1
|
Krylov A, Yu S, Veen K, Newton A, Ye A, Qin H, He J, Jusuf PR. Heterogeneity in quiescent Müller glia in the uninjured zebrafish retina drive differential responses following photoreceptor ablation. Front Mol Neurosci 2023; 16:1087136. [PMID: 37575968 PMCID: PMC10413128 DOI: 10.3389/fnmol.2023.1087136] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 06/23/2023] [Indexed: 08/15/2023] Open
Abstract
Introduction Loss of neurons in the neural retina is a leading cause of vision loss. While humans do not possess the capacity for retinal regeneration, zebrafish can achieve this through activation of resident Müller glia. Remarkably, despite the presence of Müller glia in humans and other mammalian vertebrates, these cells lack an intrinsic ability to contribute to regeneration. Upon activation, zebrafish Müller glia can adopt a stem cell-like state, undergo proliferation and generate new neurons. However, the underlying molecular mechanisms of this activation subsequent retinal regeneration remains unclear. Methods/Results To address this, we performed single-cell RNA sequencing (scRNA-seq) and report remarkable heterogeneity in gene expression within quiescent Müller glia across distinct dorsal, central and ventral retina pools of such cells. Next, we utilized a genetically driven, chemically inducible nitroreductase approach to study Müller glia activation following selective ablation of three distinct photoreceptor subtypes: long wavelength sensitive cones, short wavelength sensitive cones, and rods. There, our data revealed that a region-specific bias in activation of Müller glia exists in the zebrafish retina, and this is independent of the distribution of the ablated cell type across retinal regions. Notably, gene ontology analysis revealed that injury-responsive dorsal and central Müller glia express genes related to dorsal/ventral pattern formation, growth factor activity, and regulation of developmental process. Through scRNA-seq analysis, we identify a shared genetic program underlying initial Müller glia activation and cell cycle entry, followed by differences that drive the fate of regenerating neurons. We observed an initial expression of AP-1 and injury-responsive transcription factors, followed by genes involved in Notch signaling, ribosome biogenesis and gliogenesis, and finally expression of cell cycle, chromatin remodeling and microtubule-associated genes. Discussion Taken together, our findings document the regional specificity of gene expression within quiescent Müller glia and demonstrate unique Müller glia activation and regeneration features following neural ablation. These findings will improve our understanding of the molecular pathways relevant to neural regeneration in the retina.
Collapse
Affiliation(s)
- Aaron Krylov
- School of BioSciences, University of Melbourne, Parkville, VIC, Australia
| | - Shuguang Yu
- State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Institute of Neuroscience, Chinese Academy of Sciences, Shanghai, China
| | - Kellie Veen
- School of BioSciences, University of Melbourne, Parkville, VIC, Australia
| | - Axel Newton
- School of BioSciences, University of Melbourne, Parkville, VIC, Australia
| | - Aojun Ye
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Huiwen Qin
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Jie He
- State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Institute of Neuroscience, Chinese Academy of Sciences, Shanghai, China
| | - Patricia R. Jusuf
- School of BioSciences, University of Melbourne, Parkville, VIC, Australia
| |
Collapse
|
2
|
Amamoto R, Wallick GK, Cepko CL. Retinoic acid signaling mediates peripheral cone photoreceptor survival in a mouse model of retina degeneration. eLife 2022; 11:76389. [PMID: 35315776 PMCID: PMC8940176 DOI: 10.7554/elife.76389] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 02/25/2022] [Indexed: 12/16/2022] Open
Abstract
Retinitis Pigmentosa (RP) is a progressive, debilitating visual disorder caused by mutations in a diverse set of genes. In both humans with RP and mouse models of RP, rod photoreceptor dysfunction leads to loss of night vision, and is followed by secondary cone photoreceptor dysfunction and degeneration, leading to loss of daylight color vision. A strategy to prevent secondary cone death could provide a general RP therapy to preserve daylight color vision regardless of the underlying mutation. In mouse models of RP, cones in the peripheral retina survive long-term, despite complete rod loss. The mechanism for such peripheral cone survival had not been explored. Here, we found that active retinoic acid (RA) signaling in peripheral Muller glia is necessary for the abnormally long survival of these peripheral cones. RA depletion by conditional knockout of RA synthesis enzymes, or overexpression of an RA degradation enzyme, abrogated the extended survival of peripheral cones. Conversely, constitutive activation of RA signaling in the central retina promoted long-term cone survival. These results indicate that RA signaling mediates the prolonged peripheral cone survival in the rd1 mouse model of retinal degeneration, and provide a basis for a generic strategy for cone survival in the many diseases that lead to loss of cone-mediated vision.
Collapse
Affiliation(s)
- Ryoji Amamoto
- Department of Genetics and Ophthalmology, Howard Hughes Medical Institute, Blavatnik Institute, Harvard Medical School, Boston, United States
| | - Grace K Wallick
- Department of Genetics and Ophthalmology, Howard Hughes Medical Institute, Blavatnik Institute, Harvard Medical School, Boston, United States
| | - Constance L Cepko
- Department of Genetics and Ophthalmology, Howard Hughes Medical Institute, Blavatnik Institute, Harvard Medical School, Boston, United States
| |
Collapse
|
3
|
Kukreja S, Udaykumar N, Yogesh B, Sen J. Retinoic acid signaling regulates proliferation and lamina formation in the developing chick optic tectum. Dev Biol 2020; 467:95-107. [PMID: 32919944 DOI: 10.1016/j.ydbio.2020.09.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 09/03/2020] [Accepted: 09/06/2020] [Indexed: 01/05/2023]
Abstract
The retinotectal system has been extensively studied for investigating the mechanism(s) for topographic map formation. The optic tectum, which is composed of multiple laminae, is the major retino recipient structure in the developing avian brain. Laminar development of the tectum results from cell proliferation, differentiation and migration, coordinated in strict temporal and spatial patterns. However, the molecular mechanisms that orchestrate these complex developmental events, have not been fully elucidated. In this study, we have identified the presence of differential retinoic acid (RA) signaling along the rostro-caudal and dorsoventral axis of the tectum. We show for the first time that loss of RA signaling in the anterior optic tectum, leads to an increase in cell proliferation and gross changes in the morphology manifested as defects in lamination. Detailed analysis points to delayed migration of cells as the plausible cause for the defects in lamina formation. Thus, we conclude that in the optic tectum, RA signaling is involved in maintaining cell proliferation and in regulating the formation of the tectal laminae.
