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Feng Y, Zhang J, Li Y, Chen G, Zhang X, Ning G, Wu S. Inhibition of Pi4kb activity causes malformation of vestibular apparatus in zebrafish by downregulating hey1. Gene 2024; 898:148105. [PMID: 38135256 DOI: 10.1016/j.gene.2023.148105] [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: 09/25/2023] [Revised: 12/17/2023] [Accepted: 12/19/2023] [Indexed: 12/24/2023]
Abstract
Phosphatidylinositol 4 kinase-β (PI4KB) plays critical roles in human genetic diseases. In zebrafish, Pi4kb is strongly expressed in hair cells (HCs), which are necessary for detecting sound vibrations, head movements, and water motion. However, the role of PI4KB in HC or semicircular canal development is unclear. Herein, we report that pi4kb morphants exhibit insensitivity to sound stimulation and abnormal morphological vestibular organs, including cilium loss in HCs of the cristae and semicircular canal malformation. As bone morphogenetic protein (BMP) signaling is associated with HC and semicircular canal development, we analyzed the expression of BMP-related genes; the phosphorylated Smad1/5/9 (p-Smad1/5/9) expression was markedly reduced in otic HCs. RNA-sequencing data indicated that the transcriptional levels of BMP membrane receptor 2 (bmpr2a and bmpr2b) and hes-related family of bHLH transcription factors with YRPW motif 1 (hey1), a direct downstream target gene of p-Smad, were significantly reduced in the pi4kb morphants, as verified using quantitative reverse transcription-polymerase chain reaction and in situ hybridization. Co-injection of hey1 mRNA and pi4kb morpholino notably recovered vestibular apparatus development, including the number and length of cilia in HCs of the cristae and semicircular canal formation. Collectively, these results suggest that Pi4kb is involved in vestibular apparatus development in zebrafish by regulating BMP membrane receptor 2 and p-Smad1/5/9 levels, thereby affecting the transcriptional activation of the target gene hey1. This study sheds light on the interaction between Pi4kb and the BMP-Hey1 signaling axis, which is critical for HC and semicircular canal formation.
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Affiliation(s)
- Yufei Feng
- Life Science and Technology School, Lingnan Normal University, Zhanjiang, Guangdong, China
| | - Jiaqi Zhang
- Life Science and Technology School, Lingnan Normal University, Zhanjiang, Guangdong, China; Department of Physiology, School of Basic Medical Sciences, Harbin Medical University, Harbin, HeilongJiang, China
| | - Yuzhen Li
- Life Science and Technology School, Lingnan Normal University, Zhanjiang, Guangdong, China
| | - Gengrong Chen
- Life Science and Technology School, Lingnan Normal University, Zhanjiang, Guangdong, China
| | - Xiaoting Zhang
- Life Science and Technology School, Lingnan Normal University, Zhanjiang, Guangdong, China
| | - Guozhu Ning
- Affiliated Hospital of Guangdong Medical University & Zhanjiang Key Laboratory of Zebrafish Model for Development and Disease, Guangdong Medical University, Zhanjiang, Guangdong, China.
| | - Shuilong Wu
- Zhanjiang Institute of Clinical Medicine, Central People's Hospital of Zhanjiang, Zhanjiang, Guangdong, China.
