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Flach H, Brendler C, Schöpf M, Xu L, Schneider J, Dewald K, Dietmann P, Kühl M, Kühl SJ. Comparing the effects of three neonicotinoids on embryogenesis of the South African clawed frog Xenopus laevis. Curr Res Toxicol 2024; 6:100169. [PMID: 38706785 PMCID: PMC11068530 DOI: 10.1016/j.crtox.2024.100169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 04/16/2024] [Accepted: 04/18/2024] [Indexed: 05/07/2024] Open
Abstract
Neonicotinoids (NEOs) are widely used insecticides that are ubiquitous in agricultural use. Since NEOs are found in natural waters as well as in tap water and human urine in regions where NEOs are widely used, NEOs pose a potential hazard to non-target organisms such as animals and humans. Some of the commonly detected NEOs are imidacloprid (IMD), thiamethoxam (TMX), and its metabolite clothianidin (CLO). Although previously published scientific information, including an assessment of the environmental risks, particularly for bees, had resulted in a ban on the outdoor use of these three NEOs in the EU - their use is now only permitted in closed greenhouses - these NEOs continue to be used in agriculture in many other parts of the world. Therefore, a detailed study and comparison of the effects of NEOs on the embryonic development of non-target organisms is needed to further define the risk profiles. Embryos of the South African clawed frog Xenopus laevis, a well-established aquatic model, were exposed to different concentrations of IMD, TMX, or CLO (0.1-100 mg/L) to study and compare the possible effects of a single contaminant in natural water bodies on early embryogenesis. The results included a reduced body length, a smaller orbital space, impaired cranial cartilage and nerves, and an altered heart structure and function. At the molecular level, NEO exposure partially resulted in an altered expression of tissue-specific factors, which are involved in eye, cranial placode, and heart development. Our results suggest that the NEOs studied negatively affect the embryonic development of the non-target organism X. laevis. Since pesticides, especially NEOs, pollute the environment worldwide, it is suggested that they are strictly controlled and monitored in the areas where they are used. In addition, the question arises as to whether pesticide metabolites also pose a risk to the environment and need to be investigated further so that they can be taken into account when registering ingredients.
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Affiliation(s)
| | | | - Martina Schöpf
- Institute of Biochemistry and Molecular Biology, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, German
| | - Lilly Xu
- Institute of Biochemistry and Molecular Biology, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, German
| | - Julia Schneider
- Institute of Biochemistry and Molecular Biology, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, German
| | - Kathrin Dewald
- Institute of Biochemistry and Molecular Biology, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, German
| | - Petra Dietmann
- Institute of Biochemistry and Molecular Biology, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, German
| | - Michael Kühl
- Institute of Biochemistry and Molecular Biology, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, German
| | - Susanne J. Kühl
- Institute of Biochemistry and Molecular Biology, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, German
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2
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Griffin C, Saint-Jeannet JP. In vitro modeling of cranial placode differentiation: Recent advances, challenges, and perspectives. Dev Biol 2024; 506:20-30. [PMID: 38052294 PMCID: PMC10843546 DOI: 10.1016/j.ydbio.2023.11.009] [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: 05/26/2023] [Revised: 11/27/2023] [Accepted: 11/29/2023] [Indexed: 12/07/2023]
Abstract
Cranial placodes are transient ectodermal thickenings that contribute to a diverse array of organs in the vertebrate head. They develop from a common territory, the pre-placodal region that over time segregates along the antero-posterior axis into individual placodal domains: the adenohypophyseal, olfactory, lens, trigeminal, otic, and epibranchial placodes. These placodes terminally differentiate into the anterior pituitary, the lens, and contribute to sensory organs including the olfactory epithelium, and inner ear, as well as several cranial ganglia. To study cranial placodes and their derivatives and generate cells for therapeutic purposes, several groups have turned to in vitro derivation of placodal cells from human embryonic stem cells (hESCs) or induced pluripotent stem cells (hiPSCs). In this review, we summarize the signaling cues and mechanisms involved in cranial placode induction, specification, and differentiation in vivo, and discuss how this knowledge has informed protocols to derive cranial placodes in vitro. We also discuss the benefits and limitations of these protocols, and the potential of in vitro cranial placode modeling in regenerative medicine to treat cranial placode-related pathologies.
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Affiliation(s)
- Casey Griffin
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, NY, 10010, USA
| | - Jean-Pierre Saint-Jeannet
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, NY, 10010, USA.
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3
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Yamamoto T, Kambayashi Y, Tsukano K, Michiue T. Ndst1, a heparan sulfate modification enzyme, regulates neuroectodermal patterning by enhancing Wnt signaling in Xenopus. Dev Growth Differ 2023; 65:153-160. [PMID: 36726238 DOI: 10.1111/dgd.12843] [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: 06/13/2022] [Revised: 01/05/2023] [Accepted: 01/10/2023] [Indexed: 02/03/2023]
Abstract
Neural tissue is derived from three precursor regions: neural plate, neural crest, and preplacodal ectoderm. These regions are determined by morphogen-mediated signaling. Morphogen distribution is generally regulated by binding to an extracellular matrix component, heparan sulfate (HS) proteoglycan. HS is modified by many enzymes, such as N-deacetyl sulfotransferase 1 (Ndst1), which is highly expressed in early development. However, functions of HS modifications in ectodermal patterning are largely unknown. In this study, we analyzed the role of Ndst1 using Xenopus embryos. We found that ndst1 was expressed in anterior neural plate and the trigeminal region at the neurula stage. ndst1 overexpression expanded the neural crest (NC) region, whereas translational inhibition reduced not only the trigeminal region, but also the adjacent NC region, especially the anterior part. At a later stage, ndst1 knocked-down embryos showed defects in cranial ganglion formation. We also found that Ndst1 activates Wnt signaling pathway at the neurula stage. Taken together, our results suggest that N-sulfonated HS accumulates Wnt ligand and activates Wnt signaling in ndst1-expressing cells, but that it inhibits signaling in non-ndst1-expressing cells, leading to proper neuroectodermal patterning.
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Affiliation(s)
- Takayoshi Yamamoto
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
| | - Yuta Kambayashi
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
| | - Kohei Tsukano
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan
| | - Tatsuo Michiue
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan.,Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, Japan
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Tan AL, Mohanty S, Guo J, Lekven AC, Riley BB. Pax2a, Sp5a and Sp5l act downstream of Fgf and Wnt to coordinate sensory-neural patterning in the inner ear. Dev Biol 2022; 492:139-153. [PMID: 36244503 DOI: 10.1016/j.ydbio.2022.10.004] [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: 07/22/2022] [Revised: 09/25/2022] [Accepted: 10/10/2022] [Indexed: 01/21/2023]
Abstract
In zebrafish, sensory epithelia and neuroblasts of the inner ear form simultaneously in abutting medial and lateral domains, respectively, in the floor of the otic vesicle. Previous studies support regulatory roles for Fgf and Wnt, but how signaling is coordinated is poorly understood. We investigated this problem using pharmacological and transgenic methods to alter Fgf or Wnt signaling from early placodal stages to evaluate later changes in growth and patterning. Blocking Fgf at any stage reduces proliferation of otic tissue and terminates both sensory and neural specification. Wnt promotes proliferation in the otic vesicle but is not required for sensory or neural development. However, sustained overactivation of Wnt laterally expands sensory epithelia and blocks neurogenesis. pax2a, sp5a and sp5l are coregulated by Fgf and Wnt and show overlapping expression in the otic placode and vesicle. Gain- and loss-of-function studies show that these genes are together required for Wnt's suppression of neurogenesis, as well as some aspects of sensory development. Thus, pax2a, sp5a and sp5l are critical for mediating Fgf and Wnt signaling to promote spatially localized sensory and neural development.
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Affiliation(s)
- Amy L Tan
- Biology Department, Texas A&M University, College Station, TX, United States
| | - Saurav Mohanty
- Department of Biology and Biochemistry, University of Houston, Houston, TX, United States
| | - Jinbai Guo
- Biology Department, Texas A&M University, College Station, TX, United States
| | - Arne C Lekven
- Department of Biology and Biochemistry, University of Houston, Houston, TX, United States
| | - Bruce B Riley
- Biology Department, Texas A&M University, College Station, TX, United States.
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Bricker RL, Bhaskar U, Titone R, Carless MA, Barberi T. A Molecular Analysis of Neural Olfactory Placode Differentiation in Human Pluripotent Stem Cells. Stem Cells Dev 2022; 31:507-520. [PMID: 35592997 PMCID: PMC9641992 DOI: 10.1089/scd.2021.0257] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Accepted: 05/19/2022] [Indexed: 11/12/2022] Open
Abstract
During embryonic development, the olfactory sensory neurons (OSNs) and the gonadotropic-releasing hormone neurons (GNRHNs) migrate from the early nasal cavity, known as the olfactory placode, to the brain. Defects in the development of OSNs and GNRHNs result in neurodevelopmental disorders such as anosmia and congenital hypogonadotropic hypogonadism, respectively. Treatments do not restore the defective neurons in these disorders, and as a result, patients have a diminished sense of smell or a gonadotropin hormone deficiency. Human pluripotent stem cells (hPSCs) can produce any cell type in the body; therefore, they are an invaluable tool for cell replacement therapies. Transplantation of olfactory placode progenitors, derived from hPSCs, is a promising therapeutic to replace OSNs and GNRHNs and restore tissue function. Protocols to generate olfactory placode progenitors are limited, and thus, we describe, in this study, a novel in vitro model for olfactory placode differentiation in hPSCs, which is capable of producing both OSNs and GNRHNs. Our study investigates the major developmental signaling factors that recapitulate the embryonic development of the olfactory tissue. We demonstrate that induction of olfactory placode in hPSCs requires bone morphogenetic protein inhibition, wingless/integrated protein inhibition, retinoic acid inhibition, transforming growth factor alpha activation, and fibroblast growth factor 8 activation. We further show that the protocol transitions hPSCs through the anterior pan-placode ectoderm and neural ectoderm regions in early development while preventing neural crest and non-neural ectoderm regions. Finally, we demonstrate production of OSNs and GNRHNs by day 30 of differentiation. Our study is the first to report on OSN differentiation in hPSCs.
