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De Magalhães CG, Cvekl A, Jaeger RG, Yan CYI. Lens placode modulates extracellular matrix formation during early eye development. Differentiation 2024; 138:100792. [PMID: 38935992 PMCID: PMC11247415 DOI: 10.1016/j.diff.2024.100792] [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: 03/26/2024] [Revised: 06/13/2024] [Accepted: 06/20/2024] [Indexed: 06/29/2024]
Abstract
The role extracellular matrix (ECM) in multiple events of morphogenesis has been well described, little is known about its specific role in early eye development. One of the first morphogenic events in lens development is placodal thickening, which converts the presumptive lens ectoderm from cuboidal to pseudostratified epithelium. This process occurs in the anterior pre-placodal ectoderm when the optic vesicle approaches the cephalic ectoderm and is regulated by transcription factor Pax6 and secreted BMP4. Since cells and ECM have a dynamic relationship of interdependence and modulation, we hypothesized that the ECM evolves with cell shape changes during lens placode formation. This study investigates changes in optic ECM including both protein distribution deposition, extracellular gelatinase activity and gene expression patterns during early optic development using chicken and mouse models. In particular, the expression of Timp2, a metalloprotease inhibitor, corresponds with a decrease in gelatinase activity within the optic ECM. Furthermore, we demonstrate that optic ECM remodeling depends on BMP signaling in the placode. Together, our findings suggest that the lens placode plays an active role in remodeling the optic ECM during early eye development.
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Affiliation(s)
- Cecília G De Magalhães
- Department of Cell and Developmental Biology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, SP, 05508-900, Brazil
| | - Ales Cvekl
- Department of Ophthalmology and Visual Sciences and Genetics, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Ruy G Jaeger
- Department of Cell and Developmental Biology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, SP, 05508-900, Brazil
| | - C Y Irene Yan
- Department of Cell and Developmental Biology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, SP, 05508-900, Brazil.
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2
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Goh J, Wei H, Lai AHM, Chang B, Khan S, Syn Y, Jamuar SS, Tan EC. Novel and recurrent variants in PAX6 in four patients with ocular phenotypes from Southeast Asia. Clin Dysmorphol 2024; 33:63-68. [PMID: 38441200 DOI: 10.1097/mcd.0000000000000487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2024]
Abstract
Aniridia is an autosomal dominant condition characterized by the complete or partial absence of the iris, often with additional presentations such as foveal hypoplasia, nystagmus, cataract, glaucoma and other ocular abnormalities. Most cases are caused by heterozygous mutations in the paired box 6 gene (PAX6), which codes for a transcription factor that regulates eye development. Four patients from our hospital who presented with ocular phenotypes were recruited for research sequencing with informed consent. Sanger sequencing of PAX6 coding exons or exome sequencing was performed on genomic DNA from venous blood samples. Variants in PAX6 were identified in the four patients. Two variants are recurrent single-nucleotide substitutions - one is a substitution found in a patient with bilateral aniridia, whereas the other is a splice variant in a patient with nystagmus and neuroblastoma. The other two variants are novel and found in two patients with isolated aniridia. Both are small duplications that are predicted to lead to premature termination. For the recurrent variants, the comparison of phenotypes for patients with identical variants would shed light on the mechanisms of pathogenesis, and the discovery of two novel variants expands the spectrum of PAX6 mutations.
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Affiliation(s)
- Jeannette Goh
- Genetics Service, Department of Paediatrics, KK Women's and Children's Hospital
- Paediatrics Academic Clinical Programme, SingHealth Duke-NUS Medical School
| | - Heming Wei
- Research Laboratory, KK Women's and Children's Hospital
| | - Angeline H M Lai
- Genetics Service, Department of Paediatrics, KK Women's and Children's Hospital
- Paediatrics Academic Clinical Programme, SingHealth Duke-NUS Medical School
| | - Benjamin Chang
- Opthalmology Service, KK Women's and Children's Hospital
| | - Shazia Khan
- Opthalmology Service, KK Women's and Children's Hospital
| | - Yamon Syn
- Singapore National Eye Centre, Singapore
| | - Saumya S Jamuar
- Genetics Service, Department of Paediatrics, KK Women's and Children's Hospital
- Paediatrics Academic Clinical Programme, SingHealth Duke-NUS Medical School
| | - Ene-Choo Tan
- Paediatrics Academic Clinical Programme, SingHealth Duke-NUS Medical School
- Research Laboratory, KK Women's and Children's Hospital
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3
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De Magalhães CG, Cvekl A, Jaeger RG, Yan CYI. Lens Placode Modulates Extracellular Matrix Formation During Early Eye Development. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.11.30.569417. [PMID: 38076974 PMCID: PMC10705410 DOI: 10.1101/2023.11.30.569417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/07/2024]
Abstract
The role extracellular matrix (ECM) in multiple events of morphogenesis has been well described, little is known about its specific role in early eye development. One of the first morphogenic events in lens development is placodal thickening, which converts the presumptive lens ectoderm from cuboidal to pseudostratified epithelium. This process occurs in the anterior pre-placodal ectoderm when the optic vesicle approaches the cephalic ectoderm. Since cells and ECM have a dynamic relationship of interdependence and modulation, we hypothesized that the ECM evolves with cell shape changes during lens placode formation. This study investigates changes in optic ECM including both protein distribution deposition, extracellular gelatinase activity and gene expression patterns during early optic development using chicken and mouse models. In particular, the expression of Timp2 , a metalloprotease inhibitor, corresponds with a decrease in gelatinase activity within the optic ECM. Furthermore, we demonstrate that optic ECM remodeling depends on BMP signaling in the placode. Together, our findings suggest that the lens placode plays an active role in remodeling the optic ECM during early eye development.
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4
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Tophkhane SS, Richman JM. Tissues and signals with true organizer properties in craniofacial development. Curr Top Dev Biol 2023; 157:67-82. [PMID: 38556459 DOI: 10.1016/bs.ctdb.2023.12.002] [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: 04/02/2024]
Abstract
Transplantation experiments have shown that a true organizer provides instructive signals that induce and pattern ectopic structures in the responding tissue. Here, we review craniofacial experiments to identify tissues with organizer properties and signals with organizer properties. In particular, we evaluate whether transformation of identity took place in the mesenchyme. Using these stringent criteria, we find the strongest evidence for the avian foregut ectoderm. Transplanting a piece of quail foregut endoderm to a host chicken embryo caused ectopic beaks to form derived from chicken mesenchyme. The beak identity, whether upper or lower as well as orientation, was controlled by the original anterior-posterior position of the donor endoderm. There is also good evidence that the nasal pit is necessary and sufficient for lateral nasal patterning. Finally, we review signals that have organizer properties on their own without the need for tissue transplants. Mouse germline knockouts of the endothelin pathway result in transformation of identity of the mandible into a maxilla. Application of noggin-soaked beads to post-migratory neural crest cells transforms maxillary identity. This suggests that endothelin or noggin rich ectoderm could be organizers (not tested). In conclusion, craniofacial, neural crest-derived mesenchyme is competent to respond to tissues with organizer properties, also originating in the head. In future, we can exploit such well defined systems to dissect the molecular changes that ultimately lead to patterning of the upper and lower jaw.
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Affiliation(s)
- Shruti S Tophkhane
- Life Sciences Institute and Faculty of Dentistry, University of British Columbia, Vancouver, BC, Canada
| | - Joy M Richman
- Life Sciences Institute and Faculty of Dentistry, University of British Columbia, Vancouver, BC, Canada
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5
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Koontz A, Urrutia HA, Bronner ME. Retroviral lineage analysis reveals dual contribution from ectodermal placodes and neural crest cells to avian olfactory sensory and GnRH neurons. NATURAL SCIENCES (WEINHEIM, GERMANY) 2022; 2:e20210037. [PMID: 36311264 PMCID: PMC9605686 DOI: 10.1002/ntls.20210037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The origin of the neurons and glia in the olfactory system of vertebrates has been controversial, with different cell types attributed to being of ectodermal placode versus neural crest lineage, depending upon the species. Here, we use replication incompetent avian (RIA) retroviruses to perform prospective cell lineage analysis of either presumptive olfactory placode or neural crest cells during early development of the chick embryo. Surprisingly, the results reveal a dual contribution from both the olfactory placode and neural crest cells to sensory neurons in the nose and Gonadotropin Releasing Hormone (GnRH) neurons migrating to the olfactory bulb. We also confirm that olfactory ensheathing glia are solely derived from the neural crest. Finally, our results show that neural crest cells and olfactory placode cells contribute to p63 positive cells, likely to be basal stem cells of the olfactory epithelium. Taken together, these finding provide evidence for previously unknown contributions of neural crest cells to some cell types in the chick olfactory system and help resolve previous discrepancies in the literature.