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Sun L, Ping L, Gao R, Zhang B, Chen X. lmo4a Contributes to Zebrafish Inner Ear and Vestibular Development via Regulation of the Bmp Pathway. Genes (Basel) 2023; 14:1371. [PMID: 37510276 PMCID: PMC10378989 DOI: 10.3390/genes14071371] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 06/13/2023] [Accepted: 06/27/2023] [Indexed: 07/30/2023] Open
Abstract
BACKGROUND In vertebrates, the development of the inner ear is a delicate process, whereas its relating molecular pathways are still poorly understood. LMO4, an LIM domain-only transcriptional regulator, is drawing an increasing amount of interest for its multiple roles regarding human embryonic development and the modulation of ototoxic side effects of cisplatin including cochlear apoptosis and hearing loss. The aim of the present study is to further explore the role of lmo4a in zebrafish inner ear development and thus explore its functional role. METHODS The Spatial Transcript Omics DataBase was referred to in order to evaluate the expression of lmo4a during the first 24 h of zebrafish development. In situ hybridization was applied to validate and extend the expression profile of lmo4a to 3 days post-fertilization. The morpholino (MO) knockdown and CRISPR/Cas9 knockout (KO) of lmo4a was applied. Morphological analyses of otic vesical, hair cells, statoacoustic ganglion and semicircular canals were conducted. The swimming pattern of lmo4a KO and MO zebrafish was tracked. In situ hybridization was further applied to verify the expression of genes of the related pathways. Rescue of the phenotype was attempted by blockage of the bmp pathway via heat shock and injection of Dorsomorphin. RESULTS lmo4a is constitutively expressed in the otic placode and otic vesicle during the early stages of zebrafish development. Knockdown and knockout of lmo4a both induced smaller otocysts, less hair cells, immature statoacoustic ganglion and malformed semicircular canals. Abnormal swimming patterns could be observed in both lmo4a MO and KO zebrafish. eya1 in preplacodal ectoderm patterning was downregulated. bmp2 and bmp4 expressions were found to be upregulated and extended in lmo4a morphants, and blockage of the Bmp pathway partially rescued the vestibular defects. CONCLUSIONS We concluded that lmo4a holds a regulative effect on the Bmp pathway and is required for the normal development of zebrafish inner ear. Our study pointed out the conservatism of LMO4 in inner ear development between mammals and zebrafish as well as shed more light on the molecular mechanisms behind it. Further research is needed to distinguish the relationships between lmo4 and the Bmp pathway, which may lead to diagnostic and therapeutic approaches towards human inner ear malformation.
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Affiliation(s)
- Le Sun
- Department of Otolaryngology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, #1 Shuaifuyuan, Dongcheng District, Beijing 100730, China;
| | - Lu Ping
- Chinese Academy of Medical Sciences and Peking Union Medical College, #9 Dongdan Santiao, Dongcheng District, Beijing 100050, China;
| | - Ruzhen Gao
- Department of Clinical Laboratory, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China;
| | - Bo Zhang
- Key Laboratory of Cell Proliferation and Differentiation of the Ministry of Education, College of Life Sciences, Peking University, Beijing 100871, China;
| | - Xiaowei Chen
- Department of Otolaryngology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, #1 Shuaifuyuan, Dongcheng District, Beijing 100730, China;
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3
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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: 1.0] [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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4
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Guglielmi L, Heliot C, Kumar S, Alexandrov Y, Gori I, Papaleonidopoulou F, Barrington C, East P, Economou AD, French PMW, McGinty J, Hill CS. Smad4 controls signaling robustness and morphogenesis by differentially contributing to the Nodal and BMP pathways. Nat Commun 2021; 12:6374. [PMID: 34737283 PMCID: PMC8569018 DOI: 10.1038/s41467-021-26486-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 10/07/2021] [Indexed: 12/25/2022] Open
Abstract
The transcriptional effector SMAD4 is a core component of the TGF-β family signaling pathways. However, its role in vertebrate embryo development remains unresolved. To address this, we deleted Smad4 in zebrafish and investigated the consequences of this on signaling by the TGF-β family morphogens, BMPs and Nodal. We demonstrate that in the absence of Smad4, dorsal/ventral embryo patterning is disrupted due to the loss of BMP signaling. However, unexpectedly, Nodal signaling is maintained, but lacks robustness. This Smad4-independent Nodal signaling is sufficient for mesoderm specification, but not for optimal endoderm specification. Furthermore, using Optical Projection Tomography in combination with 3D embryo morphometry, we have generated a BMP morphospace and demonstrate that Smad4 mutants are morphologically indistinguishable from embryos in which BMP signaling has been genetically/pharmacologically perturbed. Smad4 is thus differentially required for signaling by different TGF-β family ligands, which has implications for diseases where Smad4 is mutated or deleted.