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Affiliation(s)
- Rebecca L. Bricker
- Population Health Program, Texas Biomedical Research Institute, San Antonio, Texas, USA
- Department of Cell Systems and Anatomy, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
| | - Uchit Bhaskar
- Department of Neuroscience, Developmental and Regenerative Biology, University of Texas at San Antonio, San Antonio, Texas, USA
| | - Rossella Titone
- Population Health Program, Texas Biomedical Research Institute, San Antonio, Texas, USA
| | - Melanie A. Carless
- Population Health Program, Texas Biomedical Research Institute, San Antonio, Texas, USA
- Department of Cell Systems and Anatomy, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
- Department of Neuroscience, Developmental and Regenerative Biology, University of Texas at San Antonio, San Antonio, Texas, USA
| | - Tiziano Barberi
- Population Health Program, Texas Biomedical Research Institute, San Antonio, Texas, USA
- Department of Cell Systems and Anatomy, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
- Lab Farm Foods, Inc., New York City, New York, USA
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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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Saeki T, Yoshimatsu S, Ishikawa M, Hon CC, Koya I, Shibata S, Hosoya M, Saegusa C, Ogawa K, Shin JW, Fujioka M, Okano H. Critical roles of FGF, RA, and WNT signalling in the development of the human otic placode and subsequent lineages in a dish. Regen Ther 2022; 20:165-186. [PMID: 35620640 PMCID: PMC9114627 DOI: 10.1016/j.reth.2022.04.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 04/19/2022] [Accepted: 04/26/2022] [Indexed: 11/30/2022] Open
Abstract
Introduction Efficient induction of the otic placode, the developmental origin of the inner ear from human pluripotent stem cells (hPSCs), provides a robust platform for otic development and sensorineural hearing loss modelling. Nevertheless, there remains a limited capacity of otic lineage specification from hPSCs by stepwise differentiation methods, since the critical factors for successful otic cell differentiation have not been thoroughly investigated. In this study, we developed a novel differentiation system involving the use of a three-dimensional (3D) floating culture with signalling factors for generating otic cell lineages via stepwise differentiation of hPSCs. Methods We differentiated hPSCs into preplacodal cells under a two-dimensional (2D) monolayer culture. Then, we transferred the induced preplacodal cells into a 3D floating culture under the control of the fibroblast growth factor (FGF), bone morphogenetic protein (BMP), retinoic acid (RA) and WNT signalling pathways. We evaluated the characteristics of the induced cells using immunocytochemistry, quantitative PCR (qPCR), population averaging, and single-cell RNA-seq (RNA-seq) analysis. We further investigated the methods for differentiating otic progenitors towards hair cells by overexpression of defined transcription factors. Results We demonstrated that hPSC-derived preplacodal cells acquired the potential to differentiate into posterior placodal cells in 3D floating culture with FGF2 and RA. Subsequent activation of WNT signalling induced otic placodal cell formation. By single-cell RNA-seq (scRNA-seq) analysis, we identified multiple clusters of otic placode- and otocyst marker-positive cells in the induced spheres. Moreover, the induced otic cells showed the potential to generate hair cell-like cells by overexpression of the transcription factors ATOH1, POU4F3 and GFI1. Conclusions We demonstrated the critical role of FGF2, RA and WNT signalling in a 3D environment for the in vitro differentiation of otic lineage cells from hPSCs. The induced otic cells had the capacity to differentiate into inner ear hair cells with stereociliary bundles and tip link-like structures. The protocol will be useful for in vitro disease modelling of sensorineural hearing loss and human inner ear development and thus contribute to drug screening and stem cell-based regenerative medicine. A 3D floating culture condition is critical for inducing otic placodal cells from hPSCs-derived preplacodal cells. Activation of FGF, RA, WNT signalling pathways is indispensable for differentiating otic lineage under the 3D condition. Overexpression of defined transcription factors facilitated the generation of hair cells from hPSCs-derived otic cells.
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8
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Kano M, Sasaki H, Miwata T, Suga H. Recipe for pituitary organoids. Front Endocrinol (Lausanne) 2022; 13:1025825. [PMID: 36743928 PMCID: PMC9892717 DOI: 10.3389/fendo.2022.1025825] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 12/15/2022] [Indexed: 01/20/2023] Open
Abstract
Generation of a variety of organs and tissues from human pluripotent stem cells (hPSCs) has been attempted in vitro. We here present a simple and efficient method for induction of hypothalamic and pituitary tissues from hPSCs. On provision of exogenous agents important for early hypothalamus-pituitary organogenesis, including bone morphogenetic protein 4 and activators of sonic hedgehog, in three-dimensional culture, hPSCs spontaneously form spherical organoids with two distinct tissues, hypothalamus and adenohypophysis. The pituitary tissues derived from hPSCs not only secrete adenocorticotropic hormone, but also retain both positive and negative feedback mechanisms, recapitulating mature endocrine organs in vivo. Furthermore, the results of ectopic transplantation with mouse models of hypopituitarism suggest that these hypothalamus-pituitary organoids have potential as engraftment organs. In addition to their use in transplantation for patients with hypopituitarism they will allow establishment of disease models in vitro and enable research impossible in humans. Hypothalamus-pituitary organoids promise to be a powerful tool in regenerative medicine, drug discovery, and basic research into pituitary development.
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Affiliation(s)
- Mayuko Kano
- Division of Metabolism and Endocrinology, Department of Internal Medicine, St. Marianna University School of Medicine, Kanagawa, Japan
- *Correspondence: Mayuko Kano, ; Hidetaka Suga,
| | - Hiroo Sasaki
- Department of Neurosurgery, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Tsutomu Miwata
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hidetaka Suga
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
- *Correspondence: Mayuko Kano, ; Hidetaka Suga,
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9
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Mackowetzky K, Yoon KH, Mackowetzky EJ, Waskiewicz AJ. Development and evolution of the vestibular apparatuses of the inner ear. J Anat 2021; 239:801-828. [PMID: 34047378 PMCID: PMC8450482 DOI: 10.1111/joa.13459] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 04/07/2021] [Accepted: 05/06/2021] [Indexed: 12/16/2022] Open
Abstract
The vertebrate inner ear is a labyrinthine sensory organ responsible for perceiving sound and body motion. While a great deal of research has been invested in understanding the auditory system, a growing body of work has begun to delineate the complex developmental program behind the apparatuses of the inner ear involved with vestibular function. These animal studies have helped identify genes involved in inner ear development and model syndromes known to include vestibular dysfunction, paving the way for generating treatments for people suffering from these disorders. This review will provide an overview of known inner ear anatomy and function and summarize the exciting discoveries behind inner ear development and the evolution of its vestibular apparatuses.
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Affiliation(s)
- Kacey Mackowetzky
- Department of Biological SciencesUniversity of AlbertaEdmontonAlbertaCanada
| | - Kevin H. Yoon
- Department of Biological SciencesUniversity of AlbertaEdmontonAlbertaCanada
| | | | - Andrew J. Waskiewicz
- Department of Biological SciencesUniversity of AlbertaEdmontonAlbertaCanada
- Women & Children’s Health Research InstituteUniversity of AlbertaEdmontonAlbertaCanada
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10
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Tambalo M, Anwar M, Ahmed M, Streit A. Enhancer activation by FGF signalling during otic induction. Dev Biol 2020; 457:69-82. [PMID: 31539539 PMCID: PMC6902270 DOI: 10.1016/j.ydbio.2019.09.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 09/16/2019] [Accepted: 09/16/2019] [Indexed: 02/07/2023]
Abstract
Vertebrate ear progenitors are induced by fibroblast growth factor signalling, however the molecular mechanisms leading to the coordinate activation of downstream targets are yet to be discovered. The ear, like other sensory placodes, arises from the pre-placodal region at the border of the neural plate. Using a multiplex NanoString approach, we determined the response of these progenitors to FGF signalling by examining the changes of more than 200 transcripts that define the otic and other placodes, neural crest and neural plate territories. This analysis identifies new direct and indirect FGF targets during otic induction. Investigating changes in histone marks by ChIP-seq reveals that FGF exposure of pre-placodal cells leads to rapid deposition of active chromatin marks H3K27ac near FGF-response genes, while H3K27ac is depleted in the vicinity of non-otic genes. Genomic regions that gain H3K27ac act as cis-regulatory elements controlling otic gene expression in time and space and define a unique transcription factor signature likely to control their activity. Finally, we show that in response to FGF signalling the transcription factor dimer AP1 recruits the histone acetyl transferase p300 to selected otic enhancers. Thus, during ear induction FGF signalling modifies the chromatin landscape to promote enhancer activation and chromatin accessibility.
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Affiliation(s)
- Monica Tambalo
- Centre for Craniofacial and Regenerative Biology, Faculty of Dental, Oral and Craniofacial Sciences, King's College London, London, SE1 9RT, UK
| | - Maryam Anwar
- Centre for Craniofacial and Regenerative Biology, Faculty of Dental, Oral and Craniofacial Sciences, King's College London, London, SE1 9RT, UK
| | - Mohi Ahmed
- Centre for Craniofacial and Regenerative Biology, Faculty of Dental, Oral and Craniofacial Sciences, King's College London, London, SE1 9RT, UK
| | - Andrea Streit
- Centre for Craniofacial and Regenerative Biology, Faculty of Dental, Oral and Craniofacial Sciences, King's College London, London, SE1 9RT, UK.
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11
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Cerio DG, Witmer LM. Intraspecific variation and symmetry of the inner-ear labyrinth in a population of wild turkeys: implications for paleontological reconstructions. PeerJ 2019; 7:e7355. [PMID: 31372322 PMCID: PMC6659666 DOI: 10.7717/peerj.7355] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 06/26/2019] [Indexed: 12/25/2022] Open
Abstract
The cochlea and semicircular canals (SCCs) of the inner ear are vital neurosensory devices. There are associations between the anatomy of these sensorineural structures, their function, and the function of related biological systems, for example, hearing ability, gaze stabilization, locomotor agility, and posture. The endosseous labyrinth is frequently used as a proxy to infer the performance of the hearing and vestibular systems, locomotor abilities, and ecology of extinct species. Such fossil inferences are often based on single specimens or even a single ear, representing an entire species. To address whether a single ear is representative of a population, we used geometric morphometrics to quantitatively assess the variation in shape and symmetry in a sample of endosseous labyrinths of wild turkeys Meleagris gallopavo of southern Ohio. We predicted that ears would be symmetrical both within individuals and across the sample; that labyrinth shape and size would covary; that labyrinth shape would vary with the size of the brain, measured as width of the endocranium at the cerebellum; and that labyrinths would be morphologically integrated. To test these predictions, we microCT-scanned the heads of 26 cadaveric turkeys, digitally segmented their endosseous labyrinths in Avizo, and assigned 15 manual landmarks and 20 sliding semilandmarks to each digital model. Following Procrustes alignment, we conducted an analysis of bilateral symmetry, a Procrustes regression analysis for allometry and other covariates including side and replicate, and analyses of global integration and modularity. Based on Procrustes distances, no individual’s left and right ears were clearly different from each other. When comparing the ears of different specimens, statistically clear differences in shape were found in only 66 of more than 1,300 contrasts. Moreover, effects of both directional and fluctuating asymmetry were very small—generally, two orders of magnitude smaller than the variance explained by individual variation. Statistical tests disagreed on whether these asymmetric effects crossed the threshold of significance, possibly due to non-isotropic variation among landmarks. Regardless, labyrinths appeared to primarily vary in shape symmetrically. Neither labyrinth size nor endocranial width was correlated with labyrinth shape, contrary to our expectations. Finally, labyrinths were found to be moderately integrated in a global sense, but four weakly separated modules—the three SCCs and cochlea—were recovered using a maximum-likelihood analysis. The results show that both fluctuating and directional asymmetry play a larger role in shape variation than expected—but nonetheless, endosseous labyrinths are symmetrical within individuals and at the level of the population, and their shape varies symmetrically. Thus, inferences about populations, and very possibly species, may be confidently made when only a single specimen, or even a single ear, is available for study.
