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Hines MA, Taneyhill LA. Elp1 function in placode-derived neurons is critical for proper trigeminal ganglion development. Dev Dyn 2024. [PMID: 39381860 DOI: 10.1002/dvdy.749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2024] [Revised: 09/06/2024] [Accepted: 09/14/2024] [Indexed: 10/10/2024] Open
Abstract
BACKGROUND The trigeminal nerve is the largest cranial nerve and functions in somatosensation. Cell bodies of this nerve are positioned in the trigeminal ganglion, which arises from the coalescence of neural crest and placode cells. While this dual cellular origin has been known for decades, the molecular mechanisms controlling trigeminal ganglion development remain obscure. We performed RNA sequencing on the forming chick trigeminal ganglion and identified Elongator acetyltransferase complex subunit 1 (Elp1) for further study. Mutations in ELP1 cause familial dysautonomia (FD), a fatal disorder characterized by the presence of smaller trigeminal nerves and sensory deficits. While Elp1 has established roles in neurogenesis, its function in placode cells during trigeminal gangliogenesis has not been investigated. RESULTS To this end, we used morpholinos to deplete Elp1 from chick trigeminal placode cells. Elp1 knockdown decreased trigeminal ganglion size and led to aberrant innervation of the eye by placode-derived neurons. Trigeminal nerve branches also appeared to exhibit reduced axon outgrowth to target tissues. CONCLUSIONS These findings reveal a new role for Elp1 in placode-derived neurons during chick trigeminal ganglion development. These results have potential high significance to provide new insights into trigeminal ganglion development and the etiology of FD.
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Affiliation(s)
- Margaret A Hines
- Department of Animal and Avian Sciences, University of Maryland, College Park, Maryland, USA
| | - Lisa A Taneyhill
- Department of Animal and Avian Sciences, University of Maryland, College Park, Maryland, USA
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André M, Dinvaut S, Castellani V, Falk J. 3D exploration of gene expression in chicken embryos through combined RNA fluorescence in situ hybridization, immunofluorescence, and clearing. BMC Biol 2024; 22:131. [PMID: 38831263 PMCID: PMC11149291 DOI: 10.1186/s12915-024-01922-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 05/16/2024] [Indexed: 06/05/2024] Open
Abstract
BACKGROUND Fine characterization of gene expression patterns is crucial to understand many aspects of embryonic development. The chicken embryo is a well-established and valuable animal model for developmental biology. The period spanning from the third to sixth embryonic days (E3 to E6) is critical for many organ developments. Hybridization chain reaction RNA fluorescent in situ hybridization (HCR RNA-FISH) enables multiplex RNA detection in thick samples including embryos of various animal models. However, its use is limited by tissue opacity. RESULTS We optimized HCR RNA-FISH protocol to efficiently label RNAs in whole mount chicken embryos from E3.5 to E5.5 and adapted it to ethyl cinnamate (ECi) tissue clearing. We show that light sheet imaging of HCR RNA-FISH after ECi clearing allows RNA expression analysis within embryonic tissues with good sensitivity and spatial resolution. Finally, whole mount immunofluorescence can be performed after HCR RNA-FISH enabling as exemplified to assay complex spatial relationships between axons and their environment or to monitor GFP electroporated neurons. CONCLUSIONS We could extend the use of HCR RNA-FISH to older chick embryos by optimizing HCR RNA-FISH and combining it with tissue clearing and 3D imaging. The integration of immunostaining makes possible to combine gene expression with classical cell markers, to correlate expressions with morphological differentiation and to depict gene expressions in gain or loss of function contexts. Altogether, this combined procedure further extends the potential of HCR RNA-FISH technique for chicken embryology.
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Affiliation(s)
- Maëlys André
- MeLiS, CNRS UMR 5284 - INSERM U1314, Université Claude Bernard Lyon 1, 8 avenue Rockefeller, 69008, Lyon, France.
| | - Sarah Dinvaut
- MeLiS, CNRS UMR 5284 - INSERM U1314, Université Claude Bernard Lyon 1, 8 avenue Rockefeller, 69008, Lyon, France
| | - Valérie Castellani
- MeLiS, CNRS UMR 5284 - INSERM U1314, Université Claude Bernard Lyon 1, 8 avenue Rockefeller, 69008, Lyon, France
| | - Julien Falk
- MeLiS, CNRS UMR 5284 - INSERM U1314, Université Claude Bernard Lyon 1, 8 avenue Rockefeller, 69008, Lyon, France.
