differentiation of photoreceptors is slowed and persists across a spatial gradient. In the embryonic retina, we find visinin-positive photoreceptors that transiently express Islet2 and Lim3 starting at E8 and ending around E15, but persisting in far peripheral regions of the retina through the first 2 weeks of postnatal development. During early stages of photoreceptor maturation, there is coincident and transient expression of the LIM-domain factors with axonin1, a cell surface glycoprotein that is a member of the immunoglobulin superfamily. Coincident with the downregulation of Islet2 and Lim3, we find the upregulation of calbindin, red/green opsin, rhodopsin, and a synaptic marker in the outer plexiform layer (OPL; dystrophin). In the periphery of the postnatal retina, photoreceptors that express Islet2, Lim3, and axonin1 do not overlap with photoreceptors that express calbindin, red/green opsin, rhodopsin, and dystrophin. We propose that Islet2 and Lim3 may promote the expression of genes that are involved in the early stages of differentiation but may suppress the expression of genes that are required in the mature photoreceptors.
Collapse
Affiliation(s)
- Andy J Fischer
- Department of Neuroscience, The Ohio State University, Columbus, Ohio 43210, USA.
| | | | | | | |
Collapse
|
18
|
Adler R. Curing blindness with stem cells: hope, reality, and challenges. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 613:3-20. [PMID: 18188924 DOI: 10.1007/978-0-387-74904-4_1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Ruben Adler
- Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
| |
Collapse
|
19
|
MacNeil A, Pearson RA, MacLaren RE, Smith AJ, Sowden JC, Ali RR. Comparative Analysis of Progenitor Cells Isolated from the Iris, Pars Plana, and Ciliary Body of the Adult Porcine Eye. Stem Cells 2007; 25:2430-8. [PMID: 17600111 DOI: 10.1634/stemcells.2007-0035] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Photoreceptor loss causes irreversible blindness in many retinal diseases. The identification of suitable donor cell populations is of considerable interest because of their potential use to replace the photoreceptors lost in disease. Stem or progenitor cells that give rise to neurons and glia have been identified in several regions of the brain, including the embryonic retina and the ciliary epithelium of the adult eye, raising the possibility of autologous transplantation. However, there has been little systematic investigation into precisely which regions of the large mammalian adult eye give rise to such cells. Here, we show for the first time using the porcine eye the presence of progenitor cells in additional regions of the adult eye, including the pars plana and iris, regions that, in the human, are readily accessible during routine eye surgery. When cultured in the presence of growth factors, these cells proliferate to form neurospheres comprised of cells expressing retinal progenitor markers. Using an adherent monolayer culture system, these cells could be readily expanded to increase their number more than 1 million-fold and maintain a progenitor phenotype. When grown on the substrate laminin in the presence of serum, cells derived from both spheres and monolayer cultures differentiated into neurons and glia. These results suggest that a population of cells derived from the adult iris, pars plana, and ciliary body of a large mammalian species, the pig, has progenitor properties and neurogenic potential, thereby providing novel sources of donor cells for transplantation studies. Disclosure of potential conflicts of interest is found at the end of this article.
Collapse
Affiliation(s)
- Angus MacNeil
- Division of Molecular Therapy, Institute of Ophthalmology, University College London, 11-43 Bath Street, London, EC1V 9EL UK
| | | | | | | | | | | |
Collapse
|
20
|
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.
Collapse
Affiliation(s)
| | - Pamela A. Raymond
- Department of Molecular, Cellular and Developmental Biology, University of Michigan
| |
Collapse
|
21
|
Nelson BR, Hartman BH, Georgi SA, Lan MS, Reh TA. Transient inactivation of Notch signaling synchronizes differentiation of neural progenitor cells. Dev Biol 2007; 304:479-98. [PMID: 17280659 PMCID: PMC1979095 DOI: 10.1016/j.ydbio.2007.01.001] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2006] [Revised: 12/23/2006] [Accepted: 01/02/2007] [Indexed: 11/19/2022]
Abstract
In the developing nervous system, the balance between proliferation and differentiation is critical to generate the appropriate numbers and types of neurons and glia. Notch signaling maintains the progenitor pool throughout this process. While many components of the Notch pathway have been identified, the downstream molecular events leading to neural differentiation are not well understood. We have taken advantage of a small molecule inhibitor, DAPT, to block Notch activity in retinal progenitor cells, and analyzed the resulting molecular and cellular changes over time. DAPT treatment causes a massive, coordinated differentiation of progenitors that produces cell types appropriate for their developmental stage. Transient exposure of retina to DAPT for specific time periods allowed us to define the period of Notch inactivation that is required for a permanent commitment to differentiate. Inactivation of Notch signaling revealed a cascade of proneural bHLH transcription factor gene expression that correlates with stages in progenitor cell differentiation. Microarray/QPCR analysis confirms the changes in Notch signaling components, and reveals new molecular targets for investigating neuronal differentiation. Thus, transient inactivation of Notch signaling synchronizes progenitor cell differentiation, and allows for a systematic analysis of key steps in this process.