Collapse
Affiliation(s)
- Shweta Kukreja
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, Kanpur, 208016, Uttar Pradesh, India; Present address: Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, USA
| | - Niveda Udaykumar
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, Kanpur, 208016, Uttar Pradesh, India
| | - Baba Yogesh
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, Kanpur, 208016, Uttar Pradesh, India; Present address: Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Jonaki Sen
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, Kanpur, 208016, Uttar Pradesh, India.
| |
Collapse
|
4
|
Isabella AJ, Barsh GR, Stonick JA, Dubrulle J, Moens CB. Retinoic Acid Organizes the Zebrafish Vagus Motor Topographic Map via Spatiotemporal Coordination of Hgf/Met Signaling. Dev Cell 2020; 53:344-357.e5. [PMID: 32302545 PMCID: PMC7237105 DOI: 10.1016/j.devcel.2020.03.017] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2019] [Revised: 02/14/2020] [Accepted: 03/19/2020] [Indexed: 02/08/2023]
Abstract
Information flow through neural circuits often requires their organization into topographic maps in which the positions of cell bodies and synaptic targets correspond. To understand how topographic map development is controlled, we examine the mechanism underlying targeting of vagus motor axons to the pharyngeal arches in zebrafish. We reveal that retinoic acid organizes topography by specifying anterior-posterior identity in vagus motor neurons. We then show that chemoattractant signaling between Hgf and Met is required for vagus innervation of the pharyngeal arches. Finally, we find that retinoic acid controls the spatiotemporal dynamics of Hgf/Met signaling to coordinate axon targeting with the developmental progression of the pharyngeal arches and show that experimentally altering the timing of Hgf/Met signaling is sufficient to redirect axon targeting and disrupt the topographic map. These findings establish a mechanism of topographic map development in which the regulation of chemoattractant signaling in space and time guides axon targeting.
Collapse
Affiliation(s)
- Adam J Isabella
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Gabrielle R Barsh
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Molecular and Cellular Biology Graduate Program and Medical Scientist Training Program, University of Washington, Seattle, WA 98195, USA
| | - Jason A Stonick
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Julien Dubrulle
- Shared Resources, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Cecilia B Moens
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA; Molecular and Cellular Biology Graduate Program and Medical Scientist Training Program, University of Washington, Seattle, WA 98195, USA.
| |
Collapse
|
5
|
Todd L, Suarez L, Quinn C, Fischer AJ. Retinoic Acid-Signaling Regulates the Proliferative and Neurogenic Capacity of Müller Glia-Derived Progenitor Cells in the Avian Retina. Stem Cells 2017; 36:392-405. [PMID: 29193451 DOI: 10.1002/stem.2742] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 10/16/2017] [Accepted: 11/03/2017] [Indexed: 12/26/2022]
Abstract
In the retina, Müller glia have the potential to become progenitor cells with the ability to proliferate and regenerate neurons. However, the ability of Müller glia-derived progenitor cells (MGPCs) to proliferate and produce neurons is limited in higher vertebrates. Using the chick model system, we investigate how retinoic acid (RA)-signaling influences the proliferation and the formation of MGPCs. We observed an upregulation of cellular RA binding proteins (CRABP) in the Müller glia of damaged retinas where the formation of MGPCs is known to occur. Activation of RA-signaling was stimulated, whereas inhibition suppressed the proliferation of MGPCs in damaged retinas and in fibroblast growth factor 2-treated undamaged retinas. Furthermore, inhibition of RA-degradation stimulated the proliferation of MGPCs. Levels of Pax6, Klf4, and cFos were upregulated in MGPCs by RA agonists and downregulated in MGPCs by RA antagonists. Activation of RA-signaling following MGPC proliferation increased the percentage of progeny that differentiated as neurons. Similarly, the combination of RA and insulin-like growth factor 1 (IGF1) significantly increased neurogenesis from retinal progenitors in the circumferential marginal zone (CMZ). In summary, RA-signaling stimulates the formation of proliferating MGPCs and enhances the neurogenic potential of MGPCs and stem cells in the CMZ. Stem Cells 2018;36:392-405.
