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Hidalgo-Sánchez M, Sánchez-Guardado L, Rodríguez-León J, Francisco-Morcillo J. The role of FGF15/FGF19 in the development of the central nervous system, eyes and inner ears in vertebrates. Tissue Cell 2024; 91:102619. [PMID: 39579736 DOI: 10.1016/j.tice.2024.102619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2024] [Revised: 11/11/2024] [Accepted: 11/12/2024] [Indexed: 11/25/2024]
Abstract
Fibroblast growth factor 19 (FGF19), and its rodent ortholog FGF15, is a member of a FGF subfamily directly involved in metabolism, acting in an endocrine way. During embryonic development, FGF15/FGF19 also functions as a paracrine or autocrine factor, regulating key events in a large number of organs. In this sense, the Fgf15/Fgf19 genes control the correct development of the brain, eye, inner ear, heart, pharyngeal pouches, tail bud and limbs, among other organs, as well as muscle growth in adulthood. These growth factors show relevant differences according to molecular structures, signalling pathway and function. Moreover, their expression patterns are highly dynamic at different stages of development, in particular in the central nervous system. The difficulty in understanding the action of these genes increases when comparing their expression patterns and regulatory mechanisms between different groups of vertebrates. The present review will address the expression patterns and functions of the Fgf15/Fgf19 genes at different stages of vertebrate embryonic development, with special attention to the regulation of the early specification, cell differentiation, and morphogenesis of the central nervous system and some sensory organs such as eye and inner ear. The most relevant anatomical aspects related to the structures analysed have also been considered in detail to provide an understandable context for the molecular and cellular studies shown.
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Affiliation(s)
- Matías Hidalgo-Sánchez
- Área de Biología Celular, Facultad de Ciencias, Universidad de Extremadura, Avda. de Elvas s/n, Badajoz 06071, Spain.
| | - Luis Sánchez-Guardado
- Área de Biología Celular, Facultad de Ciencias, Universidad de Extremadura, Avda. de Elvas s/n, Badajoz 06071, Spain
| | - Joaquín Rodríguez-León
- Área de Anatomía Humana, Facultad de Medicina y Ciencias de la Salud, Universidad de Extremadura, Avda. de Elvas s/n, Badajoz 06071, Spain
| | - Javier Francisco-Morcillo
- Área de Biología Celular, Facultad de Ciencias, Universidad de Extremadura, Avda. de Elvas s/n, Badajoz 06071, Spain
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2
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Liu X, Zhao Z, Shi X, Zong Y, Sun Y. The Effects of Viral Infections on the Molecular and Signaling Pathways Involved in the Development of the PAOs. Viruses 2024; 16:1342. [PMID: 39205316 PMCID: PMC11359136 DOI: 10.3390/v16081342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2024] [Revised: 08/06/2024] [Accepted: 08/20/2024] [Indexed: 09/04/2024] Open
Abstract
Cytomegalovirus infection contributes to 10-30% of congenital hearing loss in children. Vertebrate peripheral auditory organs include the outer, middle, and inner ear. Their development is regulated by multiple signaling pathways. However, most ear diseases due to viral infections are due to congenital infections and reactivation and affect healthy adults to a lesser extent. This may be due to the fact that viral infections affect signaling pathways that are important for the development of peripheral hearing organs. Therefore, an in-depth understanding of the relationship between viral infections and the signaling pathways involved in the development of peripheral hearing organs is important for the prevention and treatment of ear diseases. In this review, we summarize the effects of viruses on signaling pathways and signaling molecules in the development of peripheral auditory organs.
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Affiliation(s)
- Xiaozhou Liu
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Zhengdong Zhao
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Xinyu Shi
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Yanjun Zong
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Yu Sun
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
- Hubei Province Key Laboratory of Oral and Maxillofacial Development and Regeneration, Wuhan 430022, China
- Institute of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
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3
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Żak M, Støle TP, Plagnol V, Daudet N. Regulation of otic neurosensory specification by Notch and Wnt signalling: insights from RNA-seq screenings in the embryonic chicken inner ear. Front Cell Dev Biol 2023; 11:1245330. [PMID: 37900277 PMCID: PMC10600479 DOI: 10.3389/fcell.2023.1245330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Accepted: 09/25/2023] [Indexed: 10/31/2023] Open
Abstract
The Notch and Wnt signalling pathways play key roles in the formation of inner ear sensory organs, but little is known about their transcriptional effectors and targets in this context. Here, we perturbed Notch and Wnt activities in the embryonic chicken otic vesicle using pharmacological treatment or in ovo electroporation of plasmid DNA, and used RNA-Seq to analyse the resulting changes in gene expression. Compared to pharmacological treatments, in ovo electroporation changed the expression of fewer genes, a likely consequence of the variability and mosaicism of transfection. The pharmacological inhibition of Notch activity induced a rapid change in the expression of known effectors of this pathway and genes associated with neurogenesis, consistent with a switch towards an otic neurosensory fate. The Wnt datasets contained many genes associated with a neurosensory biological function, confirming the importance of this pathway for neurosensory specification in the otocyst. Finally, the results of a preliminary gain-of-function screening of selected transcription factors and Wnt signalling components suggest that the endogenous programs of otic neurosensory specification are very robust, and in general unaffected by the overexpression of a single factor. Altogether this work provides new insights into the effectors and candidate targets of the Notch and Wnt pathways in the early developing inner ear and could serve as a useful reference for future functional genomics experiments in the embryonic avian inner ear.
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Affiliation(s)
- Magdalena Żak
- UCL Ear Institute, University College London, London, United Kingdom
| | - Thea P. Støle
- UCL Ear Institute, University College London, London, United Kingdom
| | - Vincent Plagnol
- Genetics Institute, University College London, London, United Kingdom
| | - Nicolas Daudet
- UCL Ear Institute, University College London, London, United Kingdom
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4
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Sohel MSH, Atoji Y, Onouchi S, Saito S. Expression patterns of prosaposin and neurotransmitter-related molecules in the chick paratympanic organ. Tissue Cell 2023; 83:102130. [PMID: 37320868 DOI: 10.1016/j.tice.2023.102130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 06/01/2023] [Accepted: 06/08/2023] [Indexed: 06/17/2023]
Abstract
The paratympanic organ (PTO) is a small sense organ in the middle ear of birds that contains hair cells similar to those found in vestibuloauditory organs and receives afferent fibers from the geniculate ganglion. To consider the histochemical similarities between the PTO and vestibular hair cells, we examined the expression patterns of representative molecules in vestibular hair cells, including prosaposin, G protein-coupled receptor (GPR) 37 and GPR37L1 as prosaposin receptors, vesicular glutamate transporter (vGluT) 2 and vGluT3, nicotinic acetylcholine receptor subunit α9 (nAChRα9), and glutamic acid decarboxylase (GAD) 65 and GAD67, in the postnatal day 0 chick PTO and geniculate ganglion by in situ hybridization. Prosaposin mRNA was observed in PTO hair cells, supporting cells, and geniculate ganglion cells. vGluT3 mRNA was observed in PTO hair cells, whereas vGluT2 was observed in a small number of ganglion cells. nAChRα9 mRNA was observed in a small number of PTO hair cells. The results suggest that the histochemical character of PTO hair cells is more similar to that of vestibular hair cells than that of auditory hair cells in chicks.
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Affiliation(s)
- Md Shahriar Hasan Sohel
- Laboratory of Veterinary Anatomy, Joint Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Yasuro Atoji
- Laboratory of Veterinary Anatomy, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Sawa Onouchi
- Laboratory of Veterinary Anatomy, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan
| | - Shouichiro Saito
- Laboratory of Veterinary Anatomy, Joint Graduate School of Veterinary Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan; Laboratory of Veterinary Anatomy, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.
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5
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Origin of Neuroblasts in the Avian Otic Placode and Their Distributions in the Acoustic and Vestibular Ganglia. BIOLOGY 2023; 12:biology12030453. [PMID: 36979145 PMCID: PMC10045822 DOI: 10.3390/biology12030453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 03/09/2023] [Accepted: 03/13/2023] [Indexed: 03/18/2023]
Abstract
The inner ear is a complex three-dimensional sensorial structure with auditory and vestibular functions. This intricate sensory organ originates from the otic placode, which generates the sensory elements of the membranous labyrinth, as well as all the ganglionic neuronal precursors. How auditory and vestibular neurons establish their fate identities remains to be determined. Their topological origin in the incipient otic placode could provide positional information before they migrate, to later segregate in specific portions of the acoustic and vestibular ganglia. To address this question, transplants of small portions of the avian otic placode were performed according to our previous fate map study, using the quail/chick chimeric graft model. All grafts taking small areas of the neurogenic placodal domain contributed neuroblasts to both acoustic and vestibular ganglia. A differential distribution of otic neurons in the anterior and posterior lobes of the vestibular ganglion, as well as in the proximal, intermediate, and distal portions of the acoustic ganglion, was found. Our results clearly show that, in birds, there does not seem to be a strict segregation of acoustic and vestibular neurons in the incipient otic placode.
