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Wang SX, Streit A. Shared features in ear and kidney development - implications for oto-renal syndromes. Dis Model Mech 2024; 17:dmm050447. [PMID: 38353121 PMCID: PMC10886756 DOI: 10.1242/dmm.050447] [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] [Indexed: 02/16/2024] Open
Abstract
The association between ear and kidney anomalies has long been recognized. However, little is known about the underlying mechanisms. In the last two decades, embryonic development of the inner ear and kidney has been studied extensively. Here, we describe the developmental pathways shared between both organs with particular emphasis on the genes that regulate signalling cross talk and the specification of progenitor cells and specialised cell types. We relate this to the clinical features of oto-renal syndromes and explore links to developmental mechanisms.
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Affiliation(s)
- Scarlet Xiaoyan Wang
- Centre for Craniofacial and Regenerative Biology, King's College London, London SE1 9RT, UK
| | - Andrea Streit
- Centre for Craniofacial and Regenerative Biology, King's College London, London SE1 9RT, UK
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2
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Jeong M, Bojkovic K, Sagi V, Stankovic KM. Molecular and Clinical Significance of Fibroblast Growth Factor 2 in Development and Regeneration of the Auditory System. Front Mol Neurosci 2022; 14:757441. [PMID: 35002617 PMCID: PMC8733209 DOI: 10.3389/fnmol.2021.757441] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Accepted: 11/18/2021] [Indexed: 01/25/2023] Open
Abstract
The fibroblast growth factor 2 (FGF2) is a member of the FGF family which is involved in key biological processes including development, cellular proliferation, wound healing, and angiogenesis. Although the utility of the FGF family as therapeutic agents has attracted attention, and FGF2 has been studied in several clinical contexts, there remains an incomplete understanding of the molecular and clinical function of FGF2 in the auditory system. In this review, we highlight the role of FGF2 in inner ear development and hearing protection and present relevant clinical studies for tympanic membrane (TM) repair. We conclude by discussing the future implications of FGF2 as a potential therapeutic agent.
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Affiliation(s)
- Minjin Jeong
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States.,Department of Otolaryngology-Head and Neck Surgery, Massachusetts Eye and Ear and Harvard Medical School, Boston, MA, United States
| | - Katarina Bojkovic
- Department of Otolaryngology-Head and Neck Surgery, Massachusetts Eye and Ear and Harvard Medical School, Boston, MA, United States
| | - Varun Sagi
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States.,University of Minnesota Medical School, Minneapolis, MN, United States
| | - Konstantina M Stankovic
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States.,Department of Otolaryngology-Head and Neck Surgery, Massachusetts Eye and Ear and Harvard Medical School, Boston, MA, United States
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3
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Riley BB. Comparative assessment of Fgf's diverse roles in inner ear development: A zebrafish perspective. Dev Dyn 2021; 250:1524-1551. [PMID: 33830554 DOI: 10.1002/dvdy.343] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 03/26/2021] [Accepted: 03/26/2021] [Indexed: 01/21/2023] Open
Abstract
Progress in understanding mechanisms of inner ear development has been remarkably rapid in recent years. The research community has benefited from the availability of several diverse model organisms, including zebrafish, chick, and mouse. The complexity of the inner ear has proven to be a challenge, and the complexity of the mammalian cochlea in particular has been the subject of intense scrutiny. Zebrafish lack a cochlea and exhibit a number of other differences from amniote species, hence they are sometimes seen as less relevant for inner ear studies. However, accumulating evidence shows that underlying cellular and molecular mechanisms are often highly conserved. As a case in point, consideration of the diverse functions of Fgf and its downstream effectors reveals many similarities between vertebrate species, allowing meaningful comparisons the can benefit the entire research community. In this review, I will discuss mechanisms by which Fgf controls key events in early otic development in zebrafish and provide direct comparisons with chick and mouse.
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Affiliation(s)
- Bruce B Riley
- Biology Department, Texas A&M University, College Station, Texas, USA
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5
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Nikaido M, Navajas Acedo J, Hatta K, Piotrowski T. Retinoic acid is required and Fgf, Wnt, and Bmp signaling inhibit posterior lateral line placode induction in zebrafish. Dev Biol 2017; 431:215-225. [PMID: 28923486 DOI: 10.1016/j.ydbio.2017.09.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 09/12/2017] [Accepted: 09/14/2017] [Indexed: 10/18/2022]
Abstract
The lateral line system is a mechanosensory systems present in aquatic animals. The anterior and posterior lateral lines develop from anterior and posterior lateral line placodes (aLLp and pLLp), respectively. Although signaling molecules required for the induction of other cranial placodes have been well studied, the molecular mechanisms underlying formation of the lateral line placodes are unknown. In this study we tested the requirement of multiple signaling pathways, such as Wnt, Bmp Fgf, and Retinoic Acid for aLLp and pLLp induction. We determined that aLLp specification requires Fgf signaling, whilst pLLp specification requires retinoic acid which inhibits Fgf signaling. pLLp induction is also independent of Wnt and Bmp activities, even though these pathways limit the boundaries of the pLLp. This is the first report that the aLLp and pLLp depend on different inductive mechanisms and that pLLp induction requires the inhibition of Fgf, Wnt and Bmp signaling.
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Affiliation(s)
- Masataka Nikaido
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA; Graduate School of Life Sciences, University of Hyogo, Hyogo Pref. 678-1297, Japan
| | | | - Kohei Hatta
- Graduate School of Life Sciences, University of Hyogo, Hyogo Pref. 678-1297, Japan
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6
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A gene network regulated by FGF signalling during ear development. Sci Rep 2017; 7:6162. [PMID: 28733657 DOI: 10.1038/s41598-017-05472-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Accepted: 05/31/2017] [Indexed: 02/08/2023] Open
Abstract
During development cell commitment is regulated by inductive signals that are tightly controlled in time and space. In response, cells activate specific programmes, but the transcriptional circuits that maintain cell identity in a changing signalling environment are often poorly understood. Specification of inner ear progenitors is initiated by FGF signalling. Here, we establish the genetic hierarchy downstream of FGF by systematic analysis of many ear factors combined with a network inference approach. We show that FGF rapidly activates a small circuit of transcription factors forming positive feedback loops to stabilise otic progenitor identity. Our predictive network suggests that subsequently, transcriptional repressors ensure the transition of progenitors to mature otic cells, while simultaneously repressing alternative fates. Thus, we reveal the regulatory logic that initiates ear formation and highlight the hierarchical organisation of the otic gene network.
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7
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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: 39] [Impact Index Per Article: 4.9] [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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8
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Lee SG, Huang M, Obholzer ND, Sun S, Li W, Petrillo M, Dai P, Zhou Y, Cotanche DA, Megason SG, Li H, Chen ZY. Myc and Fgf Are Required for Zebrafish Neuromast Hair Cell Regeneration. PLoS One 2016; 11:e0157768. [PMID: 27351484 PMCID: PMC4924856 DOI: 10.1371/journal.pone.0157768] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 06/03/2016] [Indexed: 01/05/2023] Open
Abstract
Unlike mammals, the non-mammalian vertebrate inner ear can regenerate the sensory cells, hair cells, either spontaneously or through induction after hair cell loss, leading to hearing recovery. The mechanisms underlying the regeneration are poorly understood. By microarray analysis on a chick model, we show that chick hair cell regeneration involves the activation of proliferation genes and downregulation of differentiation genes. Both MYC and FGF are activated in chick hair cell regeneration. Using a zebrafish lateral line neuromast hair cell regeneration model, we show that the specific inhibition of Myc or Fgf suppresses hair cell regeneration, demonstrating that both pathways are essential to the process. Rapid upregulation of Myc and delayed Fgf activation during regeneration suggest a role of Myc in proliferation and Fgf in differentiation. The dorsal-ventral pattern of fgfr1a in the neuromasts overlaps with the distribution of hair cell precursors. By laser ablation, we show that the fgfr1a-positive supporting cells are likely the hair cell precursors that directly give rise to new hair cells; whereas the anterior-posterior fgfr1a-negative supporting cells have heightened proliferation capacity, likely to serve as more primitive progenitor cells to replenish lost precursors after hair cell loss. Thus fgfr1a is likely to mark compartmentalized supporting cell subtypes with different capacities in renewal proliferation and hair cell regeneration. Manipulation of c-MYC and FGF pathways could be explored for mammalian hair cell regeneration.
