1
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Zhang X, Leavey P, Appel H, Makrides N, Blackshaw S. Molecular mechanisms controlling vertebrate retinal patterning, neurogenesis, and cell fate specification. Trends Genet 2023; 39:736-757. [PMID: 37423870 PMCID: PMC10529299 DOI: 10.1016/j.tig.2023.06.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 06/06/2023] [Accepted: 06/07/2023] [Indexed: 07/11/2023]
Abstract
This review covers recent advances in understanding the molecular mechanisms controlling neurogenesis and specification of the developing retina, with a focus on insights obtained from comparative single cell multiomic analysis. We discuss recent advances in understanding the mechanisms by which extrinsic factors trigger transcriptional changes that spatially pattern the optic cup (OC) and control the initiation and progression of retinal neurogenesis. We also discuss progress in unraveling the core evolutionarily conserved gene regulatory networks (GRNs) that specify early- and late-state retinal progenitor cells (RPCs) and neurogenic progenitors and that control the final steps in determining cell identity. Finally, we discuss findings that provide insight into regulation of species-specific aspects of retinal patterning and neurogenesis, including consideration of key outstanding questions in the field.
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Affiliation(s)
- Xin Zhang
- Department of Ophthalmology, Columbia University School of Medicine, New York, NY, USA; Department of Pathology and Cell Biology, Columbia University School of Medicine, New York, NY, USA.
| | - Patrick Leavey
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Haley Appel
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Neoklis Makrides
- Department of Ophthalmology, Columbia University School of Medicine, New York, NY, USA
| | - Seth Blackshaw
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Psychiatry and Behavioral Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Ophthalmology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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2
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Cardozo MJ, Sánchez-Bustamante E, Bovolenta P. Optic cup morphogenesis across species and related inborn human eye defects. Development 2023; 150:286775. [PMID: 36714981 PMCID: PMC10110496 DOI: 10.1242/dev.200399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The vertebrate eye is shaped as a cup, a conformation that optimizes vision and is acquired early in development through a process known as optic cup morphogenesis. Imaging living, transparent teleost embryos and mammalian stem cell-derived organoids has provided insights into the rearrangements that eye progenitors undergo to adopt such a shape. Molecular and pharmacological interference with these rearrangements has further identified the underlying molecular machineries and the physical forces involved in this morphogenetic process. In this Review, we summarize the resulting scenarios and proposed models that include common and species-specific events. We further discuss how these studies and those in environmentally adapted blind species may shed light on human inborn eye malformations that result from failures in optic cup morphogenesis, including microphthalmia, anophthalmia and coloboma.
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Affiliation(s)
- Marcos J Cardozo
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, c/ Nicolás Cabrera 1, Cantoblanco, Madrid 28049, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), c/ Nicolás Cabrera 1, Cantoblanco, Madrid 28049, Spain
| | - Elena Sánchez-Bustamante
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, c/ Nicolás Cabrera 1, Cantoblanco, Madrid 28049, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), c/ Nicolás Cabrera 1, Cantoblanco, Madrid 28049, Spain
| | - Paola Bovolenta
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, c/ Nicolás Cabrera 1, Cantoblanco, Madrid 28049, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), c/ Nicolás Cabrera 1, Cantoblanco, Madrid 28049, Spain
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3
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Li X, Gordon PJ, Gaynes JA, Fuller AW, Ringuette R, Santiago CP, Wallace V, Blackshaw S, Li P, Levine EM. Lhx2 is a progenitor-intrinsic modulator of Sonic Hedgehog signaling during early retinal neurogenesis. eLife 2022; 11:e78342. [PMID: 36459481 PMCID: PMC9718532 DOI: 10.7554/elife.78342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2022] [Accepted: 11/09/2022] [Indexed: 12/03/2022] Open
Abstract
An important question in organogenesis is how tissue-specific transcription factors interact with signaling pathways. In some cases, transcription factors define the context for how signaling pathways elicit tissue- or cell-specific responses, and in others, they influence signaling through transcriptional regulation of signaling components or accessory factors. We previously showed that during optic vesicle patterning, the Lim-homeodomain transcription factor Lhx2 has a contextual role by linking the Sonic Hedgehog (Shh) pathway to downstream targets without regulating the pathway itself. Here, we show that during early retinal neurogenesis in mice, Lhx2 is a multilevel regulator of Shh signaling. Specifically, Lhx2 acts cell autonomously to control the expression of pathway genes required for efficient activation and maintenance of signaling in retinal progenitor cells. The Shh co-receptors Cdon and Gas1 are candidate direct targets of Lhx2 that mediate pathway activation, whereas Lhx2 directly or indirectly promotes the expression of other pathway components important for activation and sustained signaling. We also provide genetic evidence suggesting that Lhx2 has a contextual role by linking the Shh pathway to downstream targets. Through these interactions, Lhx2 establishes the competence for Shh signaling in retinal progenitors and the context for the pathway to promote early retinal neurogenesis. The temporally distinct interactions between Lhx2 and the Shh pathway in retinal development illustrate how transcription factors and signaling pathways adapt to meet stage-dependent requirements of tissue formation.