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Nomdedeu-Sancho G, Alsina B. Wiring the senses: Factors that regulate peripheral axon pathfinding in sensory systems. Dev Dyn 2023; 252:81-103. [PMID: 35972036 PMCID: PMC10087148 DOI: 10.1002/dvdy.523] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 08/09/2022] [Accepted: 08/12/2022] [Indexed: 01/04/2023] Open
Abstract
Sensory neurons of the head are the ones that transmit the information about the external world to our brain for its processing. Axons from cranial sensory neurons sense different chemoattractant and chemorepulsive molecules during the journey and in the target tissue to establish the precise innervation with brain neurons and/or receptor cells. Here, we aim to unify and summarize the available information regarding molecular mechanisms guiding the different afferent sensory axons of the head. By putting the information together, we find the use of similar guidance cues in different sensory systems but in distinct combinations. In vertebrates, the number of genes in each family of guidance cues has suffered a great expansion in the genome, providing redundancy, and robustness. We also discuss recently published data involving the role of glia and mechanical forces in shaping the axon paths. Finally, we highlight the remaining questions to be addressed in the field.
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Affiliation(s)
- Gemma Nomdedeu-Sancho
- Department of Medicine and Life Sciences, Universitat Pompeu Fabra, Parc de Recerca Biomèdica de Barcelona, Barcelona, Spain
| | - Berta Alsina
- Department of Medicine and Life Sciences, Universitat Pompeu Fabra, Parc de Recerca Biomèdica de Barcelona, Barcelona, Spain
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7
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Mackowetzky K, Dicipulo R, Fox SC, Philibert DA, Todesco H, Doshi JD, Kawakami K, Tierney K, Waskiewicz AJ. Retinoic acid signaling regulates late stages of semicircular canal morphogenesis and otolith maintenance in the zebrafish inner ear. Dev Dyn 2022; 251:1798-1815. [PMID: 35710880 DOI: 10.1002/dvdy.510] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 03/09/2022] [Accepted: 03/10/2022] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND The vitamin A derivative all-trans retinoic acid (RA) regulates early stages of inner ear development. As the early disruption of the RA pathway results in profound mispatterning of the developing inner ear, this confounds analyses of specific roles in later stages. Therefore, we used the temporal-specific exposure of all-trans RA or diethylaminobenzaldehyde to evaluate RA functions in late otic development. RESULTS Perturbing late RA signaling causes behavioral defects analogous to those expected in larvae suffering from vestibular dysfunction. These larvae also demonstrate malformations of the semi-circular canals, as visualized through (a) use of the transgenic strain nkhspdmc12a, a fluorescent reporter expressed in otic epithelium; and (b) injection of the fluorescent lipophilic dye DiI. We also noted the altered expression of genes encoding ECM proteins or modifying enzymes. Other malformations of the inner ear observed in our work include the loss or reduced size of the utricular and saccular otoliths, suggesting a role for RA in otolith maintenance. CONCLUSION Our work has identified a previously undescribed late phase of RA activity in otic development, demonstrating that vestibular defects observed in human patients in relation to perturbed RA signaling are not solely due to its early disruption in otic development.
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Affiliation(s)
- Kacey Mackowetzky
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Renée Dicipulo
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Sabrina C Fox
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.,Women & Children's Health Research Institute, Edmonton, Alberta, Canada
| | - Danielle A Philibert
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Hayley Todesco
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Jainil D Doshi
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Koichi Kawakami
- Laboratory of Molecular and Developmental Biology, National Institute of Genetics, Shizuoka, Japan
| | - Keith Tierney
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.,School of Public Health, University of Alberta, Edmonton, Alberta, Canada
| | - Andrew J Waskiewicz
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.,Women & Children's Health Research Institute, Edmonton, Alberta, Canada
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8
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Single-cell transcriptomic landscapes of the otic neuronal lineage at multiple early embryonic ages. Cell Rep 2022; 38:110542. [PMID: 35320729 DOI: 10.1016/j.celrep.2022.110542] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 12/03/2021] [Accepted: 02/25/2022] [Indexed: 11/20/2022] Open
Abstract
Inner ear vestibular and spiral ganglion neurons (VGNs and SGNs) are known to play pivotal roles in balance control and sound detection. However, the molecular mechanisms underlying otic neurogenesis at early embryonic ages have remained unclear. Here, we use single-cell RNA sequencing to reveal the transcriptomes of mouse otic tissues at three embryonic ages, embryonic day 9.5 (E9.5), E11.5, and E13.5, covering proliferating and undifferentiated otic neuroblasts and differentiating VGNs and SGNs. We validate the high quality of our studies by using multiple assays, including genetic fate mapping analysis, and we uncover several genes upregulated in neuroblasts or differentiating VGNs and SGNs, such as Shox2, Myt1, Casz1, and Sall3. Notably, our findings suggest a general cascaded differentiation trajectory during early otic neurogenesis. The comprehensive understanding of early otic neurogenesis provided by our study holds critical implications for both basic and translational research.
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9
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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: 8] [Impact Index Per Article: 2.0] [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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10
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Almasoudi SH, Schlosser G. Otic Neurogenesis in Xenopus laevis: Proliferation, Differentiation, and the Role of Eya1. Front Neuroanat 2021; 15:722374. [PMID: 34616280 PMCID: PMC8488300 DOI: 10.3389/fnana.2021.722374] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 08/27/2021] [Indexed: 11/15/2022] Open
Abstract
Using immunostaining and confocal microscopy, we here provide the first detailed description of otic neurogenesis in Xenopus laevis. We show that the otic vesicle comprises a pseudostratified epithelium with apicobasal polarity (apical enrichment of Par3, aPKC, phosphorylated Myosin light chain, N-cadherin) and interkinetic nuclear migration (apical localization of mitotic, pH3-positive cells). A Sox3-immunopositive neurosensory area in the ventromedial otic vesicle gives rise to neuroblasts, which delaminate through breaches in the basal lamina between stages 26/27 and 39. Delaminated cells congregate to form the vestibulocochlear ganglion, whose peripheral cells continue to proliferate (as judged by EdU incorporation), while central cells differentiate into Islet1/2-immunopositive neurons from stage 29 on and send out neurites at stage 31. The central part of the neurosensory area retains Sox3 but stops proliferating from stage 33, forming the first sensory areas (utricular/saccular maculae). The phosphatase and transcriptional coactivator Eya1 has previously been shown to play a central role for otic neurogenesis but the underlying mechanism is poorly understood. Using an antibody specifically raised against Xenopus Eya1, we characterize the subcellular localization of Eya1 proteins, their levels of expression as well as their distribution in relation to progenitor and neuronal differentiation markers during otic neurogenesis. We show that Eya1 protein localizes to both nuclei and cytoplasm in the otic epithelium, with levels of nuclear Eya1 declining in differentiating (Islet1/2+) vestibulocochlear ganglion neurons and in the developing sensory areas. Morpholino-based knockdown of Eya1 leads to reduction of proliferating, Sox3- and Islet1/2-immunopositive cells, redistribution of cell polarity proteins and loss of N-cadherin suggesting that Eya1 is required for maintenance of epithelial cells with apicobasal polarity, progenitor proliferation and neuronal differentiation during otic neurogenesis.
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Affiliation(s)
| | - Gerhard Schlosser
- School of Natural Sciences, National University of Galway, Galway, Ireland
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11
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Żak M, Daudet N. A gradient of Wnt activity positions the neurosensory domains of the inner ear. eLife 2021; 10:59540. [PMID: 33704062 PMCID: PMC7993990 DOI: 10.7554/elife.59540] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 03/09/2021] [Indexed: 12/25/2022] Open
Abstract
The auditory and vestibular organs of the inner ear and the neurons that innervate them originate from Sox2-positive and Notch-active neurosensory domains specified at early stages of otic development. Sox2 is initially present throughout the otic placode and otocyst, and then it becomes progressively restricted to a ventro-medial domain. Using gain- and loss-of-function approaches in the chicken otocyst, we show that these early changes in Sox2 expression are regulated in a dose-dependent manner by Wnt/beta-catenin signalling. Both high and very low levels of Wnt activity repress Sox2 and neurosensory competence. However, intermediate levels allow the maintenance of Sox2 expression and sensory organ formation. We propose that a dorso-ventral (high-to-low) gradient and wave of Wnt activity initiated at the dorsal rim of the otic placode progressively restricts Sox2 and Notch activity to the ventral half of the otocyst, thereby positioning the neurosensory competent domains in the inner ear.
