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Wang SX, Streit A. Shared features in ear and kidney development - implications for oto-renal syndromes. Dis Model Mech 2024; 17:dmm050447. [PMID: 38353121 PMCID: PMC10886756 DOI: 10.1242/dmm.050447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2024] Open
Abstract
The association between ear and kidney anomalies has long been recognized. However, little is known about the underlying mechanisms. In the last two decades, embryonic development of the inner ear and kidney has been studied extensively. Here, we describe the developmental pathways shared between both organs with particular emphasis on the genes that regulate signalling cross talk and the specification of progenitor cells and specialised cell types. We relate this to the clinical features of oto-renal syndromes and explore links to developmental mechanisms.
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Affiliation(s)
- Scarlet Xiaoyan Wang
- Centre for Craniofacial and Regenerative Biology, King's College London, London SE1 9RT, UK
| | - Andrea Streit
- Centre for Craniofacial and Regenerative Biology, King's College London, London SE1 9RT, UK
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2
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Rochais F, Kelly RG. Fibroblast growth factor 10. Differentiation 2023:100741. [PMID: 38040515 DOI: 10.1016/j.diff.2023.100741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 11/16/2023] [Accepted: 11/21/2023] [Indexed: 12/03/2023]
Abstract
Fibroblast growth factor 10 (FGF10) is a major morphoregulatory factor that plays essential signaling roles during vertebrate multiorgan development and homeostasis. FGF10 is predominantly expressed in mesenchymal cells and signals though FGFR2b in adjacent epithelia to regulate branching morphogenesis, stem cell fate, tissue differentiation and proliferation, in addition to autocrine roles. Genetic loss of function analyses have revealed critical requirements for FGF10 signaling during limb, lung, digestive system, ectodermal, nervous system, craniofacial and cardiac development. Heterozygous FGF10 mutations have been identified in human genetic syndromes associated with craniofacial anomalies, including lacrimal and salivary gland aplasia. Elevated Fgf10 expression is associated with poor prognosis in a range of cancers. In addition to developmental and disease roles, FGF10 regulates homeostasis and repair of diverse adult tissues and has been identified as a target for regenerative medicine.
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Affiliation(s)
| | - Robert G Kelly
- Aix-Marseille Université, CNRS UMR 7288, IBDM, Marseille, France.
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3
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Song H, Morrow BE. Tbx2 and Tbx3 regulate cell fate progression of the otic vesicle for inner ear development. Dev Biol 2023; 494:71-84. [PMID: 36521641 PMCID: PMC9870991 DOI: 10.1016/j.ydbio.2022.12.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 12/05/2022] [Accepted: 12/10/2022] [Indexed: 12/14/2022]
Abstract
The morphogenesis of the otic vesicle (OV) to form inner ear organs serves as an excellent model system to understand cell fate acquisition on a single cell level. Tbx2 and Tbx3 (Tbx2/3) encode closely related T-box transcription factors that are expressed widely in the mammalian OV. Inactivation of both genes in the OV (Tbx2/3cKO) results in failed morphogenesis into inner ear organs. To understand the basis of these defects, single cell RNA-sequencing (scRNA-seq) was performed on the OV lineage, in controls versus Tbx2/3cKO embryos. We identified a multipotent population termed otic progenitors in controls that are marked by expression of the known otic placode markers Eya1, Sox2, and Sox3 as well as new markers Fgf18, Cxcl12, and Pou3f3. The otic progenitor population was increased three-fold in Tbx2/3cKO embryos, concomitant with dysregulation of genes in these cells as well as reduced progression to more differentiated states of prosensory and nonsensory cells. An ectopic neural population of cells was detected in the posterior OV of Tbx2/3cKO embryos but had reduced maturation to delaminated neural cells. As all three cell fates were affected in Tbx2/3cKO embryos, we suggest that Tbx2/3 promotes progression of multipotent otic progenitors to more differentiated cell types in the OV.
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Affiliation(s)
- Hansoo Song
- Department of Genetics, Albert Einstein College of Medicine, 1301 Morris Park Ave., Bronx, NY, USA
| | - Bernice E Morrow
- Department of Genetics, Albert Einstein College of Medicine, 1301 Morris Park Ave., Bronx, NY, USA.
