101
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Kim HT, Kim JW. Compartmentalization of vertebrate optic neuroephithelium: external cues and transcription factors. Mol Cells 2012; 33:317-24. [PMID: 22450691 PMCID: PMC3887801 DOI: 10.1007/s10059-012-0030-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Revised: 02/21/2012] [Accepted: 02/24/2012] [Indexed: 02/02/2023] Open
Abstract
The vertebrate eye is a laterally extended structure of the forebrain. It develops through a series of events, including specification and regionalization of the anterior neural plate, evagination of the optic vesicle (OV), and development of three distinct optic structures: the neural retina (NR), optic stalk (OS), and retinal pigment epithelium (RPE). Various external signals that act on the optic neuroepithelium in a spatial- and temporal-specific manner control the fates of OV subdomains by inducing localized expression of key transcription factors. Investigating the mechanisms underlying compartmentalization of these distinct optic neuroepithelium-derived tissues is therefore not only important from the standpoint of accounting for vertebrate eye morphogenesis, it is also helpful for understanding the fundamental basis of fate determination of other neuroectoderm- derived tissues. This review focuses on the molecular signatures of OV subdomains and the external factors that direct the development of tissues originating from the OV.
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Affiliation(s)
- Hyoung-Tai Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701,
Korea
| | - Jin Woo Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701,
Korea
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102
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Thanos A, Morizane Y, Murakami Y, Giani A, Mantopoulos D, Kayama M, Roh MI, Michaud N, Pawlyk B, Sandberg M, Young LH, Miller JW, Vavvas DG. Evidence for baseline retinal pigment epithelium pathology in the Trp1-Cre mouse. THE AMERICAN JOURNAL OF PATHOLOGY 2012; 180:1917-27. [PMID: 22429967 DOI: 10.1016/j.ajpath.2012.01.017] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2011] [Revised: 12/28/2011] [Accepted: 01/20/2012] [Indexed: 01/14/2023]
Abstract
The increasing popularity of the Cre/loxP recombination system has led to the generation of numerous transgenic mouse lines in which Cre recombinase is expressed under the control of organ- or cell-specific promoters. Alterations in retinal pigment epithelium (RPE), a multifunctional cell monolayer that separates the retinal photoreceptors from the choroid, are prevalent in the pathogenesis of a number of ocular disorders, including age-related macular degeneration. To date, six transgenic mouse lines have been developed that target Cre to the RPE under the control of various gene promoters. However, multiple lines of evidence indicate that high levels of Cre expression can be toxic to mammalian cells. In this study, we report that in the Trp1-Cre mouse, a commonly used transgenic Cre strain for RPE gene function studies, Cre recombinase expression alone leads to RPE dysfunction and concomitant disorganization of RPE layer morphology, large areas of RPE atrophy, retinal photoreceptor dysfunction, and microglial cell activation in the affected areas. The phenotype described herein is similar to previously published reports of conditional gene knockouts that used the Trp1-Cre mouse, suggesting that Cre toxicity alone could account for some of the reported phenotypes and highlighting the importance of the inclusion of Cre-expressing mice as controls in conditional gene targeting studies.
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Affiliation(s)
- Aristomenis Thanos
- Retina Service, Angiogenesis Laboratory, Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts 02114, USA
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103
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Eiraku M, Adachi T, Sasai Y. Relaxation-expansion model for self-driven retinal morphogenesis: a hypothesis from the perspective of biosystems dynamics at the multi-cellular level. Bioessays 2012; 34:17-25. [PMID: 22052700 PMCID: PMC3266490 DOI: 10.1002/bies.201100070] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The generation of complex organ structures such as the eye requires the intricate orchestration of multiple cellular interactions. In this paper, early retinal development is discussed with respect to the structure formation of the optic cup. Although recent studies have elucidated molecular mechanisms of retinal differentiation, little is known about how the unique shape of the optic cup is determined. A recent report has demonstrated that optic-cup morphogenesis spontaneously occurs in three-dimensional stem-cell culture without external forces, indicating a latent intrinsic order to generate the structure. Based on this self-organizing phenomenon, we introduce the "relaxation-expansion" model to mechanically interpret the tissue dynamics that enable the spontaneous invagination of the neural retina. This model involves three consecutive local rules (relaxation, apical constriction, and expansion), and its computer simulation recapitulates the optic-cup morphogenesis in silico.