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Affiliation(s)
- Donald G Cerio
- Department of Biological Sciences, Ohio University, Athens, OH, USA.,Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, USA
| | - Lawrence M Witmer
- Department of Biomedical Sciences, Heritage College of Osteopathic Medicine, Ohio University, Athens, OH, USA
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12
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Devotta A, Hong CS, Saint-Jeannet JP. Dkk2 promotes neural crest specification by activating Wnt/β-catenin signaling in a GSK3β independent manner. eLife 2018; 7:34404. [PMID: 30035713 PMCID: PMC6056231 DOI: 10.7554/elife.34404] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 07/06/2018] [Indexed: 11/13/2022] Open
Abstract
Neural crest progenitors are specified through the modulation of several signaling pathways, among which the activation of Wnt/β-catenin signaling by Wnt8 is especially critical. Glycoproteins of the Dickkopf (Dkk) family are important modulators of Wnt signaling acting primarily as Wnt antagonists. Here we report that Dkk2 is required for neural crest specification functioning as a positive regulator of Wnt/β-catenin signaling. Dkk2 depletion in Xenopus embryos causes a loss of neural crest progenitors, a phenotype that is rescued by expression of Lrp6 or β-catenin. Dkk2 overexpression expands the neural crest territory in a pattern reminiscent of Wnt8, Lrp6 and β-catenin gain-of-function phenotypes. Mechanistically, we show that Dkk2 mediates its neural crest-inducing activity through Lrp6 and β-catenin, however unlike Wnt8, in a GSK3β independent manner. These findings suggest that Wnt8 and Dkk2 converge on β-catenin using distinct transduction pathways both independently required to activate Wnt/β-catenin signaling and induce neural crest cells.
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Affiliation(s)
- Arun Devotta
- Department of Basic Science and Craniofacial Biology, College of Dentistry, New York University, New York, United States
| | - Chang-Soo Hong
- Department of Basic Science and Craniofacial Biology, College of Dentistry, New York University, New York, United States.,Department of Biological Sciences, Daegu University, Gyeongsan, Republic of Korea
| | - Jean-Pierre Saint-Jeannet
- Department of Basic Science and Craniofacial Biology, College of Dentistry, New York University, New York, United States
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13
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Ahmed M, Streit A. Lsd1 interacts with cMyb to demethylate repressive histone marks and maintain inner ear progenitor identity. Development 2018; 145:dev.160325. [PMID: 29437831 DOI: 10.1242/dev.160325] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2017] [Accepted: 01/20/2018] [Indexed: 01/30/2023]
Abstract
During development, multipotent progenitor cells must maintain their identity while retaining the competence to respond to new signalling cues that drive cell fate decisions. This depends on both DNA-bound transcription factors and surrounding histone modifications. Here, we identify the histone demethylase Lsd1 as a crucial component of the molecular machinery that preserves progenitor identity in the developing ear prior to lineage commitment. Although Lsd1 is mainly associated with repressive complexes, we show that, in ear precursors, it is required to maintain active transcription of otic genes. We reveal a novel interaction between Lsd1 and the transcription factor cMyb, which in turn recruits Lsd1 to the promoters of key ear transcription factors. Here, Lsd1 prevents the accumulation of repressive H3K9me2, while allowing H3K9 acetylation. Loss of Lsd1 function causes rapid silencing of active promoters and loss of ear progenitor genes, and shuts down the entire ear developmental programme. Our data suggest that Lsd1-cMyb acts as a co-activator complex that maintains a regulatory module at the top of the inner ear gene network.
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Affiliation(s)
- Mohi Ahmed
- Centre for Craniofacial and Regenerative Biology, Floor 27 Tower Wing, Guy's Hospital, Dental Institute, King's College London, London SE1 9RT, UK
| | - Andrea Streit
- Centre for Craniofacial and Regenerative Biology, Floor 27 Tower Wing, Guy's Hospital, Dental Institute, King's College London, London SE1 9RT, UK
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14
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Gou Y, Guo J, Maulding K, Riley BB. sox2 and sox3 cooperate to regulate otic/epibranchial placode induction in zebrafish. Dev Biol 2018; 435:84-95. [PMID: 29355522 DOI: 10.1016/j.ydbio.2018.01.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 01/15/2018] [Accepted: 01/15/2018] [Indexed: 12/16/2022]
Abstract
Expression of sox3 is one of the earliest markers of Fgf-dependent otic/epibranchial placode induction. We report here that sox2 is also expressed in the early otic/epibranchial placode in zebrafish. To address functions of sox2 and sox3, we generated knockouts and heat shock-inducible transgenes. Mutant analysis, and low-level misexpression, showed that sox2 and sox3 act redundantly to establish a full complement of otic/epibranchial cells. Disruption of pax8, another early regulator, caused similar placodal deficiencies to sox3 mutants or pax8-sox3 double mutants, suggesting that sox3 and pax8 operate in the same pathway. High-level misexpression of sox2 or sox3 during early stages cell-autonomously blocked placode induction, whereas misexpression several hours later could not reverse placodal differentiation. In an assay for ectopic placode-induction, we previously showed that misexpression of fgf8 induces a high level of ectopic sox3, but not pax8. Partial knockdown of sox3 significantly enhanced ectopic induction of pax8, whereas full knockdown of sox3 inhibited this process. Together these findings show that sox2 and sox3 are together required for proper otic induction, but the level of expression must be tightly regulated to avoid suppression of differentiation and maintenance of pluripotency.
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Affiliation(s)
- Yunzi Gou
- Department of Biology, Texas A&M University, College Station, TX 77843-3258, United States
| | - Jinbai Guo
- Department of Biology, Texas A&M University, College Station, TX 77843-3258, United States
| | - Kirstin Maulding
- Department of Biology, Texas A&M University, College Station, TX 77843-3258, United States
| | - Bruce B Riley
- Department of Biology, Texas A&M University, College Station, TX 77843-3258, United States.
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15
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Simon E, Thézé N, Fédou S, Thiébaud P, Faucheux C. Vestigial-like 3 is a novel Ets1 interacting partner and regulates trigeminal nerve formation and cranial neural crest migration. Biol Open 2017; 6:1528-1540. [PMID: 28870996 PMCID: PMC5665465 DOI: 10.1242/bio.026153] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Drosophila Vestigial is the founding member of a protein family containing a highly conserved domain, called Tondu, which mediates their interaction with members of the TEAD family of transcription factors (Scalloped in Drosophila). In Drosophila, the Vestigial/Scalloped complex controls wing development by regulating the expression of target genes through binding to MCAT sequences. In vertebrates, there are four Vestigial-like genes, the functions of which are still not well understood. Here, we describe the regulation and function of vestigial-like 3 (vgll3) during Xenopus early development. A combination of signals, including FGF8, Wnt8a, Hoxa2, Hoxb2 and retinoic acid, limits vgll3 expression to hindbrain rhombomere 2. We show that vgll3 regulates trigeminal placode and nerve formation and is required for normal neural crest development by affecting their migration and adhesion properties. At the molecular level, vgll3 is a potent activator of pax3, zic1, Wnt and FGF, which are important for brain patterning and neural crest cell formation. Vgll3 interacts in the embryo with Tead proteins but unexpectedly with Ets1, with which it is able to stimulate a MCAT driven luciferase reporter gene. Our findings highlight a critical function for vgll3 in vertebrate early development.
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Affiliation(s)
- Emilie Simon
- Univ. Bordeaux, INSERM U1035, F-33076 Bordeaux, France
| | - Nadine Thézé
- Univ. Bordeaux, INSERM U1035, F-33076 Bordeaux, France
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16
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Suzuki A, Yoshida H, van Heeringen SJ, Takebayashi-Suzuki K, Veenstra GJC, Taira M. Genomic organization and modulation of gene expression of the TGF-β and FGF pathways in the allotetraploid frog Xenopus laevis. Dev Biol 2017; 426:336-359. [DOI: 10.1016/j.ydbio.2016.09.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 06/10/2016] [Accepted: 09/19/2016] [Indexed: 12/13/2022]
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17
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Chen J, Tambalo M, Barembaum M, Ranganathan R, Simões-Costa M, Bronner ME, Streit A. A systems-level approach reveals new gene regulatory modules in the developing ear. Development 2017; 144:1531-1543. [PMID: 28264836 PMCID: PMC5399671 DOI: 10.1242/dev.148494] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 02/24/2017] [Indexed: 01/23/2023]
Abstract
The inner ear is a complex vertebrate sense organ, yet it arises from a simple epithelium, the otic placode. Specification towards otic fate requires diverse signals and transcriptional inputs that act sequentially and/or in parallel. Using the chick embryo, we uncover novel genes in the gene regulatory network underlying otic commitment and reveal dynamic changes in gene expression. Functional analysis of selected transcription factors reveals the genetic hierarchy underlying the transition from progenitor to committed precursor, integrating known and novel molecular players. Our results not only characterize the otic transcriptome in unprecedented detail, but also identify new gene interactions responsible for inner ear development and for the segregation of the otic lineage from epibranchial progenitors. By recapitulating the embryonic programme, the genes and genetic sub-circuits discovered here might be useful for reprogramming naïve cells towards otic identity to restore hearing loss. Summary: Transcriptome analysis and knock down of select transcription factors reveals a genetic hierarchy as cells become committed to inner ear fate.
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Affiliation(s)
- Jingchen Chen
- Department of Craniofacial Development and Stem Cell Biology, King's College London, London SE1 9RT, UK
| | - Monica Tambalo
- Department of Craniofacial Development and Stem Cell Biology, King's College London, London SE1 9RT, UK
| | - Meyer Barembaum
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Ramya Ranganathan
- Department of Craniofacial Development and Stem Cell Biology, King's College London, London SE1 9RT, UK
| | - Marcos Simões-Costa
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Marianne E Bronner
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Andrea Streit
- Department of Craniofacial Development and Stem Cell Biology, King's College London, London SE1 9RT, UK
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18
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Matsuoka AJ, Morrissey ZD, Zhang C, Homma K, Belmadani A, Miller CA, Chadly DM, Kobayashi S, Edelbrock AN, Tanaka‐Matakatsu M, Whitlon DS, Lyass L, McGuire TL, Stupp SI, Kessler JA. Directed Differentiation of Human Embryonic Stem Cells Toward Placode-Derived Spiral Ganglion-Like Sensory Neurons. Stem Cells Transl Med 2017; 6:923-936. [PMID: 28186679 PMCID: PMC5442760 DOI: 10.1002/sctm.16-0032] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Revised: 08/31/2016] [Accepted: 10/19/2016] [Indexed: 12/15/2022] Open
Abstract
The ability to generate spiral ganglion neurons (SGNs) from stem cells is a necessary prerequisite for development of cell-replacement therapies for sensorineural hearing loss. We present a protocol that directs human embryonic stem cells (hESCs) toward a purified population of otic neuronal progenitors (ONPs) and SGN-like cells. Between 82% and 95% of these cells express SGN molecular markers, they preferentially extend neurites to the cochlear nucleus rather than nonauditory nuclei, and they generate action potentials. The protocol follows an in vitro stepwise recapitulation of developmental events inherent to normal differentiation of hESCs into SGNs, resulting in efficient sequential generation of nonneuronal ectoderm, preplacodal ectoderm, early prosensory ONPs, late ONPs, and cells with cellular and molecular characteristics of human SGNs. We thus describe the sequential signaling pathways that generate the early and later lineage species in the human SGN lineage, thereby better describing key developmental processes. The results indicate that our protocol generates cells that closely replicate the phenotypic characteristics of human SGNs, advancing the process of guiding hESCs to states serving inner-ear cell-replacement therapies and possible next-generation hybrid auditory prostheses. © Stem Cells Translational Medicine 2017;6:923-936.