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4
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Yang H, Ryu J, Lim C, Choi JW, Park YJ, Jang SW, Shim S. SOXE group transcription factors regulates the expression of FoxG1 during inner ear development. Biochem Biophys Res Commun 2022; 623:96-103. [PMID: 35878429 DOI: 10.1016/j.bbrc.2022.07.048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 07/13/2022] [Indexed: 11/24/2022]
Abstract
The transcription factor FOXG1 plays an important role in inner ear development; however, the cis-regulatory mechanisms controlling the inner-ear-specific expression of FOXG1 are poorly understood. In this study, we aimed to identify the element that specifically regulates FoxG1 expression in the otic vesicle, which develops into the inner ear, through comparative genome analysis between vertebrate species and chromatin immunoprecipitation. The cis-regulatory element (E2) identified showed high evolutionary conservation among vertebrates in the genomic DNA of FoxG1 spanning approximately 3 Mbp. We identified core sequences important for the activity of the otic-vesicle-specific enhancer through in vitro and in vivo reporter assays for various E2 enhancer mutants and determined the consensus sequence for SOX DNA binding. In addition, SoxE, a subfamily of the Sox family, was simultaneously expressed in the otic vesicles of developing embryos and showed a similar protein expression pattern as that of FoxG1. Furthermore, SOXE transcription factors induced specific transcriptional activity through the FoxG1 Otic enhancer (E2b). These findings suggest that the interaction between the otic enhancer of FoxG1 and SOXE transcription factor, in which the otic expression of FoxG1 is evolutionarily well-conserved, is important during early development of the inner ear, a sensory organ important for survival in nature.
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Affiliation(s)
- Hayoung Yang
- Department of Biochemistry, Chungbuk National University, Cheongju, 28644, Republic of Korea
| | - Jiho Ryu
- Department of Biochemistry, Chungbuk National University, Cheongju, 28644, Republic of Korea
| | - Chungun Lim
- Department of Biomedical Sciences, University of Ulsan College of Medicine, Seoul, 05505, Republic of Korea
| | - Jae-Won Choi
- Division of BT Convergence, Cheongju University, Cheongju, 28503, Republic of Korea
| | - Young-Jun Park
- Immunotherapy Research Center, Korea Research Institute of Bioscience and Biotechnology, Yuseong-gu, Daejeon, Republic of Korea
| | - Sung-Wuk Jang
- Department of Biomedical Sciences, University of Ulsan College of Medicine, Seoul, 05505, Republic of Korea; Asan Medical Institute of Convergence Science and Technology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, 138-736, Republic of Korea.
| | - Sungbo Shim
- Department of Biochemistry, Chungbuk National University, Cheongju, 28644, Republic of Korea.
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5
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Johnson Chacko L, Sergi C, Eberharter T, Dudas J, Rask-Andersen H, Hoermann R, Fritsch H, Fischer N, Glueckert R, Schrott-Fischer A. Early appearance of key transcription factors influence the spatiotemporal development of the human inner ear. Cell Tissue Res 2019; 379:459-471. [PMID: 31788757 DOI: 10.1007/s00441-019-03115-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Accepted: 09/22/2019] [Indexed: 12/11/2022]
Abstract
Expression patterns of transcription factors leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5), transforming growth factor-β-activated kinase-1 (TAK1), SRY (sex-determining region Y)-box 2 (SOX2), and GATA binding protein 3 (GATA3) in the developing human fetal inner ear were studied between the gestation weeks 9 and 12. Further development of cochlear apex between gestational weeks 11 and 16 (GW11 and GW16) was examined using transmission electron microscopy. LGR5 was evident in the apical poles of the sensory epithelium of the cochlear duct and the vestibular end organs at GW11. Immunostaining was limited to hair cells of the organ of Corti by GW12. TAK1 was immune positive in inner hair cells of the organ of Corti by GW12 and colocalized with p75 neurotrophic receptor expression. Expression for SOX2 was confined primarily to the supporting cells of utricle at the earliest stage examined at GW9. Intense expression for GATA3 was presented in the cochlear sensory epithelium and spiral ganglia at GW9. Expression of GATA3 was present along the midline of both the utricle and saccule in the zone corresponding to the striolar reversal zone where the hair cell phenotype switches from type I to type II. The spatiotemporal gradient of the development of the organ of Corti was also evident with the apex of the cochlea forming by GW16. It seems that highly specific staining patterns of several transcriptions factors are critical in guiding the genesis of the inner ear over development. Our findings suggest that the spatiotemporal gradient in cochlear development extends at least until gestational week 16.