Collapse
Affiliation(s)
- Levi Todd
- Department of Neuroscience, College of Medicine, The Ohio State University, Columbus, Ohio, USA
| | - Lilianna Suarez
- Department of Neuroscience, College of Medicine, The Ohio State University, Columbus, Ohio, USA
| | - Colin Quinn
- Department of Neuroscience, College of Medicine, The Ohio State University, Columbus, Ohio, USA
| | - Andy J Fischer
- Department of Neuroscience, College of Medicine, The Ohio State University, Columbus, Ohio, USA
| |
Collapse
|
6
|
Diverse Functions of Retinoic Acid in Brain Vascular Development. J Neurosci 2017; 36:7786-801. [PMID: 27445154 DOI: 10.1523/jneurosci.3952-15.2016] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 06/15/2016] [Indexed: 01/24/2023] Open
Abstract
UNLABELLED As neural structures grow in size and increase metabolic demand, the CNS vasculature undergoes extensive growth, remodeling, and maturation. Signals from neural tissue act on endothelial cells to stimulate blood vessel ingression, vessel patterning, and acquisition of mature brain vascular traits, most notably the blood-brain barrier. Using mouse genetic and in vitro approaches, we identified retinoic acid (RA) as an important regulator of brain vascular development via non-cell-autonomous and cell-autonomous regulation of endothelial WNT signaling. Our analysis of globally RA-deficient embryos (Rdh10 mutants) points to an important, non-cell-autonomous function for RA in the development of the vasculature in the neocortex. We demonstrate that Rdh10 mutants have severe defects in cerebrovascular development and that this phenotype correlates with near absence of endothelial WNT signaling, specifically in the cerebrovasculature, and substantially elevated expression of WNT inhibitors in the neocortex. We show that RA can suppress the expression of WNT inhibitors in neocortical progenitors. Analysis of vasculature in non-neocortical brain regions suggested that RA may have a separate, cell-autonomous function in brain endothelial cells to inhibit WNT signaling. Using both gain and loss of RA signaling approaches, we show that RA signaling in brain endothelial cells can inhibit WNT-β-catenin transcriptional activity and that this is required to moderate the expression of WNT target Sox17. From this, a model emerges in which RA acts upstream of the WNT pathway via non-cell-autonomous and cell-autonomous mechanisms to ensure the formation of an adequate and stable brain vascular plexus. SIGNIFICANCE STATEMENT Work presented here provides novel insight into important yet little understood aspects of brain vascular development, implicating for the first time a factor upstream of endothelial WNT signaling. We show that RA is permissive for cerebrovascular growth via suppression of WNT inhibitor expression in the neocortex. RA also functions cell-autonomously in brain endothelial cells to modulate WNT signaling and its downstream target, Sox17. The significance of this is although endothelial WNT signaling is required for neurovascular development, too much endothelial WNT signaling, as well as overexpression of its target Sox17, are detrimental. Therefore, RA may act as a "brake" on endothelial WNT signaling and Sox17 to ensure normal brain vascular development.
Collapse
|
7
|
da Silva S, Cepko CL. Fgf8 Expression and Degradation of Retinoic Acid Are Required for Patterning a High-Acuity Area in the Retina. Dev Cell 2017; 42:68-81.e6. [PMID: 28648799 PMCID: PMC5798461 DOI: 10.1016/j.devcel.2017.05.024] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 04/29/2017] [Accepted: 05/26/2017] [Indexed: 01/08/2023]
Abstract
Species that are highly reliant on their visual system have a specialized retinal area subserving high-acuity vision, e.g., the fovea in humans. Although of critical importance for our daily activities, little is known about the mechanisms driving the development of retinal high-acuity areas (HAAs). Using the chick as a model, we found a precise and dynamic expression pattern of fibroblast growth factor 8 (Fgf8) in the HAA anlage, which was regulated by enzymes that degrade retinoic acid (RA). Transient manipulation of RA signaling, or reduction of Fgf8 expression, disrupted several features of HAA patterning, including photoreceptor distribution, ganglion cell density, and organization of interneurons. Notably, patterned expression of RA signaling components was also found in humans, suggesting that RA also plays a role in setting up the human fovea.
Collapse
Affiliation(s)
- Susana da Silva
- Departments of Genetics and Ophthalmology, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Constance L Cepko
- Departments of Genetics and Ophthalmology, Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA.
| |
Collapse
|
8
|
Gupta S, Sen J. Retinoic acid signaling regulates development of the dorsal forebrain midline and the choroid plexus in the chick. Development 2015; 142:1293-8. [PMID: 25758461 DOI: 10.1242/dev.122390] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The developing forebrain roof plate (RP) contains a transient signaling center, perturbations in which have been linked to holoprosencephaly (HPE). Here, we describe a novel domain of retinoic acid (RA) signaling that is specific to the chick RP and demonstrate that RA signaling is sufficient for inducing characteristics of the RP in ectopic locations. We further demonstrate that, unlike what has been observed in the mouse, RA signaling is essential for invagination of the RP in chick, failure of which leads to an HPE-like phenotype. In addition, we found that RA exerts a negative influence on choroid plexus differentiation. Thus, our findings identify RA as a novel regulator of chick forebrain RP development.
Collapse
Affiliation(s)
- Sandeep Gupta
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
| | - Jonaki Sen
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh 208016, India
| |
Collapse
|
9
|
Schulte D, Frank D. TALE transcription factors during early development of the vertebrate brain and eye. Dev Dyn 2013; 243:99-116. [DOI: 10.1002/dvdy.24030] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Revised: 07/11/2013] [Accepted: 07/13/2013] [Indexed: 12/25/2022] Open
Affiliation(s)
- Dorothea Schulte
- Institute of Neurology (Edinger Institute); University Hospital Frankfurt, J.W. Goethe University; Frankfurt Germany
| | - Dale Frank
- Department of Biochemistry; The Rappaport Family Institute for Research in the Medical Sciences, Faculty of Medicine, Technion-Israel Institute of Technology; Haifa Israel
| |
Collapse
|
10
|
Abstract
Vitamin A deficiency causes impaired vision and blindness in millions of children around the world. Previous studies in zebrafish have demonstrated that retinoic acid (RA), the acid form of vitamin A, plays a vital role in early eye development. The objective of this study was to describe the effects of early RA deficiency by treating zebrafish with diethylaminobenzaldehyde (DEAB), a potent inhibitor of the enzyme retinaldehyde dehydrogenase (RALDH) that converts retinal to RA. Zebrafish embryos were treated for 2 h beginning at 9 h postfertilization. Gross morphology and retinal development were examined at regular intervals for 5 days after treatment. The optokinetic reflex (OKR) test, visual background adaptation (VBA) test, and the electroretinogram (ERG) were performed to assess visual function and behavior. Early treatment of zebrafish embryos with 100 μM DEAB (9 h) resulted in reduced eye size, and this microphthalmia persisted through larval development. Retinal histology revealed that DEAB eyes had significant developmental abnormalities but had relatively normal retinal lamination by 5.5 days postfertilization. However, the fish showed neither an OKR nor a VBA response. Further, the retina did not respond to light as measured by the ERG. We conclude that early deficiency of RA during eye development causes microphthalmia as well as other visual defects, and that timing of the RA deficiency is critical to the developmental outcome.