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Affiliation(s)
- Xiaodong Li
- Vanderbilt Eye Institute, Vanderbilt University Medical CenterNashvilleUnited States
| | - Patrick J Gordon
- John A. Moran Eye Center, University of UtahSalt Lake CityUnited States
| | - John A Gaynes
- John A. Moran Eye Center, University of UtahSalt Lake CityUnited States
| | - Alexandra W Fuller
- Department of Cell and Developmental Biology, Vanderbilt UniversityNashvilleUnited States
| | - Randy Ringuette
- Cellular and Molecular Medicine, University of OttawaOttawaCanada
| | - Clayton P Santiago
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of MedicineBaltimoreUnited States
| | - Valerie Wallace
- Donald K. Johnson Eye Institute, Krembil Research Institute, University Health NetworkTorontoCanada
| | - Seth Blackshaw
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of MedicineBaltimoreUnited States
| | - Pulin Li
- Whitehead Institute of Biomedical Research, Department of Biology, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Edward M Levine
- Vanderbilt Eye Institute, Vanderbilt University Medical CenterNashvilleUnited States
- John A. Moran Eye Center, University of UtahSalt Lake CityUnited States
- Department of Cell and Developmental Biology, Vanderbilt UniversityNashvilleUnited States
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4
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Luo H, Luo S, Fang W, Lin Q, Chen X, Zhou X. Genomic insight into the nocturnal adaptation of the black-crowned night heron (Nycticorax nycticorax). BMC Genomics 2022; 23:683. [PMID: 36192687 PMCID: PMC9531477 DOI: 10.1186/s12864-022-08904-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 09/20/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The black-crowned night heron (Nycticorax nycticorax) is an ardeid bird successfully adapted to the nocturnal environment. Previous studies had indicated that the eyes of the night herons have evolved several specialized morphological traits favoring nocturnal vision. However, the molecular mechanisms of the nocturnal vision adaptation of night herons remained inattentions. In this study, the whole genome of N. nycticorax was sequenced and comparative analyses were performed on the vision-related and olfactory receptor (OR) genes to understand the molecular mechanisms of the visual and olfactory adaptation of night herons. RESULTS The results indicated that a number of vision genes were under positive or relaxed selection in N. nycticorax, whereas a number of other vision genes were under relaxed or intensified selection in the boat-billed heron (Cochlearius cochlearius), which suggested that the two species adapt to nocturnality with different genetic mechanisms. The different selections acting on vision genes are probably associated with the enlargement of eye size and the enhancement of visual sensitivity in night herons. The analyses on olfactory receptor (OR) genes indicated that the total number of OR genes in the genomes of N. nycticorax and C. cochlearius were about half those in the little egret (Egretta garzetta), whereas the diversity of their OR genes was not remarkably different. Additionally, the number of expressed OR genes in the transcriptomes of N. nycticorax was also fewer than that in E. garzetta. These results suggest a reduced olfactory capability in night herons compared with E. garzetta. CONCLUSIONS Our results provided evidence that several vision genes of the night herons were subjected to different natural selections, which can contribute to a better understanding of the genetic mechanisms of visual adaptions of the night heron. In addition, the finding of the reduced number of total and expressed OR genes in night herons may reflect a trade-off between olfaction and vision.
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Affiliation(s)
- Haoran Luo
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen, 361102, People's Republic of China
| | - Site Luo
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen, 361102, People's Republic of China
| | - Wenzhen Fang
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen, 361102, People's Republic of China
| | - Qingxian Lin
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen, 361102, People's Republic of China
| | - Xiaolin Chen
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen, 361102, People's Republic of China.
| | - Xiaoping Zhou
- Key Laboratory of Ministry of Education for Coastal and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen, 361102, People's Republic of China.