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Affiliation(s)
- Lejo Johnson Chacko
- Department of Otorhinolaryngology, Medical University of Innsbruck, Anichstrasse 35, 6020, Innsbruck, Austria
| | - Consolato Sergi
- Department of Laboratory Medicine and Pathology and Department of Pediatrics, University of Alberta, 8440 112 St, NW, Edmonton, AB, T6G 2B7, Canada
| | - Theresa Eberharter
- Department of Otorhinolaryngology, Medical University of Innsbruck, Anichstrasse 35, 6020, Innsbruck, Austria
| | - Jozsef Dudas
- Department of Otorhinolaryngology, Medical University of Innsbruck, Anichstrasse 35, 6020, Innsbruck, Austria
| | - Helge Rask-Andersen
- Department of Surgical Sciences, Head and Neck Surgery, Section of Otolaryngology, Uppsala University Hospital, SE-751 85, Uppsala, Sweden
| | - Romed Hoermann
- Department of Anatomy, Histology & Embryology, Division of Clinical & Functional Anatomy, Medical University of Innsbruck, Muellerstrasse 59, 6020, Innsbruck, Austria
| | - Helga Fritsch
- Department of Anatomy, Histology & Embryology, Division of Clinical & Functional Anatomy, Medical University of Innsbruck, Muellerstrasse 59, 6020, Innsbruck, Austria
| | - Natalie Fischer
- University Clinics Innsbruck, Tirol Kliniken, Anichstrasse 35, 6020, Innsbruck, Austria
| | - Rudolf Glueckert
- Department of Otorhinolaryngology, Medical University of Innsbruck, Anichstrasse 35, 6020, Innsbruck, Austria
- University Clinics Innsbruck, Tirol Kliniken, Anichstrasse 35, 6020, Innsbruck, Austria
| | - Anneliese Schrott-Fischer
- Department of Otorhinolaryngology, Medical University of Innsbruck, Anichstrasse 35, 6020, Innsbruck, Austria.
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6
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Bardhan T, Jeng J, Waldmann M, Ceriani F, Johnson SL, Olt J, Rüttiger L, Marcotti W, Holley MC. Gata3 is required for the functional maturation of inner hair cells and their innervation in the mouse cochlea. J Physiol 2019; 597:3389-3406. [PMID: 31069810 PMCID: PMC6636704 DOI: 10.1113/jp277997] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 05/07/2019] [Indexed: 01/14/2023] Open
Abstract
KEY POINTS The physiological maturation of auditory hair cells and their innervation requires precise temporal and spatial control of cell differentiation. The transcription factor gata3 is essential for the earliest stages of auditory system development and for survival and synaptogenesis in auditory sensory afferent neurons. We show that during postnatal development in the mouse inner ear gata3 is required for the biophysical maturation, growth and innervation of inner hair cells; in contrast, it is required only for the survival of outer hair cells. Loss of gata3 in inner hair cells causes progressive hearing loss and accounts for at least some of the deafness associated with the human hypoparathyroidism, deafness and renal anomaly (HDR) syndrome. The results show that gata3 is critical for later stages of mammalian auditory system development where it plays distinct, complementary roles in the coordinated maturation of sensory hair cells and their innervation. ABSTRACT The zinc finger transcription factor gata3 regulates inner ear development from the formation of the embryonic otic placode. Throughout development, gata3 is expressed dynamically in all the major cochlear cell types. Its role in afferent formation is well established but its possible involvement in hair cell maturation remains unknown. Here, we find that in heterozygous gata3 null mice (gata3+/- ) outer hair cells (OHCs) differentiate normally but their numbers are significantly lower. In contrast, inner hair cells (IHCs) survive normally but they fail to acquire adult basolateral membrane currents, retain pre-hearing current and efferent innervation profiles and have fewer ribbon synapses. Targeted deletion of gata3 driven by otoferlin-cre recombinase (gata3fl/fl otof-cre+/- ) in IHCs does not affect OHCs or the number of IHC afferent synapses but it leads to a failure in IHC maturation comparable to that observed in gata3+/- mice. Auditory brainstem responses in gata3fl/fl otof-cre+/- mice reveal progressive hearing loss that becomes profound by 6-7 months, whilst distortion product otoacoustic emissions are no different to control animals up to this age. Our results, alongside existing data, indicate that gata3 has specific, complementary functions in different cell types during inner ear development and that its continued expression in the sensory epithelium orchestrates critical aspects of physiological development and neural connectivity. Furthermore, our work indicates that hearing loss in human hypoparathyroidism, deafness and renal anomaly (HDR) syndrome arises from functional deficits in IHCs as well as loss of function from OHCs and both afferent and efferent neurons.