Collapse
|
11
|
Vergara MN, Canto-Soler MV. Rediscovering the chick embryo as a model to study retinal development. Neural Dev 2012; 7:22. [PMID: 22738172 PMCID: PMC3541172 DOI: 10.1186/1749-8104-7-22] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Accepted: 05/22/2012] [Indexed: 01/20/2023] Open
Abstract
The embryonic chick occupies a privileged place among animal models used in developmental studies. Its rapid development and accessibility for visualization and experimental manipulation are just some of the characteristics that have made it a vertebrate model of choice for more than two millennia. Until a few years ago, the inability to perform genetic manipulations constituted a major drawback of this system. However, the completion of the chicken genome project and the development of techniques to manipulate gene expression have allowed this classic animal model to enter the molecular age. Such techniques, combined with the embryological manipulations that this system is well known for, provide a unique toolkit to study the genetic basis of neural development. A major advantage of these approaches is that they permit targeted gene misexpression with extremely high spatiotemporal resolution and over a large range of developmental stages, allowing functional analysis at a level, speed and ease that is difficult to achieve in other systems. This article provides a general overview of the chick as a developmental model focusing more specifically on its application to the study of eye development. Special emphasis is given to the state of the art of the techniques that have made gene gain- and loss-of-function studies in this model a reality. In addition, we discuss some methodological considerations derived from our own experience that we believe will be beneficial to researchers working with this system.
Collapse
Affiliation(s)
- M Natalia Vergara
- Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Smith Building 3023, 400 N Broadway, Baltimore, MD 21287-9257, USA
| | - M Valeria Canto-Soler
- Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Smith Building 3023, 400 N Broadway, Baltimore, MD 21287-9257, USA
| |
Collapse
|
12
|
Forrest D, Swaroop A. Minireview: the role of nuclear receptors in photoreceptor differentiation and disease. Mol Endocrinol 2012; 26:905-15. [PMID: 22556342 DOI: 10.1210/me.2012-1010] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Rod and cone photoreceptors are specialized sensory cells that mediate vision. Transcriptional controls are critical for the development and long-term survival of photoreceptors; when these controls become ineffective, retinal dysfunction or degenerative disease may result. This review discusses the role of nuclear receptors, a class of ligand-regulated transcription factors, at key stages of photoreceptor life in the mammalian retina. Nuclear receptors with known ligands, such as retinoids or thyroid hormone, together with several orphan receptors without identified physiological ligands, complement other classes of transcription factors in directing the differentiation and functional maintenance of photoreceptors. The potential of nuclear receptors to respond to ligands introduces versatility into the control of photoreceptor development and function and may suggest new opportunities for treatments of photoreceptor disease.
Collapse
Affiliation(s)
- Douglas Forrest
- Laboratory of Endocrinology and Receptor Biology, National Institutes of Health, Bethesda, MD 20892, USA.
| | | |
Collapse
|
13
|
Alfano G, Conte I, Caramico T, Avellino R, Arnò B, Pizzo MT, Tanimoto N, Beck SC, Huber G, Dollé P, Seeliger MW, Banfi S. Vax2 regulates retinoic acid distribution and cone opsin expression in the vertebrate eye. Development 2010; 138:261-71. [PMID: 21148184 DOI: 10.1242/dev.051037] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Vax2 is an eye-specific homeobox gene, the inactivation of which in mouse leads to alterations in the establishment of a proper dorsoventral eye axis during embryonic development. To dissect the molecular pathways in which Vax2 is involved, we performed a transcriptome analysis of Vax2(-/-) mice throughout the main stages of eye development. We found that some of the enzymes involved in retinoic acid (RA) metabolism in the eye show significant variations of their expression levels in mutant mice. In particular, we detected an expansion of the expression domains of the RA-catabolizing enzymes Cyp26a1 and Cyp26c1, and a downregulation of the RA-synthesizing enzyme Raldh3. These changes determine a significant expansion of the RA-free zone towards the ventral part of the eye. At postnatal stages of eye development, Vax2 inactivation led to alterations of the regional expression of the cone photoreceptor genes Opn1sw (S-Opsin) and Opn1mw (M-Opsin), which were significantly rescued after RA administration. We confirmed the above described alterations of gene expression in the Oryzias latipes (medaka fish) model system using both Vax2 gain- and loss-of-function assays. Finally, a detailed morphological and functional analysis of the adult retina in mutant mice revealed that Vax2 is necessary for intraretinal pathfinding of retinal ganglion cells in mammals. These data demonstrate for the first time that Vax2 is both necessary and sufficient for the control of intraretinal RA metabolism, which in turn contributes to the appropriate expression of cone opsins in the vertebrate eye.
Collapse
Affiliation(s)
- Giovanna Alfano
- Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Behesti H, Papaioannou VE, Sowden JC. Loss of Tbx2 delays optic vesicle invagination leading to small optic cups. Dev Biol 2009; 333:360-72. [PMID: 19576202 DOI: 10.1016/j.ydbio.2009.06.026] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2009] [Revised: 06/19/2009] [Accepted: 06/22/2009] [Indexed: 01/05/2023]
Abstract
Tbx2 is a T-box transcription factor gene that is dynamically expressed in the presumptive retina during optic vesicle invagination. Several findings implicate Tbx2 in cell cycle regulation, including its overexpression in tumours and regulation of proliferation during heart development. We investigated the role of Tbx2 in optic cup formation by analysing mice with a targeted homozygous mutation in Tbx2. Loss of Tbx2 caused a reduced presumptive retinal volume due to increased apoptosis, and a delay in ventral optic vesicle invagination leading to the formation of small and abnormally shaped optic cups. Tbx2 is essential for maintenance, but not induction of expression of the dorsal retinal determinant, Tbx5, and acts downstream of Bmp4, a dorsally expressed gene implicated in human microphthalmia. The small retina showed a hypocellular ventral region, loss of Fgf15, normally expressed in proliferating central retinal cells, and increased numbers of mitotic cells in the dorsal region, indicating that Tbx2 is required for normal growth and development across the D-V axis. Dorsal expression of potential regulators of retinal growth, Cyp1b1 and Cx43, and the topographic guidance molecule ephrinB2, was increased, and intraretinal axons were disorganised resulting in a failure of optic nerve formation. Our data provide evidence that Tbx2 is required for proper optic cup formation and plays a critical early role in regulating regional retinal growth and the acquisition of shape during optic vesicle invagination.