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Islam F, Htun S, Lai LW, Krall M, Poranki M, Martin PM, Sobreira N, Wohler ES, Yu J, Moore AT, Slavotinek AM. Exome sequencing in patients with microphthalmia, anophthalmia, and coloboma (MAC) from a consanguineous population. Clin Genet 2020; 98:499-506. [PMID: 32799327 DOI: 10.1111/cge.13830] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 08/08/2020] [Accepted: 08/10/2020] [Indexed: 12/13/2022]
Abstract
Next-generation sequencing strategies have resulted in mutation detection rates of 21% to 61% in small cohorts of patients with microphthalmia, anophthalmia and coloboma (MAC), but despite progress in identifying novel causative genes, many patients remain without a genetic diagnosis. We studied a cohort of 19 patients with MAC who were ascertained from a population with high rates of consanguinity. Using single nucleotide polymorphism (SNP) arrays and whole exome sequencing (WES), we identified one pathogenic variant in TENM3 in a patient with cataracts in addition to MAC. We also detected novel variants of unknown significance in genes that have previously been associated with MAC, including KIF26B, MICU1 and CDON, and identified variants in candidate genes for MAC from the Wnt signaling pathway, comprising LRP6, WNT2B and IQGAP1, but our findings do not prove causality. Plausible variants were not found for many of the cases, indicating that our current understanding of the pathogenesis of MAC, a highly heterogeneous group of ocular defects, remains incomplete.
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Affiliation(s)
- Farrah Islam
- Department of Ophthalmology, Al-Shifa Eye Trust Hospital, Rawalpindi, Pakistan
| | - Stephanie Htun
- Division of Genetics, Department of Pediatrics, University of California San Francisco, San Francisco, California, USA
| | - Li-Wen Lai
- Department of Pathology, University of Arizona, Tucson, Arizona, USA
| | - Max Krall
- Division of Genetics, Department of Pediatrics, University of California San Francisco, San Francisco, California, USA
| | - Menitha Poranki
- Division of Genetics, Department of Pediatrics, University of California San Francisco, San Francisco, California, USA
| | - Pierre-Marie Martin
- Institute of Human Genetics, University of California San Francisco, San Francisco, California, USA
| | - Nara Sobreira
- McKusick-Nathans Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Elizabeth S Wohler
- McKusick-Nathans Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Jingwei Yu
- Department of Laboratory Medicine, University of California San Francisco, San Francisco, California, USA
| | - Anthony T Moore
- Dept. Ophthalmology, University of California San Francisco, San Francisco, California, USA
| | - Anne M Slavotinek
- Division of Genetics, Department of Pediatrics, University of California San Francisco, San Francisco, California, USA
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6
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Hong M, Christ A, Christa A, Willnow TE, Krauss RS. Cdon mutation and fetal alcohol converge on Nodal signaling in a mouse model of holoprosencephaly. eLife 2020; 9:60351. [PMID: 32876567 PMCID: PMC7467722 DOI: 10.7554/elife.60351] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 08/10/2020] [Indexed: 02/07/2023] Open
Abstract
Holoprosencephaly (HPE), a defect in midline patterning of the forebrain and midface, arises ~1 in 250 conceptions. It is associated with predisposing mutations in the Nodal and Hedgehog (HH) pathways, with penetrance and expressivity graded by genetic and environmental modifiers, via poorly understood mechanisms. CDON is a multifunctional co-receptor, including for the HH pathway. In mice, Cdon mutation synergizes with fetal alcohol exposure, producing HPE phenotypes closely resembling those seen in humans. We report here that, unexpectedly, Nodal signaling is a major point of synergistic interaction between Cdon mutation and fetal alcohol. Window-of-sensitivity, genetic, and in vitro findings are consistent with a model whereby brief exposure of Cdon mutant embryos to ethanol during gastrulation transiently and partially inhibits Nodal pathway activity, with consequent effects on midline patterning. These results illuminate mechanisms of gene-environment interaction in a multifactorial model of a common birth defect.
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Affiliation(s)
- Mingi Hong
- Department of Cell, Developmental, and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, United States
| | - Annabel Christ
- Max-Delbruck-Center for Molecular Medicine, Berlin, Germany
| | - Anna Christa
- Max-Delbruck-Center for Molecular Medicine, Berlin, Germany
| | | | - Robert S Krauss
- Department of Cell, Developmental, and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, United States
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7
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Berkun L, Slae M, Mor-Shaked H, Koplewitz B, Eventov-Friedman S, Harel T. Homozygous variants in MAPRE2 and CDON in individual with skin folds, growth delay, retinal coloboma, and pyloric stenosis. Am J Med Genet A 2019; 179:2454-2458. [PMID: 31502381 DOI: 10.1002/ajmg.a.61355] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2019] [Revised: 07/25/2019] [Accepted: 08/25/2019] [Indexed: 01/05/2023]
Abstract
Cases with multiple molecular diagnoses are challenging to diagnose clinically, yet may be resolved by unbiased exome sequencing analysis. We report an infant with developmental delay, severe growth delay, dysmorphic features, and multiple congenital anomalies including retinal coloboma, congenital pyloric stenosis, and circumferential skin creases. Exome sequencing identified a homozygous missense variant in MAPRE2 and a homozygous stopgain (nonsense) variant in CDON. Variants in MAPRE2, encoding a regulator of microtubule dynamics, lead to congenital symmetric circumferential skin creases type 2, with associated dysmorphism, small growth parameters, and congenital cardiac and genital anomalies. Monoallelic variants in CDON, encoding a coreceptor for sonic hedgehog, have been associated with autosomal dominant pituitary stalk interruption syndrome and holoprosencephaly. Cdon-/- mice have multiple eye defects including coloboma, consistent with the observed human phenotype. Thus, the complex phenotypic presentation of the infant may potentially be attributed to a dual molecular diagnosis. Furthermore, we present CDON as a candidate gene for coloboma formation in addition to the known holoprosencephaly phenotype, and propose to expand the allelic spectrum of CDON to variants associated with autosomal recessive inheritance in addition to dominant inheritance.