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Affiliation(s)
- Sang Goo Lee
- Department of Otolaryngology, Harvard Medical School, Boston, Massachusetts, United States of America
- Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States of America
| | - Mingqian Huang
- Department of Otolaryngology, Harvard Medical School, Boston, Massachusetts, United States of America
- Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States of America
| | - Nikolaus D. Obholzer
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Shan Sun
- Department of Otolaryngology, Harvard Medical School, Boston, Massachusetts, United States of America
- Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States of America
- Department of Otorhinolaryngology, Shanghai Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China
| | - Wenyan Li
- Department of Otolaryngology, Harvard Medical School, Boston, Massachusetts, United States of America
- Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States of America
- Department of Otorhinolaryngology, Shanghai Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China
| | - Marco Petrillo
- Department of Otolaryngology, Harvard Medical School, Boston, Massachusetts, United States of America
- Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States of America
| | - Pu Dai
- Department of Otolaryngology, Chinese PLA General Hospital, Beijing, China
| | - Yi Zhou
- Stem Cell Program and Division of Pediatric Hematology/Oncology, Children’s Hospital Boston and Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
| | - Douglas A. Cotanche
- Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Sean G. Megason
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Huawei Li
- Department of Otorhinolaryngology, Shanghai Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China
- * E-mail: (ZYC); (HL)
| | - Zheng-Yi Chen
- Department of Otolaryngology, Harvard Medical School, Boston, Massachusetts, United States of America
- Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States of America
- * E-mail: (ZYC); (HL)
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9
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Olaya-Sánchez D, Sánchez-Guardado LÓ, Ohta S, Chapman SC, Schoenwolf GC, Puelles L, Hidalgo-Sánchez M. Fgf3 and Fgf16 expression patterns define spatial and temporal domains in the developing chick inner ear. Brain Struct Funct 2016; 222:131-149. [PMID: 26995070 DOI: 10.1007/s00429-016-1205-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 02/19/2016] [Indexed: 11/26/2022]
Abstract
The inner ear is a morphologically complex sensory structure with auditory and vestibular functions. The developing otic epithelium gives rise to neurosensory and non-sensory elements of the adult membranous labyrinth. Extrinsic and intrinsic signals manage the patterning and cell specification of the developing otic epithelium by establishing lineage-restricted compartments defined in turn by differential expression of regulatory genes. FGF3 and FGF16 are excellent candidates to govern these developmental events. Using the chick inner ear, we show that Fgf3 expression is present in the borders of all developing cristae. Strong Fgf16 expression was detected in a portion of the developing vertical and horizontal pouches, whereas the cristae show weaker or undetected Fgf16 expression at different developmental stages. Concerning the rest of the vestibular sensory elements, both the utricular and saccular maculae were Fgf3 positive. Interestingly, strong Fgf16 expression delimited these Fgf16-negative sensory patches. The Fgf3-negative macula neglecta and the Fgf3-positive macula lagena were included within weakly Fgf16-expressing areas. Therefore, different FGF-mediated mechanisms might regulate the specification of the anterior (utricular and saccular) and posterior (neglecta and lagena) maculae. In the developing cochlear duct, dynamic Fgf3 and Fgf16 expression suggests their cooperation in the early specification and later cell differentiation in the hearing system. The requirement of Fgf3 and Fgf16 genes in endolymphatic apparatus development and neurogenesis are discussed. Based on these observations, FGF3 and FGF16 seem to be key signaling pathways that control the inner ear plan by defining epithelial identities within the developing otic epithelium.
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Affiliation(s)
- Daniel Olaya-Sánchez
- Department of Cell Biology, School of Science, University of Extremadura, Avda. de Elvas s/n, 06071, Badajoz, Spain
| | - Luis Óscar Sánchez-Guardado
- Department of Cell Biology, School of Science, University of Extremadura, Avda. de Elvas s/n, 06071, Badajoz, Spain
| | - Sho Ohta
- Department of Neurobiology and Anatomy, University of Utah, 2R066 School of Medicine, 30 N. 1900 E., Salt Lake City, UT, 84132-3401, USA
| | - Susan C Chapman
- Department of Biological Sciences, Clemson University, 340 Long Hall, Clemson, SC, 29634, USA
| | - Gary C Schoenwolf
- Department of Neurobiology and Anatomy, University of Utah, 2R066 School of Medicine, 30 N. 1900 E., Salt Lake City, UT, 84132-3401, USA
| | - Luis Puelles
- Department of Human Anatomy and Psychobiology, School of Medicine, University of Murcia, 30100, Murcia, Spain
| | - Matías Hidalgo-Sánchez
- Department of Cell Biology, School of Science, University of Extremadura, Avda. de Elvas s/n, 06071, Badajoz, Spain.
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10
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Sai X, Ladher RK. Early steps in inner ear development: induction and morphogenesis of the otic placode. Front Pharmacol 2015; 6:19. [PMID: 25713536 PMCID: PMC4322616 DOI: 10.3389/fphar.2015.00019] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2014] [Accepted: 01/21/2015] [Indexed: 01/09/2023] Open
Abstract
Various cellular replacement therapies using in vitro generated cells to replace damaged tissue have been proposed as strategies to alleviate hearing loss. All such therapies must involve a complete understanding of the earliest steps in inner ear development; its induction as a thickened plate of cells in the non-neural, surface ectoderm of the embryo, to its internalization as an otocyst embedded in the head mesenchyme of the embryo. Such knowledge informs researchers addressing the feasibility of the proposed strategy and present alternatives if needed. In this review we describe the mechanisms of inner ear induction, concentrating on the factors that steer the fate of ectoderm into precursors of the inner ear. Induction then leads to inner ear morphogenesis and we describe the cellular changes that occur as the inner ear is converted from a superficial placode to an internalized otocyst, and how they are coordinated with a particular emphasis on how the signaling environment surrounding the inner ear influences these processes.
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Affiliation(s)
- Xiaorei Sai
- Laboratory for Sensory Development, RIKEN Center for Developmental Biology Kobe, Japan
| | - Raj K Ladher
- Laboratory for Sensory Development, RIKEN Center for Developmental Biology Kobe, Japan
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11
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Ma WR, Zhang J. Jag1b is essential for patterning inner ear sensory cristae by regulating anterior morphogenetic tissue separation and preventing posterior cell death. Development 2015; 142:763-73. [DOI: 10.1242/dev.113662] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The sensory patches of the vertebrate inner ear, which contain hair cells and supporting cells, are essential for hearing and balance functions. How the stereotypically organized sensory patches are formed remains to be determined. In this study, we isolated a zebrafish mutant in which the jag1b gene is disrupted by an EGFP insertion. Loss of Jag1b causes cell death in the developing posterior crista and results in downregulation of fgf10a in the posterior prosensory cells. Inhibition of FGFR activity in wild-type embryos also causes loss of the posterior crista, suggesting that Fgf10a mediates Jag1b activity. By contrast, in the anterior prosensory domain, Jag1b regulates separation of a single morphogenetic field into anterior and lateral cristae by flattening cells destined to form a nonsensory epithelium between the two cristae. MAPK activation in the nonsensory epithelium precursors is required for the separation. In the jag1b mutant, MAPK activation and cell flattening are extended to anterior crista primordia, causing loss of anterior crista. More importantly, inhibition of MAPK activity, which blocks the differentiation of nonsensory epithelial cells, generated a fused large crista and extra hair cells. Thus, Jag1b uses two distinct mechanisms to form three sensory cristae in zebrafish.
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Affiliation(s)
- Wei-Rui Ma
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jian Zhang
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
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12
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Foxi3 is necessary for the induction of the chick otic placode in response to FGF signaling. Dev Biol 2014; 391:158-69. [PMID: 24780628 DOI: 10.1016/j.ydbio.2014.04.014] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Revised: 03/19/2014] [Accepted: 04/20/2014] [Indexed: 01/06/2023]
Abstract
Vertebrate cranial sensory organs are derived from region at the border of the anterior neural plate called the pre-placodal region (PPR). The otic placode, the anlagen of the inner ear, is induced from PPR ectoderm by FGF signaling. We have previously shown that competence of embryonic ectoderm to respond to FGF signaling during otic placode induction correlates with the expression of PPR genes, but the molecular basis of this competence is poorly understood. Here, we characterize the function of a transcription factor, Foxi3 that is expressed at very early stages in the non-neural ectoderm and later in the PPR of chick embryos. Ablation experiments showed that the underlying hypoblast is necessary for the initiation of Foxi3 expression. Mis-expression of Foxi3 was sufficient to induce markers of non-neural ectoderm such as Dlx5, and the PPR such as Six1 and Eya2. Electroporation of Dlx5, or Six1 together with Eya1 also induced Foxi3, suggesting direct or indirect positive regulation between non-neural ectoderm genes and PPR genes. Knockdown of Foxi3 in chick embryos prevented the induction of otic placode markers, and was able to prevent competent cranial ectoderm from expressing otic markers in response to FGF2. In contrast, Foxi3 expression alone was not sufficient to confer competence to respond to FGF on embryonic ectoderm. Our analysis of PPR and FGF-responsive genes after Foxi3 knockdown at gastrula stages suggests it is not necessary for the expression of PPR genes at these stages, nor for the transduction of FGF signals. The early expression but late requirement for Foxi3 in ear induction suggests it may have some of the properties associated with pioneer transcription factors.