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Affiliation(s)
- Mototsugu Eiraku
- Organogenesis and Neurogenesis Group, RIKEN Center for Developmental BiologyKobe, Japan
- Unit for Four-Dimensional Tissue Analysis, RIKEN Center for Developmental BiologyKobe, Japan
| | - Taiji Adachi
- Department of Biomechanics, Institute for Frontier Medical Sciences, Kyoto UniversityKyoto, Japan
- Computational Cell Biomechanics Team, VCAD System Research ProgramRIKEN, Wako, Japan
| | - Yoshiki Sasai
- Organogenesis and Neurogenesis Group, RIKEN Center for Developmental BiologyKobe, Japan
- Unit for Four-Dimensional Tissue Analysis, RIKEN Center for Developmental BiologyKobe, Japan
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104
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Vacik T, Stubbs JL, Lemke G. A novel mechanism for the transcriptional regulation of Wnt signaling in development. Genes Dev 2011; 25:1783-95. [PMID: 21856776 DOI: 10.1101/gad.17227011] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Axial patterning of the embryonic brain requires a precise balance between canonical Wnt signaling, which dorsalizes the nervous system, and Sonic hedgehog (Shh), which ventralizes it. The ventral anterior homeobox (Vax) transcription factors are induced by Shh and ventralize the forebrain through a mechanism that is poorly understood. We therefore sought to delineate direct Vax target genes. Among these, we identify an extraordinarily conserved intronic region within the gene encoding Tcf7l2, a key mediator of canonical Wnt signaling. This region functions as a Vax2-activated internal promoter that drives the expression of dnTcf7l2, a truncated Tcf7l2 isoform that cannot bind β-catenin and that therefore acts as a potent dominant-negative Wnt antagonist. Vax2 concomitantly activates the expression of additional Wnt antagonists that cooperate with dnTcf7l2. Specific elimination of dnTcf7l2 in Xenopus results in headless embryos, a phenotype consistent with a fundamental role for this regulator in forebrain development.
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Affiliation(s)
- Tomas Vacik
- Molecular Neurobiology Laboratory, The Salk Institute, La Jolla, California 92037, USA
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105
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Meyer JS, Howden SE, Wallace KA, Verhoeven AD, Wright LS, Capowski EE, Pinilla I, Martin JM, Tian S, Stewart R, Pattnaik B, Thomson J, Gamm DM. Optic vesicle-like structures derived from human pluripotent stem cells facilitate a customized approach to retinal disease treatment. Stem Cells 2011; 29:1206-18. [PMID: 21678528 PMCID: PMC3412675 DOI: 10.1002/stem.674] [Citation(s) in RCA: 351] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Differentiation methods for human induced pluripotent stem cells (hiPSCs) typically yield progeny from multiple tissue lineages, limiting their use for drug testing and autologous cell transplantation. In particular, early retina and forebrain derivatives often intermingle in pluripotent stem cell cultures, owing to their shared ancestry and tightly coupled development. Here, we demonstrate that three-dimensional populations of retinal progenitor cells (RPCs) can be isolated from early forebrain populations in both human embryonic stem cell and hiPSC cultures, providing a valuable tool for developmental, functional, and translational studies. Using our established protocol, we identified a transient population of optic vesicle (OV)-like structures that arose during a time period appropriate for normal human retinogenesis. These structures were independently cultured and analyzed to confirm their multipotent RPC status and capacity to produce physiologically responsive retinal cell types, including photoreceptors and retinal pigment epithelium (RPE). We then applied this method to hiPSCs derived from a patient with gyrate atrophy, a retinal degenerative disease affecting the RPE. RPE generated from these hiPSCs exhibited a disease-specific functional defect that could be corrected either by pharmacological means or following targeted gene repair. The production of OV-like populations from human pluripotent stem cells should facilitate the study of human retinal development and disease and advance the use of hiPSCs in personalized medicine.