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3
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Isabella AJ, Moens CB. Development and regeneration of the vagus nerve. Semin Cell Dev Biol 2024; 156:219-227. [PMID: 37537116 PMCID: PMC10830892 DOI: 10.1016/j.semcdb.2023.07.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Revised: 07/13/2023] [Accepted: 07/20/2023] [Indexed: 08/05/2023]
Abstract
The vagus nerve, with its myriad constituent axon branches and innervation targets, has long been a model of anatomical complexity in the nervous system. The branched architecture of the vagus nerve is now appreciated to be highly organized around the topographic and/or molecular identities of the neurons that innervate each target tissue. However, we are only just beginning to understand the developmental mechanisms by which heterogeneous vagus neuron identity is specified, patterned, and used to guide the axons of particular neurons to particular targets. Here, we summarize our current understanding of the complex topographic and molecular organization of the vagus nerve, the developmental basis of neuron specification and patterned axon guidance that supports this organization, and the regenerative mechanisms that promote, or inhibit, the restoration of vagus nerve organization after nerve damage. Finally, we highlight key unanswered questions in these areas and discuss potential strategies to address these questions.
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Affiliation(s)
- Adam J Isabella
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Cecilia B Moens
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA.
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4
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McGarvey LP, Clarke R, Lundy FT. Cough sensors from dental pulp. Pulm Pharmacol Ther 2017; 47:16-20. [PMID: 28782711 DOI: 10.1016/j.pupt.2017.08.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 08/02/2017] [Accepted: 08/03/2017] [Indexed: 10/19/2022]
Abstract
Mechanisms which alter sensory neural activity, in particular those rendering nerves hyper-responsive have been implicated in the pathophysiology of common clinical syndromes including chronic cough, itch and pain. However, experimental study of human sensory neurons is challenging because the cell bodies of peripheral neurons are housed in neuronal ganglia which are not accessible using peripheral biopsy techniques. While important advances have been made from studies conducted in animal models, there are interspecies differences. There is a need for development of a new generation of in vitro neuronal models based on human biology. In this article the propensity for human dental pulp stem cells to differentiate towards a neuronal phenotype and the potential of such a model to study altered sensory neural function will be discussed.
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Affiliation(s)
- Lorcan P McGarvey
- Centre for Experimental Medicine, Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University, Belfast, Northern Ireland, United Kingdom.
| | - Rebecca Clarke
- Centre for Experimental Medicine, Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University, Belfast, Northern Ireland, United Kingdom
| | - Fionnuala T Lundy
- Centre for Experimental Medicine, Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University, Belfast, Northern Ireland, United Kingdom
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5
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Lipovsek M, Ledderose J, Butts T, Lafont T, Kiecker C, Wizenmann A, Graham A. The emergence of mesencephalic trigeminal neurons. Neural Dev 2017. [PMID: 28637511 PMCID: PMC5480199 DOI: 10.1186/s13064-017-0088-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Background The cells of the mesencephalic trigeminal nucleus (MTN) are the proprioceptive sensory neurons that innervate the jaw closing muscles. These cells differentiate close to the two key signalling centres that influence the dorsal midbrain, the isthmus, which mediates its effects via FGF and WNT signalling and the roof plate, which is a major source of BMP signalling as well as WNT signalling. Methods In this study, we have set out to analyse the importance of FGF, WNT and BMP signalling for the development of the MTN. We have employed pharmacological inhibitors of these pathways in explant cultures as well as utilising the electroporation of inhibitory constructs in vivo in the chick embryo. Results We find that interfering with either FGF or WNT signalling has pronounced effects on MTN development whilst abrogation of BMP signalling has no effect. We show that treatment of explants with either FGF or WNT antagonists results in the generation of fewer MTN neurons and affects MTN axon extension and that inhibition of both these pathways has an additive effect. To complement these studies, we have used in vivo electroporation to inhibit BMP, FGF and WNT signalling within dorsal midbrain cells prior to, and during, their differentiation as MTN neurons. Again, we find that inhibition of BMP signalling has no effect on the development of MTN neurons. We additionally find that cells electroporated with inhibitory constructs for either FGF or WNT signalling can differentiate as MTN neurons suggesting that these pathways are not required cell intrinsically for the emergence of these neurons. Indeed, we also show that explants of dorsal mesencephalon lacking both the isthmus and roof plate can generate MTN neurons. However, we did find that inhibiting FGF or WNT signalling had consequences for MTN differentiation. Conclusions Our results suggest that the emergence of MTN neurons is an intrinsic property of the dorsal mesencephalon of gnathostomes, and that this population undergoes expansion, and maturation, along with the rest of the dorsal midbrain under the influence of FGF and WNT signalling.