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13
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Jidigam VK, Gunhaga L. Development of cranial placodes: insights from studies in chick. Dev Growth Differ 2012; 55:79-95. [PMID: 23278869 DOI: 10.1111/dgd.12027] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Revised: 11/02/2012] [Accepted: 11/03/2012] [Indexed: 12/19/2022]
Abstract
This review focuses on how research, using chick as a model system, has contributed to our knowledge regarding the development of cranial placodes. This review highlights when and how molecular signaling events regulate early specification of placodal progenitor cells, as well as the development of individual placodes including morphological movements. In addition, we briefly describe various techniques used in chick that are important for studies in cell and developmental biology.
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Affiliation(s)
- Vijay K Jidigam
- Umeå Centre for Molecular Medicine, Umeå University, Umeå, Sweden
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14
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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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15
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Padanad MS, Bhat N, Guo B, Riley BB. Conditions that influence the response to Fgf during otic placode induction. Dev Biol 2012; 364:1-10. [PMID: 22327005 DOI: 10.1016/j.ydbio.2012.01.022] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Revised: 01/22/2012] [Accepted: 01/26/2012] [Indexed: 01/04/2023]
Abstract
Despite the vital importance of Fgf for otic induction, previous attempts to study otic induction through Fgf misexpression have yielded widely varying and contradictory results. There are also discrepancies regarding the ability of Fgf to induce otic tissue in ectopic locations, raising questions about the sufficiency of Fgf and the degree to which other local factors enhance or restrict otic potential. Using heat shock-inducible transgenes to misexpress Fgf3 or Fgf8 in zebrafish, we found that the stage, distribution and level of misexpression strongly influence the response to Fgf. Fgf misexpression during gastrulation can inhibit or promote otic development, depending on context, whereas misexpression after gastrulation leads to expansion of otic markers throughout preplacodal ectoderm surrounding the head. Elevated Fgf also expands expression of the putative competence factor Foxi1, which is required for Fgf to expand other otic markers. Misexpression of downstream factors Pax2a or Pax8 also expands otic markers but cannot bypass the requirement for Fgf or Foxi1. Co-misexpression of Pax2/8 with Fgf8 potentiates formation of ectopic otic vesicles expressing a full range of otic markers. These findings document the variables critically affecting the response to Fgf and clarify the roles of foxi1 and pax2/8 in the otic response.
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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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16
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Noda T, Oki S, Kitajima K, Harada T, Komune S, Meno C. Restriction of Wnt signaling in the dorsal otocyst determines semicircular canal formation in the mouse embryo. Dev Biol 2011; 362:83-93. [PMID: 22166339 DOI: 10.1016/j.ydbio.2011.11.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2011] [Revised: 11/27/2011] [Accepted: 11/28/2011] [Indexed: 01/07/2023]
Abstract
The mouse inner ear develops from a simple epithelial pouch, the otocyst, with the dorsal and ventral portions giving rise to the vestibule and cochlea, respectively. The otocyst undergoes a morphological change to generate flattened saclike structures, known as outpocketings, in the dorsal and lateral regions. The semicircular canals of the vestibule form from the periphery of the outpocketings, with the central region (the fusion plate) undergoing de-epithelialization and disappearing. However, little is known of the mechanism that orchestrates formation of the semicircular canals. We now show that the area of canonical Wnt signaling changes dynamically in the dorsal otocyst during its morphogenesis. The genes for several Wnt ligands were found to be expressed in the dorsal otocyst according to specific patterns, whereas those for secreted inhibitors of Wnt ligands were expressed exclusively in the ventral otocyst. With the use of whole-embryo culture in combination with potent modulators of canonical Wnt signaling, we found that forced persistence of such signaling resulted in impaired formation both of the lateral outpocketing and of the fusion plates of the dorsal outpocketing. Canonical Wnt signaling was found to suppress Netrin1 expression and to preserve the integrity of the outpocketing epithelium. In addition, inhibition of canonical Wnt signaling reduced the size of the otocyst, likely through suppression of cell proliferation and promotion of apoptosis. Our stage-specific functional analysis suggests that strict regulation of canonical Wnt signaling in the dorsal otocyst orchestrates the process of semicircular canal formation.
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Affiliation(s)
- Teppei Noda
- Department of Developmental Biology, Graduate School of Medical Sciences, Kyushu University, Higashi-ku, Fukuoka, Japan
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17
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Robert-Moreno À, Naranjo S, de la Calle-Mustienes E, Gómez-Skarmeta JL, Alsina B. Characterization of new otic enhancers of the pou3f4 gene reveal distinct signaling pathway regulation and spatio-temporal patterns. PLoS One 2010; 5:e15907. [PMID: 21209840 PMCID: PMC3013142 DOI: 10.1371/journal.pone.0015907] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Accepted: 11/26/2010] [Indexed: 02/01/2023] Open
Abstract
POU3F4 is a member of the POU-homedomain transcription factor family with a prominent role in inner ear development. Mutations in the human POU3F4 coding unit leads to X-linked deafness type 3 (DFN3), characterized by conductive hearing loss and progressive sensorineural deafness. Microdeletions found 1 Mb 5' upstream of the coding region also displayed the same phenotype, suggesting that cis-regulatory elements might be present in that region. Indeed, we and others have recently identified several enhancers at the 1 Mb 5' upstream interval of the pou3f4 locus. Here we characterize the spatio-temporal patterns of these regulatory elements in zebrafish transgenic lines. We show that the most distal enhancer (HCNR 81675) is activated earlier and drives GFP reporter expression initially to a broad ear domain to progressively restrict to the sensory patches. The proximal enhancer (HCNR 82478) is switched later during development and promotes expression, among in other tissues, in sensory patches from its onset. The third enhancer (HCNR 81728) is also active at later stages in the otic mesenchyme and in the otic epithelium. We also characterize the signaling pathways regulating these enhancers. While HCNR 81675 is regulated by very early signals of retinoic acid, HCNR 82478 is regulated by Fgf activity at a later stage and the HCNR 81728 enhancer is under the control of Hh signaling. Finally, we show that Sox2 and Pax2 transcription factors are bound to HCNR 81675 genomic region during otic development and specific mutations to these transcription factor binding sites abrogates HCNR 81675 enhancer activity. Altogether, our results suggest that pou3f4 expression in inner ear might be under the control of distinct regulatory elements that fine-tune the spatio-temporal activity of this gene and provides novel data on the signaling mechanisms controlling pou3f4 function.
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Affiliation(s)
- Àlex Robert-Moreno
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra/Parc de Recerca Biomèdica de Barcelona, Barcelona, Spain
| | - Silvia Naranjo
- Centro Andaluz de Biología del Desarrollo, CSIC/Universidad Pablo de Olavide, Sevilla, Spain
| | | | | | - Berta Alsina
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra/Parc de Recerca Biomèdica de Barcelona, Barcelona, Spain
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18
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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: 112] [Impact Index Per Article: 8.0] [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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19
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Oshima K, Shin K, Diensthuber M, Peng AW, Ricci AJ, Heller S. Mechanosensitive hair cell-like cells from embryonic and induced pluripotent stem cells. Cell 2010; 141:704-16. [PMID: 20478259 DOI: 10.1016/j.cell.2010.03.035] [Citation(s) in RCA: 220] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2009] [Revised: 01/18/2010] [Accepted: 02/24/2010] [Indexed: 12/21/2022]
Abstract
Mechanosensitive sensory hair cells are the linchpin of our senses of hearing and balance. The inability of the mammalian inner ear to regenerate lost hair cells is the major reason for the permanence of hearing loss and certain balance disorders. Here, we present a stepwise guidance protocol starting with mouse embryonic stem and induced pluripotent stem cells, which were directed toward becoming ectoderm capable of responding to otic-inducing growth factors. The resulting otic progenitor cells were subjected to varying differentiation conditions, one of which promoted the organization of the cells into epithelial clusters displaying hair cell-like cells with stereociliary bundles. Bundle-bearing cells in these clusters responded to mechanical stimulation with currents that were reminiscent of immature hair cell transduction currents.