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Affiliation(s)
- Magdalena Żak
- UCL Ear Institute, University College London, London, United Kingdom
| | - Nicolas Daudet
- UCL Ear Institute, University College London, London, United Kingdom
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12
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Sánchez-Guardado LÓ, Puelles L, Hidalgo-Sánchez M. Origin of acoustic-vestibular ganglionic neuroblasts in chick embryos and their sensory connections. Brain Struct Funct 2019; 224:2757-2774. [PMID: 31396696 DOI: 10.1007/s00429-019-01934-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Accepted: 07/31/2019] [Indexed: 01/03/2023]
Abstract
The inner ear is a complex three-dimensional sensory structure with auditory and vestibular functions. It originates from the otic placode, which generates the sensory elements of the membranous labyrinth and all the ganglionic neuronal precursors. Neuroblast specification is the first cell differentiation event. In the chick, it takes place over a long embryonic period from the early otic cup stage to at least stage HH25. The differentiating ganglionic neurons attain a precise innervation pattern with sensory patches, a process presumably governed by a network of dendritic guidance cues which vary with the local micro-environment. To study the otic neurogenesis and topographically-ordered innervation pattern in birds, a quail-chick chimaeric graft technique was used in accordance with a previously determined fate-map of the otic placode. Each type of graft containing the presumptive domain of topologically-arranged placodal sensory areas was shown to generate neuroblasts. The differentiated grafted neuroblasts established dendritic contacts with a variety of sensory patches. These results strongly suggest that, rather than reverse-pathfinding, the relevant role in otic dendritic process guidance is played by long-range diffusing molecules.
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Affiliation(s)
| | - Luis Puelles
- Department of Human Anatomy and Psychobiology, School of Medicine, University of Murcia, E30100, Murcia, Spain.,Instituto Murciano de Investigaciones Biosanitarias (IMIB-Arrixaca), E30100, Murcia, Spain
| | - Matías Hidalgo-Sánchez
- Department of Cell Biology, School of Science, University of Extremadura, E06071, Badajoz, Spain.
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13
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Duncan JS, Fritzsch B, Houston DW, Ketchum EM, Kersigo J, Deans MR, Elliott KL. Topologically correct central projections of tetrapod inner ear afferents require Fzd3. Sci Rep 2019; 9:10298. [PMID: 31311957 PMCID: PMC6635624 DOI: 10.1038/s41598-019-46553-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 06/29/2019] [Indexed: 12/27/2022] Open
Abstract
Inner ear sensory afferent connections establish sensory maps between the inner ear hair cells and the vestibular and auditory nuclei to allow vestibular and sound information processing. While molecular guidance of sensory afferents to the periphery has been well studied, molecular guidance of central projections from the ear is only beginning to emerge. Disorganized central projections of spiral ganglion neurons in a Wnt/PCP pathway mutant, Prickle1, suggest the Wnt/PCP pathway plays a role in guiding cochlear afferents to the cochlear nuclei in the hindbrain, consistent with known expression of the Wnt receptor, Frizzled3 (Fzd3) in inner ear neurons. We therefore investigated the role of Wnt signaling in central pathfinding in Fzd3 mutant mice and Fzd3 morpholino treated frogs and found aberrant central projections of vestibular afferents in both cases. Ear transplantations from knockdown to control Xenopus showed that it is the Fzd3 expressed within the ear that mediates this guidance. Also, cochlear afferents of Fzd3 mutant mice lack the orderly topological organization observed in controls. Quantification of Fzd3 expression in spiral ganglion neurons show a gradient of expression with Fzd3 being higher in the apex than in the base. Together, these results suggest that a gradient of Fzd3 in inner ear afferents directs projections to the correct dorsoventral column within the hindbrain.
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Affiliation(s)
- Jeremy S Duncan
- Department of Biological Sciences, Western Michigan University, Kalamazoo, MI, USA
| | - Bernd Fritzsch
- Department of Biology, University of Iowa, Iowa City, IA, USA
| | | | - Elizabeth M Ketchum
- Department of Biological Sciences, Western Michigan University, Kalamazoo, MI, USA
| | | | - Michael R Deans
- Department of Surgery, Division of Otolaryngology, and Department of Neurobiology & Anatomy, University of Utah School of Medicine, Salt Lake City, UT, USA
| | - Karen L Elliott
- Department of Biology, University of Iowa, Iowa City, IA, USA.
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14
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Schlosser G. A Short History of Nearly Every Sense-The Evolutionary History of Vertebrate Sensory Cell Types. Integr Comp Biol 2019; 58:301-316. [PMID: 29741623 DOI: 10.1093/icb/icy024] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Evolving from filter feeding chordate ancestors, vertebrates adopted a more active life style. These ecological and behavioral changes went along with an elaboration of the vertebrate head including novel complex paired sense organs such as the eyes, inner ears, and olfactory epithelia. However, the photoreceptors, mechanoreceptors, and chemoreceptors used in these sense organs have a long evolutionary history and homologous cell types can be recognized in many other bilaterians or even cnidarians. After briefly introducing some of the major sensory cell types found in vertebrates, this review summarizes the phylogenetic distribution of sensory cell types in metazoans and presents a scenario for the evolutionary history of various sensory cell types involving several cell type diversification and fusion events. It is proposed that the evolution of novel cranial sense organs in vertebrates involved the redeployment of evolutionarily ancient sensory cell types for building larger and more complex sense organs.
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Affiliation(s)
- Gerhard Schlosser
- School of Natural Sciences and Regenerative Medicine Institute (REMEDI), National University of Ireland, Biomedical Sciences Building, Newcastle Road, Galway H91 TK33, Ireland
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15
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Abstract
Neurons of the cochleovestibular ganglion (CVG) transmit hearing and balance information to the brain. During development, a select population of early otic progenitors express NEUROG1, delaminate from the otocyst, and coalesce to form the neurons that innervate all inner ear sensory regions. At present, the selection process that determines which otic progenitors activate NEUROG1 and adopt a neuroblast fate is incompletely understood. The transcription factor SOX2 has been implicated in otic neurogenesis, but its requirement in the specification of the CVG neurons has not been established. Here we tested SOX2's requirement during inner ear neuronal specification using a conditional deletion paradigm in the mouse. SOX2 deficiency at otocyst stages caused a near-absence of NEUROG1-expressing neuroblasts, increased cell death in the neurosensory epithelium, and significantly reduced the CVG volume. Interestingly, a milder decrease in neurogenesis was observed in heterozygotes, indicating SOX2 levels are important. Moreover, fate-mapping experiments revealed that the timing of SOX2 expression did not parallel the established vestibular-then-auditory sequence. These results demonstrate that SOX2 is required for the initial events in otic neuronal specification including expression of NEUROG1, although fate-mapping results suggest SOX2 may be required as a competence factor rather than a direct initiator of the neural fate.
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Affiliation(s)
- Aleta R Steevens
- Flaum Eye Institute, University of Rochester Medical Center, Rochester, NY, USA
| | | | - Jenna C Glatzer
- Flaum Eye Institute, University of Rochester Medical Center, Rochester, NY, USA
| | - Amy E Kiernan
- Flaum Eye Institute, University of Rochester Medical Center, Rochester, NY, USA. .,Department of Biomedical Genetics, University of Rochester Medical Center, Rochester, NY, USA.
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16
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Xu J, Ueno H, Xu CY, Chen B, Weissman IL, Xu PX. Identification of mouse cochlear progenitors that develop hair and supporting cells in the organ of Corti. Nat Commun 2017; 8:15046. [PMID: 28492243 PMCID: PMC5437288 DOI: 10.1038/ncomms15046] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 02/23/2017] [Indexed: 01/20/2023] Open
Abstract
The adult mammalian cochlear sensory epithelium houses two major types of cells, mechanosensory hair cells and underlying supporting cells, and lacks regenerative capacity. Recent evidence indicates that a subset of supporting cells can spontaneously regenerate hair cells after ablation only within the first week postparturition. Here in vivo clonal analysis of mouse inner ear cells during development demonstrates clonal relationship between hair and supporting cells in sensory organs. We report the identification in mouse of a previously unknown population of multipotent stem/progenitor cells that are capable of not only contributing to the hair and supporting cells but also to other cell types, including glia, in cochlea undergoing development, maturation and repair in response to damage. These multipotent progenitors originate from Eya1-expressing otic progenitors. Our findings also provide evidence for detectable regenerative potential in the postnatal cochlea beyond 1 week of age.