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Affiliation(s)
- Marcela Lipovsek
- Centre for Developmental Neurobiology, Kings College London, London, SE1 1UL, UK
| | - Julia Ledderose
- Institute of Clinical Anatomy and Cell Analysis, Department of Anatomy, University of Tübingen, Oesterbergstrasse 3, 72074, Tuebingen, Germany.,Universitätsmedizin Berlin, NeuroCure - Institute of Biochemistry, ChariteCrossOver, Virchowweg, 610117, Berlin, Germany
| | - Thomas Butts
- Centre for Developmental Neurobiology, Kings College London, London, SE1 1UL, UK.,School of Life Sciences, University of Liverpool, Liverpool, L69 3BX, UK
| | - Tanguy Lafont
- Centre for Developmental Neurobiology, Kings College London, London, SE1 1UL, UK
| | - Clemens Kiecker
- Centre for Developmental Neurobiology, Kings College London, London, SE1 1UL, UK
| | - Andrea Wizenmann
- Institute of Clinical Anatomy and Cell Analysis, Department of Anatomy, University of Tübingen, Oesterbergstrasse 3, 72074, Tuebingen, Germany
| | - Anthony Graham
- Centre for Developmental Neurobiology, Kings College London, London, SE1 1UL, UK.
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6
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Takai R, Ohta T. A commentary on de novo MEIS2 mutation causes syndromic developmental delay with persistent gastro-esophageal reflux. J Hum Genet 2016; 61:773-4. [PMID: 27383655 DOI: 10.1038/jhg.2016.81] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Rie Takai
- The Research Institute of Personalized Health Sciences, Health Sciences University of Hokkaido, Hokkaido, Japan
| | - Tohru Ohta
- The Research Institute of Personalized Health Sciences, Health Sciences University of Hokkaido, Hokkaido, Japan
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7
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Patthey C, Clifford H, Haerty W, Ponting CP, Shimeld SM, Begbie J. Identification of molecular signatures specific for distinct cranial sensory ganglia in the developing chick. Neural Dev 2016; 11:3. [PMID: 26819088 PMCID: PMC4730756 DOI: 10.1186/s13064-016-0057-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 01/08/2016] [Indexed: 11/22/2022] Open
Abstract
Background The cranial sensory ganglia represent populations of neurons with distinct functions, or sensory modalities. The production of individual ganglia from distinct neurogenic placodes with different developmental pathways provides a powerful model to investigate the acquisition of specific sensory modalities. To date there is a limited range of gene markers available to examine the molecular pathways underlying this process. Results Transcriptional profiles were generated for populations of differentiated neurons purified from distinct cranial sensory ganglia using microdissection in embryonic chicken followed by FAC-sorting and RNAseq. Whole transcriptome analysis confirmed the division into somato- versus viscerosensory neurons, with additional evidence for subdivision of the somatic class into general and special somatosensory neurons. Cross-comparison of distinct ganglia transcriptomes identified a total of 134 markers, 113 of which are novel, which can be used to distinguish trigeminal, vestibulo-acoustic and epibranchial neuronal populations. In situ hybridisation analysis provided validation for 20/26 tested markers, and showed related expression in the target region of the hindbrain in many cases. Conclusions One hundred thirty-four high-confidence markers have been identified for placode-derived cranial sensory ganglia which can now be used to address the acquisition of specific cranial sensory modalities. Electronic supplementary material The online version of this article (doi:10.1186/s13064-016-0057-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Cedric Patthey
- Department of Zoology, University of Oxford, Oxford, UK. .,Umeå Center for Molecular Medicine, Umeå University, Umeå, Sweden.