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MESH Headings
- Animals
- Cell Differentiation/physiology
- Cochlea/metabolism
- Cochlea/physiology
- GATA3 Transcription Factor/metabolism
- Hair Cells, Auditory, Inner/metabolism
- Hair Cells, Auditory, Inner/physiology
- Hair Cells, Auditory, Outer/metabolism
- Hair Cells, Auditory, Outer/physiology
- Hair Cells, Vestibular/metabolism
- Hair Cells, Vestibular/physiology
- Hearing/physiology
- Hearing Loss/metabolism
- Hearing Loss/physiopathology
- Membrane Proteins/metabolism
- Mice, Knockout
- Mice, Transgenic
- Sensory Receptor Cells/metabolism
- Sensory Receptor Cells/physiology
- Synapses/metabolism
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Affiliation(s)
- Tanaya Bardhan
- Department of Biomedical ScienceUniversity of SheffieldSheffieldUK
| | - Jing‐Yi Jeng
- Department of Biomedical ScienceUniversity of SheffieldSheffieldUK
| | - Marco Waldmann
- Department of OtolaryngologyTübingen Hearing Research CenterSection of Physiological Acoustics and CommunicationUniversity of Tübingen72076TübingenGermany
| | - Federico Ceriani
- Department of Biomedical ScienceUniversity of SheffieldSheffieldUK
| | | | - Jennifer Olt
- Department of Biomedical ScienceUniversity of SheffieldSheffieldUK
| | - Lukas Rüttiger
- Department of OtolaryngologyTübingen Hearing Research CenterSection of Physiological Acoustics and CommunicationUniversity of Tübingen72076TübingenGermany
| | - Walter Marcotti
- Department of Biomedical ScienceUniversity of SheffieldSheffieldUK
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7
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Ma JH, Kim HP, Shin JO. CTCF deficiency causes expansion of the sensory domain in the mouse cochlea. Biochem Biophys Res Commun 2019; 512:896-901. [PMID: 30929920 DOI: 10.1016/j.bbrc.2019.03.127] [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: 03/15/2019] [Accepted: 03/19/2019] [Indexed: 01/08/2023]
Abstract
The cochlea in the mammalian inner ear is a sensitive and sharply organized sound-detecting structure. The proper specification of neurosensory-competent domain in the otic epithelium is required for the formation of mature neuronal and sensory domains. Genetic studies have provided many insights into inner ear development, but there have been few epigenetic studies of inner ear development. CTCF is an epigenetic factor that plays a pivotal role in the organization of global chromatin conformation. To determine the role of CTCF in the otic sensory formation, we made a conditional knockout of Ctcf in the developing otic epithelium by crossing Ctcffl/fl mice with Pax2-Cre mice. Ctcf deficiency resulted in extra rows of auditory hair cells in the shortened cochlea on mouse embryonic day 14.5 (E14.5) and E17.5. The massive and ectopic expression of sensory specifiers such as Jag1 and Sox2 indicated that the sensory domain was expanded in the Ctcf-deficient cochlea. Other regulators of the sensory domain such as Bmp4, Gata3, and Fgf10 were not affected. These results suggest that CTCF plays a role in the regulation of the sensory domain in mammalian cochlear development.
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Affiliation(s)
- Ji-Hyun Ma
- Department of Anatomy, Yonsei University College of Medicine, Seoul, 03722, Republic of Korea
| | - Hyoung-Pyo Kim
- Department of Environmental Medical Biology, Yonsei University College of Medicine, Seoul, 03722, Republic of Korea; BK21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul, 03722, Republic of Korea
| | - Jeong-Oh Shin
- Department of Anatomy, Yonsei University College of Medicine, Seoul, 03722, Republic of Korea.