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Affiliation(s)
- Luca Guglielmi
- Developmental Signalling Laboratory, The Francis Crick Institute, London, NW1 1AT, UK
| | - Claire Heliot
- Developmental Signalling Laboratory, The Francis Crick Institute, London, NW1 1AT, UK
| | - Sunil Kumar
- Advanced Light Microscopy, The Francis Crick Institute, London, NW1 1AT, UK
| | - Yuriy Alexandrov
- Advanced Light Microscopy, The Francis Crick Institute, London, NW1 1AT, UK
| | - Ilaria Gori
- Developmental Signalling Laboratory, The Francis Crick Institute, London, NW1 1AT, UK
| | | | - Christopher Barrington
- Bioinformatics and Biostatistics Facility, The Francis Crick Institute, London, NW1 1AT, UK
| | - Philip East
- Bioinformatics and Biostatistics Facility, The Francis Crick Institute, London, NW1 1AT, UK
| | - Andrew D Economou
- Developmental Signalling Laboratory, The Francis Crick Institute, London, NW1 1AT, UK
| | - Paul M W French
- Department of Physics, Imperial College London, SW7 2AZ, London, UK
| | - James McGinty
- Department of Physics, Imperial College London, SW7 2AZ, London, UK
| | - Caroline S Hill
- Developmental Signalling Laboratory, The Francis Crick Institute, London, NW1 1AT, UK.
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5
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Mackowetzky K, Yoon KH, Mackowetzky EJ, Waskiewicz AJ. Development and evolution of the vestibular apparatuses of the inner ear. J Anat 2021; 239:801-828. [PMID: 34047378 PMCID: PMC8450482 DOI: 10.1111/joa.13459] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 04/07/2021] [Accepted: 05/06/2021] [Indexed: 12/16/2022] Open
Abstract
The vertebrate inner ear is a labyrinthine sensory organ responsible for perceiving sound and body motion. While a great deal of research has been invested in understanding the auditory system, a growing body of work has begun to delineate the complex developmental program behind the apparatuses of the inner ear involved with vestibular function. These animal studies have helped identify genes involved in inner ear development and model syndromes known to include vestibular dysfunction, paving the way for generating treatments for people suffering from these disorders. This review will provide an overview of known inner ear anatomy and function and summarize the exciting discoveries behind inner ear development and the evolution of its vestibular apparatuses.
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Affiliation(s)
- Kacey Mackowetzky
- Department of Biological SciencesUniversity of AlbertaEdmontonAlbertaCanada
| | - Kevin H. Yoon
- Department of Biological SciencesUniversity of AlbertaEdmontonAlbertaCanada
| | | | - Andrew J. Waskiewicz
- Department of Biological SciencesUniversity of AlbertaEdmontonAlbertaCanada
- Women & Children’s Health Research InstituteUniversity of AlbertaEdmontonAlbertaCanada
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6
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Wen J, Song J, Bai Y, Liu Y, Cai X, Mei L, Ma L, He C, Feng Y. A Model of Waardenburg Syndrome Using Patient-Derived iPSCs With a SOX10 Mutation Displays Compromised Maturation and Function of the Neural Crest That Involves Inner Ear Development. Front Cell Dev Biol 2021; 9:720858. [PMID: 34426786 PMCID: PMC8379019 DOI: 10.3389/fcell.2021.720858] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Accepted: 07/22/2021] [Indexed: 12/20/2022] Open
Abstract
Waardenburg syndrome (WS) is an autosomal dominant inherited disorder that is characterized by sensorineural hearing loss and abnormal pigmentation. SOX10 is one of its main pathogenicity genes. The generation of patient-specific induced pluripotent stem cells (iPSCs) is an efficient means to investigate the mechanisms of inherited human disease. In our work, we set up an iPSC line derived from a WS patient with SOX10 mutation and differentiated into neural crest cells (NCCs), a key cell type involved in inner ear development. Compared with control-derived iPSCs, the SOX10 mutant iPSCs showed significantly decreased efficiency of development and differentiation potential at the stage of NCCs. After that, we carried out high-throughput RNA-seq and evaluated the transcriptional misregulation at every stage. Transcriptome analysis of differentiated NCCs showed widespread gene expression alterations, and the differentially expressed genes (DEGs) were enriched in gene ontology terms of neuron migration, skeletal system development, and multicellular organism development, indicating that SOX10 has a pivotal part in the differentiation of NCCs. It's worth noting that, a significant enrichment among the nominal DEGs for genes implicated in inner ear development was found, as well as several genes connected to the inner ear morphogenesis. Based on the protein-protein interaction network, we chose four candidate genes that could be regulated by SOX10 in inner ear development, namely, BMP2, LGR5, GBX2, and GATA3. In conclusion, SOX10 deficiency in this WS subject had a significant impact on the gene expression patterns throughout NCC development in the iPSC model. The DEGs most significantly enriched in inner ear development and morphogenesis may assist in identifying the underlying basis for the inner ear malformation in subjects with WS.