| | - Harry Clifford
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK. .,MRC Functional Genomics, University of Oxford, Oxford, UK.
| | - Wilfried Haerty
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK. .,MRC Functional Genomics, University of Oxford, Oxford, UK.
| | - Chris P Ponting
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK. .,MRC Functional Genomics, University of Oxford, Oxford, UK.
| | | | - Jo Begbie
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
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8
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Smith AC, Fleenor SJ, Begbie J. Changes in gene expression and cell shape characterise stages of epibranchial placode-derived neuron maturation in the chick. J Anat 2015; 227:89-102. [PMID: 26076761 DOI: 10.1111/joa.12333] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/29/2015] [Indexed: 11/29/2022] Open
Abstract
Sensory neurons in the head are largely generated from neurogenic placodes. Previous studies have revealed early events in placode development; however, the process of maturation has not been studied. In this study, it has been shown that placodal neurogenesis follows a sequential progression with distinct stages defined by expression of specific markers. These markers highlight domains of maturation within the stream of migratory neuroblasts that extend between the placode and the neural tube. Commitment to neurogenesis occurs in the apical placode, with the newborn neuroblasts delaminating basally and entering a transition zone. The neuroblasts migrate through the transition zone, differentiating further and becoming post-mitotic as they approach the ganglionic anlage. It has further been demonstrated that this progression from the transition zone to the ganglionic anlage is accompanied by a switch from multipolar to bipolar cell morphology. This sequential progression parallels events observed elsewhere in the nervous system, but here the stages are distinct and anatomically segregated. It is proposed that placodal neurogenesis provides a tractable system to examine the transition between states in neurogenesis.
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Affiliation(s)
- Alexandra C Smith
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Stephen J Fleenor
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
| | - Jo Begbie
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
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9
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Murashima A, Akita H, Okazawa M, Kishigami S, Nakagata N, Nishinakamura R, Yamada G. Midline-derived Shh regulates mesonephric tubule formation through the paraxial mesoderm. Dev Biol 2013; 386:216-26. [PMID: 24370450 DOI: 10.1016/j.ydbio.2013.12.026] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 12/13/2013] [Accepted: 12/17/2013] [Indexed: 12/27/2022]
Abstract
During organogenesis, Sonic hedgehog (Shh) possesses dual functions: Shh emanating from midline structures regulates the positioning of bilateral structures at early stages, whereas organ-specific Shh locally regulates organ morphogenesis at later stages. The mesonephros is a transient embryonic kidney in amniote, whereas it becomes definitive adult kidney in some anamniotes. Thus, elucidating the regulation of mesonephros formation has important implications for our understanding of kidney development and evolution. In Shh knockout (KO) mutant mice, the mesonephros was displaced towards the midline and ectopic mesonephric tubules (MTs) were present in the caudal mesonephros. Mesonephros-specific ablation of Shh in Hoxb7-Cre;Shh(flox/-) and Sall1(CreERT2/+);Shh(flox/-) mice embryos indicated that Shh expressed in the mesonephros was not required for either the development of the mesonephros or the differentiation of the male reproductive tract. Moreover, stage-specific ablation of Shh in Shh(CreERT2/flox) mice showed that notochord- and/or floor plate-derived Shh were essential for the regulation of the number and position of MTs. Lineage analysis of hedgehog (Hh)-responsive cells, and analysis of gene expression in Shh KO embryos suggested that Shh regulated nephrogenic gene expression indirectly, possibly through effects on the paraxial mesoderm. These data demonstrate the essential role of midline-derived Shh in local tissue morphogenesis and differentiation.