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8
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Kawakami H, Johnson A, Fujita Y, Swearer A, Wada N, Kawakami Y. Characterization of cis-regulatory elements for Fgf10 expression in the chick embryo. Dev Dyn 2018; 247:1253-1263. [PMID: 30325084 DOI: 10.1002/dvdy.24682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 09/28/2018] [Accepted: 10/11/2018] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND Fgf10 is expressed in various tissues and organs, such as the limb bud, heart, inner ear, and head mesenchyme. Previous studies identified Fgf10 enhancers for the inner ear and heart. However, Fgf10 enhancers for other tissues have not been identified. RESULTS By using primary culture chick embryo lateral plate mesoderm cells, we compared activities of deletion constructs of the Fgf10 promoter region, cloned into a promoter-less luciferase reporter vector. We identified a 0.34-kb proximal promoter that can activate luciferase expression. Then, we cloned 11 evolutionarily conserved sequences located within or outside of the Fgf10 gene into the 0.34-kb promoter-luciferase vector, and tested their activities in vitro using primary cultured cells. Two sequences showed the highest activities. By using the Tol2 system and electroporation into chick embryos, activities of the 0.34-kb promoter with and without the two sequences were tested in vivo. No activities were detected in limb buds. However, the 0.34-kb promoter exhibited activities in the dorsal midline of the brain, while Fgf10 is detected in broader region in the brain. The two noncoding sequences negatively acted on the 0.34-kb promoter in the brain. CONCLUSIONS The proximal 0.34-kb promoter has activities to drive expression in restricted areas of the brain. Developmental Dynamics 247:1253-1263, 2018. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Hiroko Kawakami
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota.,Stem Cell Institute, University of Minnesota, Minneapolis, Minnesota.,Developmental Biology Center, University of Minnesota, Minneapolis, Minnesota
| | - Austin Johnson
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota
| | - Yu Fujita
- Department of Applied Biological Science, Tokyo University of Science, Noda, Chiba, Japan
| | - Avery Swearer
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota
| | - Naoyuki Wada
- Department of Applied Biological Science, Tokyo University of Science, Noda, Chiba, Japan
| | - Yasuhiko Kawakami
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota.,Stem Cell Institute, University of Minnesota, Minneapolis, Minnesota.,Developmental Biology Center, University of Minnesota, Minneapolis, Minnesota
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9
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Romero-Guevara R, Cencetti F, Donati C, Bruni P. Sphingosine 1-phosphate signaling pathway in inner ear biology. New therapeutic strategies for hearing loss? Front Aging Neurosci 2015; 7:60. [PMID: 25954197 PMCID: PMC4407579 DOI: 10.3389/fnagi.2015.00060] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 04/08/2015] [Indexed: 12/13/2022] Open
Abstract
Hearing loss is one of the most prevalent conditions around the world, in particular among people over 60 years old. Thus, an increase of this affection is predicted as result of the aging process in our population. In this context, it is important to further explore the function of molecular targets involved in the biology of inner ear sensory cells to better individuate new candidates for therapeutic application. One of the main causes of deafness resides into the premature death of hair cells and auditory neurons. In this regard, neurotrophins and growth factors such as insulin like growth factor are known to be beneficial by favoring the survival of these cells. An elevated number of published data in the last 20 years have individuated sphingolipids not only as structural components of biological membranes but also as critical regulators of key biological processes, including cell survival. Ceramide, formed by catabolism of sphingomyelin (SM) and other complex sphingolipids, is a strong inducer of apoptotic pathway, whereas sphingosine 1-phosphate (S1P), generated by cleavage of ceramide to sphingosine and phosphorylation catalyzed by two distinct sphingosine kinase (SK) enzymes, stimulates cell survival. Interestingly S1P, by acting as intracellular mediator or as ligand of a family of five distinct S1P receptors (S1P1–S1P5), is a very powerful bioactive sphingolipid, capable of triggering also other diverse cellular responses such as cell migration, proliferation and differentiation, and is critically involved in the development and homeostasis of several organs and tissues. Although new interesting data have become available, the information on S1P pathway and other sphingolipids in the biology of the inner ear is limited. Nonetheless, there are several lines of evidence implicating these signaling molecules during neurogenesis in other cell populations. In this review, we discuss the role of S1P during inner ear development, also as guidance for future studies.