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Affiliation(s)
- Alison Koontz
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125
| | - Hugo A Urrutia
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125
| | - Marianne E Bronner
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125
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6
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Making a head: Neural crest and ectodermal placodes in cranial sensory development. Semin Cell Dev Biol 2022; 138:15-27. [PMID: 35760729 DOI: 10.1016/j.semcdb.2022.06.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 04/11/2022] [Accepted: 06/19/2022] [Indexed: 01/04/2023]
Abstract
During development of the vertebrate sensory system, many important components like the sense organs and cranial sensory ganglia arise within the head and neck. Two progenitor populations, the neural crest, and cranial ectodermal placodes, contribute to these developing vertebrate peripheral sensory structures. The interactions and contributions of these cell populations to the development of the lens, olfactory, otic, pituitary gland, and cranial ganglia are vital for appropriate peripheral nervous system development. Here, we review the origins of both neural crest and placode cells at the neural plate border of the early vertebrate embryo and investigate the molecular and environmental signals that influence specification of different sensory regions. Finally, we discuss the underlying molecular pathways contributing to the complex vertebrate sensory system from an evolutionary perspective, from basal vertebrates to amniotes.
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Roffers-Agarwal J, Lidberg KA, Gammill LS. The lysine methyltransferase SETD2 is a dynamically expressed regulator of early neural crest development. Genesis 2021; 59:e23448. [PMID: 34498354 DOI: 10.1002/dvg.23448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 07/31/2021] [Accepted: 08/13/2021] [Indexed: 11/11/2022]
Abstract
SETD2 is a histone H3 lysine 36 (H3K36) tri-methylase that is upregulated in response to neural crest induction. Because the H3K36 di-methylase NSD3 and cytoplasmic non-histone protein methylation are necessary for neural crest development, we investigated the expression and requirement for SETD2 in the neural crest. SetD2 is expressed throughout the chick blastoderm beginning at gastrulation. Subsequently, SetD2 mRNA becomes restricted to the neural plate, where it is strongly and dynamically expressed as neural tissue is regionalized and cell fate decisions are made. This includes expression in premigratory neural crest cells, which is downregulated prior to migration. Likely due to the early onset of its expression, SETD2 morpholino knockdown does not significantly alter premigratory Sox10 expression or neural crest migration; however, both are disrupted by a methyltransferase mutant SETD2 construct. These results suggest that SETD2 activity is essential for early neural crest development, further demonstrating that lysine methylation is an important mechanism regulating the neural crest.
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Affiliation(s)
- Julaine Roffers-Agarwal
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota, USA.,Developmental Biology Center, University of Minnesota, Minneapolis, Minnesota, USA
| | - Kevin A Lidberg
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota, USA.,Developmental Biology Center, University of Minnesota, Minneapolis, Minnesota, USA
| | - Laura S Gammill
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota, USA.,Developmental Biology Center, University of Minnesota, Minneapolis, Minnesota, USA
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8
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Katreddi RR, Forni PE. Mechanisms underlying pre- and postnatal development of the vomeronasal organ. Cell Mol Life Sci 2021; 78:5069-5082. [PMID: 33871676 PMCID: PMC8254721 DOI: 10.1007/s00018-021-03829-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 03/17/2021] [Accepted: 03/29/2021] [Indexed: 02/06/2023]
Abstract
The vomeronasal organ (VNO) is sensory organ located in the ventral region of the nasal cavity in rodents. The VNO develops from the olfactory placode during the secondary invagination of olfactory pit. The embryonic vomeronasal structure appears as a neurogenic area where migratory neuronal populations like endocrine gonadotropin-releasing hormone-1 (GnRH-1) neurons form. Even though embryonic vomeronasal structures are conserved across most vertebrate species, many species including humans do not have a functional VNO after birth. The vomeronasal epithelium (VNE) of rodents is composed of two major types of vomeronasal sensory neurons (VSNs): (1) VSNs distributed in the apical VNE regions that express vomeronasal type-1 receptors (V1Rs) and the G protein subunit Gαi2, and (2) VSNs in the basal territories of the VNE that express vomeronasal type-2 receptors (V2Rs) and the G subunit Gαo. Recent studies identified a third subclass of Gαi2 and Gαo VSNs that express the formyl peptide receptor family. VSNs expressing V1Rs or V2Rs send their axons to distinct regions of the accessory olfactory bulb (AOB). Together, VNO and AOB form the accessory olfactory system (AOS), an olfactory subsystem that coordinates the social and sexual behaviors of many vertebrate species. In this review, we summarize our current understanding of cellular and molecular mechanisms that underlie VNO development. We also discuss open questions for study, which we suggest will further enhance our understanding of VNO morphogenesis at embryonic and postnatal stages.
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Affiliation(s)
- Raghu Ram Katreddi
- Department of Biological Sciences, Center for Neuroscience Research, The RNA Institute, University At Albany, State University of New York, Albany, NY, USA
| | - Paolo E Forni
- Department of Biological Sciences, Center for Neuroscience Research, The RNA Institute, University At Albany, State University of New York, Albany, NY, USA.
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Dlx5-augmentation in neural crest cells reveals early development and differentiation potential of mouse apical head mesenchyme. Sci Rep 2021; 11:2092. [PMID: 33483579 PMCID: PMC7822927 DOI: 10.1038/s41598-021-81434-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 01/05/2021] [Indexed: 11/08/2022] Open
Abstract
Neural crest cells (NCCs) give rise to various tissues including neurons, pigment cells, bone and cartilage in the head. Distal-less homeobox 5 (Dlx5) is involved in both jaw patterning and differentiation of NCC-derivatives. In this study, we investigated the differentiation potential of head mesenchyme by forcing Dlx5 to be expressed in mouse NCC (NCCDlx5). In NCCDlx5 mice, differentiation of dermis and pigment cells were enhanced with ectopic cartilage (ec) and heterotopic bone (hb) in different layers at the cranial vertex. The ec and hb were derived from the early migrating mesenchyme (EMM), the non-skeletogenic cell population located above skeletogenic supraorbital mesenchyme (SOM). The ec developed within Foxc1+-dura mater with increased PDGFRα signalling, and the hb formed with upregulation of BMP and WNT/β-catenin signallings in Dermo1+-dermal layer from E11.5. Since dermal cells express Runx2 and Msx2 in the control, osteogenic potential in dermal cells seemed to be inhibited by an anti-osteogenic function of Msx2 in normal context. We propose that, after the non-skeletogenic commitment, the EMM is divided into dermis and meninges by E11.5 in normal development. Two distinct responses of the EMM, chondrogenesis and osteogenesis, to Dlx5-augmentation in the NCCDlx5 strongly support this idea.
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10
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Cell fate decisions during the development of the peripheral nervous system in the vertebrate head. Curr Top Dev Biol 2020; 139:127-167. [PMID: 32450959 DOI: 10.1016/bs.ctdb.2020.04.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Sensory placodes and neural crest cells are among the key cell populations that facilitated the emergence and diversification of vertebrates throughout evolution. Together, they generate the sensory nervous system in the head: both form the cranial sensory ganglia, while placodal cells make major contributions to the sense organs-the eye, ear and olfactory epithelium. Both are instrumental for integrating craniofacial organs and have been key to drive the concentration of sensory structures in the vertebrate head allowing the emergence of active and predatory life forms. Whereas the gene regulatory networks that control neural crest cell development have been studied extensively, the signals and downstream transcriptional events that regulate placode formation and diversity are only beginning to be uncovered. Both cell populations are derived from the embryonic ectoderm, which also generates the central nervous system and the epidermis, and recent evidence suggests that their initial specification involves a common molecular mechanism before definitive neural, neural crest and placodal lineages are established. In this review, we will first discuss the transcriptional networks that pattern the embryonic ectoderm and establish these three cell fates with emphasis on sensory placodes. Second, we will focus on how sensory placode precursors diversify using the specification of otic-epibranchial progenitors and their segregation as an example.