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Affiliation(s)
- Lina Berkun
- Department of Pediatrics, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Mordechai Slae
- Department of Pediatrics, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Hagar Mor-Shaked
- Department of Genetic and Metabolic Diseases, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | - Benjamin Koplewitz
- Department of Medical Imaging, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
| | | | - Tamar Harel
- Department of Genetic and Metabolic Diseases, Hadassah-Hebrew University Medical Center, Jerusalem, Israel
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8
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An update on the genetics of ocular coloboma. Hum Genet 2019; 138:865-880. [PMID: 31073883 DOI: 10.1007/s00439-019-02019-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 04/19/2019] [Indexed: 01/04/2023]
Abstract
Ocular coloboma is an uncommon, but often severe, sight-threatening condition that can be identified from birth. This congenital anomaly is thought to be caused by maldevelopment of optic fissure closure during early eye morphogenesis. It has been causally linked to both inherited (genetic) and environmental influences. In particular, as a consequence of work to identify genetic causes of coloboma, new molecular pathways that control optic fissure closure have now been identified. Many more regulatory mechanisms still await better understanding to inform on the development of potential therapies for patients with this malformation. This review provides an update of known coloboma genes, the pathways they influence and how best to manage the condition. In the age of precision medicine, determining the underlying genetic cause in any given patient is of high importance.
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Abstract
Cell-to-cell communication is fundamental for embryo development and subsequent tissue homeostasis. This communication is often mediated by a small number of signaling pathways in which a secreted ligand binds to the surface of a target cell, thereby activating signal transduction. In vertebrate neural development, these signaling mechanisms are repeatedly used to obtain different and context-dependent outcomes. Part of the versatility of these communication mechanisms depends on their finely tuned regulation that controls timing, spatial localization, and duration of the signaling. The existence of secreted antagonists, which prevent ligand–receptor interaction, is an efficient mechanism to regulate some of these pathways. The Hedgehog family of signaling proteins, however, activates a pathway that is controlled largely by the positive or negative activity of membrane-bound proteins such as Cdon, Boc, Gas1, or Megalin/LRP2. In this review, we will use the development of the vertebrate retina, from its early specification to neurogenesis, to discuss whether there is an advantage to the use of such regulators, pointing to unresolved or controversial issues.
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Affiliation(s)
- Viviana Gallardo
- Centro de Biología Molecular , CSIC-UAM, Madrid, 28049, Spain.,CIBER de Enfermedades Raras (CIBERER), Madrid, 28029, Spain
| | - Paola Bovolenta
- Centro de Biología Molecular , CSIC-UAM, Madrid, 28049, Spain.,CIBER de Enfermedades Raras (CIBERER), Madrid, 28029, Spain
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10
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Genes and pathways in optic fissure closure. Semin Cell Dev Biol 2017; 91:55-65. [PMID: 29198497 DOI: 10.1016/j.semcdb.2017.10.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 08/29/2017] [Accepted: 10/10/2017] [Indexed: 12/22/2022]
Abstract
Embryonic development of the vertebrate eye begins with the formation of an optic vesicle which folds inwards to form a double-layered optic cup with a fissure on the ventral surface, known as the optic fissure. Closure of the optic fissure is essential for subsequent growth and development of the eye. A defect in this process can leave a gap in the iris, retina or optic nerve, known as a coloboma, which can lead to severe visual impairment. This review brings together current information about genes and pathways regulating fissure closure from human coloboma patients and animal models. It focuses especially on current understanding of the morphological changes and processes of epithelial remodelling occurring at the fissure margins.