Collapse
Affiliation(s)
- Branden R. Nelson
- Department of Biological Structure, University of Washington, Seattle, WA 98195
| | - Byron H. Hartman
- Department of Biological Structure, University of Washington, Seattle, WA 98195
| | - Sean A. Georgi
- Neurobiology and Behavior Program, University of Washington, Seattle, WA 98195
| | - Michael S. Lan
- The Research Institute for Children, Children's Hospital, New Orleans, LA 70118
| | - Thomas A. Reh
- Department of Biological Structure, University of Washington, Seattle, WA 98195
- Neurobiology and Behavior Program, University of Washington, Seattle, WA 98195
- Author for correspondence: Dr. T.A. Reh, Department of Biological Structure, Box 357420, University of Washington, Seattle, WA 98195, , phone 206-543-8043, fax 206-543-1524
| |
Collapse
|
22
|
Abstract
The retinas of teleost fish have long been of interest to developmental neurobiologists for their persistent plasticity during growth, life history changes, and response to injury. Because the vertebrate retina is a highly conserved tissue, the study of persistent plasticity in teleosts has provided insights into mechanisms for postembryonic retinal neurogenesis in mammals. In addition, in the past 10 years there has been an explosion in the use of teleost fish-zebrafish (Danio rerio) in particular-to understand the mechanisms of embryonic retinal neurogenesis in a model vertebrate with genetic resources. This review summarizes the key features of teleost retinal neurogenesis that make it a productive and interesting experimental system, and focuses on the contributions to our knowledge of retinal neurogenesis that uniquely required or significantly benefited from the use of a fish model system.
Collapse
Affiliation(s)
- Deborah L Stenkamp
- Department of Biological Sciences, University of Idaho, Moscow, Idaho 83844, USA
| |
Collapse
|
23
|
Contin MA, Verra DM, Guido ME. An invertebrate‐like phototransduction cascade mediates light detection in the chicken retinal ganglion cells. FASEB J 2006; 20:2648-50. [PMID: 17077288 DOI: 10.1096/fj.06-6133fje] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Prebilaterian animals perceived ambient light through nonvisual rhabdomeric photoreceptors (RPs), which evolved as support of the chordate visual system. In vertebrates, the identity of nonvisual photoreceptors and the phototransduction cascade involved in nonimage forming tasks remain uncertain. We investigated whether chicken retinal ganglion cells (RGCs) could be nonvisual photoreceptors and the nature of the photocascade involved. We found that primary cultures of chicken embryonic RGCs express such RP markers as transcription factors Pax6 and Brn3, photopigment melanopsin, and G-protein q but not markers for ciliary photoreceptors (alpha-transducin and Crx). To investigate the photoreceptive capability of RGCs, we assessed the direct effect of light on 3H-melatonin synthesis in RGC cultures synchronized to 12:12 h light-dark cycles. In constant dark, RGCs displayed a daily variation in 3H-melatonin levels peaking at subjective day, which was significantly inhibited by light. This light effect was further increased by the chromophore all-trans-retinal and suppressed by specific inhibitors of the invertebrate photocascade involving phosphoinositide hydrolysis (100 microM neomycin; 5 microM U73122) and Ca2+ mobilization (10 mM BAPTA; 1 mM lanthanum). The results demonstrate that chicken RGCs are intrinsically photosensitive RPs operating via an invertebrate-like phototransduction cascade, which may be responsible for early detection of light before vision occurs.