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11
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Hadziselimovic F, Verkauskas G, Vincel B, Stadler MB. Testicular expression of long non-coding RNAs is affected by curative GnRHa treatment of cryptorchidism. Basic Clin Androl 2019; 29:18. [PMID: 31890219 PMCID: PMC6933710 DOI: 10.1186/s12610-019-0097-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 12/10/2019] [Indexed: 12/27/2022] Open
Abstract
Background Cryptorchidism is a frequent endocrinopathy in boys that has been associated with an increased risk of developing testicular cancer and infertility. The condition is curable by combined surgery and hormonal treatment during early pre-pubertal stages using gonadotropin releasing hormone agonist (GnRHa). However, whether the treatment also alters the expression of testicular long non-coding RNAs (lncRNAs) is unknown. To gain insight into the effect of GnRHa on testicular lncRNA levels, we re-analyzed an expression dataset generated from testicular biopsies obtained during orchidopexy for bilateral cryptorchidism. Results We identified EGFR-AS1, Linc-ROR, LINC00221, LINC00261, LINC00282, LINC00293, LINC00303, LINC00898, LINC00994, LINC01121, LINC01553, and MTOR-AS1 as potentially relevant for the stimulation of cell proliferation mediated by GnRHa based on their direct or indirect association with rapidly dividing cells in normal and pathological tissues. Surgery alone failed to alter the expression of these transcripts. Conclusion Given that lncRNAs can cooperate with chromatin-modifying enzymes to promote epigenetic regulation of genes, GnRHa treatment may act as a surrogate for mini-puberty by triggering the differentiation of Ad spermatogonia via lncRNA-mediated epigenetic effects. Our work provides additional molecular evidence that infertility and azoospermia in cryptorchidism, resulting from defective mini-puberty cannot be cured with successful orchidopexy alone.
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Affiliation(s)
- Faruk Hadziselimovic
- Cryptorchidism Research Institute, Children's Day Care Center, 4410 Liestal, Switzerland
| | - Gilvydas Verkauskas
- 2Children's Surgery Centre, Faculty of Medicine, Vilnius University, 01513 Vilnius, Lithuania
| | - Beata Vincel
- 3Children's Surgery Centre, Clinic of Gastroenterology, Nephrourology and Surgery, Institute of Clinical Medicine, Faculty of Medicine, Vilnius University, Vilnius, Lithuania
| | - Michael B Stadler
- 4Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.,5Swiss Institute of Bioinformatics, Basel, Switzerland
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12
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Transplantation of Neural Tissue: Quail-Chick Chimeras. Methods Mol Biol 2019. [PMID: 31552671 DOI: 10.1007/978-1-4939-9732-9_26] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Tissue transplantation is an important approach in developmental neurobiology to determine cell fate, to uncover inductive interactions required for tissue specification and patterning as well as to establish tissue competence and commitment. Combined with state-of-the-art molecular approaches, transplantation assays have been instrumental for the discovery of gene regulatory networks controlling cell fate choices and how such networks change over time. Avian species are among the favorite model systems for these approaches because of their accessibility and relatively large size. Here we describe two culture techniques used to generate quail-chick chimeras at different embryonic stages and methods to distinguish graft and donor tissue.
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Panaliappan TK, Wittmann W, Jidigam VK, Mercurio S, Bertolini JA, Sghari S, Bose R, Patthey C, Nicolis SK, Gunhaga L. Sox2 is required for olfactory pit formation and olfactory neurogenesis through BMP restriction and Hes5 upregulation. Development 2018; 145:145/2/dev153791. [PMID: 29352015 PMCID: PMC5825848 DOI: 10.1242/dev.153791] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 12/11/2017] [Indexed: 12/26/2022]
Abstract
The transcription factor Sox2 is necessary to maintain pluripotency of embryonic stem cells, and to regulate neural development. Neurogenesis in the vertebrate olfactory epithelium persists from embryonic stages through adulthood. The role Sox2 plays for the development of the olfactory epithelium and neurogenesis within has, however, not been determined. Here, by analysing Sox2 conditional knockout mouse embryos and chick embryos deprived of Sox2 in the olfactory epithelium using CRISPR-Cas9, we show that Sox2 activity is crucial for the induction of the neural progenitor gene Hes5 and for subsequent differentiation of the neuronal lineage. Our results also suggest that Sox2 activity promotes the neurogenic domain in the nasal epithelium by restricting Bmp4 expression. The Sox2-deficient olfactory epithelium displays diminished cell cycle progression and proliferation, a dramatic increase in apoptosis and finally olfactory pit atrophy. Moreover, chromatin immunoprecipitation data show that Sox2 directly binds to the Hes5 promoter in both the PNS and CNS. Taken together, our results indicate that Sox2 is essential to establish, maintain and expand the neuronal progenitor pool by suppressing Bmp4 and upregulating Hes5 expression. Summary: Analysis of Sox2 mutant mouse and Sox2 CRISPR-targeted chick embryos reveals that Sox2 controls the establishment of sensory progenitors in the olfactory epithelium by suppressing Bmp4 and upregulating Hes5 expression.
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Affiliation(s)
| | - Walter Wittmann
- Umeå Centre for Molecular Medicine, Umeå University, 901 87 Umeå, Sweden
| | - Vijay K Jidigam
- Umeå Centre for Molecular Medicine, Umeå University, 901 87 Umeå, Sweden
| | - Sara Mercurio
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, 20126 Milan, Italy
| | - Jessica A Bertolini
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, 20126 Milan, Italy
| | - Soufien Sghari
- Umeå Centre for Molecular Medicine, Umeå University, 901 87 Umeå, Sweden
| | - Raj Bose
- Umeå Centre for Molecular Medicine, Umeå University, 901 87 Umeå, Sweden
| | - Cedric Patthey
- Umeå Centre for Molecular Medicine, Umeå University, 901 87 Umeå, Sweden
| | - Silvia K Nicolis
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, 20126 Milan, Italy
| | - Lena Gunhaga
- Umeå Centre for Molecular Medicine, Umeå University, 901 87 Umeå, Sweden
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Nasal and otic placode specific regulation of Sox2 involves both activation by Sox-Sall4 synergism and multiple repression mechanisms. Dev Biol 2018; 433:61-74. [DOI: 10.1016/j.ydbio.2017.11.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Revised: 11/02/2017] [Accepted: 11/10/2017] [Indexed: 01/21/2023]
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15
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Sanchez-Arrones L, Sandonís Á, Cardozo MJ, Bovolenta P. Adenohypophysis placodal precursors exhibit distinctive features within the rostral preplacodal ectoderm. Development 2017; 144:3521-3532. [PMID: 28974641 DOI: 10.1242/dev.149724] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Accepted: 08/14/2017] [Indexed: 11/20/2022]
Abstract
Placodes are discrete thickenings of the vertebrate cranial ectoderm that generate morpho-functionally distinct structures, such as the adenohypophysis, olfactory epithelium and lens. All placodes arise from a horseshoe-shaped preplacodal ectoderm in which the precursors of individual placodes are intermingled. However, fate-map studies indicated that cells positioned at the preplacodal midline give rise to only the adenohypophyseal placode, suggesting a unique organization of these precursors within the preplacode. To test this possibility, we combined embryological and molecular approaches in chick embryos to show that, at gastrula stage, adenohypophyseal precursors are clustered in the median preplacodal ectoderm, largely segregated from those of the adjacent olfactory placode. Median precursors are elongated, densely packed and, at neurula stage, express a molecular signature that distinguishes them from the remaining preplacodal cells. Olfactory placode precursors and midline neural cells can replace ablated adenohypophyseal precursors up to head-fold stage, although with a more plastic organization. We thus propose that adenohypophyseal placode precursors are unique within the preplacodal ectoderm possibly because they originate the only single placode and the only one with an endocrine character.