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Affiliation(s)
- Jie Wen
- Department of Otorhinolaryngology, Xiangya Hospital Central South University, Changsha, China.,Province Key Laboratory of Otolaryngology Critical Diseases, Changsha, China.,Department of Geriatrics, National Clinical Research Centre for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
| | - Jian Song
- Department of Otorhinolaryngology, Xiangya Hospital Central South University, Changsha, China.,Province Key Laboratory of Otolaryngology Critical Diseases, Changsha, China.,Department of Geriatrics, National Clinical Research Centre for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
| | - Yijiang Bai
- Department of Otorhinolaryngology, Xiangya Hospital Central South University, Changsha, China.,Province Key Laboratory of Otolaryngology Critical Diseases, Changsha, China.,Department of Geriatrics, National Clinical Research Centre for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
| | - Yalan Liu
- Department of Otorhinolaryngology, Xiangya Hospital Central South University, Changsha, China.,Province Key Laboratory of Otolaryngology Critical Diseases, Changsha, China.,Department of Geriatrics, National Clinical Research Centre for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
| | - Xinzhang Cai
- Department of Otorhinolaryngology, Xiangya Hospital Central South University, Changsha, China.,Province Key Laboratory of Otolaryngology Critical Diseases, Changsha, China.,Department of Geriatrics, National Clinical Research Centre for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
| | - Lingyun Mei
- Department of Otorhinolaryngology, Xiangya Hospital Central South University, Changsha, China.,Province Key Laboratory of Otolaryngology Critical Diseases, Changsha, China.,Department of Geriatrics, National Clinical Research Centre for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
| | - Lu Ma
- Department of Otorhinolaryngology, The Affiliated Changsha Central Hospital, Hengyang Medical School, University of South China, Changsha, China
| | - Chufeng He
- Department of Otorhinolaryngology, Xiangya Hospital Central South University, Changsha, China.,Province Key Laboratory of Otolaryngology Critical Diseases, Changsha, China.,Department of Geriatrics, National Clinical Research Centre for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, China
| | - Yong Feng
- Department of Otorhinolaryngology, Xiangya Hospital Central South University, Changsha, China.,Department of Otorhinolaryngology, The Affiliated Changsha Central Hospital, Hengyang Medical School, University of South China, Changsha, China
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7
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Hwang CH, Keller J, Renner C, Ohta S, Wu DK. Genetic interactions support an inhibitory relationship between bone morphogenetic protein 2 and netrin 1 during semicircular canal formation. Development 2019; 146:dev.174748. [PMID: 30770380 PMCID: PMC6398446 DOI: 10.1242/dev.174748] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 01/18/2019] [Indexed: 12/16/2022]
Abstract