Collapse
Affiliation(s)
- Hourinaz Behesti
- Developmental Biology Unit, UCL Institute of Child Health, University College London, London, WC1N 1EH, UK
| | | | | |
Collapse
|
15
|
Wilkinson GA, Schittny JC, Reinhardt DP, Klein R. Role for ephrinB2 in postnatal lung alveolar development and elastic matrix integrity. Dev Dyn 2008; 237:2220-34. [PMID: 18651661 DOI: 10.1002/dvdy.21643] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Alveoli are formed in the lung by the insertion of secondary tissue folds, termed septa, which are subsequently remodeled to form the mature alveolar wall. Secondary septation requires interplay between three cell types: endothelial cells forming capillaries, contractile interstitial myofibroblasts, and epithelial cells. Here, we report that postnatal lung alveolization critically requires ephrinB2, a ligand for Eph receptor tyrosine kinases expressed by the microvasculature. Mice homozygous for the hypomorphic knockin allele ephrinB2DeltaV/DeltaV, encoding mutant ephrinB2 with a disrupted C-terminal PDZ interaction motif, show severe postnatal lung defects including an almost complete absence of lung alveoli and abnormal and disorganized elastic matrix. Lung alveolar formation is not sensitive to loss of ephrinB2 cytoplasmic tyrosine phosphorylation sites. Postnatal day 1 mutant lungs show extracellular matrix alterations without differences in proportions of major distal cell populations. We conclude that lung alveolar formation relies on endothelial ephrinB2 function.
Collapse
Affiliation(s)
- George A Wilkinson
- Department of Molecular Neurobiology, Max-Planck Institute of Neurobiology, Munich-Martinsried, Germany.
| | | | | | | |
Collapse
|
16
|
Duester G. Keeping an eye on retinoic acid signaling during eye development. Chem Biol Interact 2008; 178:178-81. [PMID: 18831967 DOI: 10.1016/j.cbi.2008.09.004] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2008] [Accepted: 09/02/2008] [Indexed: 01/06/2023]
Abstract
Retinoic acid is a metabolic derivative of vitamin A that plays an essential function in cell-cell signaling by serving as a ligand for nuclear receptors that directly regulate gene expression. The final step in the conversion of retinol to retinoic acid is carried out by three retinaldehyde dehydrogenases encoded by Raldh1 (Aldh1a1), Raldh2 (Aldh1a2), and Raldh3 (Aldh1a3). Mouse Raldh gene knockout studies have been instrumental in understanding the mechanism of retinoic acid action during eye development. Retinoic acid signaling in the developing eye is particularly complex as all three Raldh genes contribute to retinoic acid synthesis in non-overlapping locations. During optic cup formation Raldh2 is first expressed transiently in perioptic mesenchyme, then later Raldh1 and Raldh3 expression begins in the dorsal and ventral retina, respectively, and these sources of retinoic acid are maintained in the fetus. Retinoic acid is not required for dorsoventral patterning of the retina as originally thought, but it is required for morphogenetic movements that form the optic cup, ventral retina, cornea, and eyelids. These findings will help guide future studies designed to identify retinoic acid target genes during eye organogenesis.
Collapse
Affiliation(s)
- Gregg Duester
- Development and Aging Program, Burnham Institute for Medical Research, La Jolla, CA 92037, USA.
| |
Collapse
|
17
|
Chavarria-Soley G, Sticht H, Aklillu E, Ingelman-Sundberg M, Pasutto F, Reis A, Rautenstrauss B. Mutations in CYP1B1 cause primary congenital glaucoma by reduction of either activity or abundance of the enzyme. Hum Mutat 2008; 29:1147-53. [DOI: 10.1002/humu.20786] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
|
18
|
Wang G, Scott SA. Retinoid signaling is involved in governing the waiting period for axons in chick hindlimb. Dev Biol 2008; 321:216-26. [PMID: 18602384 DOI: 10.1016/j.ydbio.2008.06.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2008] [Revised: 05/12/2008] [Accepted: 06/12/2008] [Indexed: 01/01/2023]
Abstract
During embryonic development in chick, axons pause in a plexus region for approximately 1 day prior to invading the limb. We have previously shown that this "waiting period" is governed by maturational changes in the limb. Here we provide a detailed description of the spatiotemporal pattern of Raldh2 expression in lumbosacral motoneurons and in the limb, and show that retinoid signaling in the limb contributes significantly to terminating the waiting period. Raldh2, indicative of retinoid signaling, first appears in hindlimb mesenchyme near the end of the waiting period. Transcripts are more abundant in connective tissue associated with predominantly fast muscles than predominantly slow muscles, but are not expressed in muscle cells themselves. The tips of ingrowing axons are always found in association with domains of Raldh2, but development of Raldh2 expression is not regulated by the axons. Instead, retinoid signaling appears to regulate axon entry into the limb. Supplying exogenous retinoic acid to proximal limb during the waiting period caused both motor and sensory axons to invade the limb prematurely and altered the normal stereotyped pattern of axon ingrowth without obvious effects on limb morphogenesis or motoneuron specification. Conversely, locally decreasing retinoid synthesis reduced axon growth into the limb. Retinoic acid significantly enhanced motor axon growth in vitro, suggesting that retinoic acid may directly promote axon growth into the limb in vivo. In addition, retinoid signaling may indirectly affect the waiting period by regulating the maturation of other gate keeping or guidance molecules in the limb. Together these findings reveal a novel function of retinoid signaling in governing the timing and patterning of axon growth into the limb.