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Affiliation(s)
- Aki Murashima
- Department of Developmental Genetics, Institute of Advanced Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama 641-8509, Wakayama, Japan
| | - Hiroki Akita
- Department of Developmental Genetics, Institute of Advanced Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama 641-8509, Wakayama, Japan; Faculty of Biology-Oriented Science and Technology, Kinki University, Kinokawa 649-6493, Wakayama, Japan
| | - Mika Okazawa
- Department of Developmental Genetics, Institute of Advanced Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama 641-8509, Wakayama, Japan; Department of Obstetrics and Gynecology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita 565-0871, Osaka, Japan
| | - Satoshi Kishigami
- Faculty of Biology-Oriented Science and Technology, Kinki University, Kinokawa 649-6493, Wakayama, Japan
| | - Naomi Nakagata
- Division of Reproductive Engineering, Center for Animal Resources and Development, Kumamoto University, 2-2-1 Honjo, Kumamoto 860-0811, Kumamoto, Japan
| | - Ryuichi Nishinakamura
- Department of Kidney Development, Institute of Molecular Embryology and Genetics, Kumamoto University, 2-2-1 Honjo, Kumamoto 860-0811, Kumamoto, Japan
| | - Gen Yamada
- Department of Developmental Genetics, Institute of Advanced Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama 641-8509, Wakayama, Japan.
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10
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Freter S, Fleenor SJ, Freter R, Liu KJ, Begbie J. Cranial neural crest cells form corridors prefiguring sensory neuroblast migration. Development 2013; 140:3595-600. [PMID: 23942515 PMCID: PMC3742142 DOI: 10.1242/dev.091033] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The majority of cranial sensory neurons originate in placodes in the surface ectoderm, migrating to form ganglia that connect to the central nervous system (CNS). Interactions between inward-migrating sensory neuroblasts and emigrant cranial neural crest cells (NCCs) play a role in coordinating this process, but how the relationship between these two cell populations is established is not clear. Here, we demonstrate that NCCs generate corridors delineating the path of migratory neuroblasts between the placode and CNS in both chick and mouse. In vitro analysis shows that NCCs are not essential for neuroblast migration, yet act as a superior substrate to mesoderm, suggesting provision of a corridor through a less-permissive mesodermal territory. Early organisation of NCC corridors occurs prior to sensory neurogenesis and can be recapitulated in vitro; however, NCC extension to the placode requires placodal neurogenesis, demonstrating reciprocal interactions. Together, our data indicate that NCC corridors impose physical organisation for precise ganglion formation and connection to the CNS, providing a local environment to enclose migrating neuroblasts and axonal processes as they migrate through a non-neural territory.
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Affiliation(s)
- Sabine Freter
- Department of Physiology, Anatomy and Genetics, University of Oxford, South Parks Road, Oxford, UK
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11
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McGonnell IM, Graham A, Richardson J, Fish JL, Depew MJ, Dee CT, Holland PWH, Takahashi T. Evolution of the Alx homeobox gene family: parallel retention and independent loss of the vertebrate Alx3 gene. Evol Dev 2011; 13:343-51. [PMID: 21740507 PMCID: PMC3166657 DOI: 10.1111/j.1525-142x.2011.00489.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The Alx gene family is implicated in craniofacial development and comprises two to four homeobox genes in each vertebrate genome analyzed. Using phylogenetics and comparative genomics, we show that the common ancestor of jawed vertebrates had three Alx genes descendent from the two-round genome duplications (Alx1, Alx3, Alx4), compared with a single amphioxus gene. Later in evolution one of the paralogues, Alx3, was lost independently from at least three different vertebrate lineages, whereas Alx1 and Alx4 were consistently retained. Comparison of spatial gene expression patterns reveals that the three mouse genes have equivalent craniofacial expression to the two chick and frog genes, suggesting that redundancy compensated for gene loss. We suggest that multiple independent loss of one Alx gene was predisposed by extensive and persistent overlap in gene expression between Alx paralogues. Even so, it is unclear whether it was coincidence or evolutionary bias that resulted in the same Alx gene being lost on each occasion, rather than different members of the gene family.