The semicircular canals of the mammalian inner ear are derived from epithelial pouches in which epithelial cells in the central region of each pouch undergo resorption, leaving behind the region at the rim to form a tube-shaped canal. Lack of proliferation at the rim and/or over-clearing of epithelial cells in the center of the pouch can obliterate canal formation. Otic-specific knockout of bone morphogenetic protein 2 (Bmp2) results in absence of all three semicircular canals; however, the common crus and ampullae housing the sensory tissue (crista) are intact. The lack of Bmp2 causes Ntn1 (which encodes netrin 1), which is required for canal resorption, to be ectopically expressed at the canal rim. Ectopic Ntn1 results in reduction of Dlx5 and Lmo4, which are required for rim formation. These phenotypes can be partially rescued by removing one allele of Ntn1 in the Bmp2 mutants, indicating that Bmp2 normally negatively regulates Ntn1 for canal formation. Additionally, non-resorption of the canal pouch in Ntn1−/− mutants is partially rescued by removing one allele of Bmp2. Thus, reciprocal inhibition between Bmp2 and netrin 1 is involved in canal formation of the vestibule. Summary:Bmp2-conditional mutant analyses support the hypothesis that presumptive crista induces canal genesis zone in the canal pouch to express Bmp2, which promotes canal formation by restricting Ntn1 expression to the resorption domain.
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Affiliation(s)
- Chan Ho Hwang
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Porter Neuroscience Research Center, Bethesda, MD 20892, USA
| | - James Keller
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Porter Neuroscience Research Center, Bethesda, MD 20892, USA
| | - Charles Renner
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Porter Neuroscience Research Center, Bethesda, MD 20892, USA
| | - Sho Ohta
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Porter Neuroscience Research Center, Bethesda, MD 20892, USA
| | - Doris K Wu
- National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Porter Neuroscience Research Center, Bethesda, MD 20892, USA
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8
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Tawfik KO, Leader BA, Walters ZA, Choo DI. Relative Preservation of Superior Semicircular Canal Architecture in CHARGE Syndrome. Otolaryngol Head Neck Surg 2019; 160:1095-1100. [PMID: 30667318 DOI: 10.1177/0194599818824306] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVES (1) Describe common patterns of semicircular canal (SCC) anomalies in CHARGE syndrome (CS) and (2) recognize that in CS, the architecture of the superior SCC may be relatively preserved. STUDY DESIGN This is a retrospective review of temporal bone imaging studies. SETTING Quaternary care center. SUBJECTS AND METHODS A sample of 37 patients with CS. All subjects met clinical diagnostic criteria for CS. The presence/absence of anomalies of the middle ear, mastoid, temporal bone venous anatomy, inner ear, and internal auditory canal was recorded. Anomalies of each SCC were considered separately and by severity (normal, dysplasia, aplasia). RESULTS Thirty-seven subjects (74 temporal bones) were reviewed. Thirty-four (92.0%) patients demonstrated bilateral SCC anomalies. Three (8.0%) had normal SCCs. In patients with SCC anomalies, all canals demonstrated bilateral abnormalities. Thirty-two (86.5%) patients had bilateral horizontal SCC aplasia. These 32 patients also demonstrated posterior SCC aplasia in at least 1 ear. Of 74 temporal bones, 37 (50.0%) had superior SCC dysplasia. All dysplastic superior SCCs showed preservation of the anterior limb. Complete superior SCC aplasia was found in 28 (37.8%) temporal bones. CONCLUSION SCC anomalies occur with high frequency in CS. Complete absence of the horizontal and posterior canals is typical and usually bilateral. By contrast, the superior SCC often demonstrates relative preservation of the anterior limb.