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Affiliation(s)
- Jason S. Meyer
- Waisman Center, University of Wisconsin, Madison WI 53705
| | - Sara E. Howden
- Department of Cell & Regenerative Biology, University of Wisconsin, Madison WI 53705
- The Genome Center of Wisconsin, University of Wisconsin, Madison WI 53705
- Morgridge Institute for Research, Madison WI 53706
| | | | | | | | | | - Isabel Pinilla
- Department of Ophthalmology, Blesa University Hospital and the Instituto Aragones de Ciencias de la Salud, Zaragoza, Spain
| | | | - Shulan Tian
- Morgridge Institute for Research, Madison WI 53706
| | - Ron Stewart
- Morgridge Institute for Research, Madison WI 53706
| | - Bikash Pattnaik
- Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison WI 53705
- Department of Pediatrics, University of Wisconsin, Madison WI 53705
- Eye Research Institute, University of Wisconsin, Madison WI 53705
| | - James Thomson
- Department of Cell & Regenerative Biology, University of Wisconsin, Madison WI 53705
- The Genome Center of Wisconsin, University of Wisconsin, Madison WI 53705
- Morgridge Institute for Research, Madison WI 53706
- Department of Molecular, Cellular, & Developmental Biology, University of California Santa Barbara, Santa Barbara CA 93106
| | - David M. Gamm
- Waisman Center, University of Wisconsin, Madison WI 53705
- Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison WI 53705
- Eye Research Institute, University of Wisconsin, Madison WI 53705
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106
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Self-organizing optic-cup morphogenesis in three-dimensional culture. Nature 2011; 472:51-6. [PMID: 21475194 DOI: 10.1038/nature09941] [Citation(s) in RCA: 1378] [Impact Index Per Article: 106.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Accepted: 02/17/2011] [Indexed: 12/20/2022]
Abstract
Balanced organogenesis requires the orchestration of multiple cellular interactions to create the collective cell behaviours that progressively shape developing tissues. It is currently unclear how individual, localized parts are able to coordinate with each other to develop a whole organ shape. Here we report the dynamic, autonomous formation of the optic cup (retinal primordium) structure from a three-dimensional culture of mouse embryonic stem cell aggregates. Embryonic-stem-cell-derived retinal epithelium spontaneously formed hemispherical epithelial vesicles that became patterned along their proximal-distal axis. Whereas the proximal portion differentiated into mechanically rigid pigment epithelium, the flexible distal portion progressively folded inward to form a shape reminiscent of the embryonic optic cup, exhibited interkinetic nuclear migration and generated stratified neural retinal tissue, as seen in vivo. We demonstrate that optic-cup morphogenesis in this simple cell culture depends on an intrinsic self-organizing program involving stepwise and domain-specific regulation of local epithelial properties.
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107
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Squarzoni P, Parveen F, Zanetti L, Ristoratore F, Spagnuolo A. FGF/MAPK/Ets signaling renders pigment cell precursors competent to respond to Wnt signal by directly controlling Ci-Tcf transcription. Development 2011; 138:1421-32. [DOI: 10.1242/dev.057323] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
FGF and Wnt pathways constitute two fundamental signaling cascades, which appear to crosstalk in cooperative or antagonistic fashions in several developmental processes. In vertebrates, both cascades are involved in pigment cell development, but the possible interplay between FGF and Wnt remains to be elucidated. In this study, we have investigated the role of FGF and Wnt signaling in development of the pigment cells in the sensory organs of C. intestinalis. This species possesses the basic features of an ancestral chordate, thus sharing conserved molecular developmental mechanisms with vertebrates. Chemical and targeted perturbation approaches revealed that a FGF signal, spreading in time from early gastrulation to neural tube closure, is responsible for pigment cell precursor induction. This signal is transmitted via the MAPK pathway, which activates the Ci-Ets1/2 transcription factor. Targeted perturbation of Ci-TCF, a downstream factor of the canonical Wnt pathway, indicated its contribution to pigment cell differentiation Furthermore, analyses of the Ci-Tcf regulatory region revealed the involvement of the FGF effector, Ci-Ets1/2, in Ci-Tcf transcriptional regulation in pigment cell precursors. Our results indicate that both FGF and the canonical Wnt pathways are involved in C. intestinalis pigment cell induction and differentiation. Moreover, we present a case of direct transcriptional regulation exerted by the FGF signaling cascade, via the MAPK-ERK-Ets1/2, on the Wnt downstream gene Ci-Tcf. Several examples of FGF/Wnt signaling crosstalk have been described in different developmental processes; however, to our knowledge, FGF-Wnt cross-interaction at the transcriptional level has never been previously reported. These findings further contribute to clarifying the multitude of FGF-Wnt pathway interactions.