Collapse
Affiliation(s)
- Guoying Wang
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, 20 North 1900 East, Salt Lake City, UT 84132, USA
| | | |
Collapse
|
19
|
Regulation of RALDH‐1, RALDH‐3 and CYP26A1 by transcription factors cVax/Vax2 and Tbx5 in the embryonic chick retina. Int J Dev Neurosci 2008; 26:435-45. [DOI: 10.1016/j.ijdevneu.2008.03.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2008] [Revised: 03/07/2008] [Accepted: 03/07/2008] [Indexed: 12/22/2022] Open
|
20
|
Trimarchi JM, Stadler MB, Cepko CL. Individual retinal progenitor cells display extensive heterogeneity of gene expression. PLoS One 2008; 3:e1588. [PMID: 18270576 PMCID: PMC2220035 DOI: 10.1371/journal.pone.0001588] [Citation(s) in RCA: 135] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2007] [Accepted: 01/15/2008] [Indexed: 12/28/2022] Open
Abstract
The development of complex tissues requires that mitotic progenitor cells integrate information from the environment. The highly varied outcomes of such integration processes undoubtedly depend at least in part upon variations among the gene expression programs of individual progenitor cells. To date, there has not been a comprehensive examination of these differences among progenitor cells of a particular tissue. Here, we used comprehensive gene expression profiling to define these differences among individual progenitor cells of the vertebrate retina. Retinal progenitor cells (RPCs) have been shown by lineage analysis to be multipotent throughout development and to produce distinct types of daughter cells in a temporal, conserved order. A total of 42 single RPCs were profiled on Affymetrix arrays. In situ hybridizations performed on both retinal sections and dissociated retinal cells were used to validate the results of the microarrays. An extensive amount of heterogeneity in gene expression among RPCs, even among cells isolated from the same developmental time point, was observed. While many classes of genes displayed heterogeneity of gene expression, the expression of transcription factors constituted a significant amount of the observed heterogeneity. In contrast to previous findings, individual RPCs were found to express multiple bHLH transcription factors, suggesting alternative models to those previously developed concerning how these factors may be coordinated. Additionally, the expression of cell cycle related transcripts showed differences among those associated with G2 and M, versus G1 and S phase, suggesting different levels of regulation for these genes. These data provide insights into the types of processes and genes that are fundamental to cell fate choices, proliferation decisions, and, for cells of the central nervous system, the underpinnings of the formation of complex circuitry.
Collapse
Affiliation(s)
- Jeffrey M. Trimarchi
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Michael B. Stadler
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Constance L. Cepko
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
- Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts, United States of America
- *E-mail:
| |
Collapse
|
21
|
Schulte D, Bumsted-O'Brien KM. Molecular mechanisms of vertebrate retina development: Implications for ganglion cell and photoreceptor patterning. Brain Res 2008; 1192:151-64. [PMID: 17553468 DOI: 10.1016/j.brainres.2007.04.079] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2007] [Revised: 04/05/2007] [Accepted: 04/20/2007] [Indexed: 12/20/2022]
Abstract
Although the neural retina appears as a relatively uniform tissue when viewed from its surface, it is in fact highly patterned along its anterior-posterior and dorso-ventral axes. The question of how and when such patterns arise has been the subject of intensive investigations over several decades. Most studies aimed at understanding retinal pattern formation have used the retinotectal map, the ordered projections of retinal ganglion cells to the brain, as a functional readout of the pattern. However, other cell types are also topographically organized in the retina. The most commonly recognized example of such a topographic cellular organization is the differential distribution of photoreceptor types across the retina. Photoreceptor patterns are highly species-specific and may represent an important adaptation to the visual niche a given species occupies. Nevertheless, few studies have addressed this functional readout of pattern to date and our understanding of its development has remained superficial. Here, we review recent advances in understanding the molecular cascades that control regionalization of the eye anlage, relate these findings to the development of photoreceptor patterns and discuss common and unique strategies involved in both aspects of retinal pattern formation.
Collapse
Affiliation(s)
- Dorothea Schulte
- Max Planck Institute for Brain Research, Department of Neuroanatomy, Deutschordenst. 46, D-60218 Frankfurt, Germany.
| | | |
Collapse
|
22
|
Wang JT, Kunzevitzky NJ, Dugas JC, Cameron M, Barres BA, Goldberg JL. Disease gene candidates revealed by expression profiling of retinal ganglion cell development. J Neurosci 2007; 27:8593-603. [PMID: 17687037 PMCID: PMC2885852 DOI: 10.1523/jneurosci.4488-06.2007] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
To what extent do postmitotic neurons regulate gene expression during development or after injury? We took advantage of our ability to highly purify retinal ganglion cells (RGCs) to profile their pattern of gene expression at 13 ages from embryonic day 17 through postnatal day 21. We found that a large proportion of RGC genes are regulated dramatically throughout their postmitotic development, although the genes regulated through development in vivo generally are not regulated similarly by RGCs allowed to age in vitro. Interestingly, we found that genes regulated by developing RGCs are not generally correlated with genes regulated in RGCs stimulated to regenerate their axons. We unexpectedly found three genes associated with glaucoma, optineurin, cochlin, and CYP1B1 (cytochrome P450, family 1, subfamily B, polypeptide 1), previously thought to be primarily expressed in the trabecular meshwork, which are highly expressed by RGCs and regulated through their development. We also identified several other RGC genes that are encoded by loci linked to glaucoma. The expression of glaucoma-linked genes by RGCs suggests that, at least in some cases, RGCs may be directly involved in glaucoma pathogenesis rather than indirectly involved in response to increased intraocular pressure. Consistent with this hypothesis, we found that CYP1B1 overexpression potentiates RGC survival.