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Affiliation(s)
- Kareem O Tawfik
- 1 Division of Otolaryngology-Head & Neck Surgery, University of California, San Diego School of Medicine, San Diego, California, USA
| | - Brittany A Leader
- 2 Department of Otolaryngology-Head & Neck Surgery, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Zoe A Walters
- 3 University of Cincinnati College of Medicine, Cincinnati, Ohio, USA
| | - Daniel I Choo
- 2 Department of Otolaryngology-Head & Neck Surgery, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA.,4 Division of Pediatric Otolaryngology-Head & Neck Surgery, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
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9
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Inner Ear Otolith Asymmetry in Late-Larval Cichlid Fish (Oreochromis mossambicus, Perciformes) Showing Kinetotic Behaviour Under Diminished Gravity. Sci Rep 2017; 7:15630. [PMID: 29142237 PMCID: PMC5688164 DOI: 10.1038/s41598-017-15927-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 11/04/2017] [Indexed: 11/18/2022] Open
Abstract
The inner ears of all vertebrates are designed to perceive auditory and vestibular inputs. Although a tremendous diversity in the inner ear can be found even among bony fishes, the morphologies of the utricle and of the semicircular canals are rather conservative among vertebrates. Fish show kinetoses under reduced gravity (spinning movements and looping responses) and are regarded model organisms concerning the performance of the otolithic organs. Otoliths can be analysed easily because they are compact, in contrast to the otoconial masses of other vertebrates. Here, late-larval Oreochromis mossambicus were subjected to 0.0001 × g and 0.04 × g aboard a sounding rocket, their behaviour was observed and morphometrical analyses on otoliths were carried out. Fish swimming kinetotically at 0.0001 × g had a higher asymmetry of utricular otoliths (gravity perception) but not of saccular otoliths (hearing process) than specimens behaving normally at this gravity level (p = 0.0055). Also, asymmetries of lapilli in animals swimming normally at 0.0001 × g were lower than asymmetries in specimens swimming normally at 0.04 × g (p = 0.06). This supports the “otolith asymmetry hypothesis”, an explanation for the susceptibility to kinetosis, particularly concerning the utricular otoliths. It would be interesting to identify processes generating asymmetric otoliths, also in regard to human motion sickness.
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10
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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: 5.4] [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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11
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Tfap2a promotes specification and maturation of neurons in the inner ear through modulation of Bmp, Fgf and notch signaling. PLoS Genet 2015; 11:e1005037. [PMID: 25781991 PMCID: PMC4364372 DOI: 10.1371/journal.pgen.1005037] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 01/28/2015] [Indexed: 11/23/2022] Open
Abstract
Neurons of the statoacoustic ganglion (SAG) transmit auditory and vestibular information from the inner ear to the hindbrain. SAG neuroblasts originate in the floor of the otic vesicle. New neuroblasts soon delaminate and migrate towards the hindbrain while continuing to proliferate, a phase known as transit amplification. SAG cells eventually come to rest between the ear and hindbrain before terminally differentiating. Regulation of these events is only partially understood. Fgf initiates neuroblast specification within the ear. Subsequently, Fgf secreted by mature SAG neurons exceeds a maximum threshold, serving to terminate specification and delay maturation of transit-amplifying cells. Notch signaling also limits SAG development, but how it is coordinated with Fgf is unknown. Here we show that transcription factor Tfap2a coordinates multiple signaling pathways to promote neurogenesis in the zebrafish inner ear. In both zebrafish and chick, Tfap2a is expressed in a ventrolateral domain of the otic vesicle that includes neurogenic precursors. Functional studies were conducted in zebrafish. Loss of Tfap2a elevated Fgf and Notch signaling, thereby inhibiting SAG specification and slowing maturation of transit-amplifying cells. Conversely, overexpression of Tfap2a inhibited Fgf and Notch signaling, leading to excess and accelerated SAG production. However, most SAG neurons produced by Tfap2a overexpression died soon after maturation. Directly blocking either Fgf or Notch caused less dramatic acceleration of SAG development without neuronal death, whereas blocking both pathways mimicked all observed effects of Tfap2a overexpression, including apoptosis of mature neurons. Analysis of genetic mosaics showed that Tfap2a acts non-autonomously to inhibit Fgf. This led to the discovery that Tfap2a activates expression of Bmp7a, which in turn inhibits both Fgf and Notch signaling. Blocking Bmp signaling reversed the effects of overexpressing Tfap2a. Together, these data support a model in which Tfap2a, acting through Bmp7a, modulates Fgf and Notch signaling to control the duration, amount and speed of SAG neural development. Neurons of the statoacoustic ganglion (SAG) transmit impulses from the inner ear necessary