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Affiliation(s)
- Jinshu Xu
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Hiroo Ueno
- Institute of Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, California 94305, USA
- Ludwig Center, Stanford University, Stanford, California 94305, USA
- Department of Pathology, Stanford University, Stanford, California 94305, USA
| | - Chelsea Y. Xu
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Binglai Chen
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Irving L. Weissman
- Institute of Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, California 94305, USA
- Ludwig Center, Stanford University, Stanford, California 94305, USA
- Department of Pathology, Stanford University, Stanford, California 94305, USA
| | - Pin-Xian Xu
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
- Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
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17
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Sculpting the labyrinth: Morphogenesis of the developing inner ear. Semin Cell Dev Biol 2017; 65:47-59. [DOI: 10.1016/j.semcdb.2016.09.015] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 07/26/2016] [Accepted: 09/25/2016] [Indexed: 01/23/2023]
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18
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Gálvez H, Abelló G, Giraldez F. Signaling and Transcription Factors during Inner Ear Development: The Generation of Hair Cells and Otic Neurons. Front Cell Dev Biol 2017; 5:21. [PMID: 28393066 PMCID: PMC5364141 DOI: 10.3389/fcell.2017.00021] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Accepted: 03/02/2017] [Indexed: 12/21/2022] Open
Abstract
Integration between cell signals and bHLH transcription factors plays a prominent role during the development of hair cells of the inner ear. Hair cells are the sensory receptors of the inner ear, responsible for the mechano-transduction of sound waves into electrical signals. They derive from multipotent progenitors that reside in the otic placode. Progenitor commitment is the result of cell signaling from the surrounding tissues that result in the restricted expression of SoxB1 transcription factors, Sox2 and Sox3. In turn, they induce the expression of Neurog1 and Atoh1, two bHLH factors that specify neuronal and hair cell fates, respectively. Neuronal and hair cell development, however, do not occur simultaneously. Hair cell development is prevented during neurogenesis and prosensory stages, resulting in the delay of hair cell development with respect to neuron production. Negative interactions between Neurog1 and Atoh1, and of Atoh1 with other bHLH factors driven by Notch signaling, like Hey1 and Hes5, account for this delay. In summary, the regulation of Atoh1 and hair cell development relies on interactions between cell signaling and bHLH transcription factors that dictate cell fate and timing decisions during development. Interestingly, these mechanisms operate as well during hair cell regeneration after damage and during stem cell directed differentiation, making developmental studies instrumental for improving therapies for hearing impairment.
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Affiliation(s)
- Héctor Gálvez
- Developmental Biology, CEXS, Parc de Recerca Biomèdica de Barcelona, Universitat Pompeu Fabra Barcelona, Spain
| | - Gina Abelló
- Developmental Biology, CEXS, Parc de Recerca Biomèdica de Barcelona, Universitat Pompeu Fabra Barcelona, Spain
| | - Fernando Giraldez
- Developmental Biology, CEXS, Parc de Recerca Biomèdica de Barcelona, Universitat Pompeu Fabra Barcelona, Spain
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19
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Dyballa S, Savy T, Germann P, Mikula K, Remesikova M, Špir R, Zecca A, Peyriéras N, Pujades C. Distribution of neurosensory progenitor pools during inner ear morphogenesis unveiled by cell lineage reconstruction. eLife 2017; 6:22268. [PMID: 28051766 PMCID: PMC5243114 DOI: 10.7554/elife.22268] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 12/23/2016] [Indexed: 01/01/2023] Open
Abstract
Reconstructing the lineage of cells is central to understanding how the wide diversity of cell types develops. Here, we provide the neurosensory lineage reconstruction of a complex sensory organ, the inner ear, by imaging zebrafish embryos in vivo over an extended timespan, combining cell tracing and cell fate marker expression over time. We deliver the first dynamic map of early neuronal and sensory progenitor pools in the whole otic vesicle. It highlights the remodeling of the neuronal progenitor domain upon neuroblast delamination, and reveals that the order and place of neuroblasts' delamination from the otic epithelium prefigure their position within the SAG. Sensory and non-sensory domains harbor different proliferative activity contributing distinctly to the overall growth of the structure. Therefore, the otic vesicle case exemplifies a generic morphogenetic process where spatial and temporal cues regulate cell fate and functional organization of the rudiment of the definitive organ.
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Affiliation(s)
- Sylvia Dyballa
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Thierry Savy
- Multilevel Dynamics in Morphogenesis Unit, USR3695 CNRS, Gif sur Yvette, France
| | - Philipp Germann
- Systems Biology Unit, Center for Genomic Regulation, Barcelona, Spain
| | - Karol Mikula
- Department of Mathematics, Slovak University of Technology, Bratislava, Slovakia
| | - Mariana Remesikova
- Department of Mathematics, Slovak University of Technology, Bratislava, Slovakia
| | - Róbert Špir
- Department of Mathematics, Slovak University of Technology, Bratislava, Slovakia
| | - Andrea Zecca
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain
| | - Nadine Peyriéras
- Multilevel Dynamics in Morphogenesis Unit, USR3695 CNRS, Gif sur Yvette, France
| | - Cristina Pujades
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain
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20
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Abstract
Cell types are the basic building blocks of multicellular organisms and are extensively diversified in animals. Despite recent advances in characterizing cell types, classification schemes remain ambiguous. We propose an evolutionary definition of a cell type that allows cell types to be delineated and compared within and between species. Key to cell type identity are evolutionary changes in the 'core regulatory complex' (CoRC) of transcription factors, that make emergent sister cell types distinct, enable their independent evolution and regulate cell type-specific traits termed apomeres. We discuss the distinction between developmental and evolutionary lineages, and present a roadmap for future research.
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21
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Deng X, Wu DK. Temporal coupling between specifications of neuronal and macular fates of the inner ear. Dev Biol 2016; 414:21-33. [PMID: 27083418 DOI: 10.1016/j.ydbio.2016.04.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 04/08/2016] [Accepted: 04/11/2016] [Indexed: 12/21/2022]
Abstract
The inner ear is a complex organ comprised of various specialized sensory organs for detecting sound and head movements. The timing of specification for these sensory organs, however, is not clear. Previous fate mapping results of the inner ear indicate that vestibular and auditory ganglia and two of the vestibular sensory organs, the utricular macula (UM) and saccular macula (SM), are lineage related. Based on the medial-lateral relationship where respective auditory and vestibular neuroblasts exit from the otic epithelium and the subsequent formation of the medial SM and lateral UM in these regions, we hypothesized that specification of the two lateral structures, the vestibular ganglion and the UM are coupled and likewise for the two medial structures, the auditory ganglion and the SM. We tested this hypothesis by surgically inverting the primary axes of the otic cup in ovo and investigating the fate of the vestibular neurogenic region, which had been spotted with a lipophilic dye. Our results showed that the laterally-positioned, dye-associated, vestibular ganglion and UM were largely normal in transplanted ears, whereas both auditory ganglion and SM showed abnormalities suggesting the lateral but not the medial-derived structures were mostly specified at the time of transplantation. Both of these results are consistent with a temporal coupling between neuronal and macular fate specifications.
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Affiliation(s)
- Xiaohong Deng
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, United States
| | - Doris K Wu
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, United States.
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22
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Evsen L, Doetzlhofer A. Gene Transfer into the Chicken Auditory Organ by In Ovo Micro-electroporation. J Vis Exp 2016. [PMID: 27167684 DOI: 10.3791/53864] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Chicken embryos are ideal model systems for studying embryonic development as manipulations of gene function can be conducted with relative ease in ovo. The inner ear auditory sensory organ is critical for our ability to hear. It houses a highly specialized sensory epithelium that consists of mechano-transducing hair cells (HCs) and surrounding glial-like supporting cells (SCs). Despite structural differences in the auditory organs, molecular mechanisms regulating the development of the auditory organ are evolutionarily conserved between mammals and aves. In ovo electroporation is largely limited to early stages at E1 - E3. Due to the relative late development of the auditory organ at E5, manipulations of the auditory organ by in ovo electroporation past E3 are difficult due to the advanced development of the chicken embryo at later stages. The method presented here is a transient gene transfer method for targeting genes of interest at stage E4 - E4.5 in the developing chicken auditory sensory organ via in ovo micro-electroporation. This method is applicable for gain- and loss-of-functions with conventional plasmid DNA-based expression vectors and can be combined with in ovo cell proliferation assay by adding EdU (5-ethynyl-2´-deoxyuridine) to the whole embryo at the time of electroporation. The use of green or red fluorescent protein (GFP or RFP) expression plasmids allows the experimenter to quickly determine whether the electroporation successfully targeted the auditory portion of the developing inner ear. In this method paper, representative examples of GFP electroporated specimens are illustrated; embryos were harvested 18 - 96 hr after electroporation and targeting of GFP to the pro-sensory area of the auditory organ was confirmed by RNA in situ hybridization. The method paper also provides an optimized protocol for the use of the thymidine analog EdU to analyze cell proliferation; an example of an EdU based cell proliferation assay that combines immuno-labeling and click EdU chemistry is provided.