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Affiliation(s)
- Ricardo Romero-Guevara
- Department Scienze Biomediche Sperimentali e Cliniche "Mario Serio", University of Florence Firenze, Italy
| | - Francesca Cencetti
- Department Scienze Biomediche Sperimentali e Cliniche "Mario Serio", University of Florence Firenze, Italy
| | - Chiara Donati
- Department Scienze Biomediche Sperimentali e Cliniche "Mario Serio", University of Florence Firenze, Italy
| | - Paola Bruni
- Department Scienze Biomediche Sperimentali e Cliniche "Mario Serio", University of Florence Firenze, Italy
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10
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Comparative expression analysis of POU4F1, POU4F2 and ISL1 in developing mouse cochleovestibular ganglion neurons. Gene Expr Patterns 2014; 15:31-7. [PMID: 24709358 DOI: 10.1016/j.gep.2014.03.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Revised: 03/10/2014] [Accepted: 03/13/2014] [Indexed: 12/26/2022]
Abstract
POU-homeodomain and LIM-homeodomain transcription factors are expressed in developing projection neurons within retina, inner ear, dorsal root ganglion, and trigeminal ganglion, and play synergistic roles in their differentiation and survival. Here, using immunohistochemistry, we present a comparative analysis of the spatiotemporal expression pattern of POU4F1, POU4F2, and ISL1 during the development of cochleovestibular ganglion (CVG) neurons in mouse inner ear. At early stages, when otic neurons are first detected in the otic epithelium (OE) and migrate into periotic mesenchyme to form the CVG, POU4F1 and ISL1 are co-expressed in a majority of the delaminated CVG neurons, which are marked by NEUROD1 expression, but POU4F1 is absent in the otic epithelium. The onset of POU4F2 expression starts after that of POU4F1 and ISL1, and is observed in the NEUROD1-negative, post-mitotic CVG neurons. When the CVG neurons innervate the vestibular and cochlear sensory organs, the expression of POU4F1, POU4F2, and ISL1 continues in both vestibular and spiral ganglion cells. Later in development, POU4F1 expression becomes down-regulated in a majority of spiral ganglion (SG) neurons and more neurons express POU4F2 expression while ISL1 expression is maintained. The differential as well as overlapping expression of POU4F1, POU4F2, and ISL1 combined with previous studies suggests possible functional interaction and regulatory relationship of these transcription factors in the development of inner ear neurons.
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11
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Luo XJ, Deng M, Xie X, Huang L, Wang H, Jiang L, Liang G, Hu F, Tieu R, Chen R, Gan L. GATA3 controls the specification of prosensory domain and neuronal survival in the mouse cochlea. Hum Mol Genet 2013; 22:3609-23. [PMID: 23666531 DOI: 10.1093/hmg/ddt212] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
HDR syndrome (also known as Barakat syndrome) is a developmental disorder characterized by hypoparathyroidism, sensorineural deafness and renal disease. Although genetic mapping and subsequent functional studies indicate that GATA3 haplo-insufficiency causes human HDR syndrome, the role of Gata3 in sensorineural deafness and auditory system development is largely unknown. In this study, we show that Gata3 is continuously expressed in the developing mouse inner ear. Conditional knockout of Gata3 in the developing inner ear disrupts the morphogenesis of mouse inner ear, resulting in a disorganized and shortened cochlear duct with significant fewer hair cells and supporting cells. Loss of Gata3 function leads to the failure in the specification of prosensory domain and subsequently, to increased cell death in the cochlear duct. Moreover, though the initial generation of cochleovestibular ganglion (CVG) cells is not affected in Gata3-null mice, spiral ganglion neurons (SGNs) are nearly depleted due to apoptosis. Our results demonstrate the essential role of Gata3 in specifying the prosensory domain in the cochlea and in regulating the survival of SGNs, thus identifying a molecular mechanism underlying human HDR syndrome.
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Affiliation(s)
- Xiong-jian Luo
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, Zhejiang, China
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12
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Abstract
Spiral ganglion neurons (SGNs) play a key role in hearing by rapidly and faithfully transmitting signals from the cochlea to the brain. Identification of the transcriptional networks that ensure the proper specification and wiring of SGNs during development will lay the foundation for efforts to rewire a damaged cochlea. Here, we show that the transcription factor Gata3, which is expressed in SGNs throughout their development, is essential for formation of the intricately patterned connections in the cochlea. We generated conditional knock-out mice in which Gata3 is deleted after SGNs are specified. Cochlear wiring is severely disrupted in these animals, with premature extension of neurites that follow highly abnormal trajectories toward their targets, as shown using in vitro neurite outgrowth assays together with time-lapse imaging of whole embryonic cochleae. Expression profiling of mutant neurons revealed a broad shift in gene expression toward a more differentiated state, concomitant with minor changes in SGN identity. Thus, Gata3 appears to serve as an "intermediate regulator" that guides SGNs through differentiation and preserves the auditory fate. As the first auditory-specific regulator of SGN development, Gata3 provides a useful molecular entry point for efforts to engineer SGNs for the restoration of hearing.
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