for hearing and balance. SAG cells exhibit a complex pattern of development, regulation of which remains poorly understood. Here we show that transcription factor Tfap2a coordinates multiple cell signaling pathways needed to regulate the quantity and pace of SAG neuron production. SAG progenitors originate within the developing inner ear and then migrate out of the ear towards the hindbrain before forming mature neurons. We showed previously that Fgf initiates formation of SAG progenitors in the inner ear, but rising levels of Fgf signaling eventually terminate this process. Elevated Fgf also stimulates proliferation of SAG progenitors outside the ear and delays their maturation. Notch signaling is also known to limit SAG development. Tfap2a governs the strength of Fgf and Notch signaling by activating expression of Bmp7a, which inhibits Fgf and Notch. Together these signals stabilize the pool of SAG progenitors outside the ear by equalizing rates of maturation and proliferation. This balance is critical for sustained accumulation of SAG neurons during larval growth as well as regeneration following neural damage. These findings could inform development of stem cell therapies to correct auditory neuropathies in humans.
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12
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Fritzsch B, Pan N, Jahan I, Duncan JS, Kopecky BJ, Elliott KL, Kersigo J, Yang T. Evolution and development of the tetrapod auditory system: an organ of Corti-centric perspective. Evol Dev 2013; 15:63-79. [PMID: 23331918 DOI: 10.1111/ede.12015] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The tetrapod auditory system transmits sound through the outer and middle ear to the organ of Corti or other sound pressure receivers of the inner ear where specialized hair cells translate vibrations of the basilar membrane into electrical potential changes that are conducted by the spiral ganglion neurons to the auditory nuclei. In other systems, notably the vertebrate limb, a detailed connection between the evolutionary variations in adaptive morphology and the underlying alterations in the genetic basis of development has been partially elucidated. In this review, we attempt to correlate evolutionary and partially characterized molecular data into a cohesive perspective of the evolution of the mammalian organ of Corti out of the tetrapod basilar papilla. We propose a stepwise, molecularly partially characterized transformation of the ancestral, vestibular developmental program of the vertebrate ear. This review provides a framework to decipher both discrete steps in development and the evolution of unique functional adaptations of the auditory system. The combined analysis of evolution and development establishes a powerful cross-correlation where conclusions derived from either approach become more meaningful in a larger context which is not possible through exclusively evolution or development centered perspectives. Selection may explain the survival of the fittest auditory system, but only developmental genetics can explain the arrival of the fittest auditory system. [Modified after (Wagner 2011)].
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Affiliation(s)
- Bernd Fritzsch
- Department of Biology, University of Iowa, CLAS, 143 BB, Iowa City, IA, 52242, USA. bernd‐
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Rakowiecki S, Epstein DJ. Divergent roles for Wnt/β-catenin signaling in epithelial maintenance and breakdown during semicircular canal formation. Development 2013; 140:1730-9. [PMID: 23487315 DOI: 10.1242/dev.092882] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The morphogenetic program that shapes the three semicircular canals (SSCs) must be executed with extreme precision to satisfy their complex vestibular function. The SSCs emerge from epithelial outgrowths of the dorsal otocyst, the central regions of which fuse and resorb to leave three fluid-filled canals. The Wnt/β-catenin signaling pathway is active at multiple stages of otic development, including during vestibular morphogenesis. How Wnt/β-catenin functionally integrates with other signaling pathways to sculpt the SSCs and their sensory patches is unknown. We used a genetic strategy to spatiotemporally modulate canonical Wnt signaling activity during SSC development in mice. Our findings demonstrate that Wnt/β-catenin signaling functions in a multifaceted manner during SSC formation. In the early phase, Wnt/β-catenin signaling is required to preserve the epithelial integrity of the vertical canal pouch perimeter (presumptive anterior and posterior SSCs) by establishing a sensory-dependent signaling relay that maintains expression of Dlx5 and opposes expression of the fusion plate marker netrin 1. Without this Wnt signaling activity the sensory to non-sensory signaling cascade fails to be activated, resulting in loss of vestibular hair and support cells and the anterior and posterior SSCs. In the later phase, Wnt/β-catenin signaling becomes restricted to the fusion plate where it facilitates the timely resorption of this tissue. Mosaic recombination of β-catenin in small clusters of canal pouch cells prevents their resorption, causing instead the formation of ectopic SSCs. Together, these disparate functions of the Wnt/β-catenin pathway in epithelial maintenance and resorption help regulate the size, shape and number of SSCs.