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Affiliation(s)
- Kazuo Oshima
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA
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20
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Independent regulation of Sox3 and Lmx1b by FGF and BMP signaling influences the neurogenic and non-neurogenic domains in the chick otic placode. Dev Biol 2010; 339:166-78. [DOI: 10.1016/j.ydbio.2009.12.027] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2009] [Revised: 11/30/2009] [Accepted: 12/18/2009] [Indexed: 01/02/2023]
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21
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Krejci P, Prochazkova J, Bryja V, Kozubik A, Wilcox WR. Molecular pathology of the fibroblast growth factor family. Hum Mutat 2009; 30:1245-55. [PMID: 19621416 DOI: 10.1002/humu.21067] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The human fibroblast growth factor (FGF) family contains 22 proteins that regulate a plethora of physiological processes in both developing and adult organism. The mutations in the FGF genes were not known to play role in human disease until the year 2000, when mutations in FGF23 were found to cause hypophosphatemic rickets. Nine years later, seven FGFs have been associated with human disorders. These include FGF3 in Michel aplasia; FGF8 in cleft lip/palate and in hypogonadotropic hypogonadism; FGF9 in carcinoma; FGF10 in the lacrimal/salivary glands aplasia, and lacrimo-auriculo-dento-digital syndrome; FGF14 in spinocerebellar ataxia; FGF20 in Parkinson disease; and FGF23 in tumoral calcinosis and hypophosphatemic rickets. The heterogeneity in the functional consequences of FGF mutations, the modes of inheritance, pattern of involved tissues/organs, and effects in different developmental stages provide fascinating insights into the physiology of the FGF signaling system. We review the current knowledge about the molecular pathology of the FGF family.
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Affiliation(s)
- Pavel Krejci
- Department of Immunology and Animal Physiology, Institute of Experimental Biology, Masaryk University, Brno, Czech Republic.
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22
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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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23
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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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24
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Domínguez-Frutos E, Vendrell V, Alvarez Y, Zelarayan LC, López-Hernández I, Ros M, Schimmang T. Tissue-specific requirements for FGF8 during early inner ear development. Mech Dev 2009; 126:873-81. [DOI: 10.1016/j.mod.2009.07.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2008] [Revised: 07/13/2009] [Accepted: 07/14/2009] [Indexed: 11/15/2022]
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25
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Molecular and tissue interactions governing induction of cranial ectodermal placodes. Dev Biol 2009; 332:189-95. [PMID: 19500565 DOI: 10.1016/j.ydbio.2009.05.572] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2009] [Revised: 05/27/2009] [Accepted: 05/28/2009] [Indexed: 12/31/2022]
Abstract
Whereas neural crest cells are the source of the peripheral nervous system in the trunk of vertebrates, the "ectodermal placodes," together with neural crest, form the peripheral nervous system of the head. Cranial ectodermal placodes are thickenings in the ectoderm that subsequently ingress or invaginate to make important contributions to cranial ganglia, including epibranchial and trigeminal ganglia, and sensory structures, the ear, nose, lens, and adenohypophysis. Recent studies have uncovered a number of molecular signals mediating induction and differentiation of placodal cells. Here, we described recent advances in understanding the tissue interactions and signals underlying induction and neurogenesis of placodes, with emphasis on the trigeminal and epibranchial. Important roles of Fibroblast Growth Factors, Platelet Derived Growth Factors, Sonic Hedgehog, TGFbeta superfamily members, and Wnts are discussed.
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26
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Park BY, Saint-Jeannet JP. Hindbrain-derived Wnt and Fgf signals cooperate to specify the otic placode in Xenopus. Dev Biol 2008; 324:108-21. [PMID: 18831968 DOI: 10.1016/j.ydbio.2008.09.009] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2008] [Revised: 08/29/2008] [Accepted: 09/08/2008] [Indexed: 11/30/2022]
Abstract
Induction of the otic placode, the rudiment of the inner ear, is believed to depend on signals derived from surrounding tissues, the head mesoderm and the prospective hindbrain. Here we report the first attempt to define the specific contribution of the neuroectoderm to this inductive process in Xenopus. To this end we tested the ability of segments of the neural plate (NP), isolated from different axial levels, to induce the otic marker Pax8 when recombined with blastula stage animal caps. We found that one single domain of the NP, corresponding to the prospective anterior hindbrain, had Pax8-inducing activity in this assay. Surprisingly, more than half of these recombinants formed otic vesicle-like structures. Lineage tracing experiments indicate that these vesicle-like structures are entirely derived from the animal cap and express several pan-otic markers. Pax8 activation in these recombinants requires active Fgf and canonical Wnt signaling, as interference with either pathway blocks Pax8 induction. Furthermore, we demonstrate that Fgf and canonical Wnt signaling cooperate to activate Pax8 expression in isolated animal caps. We propose that in the absence of mesoderm cues the combined activity of hindbrain-derived Wnt and Fgf signals specifies the otic placode in Xenopus, and promotes its morphogenesis into an otocyst.
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Affiliation(s)
- Byung-Yong Park
- Department of Animal Biology, School of Veterinary Medicine, University of Pennsylvania, 3800 Spruce Street, Philadelphia, PA 19104, USA
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27
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Zelarayan LC, Vendrell V, Alvarez Y, Domínguez-Frutos E, Theil T, Alonso MT, Maconochie M, Schimmang T. Differential requirements for FGF3, FGF8 and FGF10 during inner ear development. Dev Biol 2007; 308:379-91. [PMID: 17601531 DOI: 10.1016/j.ydbio.2007.05.033] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2006] [Revised: 05/21/2007] [Accepted: 05/24/2007] [Indexed: 02/02/2023]
Abstract
FGF signaling is required during multiple stages of inner ear development in many different vertebrates, where it is involved in induction of the otic placode, in formation and morphogenesis of the otic vesicle as well as for cellular differentiation within the sensory epithelia. In this study we have looked to define the redundant and conserved roles of FGF3, FGF8 and FGF10 during the development of the murine and avian inner ear. In the mouse, hindbrain-derived FGF10 ectopically induces FGF8 and rescues otic vesicle formation in Fgf3 and Fgf10 homozygous double mutants. Conditional inactivation of Fgf8 after induction of the placode does not interfere with otic vesicle formation and morphogenesis but affects cellular differentiation in the inner ear. In contrast, inactivation of Fgf8 during induction of the placode in a homozygous Fgf3 null background leads to a reduced size otic vesicle or the complete absence of otic tissue. This latter phenotype is more severe than the one observed in mutants carrying null mutations for both Fgf3 and Fgf10 that develop microvesicles. However, FGF3 and FGF10 are redundantly required for morphogenesis of the otic vesicle and the formation of semicircular ducts. In the chicken embryo, misexpression of Fgf3 in the hindbrain induces ectopic otic vesicles in vivo. On the other hand, Fgf3 expression in the hindbrain or pharyngeal endoderm is required for formation of the otic vesicle from the otic placode. Together these results provide important insights into how the spatial and temporal expression of various FGFs controls different steps of inner ear formation during vertebrate development.
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Affiliation(s)
- Laura Cecilia Zelarayan
- Center for Molecular Neurobiology, University of Hamburg, Falkenried 94, D-20251 Hamburg, Germany
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28
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Aghaallaei N, Bajoghli B, Czerny T. Distinct roles of Fgf8, Foxi1, Dlx3b and Pax8/2 during otic vesicle induction and maintenance in medaka. Dev Biol 2007; 307:408-20. [PMID: 17555740 DOI: 10.1016/j.ydbio.2007.04.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2006] [Revised: 04/16/2007] [Accepted: 04/17/2007] [Indexed: 10/23/2022]
Abstract
The development of the vertebrate inner ear is a complex process that has been investigated in several model organisms. In this work, we examined genetic interactions regulating early development of otic structures in medaka. We demonstrate that misexpression of Fgf8, Dlx3b and Foxi1 during early gastrulation is sufficient to produce ectopic otic vesicles. Combined misexpression strongly increases the appearance of this phenotype. By using a heat-inducible promoter we were furthermore able to separate the regulatory interactions among Fgf8, Foxi1, Dlx3b, Pax8 and Pax2 genes, which are active during different stages of early otic development. In the preplacodal stage we suggest a central position of Foxi1 within a regulatory network of early patterning genes including Dlx3b and Pax8. Different pathways are active after the placodal stage with Dlx3b playing a central role. There Dlx3b regulates members of the Pax-Six-Eya-Dach network and also strongly affects the early dorsoventral marker genes Otx1 and Gbx2.