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Affiliation(s)
- Lale Evsen
- The Solomon H. Snyder Department of Neuroscience, The Center for Sensory Biology, The Johns Hopkins University, School of Medicine
| | - Angelika Doetzlhofer
- The Solomon H. Snyder Department of Neuroscience, The Center for Sensory Biology, The Johns Hopkins University, School of Medicine;
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23
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Azadeh J, Song Z, Laureano AS, Toro-Ramos A, Kwan K. Initiating Differentiation in Immortalized Multipotent Otic Progenitor Cells. J Vis Exp 2016. [PMID: 26780605 DOI: 10.3791/53692] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Use of human induced pluripotent stem cells (iPSC) or embryonic stem cells (ESC) for cell replacement therapies holds great promise. Several limitations including low yields and heterogeneous populations of differentiated cells hinder the progress of stem cell therapies. A fate restricted immortalized multipotent otic progenitor (iMOP) cell line was generated to facilitate efficient differentiation of large numbers of functional hair cells and spiral ganglion neurons (SGN) for inner ear cell replacement therapies. Starting from dissociated cultures of single iMOP cells, protocols that promote cell cycle exit and differentiation by basic fibroblast growth factor (bFGF) withdrawal were described. A significant decrease in proliferating cells after bFGF withdrawal was confirmed using an EdU cell proliferation assay. Concomitant with a decrease in proliferation, successful differentiation resulted in expression of molecular markers and morphological changes. Immunostaining of Cdkn1b (p27(KIP)) and Cdh1 (E-cadherin) in iMOP-derived otospheres was used as an indicator for differentiation into inner ear sensory epithelia while immunostaining of Cdkn1b and Tubb3 (neuronal β-tubulin) was used to identify iMOP-derived neurons. Use of iMOP cells provides an important tool for understanding cell fate decisions made by inner ear neurosensory progenitors and will help develop protocols for generating large numbers of iPSC or ESC-derived hair cells and SGNs. These methods will accelerate efforts for generating otic cells for replacement therapies.
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Affiliation(s)
| | | | | | | | - Kelvin Kwan
- Cell Biology & Neuroscience, Rutgers University;
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24
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Goodrich LV. Early Development of the Spiral Ganglion. THE PRIMARY AUDITORY NEURONS OF THE MAMMALIAN COCHLEA 2016. [DOI: 10.1007/978-1-4939-3031-9_2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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25
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Nakajima Y. Signaling regulating inner ear development: cell fate determination, patterning, morphogenesis, and defects. Congenit Anom (Kyoto) 2015; 55:17-25. [PMID: 25040109 DOI: 10.1111/cga.12072] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2014] [Accepted: 06/07/2014] [Indexed: 12/28/2022]
Abstract
The membranous labyrinth of the inner ear is a highly complex organ that detects sound and balance. Developmental defects in the inner ear cause congenital hearing loss and balance disorders. The membranous labyrinth consists of three semicircular ducts, the utricle, saccule, and endolymphatic ducts, and the cochlear duct. These complex structures develop from the simple otic placode, which is established in the cranial ectoderm adjacent to the neural crest at the level of the hindbrain at the early neurula stage. During development, the otic placode invaginates to form the otic vesicle, which subsequently gives rise to neurons for the vestibulocochlear ganglion, the non-sensory and sensory epithelia of the membranous labyrinth that includes three ampullary crests, two maculae, and the organ of Corti. Combined paracrine and autocrine signals including fibroblast growth factor, Wnt, retinoic acid, hedgehog, and bone morphogenetic protein regulate fate determination, axis formation, and morphogenesis in the developing inner ear. Juxtacrine signals mediated by Notch pathways play a role in establishing the sensory epithelium, which consists of mechanosensory hair cells and supporting cells. The highly differentiated organ of Corti, which consists of uniformly oriented inner/outer hair cells and specific supporting cells, develops during fetal development. Developmental alterations/arrest causes congenital malformations in the inner ear in a spatiotemporal-restricted manner. A clearer understanding of the mechanisms underlying inner ear development is important not only for the management of patients with congenital inner ear malformations, but also for the development of regenerative therapy for impaired function.
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Affiliation(s)
- Yuji Nakajima
- Department of Anatomy and Cell Biology, Graduate School of Medicine, Osaka City University, Osaka, Japan
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26
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Schlosser G. Vertebrate cranial placodes as evolutionary innovations--the ancestor's tale. Curr Top Dev Biol 2015; 111:235-300. [PMID: 25662263 DOI: 10.1016/bs.ctdb.2014.11.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Evolutionary innovations often arise by tinkering with preexisting components building new regulatory networks by the rewiring of old parts. The cranial placodes of vertebrates, ectodermal thickenings that give rise to many of the cranial sense organs (ear, nose, lateral line) and ganglia, originated as such novel structures, when vertebrate ancestors elaborated their head in support of a more active and exploratory life style. This review addresses the question of how cranial placodes evolved by tinkering with ectodermal patterning mechanisms and sensory and neurosecretory cell types that have their own evolutionary history. With phylogenetic relationships among the major branches of metazoans now relatively well established, a comparative approach is used to infer, which structures evolved in which lineages and allows us to trace the origin of placodes and their components back from ancestor to ancestor. Some of the core networks of ectodermal patterning and sensory and neurosecretory differentiation were already established in the common ancestor of cnidarians and bilaterians and were greatly elaborated in the bilaterian ancestor (with BMP- and Wnt-dependent patterning of dorsoventral and anteroposterior ectoderm and multiple neurosecretory and sensory cell types). Rostral and caudal protoplacodal domains, giving rise to some neurosecretory and sensory cells, were then established in the ectoderm of the chordate and tunicate-vertebrate ancestor, respectively. However, proper cranial placodes as clusters of proliferating progenitors producing high-density arrays of neurosecretory and sensory cells only evolved and diversified in the ancestors of vertebrates.
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Affiliation(s)
- Gerhard Schlosser
- School of Natural Sciences & Regenerative Medicine Institute (REMEDI), National University of Ireland, Galway, Ireland.
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27
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Petrovic J, Gálvez H, Neves J, Abelló G, Giraldez F. Differential regulation of Hes/Hey genes during inner ear development. Dev Neurobiol 2014; 75:703-20. [PMID: 25363712 DOI: 10.1002/dneu.22243] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 10/28/2014] [Indexed: 11/09/2022]
Abstract
Notch signaling plays a crucial role during inner ear development and regeneration. Hes/Hey genes encode for bHLH transcription factors identified as Notch targets. We have studied the expression and regulation of Hes/Hey genes during inner ear development in the chicken embryo. Among several Hes/Hey genes examined, only Hey1 and Hes5 map to the sensory regions, although with salient differences. Hey1 expression follows Jag1 expression except at early prosensory stages while Hes5 expression corresponds well to Dl1 expression throughout otic development. Although Hey1 and Hes5 are direct Notch downstream targets, they differ in the level of Notch required for activation. Moreover, they also differ in mRNA stability, showing different temporal decays after Notch blockade. In addition, Bmp, Wnt and Fgf pathways also modify Hey1 and Hes5 expression in the inner ear. Particularly, the Wnt pathway modulates Hey1 and Jag1 expression. Finally, gain of function experiments show that Hey1 and Hes5 cross-regulate each other in a complex manner. Both Hey1 and Hes5 repress Dl1 and Hes5 expression, suggesting that they prevent the transition to differentiation stages, probably by preventing Atoh1 expression. In spite of its association with Jag1, Hey1 does not seem to be instrumental for lateral induction as it does not promote Jag1 expression. We suggest that, besides being both targets of Notch, Hey1 and Hes5 are subject to a rather complex regulation that includes the stability of their transcripts, cross regulation and other signaling pathways.