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Affiliation(s)
- Luisa Sanchez-Arrones
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, c/ Nicolás Cabrera 1, Madrid 28049, Spain.,CIBER de Enfermedades Raras (CIBERER), c/ Nicolás Cabrera 1, Madrid 28049, Spain
| | - África Sandonís
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, c/ Nicolás Cabrera 1, Madrid 28049, Spain.,CIBER de Enfermedades Raras (CIBERER), c/ Nicolás Cabrera 1, Madrid 28049, Spain
| | - Marcos Julián Cardozo
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, c/ Nicolás Cabrera 1, Madrid 28049, Spain.,CIBER de Enfermedades Raras (CIBERER), c/ Nicolás Cabrera 1, Madrid 28049, Spain
| | - Paola Bovolenta
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, c/ Nicolás Cabrera 1, Madrid 28049, Spain .,CIBER de Enfermedades Raras (CIBERER), c/ Nicolás Cabrera 1, Madrid 28049, Spain
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16
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Aguillon R, Blader P, Batut J. Patterning, morphogenesis, and neurogenesis of zebrafish cranial sensory placodes. Methods Cell Biol 2016; 134:33-67. [PMID: 27312490 DOI: 10.1016/bs.mcb.2016.01.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Peripheral sensory organs and ganglia found in the vertebrate head arise during embryonic development from distinct ectodermal thickenings, called cranial sensory placodes (adenohypophyseal, olfactory, lens, trigeminal, epibranchial, and otic). A series of patterning events leads to the establishment of these placodes. Subsequently, these placodes undergo specific morphogenetic movements and cell-type specification in order to shape the final placodal derivatives and to produce differentiated cell types necessary for their function. In this chapter, we will focus on recent studies in the zebrafish that have advanced our understanding of cranial sensory placode development. We will summarize the signaling events and their molecular effectors guiding the formation of the so-called preplacodal region, and the subsequent subdivision of this region along the anteroposterior axis that gives rise to specific placode identities as well as those controlling morphogenesis and neurogenesis. Finally, we will highlight the approaches used in zebrafish that have been established to precisely label cell populations, to follow their development, and/or to characterize cell fates within a specific placode.
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Affiliation(s)
- R Aguillon
- Centre de Biologie du Développement (CBD, UMR5547), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, Toulouse, France
| | - P Blader
- Centre de Biologie du Développement (CBD, UMR5547), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, Toulouse, France
| | - J Batut
- Centre de Biologie du Développement (CBD, UMR5547), Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, Toulouse, France
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Ezin M, Barembaum M, Bronner ME. Stage-dependent plasticity of the anterior neural folds to form neural crest. Differentiation 2014; 88:42-50. [PMID: 25264214 DOI: 10.1016/j.diff.2014.09.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Revised: 06/06/2014] [Accepted: 09/06/2014] [Indexed: 12/21/2022]
Abstract
The anterior neural fold (ANF) is the only region of the neural tube that does not produce neural crest cells. Instead, ANF cells contribute to the olfactory and lens placodes, as well as to the forebrain and epidermis. Here, we test the ability of the ANF to form neural crest by performing heterotopic transplantation experiments in the chick embryo. We find that, at the neurula stage (HH stage 7), the chick ANF retains the ability to form migrating neural crest cells when transplanted caudally to rostral hindbrain levels. This ability is gradually lost, such that by HH9, this tissue appears to no longer have the potential to form neural crest. In contrast to the ANF, hindbrain dorsal neural folds transplanted rostrally fail to contribute to the olfactory placode but instead continue to generate neural crest cells. The transcription factor GANF is expressed in the ANF and its morpholino-mediated knock-down expands the neural crest domain rostrally and results in the production of migratory cells emerging from the ANF; however, these cells fail to express the HNK1 neural crest marker, suggesting only partial conversion. Our results show that environmental factors can imbue the chick anterior neural folds to assume a neural crest cell fate via a mechanism that partially involves loss of GANF.
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Affiliation(s)
- Maxellende Ezin
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, United States
| | - Meyer Barembaum
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, United States
| | - Marianne E Bronner
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, United States.
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Bhattacharyya S, Bronner ME. Clonal analyses in the anterior pre-placodal region: implications for the early lineage bias of placodal progenitors. THE INTERNATIONAL JOURNAL OF DEVELOPMENTAL BIOLOGY 2014; 57:753-7. [PMID: 24307294 DOI: 10.1387/ijdb.130155mb] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Cranial ectodermal placodes, a vertebrate innovation, contribute to the adenohypophysis and peripheral nervous system of the head, including the paired sense organs (eyes, nose, ears) and sensory ganglia of the Vth, VIIth, IXth and Xth cranial nerves. Fate-maps of groups of cells in amphibians, teleosts and amniotes have demonstrated that all placodes have a common origin in a horseshoe shaped territory, known as the preplacodal region (PPR), which surrounds the presumptive neural plate of the late gastrula/early neurula stage embryo. Given the extensive regional overlap of progenitors for different placodes in the chick embryo, it has been a matter of debate as to whether individual cells in the PPR are truly multipotent progenitors, with regard to placodal identity, or rather are lineage-biased or restricted to a specific placodal type prior to overt differentiation. Utilizing clonal analyses in vivo, we demonstrate here that the anterior PPR comprises some precursors that contribute either to the olfactory or lens placode well before they are spatially segregated or committed to either of these placodal fates. This suggests that lineage bias towards a specific placodal fate may coincide with induction of the PPR.
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20
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Yao D, Zhao F, Wu Y, Wang J, Dong W, Zhao J, Zhu Z, Liu D. Dissecting the differentiation process of the preplacodal ectoderm in zebrafish. Dev Dyn 2014; 243:1338-51. [DOI: 10.1002/dvdy.24160] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 06/21/2014] [Accepted: 06/23/2014] [Indexed: 01/13/2023] Open
Affiliation(s)
- Di Yao
- The Education Ministry Key Laboratory of Cell Proliferation and Differentiation and the State Key Laboratory of Bio-membrane and Membrane Bio-engineering; School of Life Sciences; Peking University; Beijing China
| | - Feng Zhao
- The Education Ministry Key Laboratory of Cell Proliferation and Differentiation and the State Key Laboratory of Bio-membrane and Membrane Bio-engineering; School of Life Sciences; Peking University; Beijing China
| | - Ying Wu
- The Education Ministry Key Laboratory of Cell Proliferation and Differentiation and the State Key Laboratory of Bio-membrane and Membrane Bio-engineering; School of Life Sciences; Peking University; Beijing China
| | - Jialiang Wang
- The Education Ministry Key Laboratory of Cell Proliferation and Differentiation and the State Key Laboratory of Bio-membrane and Membrane Bio-engineering; School of Life Sciences; Peking University; Beijing China
| | - Wei Dong
- The Education Ministry Key Laboratory of Cell Proliferation and Differentiation and the State Key Laboratory of Bio-membrane and Membrane Bio-engineering; School of Life Sciences; Peking University; Beijing China
| | - Jue Zhao
- The Education Ministry Key Laboratory of Cell Proliferation and Differentiation and the State Key Laboratory of Bio-membrane and Membrane Bio-engineering; School of Life Sciences; Peking University; Beijing China
| | - Zuoyan Zhu
- The Education Ministry Key Laboratory of Cell Proliferation and Differentiation and the State Key Laboratory of Bio-membrane and Membrane Bio-engineering; School of Life Sciences; Peking University; Beijing China
| | - Dong Liu
- The Education Ministry Key Laboratory of Cell Proliferation and Differentiation and the State Key Laboratory of Bio-membrane and Membrane Bio-engineering; School of Life Sciences; Peking University; Beijing China
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21
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Koehler KR, Hashino E. 3D mouse embryonic stem cell culture for generating inner ear organoids. Nat Protoc 2014; 9:1229-44. [PMID: 24784820 DOI: 10.1038/nprot.2014.100] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
This protocol describes a culture system in which inner-ear sensory tissue is produced from mouse embryonic stem (ES) cells under chemically defined conditions. This model is amenable to basic and translational investigations into inner ear biology and regeneration. In this protocol, mouse ES cells are aggregated in 96-well plates in medium containing extracellular matrix proteins to promote epithelialization. During the first 14 d, a series of precisely timed protein and small-molecule treatments sequentially induce epithelia that represent the mouse embryonic non-neural ectoderm, preplacodal ectoderm and otic vesicle epithelia. Ultimately, these tissues develop into cysts with a pseudostratified epithelium containing inner ear hair cells and supporting cells after 16-20 d. Concurrently, sensory-like neurons generate synapse-like structures with the derived hair cells. We have designated the stem cell-derived epithelia harboring hair cells, supporting cells and sensory-like neurons as inner ear organoids. This method provides a reproducible and scalable means to generate inner ear sensory tissue in vitro.