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Kahn BM, Corman TS, Lovelace K, Hong M, Krauss RS, Epstein DJ. Prenatal ethanol exposure in mice phenocopies Cdon mutation by impeding Shh function in the etiology of optic nerve hypoplasia. Dis Model Mech 2016; 10:29-37. [PMID: 27935818 PMCID: PMC5278523 DOI: 10.1242/dmm.026195] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 11/16/2016] [Indexed: 01/01/2023] Open
Abstract
Septo-optic dysplasia (SOD) is a congenital disorder characterized by optic nerve, pituitary and midline brain malformations. The clinical presentation of SOD is highly variable with a poorly understood etiology. The majority of SOD cases are sporadic, but in rare instances inherited mutations have been identified in a small number of transcription factors, some of which regulate the expression of Sonic hedgehog (Shh) during mouse forebrain development. SOD is also associated with young maternal age, suggesting that environmental factors, including alcohol consumption at early stages of pregnancy, might increase the risk of developing this condition. Here, we address the hypothesis that SOD is a multifactorial disorder stemming from interactions between mutations in Shh pathway genes and prenatal ethanol exposure. Mouse embryos with mutations in the Shh co-receptor, Cdon, were treated in utero with ethanol or saline at embryonic day 8 (E8.0) and evaluated for optic nerve hypoplasia (ONH), a prominent feature of SOD. We show that both Cdon-/- mutation and prenatal ethanol exposure independently cause ONH through a similar pathogenic mechanism that involves selective inhibition of Shh signaling in retinal progenitor cells, resulting in their premature cell-cycle arrest, precocious differentiation and failure to properly extend axons to the optic nerve. The ONH phenotype was not exacerbated in Cdon-/- embryos treated with ethanol, suggesting that an intact Shh signaling pathway is required for ethanol to exert its teratogenic effects. These results support a model whereby mutations in Cdon and prenatal ethanol exposure increase SOD risk through spatiotemporal perturbations in Shh signaling activity.
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Affiliation(s)
- Benjamin M Kahn
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Tanya S Corman
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Korah Lovelace
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Mingi Hong
- Department of Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Robert S Krauss
- Department of Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Douglas J Epstein
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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12
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A Shh coreceptor Cdo is required for efficient cardiomyogenesis of pluripotent stem cells. J Mol Cell Cardiol 2016; 93:57-66. [PMID: 26906632 DOI: 10.1016/j.yjmcc.2016.01.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 01/13/2016] [Indexed: 11/20/2022]
Abstract
Sonic hedgehog (Shh) signaling plays an important role for early heart development, such as heart looping and cardiomyogenesis of pluripotent stem cells. A multifunctional receptor Cdo functions as a Shh coreceptor together with Boc and Gas1 to activate Shh signaling and these coreceptors seem to play compensatory roles in early heart development. Thus in this study, we examined the role of Cdo in cardiomyogenesis by utilizing an in vitro differentiation of pluripotent stem cells. Here we show that Cdo is required for efficient cardiomyogenesis of pluripotent stem cells by activation of Shh signaling. Cdo is induced concurrently with Shh signaling activation upon induction of cardiomyogenesis of P19 embryonal carcinoma (EC) cells. Cdo-depleted P19 EC and Cdo(-/-) mouse embryonic stem (ES) cells display decreased expression of key cardiac regulators, including Gata4, Nkx2.5 and Mef2c and this decrease coincides with reduced Shh signaling activities. Furthermore Cdo deficiency causes a stark reduction in formation of mature contractile cardiomyocytes. This defect in cardiomyogenesis is overcome by reactivation of Shh signaling at the early specification stage of cardiomyogenesis. The Shh agonist treatment restores differentiation capacities of Cdo-deficient ES cells into contractile cardiomyocytes by recovering both the expression of early cardiac regulators and structural genes such as cardiac troponin T and Connexin 43. Therefore Cdo is required for efficient cardiomyogenesis of pluripotent stem cells and an excellent target to improve the differentiation potential of stem cells for generation of transplantable cells to treat cardiomyopathies.
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13
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Xavier GM, Seppala M, Barrell W, Birjandi AA, Geoghegan F, Cobourne MT. Hedgehog receptor function during craniofacial development. Dev Biol 2016; 415:198-215. [PMID: 26875496 DOI: 10.1016/j.ydbio.2016.02.009] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 02/09/2016] [Accepted: 02/10/2016] [Indexed: 01/20/2023]
Abstract
The Hedgehog signalling pathway plays a fundamental role in orchestrating normal craniofacial development in vertebrates. In particular, Sonic hedgehog (Shh) is produced in three key domains during the early formation of the head; neuroectoderm of the ventral forebrain, facial ectoderm and the pharyngeal endoderm; with signal transduction evident in both ectodermal and mesenchymal tissue compartments. Shh signalling from the prechordal plate and ventral midline of the diencephalon is required for appropriate division of the eyefield and forebrain, with mutation in a number of pathway components associated with Holoprosencephaly, a clinically heterogeneous developmental defect characterized by a failure of the early forebrain vesicle to divide into distinct halves. In addition, signalling from the pharyngeal endoderm and facial ectoderm plays an essential role during development of the face, influencing cranial neural crest cells that migrate into the early facial processes. In recent years, the complexity of Shh signalling has been highlighted by the identification of multiple novel proteins that are involved in regulating both the release and reception of this protein. Here, we review the contributions of Shh signalling during early craniofacial development, focusing on Hedgehog receptor function and describing the consequences of disruption for inherited anomalies of this region in both mouse models and human populations.