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Affiliation(s)
- Akihiro J. Matsuoka
- Department of Otolaryngology and Head and Neck SurgeryChicagoILUSA
- Department of Communication Sciences and DisordersChicagoILUSA
- Knowles Hearing CenterChicagoILUSA
| | | | - Chaoying Zhang
- Department of Otolaryngology and Head and Neck SurgeryChicagoILUSA
| | - Kazuaki Homma
- Department of Otolaryngology and Head and Neck SurgeryChicagoILUSA
- Knowles Hearing CenterChicagoILUSA
| | - Abdelhak Belmadani
- Department of Molecular Pharmacology and Biological ChemistryChicagoILUSA
| | | | - Duncan M. Chadly
- Department of Otolaryngology and Head and Neck SurgeryChicagoILUSA
| | - Shun Kobayashi
- Department of Otolaryngology and Head and Neck SurgeryChicagoILUSA
| | | | | | - Donna S. Whitlon
- Department of Otolaryngology and Head and Neck SurgeryChicagoILUSA
- Knowles Hearing CenterChicagoILUSA
| | - Ljuba Lyass
- Department of Biomedical EngineeringChicagoILUSA
| | | | - Samuel I. Stupp
- Department of MedicineChicagoILUSA
- Department of Biomedical EngineeringChicagoILUSA
- Simpson Querrey Institute for BioNanotechnologyChicagoILUSA
- Department of ChemistryNorthwestern University
- Department of Materials Science & EngineeringNorthwestern University
| | - John A. Kessler
- Department of NeurologyFeinberg School of Medicine, Northwestern UniversityChicagoILUSA
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19
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DeJonge RE, Liu XP, Deig CR, Heller S, Koehler KR, Hashino E. Modulation of Wnt Signaling Enhances Inner Ear Organoid Development in 3D Culture. PLoS One 2016; 11:e0162508. [PMID: 27607106 PMCID: PMC5015985 DOI: 10.1371/journal.pone.0162508] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 08/01/2016] [Indexed: 01/17/2023] Open
Abstract
Stem cell-derived inner ear sensory epithelia are a promising source of tissues for treating patients with hearing loss and dizziness. We recently demonstrated how to generate inner ear sensory epithelia, designated as inner ear organoids, from mouse embryonic stem cells (ESCs) in a self-organizing 3D culture. Here we improve the efficiency of this culture system by elucidating how Wnt signaling activity can drive the induction of otic tissue. We found that a carefully timed treatment with the potent Wnt agonist CHIR99021 promotes induction of otic vesicles—a process that was previously self-organized by unknown mechanisms. The resulting otic-like vesicles have a larger lumen size and contain a greater number of Pax8/Pax2-positive otic progenitor cells than organoids derived without the Wnt agonist. Additionally, these otic-like vesicles give rise to large inner ear organoids with hair cells whose morphological, biochemical and functional properties are indistinguishable from those of vestibular hair cells in the postnatal mouse inner ear. We conclude that Wnt signaling plays a similar role during inner ear organoid formation as it does during inner ear development in the embryo.
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Affiliation(s)
- Rachel E. DeJonge
- Department of Otolaryngology-Head and Neck Surgery, Indiana University School of Medicine, Indianapolis, IN, 46202, United States of America
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, 46202, United States of America
| | - Xiao-Ping Liu
- Department of Otolaryngology, F.M. Kirby Neurobiology Center Boston Children’s Hospital, and Harvard Medical School, Boston, MA, 02115, United States of America
| | - Christopher R. Deig
- Department of Otolaryngology-Head and Neck Surgery, Indiana University School of Medicine, Indianapolis, IN, 46202, United States of America
| | - Stefan Heller
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, Palo Alto, CA, 94305, United States of America
| | - Karl R. Koehler
- Department of Otolaryngology-Head and Neck Surgery, Indiana University School of Medicine, Indianapolis, IN, 46202, United States of America
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, 46202, United States of America
- * E-mail: (EH); (KRK)
| | - Eri Hashino
- Department of Otolaryngology-Head and Neck Surgery, Indiana University School of Medicine, Indianapolis, IN, 46202, United States of America
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, 46202, United States of America
- * E-mail: (EH); (KRK)
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20
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Wu J, Li W, Lin C, Chen Y, Cheng C, Sun S, Tang M, Chai R, Li H. Co-regulation of the Notch and Wnt signaling pathways promotes supporting cell proliferation and hair cell regeneration in mouse utricles. Sci Rep 2016; 6:29418. [PMID: 27435629 PMCID: PMC4951696 DOI: 10.1038/srep29418] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 06/16/2016] [Indexed: 02/07/2023] Open
Abstract
This work sought to determine the crosstalk between the Notch and Wnt signaling pathways in regulating supporting cell (SC) proliferation and hair cell (HC) regeneration in mouse utricles. We cultured postnatal day (P)3 and P60 mouse utricles, damaged the HCs with gentamicin, and treated the utricles with the γ-secretase inhibitor DAPT to inhibit the Notch pathway and with the Wnt agonist QS11 to active the Wnt pathway. We also used Sox2-CreER, Notch1-flox (exon 1), and Catnb-flox (exon 3) transgenic mice to knock out the Notch pathway and activate the Wnt pathway in Sox2+ SCs. Notch inhibition alone increased SC proliferation and HC number in both undamaged and damaged utricles. Wnt activation alone promoted SC proliferation, but the HC number was not significantly increased. Here we demonstrated the cumulative effects of Notch inhibition and Wnt activation in regulating SC proliferation and HC regeneration. Simultaneously inhibiting Notch and overexpressing Wnt led to significantly greater SC proliferation and greater numbers of HCs than manipulating either pathway alone. Similar results were observed in the transgenic mice. This study suggests that the combination of Notch inhibition and Wnt activation can significantly promote SC proliferation and increase the number of regenerated HCs in mouse utricle.
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Affiliation(s)
- Jingfang Wu
- Otorhinolaryngology Department of Affiliated Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200031, PR China.,Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, PR China
| | - Wenyan Li
- Otorhinolaryngology Department of Affiliated Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200031, PR China.,Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, PR China
| | - Chen Lin
- Otorhinolaryngology Department of Affiliated Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200031, PR China.,Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, PR China
| | - Yan Chen
- Otorhinolaryngology Department of Affiliated Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200031, PR China.,Central laboratory, Affiliated Eye and ENT Hospital of Fudan University, Shanghai, 200031, PR China.,Key Laboratory of Hearing Medicine of National Health and Family Planning Commission, Shanghai, 200031, PR China
| | - Cheng Cheng
- MOE Key Laboratory of Developmental Genes and Human Disease, State Key Laboratory of Bioelectronics, Institute of Life Sciences, Southeast University, Nanjing 210096, PR China.,Co-innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, PR China
| | - Shan Sun
- Otorhinolaryngology Department of Affiliated Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200031, PR China.,Central laboratory, Affiliated Eye and ENT Hospital of Fudan University, Shanghai, 200031, PR China.,Key Laboratory of Hearing Medicine of National Health and Family Planning Commission, Shanghai, 200031, PR China
| | - Mingliang Tang
- MOE Key Laboratory of Developmental Genes and Human Disease, State Key Laboratory of Bioelectronics, Institute of Life Sciences, Southeast University, Nanjing 210096, PR China.,Co-innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, PR China
| | - Renjie Chai
- MOE Key Laboratory of Developmental Genes and Human Disease, State Key Laboratory of Bioelectronics, Institute of Life Sciences, Southeast University, Nanjing 210096, PR China.,Co-innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, PR China
| | - Huawei Li
- Otorhinolaryngology Department of Affiliated Eye and ENT Hospital, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai, 200031, PR China.,Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, PR China.,Key Laboratory of Hearing Medicine of National Health and Family Planning Commission, Shanghai, 200031, PR China
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21
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Eroshkin FM, Nesterenko AM, Borodulin AV, Martynova NY, Ermakova GV, Gyoeva FK, Orlov EE, Belogurov AA, Lukyanov KA, Bayramov AV, Zaraisky AG. Noggin4 is a long-range inhibitor of Wnt8 signalling that regulates head development in Xenopus laevis. Sci Rep 2016; 6:23049. [PMID: 26973133 PMCID: PMC4789793 DOI: 10.1038/srep23049] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 02/25/2016] [Indexed: 12/05/2022] Open
Abstract
Noggin4 is a Noggin family secreted protein whose molecular and physiological functions remain unknown. In this study, we demonstrate that in contrast to other Noggins, Xenopus laevis Noggin4 cannot antagonise BMP signalling; instead, it specifically binds to Wnt8 and inhibits the Wnt/β -catenin pathway. Live imaging demonstrated that Noggin4 diffusivity in embryonic tissues significantly exceeded that of other Noggins. Using the Fluorescence Recovery After Photobleaching (FRAP) assay and mathematical modelling, we directly estimated the affinity of Noggin4 for Wnt8 in living embryos and determined that Noggin4 fine-tune the Wnt8 posterior-to-anterior gradient. Our results suggest a role for Noggin4 as a unique, freely diffusing, long-range inhibitor of canonical Wnt signalling, thus explaining its ability to promote head development.
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Affiliation(s)
- Fedor M Eroshkin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
| | - Alexey M Nesterenko
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia.,Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie gory, 1/40, 119991 Moscow, Russia
| | - Alexander V Borodulin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
| | - Natalia Yu Martynova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
| | - Galina V Ermakova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
| | - Fatima K Gyoeva
- Institute of Protein Research, Russian Academy of Sciences, Pushchino, 142290 Moscow Region, Russia
| | - Eugeny E Orlov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
| | - Alexey A Belogurov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
| | - Konstantin A Lukyanov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
| | - Andrey V Bayramov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
| | - Andrey G Zaraisky
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
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22
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Adameyko I, Fried K. The Nervous System Orchestrates and Integrates Craniofacial Development: A Review. Front Physiol 2016; 7:49. [PMID: 26924989 PMCID: PMC4759458 DOI: 10.3389/fphys.2016.00049] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 02/02/2016] [Indexed: 01/14/2023] Open
Abstract
Development of a head is a dazzlingly complex process: a number of distinct cellular sources including cranial ecto- and endoderm, mesoderm and neural crest contribute to facial and other structures. In the head, an extremely fine-tuned developmental coordination of CNS, peripheral neural components, sensory organs and a musculo-skeletal apparatus occurs, which provides protection and functional integration. The face can to a large extent be considered as an assembly of sensory systems encased and functionally fused with appendages represented by jaws. Here we review how the developing brain, neurogenic placodes and peripheral nerves influence the morphogenesis of surrounding tissues as a part of various general integrative processes in the head. The mechanisms of this impact, as we understand it now, span from the targeted release of the morphogens necessary for shaping to providing a niche for cellular sources required in later development. In this review we also discuss the most recent findings and ideas related to how peripheral nerves and nerve-associated cells contribute to craniofacial development, including teeth, during the post- neural crest period and potentially in regeneration.