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Affiliation(s)
- Narges Aghaallaei
- Institute of Animal Breeding and Genetics, University of Veterinary Medicine, Veterinärplatz 1, A-1210 Vienna, Austria
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29
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Tekin M, Hişmi BO, Fitoz S, Ozdağ H, Cengiz FB, Sirmaci A, Aslan I, Inceoğlu B, Yüksel-Konuk EB, Yilmaz ST, Yasun O, Akar N. Homozygous mutations in fibroblast growth factor 3 are associated with a new form of syndromic deafness characterized by inner ear agenesis, microtia, and microdontia. Am J Hum Genet 2007; 80:338-44. [PMID: 17236138 PMCID: PMC1785350 DOI: 10.1086/510920] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2006] [Accepted: 11/15/2006] [Indexed: 11/03/2022] Open
Abstract
We identified nine individuals from three unrelated Turkish families with a unique autosomal recessive syndrome characterized by type I microtia, microdontia, and profound congenital deafness associated with a complete absence of inner ear structures (Michel aplasia). We later demonstrated three different homozygous mutations (p.S156P, p.R104X, and p.V206SfsX117) in the fibroblast growth factor 3 (FGF3) gene in affected members of these families, cosegregating with the autosomal recessive transmission as a completely penetrant phenotype. These findings demonstrate the involvement of FGF3 mutations in a human malformation syndrome for the first time and contribute to our understanding of the role this gene plays in embryonic development. Of particular interest is that the development of the inner ear is completely disturbed at a very early stage--or the otic vesicle is not induced at all--in all of the affected individuals who carried two mutant FGF3 alleles.
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Affiliation(s)
- Mustafa Tekin
- Division of Clinical Molecular Pathology and Genetics, Department of Pediatrics, Ankara University School of Medicine, Ankara, Turkey.
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30
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Fgf-dependent otic induction requires competence provided by Foxi1 and Dlx3b. BMC DEVELOPMENTAL BIOLOGY 2007; 7:5. [PMID: 17239227 PMCID: PMC1794237 DOI: 10.1186/1471-213x-7-5] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/01/2006] [Accepted: 01/19/2007] [Indexed: 01/21/2023]
Abstract
Background The inner ear arises from a specialized set of cells, the otic placode, that forms at the lateral edge of the neural plate adjacent to the hindbrain. Previous studies indicated that fibroblast growth factors (Fgfs) are required for otic induction; in zebrafish, loss of both Fgf3 and Fgf8 results in total ablation of otic tissue. Furthermore, gain-of-function studies suggested that Fgf signaling is not only necessary but also sufficient for otic induction, although the amount of induced ectopic otic tissue reported after misexpression of fgf3 or fgf8 varies among different studies. We previously suggested that Foxi1 and Dlx3b may provide competence to form the ear because loss of both foxi1 and dlx3b results in ablation of all otic tissue even in the presence of a fully functional Fgf signaling pathway. Results Using a transgenic line that allows us to misexpress fgf8 under the control of the zebrafish temperature-inducible hsp70 promoter, we readdressed the role of Fgf signaling and otic competence during placode induction. We find that misexpression of fgf8 fails to induce formation of ectopic otic vesicles outside of the endogenous ear field and has different consequences depending upon the developmental stage. Overexpression of fgf8 from 1-cell to midgastrula stages leads to formation of no or small otic vesicles, respectively. Overexpression of fgf8 at these stages never leads to ectopic expression of foxi1 or dlx3b, contrary to previous studies that indicated that foxi1 is activated by Fgf signaling. Consistent with our results we find that pharmacological inhibition of Fgf signaling has no effect on foxi1 or dlx3b expression, but instead, Bmp signaling activates foxi1, directly and dlx3b, indirectly. In contrast to early activation of fgf8, fgf8 overexpression at the end of gastrulation, when otic induction begins, leads to much larger otic vesicles. We further show that application of a low dose of retinoic acid that does not perturb patterning of the anterior neural plate leads to expansion of foxi1 and to a massive Fgf-dependent otic induction. Conclusion These results provide further support for the hypothesis that Foxi1 and Dlx3b provide competence for cells to respond to Fgf and form an otic placode.
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31
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Sun SK, Dee CT, Tripathi VB, Rengifo A, Hirst CS, Scotting PJ. Epibranchial and otic placodes are induced by a common Fgf signal, but their subsequent development is independent. Dev Biol 2006; 303:675-86. [PMID: 17222818 DOI: 10.1016/j.ydbio.2006.12.008] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2006] [Revised: 11/30/2006] [Accepted: 12/05/2006] [Indexed: 12/11/2022]
Abstract
The epibranchial placodes are cranial, ectodermal thickenings that give rise to sensory neurons of the peripheral nervous system. Despite their importance in the developing animal, the signals responsible for their induction remain unknown. Using the placodal marker, sox3, we have shown that the same Fgf signaling required for otic vesicle development is required for the development of the epibranchial placodes. Loss of both Fgf3 and Fgf8 is sufficient to block placode development. We further show that epibranchial sox3 expression is unaffected in mutants in which no otic placode forms, where dlx3b and dlx4b are knocked down, or deleted along with sox9a. However, the forkhead factor, Foxi1, is required for both otic and epibranchial placode development. Thus, both the otic and epibranchial placodes form in a common region of ectoderm under the influence of Fgfs, but these two structures subsequently develop independently. Although previous studies have investigated the signals that trigger neurogenesis from the epibranchial placodes, this represents the first demonstration of the signaling events that underlie the formation of the placodes themselves, and therefore, the process that determines which ectodermal cells will adopt a neural fate.
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Affiliation(s)
- Shun-Kuo Sun
- Children's Brain Tumour Research Centre, Institute of Genetics, Queen's Medical Centre, University of Nottingham, Nottingham, NG7 2UH, UK
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32
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Hochmann S, Aghaallaei N, Bajoghli B, Soroldoni D, Carl M, Czerny T. Expression of marker genes during early ear development in medaka. Gene Expr Patterns 2006; 7:355-62. [PMID: 16950663 DOI: 10.1016/j.modgep.2006.07.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2006] [Revised: 07/19/2006] [Accepted: 07/21/2006] [Indexed: 01/26/2023]
Abstract
Induction of the otic placode involves a number of regulatory interactions. Early studies revealed that the induction of this program is initiated by instructive signals from the mesendoderm as well as from the adjacent hindbrain. Further investigations on the molecular level identified in zebrafish Fgf3, Fgf8, Foxi1, Pax8, Dlx3b and Dlx4b genes as key players during the induction phase. Thereafter an increasing number of genes participates in the regulatory interactions finally resulting in a highly structured sensory organ. Based on data from zebrafish we selected medaka genes with presumptive functions during early ear development for an expression analysis. In addition we isolated Foxi1 and Dlx3b gene fragments from embryonic cDNA. Altogether we screened the spatio-temporal distribution of more than 20 representative marker genes for otic development in medaka embryos, with special emphasis on the early phases. Whereas the spatial distribution of these genes is largely conserved between medaka and zebrafish, our comparative analysis revealed several differences, in particular for the timing of expression.
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Affiliation(s)
- Sarah Hochmann
- Institute of Animal Breeding and Genetics, University of Veterinary Medicine, Veterinarplatz 1, A-1210 Vienna, Austria
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33
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Schlosser G. Induction and specification of cranial placodes. Dev Biol 2006; 294:303-51. [PMID: 16677629 DOI: 10.1016/j.ydbio.2006.03.009] [Citation(s) in RCA: 280] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2005] [Revised: 12/22/2005] [Accepted: 12/23/2005] [Indexed: 12/17/2022]
Abstract
Cranial placodes are specialized regions of the ectoderm, which give rise to various sensory ganglia and contribute to the pituitary gland and sensory organs of the vertebrate head. They include the adenohypophyseal, olfactory, lens, trigeminal, and profundal placodes, a series of epibranchial placodes, an otic placode, and a series of lateral line placodes. After a long period of neglect, recent years have seen a resurgence of interest in placode induction and specification. There is increasing evidence that all placodes despite their different developmental fates originate from a common panplacodal primordium around the neural plate. This common primordium is defined by the expression of transcription factors of the Six1/2, Six4/5, and Eya families, which later continue to be expressed in all placodes and appear to promote generic placodal properties such as proliferation, the capacity for morphogenetic movements, and neuronal differentiation. A large number of other transcription factors are expressed in subdomains of the panplacodal primordium and appear to contribute to the specification of particular subsets of placodes. This review first provides a brief overview of different cranial placodes and then synthesizes evidence for the common origin of all placodes from a panplacodal primordium. The role of various transcription factors for the development of the different placodes is addressed next, and it is discussed how individual placodes may be specified and compartmentalized within the panplacodal primordium. Finally, tissues and signals involved in placode induction are summarized with a special focus on induction of the panplacodal primordium itself (generic placode induction) and its relation to neural induction and neural crest induction. Integrating current data, new models of generic placode induction and of combinatorial placode specification are presented.
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Affiliation(s)
- Gerhard Schlosser
- Brain Research Institute, AG Roth, University of Bremen, FB2, 28334 Bremen, Germany.