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Affiliation(s)
- Guilherme M Xavier
- Department of Craniofacial Development and Stem Cell Biology, King's College London Dental Institute, Floor 27, Guy's Hospital, London SE1 9RT, UK; Department of Orthodontics, King's College London Dental Institute, Floor 27, Guy's Hospital, London SE1 9RT, UK
| | - Maisa Seppala
- Department of Craniofacial Development and Stem Cell Biology, King's College London Dental Institute, Floor 27, Guy's Hospital, London SE1 9RT, UK; Department of Orthodontics, King's College London Dental Institute, Floor 27, Guy's Hospital, London SE1 9RT, UK
| | - William Barrell
- Department of Craniofacial Development and Stem Cell Biology, King's College London Dental Institute, Floor 27, Guy's Hospital, London SE1 9RT, UK
| | - Anahid A Birjandi
- Department of Craniofacial Development and Stem Cell Biology, King's College London Dental Institute, Floor 27, Guy's Hospital, London SE1 9RT, UK
| | - Finn Geoghegan
- Department of Craniofacial Development and Stem Cell Biology, King's College London Dental Institute, Floor 27, Guy's Hospital, London SE1 9RT, UK
| | - Martyn T Cobourne
- Department of Craniofacial Development and Stem Cell Biology, King's College London Dental Institute, Floor 27, Guy's Hospital, London SE1 9RT, UK; Department of Orthodontics, King's College London Dental Institute, Floor 27, Guy's Hospital, London SE1 9RT, UK.
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Dash S, Dang CA, Beebe DC, Lachke SA. Deficiency of the RNA binding protein caprin2 causes lens defects and features of Peters anomaly. Dev Dyn 2015; 244:1313-27. [PMID: 26177727 DOI: 10.1002/dvdy.24303] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 06/18/2015] [Accepted: 07/02/2015] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND It was recently demonstrated that deficiency of a conserved RNA binding protein (RBP) and RNA granule (RG) component Tdrd7 causes ocular defects including cataracts in human, mouse and chicken, indicating the importance of posttranscriptional regulation in eye development. Here we investigated the function of a second conserved RBP/RG component Caprin2 that is identified by the eye gene discovery tool iSyTE. RESULTS In situ hybridization, Western blotting and immunostaining confirmed highly enriched expression of Caprin2 mRNA and protein in mouse embryonic and postnatal lens. To gain insight into its function, lens-specific Caprin2 conditional knockout (cKO) mouse mutants were generated using a lens-Cre deleter line Pax6GFPCre. Phenotypic analysis of Caprin2(cKO/cKO) mutants revealed distinct eye defects at variable penetrance. Wheat germ agglutinin staining and scanning electron microscopy demonstrated that Caprin2(cKO/cKO) mutants have an abnormally compact lens nucleus, which is the core of the lens comprised of centrally located terminally differentiated fiber cells. Additionally, Caprin2(cKO/cKO) mutants also exhibited at 8% penetrance a developmental defect that resembles a human condition called Peters anomaly, wherein the lens and the cornea remain attached by a persistent stalk. CONCLUSIONS These data suggest that a conserved RBP Caprin2 functions in distinct morphological events in mammalian eye development.
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Affiliation(s)
- Soma Dash
- Department of Biological Sciences, University of Delaware, Newark, Delaware
| | - Christine A Dang
- Department of Biological Sciences, University of Delaware, Newark, Delaware
| | - David C Beebe
- Department of Ophthalmology and Visual Sciences, Washington University, St. Louis, Missouri
| | - Salil A Lachke
- Department of Biological Sciences, University of Delaware, Newark, Delaware.,Center for Bioinformatics & Computational Biology, University of Delaware, Newark, Delaware
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15
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Tao C, Zhang X. Development of astrocytes in the vertebrate eye. Dev Dyn 2014; 243:1501-10. [PMID: 25236977 DOI: 10.1002/dvdy.24190] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 08/22/2014] [Accepted: 09/12/2014] [Indexed: 02/04/2023] Open
Abstract
Astrocytes represent the earliest glial population in the embryonic optic nerve, contributing critically to retinal angiogenesis and formation of brain-retinal-barrier. Despite of many developmental and clinical implications of astrocytes, answers to some of the most fundamental questions of this unique type of glial cells remain elusive. This review provides an overview of the current knowledge about the origination, proliferation, and differentiation of astrocytes, their journey from the optic nerve toward the neuroretina, and their involvement in physiological and pathological development of the visual system.