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Affiliation(s)
- Igor Adameyko
- Department of Physiology and Pharmacology, Karolinska InstitutetStockholm, Sweden; Department of Molecular Neurosciences, Center of Brain Research, Medical University of ViennaVienna, Austria
| | - Kaj Fried
- Department of Neuroscience, Karolinska Institutet Stockholm, Sweden
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23
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Wright KD, Mahoney Rogers AA, Zhang J, Shim K. Cooperative and independent functions of FGF and Wnt signaling during early inner ear development. BMC DEVELOPMENTAL BIOLOGY 2015; 15:33. [PMID: 26443994 PMCID: PMC4594887 DOI: 10.1186/s12861-015-0083-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 09/18/2015] [Indexed: 12/28/2022]
Abstract
Background In multiple vertebrate organisms, including chick, Xenopus, and zebrafish, Fibroblast Growth Factor (FGF) and Wnt signaling cooperate during formation of the otic placode. However, in the mouse, although FGF signaling induces Wnt8a expression during induction of the otic placode, it is unclear whether these two signaling pathways functionally cooperate. Sprouty (Spry) genes encode intracellular antagonists of receptor tyrosine kinase signaling, including FGF signaling. We previously demonstrated that the Sprouty1 (Spry1) and Sprouty2 (Spry2) genes antagonize FGF signaling during induction of the otic placode. Here, we investigate cross talk between FGF/SPRY and Wnt signaling during otic placode induction and assess whether these two signaling pathways functionally cooperate during early inner ear development in the mouse. Methods Embryos were generated carrying combinations of a Spry1 null allele, Spry2 null allele, β-catenin null allele, or a Wnt reporter transgene. Otic phenotypes were assessed by in situ hybridization, semi-quantitative reverse transcriptase PCR, immunohistochemistry, and morphometric analysis of sectioned tissue. Results Comparison of Spry1, Spry2, and Wnt reporter expression in pre-otic and otic placode cells indicates that FGF signaling precedes and is active in more cells than Wnt signaling. We provide in vivo evidence that FGF signaling activates the Wnt signaling pathway upstream of TCF/Lef transcriptional activation. FGF regulation of Wnt signaling is functional, since early inner ear defects in Spry1 and Spry2 compound mutant embryos can be genetically rescued by reducing the activity of the Wnt signaling pathway. Interestingly, we find that although the entire otic placode increases in size in Spry1 and Spry2 compound mutant embryos, the size of the Wnt-reporter-positive domain does not increase to the same extent as the Wnt-reporter-negative domain. Conclusions This study provides genetic evidence that FGF and Wnt signaling cooperate during early inner ear development in the mouse. Furthermore, our data suggest that although specification of the otic placode may be globally regulated by FGF signaling, otic specification of cells in which both FGF and Wnt signaling are active may be more tightly regulated. Electronic supplementary material The online version of this article (doi:10.1186/s12861-015-0083-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Kevin D Wright
- Department of Pediatrics, Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, 53226, USA.
| | - Amanda A Mahoney Rogers
- Department of Pediatrics, Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, 53226, USA.
| | - Jian Zhang
- Department of Pediatrics, Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, 53226, USA.
| | - Katherine Shim
- Department of Pediatrics, Children's Research Institute, Medical College of Wisconsin, Milwaukee, WI, 53226, USA.
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24
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Abstract
Cranial sensory placodes derive from discrete patches of the head ectoderm and give rise to numerous sensory structures. During gastrulation, a specialized "neural border zone" forms around the neural plate in response to interactions between the neural and nonneural ectoderm and signals from adjacent mesodermal and/or endodermal tissues. This zone subsequently gives rise to two distinct precursor populations of the peripheral nervous system: the neural crest and the preplacodal ectoderm (PPE). The PPE is a common field from which all cranial sensory placodes arise (adenohypophyseal, olfactory, lens, trigeminal, epibranchial, otic). Members of the Six family of transcription factors are major regulators of PPE specification, in partnership with cofactor proteins such as Eya. Six gene activity also maintains tissue boundaries between the PPE, neural crest, and epidermis by repressing genes that specify the fates of those adjacent ectodermally derived domains. As the embryo acquires anterior-posterior identity, the PPE becomes transcriptionally regionalized, and it subsequently becomes subdivided into specific placodes with distinct developmental fates in response to signaling from adjacent tissues. Each placode is characterized by a unique transcriptional program that leads to the differentiation of highly specialized cells, such as neurosecretory cells, sensory receptor cells, chemosensory neurons, peripheral glia, and supporting cells. In this review, we summarize the transcriptional and signaling factors that regulate key steps of placode development, influence subsequent sensory neuron specification, and discuss what is known about mutations in some of the essential PPE genes that underlie human congenital syndromes.
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Affiliation(s)
- Sally A Moody
- Department of Anatomy and Regenerative Biology, The George Washington University, School of Medicine and Health Sciences, Washington, DC, USA; George Washington University Institute for Neuroscience, Washington, DC, USA.
| | - Anthony-Samuel LaMantia
- George Washington University Institute for Neuroscience, Washington, DC, USA; Department of Pharmacology and Physiology, The George Washington University, School of Medicine and Health Sciences, Washington, DC, USA
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25
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Yan B, Neilson KM, Ranganathan R, Maynard T, Streit A, Moody SA. Microarray identification of novel genes downstream of Six1, a critical factor in cranial placode, somite, and kidney development. Dev Dyn 2014; 244:181-210. [PMID: 25403746 DOI: 10.1002/dvdy.24229] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 11/03/2014] [Accepted: 11/12/2014] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND Six1 plays an important role in the development of several vertebrate organs, including cranial sensory placodes, somites, and kidney. Although Six1 mutations cause one form of branchio-otic syndrome (BOS), the responsible gene in many patients has not been identified; genes that act downstream of Six1 are potential BOS candidates. RESULTS We sought to identify novel genes expressed during placode, somite and kidney development by comparing gene expression between control and Six1-expressing ectodermal explants. The expression patterns of 19 of the significantly up-regulated and 11 of the significantly down-regulated genes were assayed from cleavage to larval stages. A total of 28/30 genes are expressed in the otocyst, a structure that is functionally disrupted in BOS, and 26/30 genes are expressed in the nephric mesoderm, a structure that is functionally disrupted in the related branchio-otic-renal (BOR) syndrome. We also identified the chick homologues of five genes and show that they have conserved expression patterns. CONCLUSIONS Of the 30 genes selected for expression analyses, all are expressed at many of the developmental times and appropriate tissues to be regulated by Six1. Many have the potential to play a role in the disruption of hearing and kidney function seen in BOS/BOR patients.
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Affiliation(s)
- Bo Yan
- Department of Anatomy and Regenerative Biology, The George Washington University, School of Medicine and Health Sciences, Washington, DC
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Maulding K, Padanad MS, Dong J, Riley BB. Mesodermal Fgf10b cooperates with other fibroblast growth factors during induction of otic and epibranchial placodes in zebrafish. Dev Dyn 2014; 243:1275-85. [PMID: 24677486 PMCID: PMC4313390 DOI: 10.1002/dvdy.24119] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Revised: 01/27/2014] [Accepted: 02/16/2014] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Vertebrate otic and epibranchial placodes develop in close proximity in response to localized fibroblast growth factor (Fgf) signaling. Although less is known about epibranchial induction, the process of otic induction in highly conserved, with important roles for Fgf3 and Fgf8 reported in all species examined. Fgf10 is also critical for otic induction in mouse, but the only zebrafish ortholog examined to date, fgf10a, is not expressed early enough to play such a role. A second zebrafish ortholog, fgf10b, has not been previously examined. RESULTS We find that zebrafish fgf10b is expressed at tailbud stage in paraxial cephalic mesoderm beneath prospective epibranchial tissue, lateral to the developing otic placode. Knockdown of fgf10b does not affect initial otic induction but impairs subsequent accumulation of otic cells. Formation of epibranchial placodes and ganglia are also moderately impaired. Combinatorial disruption of fgf10b and fgf3 exacerbates the deficiency of otic cells and eliminates epibranchial induction entirely. Disruption of fgf10b and fgf24 also strongly reduces, but does not eliminate, epibranchial induction. CONCLUSIONS fgf10b participates in a late phase of otic induction and, in combination with fgf3, is especially critical for epibranchial induction.
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Affiliation(s)
- Kirstin Maulding
- Biology Department, Texas A&M University, College Station, TX 77843-3258
| | - Mahesh S. Padanad
- Biology Department, Texas A&M University, College Station, TX 77843-3258
| | - Jennifer Dong
- Biology Department, Texas A&M University, College Station, TX 77843-3258
| | - Bruce B. Riley
- Biology Department, Texas A&M University, College Station, TX 77843-3258
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Hong CS, Devotta A, Lee YH, Park BY, Saint-Jeannet JP. Transcription factor AP2 epsilon (Tfap2e) regulates neural crest specification in Xenopus. Dev Neurobiol 2014; 74:894-906. [PMID: 24616412 DOI: 10.1002/dneu.22173] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 01/24/2014] [Accepted: 02/13/2014] [Indexed: 02/01/2023]
Abstract
Transcription factors Pax3 and Zic1 are two important regulators of cell fate decision at the neural plate border, where they act synergistically to promote neural crest (NC) formation. To understand the role of these factors in NC development, we performed a microarray analysis to identify downstream targets of Pax3 and Zic1 in Xenopus embryos. Among the genes identified was a member of transcription factor activator protein 2 (Tfap2) family, Tfap2 epsilon (Tfap2e). Tfap2e is first expressed at early neurula stage in NC progenitors and Rohon-Beard sensory neurons, and persists in a subset of migrating cranial NC cells as they populate the pharyngeal arches. This is in contrast to other species in which Tfap2e is not detected in the early NC lineage. Tfap2e morpholino-mediated knockdown results in a loss of NC progenitors and an expansion of the neural plate. Tfap2e is also sufficient to activate NC-specific genes in animal cap explants, and gain-of-function experiments in the whole embryo indicate that Tfap2e can promote NC formation. We propose that Tfap2e is a novel player in the gene regulatory network controlling NC specification in Xenopus downstream of Pax3 and Zic1.
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Affiliation(s)
- Chang-Soo Hong
- Department of Biological Sciences, College of Natural Sciences, Daegu University, Gyeongsan, Republic of Korea; Department of Basic Science and Craniofacial Biology, College of Dentistry, New York University, New York, New York
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Saint-Jeannet JP, Moody SA. Establishing the pre-placodal region and breaking it into placodes with distinct identities. Dev Biol 2014; 389:13-27. [PMID: 24576539 DOI: 10.1016/j.ydbio.2014.02.011] [Citation(s) in RCA: 115] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Revised: 02/13/2014] [Accepted: 02/14/2014] [Indexed: 11/17/2022]
Abstract
Specialized sensory organs in the vertebrate head originate from thickenings in the embryonic ectoderm called cranial sensory placodes. These placodes, as well as the neural crest, arise from a zone of ectoderm that borders the neural plate. This zone separates into a precursor field for the neural crest that lies adjacent to the neural plate, and a precursor field for the placodes, called the pre-placodal region (PPR), that lies lateral to the neural crest. The neural crest domain and the PPR are established in response to signaling events mediated by BMPs, FGFs and Wnts, which differentially activate transcription factors in these territories. In the PPR, members of the Six and Eya families, act in part to repress neural crest specific transcription factors, thus solidifying a placode developmental program. Subsequently, in response to environmental cues the PPR is further subdivided into placodal territories with distinct characteristics, each expressing a specific repertoire of transcription factors that provide the necessary information for their progression to mature sensory organs. In this review we summarize recent advances in the characterization of the signaling molecules and transcriptional effectors that regulate PPR specification and its subdivision into placodal domains with distinct identities.
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Affiliation(s)
- Jean-Pierre Saint-Jeannet
- Department of Basic Science and Craniofacial Biology, New York University, College of Dentistry, 345 East 24th Street, New York City, NY 10010, USA.
| | - Sally A Moody
- Department of Anatomy and Regenerative Biology, The George Washington University, School of Medicine and Health Sciences, 2300 I (eye) Street, NW, Washington, DC 20037, USA.