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Affiliation(s)
- Jelena Petrovic
- Developmental Biology Unit, CEXS, Universitat Pompeu Fabra, Parc de Recerca Biomèdica de Barcelona (PRBB), Barcelona, Spain
| | - Hector Gálvez
- Developmental Biology Unit, CEXS, Universitat Pompeu Fabra, Parc de Recerca Biomèdica de Barcelona (PRBB), Barcelona, Spain
| | - Joana Neves
- Developmental Biology Unit, CEXS, Universitat Pompeu Fabra, Parc de Recerca Biomèdica de Barcelona (PRBB), Barcelona, Spain
| | - Gina Abelló
- Developmental Biology Unit, CEXS, Universitat Pompeu Fabra, Parc de Recerca Biomèdica de Barcelona (PRBB), Barcelona, Spain
| | - Fernando Giraldez
- Developmental Biology Unit, CEXS, Universitat Pompeu Fabra, Parc de Recerca Biomèdica de Barcelona (PRBB), Barcelona, Spain
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28
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Radosevic M, Fargas L, Alsina B. The role of her4 in inner ear development and its relationship with proneural genes and Notch signalling. PLoS One 2014; 9:e109860. [PMID: 25299450 PMCID: PMC4192589 DOI: 10.1371/journal.pone.0109860] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 09/08/2014] [Indexed: 01/13/2023] Open
Abstract
The generation of sensory neurons and hair cells of the inner ear is under tight control. Different members of the Hairy and Enhancer of Split genes (HES) are expressed in the inner ear, their full array of functions still not being disclosed. We have previously shown that zebrafish her9 acts as a patterning gene to restrict otic neurogenesis to an anterior domain. Here, we disclose the role of another her gene, her4, a zebrafish ortholog of Hes5 that is expressed in the neurogenic and sensory domains of the inner ear. The expression of her4 is highly dynamic and spatiotemporally regulated. We demonstrate by loss of function experiments that in the neurogenic domain her4 expression is under the regulation of neurogenin1 (neurog1) and the Notch pathway. Moreover, her4 participates in lateral inhibition during otic neurogenesis since her4 knockdown results in overproduction of the number of neurog1 and deltaB-positive otic neurons. In contrast, during sensorigenesis her4 is initially Notch-independent and induced by atoh1b in a broad prosensory domain. At later stages her4 expression becomes Notch-dependent in the future sensory domains but loss of her4 does not result in hair cell overproduction, suggesting that there other her genes can compensate its function.
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Affiliation(s)
- Marija Radosevic
- Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, Parc de Recerca Biomèdica de Barcelona, Barcelona, Spain
| | - Laura Fargas
- Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, Parc de Recerca Biomèdica de Barcelona, Barcelona, Spain
| | - Berta Alsina
- Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, Parc de Recerca Biomèdica de Barcelona, Barcelona, Spain
- * E-mail:
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29
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Yu Z, Wu S, Liu Z, Lin H, Chen L, Yuan X, Zhang Z, Liu F, Zhang C. Sonic Hedgehog and Retinoic Acid Induce Bone Marrow-Derived Stem Cells to Differentiate into Glutamatergic Neural Cells. J Immunoassay Immunochem 2014; 36:1-15. [DOI: 10.1080/15321819.2014.889025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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30
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Raft S, Groves AK. Segregating neural and mechanosensory fates in the developing ear: patterning, signaling, and transcriptional control. Cell Tissue Res 2014; 359:315-32. [PMID: 24902666 DOI: 10.1007/s00441-014-1917-6] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2014] [Accepted: 05/08/2014] [Indexed: 12/21/2022]
Abstract
The vertebrate inner ear is composed of multiple sensory receptor epithelia, each of which is specialized for detection of sound, gravity, or angular acceleration. Each receptor epithelium contains mechanosensitive hair cells, which are connected to the brainstem by bipolar sensory neurons. Hair cells and their associated neurons are derived from the embryonic rudiment of the inner ear epithelium, but the precise spatial and temporal patterns of their generation, as well as the signals that coordinate these events, have only recently begun to be understood. Gene expression, lineage tracing, and mutant analyses suggest that both neurons and hair cells are generated from a common domain of neural and sensory competence in the embryonic inner ear rudiment. Members of the Shh, Wnt, and FGF families, together with retinoic acid signals, regulate transcription factor genes within the inner ear rudiment to establish the axial identity of the ear and regionalize neurogenic activity. Close-range signaling, such as that of the Notch pathway, specifies the fate of sensory regions and individual cell types. We also describe positive and negative interactions between basic helix-loop-helix and SoxB family transcription factors that specify either neuronal or sensory fates in a context-dependent manner. Finally, we review recent work on inner ear development in zebrafish, which demonstrates that the relative timing of neurogenesis and sensory epithelial formation is not phylogenetically constrained.
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Affiliation(s)
- Steven Raft
- Section on Sensory Cell Regeneration and Development, National Institute on Deafness and Other Communication Disorders National Institutes of Health, 35 Convent Drive, Bethesda, MD, 20892, USA,
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31
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Sánchez-Guardado LÓ, Puelles L, Hidalgo-Sánchez M. Fate map of the chicken otic placode. Development 2014; 141:2302-12. [PMID: 24821982 DOI: 10.1242/dev.101667] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The inner ear is an intricate three-dimensional sensory organ that arises from a flat, thickened portion of the ectoderm termed the otic placode. There is evidence that the ontogenetic steps involved in the progressive specification of the highly specialized inner ear of vertebrates involve the concerted actions of diverse patterning signals that originate from nearby tissues, providing positional identity and instructive context. The topology of the prospective inner ear portions at placode stages when such patterning begins has remained largely unknown. The chick-quail model was used to perform a comprehensive fate mapping study of the chick otic placode, shedding light on the precise topological position of each presumptive inner ear component relative to the dorsoventral and anteroposterior axes of the otic placode and, implicitly, to the possible sources of inducing signals. The findings reveal the existence of three dorsoventrally arranged anteroposterior domains from which the endolymphatic system, the maculae and basilar papilla, and the cristae develop. This study provides new bases for the interpretation of earlier and future descriptive and experimental studies that aim to understand the molecular genetic mechanisms involved in otic placode patterning.
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Affiliation(s)
| | - Luis Puelles
- Department of Human Anatomy and Psychobiology, School of Medicine, University of Murcia, 30003 Murcia, Spain
| | - Matías Hidalgo-Sánchez
- Department of Cell Biology, Faculty of Science, University of Extremadura, 06071 Badajoz, Spain
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32
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Sienknecht UJ, Köppl C, Fritzsch B. Evolution and Development of Hair Cell Polarity and Efferent Function in the Inner Ear. BRAIN, BEHAVIOR AND EVOLUTION 2014; 83:150-61. [DOI: 10.1159/000357752] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Accepted: 12/03/2013] [Indexed: 11/19/2022]
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33
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Sensational placodes: neurogenesis in the otic and olfactory systems. Dev Biol 2014; 389:50-67. [PMID: 24508480 PMCID: PMC3988839 DOI: 10.1016/j.ydbio.2014.01.023] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Revised: 01/27/2014] [Accepted: 01/28/2014] [Indexed: 11/22/2022]
Abstract
For both the intricate morphogenetic layout of the sensory cells in the ear and the elegantly radial arrangement of the sensory neurons in the nose, numerous signaling molecules and genetic determinants are required in concert to generate these specialized neuronal populations that help connect us to our environment. In this review, we outline many of the proteins and pathways that play essential roles in the differentiation of otic and olfactory neurons and their integration into their non-neuronal support structures. In both cases, well-known signaling pathways together with region-specific factors transform thickened ectodermal placodes into complex sense organs containing numerous, diverse neuronal subtypes. Olfactory and otic placodes, in combination with migratory neural crest stem cells, generate highly specialized subtypes of neuronal cells that sense sound, position and movement in space, odors and pheromones throughout our lives.
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Patthey C, Schlosser G, Shimeld SM. The evolutionary history of vertebrate cranial placodes--I: cell type evolution. Dev Biol 2014; 389:82-97. [PMID: 24495912 DOI: 10.1016/j.ydbio.2014.01.017] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Revised: 01/21/2014] [Accepted: 01/24/2014] [Indexed: 10/25/2022]
Abstract
Vertebrate cranial placodes are crucial contributors to the vertebrate cranial sensory apparatus. Their evolutionary origin has attracted much attention from evolutionary and developmental biologists, yielding speculation and hypotheses concerning their putative homologues in other lineages and the developmental and genetic innovations that might have underlain their origin and diversification. In this article we first briefly review our current understanding of placode development and the cell types and structures they form. We next summarise previous hypotheses of placode evolution, discussing their strengths and caveats, before considering the evolutionary history of the various cell types that develop from placodes. In an accompanying review, we also further consider the evolution of ectodermal patterning. Drawing on data from vertebrates, tunicates, amphioxus, other bilaterians and cnidarians, we build these strands into a scenario of placode evolutionary history and of the genes, cells and developmental processes that underlie placode evolution and development.