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Affiliation(s)
- Chenqi Tao
- Stark Neuroscience Institute, Indiana University School of Medicine, Indianapolis, Indiana; Departments of Ophthalmology, Pathology, and Cell Biology, Columbia University, New York, New York
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16
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Choi JJY, Ting CT, Trogrlic L, Milevski SV, Familari M, Martinez G, de Iongh RU. A role for smoothened during murine lens and cornea development. PLoS One 2014; 9:e108037. [PMID: 25268479 PMCID: PMC4182430 DOI: 10.1371/journal.pone.0108037] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 08/25/2014] [Indexed: 01/07/2023] Open
Abstract
Various studies suggest that Hedgehog (Hh) signalling plays roles in human and zebrafish ocular development. Recent studies (Kerr et al., Invest Ophthalmol Vis Sci. 2012; 53, 3316–30) showed that conditionally activating Hh signals promotes murine lens epithelial cell proliferation and disrupts fibre differentiation. In this study we examined the expression of the Hh pathway and the requirement for the Smoothened gene in murine lens development. Expression of Hh pathway components in developing lens was examined by RT-PCR, immunofluorescence and in situ hybridisation. The requirement of Smo in lens development was determined by conditional loss-of-function mutations, using LeCre and MLR10 Cre transgenic mice. The phenotype of mutant mice was examined by immunofluorescence for various markers of cell cycle, lens and cornea differentiation. Hh pathway components (Ptch1, Smo, Gli2, Gli3) were detected in lens epithelium from E12.5. Gli2 was particularly localised to mitotic nuclei and, at E13.5, Gli3 exhibited a shift from cytosol to nucleus, suggesting distinct roles for these transcription factors. Conditional deletion of Smo, from ∼E12.5 (MLR10 Cre) did not affect ocular development, whereas deletion from ∼E9.5 (LeCre) resulted in lens and corneal defects from E14.5. Mutant lenses were smaller and showed normal expression of p57Kip2, c-Maf, E-cadherin and Pax6, reduced expression of FoxE3 and Ptch1 and decreased nuclear Hes1. There was normal G1-S phase but decreased G2-M phase transition at E16.5 and epithelial cell death from E14.5-E16.5. Mutant corneas were thicker due to aberrant migration of Nrp2+ cells from the extraocular mesenchyme, resulting in delayed corneal endothelial but normal epithelial differentiation. These results indicate the Hh pathway is required during a discrete period (E9.5–E12.5) in lens development to regulate lens epithelial cell proliferation, survival and FoxE3 expression. Defective corneal development occurs secondary to defects in lens and appears to be due to defective migration of peri-ocular Nrp2+ neural crest/mesenchymal cells.
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MESH Headings
- Animals
- Animals, Newborn
- Cell Cycle
- Cell Movement
- Cornea/growth & development
- Cornea/metabolism
- Cornea/pathology
- Embryo, Mammalian
- Endothelial Cells/metabolism
- Endothelial Cells/pathology
- Epithelial Cells/metabolism
- Epithelial Cells/pathology
- Forkhead Transcription Factors/genetics
- Forkhead Transcription Factors/metabolism
- Gene Expression Regulation, Developmental
- Integrases/genetics
- Integrases/metabolism
- Kruppel-Like Transcription Factors/genetics
- Kruppel-Like Transcription Factors/metabolism
- Lens, Crystalline/growth & development
- Lens, Crystalline/metabolism
- Lens, Crystalline/pathology
- Membrane Proteins
- Mesenchymal Stem Cells/metabolism
- Mesenchymal Stem Cells/pathology
- Mice
- Mice, Transgenic
- Morphogenesis
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/metabolism
- Neuropilin-2/genetics
- Neuropilin-2/metabolism
- Patched Receptors
- Patched-1 Receptor
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/metabolism
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Signal Transduction
- Smoothened Receptor
- Zebrafish Proteins
- Zinc Finger Protein Gli2
- Zinc Finger Protein Gli3
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Affiliation(s)
- Janet J. Y. Choi
- Ocular Development Laboratory, Anatomy & Neuroscience, University of Melbourne, Parkville, Australia
| | - Chao-Tung Ting
- Ocular Development Laboratory, Anatomy & Neuroscience, University of Melbourne, Parkville, Australia
| | - Lidia Trogrlic
- Ocular Development Laboratory, Anatomy & Neuroscience, University of Melbourne, Parkville, Australia
| | - Stefan V. Milevski
- Ocular Development Laboratory, Anatomy & Neuroscience, University of Melbourne, Parkville, Australia
| | - Mary Familari
- Department of Zoology, University of Melbourne, Parkville, Australia
| | - Gemma Martinez
- Ocular Development Laboratory, Anatomy & Neuroscience, University of Melbourne, Parkville, Australia
| | - Robb U de Iongh