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29
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Bae CJ, Park BY, Lee YH, Tobias JW, Hong CS, Saint-Jeannet JP. Identification of Pax3 and Zic1 targets in the developing neural crest. Dev Biol 2013; 386:473-83. [PMID: 24360908 DOI: 10.1016/j.ydbio.2013.12.011] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Revised: 10/07/2013] [Accepted: 12/10/2013] [Indexed: 11/28/2022]
Abstract
The neural crest (NC) is a multipotent population of migratory cells unique to the vertebrate embryo, contributing to the development of multiple organ systems. Transcription factors pax3 and zic1 are among the earliest genes activated in NC progenitors, and they are both necessary and sufficient to promote NC fate. In order to further characterize the function of these transcription factors during NC development we have used hormone inducible fusion proteins in a Xenopus animal cap assay, and DNA microarray to identify downstream targets of Pax3 and Zic1. Here we present the results of this screen and the initial validation of these targets using quantitative RT-PCR, in situ hybridization and morpholinos-mediated knockdown. Among the targets identified we found several well-characterized NC-specific genes, including snail2, foxd3, gbx2, twist, sox8 and sox9, which validate our approach. We also obtained several factors with no known function in Xenopus NC, which represent novel regulators of NC fate. The comprehensive characterization of Pax3 and Zic1 targets function in the NC gene regulatory network, are essential to understanding the mechanisms regulating the emergence of this important cell population.
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Affiliation(s)
- Chang-Joon Bae
- Department of Basic Science & Craniofacial Biology, College of Dentistry, New York University, New York, USA
| | - Byung-Yong Park
- Department of Anatomy, College of Veterinary Medicine, Chonbuk National University, Jeonju, Republic of Korea
| | - Young-Hoon Lee
- Department of Oral Anatomy, School of Dentistry & Institute of Oral Biosciences, Chonbuk National University, Jeonju, Republic of Korea
| | - John W Tobias
- Bioinformatics Group, Molecular Profiling Facility, University of Pennsylvania, Philadelphia, PA, USA
| | - Chang-Soo Hong
- Department of Basic Science & Craniofacial Biology, College of Dentistry, New York University, New York, USA; Department of Biological Sciences, College of Natural Sciences, Daegu University, Gyeongsan, Republic of Korea.
| | - Jean-Pierre Saint-Jeannet
- Department of Basic Science & Craniofacial Biology, College of Dentistry, New York University, New York, USA; Department of Animal Biology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA, USA.
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30
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Hulstrand AM, Houston DW. Regulation of neurogenesis by Fgf8a requires Cdc42 signaling and a novel Cdc42 effector protein. Dev Biol 2013; 382:385-99. [PMID: 23994638 DOI: 10.1016/j.ydbio.2013.08.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Revised: 08/11/2013] [Accepted: 08/21/2013] [Indexed: 11/16/2022]
Abstract
Fibroblast growth factor (FGF) signaling is required for numerous aspects of neural development, including neural induction, CNS patterning and neurogenesis. The ability of FGFs to activate Ras/MAPK signaling is thought to be critical for these functions. However, it is unlikely that MAPK signaling can fully explain the diversity of responses to FGFs. We have characterized a Cdc42-dependent signaling pathway operating downstream of the Fgf8a splice isoform. We show that a Cdc42 effector 4-like protein (Cdc42ep4-l or Cep4l) has robust neuronal-inducing activity in Xenopus embryos. Furthermore, we find that Cep4l and Cdc42 itself are necessary and sufficient for sensory neurogenesis in vivo. Furthermore, both proteins are involved in Fgf8a-induced neuronal induction, and Cdc42/Cep4l association is promoted specifically by the Fgf8a isoform of Fgf8, but not by Fgf8b, which lacks neuronal inducing activity. Overall, these data suggest a novel role for Cdc42 in an Fgf8a-specific signaling pathway essential for vertebrate neuronal development.
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Affiliation(s)
- Alissa M Hulstrand
- Department of Biology and Interdisciplinary Graduate Program in Genetics, University of Iowa, Iowa City, IA 52242, USA
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31
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Burns JC, Corwin JT. A historical to present-day account of efforts to answer the question: "what puts the brakes on mammalian hair cell regeneration?". Hear Res 2013; 297:52-67. [PMID: 23333259 PMCID: PMC3594491 DOI: 10.1016/j.heares.2013.01.005] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2012] [Revised: 12/20/2012] [Accepted: 01/07/2013] [Indexed: 12/17/2022]
Abstract
Hearing and balance deficits often affect humans and other mammals permanently, because their ears stop producing hair cells within a few days after birth. But production occurs throughout life in the ears of sharks, bony fish, amphibians, reptiles, and birds allowing them to replace lost hair cells and quickly recover after temporarily experiencing the kinds of sensory deficits that are irreversible for mammals. Since the mid 1970s, researchers have been asking what puts the brakes on hair cell regeneration in mammals. Here we evaluate the headway that has been made and assess current evidence for alternative mechanistic hypotheses that have been proposed to account for the limits to hair cell regeneration in mammals.
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Affiliation(s)
- Joseph C Burns
- Department of Neuroscience, University of Virginia, School of Medicine, Charlottesville, VA 22908, USA.
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Yang L, O'Neill P, Martin K, Maass JC, Vassilev V, Ladher R, Groves AK. Analysis of FGF-dependent and FGF-independent pathways in otic placode induction. PLoS One 2013; 8:e55011. [PMID: 23355906 PMCID: PMC3552847 DOI: 10.1371/journal.pone.0055011] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 12/10/2012] [Indexed: 12/27/2022] Open
Abstract
The inner ear develops from a patch of thickened cranial ectoderm adjacent to the hindbrain called the otic placode. Studies in a number of vertebrate species suggest that the initial steps in induction of the otic placode are regulated by members of the Fibroblast Growth Factor (FGF) family, and that inhibition of FGF signaling can prevent otic placode formation. To better understand the genetic pathways activated by FGF signaling during otic placode induction, we performed microarray experiments to estimate the proportion of chicken otic placode genes that can be up-regulated by the FGF pathway in a simple culture model of otic placode induction. Surprisingly, we find that FGF is only sufficient to induce about 15% of chick otic placode-specific genes in our experimental system. However, pharmacological blockade of the FGF pathway in cultured chick embryos showed that although FGF signaling was not sufficient to induce the majority of otic placode-specific genes, it was still necessary for their expression in vivo. These inhibitor experiments further suggest that the early steps in otic placode induction regulated by FGF signaling occur through the MAP kinase pathway. Although our work suggests that FGF signaling is necessary for otic placode induction, it demonstrates that other unidentified signaling pathways are required to co-operate with FGF signaling to induce the full otic placode program.
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Affiliation(s)
- Lu Yang
- Departments of Neuroscience and Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
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33
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Gunewardene N, Dottori M, Nayagam BA. The convergence of cochlear implantation with induced pluripotent stem cell therapy. Stem Cell Rev Rep 2012; 8:741-54. [PMID: 21956409 DOI: 10.1007/s12015-011-9320-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
According to 2010 estimates from The National Institute on Deafness and other Communication Disorders, approximately 17% (36 million) American adults have reported some degree of hearing loss. Currently, the only clinical treatment available for those with severe-to-profound hearing loss is a cochlear implant, which is designed to electrically stimulate the auditory nerve in the absence of hair cells. Whilst the cochlear implant has been revolutionary in terms of providing hearing to the severe-to-profoundly deaf, there are variations in cochlear implant performance which may be related to the degree of degeneration of auditory neurons following hearing loss. Hence, numerous experimental studies have focused on enhancing the efficacy of cochlear implants by using neurotrophins to preserve the auditory neurons, and more recently, attempting to replace these dying cells with new neurons derived from stem cells. As a result, several groups are now investigating the potential for both embryonic and adult stem cells to replace the degenerating sensory elements in the deaf cochlea. Recent advances in our knowledge of stem cells and the development of induced pluripotency by Takahashi and Yamanaka in 2006, have opened a new realm of science focused on the use of induced pluripotent stem (iPS) cells for therapeutic purposes. This review will provide a broad overview of the potential benefits and challenges of using iPS cells in combination with a cochlear implant for the treatment of hearing loss, including differentiation of iPS cells into an auditory neural lineage and clinically relevant transplantation approaches.
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Affiliation(s)
- Niliksha Gunewardene
- Department of Otolaryngology, University of Melbourne, Melbourne, Victoria, Australia
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34
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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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35
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Vendrell V, Vázquez-Echeverría C, López-Hernández I, Alonso BD, Martinez S, Pujades C, Schimmang T. Roles of Wnt8a during formation and patterning of the mouse inner ear. Mech Dev 2012; 130:160-8. [PMID: 23041177 DOI: 10.1016/j.mod.2012.09.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Revised: 09/25/2012] [Accepted: 09/26/2012] [Indexed: 12/22/2022]
Abstract
Fgf and Wnt signalling have been shown to be required for formation of the otic placode in vertebrates. Whereas several Fgfs including Fgf3, Fgf8 and Fgf10 have been shown to participate during early placode induction, Wnt signalling is required for specification and maintenance of the otic placode, and dorsal patterning of the otic vesicle. However, the requirement for specific members of the Wnt gene family for otic placode and vesicle formation and their potential interaction with Fgf signalling has been poorly defined. Due to its spatiotemporal expression during placode formation in the hindbrain Wnt8a has been postulated as a potential candidate for its specification. Here we have examined the role of Wnt8a during formation of the otic placode and vesicle in mouse embryos. Wnt8a expression depends on the presence of Fgf3 indicating a serial regulation between Fgf and Wnt signalling during otic placode induction and specification. Wnt8a by itself however is neither essential for placode specification nor redundantly required together with Fgfs for otic placode and vesicle formation. Interestingly however, Wnt8a and Fgf3 are redundantly required for expression of Fgf15 in the hindbrain indicating additional reciprocal interactions between Fgf and Wnt signalling. Further reduction of Wnt signalling by the inactivation of Wnt1 in a Wnt8a mutant background revealed a redundant requirement for both genes during morphogenesis of the dorsal portion of the otic vesicle.
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Affiliation(s)
- Victor Vendrell
- Instituto de Biología y Genética Molecular, Universidad de Valladolid y Consejo Superior de Investigaciones Científicas, C/Sanz y Forés 3, E-47003 Valladolid, Spain.
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36
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McCarroll MN, Lewis ZR, Culbertson MD, Martin BL, Kimelman D, Nechiporuk AV. Graded levels of Pax2a and Pax8 regulate cell differentiation during sensory placode formation. Development 2012; 139:2740-50. [PMID: 22745314 PMCID: PMC3392703 DOI: 10.1242/dev.076075] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/10/2012] [Indexed: 01/11/2023]
Abstract
Pax gene haploinsufficiency causes a variety of congenital defects. Renal-coloboma syndrome, resulting from mutations in Pax2, is characterized by kidney hypoplasia, optic nerve malformation, and hearing loss. Although this underscores the importance of Pax gene dosage in normal development, how differential levels of these transcriptional regulators affect cell differentiation and tissue morphogenesis is still poorly understood. We show that differential levels of zebrafish Pax2a and Pax8 modulate commitment and behavior in cells that eventually contribute to the otic vesicle and epibranchial placodes. Initially, a subset of epibranchial placode precursors lie lateral to otic precursors within a single Pax2a/8-positive domain; these cells subsequently move to segregate into distinct placodes. Using lineage-tracing and ablation analyses, we show that cells in the Pax2a/8+ domain become biased towards certain fates at the beginning of somitogenesis. Experiments involving either Pax2a overexpression or partial, combinatorial Pax2a and Pax8 loss of function reveal that high levels of Pax favor otic differentiation whereas low levels increase cell numbers in epibranchial ganglia. In addition, the Fgf and Wnt signaling pathways control Pax2a expression: Fgf is necessary to induce Pax2a, whereas Wnt instructs the high levels of Pax2a that favor otic differentiation. Our studies reveal the importance of Pax levels during sensory placode formation and provide a mechanism by which these levels are controlled.