Collapse
Affiliation(s)
- Jack T. Wang
- Department of Neurobiology, Stanford University School of Medicine, Stanford, California 94305, and
| | - Noelia J. Kunzevitzky
- Bascom Palmer Eye Institute and Graduate Program in Molecular Cell and Developmental Biology, Miller School of Medicine, University of Miami, Miami, Florida 33136
| | - Jason C. Dugas
- Department of Neurobiology, Stanford University School of Medicine, Stanford, California 94305, and
| | - Meghan Cameron
- Department of Neurobiology, Stanford University School of Medicine, Stanford, California 94305, and
| | - Ben A. Barres
- Department of Neurobiology, Stanford University School of Medicine, Stanford, California 94305, and
| | - Jeffrey L. Goldberg
- Department of Neurobiology, Stanford University School of Medicine, Stanford, California 94305, and
- Bascom Palmer Eye Institute and Graduate Program in Molecular Cell and Developmental Biology, Miller School of Medicine, University of Miami, Miami, Florida 33136
| |
Collapse
|
23
|
Corbo JC, Myers CA, Lawrence KA, Jadhav AP, Cepko CL. A typology of photoreceptor gene expression patterns in the mouse. Proc Natl Acad Sci U S A 2007; 104:12069-74. [PMID: 17620597 PMCID: PMC1913549 DOI: 10.1073/pnas.0705465104] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Mutations in photoreceptor-enriched genes have been implicated in dozens of human retinal diseases, yet no systematic analysis of rod and cone gene expression patterns has been carried out. In addition, although cone photoreceptor loss accounts for much of the morbidity of retinal disease, relatively few cone-specific genes are known. In this study, we carried out microarray and in situ hybridization analyses of the mouse Neural retina leucine zipper gene (Nrl) mutant, which shows an en masse conversion of rods into cones, to establish a typology of photoreceptor gene expression and to identify novel cone-specific genes. We found a total of 18 new cone-enriched genes, some of which map near uncloned retinal disease loci. Several of these genes have a dorsal-ventral (D-V) pattern of expression similar to that of short- or medium-wavelength opsins. We carried out microarray analysis of dorsal and ventral microdissected WT retina and found additional photoreceptor genes with an asymmetric distribution. Overall, we found that photoreceptor genes fall on an expression spectrum from rod-specific to cone-specific, with many showing varying degrees of rod and cone coexpression. These expression patterns can be reliably predicted from microarray data alone. Our results demonstrate definitive molecular differences between rods and cones that may underlie the physiological differences between these two classes of photoreceptors.
Collapse
Affiliation(s)
- Joseph C. Corbo
- *Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110; and
| | - Connie A. Myers
- *Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110; and
| | - Karen A. Lawrence
- *Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110; and
| | - Ashutosh P. Jadhav
- Department of Genetics and Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115
| | - Constance L. Cepko
- Department of Genetics and Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115
- To whom correspondence should be addressed. E-mail:
| |
Collapse
|
24
|
Polleux F, Ince-Dunn G, Ghosh A. Transcriptional regulation of vertebrate axon guidance and synapse formation. Nat Rev Neurosci 2007; 8:331-40. [PMID: 17453014 DOI: 10.1038/nrn2118] [Citation(s) in RCA: 146] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The establishment of functional neural connections requires the growth of axons to specific target areas and the formation of synapses with appropriate synaptic partners. Several molecules that regulate axon guidance and synapse formation have been identified in the past decade, but it is unclear how a relatively limited number of factors can specify a large number of connections. Recent evidence indicates that transcription factors make a crucial contribution to the specification of connections in the nervous system by coordinating the response of neurons to guidance molecules and neurotransmitters.
Collapse
Affiliation(s)
- Franck Polleux
- Neuroscience Center, Department of Pharmacology, Neurodevelopmental Diseases Research Center, University of North Carolina, Chapel Hill, North Carolina 27599-7250, USA
| | | | | |
Collapse
|
25
|
Halilagic A, Ribes V, Ghyselinck NB, Zile MH, Dollé P, Studer M. Retinoids control anterior and dorsal properties in the developing forebrain. Dev Biol 2007; 303:362-75. [PMID: 17184764 DOI: 10.1016/j.ydbio.2006.11.021] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2006] [Revised: 09/01/2006] [Accepted: 11/14/2006] [Indexed: 01/22/2023]
Abstract
We have previously shown that retinoic acid (RA) synthesized by the retinaldehyde dehydrogenase 2 (RALDH2) is required in forebrain development. Deficiency in RA due to inactivation of the mouse Raldh2 gene or to complete absence of retinoids in vitamin-A-deficient (VAD) quails, leads to abnormal morphogenesis of various forebrain derivatives. In this study we show that double Raldh2/Raldh3 mouse mutants have a more severe phenotype in the craniofacial region than single null mutants. In particular, the nasal processes are truncated and the eye abnormalities are exacerbated. It has been previously shown that retinoids act mainly on cell proliferation and survival in the ventral forebrain by regulating SHH and FGF8 signaling. Using the VAD quail model, which survives longer than the Raldh-deficient mouse embryos, we found that retinoids act in maintaining the correct position of anterior and dorsal boundaries in the forebrain by modulating FGF8 anteriorly and WNT signaling dorsally. Furthermore, BMP4 and FGF8 signaling are affected in the nasal region and BMP4 is ventrally expanded in the optic vesicle. At the optic cup stage, Pax6, Tbx5 and Bmp4 are ectopically expressed in the presumptive retinal pigmented epithelium (RPE), while Otx2 and Mitf are not induced, leading to a dorsal transdifferentiation of RPE to neural retina. Therefore, besides being required for survival of ventral structures, retinoids are involved in restricting anterior identity in the telencephalon and dorsal identity in the diencephalon and the retina.