- Ocular Development Laboratory, Anatomy & Neuroscience, University of Melbourne, Parkville, Australia
- * E-mail:
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17
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Cdon acts as a Hedgehog decoy receptor during proximal-distal patterning of the optic vesicle. Nat Commun 2014; 5:4272. [PMID: 25001599 PMCID: PMC4102123 DOI: 10.1038/ncomms5272] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Accepted: 05/26/2014] [Indexed: 02/06/2023] Open
Abstract
Patterning of the vertebrate optic vesicle into proximal/optic stalk and distal/neural retina involves midline-derived Hedgehog (Hh) signalling, which promotes stalk specification. In the absence of Hh signalling, the stalks are not specified, causing cyclopia. Recent studies showed that the cell adhesion molecule Cdon forms a heteromeric complex with the Hh receptor Patched 1 (Ptc1). This receptor complex binds Hh and enhances signalling activation, indicating that Cdon positively regulates the pathway. Here we show that in the developing zebrafish and chick optic vesicle, in which cdon and ptc1 are expressed with a complementary pattern, Cdon acts as a negative Hh signalling regulator. Cdon predominantly localizes to the basolateral side of neuroepithelial cells, promotes the enlargement of the neuroepithelial basal end-foot and traps Hh protein, thereby limiting its dispersion. This Ptc-independent function protects the retinal primordium from Hh activity, defines the stalk/retina boundary and thus the correct proximo-distal patterning of the eye. The Drosophila homologue of the vertebrate cell surface glycoprotein Cdon binds Hedgehog ligand and thereby prevents its diffusion. Here, the authors provide evidence for a similar mechanism during vertebrate optic vesicle patterning, where Cdon acts as a negative regulator of Hedgehog signalling to define the boundary between the optic stalk and the retina.
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18
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Cdon and Boc: Two transmembrane proteins implicated in cell-cell communication. Int J Biochem Cell Biol 2012; 44:698-702. [PMID: 22326621 DOI: 10.1016/j.biocel.2012.01.019] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Revised: 01/20/2012] [Accepted: 01/27/2012] [Indexed: 11/23/2022]
Abstract
Cdon and Boc, and their Drosophila homologues Ihog and Boi, are evolutionary conserved transmembrane glycoproteins belonging to a subgroup of the Immunoglobulin superfamily of cell adhesion molecules (CAMs). Initially isolated in vertebrates as CAMs that link cadherin function with MAPK signaling in myoblast differentiation, they have thereafter been shown to act as essential receptors for the Hedgehog (Hh) family of secreted proteins. They associate with both ligand and other Hh receptor components, including Ptch and Gas1, thus forming homo- and heteromeric complexes. In Drosophila, they are also involved in ligand processing and release from Hh producing cells. Cdon/Boc and Ihog/Boi can substitute one another and play redundant functions is some contexts. In addition, Boc, but not Cdon, mediates axon guidance information provided by Hh in specific neuronal populations, whereas mutations in the CDON cause holoprosencephaly, a human congenital anomaly defined by forebrain midline defects prominently associated with diminished Hh pathway activity.
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Murdoch JN, Copp AJ. The relationship between sonic Hedgehog signaling, cilia, and neural tube defects. BIRTH DEFECTS RESEARCH. PART A, CLINICAL AND MOLECULAR TERATOLOGY 2010; 88:633-52. [PMID: 20544799 PMCID: PMC3635124 DOI: 10.1002/bdra.20686] [Citation(s) in RCA: 144] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The Hedgehog signaling pathway is essential for many aspects of normal embryonic development, including formation and patterning of the neural tube. Absence of the sonic hedgehog (shh) ligand is associated with the midline defect holoprosencephaly, whereas increased Shh signaling is associated with exencephaly and spina bifida. To complicate this apparently simple relationship, mutation of proteins required for function of cilia often leads to impaired Shh signaling and to disruption of neural tube closure. In this article, we review the literature on Shh pathway mutants and discuss the relationship between Shh signaling, cilia, and neural tube defects.
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Affiliation(s)
- Jennifer N Murdoch
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham, Surrey, UK.
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20
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Erratum. FEBS J 2009. [DOI: 10.1111/j.1742-4658.2009.07456.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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