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Affiliation(s)
- Matthew N. McCarroll
- Department of Cell and Developmental Biology, Oregon Health & Science University, Portland, Oregon, 97239, USA
| | - Zachary R. Lewis
- Department of Cell and Developmental Biology, Oregon Health & Science University, Portland, Oregon, 97239, USA
| | - Maya Deza Culbertson
- Department of Cell and Developmental Biology, Oregon Health & Science University, Portland, Oregon, 97239, USA
| | | | - David Kimelman
- Department of Biochemistry, Box 357350, Seattle, Washington 98195, USA
| | - Alex V. Nechiporuk
- Department of Cell and Developmental Biology, Oregon Health & Science University, Portland, Oregon, 97239, USA
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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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38
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Horn ER, El-Yamany NA, Gradl D. The vestibuloocular reflex of tadpoles (Xenopus laevis) after knock-down of the isthmus related transcription factor XTcf-4. J Exp Biol 2012; 216:733-41. [DOI: 10.1242/jeb.079319] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Summary
Development of the amphibian vestibular organ is regulated by molecular and neuronal mechanisms and by environmental input. The molecular component includes inductive signals derived from neural tissue of the hindbrain and from the surrounding mesoderm. The integrity of hindbrain patterning, on the other hand, depends on instructive signals from the isthmus organizer of the midbrain including the transcription factor XTcf-4. If the development of the vestibular system depends on the integrity of the isthmus as organizing centre, suppression of isthmus maintenance should modify vestibular morphology and function. We tested this hypothesis by down-regulation of the transcription factor XTcf-4. 10 pMol XTcf-4-specific antisense morpholino oligonucleotide were injected in one blastomere of 2-cell stage embryos of Xenopus laevis. For reconstitution experiments, 500 pg mRNA of the repressing XTcf-4A isoform or the activating XTcf-4C isoform were co-injected. Over-expression experiments were included using the same isoforms. Otoconia formation and vestibular controlled behaviour such as the roll-induced vestibuloocular reflex (rVOR) and swimming were recorded two weeks later. In 50% of tadpoles, down-regulation of XTcf-4 induced (1) a depression of otoconia formation accompanied by a reduction of the rVOR, (2) abnormal tail development, and (3) loop swimming behaviour. (4) All effects were rescued by co-injection of XTcf-4C but not or only partially by XTcf-4A. (5) Over-expression of XTcf-4A caused similar morphological and rVOR modifications as XTcf-4 depletion while over-expression of XTcf-4C had no effect. Because XTcf-4C has been described as essential factor for isthmus development, we postulate that the isthmus is strongly involved in vestibular development.
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Affiliation(s)
- Eberhard R. Horn
- Zoological Institute, Cell and Developmental Biology, Karlsruhe Institute of Technology, Germany
| | | | - Dietmar Gradl
- Zoological Institute, Cell and Developmental Biology, Karlsruhe Institute of Technology, Germany
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Park BY, Hong CS, Weaver JR, Rosocha EM, Saint-Jeannet JP. Xaml1/Runx1 is required for the specification of Rohon-Beard sensory neurons in Xenopus. Dev Biol 2011; 362:65-75. [PMID: 22173066 DOI: 10.1016/j.ydbio.2011.11.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Revised: 11/14/2011] [Accepted: 11/21/2011] [Indexed: 11/27/2022]
Abstract
Lower vertebrates develop a unique set of primary sensory neurons located in the dorsal spinal cord. These cells, known as Rohon-Beard (RB) sensory neurons, innervate the skin and mediate the response to touch during larval stages. Here we report the expression and function of the transcription factor Xaml1/Runx1 during RB sensory neurons formation. In Xenopus embryos Runx1 is specifically expressed in RB progenitors at the end of gastrulation. Runx1 expression is positively regulated by Fgf and canonical Wnt signaling and negatively regulated by Notch signaling, the same set of factors that control the development of other neural plate border cell types, i.e. the neural crest and cranial placodes. Embryos lacking Runx1 function fail to differentiate RB sensory neurons and lose the mechanosensory response to touch. At early stages Runx1 knockdown results in a RB progenitor-specific loss of expression of Pak3, a p21-activated kinase that promotes cell cycle withdrawal, and of N-tub, a neuronal-specific tubulin. Interestingly, the pro-neural gene Ngnr1, an upstream regulator of Pak3 and N-tub, is either unaffected or expanded in these embryos, suggesting the existence of two distinct regulatory pathways controlling sensory neuron formation in Xenopus. Consistent with this possibility Ngnr1 is not sufficient to activate Runx1 expression in the ectoderm. We propose that Runx1 function is critically required for the generation of RB sensory neurons, an activity reminiscent of that of Runx1 in the development of the mammalian dorsal root ganglion nociceptive sensory neurons.
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Affiliation(s)
- Byung-Yong Park
- Department of Anatomy, College of Veterinary Medicine, Chonbuk National University, Jeonju, Republic of Korea
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Takebayashi-Suzuki K, Kitayama A, Terasaka-Iioka C, Ueno N, Suzuki A. The forkhead transcription factor FoxB1 regulates the dorsal-ventral and anterior-posterior patterning of the ectoderm during early Xenopus embryogenesis. Dev Biol 2011; 360:11-29. [PMID: 21958745 DOI: 10.1016/j.ydbio.2011.09.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Revised: 08/04/2011] [Accepted: 09/05/2011] [Indexed: 12/18/2022]
Abstract
The formation of the dorsal-ventral (DV) and anterior-posterior (AP) axes, fundamental to the body plan of animals, is regulated by several groups of polypeptide growth factors including the TGF-β, FGF, and Wnt families. In order to ensure the establishment of the body plan, the processes of DV and AP axis formation must be linked and coordinately regulated. However, the molecular mechanisms responsible for these interactions remain unclear. Here, we demonstrate that the forkhead box transcription factor FoxB1, which is upregulated by the neuralizing factor Oct-25, plays an important role in the formation of the DV and AP axes. Overexpression of FoxB1 promoted neural induction and inhibited BMP-dependent epidermal differentiation in ectodermal explants, thereby regulating the DV patterning of the ectoderm. In addition, FoxB1 was also found to promote the formation of posterior neural tissue in both ectodermal explants and whole embryos, suggesting its involvement in embryonic AP patterning. Using knockdown analysis, we found that FoxB1 is required for the formation of posterior neural tissues, acting in concert with the Wnt and FGF pathways. Consistent with this, FoxB1 suppressed the formation of anterior structures via a process requiring the function of XWnt-8 and eFGF. Interestingly, while downregulation of FoxB1 had little effect on neural induction, we found that it functionally interacted with its upstream factor Oct-25 and plays a supportive role in the induction and/or maintenance of neural tissue. Our results suggest that FoxB1 is part of a mechanism that fine-tunes, and leads to the coordinated formation of, the DV and AP axes during early development.
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Affiliation(s)
- Kimiko Takebayashi-Suzuki
- Institute for Amphibian Biology, Hiroshima University Graduate School of Science, Kagamiyama 1-3-1, Higashi-Hiroshima, Japan
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Jung B, Köhler A, Schambony A, Wedlich D. PAPC and the Wnt5a/Ror2 pathway control the invagination of the otic placode in Xenopus. BMC DEVELOPMENTAL BIOLOGY 2011; 11:36. [PMID: 21663658 PMCID: PMC3127988 DOI: 10.1186/1471-213x-11-36] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Accepted: 06/10/2011] [Indexed: 01/16/2023]
Abstract
BACKGROUND Paraxial protocadherin (PAPC) plays a crucial role in morphogenetic movements during gastrulation and somitogenesis in mouse, zebrafish and Xenopus. PAPC influences cell-cell adhesion mediated by C-Cadherin. A putative direct adhesion activity of PAPC is discussed. PAPC also promotes cell elongation, tissue separation and coordinates cell mass movements. In these processes the signaling function of PAPC in activating RhoA/JNK and supporting Wnt-11/PCP by binding to frizzled 7 (fz7) is important. RESULTS Here we demonstrate by loss of function experiments in Xenopus embryos that PAPC regulates another type of morphogenetic movement, the invagination of the ear placode. Knockdown of PAPC by antisense morpholinos results in deformation of the otic vesicle without altering otocyst marker expression. Depletion of PAPC could be rescued by full-length PAPC, constitutive active RhoA and by the closely related PCNS but not by classical cadherins. Also the cytoplasmic deletion mutant M-PAPC, which influences cell adhesion, does not rescue the PAPC knockdown. Interestingly, depletion of Wnt5a or Ror2 which are also expressed in the otocyst phenocopies the PAPC morphant phenotype. CONCLUSIONS PAPC signaling via RhoA and Wnt5a/Ror2 activity are required to keep cells aligned in apical-basal orientation during invagination of the ear placode. Since neither the cytoplasmic deletion mutant M-PAPC nor a classical cadherin is able to rescue loss of PAPC we suggest that the signaling function of the protocadherin rather than its role as modulator of cell-cell adhesion is required during invagination of the ear placode.
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Affiliation(s)
- Barbara Jung
- Karlsruhe Institute of Technology, Department of Cell and Developmental Biology, Karlsruhe, Germany
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Sprouty1 and Sprouty2 limit both the size of the otic placode and hindbrain Wnt8a by antagonizing FGF signaling. Dev Biol 2011; 353:94-104. [PMID: 21362415 DOI: 10.1016/j.ydbio.2011.02.022] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2010] [Revised: 02/18/2011] [Accepted: 02/20/2011] [Indexed: 11/21/2022]
Abstract
Multiple signaling molecules, including Fibroblast Growth Factor (FGF) and Wnt, induce two patches of ectoderm on either side of the hindbrain to form the progenitor cell population for the inner ear, or otic placode. Here we report that in Spry1, Spry2 compound mutant embryos (Spry1⁻/⁻; Spry2⁻/⁻ embryos), the otic placode is increased in size. We demonstrate that the otic placode is larger due to the recruitment of cells, normally destined to become cranial epidermis, into the otic domain. The enlargement of the otic placode observed in Spry1⁻/⁻; Spry2⁻/⁻ embryos is preceded by an expansion of a Wnt8a expression domain in the adjacent hindbrain. We demonstrate that both the enlargement of the otic placode and the expansion of the Wnt8a expression domain can be rescued in Spry1⁻/⁻; Spry2⁻/⁻ embryos by reducing the gene dosage of Fgf10. Our results define a FGF-responsive window during which cells can be continually recruited into the otic domain and uncover SPRY regulation of the size of a putative Wnt inductive center.