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Affiliation(s)
- Karl R Koehler
- 1] Medical Neuroscience Graduate Program, Indiana University School of Medicine, Indianapolis, Indiana, USA. [2] Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, USA. [3] Department of Otolaryngology-Head and Neck Surgery, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Eri Hashino
- 1] Medical Neuroscience Graduate Program, Indiana University School of Medicine, Indianapolis, Indiana, USA. [2] Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, USA. [3] Department of Otolaryngology-Head and Neck Surgery, Indiana University School of Medicine, Indianapolis, Indiana, USA
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22
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Abstract
Tissue transplantation is an important approach in developmental neurobiology to determine cell fate, to uncover inductive interactions required for tissue specification and patterning as well as to establish tissue competence and commitment. Avian species are among the favorite model systems for these approaches because of their accessibility and relatively large size. Here we describe two culture techniques used to generate quail-chick chimeras at different embryonic stages and methods to distinguish graft and donor tissue.
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Affiliation(s)
- Andrea Streit
- Department of Craniofacial Development & Stem Cell Biology, King's College London, London, UK
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23
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Quintana-Urzainqui I, Rodríguez-Moldes I, Candal E. Developmental, tract-tracing and immunohistochemical study of the peripheral olfactory system in a basal vertebrate: insights on Pax6 neurons migrating along the olfactory nerve. Brain Struct Funct 2014; 219:85-104. [PMID: 23224251 PMCID: PMC3889696 DOI: 10.1007/s00429-012-0486-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Accepted: 11/16/2012] [Indexed: 11/02/2022]
Abstract
The olfactory system represents an excellent model for studying different aspects of the development of the nervous system ranging from neurogenesis to mechanisms of axon growth and guidance. Important findings in this field come from comparative studies. We have analyzed key events in the development of the olfactory system of the shark Scyliorhinus canicula by combining immunohistochemical and tract-tracing methods. We describe for the first time in a cartilaginous fish an early population of pioneer HuC/D-immunoreactive (ir) neurons that seemed to delaminate from the olfactory pit epithelium and migrate toward the telencephalon before the olfactory nerve was identifiable. A distinct, transient cell population, namely the migratory mass, courses later on in apposition to the developing olfactory nerve. It contains olfactory ensheathing glial (GFAP-ir) cells and HuC/D-ir neurons, some of which course toward an extrabulbar region. We also demonstrate that Pax6-ir cells coursing along the developing olfactory pathways in S. canicula are young migrating (HuC/D and DCX-ir) neurons of the migratory mass that do not form part of the terminal nerve pathway. Evidences that these Pax6 neurons originate in the olfactory epithelium are also reported. As Pax6 neurons in the olfactory epithelium show characteristics of olfactory receptor neurons, and migrating Pax6-ir neurons formed transient corridors along the course of olfactory axons at the entrance of the olfactory bulb, we propose that these neurons could play a role as guideposts for axons of olfactory receptor neurons growing toward the olfactory bulb.
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Affiliation(s)
- Idoia Quintana-Urzainqui
- Departamento de Biología Celular y Ecología, Edificio CIBUS Campus Vida, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Isabel Rodríguez-Moldes
- Departamento de Biología Celular y Ecología, Edificio CIBUS Campus Vida, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Eva Candal
- Departamento de Biología Celular y Ecología, Edificio CIBUS Campus Vida, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain
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24
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Setting appropriate boundaries: fate, patterning and competence at the neural plate border. Dev Biol 2013; 389:2-12. [PMID: 24321819 DOI: 10.1016/j.ydbio.2013.11.027] [Citation(s) in RCA: 119] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2013] [Revised: 11/26/2013] [Accepted: 11/27/2013] [Indexed: 11/20/2022]
Abstract
The neural crest and craniofacial placodes are two distinct progenitor populations that arise at the border of the vertebrate neural plate. This border region develops through a series of inductive interactions that begins before gastrulation and progressively divide embryonic ectoderm into neural and non-neural regions, followed by the emergence of neural crest and placodal progenitors. In this review, we describe how a limited repertoire of inductive signals-principally FGFs, Wnts and BMPs-set up domains of transcription factors in the border region which establish these progenitor territories by both cross-inhibitory and cross-autoregulatory interactions. The gradual assembly of different cohorts of transcription factors that results from these interactions is one mechanism to provide the competence to respond to inductive signals in different ways, ultimately generating the neural crest and cranial placodes.
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25
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Lleras-Forero L, Tambalo M, Christophorou N, Chambers D, Houart C, Streit A. Neuropeptides: developmental signals in placode progenitor formation. Dev Cell 2013; 26:195-203. [PMID: 23906067 PMCID: PMC3748341 DOI: 10.1016/j.devcel.2013.07.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2012] [Revised: 02/20/2013] [Accepted: 07/02/2013] [Indexed: 02/02/2023]
Abstract
Few families of signaling factors have been implicated in the control of development. Here, we identify the neuropeptides nociceptin and somatostatin, a neurotransmitter and neuroendocrine hormone, as a class of developmental signals in both chick and zebrafish. We show that signals from the anterior mesendoderm are required for the formation of anterior placode progenitors, with one of the signals being somatostatin. Somatostatin controls ectodermal expression of nociceptin, and both peptides regulate Pax6 in lens and olfactory progenitors. Consequently, loss of somatostatin and nociceptin signaling leads to severe reduction of lens formation. Our findings not only uncover these neuropeptides as developmental signals but also identify a long-sought-after mechanism that initiates Pax6 in placode progenitors and may explain the ancient evolutionary origin of neuropeptides, predating a complex nervous system.
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Affiliation(s)
- Laura Lleras-Forero
- Department of Craniofacial Development and Stem Cell Biology, King’s College London, Guy’s Tower Wing, Floor 27, London SE1 9RT, UK
| | - Monica Tambalo
- Department of Craniofacial Development and Stem Cell Biology, King’s College London, Guy’s Tower Wing, Floor 27, London SE1 9RT, UK
| | - Nicolas Christophorou
- Department of Craniofacial Development and Stem Cell Biology, King’s College London, Guy’s Tower Wing, Floor 27, London SE1 9RT, UK
| | - David Chambers
- MRC Centre for Developmental Neurobiology, King’s College London, New Hunts House, London SE1 1UL, UK
| | - Corinne Houart
- MRC Centre for Developmental Neurobiology, King’s College London, New Hunts House, London SE1 1UL, UK
| | - Andrea Streit
- Department of Craniofacial Development and Stem Cell Biology, King’s College London, Guy’s Tower Wing, Floor 27, London SE1 9RT, UK
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26
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Kasberg AD, Brunskill EW, Steven Potter S. SP8 regulates signaling centers during craniofacial development. Dev Biol 2013; 381:312-23. [PMID: 23872235 DOI: 10.1016/j.ydbio.2013.07.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 07/10/2013] [Accepted: 07/11/2013] [Indexed: 01/23/2023]
Abstract
Much of the bone, cartilage and smooth muscle of the vertebrate face is derived from neural crest (NC) cells. During craniofacial development, the anterior neural ridge (ANR) and olfactory pit (OP) signaling centers are responsible for driving the outgrowth, survival, and differentiation of NC populated facial prominences, primarily via FGF. While much is known about the functional importance of signaling centers, relatively little is understood of how these signaling centers are made and maintained. In this report we describe a dramatic craniofacial malformation in mice mutant for the zinc finger transcription factor gene Sp8. At E14.5 they show facial prominences that are reduced in size and underdeveloped, giving an almost faceless phenotype. At later times they show severe midline defects, excencephaly, hyperterlorism, cleft palate, and a striking loss of many NC and paraxial mesoderm derived cranial bones. Sp8 expression was primarily restricted to the ANR and OP regions during craniofacial development. Analysis of an extensive series of conditional Sp8 mutants confirmed the critical role of Sp8 in signaling centers, and not directly in the NC and paraxial mesoderm cells. The NC cells of the Sp8 mutants showed increased levels of apoptosis and decreased cell proliferation, thereby explaining the reduced sizes of the facial prominences. Perturbed gene expression in the Sp8 mutants was examined by laser capture microdissection coupled with microarrays, as well as in situ hybridization and immunostaining. The most dramatic differences included striking reductions in Fgf8 and Fgf17 expression in the ANR and OP signaling centers. We were also able to achieve genetic and pharmaceutical partial rescue of the Sp8 mutant phenotype by reducing Sonic Hedgehog (SHH) signaling. These results show that Sp8 primarily functions to promote Fgf expression in the ANR and OP signaling centers that drive the survival, proliferation, and differentiation of the NC and paraxial mesoderm that make the face.