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Affiliation(s)
- Paola Squarzoni
- Cellular and Developmental Biology Laboratory, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy
| | - Fateema Parveen
- Cellular and Developmental Biology Laboratory, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy
| | - Laura Zanetti
- Cellular and Developmental Biology Laboratory, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy
| | - Filomena Ristoratore
- Cellular and Developmental Biology Laboratory, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy
| | - Antonietta Spagnuolo
- Cellular and Developmental Biology Laboratory, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy
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108
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Liu W, Lagutin O, Swindell E, Jamrich M, Oliver G. Neuroretina specification in mouse embryos requires Six3-mediated suppression of Wnt8b in the anterior neural plate. J Clin Invest 2010; 120:3568-77. [PMID: 20890044 PMCID: PMC2947236 DOI: 10.1172/jci43219] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2010] [Accepted: 08/04/2010] [Indexed: 01/02/2023] Open
Abstract
Retinal degeneration causes vision impairment and blindness in humans. If one day we are to harness the potential of stem cell-based cell replacement therapies to treat these conditions, it is imperative that we better understand normal retina development. Currently, the genes and mechanisms that regulate the specification of the neuroretina during vertebrate eye development remain unknown. Here, we identify sine oculis-related homeobox 3 (Six3) as a crucial player in this process in mice. In Six3 conditional-mutant mouse embryos, specification of the neuroretina was abrogated, but that of the retinal pigmented epithelium was normal. Conditional deletion of Six3 did not affect the initial development of the optic vesicle but did arrest subsequent neuroretina specification. Ectopic rostral expansion of Wnt8b expression was the major response to Six3 deletion and the leading cause for the specific lack of neuroretina, as ectopic Wnt8b expression in transgenic embryos was sufficient to suppress neuroretina specification. Using chromatin immunoprecipitation assays, we identified Six3-responsive elements in the Wnt8b locus and demonstrated that Six3 directly repressed Wnt8b expression in vivo. Our findings provide a molecular framework to the program leading to neuroretina differentiation and may be relevant for the development of novel strategies aimed at characterizing and eventually treating different abnormalities in eye formation.
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Affiliation(s)
- Wei Liu
- Department of Genetics and Tumor Cell Biology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA.
Department of Pediatrics, The University of Texas Medical School at Houston, Houston, Texas, USA.
Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Oleg Lagutin
- Department of Genetics and Tumor Cell Biology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA.
Department of Pediatrics, The University of Texas Medical School at Houston, Houston, Texas, USA.
Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Eric Swindell
- Department of Genetics and Tumor Cell Biology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA.
Department of Pediatrics, The University of Texas Medical School at Houston, Houston, Texas, USA.
Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Milan Jamrich
- Department of Genetics and Tumor Cell Biology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA.
Department of Pediatrics, The University of Texas Medical School at Houston, Houston, Texas, USA.
Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Guillermo Oliver
- Department of Genetics and Tumor Cell Biology, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA.
Department of Pediatrics, The University of Texas Medical School at Houston, Houston, Texas, USA.
Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
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109
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Westenskow PD, McKean JB, Kubo F, Nakagawa S, Fuhrmann S. Ectopic Mitf in the embryonic chick retina by co-transfection of β-catenin and Otx2. Invest Ophthalmol Vis Sci 2010; 51:5328-35. [PMID: 20463321 PMCID: PMC3066625 DOI: 10.1167/iovs.09-5015] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2009] [Revised: 03/26/2010] [Accepted: 04/15/2010] [Indexed: 12/17/2022] Open
Abstract
PURPOSE Development of the retinal pigment epithelium (RPE) is controlled by intrinsic and extrinsic regulators including orthodenticle homeobox 2 (Otx2) and the Wnt/β-catenin pathway, respectively. Otx2 and β-catenin are necessary for the expression of the RPE key regulator microphthalmia-associated transcription factor (Mitf); however, neither factor is sufficient to promote Mitf expression in vivo. The study was conducted to determine whether Otx2 and β-catenin act in a combinatorial manner and tested whether co-expression in the presumptive chick retina induces ectopic Mitf expression. METHODS The sufficiency of Wnt/β-catenin activation and/or Otx2 expression to induce RPE-specific gene expression was examined in chick optic vesicle explant cultures or in the presumptive neural retina using in ovo-electroporation. Luciferase assays were used to examine the transactivation potentials of Otx2 and β-catenin on the Mitf-D enhancer and autoregulation of the Mitf-D and Otx2T0 enhancers. RESULTS In optic vesicles explant cultures, RPE-specific gene expression was activated by lithium chloride, a Wnt/β-catenin agonist. However, in vivo, Mitf was induced only in the presumptive retina if both β-catenin and Otx2 are co-expressed. Furthermore, both Mitf and Otx2 can autoregulate their own enhancers in vitro. CONCLUSIONS The present study provides evidence that β-catenin and Otx2 are sufficient, at least in part, to convert retinal progenitor cells into presumptive RPE cells expressing Mitf. Otx2 may act as a competence factor that allows RPE specification in concert with additional RPE-promoting factors such as β-catenin.
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Affiliation(s)
- Peter D. Westenskow
- From the Department of Ophthalmology and Visual Sciences, Moran Eye Center, and
- the Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, Utah; and
| | - Jon B. McKean
- From the Department of Ophthalmology and Visual Sciences, Moran Eye Center, and
| | - Fumi Kubo
- the RIKEN Advanced Science Institute, Wako, Saitama, Japan
| | | | - Sabine Fuhrmann
- From the Department of Ophthalmology and Visual Sciences, Moran Eye Center, and
- the Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, Utah; and
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110
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Gongal PA, French CR, Waskiewicz AJ. Aberrant forebrain signaling during early development underlies the generation of holoprosencephaly and coloboma. Biochim Biophys Acta Mol Basis Dis 2010; 1812:390-401. [PMID: 20850526 DOI: 10.1016/j.bbadis.2010.09.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Accepted: 09/08/2010] [Indexed: 01/10/2023]
Abstract
In this review, we highlight recent literature concerning the signaling mechanisms underlying the development of two neural birth defects, holoprosencephaly and coloboma. Holoprosencephaly, the most common forebrain defect, occurs when the cerebral hemispheres fail to separate and is typically associated with mispatterning of embryonic midline tissue. Coloboma results when the choroid fissure in the eye fails to close. It is clear that Sonic hedgehog (Shh) signaling regulates both forebrain and eye development, with defects in Shh, or components of the Shh signaling cascade leading to the generation of both birth defects. In addition, other intercellular signaling pathways are known factors in the incidence of holoprosencephaly and coloboma. This review will outline recent advances in our understanding of forebrain and eye embryonic pattern formation, with a focus on zebrafish studies of Shh and retinoic acid pathways. Given the clear overlap in the mechanisms that generate both diseases, we propose that holoprosencephaly and coloboma can represent mild and severe aspects of single phenotypic spectrum resulting from aberrant forebrain development. This article is part of a Special Issue entitled Zebrafish Models of Neurological Diseases.