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Affiliation(s)
- Cedric Patthey
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK.
| | - Gerhard Schlosser
- Zoology, School of Natural Sciences & Regenerative Medicine Institute (REMEDI), National University of Ireland, Galway, University Road, Galway, Ireland
| | - Sebastian M Shimeld
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK
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Ectopic expression of activated notch or SOX2 reveals similar and unique roles in the development of the sensory cell progenitors in the mammalian inner ear. J Neurosci 2013; 33:16146-57. [PMID: 24107947 DOI: 10.1523/jneurosci.3150-12.2013] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Hearing impairment or vestibular dysfunction in humans often results from a permanent loss of critical cell types in the sensory regions of the inner ear, including hair cells, supporting cells, or cochleovestibular neurons. These important cell types arise from a common sensory or neurosensory progenitor, although little is known about how these progenitors are specified. Studies have shown that Notch signaling and the transcription factor Sox2 are required for the development of these lineages. Previously we and others demonstrated that ectopic activation of Notch can direct nonsensory cells to adopt a sensory fate, indicating a role for Notch in early specification events. Here, we explore the relationship between Notch and SOX2 by ectopically activating these factors in nonsensory regions of the mouse cochlea, and demonstrate that, similar to Notch, SOX2 can specify sensory progenitors, consistent with a role downstream of Notch signaling. However, we also show that Notch has a unique role in promoting the proliferation of the sensory progenitors. We further demonstrate that Notch can only induce ectopic sensory regions within a certain time window of development, and that the ectopic hair cells display specialized stereocilia bundles similar to endogenous hair cells. These results demonstrate that Notch and SOX2 can both drive the sensory program in nonsensory cells, indicating these factors may be useful in cell replacement strategies in the inner ear.
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Jiang H, Wang L, Beier KT, Cepko CL, Fekete DM, Brigande JV. Lineage analysis of the late otocyst stage mouse inner ear by transuterine microinjection of a retroviral vector encoding alkaline phosphatase and an oligonucleotide library. PLoS One 2013; 8:e69314. [PMID: 23935981 PMCID: PMC3723842 DOI: 10.1371/journal.pone.0069314] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Accepted: 06/12/2013] [Indexed: 12/23/2022] Open
Abstract
The mammalian inner ear subserves the special senses of hearing and balance. The auditory and vestibular sensory epithelia consist of mechanically sensitive hair cells and associated supporting cells. Hearing loss and balance dysfunction are most frequently caused by compromise of hair cells and/or their innervating neurons. The development of gene- and cell-based therapeutics will benefit from a thorough understanding of the molecular basis of patterning and cell fate specification in the mammalian inner ear. This includes analyses of cell lineages and cell dispersals across anatomical boundaries (such as sensory versus nonsensory territories). The goal of this study was to conduct retroviral lineage analysis of the embryonic day 11.5(E11.5) mouse otic vesicle. A replication-defective retrovirus encoding human placental alkaline phosphatase (PLAP) and a variable 24-bp oligonucleotide tag was microinjected into the E11.5 mouse otocyst. PLAP-positive cells were microdissected from cryostat sections of the postnatal inner ear and subjected to nested PCR. PLAP-positive cells sharing the same sequence tag were assumed to have arisen from a common progenitor and are clonally related. Thirty five multicellular clones consisting of an average of 3.4 cells per clone were identified in the auditory and vestibular sensory epithelia, ganglia, spiral limbus, and stria vascularis. Vestibular hair cells in the posterior crista were related to one another, their supporting cells, and nonsensory epithelial cells lining the ampulla. In the organ of Corti, outer hair cells were related to a supporting cell type and were tightly clustered. By contrast, spiral ganglion neurons, interdental cells, and Claudius' cells were related to cells of the same type and could be dispersed over hundreds of microns. These data contribute new information about the developmental potential of mammalian otic precursors in vivo.
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Affiliation(s)
- Han Jiang
- Department of Otolaryngology, Oregon Hearing Research Center, Oregon Health & Science University, Portland, Oregon, United States of America
- Jilin Province Key Laboratory of Animal Embryo Engineering, College of Animal Science and Veterinary Medicine, Jilin University, Changchun, China
| | - Lingyan Wang
- Department of Otolaryngology, Oregon Hearing Research Center, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Kevin T. Beier
- Department of Genetics, Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Constance L. Cepko
- Department of Genetics, Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Donna M. Fekete
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana, United States of America
| | - John V. Brigande
- Department of Otolaryngology, Oregon Hearing Research Center, Oregon Health & Science University, Portland, Oregon, United States of America
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Hans S, Irmscher A, Brand M. Zebrafish Foxi1 provides a neuronal ground state during inner ear induction preceding the Dlx3b/4b-regulated sensory lineage. Development 2013; 140:1936-45. [PMID: 23571216 DOI: 10.1242/dev.087718] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Vertebrate inner ear development is a complex process that involves the induction of a common territory for otic and epibranchial precursors and their subsequent segregation into otic and epibranchial cell fates. In zebrafish, the otic-epibranchial progenitor domain (OEPD) is induced by Fgf signaling in a Foxi1- and Dlx3b/4b-dependent manner, but the functional differences of Foxi1 and Dlx3b/4b in subsequent cell fate specifications within the developing inner ear are poorly understood. Based on pioneer tracking (PioTrack), a novel Cre-dependent genetic lineage tracing method, and genetic data, we show that the competence to embark on a neuronal or sensory fate is provided sequentially and very early during otic placode induction. Loss of Foxi1 prevents neuronal precursor formation without affecting hair cell specification, whereas loss of Dlx3b/4b inhibits hair cell but not neuronal precursor formation. Consistently, in Dlx3b/4b- and Sox9a-deficient b380 mutants almost all otic epithelial fates are absent, including sensory hair cells, and the remaining otic cells adopt a neuronal fate. Furthermore, the progenitors of the anterior lateral line ganglia also arise from the OEPD in a Foxi1-dependent manner but are unaffected in the absence of Dlx3b/4b or in b380 mutants. Thus, in addition to otic fate Foxi1 provides neuronal competence during OEPD induction prior to and independently of the Dlx3b/4b-mediated sensory fate of the developing inner ear.
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Affiliation(s)
- Stefan Hans
- Technische Universität Dresden, Biotechnology Center and DFG-Center for Regenerative Therapies Dresden Cluster of Excellence, Tatzberg 47-49, Dresden, Germany.
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Kiernan AE. Notch signaling during cell fate determination in the inner ear. Semin Cell Dev Biol 2013; 24:470-9. [PMID: 23578865 DOI: 10.1016/j.semcdb.2013.04.002] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 03/27/2013] [Accepted: 04/02/2013] [Indexed: 01/05/2023]
Abstract
In the inner ear, Notch signaling has been proposed to specify the sensory regions, as well as regulate the differentiation of hair cells and supporting cell within those regions. In addition, Notch plays an important role in otic neurogenesis, by determining which cells differentiate as neurons, sensory cells and non-sensory cells. Here, I review the evidence for the complex and myriad roles Notch participates in during inner ear development. A particular challenge for those studying ear development and Notch is to decipher how activation of a single pathway can lead to different outcomes within the ear, which may include changes in the intrinsic properties of the cell, Notch modulation, and potential non-canonical pathways.
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Affiliation(s)
- Amy E Kiernan
- Department of Ophthalmology, University of Rochester, Rochester, NY 14642, United States.
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Neves J, Vachkov I, Giraldez F. Sox2 regulation of hair cell development: incoherence makes sense. Hear Res 2013; 297:20-9. [DOI: 10.1016/j.heares.2012.11.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Revised: 10/17/2012] [Accepted: 11/05/2012] [Indexed: 01/09/2023]
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The amniote paratympanic organ develops from a previously undiscovered sensory placode. Nat Commun 2013; 3:1041. [PMID: 22948823 PMCID: PMC3518548 DOI: 10.1038/ncomms2036] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Accepted: 07/31/2012] [Indexed: 11/25/2022] Open
Abstract
The paratympanic organ (PTO), a mechanosensory hair cell-containing pouch in the amniote middle ear, was first described 100 years ago yet its origins remain unresolved. Homology with the anamniote spiracular organ is supported by association with homologous skeletal elements and similar central targets of afferent neurons, suggesting it might be a remnant of the water-dependent lateral line system, otherwise lost during the amniote transition to terrestrial life. However, this is incompatible with studies suggesting it arises from the first epibranchial (geniculate) placode. Here we show that a previously undiscovered Sox2-positive placode, immediately dorsal to the geniculate placode, forms the PTO and its afferent neurons, which are molecularly and morphologically distinct from geniculate neurons. These data remove the only obstacle to accepting the homology of the PTO and spiracular organ. We hypothesise that the PTO/spiracular organ represents an ancient head ectoderm module, developmentally and evolutionarily independent of both lateral line and epibranchial placodes.