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Affiliation(s)
- Abigail D Kasberg
- Division of Developmental Biology, Cincinnati Children's Medical Center, Cincinnati, OH 45229, USA
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27
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Differential BMP signaling controls formation and differentiation of multipotent preplacodal ectoderm progenitors from human embryonic stem cells. Dev Biol 2013; 379:208-20. [PMID: 23643939 DOI: 10.1016/j.ydbio.2013.04.023] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Revised: 04/05/2013] [Accepted: 04/22/2013] [Indexed: 01/08/2023]
Abstract
Sensory and endoneurocrine tissues as diverse as the lens, the olfactory epithelium, the inner ear, the cranial sensory ganglia, and the anterior pituitary arise from a common pool of progenitors in the preplacodal ectoderm (PPE). Around late gastrulation, the PPE forms at the border surrounding the anterior neural plate, and expresses a unique set of evolutionarily conserved transcription regulators including Six1, Eya 1 and Eya2. Here, we describe the first report to generate and characterize the SIX1(+) PPE cells from human embryonic stem (ES) cells by adherent differentiation. Before forming PPE cells, differentiating cultures first expressed the non-neural ectoderm specific transcriptional factors TFAP2A, GATA2, GATA3, DLX3, and DLX5, which are crucial in establishing the PPE competence. We demonstrated that bone morphogenetic protein (BMP) activity plays a transient but essential role in inducing expression of these PPE competence factors and eventually the PPE cells. Interestingly, we found that attenuating BMP signaling after establishing the competence state induces anterior placode precursors. By manipulating BMP and hedgehog signaling pathways, we further differentiate these precursors into restricted lineages including the lens placode and the oral ectoderm (pituitary precursor) cells. Finally, we also show that sensory neurons can be generated from human PPE cells, demonstrating the multipotency of the human ES-derived PPE cells.
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28
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Bardet SM, Mouriec K, Balthazart J. Birth of neural progenitors during the embryonic period of sexual differentiation in the Japanese quail brain. J Comp Neurol 2013; 520:4226-53. [PMID: 22628012 DOI: 10.1002/cne.23153] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Several brain areas in the diencephalon are involved in the activation and expression of sexual behavior, including in quail the medial preoptic nucleus (POM). However, the ontogeny of these diencephalic brain nuclei has not to this date been examined in detail. We investigated the ontogeny of POM and other steroid-sensitive brain regions by injecting quail eggs with 5-bromo-2-deoxyuridine (BrdU) at various stages between embryonic day (E)3 and E16 and killing animals at postnatal (PN) days 3 or 56. In the POM, large numbers of BrdU-positive cells were observed in subjects injected from E3-E10, the numbers of these cells was intermediate in birds injected on E12, and most cells were postmitotic in both sexes on E14-E16. Injections on E3-E4 labeled large numbers of Hu-positive cells in POM. In contrast, injections performed at a later stage labeled cells that do not express aromatase nor neuronal markers such as Hu or NeuN in the POM and other steroid-sensitive nuclei and thus do not have a neuronal phenotype in these locations, contrary to what is observed in the telencephalon and cerebellum. No evidence could also be collected to demonstrate that these cells have a glial nature. Converging data, including the facts that these cells divide in the brain mantle and express proliferating cell nuclear antigen (PCNA), a cell cycling marker, indicate that cells labeled by BrdU during the second half of embryonic life are slow-cycling progenitors born and residing in the brain mantle. Future research should now identify their functional significance.
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Affiliation(s)
- Sylvia M Bardet
- GIGA Neurosciences, Research Group in Behavioral Neuroendocrinology, University of Liège, Liège, Belgium
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29
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Holland LZ. Evolution of new characters after whole genome duplications: insights from amphioxus. Semin Cell Dev Biol 2013; 24:101-9. [PMID: 23291260 DOI: 10.1016/j.semcdb.2012.12.007] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Accepted: 12/25/2012] [Indexed: 12/31/2022]
Abstract
Additional copies of genes resulting from two whole genome duplications at the base of the vertebrates have been suggested as enabling the evolution of vertebrate-specific structures such as neural crest, a midbrain/hindbrain organizer and neurogenic placodes. These structures, however, did not evolve entirely de novo, but arose from tissues already present in an ancestral chordate. This review discusses the evolutionary history of co-option of old genes for new roles in vertebrate development as well as the relative contributions of changes in cis-regulation and in protein structure. Particular examples are the FoxD, FGF8/17/18 and Pax2/5/8 genes. Comparisons with invertebrate chordates (amphioxus and tunicates) paint a complex picture with co-option of genes into new structures occurring both after and before the whole genome duplications. In addition, while cis-regulatory changes are likely of primary importance in evolution of vertebrate-specific structures, changes in protein structure including alternative splicing are non-trivial.
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Affiliation(s)
- Linda Z Holland
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093-0202, USA.
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30
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Jidigam VK, Gunhaga L. Development of cranial placodes: insights from studies in chick. Dev Growth Differ 2012; 55:79-95. [PMID: 23278869 DOI: 10.1111/dgd.12027] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Revised: 11/02/2012] [Accepted: 11/03/2012] [Indexed: 12/19/2022]
Abstract
This review focuses on how research, using chick as a model system, has contributed to our knowledge regarding the development of cranial placodes. This review highlights when and how molecular signaling events regulate early specification of placodal progenitor cells, as well as the development of individual placodes including morphological movements. In addition, we briefly describe various techniques used in chick that are important for studies in cell and developmental biology.
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Affiliation(s)
- Vijay K Jidigam
- Umeå Centre for Molecular Medicine, Umeå University, Umeå, Sweden
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31
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Abstract
Despite its complexity in the adult, during development the inner ear arises from a simple epithelium, the otic placode. Placode specification is a multistep process that involves the integration of various signalling pathways and downstream transcription factors in time and space. Here we review the molecular events that successively commit multipotent ectodermal precursors to the otic lineage. The first step in this hierarchy is the specification of sensory progenitor cells, which can contribute to all sensory placodes, followed by the induction of a common otic-epibranchial field and finally the establishment the otic territory. In recent years, some of the molecular components that control this process have been identified, and begin to reveal complex interactions. Future studies will need to unravel how this information is integrated and encoded in the genome. This will form the blueprint for stem cell differentiation towards otic fates and generate a predictive gene regulatory network that models the earliest steps of otic specification.
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Affiliation(s)
- Jingchen Chen
- Department of Craniofacial Development and Stem Cell Biology, King's College London, Guy's Tower Wing, Floor 27, London SE1 9RT, UK
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32
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Grocott T, Tambalo M, Streit A. The peripheral sensory nervous system in the vertebrate head: a gene regulatory perspective. Dev Biol 2012; 370:3-23. [PMID: 22790010 DOI: 10.1016/j.ydbio.2012.06.028] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Revised: 06/28/2012] [Accepted: 06/29/2012] [Indexed: 02/06/2023]
Abstract
In the vertebrate head, crucial parts of the sense organs and sensory ganglia develop from special regions, the cranial placodes. Despite their cellular and functional diversity, they arise from a common field of multipotent progenitors and acquire distinct identity later under the influence of local signalling. Here we present the gene regulatory network that summarises our current understanding of how sensory cells are specified, how they become different from other ectodermal derivatives and how they begin to diversify to generate placodes with different identities. This analysis reveals how sequential activation of sets of transcription factors subdivides the ectoderm over time into smaller domains of progenitors for the central nervous system, neural crest, epidermis and sensory placodes. Within this hierarchy the timing of signalling and developmental history of each cell population is of critical importance to determine the ultimate outcome. A reoccurring theme is that local signals set up broad gene expression domains, which are further refined by mutual repression between different transcription factors. The Six and Eya network lies at the heart of sensory progenitor specification. In a positive feedback loop these factors perpetuate their own expression thus stabilising pre-placodal fate, while simultaneously repressing neural and neural crest specific factors. Downstream of the Six and Eya cassette, Pax genes in combination with other factors begin to impart regional identity to placode progenitors. While our review highlights the wealth of information available, it also points to the lack information on the cis-regulatory mechanisms that control placode specification and of how the repeated use of signalling input is integrated.