Collapse
Affiliation(s)
- Maria Ana Contin
- CIQUIBIC- Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, 5000 Córdoba, Argentina
| | | | | |
Collapse
|
24
|
Liu Q, Frey RA, Babb-Clendenon SG, Liu B, Francl J, Wilson AL, Marrs JA, Stenkamp DL. Differential expression of photoreceptor-specific genes in the retina of a zebrafish cadherin2 mutant glass onion and zebrafish cadherin4 morphants. Exp Eye Res 2006; 84:163-75. [PMID: 17070801 PMCID: PMC1853368 DOI: 10.1016/j.exer.2006.09.011] [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: 07/21/2006] [Revised: 09/13/2006] [Accepted: 09/17/2006] [Indexed: 10/24/2022]
Abstract
Cadherins are Ca2+ -dependent transmembrane molecules that mediate cell-cell adhesion through homophilic interactions. Cadherin2 (also called N-cadherin) and cadherin4 (also called R-cadherin), members of the classic cadherin subfamily, have been shown to be involved in development of a variety of tissues and organs including the visual system. To gain insight into cadherin2 and cadherin4 function in differentiation of zebrafish photoreceptors, we have analyzed expression patterns of several photoreceptor-specific genes (crx, gnat1, gnat2, irbp, otx5, rod opsin, rx1, and uv opsin) and/or a cone photoreceptor marker (zpr-1) in the retina of a zebrafish cadherin2 mutant, glass onion (glo) and in zebrafish embryos injected with a cadherin4 specific antisense morpholino oligonucleotide (cdh4MO). We find that expression of all these genes, and of zpr-1, is greatly reduced in the retina of both the glo and cadherin4 morphants. Moreover, in these embryos, expression of some genes (e.g. gnat1, gnat2 and irbp) is more affected than others (e.g. rod opsin and uv opsin). In embryos with both cadherins functions blocked (glo embryos injected with the cdh4MO), the eye initially formed, but became severely and progressively disintegrated and expressed little or no crx and otx5 as development proceeded. Our results suggest that cadherin2 and cadherin4 play important roles in the differentiation of zebrafish retinal photoreceptors.
Collapse
Affiliation(s)
- Q Liu
- Department of Biology, University of Akron, 302 Buchtel Common, Akron, OH 44325, USA.
| | | | | | | | | | | | | | | |
Collapse
|
25
|
Moreira EF, Adler R. Effects of follistatin overexpression on cell differentiation in the chick embryo retina. Dev Biol 2006; 298:272-84. [PMID: 16872597 DOI: 10.1016/j.ydbio.2006.06.035] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2006] [Revised: 06/21/2006] [Accepted: 06/22/2006] [Indexed: 11/19/2022]
Abstract
Although activin is expressed in the embryonic central nervous system (CNS), its possible functions in the regulation of CNS neuronal differentiation remain largely unknown. We have investigated this question in the retina, a well-characterized CNS structure previously shown to respond to activin in vitro, and to express activin subunits and receptors in vivo. RCAS retroviruses were used to overexpress in the chick retina in ovo either follistatin (FS), an activin-binding protein and inhibitor, or alkaline phosphatase (AP), as control. FS-treated retinas appeared normal until ED 8, when they showed a reduction of the inner plexiform layer, accompanied by a marked decrease in the frequency of amacrine cells. The territory lacking amacrine cells showed downregulation of transcription factors necessary for amacrine cell differentiation, such as Pax6 and AP2alpha, accompanied by ectopic expression of transcription factors associated with the development of horizontal or bipolar neurons, such as Prox1, Chx10 and NeuroM. Increases in cell death were also observed in FS-treated retinas. Taken together with previous in vitro studies, our results suggest that activin is a powerful regulator of neuronal differentiation in the central nervous system.
Collapse
Affiliation(s)
- Ernesto F Moreira
- Department of Opthalmology, The Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21287-9257, USA
| | | |
Collapse
|
26
|
Abstract
Progress in the study of the molecular mechanisms that regulate neuronal differentiation has been quite impressive in recent years, and promises to continue to an equally fast pace. This should not lead us into a sense of complacency, however, because there are still significant barriers that cannot be overcome by simply conducting the same type of experiments that we have been performing thus far. This article will describe some of these challenges, while highlighting the conceptual and methodological breakthroughs that will be necessary to overcome them.
Collapse
Affiliation(s)
- Ruben Adler
- Department of Ophthalmology and Neuroscience The Johns Hopkins University School of Medicine Baltimore, MD 21287-9257, USA.
| |
Collapse
|