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Affiliation(s)
- Patricia A Gongal
- Department of Biological Sciences, University of Alberta, Edmonton, Canada
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111
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Del Debbio CB, Balasubramanian S, Parameswaran S, Chaudhuri A, Qiu F, Ahmad I. Notch and Wnt signaling mediated rod photoreceptor regeneration by Müller cells in adult mammalian retina. PLoS One 2010; 5:e12425. [PMID: 20865053 PMCID: PMC2928741 DOI: 10.1371/journal.pone.0012425] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2010] [Accepted: 07/27/2010] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND Evidence emerging from a variety of approaches used in different species suggests that Müller cell function may extend beyond its role of maintaining retinal homeostasis to that of progenitors in the adult retina. Enriched Müller cells in vitro or those that re-enter cell cycle in response to neurotoxin-damage to retina in vivo display multipotential and self-renewing capacities, the cardinal features of stem cells. METHODOLOGY/PRINCIPAL FINDINGS We demonstrate that Notch and Wnt signaling activate Müller cells through their canonical pathways and that a rare subset of activated Müller cells differentiates along rod photoreceptor lineage in the outer nuclear layer. The differentiation of activated Müller cells along photoreceptor lineage is confirmed by multiple approaches that included Hoechst dye efflux analysis, genetic analysis using retina from Nrl-GFP mice, and lineage tracing using GS-GFP lentivirus in wild type and rd mice in vitro and S334ter rats in vivo. Examination of S334ter rats for head-neck tracking of visual stimuli, a behavioral measure of light perception, demonstrates a significant improvement in light perception in animals treated to activate Müller cells. The number of activated Müller cells with rod photoreceptor phenotype in treated animals correlates with the improvement in their light perception. CONCLUSION/SIGNIFICANCE In summary, our results provide a proof of principle for non-neurotoxin-mediated activation of Müller cells through Notch and Wnt signaling toward the regeneration of rod photoreceptors.
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Affiliation(s)
- Carolina Beltrame Del Debbio
- Department of Ophthalmology and Visual Sciences, College of Public Health, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Sudha Balasubramanian
- Department of Ophthalmology and Visual Sciences, College of Public Health, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Sowmya Parameswaran
- Department of Ophthalmology and Visual Sciences, College of Public Health, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Anathbandhu Chaudhuri
- Department of Ophthalmology and Visual Sciences, College of Public Health, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Fang Qiu
- Department of Biostatistics, College of Public Health, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Iqbal Ahmad
- Department of Ophthalmology and Visual Sciences, College of Public Health, University of Nebraska Medical Center, Omaha, Nebraska, United States of America
- * E-mail:
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112
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Thompson H, Griffiths JS, Jeffery G, McGonnell IM. The retinal pigment epithelium of the eye regulates the development of scleral cartilage. Dev Biol 2010; 347:40-52. [PMID: 20707994 PMCID: PMC2977850 DOI: 10.1016/j.ydbio.2010.08.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2010] [Revised: 07/28/2010] [Accepted: 08/03/2010] [Indexed: 01/01/2023]
Abstract
The majority of vertebrate species have a layer of hyaline cartilage within the fibrous sclera giving an extra degree of support to the eyeball. In chicks, this is seen as a cuplike structure throughout the scleral layer. However, the mechanisms that control the development of scleral cartilage are largely unknown. Here we have studied the phases of scleral cartilage development and characterised expression profiles of genes activated during the cartilage differentiation programme. CART1 and SOX9, the earliest markers of pre-committed cartilage, are expressed in the mesenchyme surrounding the optic cup. Later AGGRECAN, a matrix protein expressed during chondrocyte differentiation, is also expressed. The expression of these genes is lost following early removal of the optic cup, suggesting a role for this tissue in inducing scleral cartilage. By grafting young retinal pigment epithelium (RPE) and retina into cranial mesenchyme in vivo, it was found that RPE alone has the ability to induce cartilage formation. There are some exceptions within the vertebrates where scleral cartilage is not present; one such example is the placental mammals. However, we found that the cartilage differentiation pathway is initiated in mice as seen by the expression of Cart1 and Sox9, but expression of the later cartilage marker Aggrecan is weak. Furthermore, cartilage forms in mouse peri-ocular mesenchyme micromass culture. This suggests that the process halts in vivo before full differentiation into cartilage, but that murine scleral mesenchyme has retained the potential to make cartilage in vitro. RA, Wnts and Bmps have been linked to the cartilage development process and are expressed within the developing RPE. We find that RA may have a role in early scleral cartilage development but is not likely to be the main factor involved. These data reveal the course of scleral cartilage formation and highlight the key role that the optic cup plays in this process. The driving element within the optic cup is almost certainly the retinal pigmented epithelium.