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Affiliation(s)
- Timothy Grocott
- Department of Craniofacial Development and Stem Cell Biology, King's College London, Guy's Tower Wing, Floor 27, London SE1 9RT, UK
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33
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Mutual repression between Gbx2 and Otx2 in sensory placodes reveals a general mechanism for ectodermal patterning. Dev Biol 2012; 367:55-65. [PMID: 22564795 PMCID: PMC3384001 DOI: 10.1016/j.ydbio.2012.04.025] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Revised: 04/13/2012] [Accepted: 04/17/2012] [Indexed: 11/27/2022]
Abstract
In the vertebrate head, central and peripheral components of the sensory nervous system have different embryonic origins, the neural plate and sensory placodes. This raises the question of how they develop in register to form functional sense organs and sensory circuits. Here we show that mutual repression between the homeobox transcription factors Gbx2 and Otx2 patterns the placode territory by influencing regional identity and by segregating inner ear and trigeminal progenitors. Activation of Otx2 targets is necessary for anterior olfactory, lens and trigeminal character, while Gbx2 function is required for the formation of the posterior otic placode. Thus, like in the neural plate antagonistic interaction between Otx2 and Gbx2 establishes positional information thus providing a general mechanism for rostro-caudal patterning of the ectoderm. Our findings support the idea that the Otx/Gbx boundary has an ancient evolutionary origin to which different modules were recruited to specify cells of different fates.
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34
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Abstract
During early vertebrate development, the embryonic ectoderm becomes subdivided into neural, neural plate border (border) and epidermal regions. The nervous system is derived from the neural and border domains which, respectively, give rise to the central and peripheral nervous systems. To better understand the functional nervous system we need to know how individual neurons are specified and connected. Our understanding of the early development of the peripheral nervous system has been lagging compared to knowledge regarding central nervous system and epidermal cell lineage decision. Recent advances have shown when and how the specification of border cells is initiated. One important insight is that border specification is already initiated at blastula stages, and can be molecularly and temporally distinguished from rostrocaudal regionalisation of the border. From findings in several species, it is clear that Wnt, Bone Morphogenetic Protein and Fibroblast Growth Factor signals play important roles during the specification and regionalisation of the border. In this review, we highlight the individual roles of these signals and compare models of border specification, including a new model that describes how temporal coordination and epistatic interactions of extracellular signals result in the specification and regionalisation of border cells.
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Affiliation(s)
- Cédric Patthey
- Umeå Centre for Molecular Medicine, Building 6M, 4th Floor, Umeå University, S-901 87 Umeå, Sweden
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35
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Origin and segregation of cranial placodes in Xenopus laevis. Dev Biol 2011; 360:257-75. [PMID: 21989028 DOI: 10.1016/j.ydbio.2011.09.024] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2011] [Revised: 08/31/2011] [Accepted: 09/01/2011] [Indexed: 11/23/2022]
Abstract
Cranial placodes are local thickenings of the vertebrate head ectoderm that contribute to the paired sense organs (olfactory epithelium, lens, inner ear, lateral line), cranial ganglia and the adenohypophysis. Here we use tissue grafting and dye injections to generated fate maps of the dorsal cranial part of the non-neural ectoderm for Xenopus embryos between neural plate and early tailbud stages. We show that all placodes arise from a crescent-shaped area located around the anterior neural plate, the pre-placodal ectoderm. In agreement with proposed roles of Six1 and Pax genes in the specification of a panplacodal primordium and different placodal areas, respectively, we show that Six1 is expressed uniformly throughout most of the pre-placodal ectoderm, while Pax6, Pax3, Pax8 and Pax2 each are confined to specific subregions encompassing the precursors of different subsets of placodes. However, the precursors of the vagal epibranchial and posterior lateral line placodes, which arise from the posteriormost pre-placodal ectoderm, upregulate Six1 and Pax8/Pax2 only at tailbud stages. Whereas our fate map suggests that regions of origin for different placodes overlap extensively with each other and with other ectodermal fates at neural plate stages, analysis of co-labeled placodes reveals that the actual degree of overlap is much smaller. Time lapse imaging of the pre-placodal ectoderm at single cell resolution demonstrates that no directed, large-scale cell rearrangements occur, when the pre-placodal region segregates into distinct placodes at subsequent stages. Our results indicate that individuation of placodes from the pre-placodal ectoderm does not involve large-scale cell sorting in Xenopus.
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36
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Neural crest and ectodermal cells intermix in the nasal placode to give rise to GnRH-1 neurons, sensory neurons, and olfactory ensheathing cells. J Neurosci 2011; 31:6915-27. [PMID: 21543621 DOI: 10.1523/jneurosci.6087-10.2011] [Citation(s) in RCA: 147] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The origin of GnRH-1 cells and olfactory ensheathing cells has been controversial. Genetic Cre-lox lineage tracing of the neural crest (NC) versus ectodermal contribution to the developing nasal placode was performed using two complementary mouse models, the NC-specific Wnt1Cre mouse line and an ectodermal-specific Crect mouse line. Using these lines we prove that the NC give rise to the olfactory ensheathing cells and subpopulations of GnRH-1 neurons, olfactory and vomeronasal cells. These data demonstrate that Schwann cells and olfactory ensheathing cells share a common developmental origin. Furthermore, the results indicate that certain conditions that impact olfaction and sexual development, such as Kallmann syndrome, may be in part neurocristopathies.
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Gitton Y, Benouaiche L, Vincent C, Heude E, Soulika M, Bouhali K, Couly G, Levi G. Dlx5 and Dlx6 expression in the anterior neural fold is essential for patterning the dorsal nasal capsule. Development 2011; 138:897-903. [PMID: 21270050 DOI: 10.1242/dev.057505] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Morphogenesis of the vertebrate facial skeleton depends upon inductive interactions between cephalic neural crest cells (CNCCs) and cephalic epithelia. The nasal capsule is a CNCC-derived cartilaginous structure comprising a ventral midline bar (mesethmoid) overlaid by a dorsal capsule (ectethmoid). Although Shh signalling from the anterior-most region of the endoderm (EZ-I) patterns the mesethmoid, the cues involved in ectethmoid induction are still undefined. Here, we show that ectethmoid formation depends upon Dlx5 and Dlx6 expression in a restricted ectodermal territory of the anterior neural folds, which we name NF-ZA. In both chick and mouse neurulas, Dlx5 and Dlx6 expression is mostly restricted to NF-ZA. Simultaneous Dlx5 and Dlx6 inactivation in the mouse precludes ectethmoid formation, while the mesethmoid is still present. Consistently, siRNA-mediated downregulation of Dlx5 and Dlx6 in the cephalic region of the early avian neurula specifically prevents ectethmoid formation, whereas other CNCC-derived structures, including the mesethmoid, are not affected. Similarly, NF-ZA surgical removal in chick neurulas averts ectethmoid development, whereas grafting a supernumerary NF-ZA results in an ectopic ectethmoid. Simultaneous ablation or grafting of both NF-ZA and EZ-I result, respectively, in the absence or duplication of both dorsal and ventral nasal capsule components. The present work shows that early ectodermal and endodermal signals instruct different contingents of CNCCs to form the ectethmoid and the mesethmoid, which then assemble to form a complete nasal capsule.