Collapse
Affiliation(s)
- Aida Halilagic
- MRC Centre for Developmental Neurobiology, King's College London, Guy's Campus, London SE1 1UL, UK
| | | | | | | | | | | |
Collapse
|
26
|
Adler R, Canto-Soler MV. Molecular mechanisms of optic vesicle development: complexities, ambiguities and controversies. Dev Biol 2007; 305:1-13. [PMID: 17335797 PMCID: PMC1927083 DOI: 10.1016/j.ydbio.2007.01.045] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2006] [Revised: 01/26/2007] [Accepted: 01/30/2007] [Indexed: 12/31/2022]
Abstract
Optic vesicle formation, transformation into an optic cup and integration with neighboring tissues are essential for normal eye formation, and involve the coordinated occurrence of complex cellular and molecular events. Perhaps not surprisingly, these complex phenomena have provided fertile ground for controversial and even contradictory results and conclusions. After presenting an overview of current knowledge of optic vesicle development, we will address conceptual and methodological issues that complicate research in this field. This will be done through a review of the pertinent literature, as well as by drawing on our own experience, gathered through recent studies of both intra- and extra-cellular regulation of optic vesicle development and patterning. Finally, and without attempting to be exhaustive, we will point out some important aspects of optic vesicle development that have not yet received enough attention.
Collapse
Affiliation(s)
- Ruben Adler
- Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD 21287-9257, USA.
| | | |
Collapse
|
27
|
Shelton DN, Sandoval IT, Eisinger A, Chidester S, Ratnayake A, Ireland CM, Jones DA. Up-regulation of CYP26A1 in adenomatous polyposis coli-deficient vertebrates via a WNT-dependent mechanism: implications for intestinal cell differentiation and colon tumor development. Cancer Res 2006; 66:7571-7. [PMID: 16885356 DOI: 10.1158/0008-5472.can-06-1067] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Mutations in the adenomatous polyposis coli (APC) tumor suppressor gene seem to underlie the initiation of many colorectal carcinomas. Loss of APC function results in accumulation of beta-catenin and activation of beta-catenin/TCF-dependent transcription. Recent studies have implicated APC in controlling retinoic acid biosynthesis during normal intestinal development through a WNT-independent mechanism. Paradoxically, however, previous studies found that dietary supplementation of Apc(MIN) mice with retinoic acid failed to abrogate adenoma formation. While investigating the above finding, we found that expression of CYP26A1, a major retinoic acid catabolic enzyme, was up-regulated in Apc(MIN) mouse adenomas, human FAP adenomas, human sporadic colon carcinomas, and in the intestine of apc(mcr) mutant zebrafish embryos. Mechanistically, cyp26a1 induction following apc mutation is dependent on WNT signaling as antisense morpholino knockdown of tcf4 or injection of a dnLEF construct into apc(mcr) mutant zebrafish suppressed expression of cyp26a1 along with known WNT target genes. In addition, injection of stabilized beta-catenin or dnGSK3beta into wild-type embryos induced cyp26a1 expression. Genetic knockdown or pharmacologic inhibition of cyp26a1 in apc(mcr) mutant zebrafish embryos rescued gut differentiation defects such as expression of intestinal fatty acid-binding protein and pancreatic trypsin. These findings support a novel role for APC in balancing retinoic acid biosynthesis and catabolism through WNT-independent and WNT-dependent mechanisms.
Collapse
Affiliation(s)
- Dawne N Shelton
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, 2000 Circle of Hope, Salt Lake City, UT 84112, USA
| | | | | | | | | | | | | |
Collapse
|
28
|
Molotkov A, Molotkova N, Duester G. Retinoic acid guides eye morphogenetic movements via paracrine signaling but is unnecessary for retinal dorsoventral patterning. Development 2006; 133:1901-10. [PMID: 16611695 PMCID: PMC2833011 DOI: 10.1242/dev.02328] [Citation(s) in RCA: 170] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Retinoic acid (RA) is required for patterning of the posterior nervous system, but its role in the retina remains unclear. RA is synthesized in discrete regions of the embryonic eye by three retinaldehyde dehydrogenases (RALDHs) displaying distinct expression patterns. Overlapping functions of these enzymes have hampered genetic efforts to elucidate RA function in the eye. Here, we report Raldh1, Raldh2 and Raldh3 single, double and triple null mice exhibiting progressively less or no RA synthesis in the eye. Our genetic studies indicate that RA signaling is not required for the establishment or maintenance of dorsoventral patterning in the retina, as we observe normal expression of Tbx5 and ephrin B2 (Efnb2) dorsally, plus Vax2 and Ephb2 ventrally. Instead, RA is required for the morphogenetic movements needed to shape the developing retina and surrounding mesenchyme. At early stages, Raldh2 expressed in mesenchyme and Raldh3 expressed in the retinal pigmented epithelium generate RA that delivers an essential signal to the neural retina required for morphogenetic movements that lead to ventral invagination of the optic cup. At later stages, Raldh1 expressed in dorsal neural retina and Raldh3 expressed in ventral neural retina (plus weaker expression of each in lens/corneal ectoderm) generates RA that travels to surrounding mesenchyme, where it is needed to limit the anterior invasion of perioptic mesenchyme during the formation of corneal mesenchyme and eyelids. At all stages, RA target tissues are distinct from locations of RA synthesis, indicating that RALDHs function cell-nonautonomously to generate paracrine RA signals that guide morphogenetic movements in neighboring cells.
Collapse
|
29
|
Lupo G, Harris WA, Lewis KE. Mechanisms of ventral patterning in the vertebrate nervous system. Nat Rev Neurosci 2006; 7:103-14. [PMID: 16429120 DOI: 10.1038/nrn1843] [Citation(s) in RCA: 169] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Dorsoventral patterning of the neural tube has a crucial role in shaping the functional organization of the CNS. It is well established that hedgehog signalling plays a key role in specifying ventral cell types throughout the neuroectoderm, and major progress has been made in elucidating how hedgehog signalling works in this ventral specification. In addition, other molecular pathways, including nodal, retinoic acid and fibroblast growth factor signalling, have been identified as important molecular cues for ventral patterning of the spinal cord, telencephalon and eye. Here, we discuss recent advances in this field, highlighting the emerging interplay of these signalling pathways in the molecular specification of ventral patterning at different rostrocaudal levels of the CNS.
Collapse
Affiliation(s)
- Giuseppe Lupo
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
| | | | | |
Collapse
|
30
|
Rowan A. Mapping eye development. Nat Rev Neurosci 2006. [DOI: 10.1038/nrn1833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|