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Padanad MS, Riley BB. Pax2/8 proteins coordinate sequential induction of otic and epibranchial placodes through differential regulation of foxi1, sox3 and fgf24. Dev Biol 2011; 351:90-8. [PMID: 21215261 DOI: 10.1016/j.ydbio.2010.12.036] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2010] [Revised: 12/15/2010] [Accepted: 12/17/2010] [Indexed: 11/24/2022]
Abstract
Vertebrate cranial placodes contribute vitally to development of sensory structures of the head. Amongst posterior placodes, the otic placode forms the inner ear whereas nearby epibranchial placodes produce sensory ganglia within branchial clefts. Though diverse in fate, these placodes show striking similarities in their early regulation. In zebrafish, both are initiated by localized Fgf signaling plus the ubiquitous competence factor Foxi1, and both express pax8 and sox3 in response. It has been suggested that Fgf initially induces a common otic/epibranchial field, which later subdivides in response to other signals. However, we find that otic and epibranchial placodes form at different times and by distinct mechanisms. Initially, Fgf from surrounding tissues induces otic expression of pax8 and sox3, which cooperate synergistically to establish otic fate. Subsequently, pax8 works with related genes pax2a/pax2b to downregulate otic expression of foxi1, a necessary step for further otic development. Additionally, pax2/8 activate otic expression of fgf24, which induces epibranchial expression of sox3. Knockdown of fgf24 or sox3 causes severe epibranchial deficiencies but has little effect on otic development. These findings clarify the roles of pax8 and sox3 and support a model whereby the otic placode forms first and induces epibranchial placodes through an Fgf-relay.
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Affiliation(s)
- Mahesh S Padanad
- Biology Department, Texas A&M University, College Station, TX 77843-3258, USA
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Ladher RK, O'Neill P, Begbie J. From shared lineage to distinct functions: the development of the inner ear and epibranchial placodes. Development 2010; 137:1777-85. [PMID: 20460364 DOI: 10.1242/dev.040055] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The inner ear and the epibranchial ganglia constitute much of the sensory system in the caudal vertebrate head. The inner ear consists of mechanosensory hair cells, their neurons, and structures necessary for sound and balance sensation. The epibranchial ganglia are knots of neurons that innervate and relay sensory signals from several visceral organs and the taste buds. Their development was once thought to be independent, in line with their independent functions. However, recent studies indicate that both systems arise from a morphologically distinct common precursor domain: the posterior placodal area. This review summarises recent studies into the induction, morphogenesis and innervation of these systems and discusses lineage restriction and cell specification in the context of their common origin.
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Affiliation(s)
- Raj K Ladher
- RIKEN Center for Developmental Biology, Chuoku, Kobe 650-0047, Japan.
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Urness LD, Paxton CN, Wang X, Schoenwolf GC, Mansour SL. FGF signaling regulates otic placode induction and refinement by controlling both ectodermal target genes and hindbrain Wnt8a. Dev Biol 2010; 340:595-604. [PMID: 20171206 PMCID: PMC2854211 DOI: 10.1016/j.ydbio.2010.02.016] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2010] [Revised: 02/10/2010] [Accepted: 02/10/2010] [Indexed: 12/25/2022]
Abstract
The inner ear epithelium, with its complex array of sensory, non-sensory, and neuronal cell types necessary for hearing and balance, is derived from a thickened patch of head ectoderm called the otic placode. Mouse embryos lacking both Fgf3 and Fgf10 fail to initiate inner ear development because appropriate patterns of gene expression fail to be specified within the pre-otic field. To understand the transcriptional "blueprint" initiating inner ear development, we used microarray analysis to identify prospective placode genes that were differentially expressed in control and Fgf3(-)(/)(-);Fgf10(-)(/)(-) embryos. Several genes in the down-regulated class, including Hmx3, Hmx2, Foxg1, Sox9, Has2, and Slc26a9 were validated by in situ hybridization. We also assayed candidate target genes suggested by other studies of otic induction. Two placode markers, Fgf4 and Foxi3, were down-regulated in Fgf3(-)(/)(-);Fgf10(-)(/)(-) embryos, whereas Foxi2, a cranial epidermis marker, was expanded in double mutants, similar to its behavior when WNT responses are blocked in the otic placode. Assays of hindbrain Wnt genes revealed that only Wnt8a was reduced or absent in FGF-deficient embryos, and that even some Fgf3(-)(/)(-);Fgf10(-)(/+) and Fgf3(-)(/)(-) embryos failed to express Wnt8a, suggesting a key role for Fgf3, and a secondary role for Fgf10, in Wnt8a expression. Chick explant assays showed that FGF3 or FGF4, but not FGF10, were sufficient to induce Wnt8a. Collectively, our results suggest that Wnt8a provides the link between FGF-induced formation of the pre-otic field and restriction of the otic placode to ectoderm adjacent to the hindbrain.
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Affiliation(s)
- Lisa D. Urness
- Department of Human Genetics, University of Utah, 15 N 2030 E, RM 2100, Salt Lake City, UT 84112-5330, USA
| | - Christian N. Paxton
- Department of Neurobiology and Anatomy, University of Utah, 30 N 1900 E, RM 2R066 SOM, Salt Lake City, UT 84132-3401, USA
| | - Xiaofen Wang
- Department of Human Genetics, University of Utah, 15 N 2030 E, RM 2100, Salt Lake City, UT 84112-5330, USA
| | - Gary C. Schoenwolf
- Department of Neurobiology and Anatomy, University of Utah, 30 N 1900 E, RM 2R066 SOM, Salt Lake City, UT 84132-3401, USA
| | - Suzanne L. Mansour
- Department of Human Genetics, University of Utah, 15 N 2030 E, RM 2100, Salt Lake City, UT 84112-5330, USA
- Department of Neurobiology and Anatomy, University of Utah, 30 N 1900 E, RM 2R066 SOM, Salt Lake City, UT 84132-3401, USA
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Sienknecht UJ, Fekete DM. Mapping of Wnt, frizzled, and Wnt inhibitor gene expression domains in the avian otic primordium. J Comp Neurol 2010; 517:751-64. [PMID: 19842206 DOI: 10.1002/cne.22169] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Wnt signaling activates at least three different pathways involved in development and disease. Interactions of secreted ligands and inhibitors with cell-surface receptors result in the activation or regulation of particular downstream intracellular cascades. During the developmental stages of otic vesicle closure and beginning morphogenesis, the forming inner ear transcribes a plethora of Wnt-related genes. We report expression of 23 genes out of 25 tested in situ hybridization probes on tissue serial sections. Sensory primordia and Frizzled gene expression share domains, with Fzd1 being a continuous marker. Prospective nonsensory domains express Wnts, whose transcripts mainly flank prosensory regions. Finally, Wnt inhibitor domains are superimposed over both prosensory and nonsensory otic regions. Three Wnt antagonists, Dkk1, SFRP2, and Frzb are prominent. Their gene expression patterns partly overlap and change over time, which adds to the diversity of molecular microenvironments. Strikingly, prosensory domains express Wnts transiently. This includes: 1) the prosensory otic region of high proliferation, neuroblast delamination, and programmed cell death at stage 20/21 (Wnt3, -5b, -7b, -8b, -9a, and -11); and 2) sensory primordia at stage 25 (Wnt7a and Wnt9a). In summary, robust Wnt-related gene expression shows both spatial and temporal tuning during inner ear development as the otic vesicle initiates morphogenesis and prosensory cell fate determination.
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Affiliation(s)
- Ulrike J Sienknecht
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, USA
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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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Paxton CN, Bleyl SB, Chapman SC, Schoenwolf GC. Identification of differentially expressed genes in early inner ear development. Gene Expr Patterns 2009; 10:31-43. [PMID: 19913109 DOI: 10.1016/j.gep.2009.11.002] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2009] [Revised: 10/30/2009] [Accepted: 11/05/2009] [Indexed: 01/06/2023]
Abstract
To understand the etiology of congenital hearing loss, a comprehensive understanding of the molecular genetic mechanisms underlying normal ear development is required. We are identifying genes involved in otogenesis, with the longer term goal of studying their mechanisms of action, leading to inner ear induction and patterning. Using Agilent microarrays, we compared the differential expression of a test domain (which consisted of the pre-otic placodal ectoderm with the adjacent hindbrain ectoderm and the underlying mesendodermal tissues) with a rostral control domain (which included tissue that is competent, but not specified, to express inner ear markers in explant assays). We identified 1261 transcripts differentially expressed between the two domains at a 2-fold or greater change: 463 were upregulated and 798 were downregulated in the test domain. We validated the differential expression of several signaling molecules and transcription factors identified in this array using in situ hybridization. Furthermore, the expression patterns of the validated group of genes from the test domain were explored in detail to determine how the timing of their expression relates to specific events of otic induction and development. In conclusion, we identified a number of novel candidate genes for otic placode induction.
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Affiliation(s)
- Christian N Paxton
- University of Utah, Dept. of Neurobiology and Anatomy, Salt Lake City, UT 84132-3401, USA
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49
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Barembaum M, Bronner-Fraser M. Pax2 and Pea3 synergize to activate a novel regulatory enhancer for spalt4 in the developing ear. Dev Biol 2009; 340:222-31. [PMID: 19913005 DOI: 10.1016/j.ydbio.2009.11.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Revised: 10/30/2009] [Accepted: 11/02/2009] [Indexed: 12/11/2022]
Abstract
The transcription factor spalt4 is a key early-response gene in otic placode induction. Here, we characterize the cis-regulatory regions of spalt4 responsible for activation of its expression in the developing otic placode and report the isolation of a novel core enhancer. Identification and mutational analysis of putative transcription factor binding sites reveal that Pea3, a downstream effector of FGF signaling, and Pax2 directly activate spalt4 during ear development. Morpholino-mediated knock-down of each factor reduces or eliminates reporter expression. In contrast, combined over-expression of Pea3 and Pax2 drives ectopic reporter expression, suggesting that they function synergistically. These studies expand the gene regulatory network underlying early otic development by identifying direct inputs that mediate spalt4 expression.
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Affiliation(s)
- Meyer Barembaum
- Division of Biology 139-74, California Institute of Technology, Pasadena, CA 91125, USA
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Park BY, Hong CS, Sohail FA, Saint-Jeannet JP. Developmental expression and regulation of the chemokine CXCL14 in Xenopus. THE INTERNATIONAL JOURNAL OF DEVELOPMENTAL BIOLOGY 2009; 53:535-40. [PMID: 19488965 DOI: 10.1387/ijdb.092855bp] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Chemokines are a family of proteins originally identified for their activity promoting the recruitment of leukocytes to inflammatory sites. Recent evidence indicates that chemokines and their receptors may also regulate key developmental processes. In this paper we report the expression and regulation of the chemokine CXCL14 during Xenopus laevis embryogenesis. CXCL14 is first detected in several ectoderm derivatives, the dorsal aspect of the retina, the cement gland and the hatching gland. Later in development, additional domains of expression include the head mesenchyme and the medial ventral aspect of the otic vesicle. CXCL14 expression in the ectoderm is regulated by both Bmp and canonical Wnt signaling. In the hatching gland CXCL14 is co-expressed with the transcription factor Pax3. Using gain of function and knockdown approaches in whole embryos and animal explants we show that Pax3 is both necessary and sufficient for CXCL14 expression in this domain of the ectoderm.
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Affiliation(s)
- Byung-Yong Park
- Department of Animal Biology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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