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34
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Schlosser G. Development and evolution of lateral line placodes in amphibians I. Development. ZOOLOGY 2006; 105:119-46. [PMID: 16351862 DOI: 10.1078/0944-2006-00058] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2002] [Accepted: 05/30/2002] [Indexed: 11/18/2022]
Abstract
Lateral line placodes are specialized regions of the ectoderm that give rise to the receptor organs of the lateral line system as well as to the sensory neurons innervating them. The development of lateral line placodes has been studied in amphibians since the early 1900s. This paper reviews these older studies and tries to integrate them with more recent findings. Lateral line placodes are probably induced in a multistep process from a panplacodal area surrounding the neural plate. The time schedule of these inductive processes has begun to be unravelled, but little is known yet about their molecular basis. Subsequent pattern formation, morphogenesis and differentiation of lateral line placodes proceeds in most respects relatively autonomously: Onset and polarity of migration of lateral line primordia, the type, spacing, size and number of receptor organs formed, as well as the patterned differentiation of different cell types occur normally even in ectopic locations. Only the pathways for migration of lateral line primordia depend on external cues. Thus, lateral line placodes act as integrated and relatively context-insensitive developmental modules.
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35
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Kil SH, Streit A, Brown ST, Agrawal N, Collazo A, Zile MH, Groves AK. Distinct roles for hindbrain and paraxial mesoderm in the induction and patterning of the inner ear revealed by a study of vitamin-A-deficient quail. Dev Biol 2005; 285:252-71. [PMID: 16039643 DOI: 10.1016/j.ydbio.2005.05.044] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2005] [Revised: 05/25/2005] [Accepted: 05/25/2005] [Indexed: 01/22/2023]
Abstract
The hindbrain and cranial paraxial mesoderm have been implicated in the induction and patterning of the inner ear, but the precise role of the two tissues in these processes is still not clear. We have addressed these questions using the vitamin-A-deficient (VAD) quail model, in which VAD embryos lack the posterior half of the hindbrain that normally lies next to the inner ear. Using a battery of molecular markers, we show that the anlagen of the inner ear, the otic placode, is induced in VAD embryos in the absence of the posterior hindbrain. By performing grafting and ablation experiments in chick embryos, we also show that cranial paraxial mesoderm which normally lies beneath the presumptive otic placode is necessary for otic placode induction and that paraxial mesoderm from other locations cannot induce the otic placode. Two members of the fibroblast growth factor family, FGF3 and FGF19, continue to be expressed in this mesodermal population in VAD embryos, and these may be responsible for otic placode induction in the absence of the posterior hindbrain. Although the posterior hindbrain is not required for otic placode induction in VAD embryos, the subsequent patterning of the inner ear is severely disrupted. Several regional markers of the inner ear, such as Pax2, EphA4, SOHo1 and Wnt3a, are incorrectly expressed in VAD otocysts, and the sensory patches and vestibulo-acoustic ganglia are either greatly reduced or absent. Exogenous application of retinoic acid prior to 30 h of development is able rescue the VAD phenotype. By performing such rescue experiments before and after 30 h of development, we show that the inner ear defects of VAD embryos correlate with the absence of the posterior hindbrain. These results show that induction and patterning of the inner ear are governed by separate developmental processes that can be experimentally uncoupled from each other.
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Affiliation(s)
- Sung-Hee Kil
- Gonda Department of Cell and Molecular Biology, House Ear Institute, 2100 West 3rd Street, Los Angeles, CA 90057, USA
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Bajoghli B, Aghaallaei N, Czerny T. Groucho corepressor proteins regulate otic vesicle outgrowth. Dev Dyn 2005; 233:760-71. [PMID: 15861392 DOI: 10.1002/dvdy.20398] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The Groucho/Tle family of corepressor proteins is known to regulate multiple developmental pathways. Applying the dominant-negative effect of the short member Aes, we demonstrate here a critical role of this gene family also for ear development. Misexpression of Aes in medaka embryos resulted in reduced size or loss of otic vesicles, whereas overexpression of the full-length Groucho protein Tle4 gave the opposite phenotype. These results are in close agreement with phenotypes observed for eye formation, suggesting a similar role for Groucho/Tle proteins in the developmental pathways of both sensory organs. Furthermore, by using the heat-inducible HSE promoter, we observed reversible branching of the embryonic axis upon Aes misexpression, indicating a transient duplication of the organizer. Groucho proteins, therefore, are critical for organizer maintenance.
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Affiliation(s)
- Baubak Bajoghli
- Institute of Animal Breeding and Genetics, University of Veterinary Medicine, Vienna, Austria
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Schlosser G. Evolutionary origins of vertebrate placodes: insights from developmental studies and from comparisons with other deuterostomes. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2005; 304:347-99. [PMID: 16003766 DOI: 10.1002/jez.b.21055] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Ectodermal placodes comprise the adenohypophyseal, olfactory, lens, profundal, trigeminal, otic, lateral line, and epibranchial placodes. The first part of this review presents a brief overview of placode development. Placodes give rise to a variety of cell types and contribute to many sensory organs and ganglia of the vertebrate head. While different placodes differ with respect to location and derivative cell types, all appear to originate from a common panplacodal primordium, induced at the anterior neural plate border by a combination of mesodermal and neural signals and defined by the expression of Six1, Six4, and Eya genes. Evidence from mouse and zebrafish mutants suggests that these genes promote generic placodal properties such as cell proliferation, cell shape changes, and specification of neurons. The common developmental origin of placodes suggests that all placodes may have evolved in several steps from a common precursor. The second part of this review summarizes our current knowledge of placode evolution. Although placodes (like neural crest cells) have been proposed to be evolutionary novelties of vertebrates, recent studies in ascidians and amphioxus have proposed that some placodes originated earlier in the chordate lineage. However, while the origin of several cellular and molecular components of placodes (e.g., regionalized expression domains of transcription factors and some neuronal or neurosecretory cell types) clearly predates the origin of vertebrates, there is presently little evidence that these components are integrated into placodes in protochordates. A scenario is presented according to which all placodes evolved from an adenohypophyseal-olfactory protoplacode, which may have originated in the vertebrate ancestor from the anlage of a rostral neurosecretory organ (surviving as Hatschek's pit in present-day amphioxus).
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Ladher RK, Wright TJ, Moon AM, Mansour SL, Schoenwolf GC. FGF8 initiates inner ear induction in chick and mouse. Genes Dev 2005; 19:603-13. [PMID: 15741321 PMCID: PMC551580 DOI: 10.1101/gad.1273605] [Citation(s) in RCA: 153] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
In both chick and mouse, the otic placode, the rudiment of the inner ear, is induced by at least two signals, one from the cephalic paraxial mesoderm and the other from the neural ectoderm. In chick, the mesodermal signal, FGF19, induces neural ectoderm to express additional signals, including WNT8c and FGF3, resulting in induction of the otic placode. In mouse, mesodermal Fgf10 acting redundantly with neural Fgf3 is required for induction of the placode. To determine how the mesodermal inducers of the otic placode are localized, we took advantage of the unique strengths of the two model organisms. We show that endoderm is necessary for otic induction in the chick and that Fgf8, expressed in the chick endoderm subjacent to Fgf19, is both sufficient and necessary for the expression of Fgf19 in the mesoderm. In the mouse, Fgf8 is also expressed in endoderm as well as in other germ layers in the periotic placode region. We show that otic induction fails in embryos null for Fgf3 and hypomorphic for Fgf8 and expression of mesodermal Fgf10 is reduced. Thus, Fgf8 plays a critical upstream role in an FGF signaling cascade required for otic induction in chick and mouse.
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Affiliation(s)
- Raj K Ladher
- Sensory Development, Riken Center for Developmental Biology, Chuo-ku, Kobe 650-0047, Japan.
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Cornesse Y, Pieler T, Hollemann T. Olfactory and lens placode formation is controlled by the hedgehog-interacting protein (Xhip) in Xenopus. Dev Biol 2005; 277:296-315. [PMID: 15617676 DOI: 10.1016/j.ydbio.2004.09.016] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2004] [Revised: 09/08/2004] [Accepted: 09/09/2004] [Indexed: 11/16/2022]
Abstract
The integration of multiple signaling pathways is a key issue in several aspects of embryonic development. In this context, extracellular inhibitors of secreted growth factors play an important role, which is to antagonize specifically the activity of the corresponding signaling molecule. We provide evidence that the Hedgehog-interacting protein (Hip) from Xenopus, previously described as a Hedgehog-specific antagonist in the mouse, interferes with Wnt-8 and eFgf/Fgf-8 signaling pathways as well. To address the function of Hip during early embryonic development, we performed gain- and loss-of-function studies in the frog. Overexpression of Xhip or mHip1 resulted in a dramatic increase of retinal structures and larger olfactory placodes primarily at the expense of other brain tissues. Furthermore, loss of Xhip function resulted in a suppression of olfactory and lens placode formation. Therefore, the localized expression of Xhip may counteract certain overlapping signaling activities, which inhibit the induction of distinct sensory placodes.