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Affiliation(s)
- H Thompson
- Department of Veterinary Basic Science, Royal Veterinary College, London, NW1 0TU, UK
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113
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Bassett EA, Williams T, Zacharias AL, Gage PJ, Fuhrmann S, West-Mays JA. AP-2alpha knockout mice exhibit optic cup patterning defects and failure of optic stalk morphogenesis. Hum Mol Genet 2010; 19:1791-804. [PMID: 20150232 DOI: 10.1093/hmg/ddq060] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Appropriate development of the retina and optic nerve requires that the forebrain-derived optic neuroepithelium undergoes a precisely coordinated sequence of patterning and morphogenetic events, processes which are highly influenced by signals from adjacent tissues. Our previous work has suggested that transcription factor activating protein-2 alpha (AP-2alpha; Tcfap2a) has a non-cell autonomous role in optic cup (OC) development; however, it remained unclear how OC abnormalities in AP-2alpha knockout (KO) mice arise at the morphological and molecular level. In this study, we show that patterning and morphogenetic defects in the AP-2alpha KO optic neuroepithelium begin at the optic vesicle stage. During subsequent OC formation, ectopic neural retina and optic stalk-like tissue replaced regions of retinal pigment epithelium. AP-2alpha KO eyes also displayed coloboma in the ventral retina, and a rare phenotype in which the optic stalk completely failed to extend, causing the OCs to be drawn inward to the midline. We detected evidence of increased sonic hedgehog signaling in the AP-2alpha KO forebrain neuroepithelium, which likely contributed to multiple aspects of the ocular phenotype, including expansion of PAX2-positive optic stalk-like tissue into the OC. Our data suggest that loss of AP-2alpha in multiple tissues in the craniofacial region leads to severe OC and optic stalk abnormalities by disturbing the tissue-tissue interactions required for ocular development. In view of recent data showing that mutations in human TFAP2A result in similar eye defects, the current findings demonstrate that AP-2alpha KO mice provide a valuable model for human ocular disease.
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Affiliation(s)
- Erin A Bassett
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada
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114
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Abstract
Organogenesis of the eye is a multistep process that starts with the formation of optic vesicles followed by invagination of the distal domain of the vesicles and the overlying lens placode resulting in morphogenesis of the optic cup. The late optic vesicle becomes patterned into distinct ocular tissues: the neural retina, retinal pigment epithelium (RPE), and optic stalk. Multiple congenital eye disorders, including anophthalmia or microphthalmia, aniridia, coloboma, and retinal dysplasia, stem from disruptions in embryonic eye development. Thus, it is critical to understand the mechanisms that lead to initial specification and differentiation of ocular tissues. An accumulating number of studies demonstrate that a complex interplay between inductive signals provided by tissue-tissue interactions and cell-intrinsic factors is critical to ensuring proper specification of ocular tissues as well as maintenance of RPE cell fate. While several of the extrinsic and intrinsic determinants have been identified, we are just at the beginning in understanding how these signals are integrated. In addition, we know very little about the actual output of these interactions. In this chapter, we provide an update of the mechanisms controlling the early steps of eye development in vertebrates, with emphasis on optic vesicle evagination, specification of neural retina and RPE at the optic vesicle stage, the process of invagination during morphogenesis of the optic cup, and maintenance of the RPE cell fate.
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Affiliation(s)
- Sabine Fuhrmann
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah, Salt Lake City, Utah, USA
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