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Affiliation(s)
- Imelda M McGonnell
- Reproduction and Development, The Royal Veterinary CollegeRoyal College Street, London NW1 0TU, UK
| | - Anthony Graham
- MRC Centre for Developmental Neurobiology, King's College London, New Hunt's HouseGuy's Hospital Campus, London SE1 1UL, UK
| | - Joanna Richardson
- MRC Centre for Developmental Neurobiology, King's College London, New Hunt's HouseGuy's Hospital Campus, London SE1 1UL, UK
| | - Jennifer L Fish
- Department of Craniofacial Development, King's College London, Guy's HospitalLondon Bridge, London SE1 9RT, UK
| | - Michael J Depew
- Department of Craniofacial Development, King's College London, Guy's HospitalLondon Bridge, London SE1 9RT, UK
- Department of Orthopaedic Surgery, University of California San Francisco2550 24th Street, SFGH Bldg 9, San Francisco, CA 94110, USA
| | - Chris T Dee
- Faculty of Life Sciences, The University of Manchester, Michael Smith BuildingOxford Road, Manchester M13 9PT, UK
| | - Peter WH Holland
- Department of Zoology, University of OxfordTinbergen Building, South Parks Road, Oxford OX1 3PS, UK
| | - Tokiharu Takahashi
- Faculty of Life Sciences, The University of Manchester, Michael Smith BuildingOxford Road, Manchester M13 9PT, UK
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12
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Blentic A, Chambers D, Skinner A, Begbie J, Graham A. The formation of the cranial ganglia by placodally-derived sensory neuronal precursors. Mol Cell Neurosci 2011; 46:452-9. [DOI: 10.1016/j.mcn.2010.11.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Revised: 11/12/2010] [Accepted: 11/17/2010] [Indexed: 10/18/2022] Open
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13
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Thompson H, Griffiths JS, Jeffery G, McGonnell IM. The retinal pigment epithelium of the eye regulates the development of scleral cartilage. Dev Biol 2010; 347:40-52. [PMID: 20707994 PMCID: PMC2977850 DOI: 10.1016/j.ydbio.2010.08.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2010] [Revised: 07/28/2010] [Accepted: 08/03/2010] [Indexed: 01/01/2023]
Abstract
The majority of vertebrate species have a layer of hyaline cartilage within the fibrous sclera giving an extra degree of support to the eyeball. In chicks, this is seen as a cuplike structure throughout the scleral layer. However, the mechanisms that control the development of scleral cartilage are largely unknown. Here we have studied the phases of scleral cartilage development and characterised expression profiles of genes activated during the cartilage differentiation programme. CART1 and SOX9, the earliest markers of pre-committed cartilage, are expressed in the mesenchyme surrounding the optic cup. Later AGGRECAN, a matrix protein expressed during chondrocyte differentiation, is also expressed. The expression of these genes is lost following early removal of the optic cup, suggesting a role for this tissue in inducing scleral cartilage. By grafting young retinal pigment epithelium (RPE) and retina into cranial mesenchyme in vivo, it was found that RPE alone has the ability to induce cartilage formation. There are some exceptions within the vertebrates where scleral cartilage is not present; one such example is the placental mammals. However, we found that the cartilage differentiation pathway is initiated in mice as seen by the expression of Cart1 and Sox9, but expression of the later cartilage marker Aggrecan is weak. Furthermore, cartilage forms in mouse peri-ocular mesenchyme micromass culture. This suggests that the process halts in vivo before full differentiation into cartilage, but that murine scleral mesenchyme has retained the potential to make cartilage in vitro. RA, Wnts and Bmps have been linked to the cartilage development process and are expressed within the developing RPE. We find that RA may have a role in early scleral cartilage development but is not likely to be the main factor involved. These data reveal the course of scleral cartilage formation and highlight the key role that the optic cup plays in this process. The driving element within the optic cup is almost certainly the retinal pigmented epithelium.
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Affiliation(s)
- H Thompson
- Department of Veterinary Basic Science, Royal Veterinary College, London, NW1 0TU, UK
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