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Affiliation(s)
- Yvonne Cornesse
- Department of Developmental Biochemistry, Institute of Biochemistry and Molecular Cell Biology, Georg-August-University of Göttingen, D-37077 Göttingen, Germany
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Streit A. Early development of the cranial sensory nervous system: from a common field to individual placodes. Dev Biol 2005; 276:1-15. [PMID: 15531360 DOI: 10.1016/j.ydbio.2004.08.037] [Citation(s) in RCA: 136] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2004] [Revised: 08/20/2004] [Accepted: 08/23/2004] [Indexed: 01/12/2023]
Abstract
Sensory placodes are unique columnar epithelia with neurogenic potential that develop in the vertebrate head ectoderm next to the neural tube. They contribute to the paired sensory organs and the cranial sensory ganglia generating a wide variety of cell types ranging from lens fibres to sensory receptor cells and neurons. Although progress has been made in recent years to identify the molecular players that mediate placode specification, induction and patterning, the processes that initiate placode development are not well understood. One hypothesis suggests that all placode precursors arise from a common territory, the pre-placodal region, which is then subdivided to generate placodes of specific character. This model implies that their induction begins through molecular and cellular mechanisms common to all placodes. Embryological and molecular evidence suggests that placode induction is a multi-step process and that the molecular networks establishing the pre-placodal domain as well as the acquisition of placodal identity are surprisingly similar to those used in Drosophila to specify sensory structures.
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Affiliation(s)
- Andrea Streit
- Department of Craniofacial Development, King's College London, Guy's Campus, London SE1 9RT, UK.
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Ohuchi H, Yasue A, Ono K, Sasaoka S, Tomonari S, Takagi A, Itakura M, Moriyama K, Noji S, Nohno T. Identification ofcis-element regulating expression of the mouseFgf10 gene during inner ear development. Dev Dyn 2005; 233:177-87. [PMID: 15765517 DOI: 10.1002/dvdy.20319] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Fibroblast growth factor (FGF) signaling is crucial for the induction and growth of the ear, a sensory organ that involves intimate tissue interactions. Here, we report the abnormality of Fgf10 null ear and the identification of a cis-regulatory element directing otic expression of Fgf10. In Fgf10 null inner ears, we found that the initial development of semicircular, vestibular, and cochlear divisions is roughly normal, after which there are abnormalities of semicircular canal/cristae and vestibular development. The mutant semicircular disks remain without canal formation by the perinatal stage. To elucidate regulation of the Fgf10 expression during inner ear development, we isolated a 6.6-kb fragment of its 5'-upstream region and examined its transcriptional activity with transgenic mice, using a lacZ-reporter system. From comparison of the mouse sequences of the 6.6-kb fragment with corresponding sequences of the human and chicken Fgf10, we identified a 0.4-kb enhancer sequence that drives Fgf10 expression in the developing inner ear. The enhancer sequences have motifs for many homeodomain-containing proteins (e.g., Prx, Hox, Nkx), in addition to POU-domain factors (e.g., Brn3), zinc-finger transcription factors (e.g., GATA-binding factors), TCF/LEF-1, and a SMAD-interacting protein. Thus, FGF10 signaling is dispensable for specification of otic compartment identity but is required for hollowing the semicircular disk. Furthermore, the analysis of a putative inner ear enhancer of Fgf10 has disclosed a complicated regulation of Fgf10 during inner ear development by numerous transcription factors and signaling pathways.
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Affiliation(s)
- Hideyo Ohuchi
- Department of Biological Science and Technology, Faculty of Engineering, University of Tokushima, 2-1 Minami-Jyosanjima-cho, Tokushima City 770-8506, Japan.
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42
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Solomon KS, Kwak SJ, Fritz A. Genetic interactions underlying otic placode induction and formation. Dev Dyn 2004; 230:419-33. [PMID: 15188428 DOI: 10.1002/dvdy.20067] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The formation of the otic placode is a complex process requiring multiple inductive signals. In zebrafish, fgf3 and fgf8, dlx3b and dlx4b, and foxi1 have been identified as the earliest-acting genes in this process. fgf3 and fgf8 are required as inductive signals, whereas dlx3b, dlx4b, and foxi1 appear to act directly within otic primordia. We have investigated potential interactions among these genes. Depletion of either dlx3b and dlx4b or foxi1 leads to a delay of pax2a expression in the otic primordia and reduction of the otic vesicle. Depletion of both foxi1 and dlx3b results in a complete ablation of otic placode formation. A strong synergistic interaction is also observed among foxi1, fgf3, and fgf8, and a weaker interaction among dlx3b, fgf3, and fgf8. Misexpression of foxi1 can induce expression of pax8, an early marker for the otic primordia, in embryos treated with an inhibitor of fibroblast growth factor (FGF) signaling. Conversely, morpholino knockdown of foxi1 blocks ectopic pax8 expression and otic vesicle formation induced by misexpression of fgf3 and/or fgf8. The observed genetic interactions suggest a model in which foxi1 and dlx3b/dlx4b act in independent pathways together with distinct phases of FGF signaling to promote otic placode induction and development.
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Affiliation(s)
- Keely S Solomon
- Department of Biology, Emory University, Atlanta, Georgia, USA
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Bajoghli B, Aghaallaei N, Heimbucher T, Czerny T. An artificial promoter construct for heat-inducible misexpression during fish embryogenesis. Dev Biol 2004; 271:416-30. [PMID: 15223344 DOI: 10.1016/j.ydbio.2004.04.006] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2004] [Revised: 04/13/2004] [Accepted: 04/15/2004] [Indexed: 11/21/2022]
Abstract
Beside spatial distribution, timing of gene expression is a key parameter controlling gene function during embryonic development. Gain-of-function experiments can therefore have quite opposing results, depending on the time of gene activation. Induction techniques are necessary to control timing in these experiments from outside of the organism. Natural heat shock promoters constitute a simple inducible misexpression system, the main disadvantage is a high background level of expression. We present here a new heat stress-inducible bidirectional promoter consisting of multimerized heat shock elements (HSE). The simplified architecture of this promoter largely improves the properties needed for an efficient induction system: dramatically reduced background activity, improved inducibility, and loss of all tissue specific components. Based on this new artificial promoter, we present a transient induction system for fish embryos. Application of this new induction system for Fgf8 misexpression during embryonic development reveals different windows of competence during eye development. A dramatic early phenotype resulting in loss of the eyes is observed for conventional mRNA injection. Later activation, by using our inducible promoter, uncovers different eye phenotypes like cyclopic eyes. Even after 14 days, an efficient heat stress response could be evoked in the injected embryos. The HSE promoter therefore represents a new artificial heat shock promoter with superior properties, making possible transient experiments with inducible misexpression at various stages of development.
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Affiliation(s)
- Baubak Bajoghli
- Institute of Animal Breeding and Genetics, University of Veterinary Medicine, Vienna, Austria
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44
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Carnicero E, Zelarayan LC, Rüttiger L, Knipper M, Alvarez Y, Alonso MT, Schimmang T. Differential roles of fibroblast growth factor-2 during development and maintenance of auditory sensory epithelia. J Neurosci Res 2004; 77:787-97. [PMID: 15334598 DOI: 10.1002/jnr.20222] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Fibroblast growth factor-2 (FGF2) has been postulated to be a key regulator involved in the proliferation, differentiation, and regeneration of sensory hair cells. Here we have addressed the potential functions of FGF2 during the formation and regeneration of the auditory epithelium in chicken and mice. By using viral gene transfer, based on herpes simplex type 1 virus (HSV-1), we show that ectopically applied FGF2 drastically increases the number of cells expressing early hair cell markers during embryonic development in avians. Intriguingly, FGF2 does not stimulate cell division during this process. These data suggest that FGF2 plays a role during differentiation of sensory hair cells in avians. To address the potential functions of FGF2 during murine inner ear development, we analyzed FGF2 mouse mutants. Mice lacking FGF2 showed normal formation of the inner ear, and no abnormalities were observed at the adult stage. Moreover, FGF2 mouse mutants showed similar hearing thresholds compared with those observed in control mice before and after noise damage. Therefore, endogenous FGF2 appears not to be essential for the development or functional maintenance of the auditory organ in mammals. In light of these results, the differential roles of FGF2 in the vertebrate inner ear are discussed with respect to its previously postulated functions.