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41
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Cell lineage analysis reveals three different progenitor pools for neurosensory elements in the otic vesicle. J Neurosci 2013; 32:16424-34. [PMID: 23152625 DOI: 10.1523/jneurosci.3686-12.2012] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
In the inner ear, sensory versus neuronal specification is achieved through few well-defined bHLH transcription factors. However, the molecular mechanisms regulating the generation of the appropriate cell type in the correct place and at the correct time are not completely understood yet. Various studies have shown that hair cell- and neuron-specifying genes partially overlap in the otic territory, suggesting that mutual interactions among these bHLH factors could direct the generation of the two cell types from a common neurosensory progenitor. Although there is little evidence for a clonal relationship between macular hair cells and sensory neurons, the existence of a single progenitor able to give both sensory and neuronal cell types remains an open question. Here, we identified a population of common neurosensory progenitors in the zebrafish inner ear and studied the proneural requirement for cell fate decision within this population. Expression analysis reveals that proneural genes for hair cells and neurons overlap within the posteromedial otic epithelium. Combined results from single-cell lineage and functional studies on neurog1 and neuroD1 further demonstrate the following: (1) in the anterior region of the ear, neuronal and sensory lineages have already segregated at the onset of proneural gene expression and are committed to a given fate very early; (2) in contrast, the posteromedial part of the ear harbors a population of common progenitors giving both neurons and hair cells until late stages; and finally (3) neuroD1 is required within this pool of bipotent progenitors to generate the hair cell fate.
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42
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Origin and Development of Hair Cell Orientation in the Inner Ear. INSIGHTS FROM COMPARATIVE HEARING RESEARCH 2013. [DOI: 10.1007/2506_2013_28] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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43
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O'Neill P. Magnetoreception and baroreception in birds. Dev Growth Differ 2012; 55:188-97. [DOI: 10.1111/dgd.12025] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Revised: 11/01/2012] [Accepted: 11/01/2012] [Indexed: 11/28/2022]
Affiliation(s)
- Paul O'Neill
- Laboratory for Sensory Development; RIKEN Center for Developmental Biology; 2-2-3 Minatojima-Minamimachi, Chuo-ku; Kobe; 650-0047; Japan
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44
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Neves J, Abelló G, Petrovic J, Giraldez F. Patterning and cell fate in the inner ear: a case for Notch in the chicken embryo. Dev Growth Differ 2012; 55:96-112. [PMID: 23252974 DOI: 10.1111/dgd.12016] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2012] [Revised: 10/09/2012] [Accepted: 10/09/2012] [Indexed: 01/08/2023]
Abstract
The development of the inner ear provides a beautiful example of one basic problem in development, that is, to understand how different cell types are generated at specific times and domains throughout embryonic life. The functional unit of the inner ear consists of hair cells, supporting cells and neurons, all deriving from progenitor cells located in the neurosensory competent domain of the otic placode. Throughout development, the otic placode resolves into the complex inner ear labyrinth, which holds the auditory and vestibular sensory organs that are innervated in a highly specific manner. How does the early competent domain of the otic placode give rise to the diverse specialized cell types of the different sensory organs of the inner ear? We review here our current understanding on the role of Notch signaling in coupling patterning and cell fate determination during inner ear development, with a particular emphasis on contributions from the chicken embryo as a model organism. We discuss further the question of how these two processes rely on two modes of operation of the Notch signaling pathway named lateral induction and lateral inhibition.
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Affiliation(s)
- Joana Neves
- CEXS, Universitat Pompeu Fabra, Parc de Recerca Biomèdica de Barcelona, Barcelona, Spain
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45
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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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46
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Durán Alonso MB, Feijoo-Redondo A, Conde de Felipe M, Carnicero E, García AS, García-Sancho J, Rivolta MN, Giráldez F, Schimmang T. Generation of inner ear sensory cells from bone marrow-derived human mesenchymal stem cells. Regen Med 2012; 7:769-783. [PMID: 23164078 DOI: 10.2217/rme.12.65] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
AIM Hearing loss is the most common sensory disorder in humans, its main cause being the loss of cochlear hair cells. We studied the potential of human mesenchymal stem cells (hMSCs) to differentiate towards hair cells and auditory neurons. MATERIALS & METHODS hMSCs were first differentiated to neural progenitors and subsequently to hair cell- or auditory neuron-like cells using in vitro culture methods. RESULTS Differentiation of hMSCs to an intermediate neural progenitor stage was critical for obtaining inner ear sensory lineages. hMSCs generated hair cell-like cells only when neural progenitors derived from nonadherent hMSC cultures grown in serum-free medium were exposed to EGF and retinoic acid. Auditory neuron-like cells were obtained when treated with retinoic acid, and in the presence of defined growth factor combinations containing Sonic Hedgehog. CONCLUSION The results show the potential of hMSCs to give rise to inner ear sensory cells.
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Affiliation(s)
- M Beatriz Durán Alonso
- Instituto de Biología y Genética Molecular, Universidad de Valladolid y Consejo Superior de Investigaciones Científicas, C/Sanz y Forés 3, E-47003, Valladolid, Spain.
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47
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Duncan JS, Fritzsch B. Evolution of Sound and Balance Perception: Innovations that Aggregate Single Hair Cells into the Ear and Transform a Gravistatic Sensor into the Organ of Corti. Anat Rec (Hoboken) 2012; 295:1760-74. [DOI: 10.1002/ar.22573] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Accepted: 07/24/2012] [Indexed: 01/20/2023]
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48
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Magariños M, Contreras J, Aburto MR, Varela-Nieto I. Early development of the vertebrate inner ear. Anat Rec (Hoboken) 2012; 295:1775-90. [PMID: 23044927 DOI: 10.1002/ar.22575] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Accepted: 07/24/2012] [Indexed: 12/12/2022]
Abstract
This is a review of the biological processes and the main signaling pathways required to generate the different otic cell types, with particular emphasis on the actions of insulin-like growth factor I. The sensory organs responsible of hearing and balance have a common embryonic origin in the otic placode. Lineages of neural, sensory, and support cells are generated from common otic neuroepithelial progenitors. The sequential generation of the cell types that will form the adult inner ear requires the coordination of cell proliferation with cell differentiation programs, the strict regulation of cell survival, and the metabolic homeostasis of otic precursors. A network of intracellular signals operates to coordinate the transcriptional response to the extracellular input. Understanding the molecular clues that direct otic development is fundamental for the design of novel treatments for the protection and repair of hearing loss and balance disorders.
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Affiliation(s)
- Marta Magariños
- Instituto de Investigaciones Biomédicas, Alberto Sols, CSIC-UAM, Madrid, Spain
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49
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Giannessi F, Ruffoli R, von Bartheld CS. Giovanni Vitali: Discoverer of the paratympanic organ. Ann Anat 2012; 195:5-10. [PMID: 22999077 DOI: 10.1016/j.aanat.2012.06.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Revised: 06/25/2012] [Accepted: 06/27/2012] [Indexed: 11/25/2022]
Abstract
One-hundred years ago, the Italian anatomist Giovanni Vitali reported the discovery of the paratympanic organ, a sense organ in the middle ear of birds, in two issues of the Anatomischer Anzeiger (1911, 1912). In this minireview, we summarize Vitali's biography, and examine the scientific impact of his discovery of this sense organ. We also compile - for the first time - the entire bibliography of published papers on the paratympanic organ. Vitali described the ontogenetic development of this sense organ, examined its distribution among species, recognized its evolutionary relationship with the spiracular sense organ of fishes, and he developed the theory that it functions as a detector of changes in air pressure. He was the first to postulate that the paratympanic and spiracular sense organs were homologous organs that originate from homologous placodes - currently a hotly debated topic. His morphological work indicating the sensory nature of the PTO was validated by subsequent ultrastructural studies. Vitali's discovery of the paratympanic organ prompted his nomination for the Nobel Prize in 1934. Nevertheless, the paratympanic organ and the presumed barometric sense of hundreds of billions of living birds have failed to receive the recognition they deserve. Conclusive evidence of the function of the paratympanic organ remains a formidable challenge in vertebrate sensory physiology.
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Affiliation(s)
- Francesco Giannessi
- Department of Human Morphology and Applied Biology, Faculty of Medicine and Surgery, University of Pisa, Italy.
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Abstract
The inner ear is a structurally complex vertebrate organ built to encode sound, motion, and orientation in space. Given its complexity, it is not surprising that inner ear dysfunction is a relatively common consequence of human genetic mutation. Studies in model organisms suggest that many genes currently known to be associated with human hearing impairment are active during embryogenesis. Hence, the study of inner ear development provides a rich context for understanding the functions of genes implicated in hearing loss. This chapter focuses on molecular mechanisms of inner ear development derived from studies of model organisms.
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Affiliation(s)
- Doris K Wu
- National Institute on Deafness and Other Communication Disorders, Rockville, Maryland 20850, USA.
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