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Affiliation(s)
- Yorick Gitton
- Evolution des Régulations Endocriniennes, CNRS UMR 7221, Muséum National d'Histoire Naturelle, Paris, France
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Rawson NE, Lischka FW, Yee KK, Peters AZ, Tucker ES, Meechan DW, Zirlinger M, Maynard TM, Burd GB, Dulac C, Pevny L, LaMantia AS. Specific mesenchymal/epithelial induction of olfactory receptor, vomeronasal, and gonadotropin-releasing hormone (GnRH) neurons. Dev Dyn 2010; 239:1723-38. [PMID: 20503368 DOI: 10.1002/dvdy.22315] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
We asked whether specific mesenchymal/epithelial (M/E) induction generates olfactory receptor neurons (ORNs), vomeronasal neurons (VRNs), and gonadotropin-releasing hormone (GnRH) neurons, the major neuron classes associated with the olfactory epithelium (OE). To assess specificity of M/E-mediated neurogenesis, we compared the influence of frontonasal mesenchyme on frontonasal epithelium, which becomes the OE, with that of the forelimb bud. Despite differences in position, morphogenetic and cytogenic capacity, both mesenchymal tissues support neurogenesis, expression of several signaling molecules and neurogenic transcription factors in the frontonasal epithelium. Only frontonasal mesenchyme, however, supports OE-specific patterning and activity of a subset of signals and factors associated with OE differentiation. Moreover, only appropriate pairing of frontonasal epithelial and mesenchymal partners yields ORNs, VRNs, and GnRH neurons. Accordingly, the position and molecular identity of specialized frontonasal epithelia and mesenchyme early in gestation and subsequent inductive interactions specify the genesis and differentiation of peripheral chemosensory and neuroendocrine neurons.
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Affiliation(s)
- N E Rawson
- Monell Chemical Senses Center, Philadelphia, Pennsylvania, USA
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39
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Embryonic Pax7-expressing progenitors contribute multiple cell types to the postnatal olfactory epithelium. J Neurosci 2010; 30:9523-32. [PMID: 20631180 DOI: 10.1523/jneurosci.0867-10.2010] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Prolonged neurogenesis driven by stem/progenitor cells is a hallmark of the olfactory epithelium (OE), beginning at the placodal stages in the embryo and continuing throughout adult life. Despite the progress made to identify and study the regulation of adult OE progenitors, our knowledge of embryonic OE precursors and their cellular contributions to the adult OE has been stalled by the lack of markers able to distinguish individual candidate progenitors. Here we identify embryonic OE Pax7+ progenitors, detected at embryonic day 10.5 (E10.5) in the olfactory pit with an antigen profile and location previously assigned to presumptive OE stem cells. Using Cre-loxP technology (Pax7-cre/ROSA YFP mice), we expose a wide range of derivatives, including CNS and olfactory neurons, non-neuronal cells, and olfactory ensheathing glia, all made from embryonic Pax7+ cells. Importantly, the expression of Pax7 in the embryonic OE is downregulated from E15.5, such that after birth, no Pax7+ cells are found in the OE, and thus the progenitor population here identified is restricted to embryonic stages. Our results provide the first evidence for a population of Pax7-expressing embryonic progenitors that contribute to multiple OE lineages and demonstrate novel insights into the unique spatiotemporal patterning of the postnatal OE.
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40
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Terakado K. Generation of prolactin-like neurons in the dorsal strand of ascidians. Zoolog Sci 2010; 27:581-8. [PMID: 20608847 DOI: 10.2108/zsj.27.581] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The adult ascidian neural complex forms from a thin tube called the neurohypophyseal duct and from the primordium of the cerebral ganglion from the sensory vesicle in metamorphosing larvae. Neurohypophyseal duct cells, located in the anterior left side of the sensory vesicle of swimming larvae, are derived from the anterior embryonic neural plate, which expresses common transcription factors in vertebrates and urochordates. The cerebral ganglion primordium is probably derived from the posterior sensory vesicle during metamorphosis. After metamorphosis begins, the duct elongates anteriorly and fuses with the stomodeal ectoderm, where the dorsal tubercle, a large ciliated structure that opens into the upper part of the pharynx, later develops. The rudiment of the cerebral ganglion and the duct elongate posteriorly. The duct also differentiates into the neural gland. The dorsal wall of the neural gland in adult ascidians has a thick epithelium (placode), the central part of which forms the dorsal strand by repeated invaginations along the visceral nerve. Both gonadotropin-releasing hormone (GnRH) neurons and prolactin-like (non-GnRH) neurons are generated in the dorsal strand and migrate to the cerebral ganglion along the visceral nerve throughout adulthood. Thus, the epithelium derived from the neurohypophyseal duct possesses neurogenic potential to generate neural stem cells of the central (cerebral ganglion) and peripheral (dorsal strand) nervous systems. The generation of prolactin-like neurons and their migration into the brain with GnRH neurons suggest that the ascidian dorsal strand is homologous to the craniate olfactory placode, and provide unequivocal support for the existence of the clade Olfactores.
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Affiliation(s)
- Kiyoshi Terakado
- Department of Regulation Biology, Faculty of Science, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570, Japan.
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Schlosser G. Making senses development of vertebrate cranial placodes. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2010; 283:129-234. [PMID: 20801420 DOI: 10.1016/s1937-6448(10)83004-7] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Cranial placodes (which include the adenohypophyseal, olfactory, lens, otic, lateral line, profundal/trigeminal, and epibranchial placodes) give rise to many sense organs and ganglia of the vertebrate head. Recent evidence suggests that all cranial placodes may be developmentally related structures, which originate from a common panplacodal primordium at neural plate stages and use similar regulatory mechanisms to control developmental processes shared between different placodes such as neurogenesis and morphogenetic movements. After providing a brief overview of placodal diversity, the present review summarizes current evidence for the existence of a panplacodal primordium and discusses the central role of transcription factors Six1 and Eya1 in the regulation of processes shared between different placodes. Upstream signaling events and transcription factors involved in early embryonic induction and specification of the panplacodal primordium are discussed next. I then review how individual placodes arise from the panplacodal primordium and present a model of multistep placode induction. Finally, I briefly summarize recent advances concerning how placodal neurons and sensory cells are specified, and how morphogenesis of placodes (including delamination and migration of placode-derived cells and invagination) is controlled.
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Affiliation(s)
- Gerhard Schlosser
- Zoology, School of Natural Sciences & Martin Ryan Institute, National University of Ireland, Galway, Ireland
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42
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Molecular and tissue interactions governing induction of cranial ectodermal placodes. Dev Biol 2009; 332:189-95. [PMID: 19500565 DOI: 10.1016/j.ydbio.2009.05.572] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2009] [Revised: 05/27/2009] [Accepted: 05/28/2009] [Indexed: 12/31/2022]
Abstract
Whereas neural crest cells are the source of the peripheral nervous system in the trunk of vertebrates, the "ectodermal placodes," together with neural crest, form the peripheral nervous system of the head. Cranial ectodermal placodes are thickenings in the ectoderm that subsequently ingress or invaginate to make important contributions to cranial ganglia, including epibranchial and trigeminal ganglia, and sensory structures, the ear, nose, lens, and adenohypophysis. Recent studies have uncovered a number of molecular signals mediating induction and differentiation of placodal cells. Here, we described recent advances in understanding the tissue interactions and signals underlying induction and neurogenesis of placodes, with emphasis on the trigeminal and epibranchial. Important roles of Fibroblast Growth Factors, Platelet Derived Growth Factors, Sonic Hedgehog, TGFbeta superfamily members, and Wnts are discussed.
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Szabo-Rogers HL, Geetha-Loganathan P, Whiting CJ, Nimmagadda S, Fu K, Richman JM. Novel skeletogenic patterning roles for the olfactory pit. Development 2008; 136:219-29. [PMID: 19056832 DOI: 10.1242/dev.023978] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The position of the olfactory placodes suggests that these epithelial thickenings might provide morphogenetic information to the adjacent facial mesenchyme. To test this, we performed in ovo manipulations of the nasal placode in the avian embryo. Extirpation of placodal epithelium or placement of barriers on the lateral side of the placode revealed that the main influence is on the lateral nasal, not the frontonasal, mesenchyme. These early effects were consistent with the subsequent deletion of lateral nasal skeletal derivatives. We then showed in rescue experiments that FGFs are required for nasal capsule morphogenesis. The instructive capacity of the nasal pit epithelium was tested in a series of grafts to the face and trunk. Here, we showed for the first time that nasal pits are capable of inducing bone, cartilage and ectopic PAX7 expression, but these effects were only observed in the facial grafts. Facial mesenchyme also supported the initial projection of the olfactory nerve and differentiation of the olfactory epithelium. Thus, the nasal placode has two roles: as a signaling center for the lateral nasal skeleton and as a source of olfactory neurons and sensory epithelium.
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Affiliation(s)
- Heather L Szabo-Rogers
- Department of Oral Health Sciences, Life Sciences Institute, The University of British Columbia, Vancouver BC, V6T 1Z3, Canada
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