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Affiliation(s)
- Estela Carnicero
- Center for Molecular Neurobiology Hamburg, University of Hamburg, Hamburg, Germany
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45
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Schlosser G, Ahrens K. Molecular anatomy of placode development in Xenopus laevis. Dev Biol 2004; 271:439-66. [PMID: 15223346 DOI: 10.1016/j.ydbio.2004.04.013] [Citation(s) in RCA: 181] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2004] [Revised: 04/15/2004] [Accepted: 04/16/2004] [Indexed: 11/18/2022]
Abstract
We analyzed the spatiotemporal pattern of expression of 15 transcription factors (Six1, Six4, Eya1, Sox3, Sox2, Pax6, Pax3, Pax2, Pax8, Dlx3, Msx1, FoxI1c, Tbx2, Tbx3, Xiro1) during placode development in Xenopus laevis from neural plate to late tail bud stages. Out of all genes investigated, only the expression of Eya1, Six1, and Six4 is maintained in all types of placode (except the lens) throughout embryonic development, suggesting that they may promote generic placodal properties and that their crescent-shaped expression domain surrounding the neural plate defines a panplacodal primordium from which all types of placode originate. Double-labeling procedures were employed to reveal the precise position of this panplacodal primordium relative to neural plate, neural crest, and other placodal markers. Already at neural plate stages, the panplacodal primordium is subdivided into several subregions defined by particular combinations of transcription factors allowing us to identify the approximate regions of origin of various types of placode. Whereas some types of placode were already prefigured by molecularly distinct areas at neural plate stages, the epibranchial, otic, and lateral line placodes arise from a common posterior placodal area (characterized by Pax8 and Pax2 expression) and acquire differential molecular signatures only after neural tube closure. Our findings argue for a multistep mechanism of placode induction, support a combinatorial model of placode specification, and suggest that different placodes evolved from a common placodal primordium by successive recruitment of new inducers and target genes.
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Affiliation(s)
- Gerhard Schlosser
- Brain Research Institute, University of Bremen, 28334 Bremen, Germany.
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46
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Alsina B, Abelló G, Ulloa E, Henrique D, Pujades C, Giraldez F. FGF signaling is required for determination of otic neuroblasts in the chick embryo. Dev Biol 2004; 267:119-34. [PMID: 14975721 DOI: 10.1016/j.ydbio.2003.11.012] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2003] [Revised: 10/01/2003] [Accepted: 11/10/2003] [Indexed: 10/26/2022]
Abstract
The interplay between intrinsic and extrinsic factors is essential for the transit into different cell states during development. We have analyzed the expression and function of FGF10 and FGF-signaling during the early stages of the development of otic neurons. FGF10 is expressed in a highly restricted domain overlapping the presumptive neurogenic region of the chick otic placode. A detailed study of the expression pattern of FGF10, proneural, and neurogenic genes revealed the following temporal sequence for the onset of gene expression: FGF10>Ngn1/Delta1/Hes5>NeuroD/NeuroM. FGF10 and FGF receptor inhibition cause opposed effects on cell determination and cell proliferation. Ectopic expression of FGF10 in vivo promotes an increase in NeuroD and NeuroM expression. BrdU incorporation experiments showed that the increase in NeuroD-expressing cells is not due to an increase in cell proliferation. Inhibition of FGF receptor signaling in otic explants causes a severe reduction in Neurogenin1, NeuroD, Delta1, and Hes5 expression with no change in non-neural genes like Lmx1. However, it does not interfere with NeuroD expression within the CVG or with neuroblast delamination. The loss of proneural gene expression caused by FGF inhibition is not caused by decreased cell proliferation or by increased cell death. We suggest that FGF signaling in the otic epithelium is required for neuronal precursors to withdraw from cell division and irreversibly commit to neuronal fate.
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Affiliation(s)
- Berta Alsina
- Biologia del Desenvolupament, Departament de Ciéncies Experimentals i de la Salut (DCEXS), Universitat Pompeu Fabra, 08003, Barcelona, Spain.
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Tateossian H, Powles N, Dickinson R, Ficker M, Maconochie M. Determination of downstream targets of FGF signalling using gene trap and cDNA subtractive approaches. Exp Cell Res 2004; 292:101-14. [PMID: 14720510 DOI: 10.1016/j.yexcr.2003.08.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Signalling through the fibroblast growth factor family (FGF) of ligands is essential for normal mammalian embryonic development. At a cellular level, many details of the molecular basis of the signal transduction process have been uncovered, but our knowledge of the identity of the downstream effectors of the FGF signal in the developing embryo remains limited. We have used two independent approaches to begin to identify downstream targets of FGF signalling in the embryo: (1). a gene trap approach and (2). cDNA subtraction, using mouse embryonic stem (ES) cells as a cellular system representative of an early window on the developing embryo. Both approaches led to the identification of a number of targets of FGF signalling, and we provide data to show that the chaperone Mrj, the tumour antigen Tum, collapsin mediator response protein Crmp, a novel transcriptional repressor Nac1 and ribophorin are all differentially regulated following FGF signalling. Independent gene trapping of Mrj previously indicated a role for the gene in embryogenesis [Development 126 (1999) 1247], and we present transcript data implicating a number of the newly isolated FGF target genes in different embryonic processes.
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Affiliation(s)
- Hilda Tateossian
- Mammalian Genetics Unit, Medical Research Council, Harwell, Oxon OX11 0RD, UK
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48
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Powles N, Marshall H, Economou A, Chiang C, Murakami A, Dickson C, Krumlauf R, Maconochie M. Regulatory analysis of the mouseFgf3 gene: Control of embryonic expression patterns and dependence upon sonic hedgehog (Shh) signalling. Dev Dyn 2004; 230:44-56. [PMID: 15108308 DOI: 10.1002/dvdy.20028] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Fgf3 displays a dynamic and complex expression pattern during mouse embryogenesis. To address the molecular mechanisms underlying Fgf3 expression, we used a transgenic approach to assay genomic regions from the mouse Fgf3 gene for regulatory activity. We identified an enhancer that mediates major components of embryonic expression, governing expression in the midbrain, hindbrain, surface ectoderm, dorsal roots and dorsal root ganglia (DRG), proximal sensory ganglia, and the developing central nervous system (CNS). Deletional analysis of the enhancer further delimited this regulatory activity to a 5.7-kb fragment. We have also revealed sonic hedgehog (Shh) -dependent and Shh-independent aspects of Fgf3 expression through breeding the Fgf3 reporter transgene into Shh mutants. In the absence of Shh signalling, Fgf3 reporter expression is lost in the ventral CNS, DRG, and superior cervical nerves, whereas activation of reporter expression in cranial ganglion cells is Shh independent. Moreover, detailed re-examination of the Shh phenotype revealed that Shh signalling is required for the correct development/maturation of the DRG.
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Affiliation(s)
- Nicola Powles
- Mammalian Genetics Unit, Medical Research Council, Harwell, Oxon, United Kingdom
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49
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Wright TJ, Hatch EP, Karabagli H, Karabagli P, Schoenwolf GC, Mansour SL. Expression of mouse fibroblast growth factor and fibroblast growth factor receptor genes during early inner ear development. Dev Dyn 2003; 228:267-72. [PMID: 14517998 DOI: 10.1002/dvdy.10362] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The inner ear, which mediates hearing and equilibrium, develops from an ectodermal placode located adjacent to the developing hindbrain. Induction of the placode and its subsequent morphogenesis and differentiation into the inner ear epithelium and its sensory neurons, involves signalling interactions within and between otic and non-otic tissues. Several members of the fibroblast growth factor (FGF) family play important roles at various stages of otic development; however, there are additional family members that have not been evaluated. In this study, we surveyed the expression patterns of 18 mouse Fgf and 3 Fgf receptor (Fgfr) genes during early otic development. Two members of the Fgf family, Fgf4 and Fgf16, and all three tested members of the Fgfr family, Fgfr2c, Fgfr3c, and Fgfr4, were expressed in tissues relevant to inner ear development. Fgf4 transcripts were expressed in the preplacodal and placodal ectoderm, suggesting potential roles in placode induction and/or maintenance. Fgf16 was expressed in the posterior otic cup and vesicle, suggesting roles in otic cell fate decisions and/or axis formation.
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Affiliation(s)
- Tracy J Wright
- Department of Human Genetics, University of Utah, Salt Lake City, Utah 84112-5330, USA
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50
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Abstract
The vertebrate inner ear is a marvel of structural and functional complexity, which is all the more remarkable because it develops from such a simple structure, the otic placode. Analysis of inner ear development has long been a fascination of experimental embryologists, who sought to understand cellular mechanisms of otic placode induction. More recently, however, molecular and genetic approaches have made the inner ear a useful model system for studying a much broader range of basic developmental mechanisms, including cell fate specification and differentiation, axial patterning, epithelial morphogenesis, cytoskeletal dynamics, stem cell biology, neurobiology, physiology, etc. Of course, there has also been tremendous progress in understanding the functions and processes peculiar to the inner ear. The goal of this review is to recount how historical approaches have shaped our understanding of the signaling interactions controlling early otic development; to discuss how new findings have led to fundamental new insights; and to point out new problems that need to be resolved in future research.
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Affiliation(s)
- Bruce B Riley
- Biology Department, Texas A&M University, College Station, TX 77843-3258, USA.
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