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Affiliation(s)
- Staci Rakowiecki
- Department of Genetics, University of Pennsylvania, Philadelphia, PA 19104, USA
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Wise SB, Stock DW. bmp2b and bmp4 are dispensable for zebrafish tooth development. Dev Dyn 2011; 239:2534-46. [PMID: 21038444 DOI: 10.1002/dvdy.22411] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Bone morphogenetic protein (Bmp) signaling has been shown to play important roles in tooth development at virtually all stages from initiation to hard tissue formation. The specific ligands involved in these processes have not been directly tested by loss-of-function experiments, however. We used morpholino antisense oligonucleotides and mutant analysis in the zebrafish to reduce or eliminate the function of bmp2b and bmp4, two ligands known to be expressed in zebrafish teeth and whose mammalian orthologs are thought to play important roles in tooth development. Surprisingly, we found that elimination of function of these two genes singly and in combination did not prevent the formation of mature, attached teeth. The mostly likely explanation for this result is functional redundancy with other Bmp ligands, which may differ between the zebrafish and the mouse.
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Affiliation(s)
- Sarah B Wise
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, Colorado 80309-0449, USA
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BMP signaling is necessary for patterning the sensory and nonsensory regions of the developing mammalian cochlea. J Neurosci 2010; 30:15044-51. [PMID: 21068310 DOI: 10.1523/jneurosci.3547-10.2010] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The mammalian inner ear detects sound with the organ of Corti, an intricately patterned region of the cochlea in which one row of inner hair cells and three rows of outer hair cells are surrounded by specialized supporting cells. The organ of Corti derives from a prosensory domain that runs the length of the cochlear duct and is bounded by two nonsensory domains, Kölliker's organ on the neural side and the outer sulcus on the abneural side. Although much progress has been made in identifying the signals regulating organ of Corti induction and differentiation, less is known about the mechanisms that establish sensory and nonsensory territories in the cochlear duct. Here, we show that a gradient of bone morphogenetic protein (BMP) signaling is established in the abneural-neural axis of the cochlea. Analysis of compound mutants of Alk3/6 type I BMP receptors shows that BMP signaling is necessary for specification of the prosensory domain destined to form the organ of Corti. Reduction of BMP signaling in Alk3/6 compound mutants eliminates both the future outer sulcus and the prosensory domain, with all cells expressing markers of Kölliker's organ. BMP4 upregulates markers of the future outer sulcus and downregulates marker genes of Kölliker's organ in cochlear organ cultures in a dose-dependent manner. Our results suggest BMP signaling is required for patterning sensory and nonsensory tissue in the mammalian cochlea.
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Li Y, Laue K, Temtamy S, Aglan M, Kotan LD, Yigit G, Canan H, Pawlik B, Nürnberg G, Wakeling EL, Quarrell OW, Baessmann I, Lanktree MB, Yilmaz M, Hegele RA, Amr K, May KW, Nürnberg P, Topaloglu AK, Hammerschmidt M, Wollnik B. Temtamy preaxial brachydactyly syndrome is caused by loss-of-function mutations in chondroitin synthase 1, a potential target of BMP signaling. Am J Hum Genet 2010; 87:757-67. [PMID: 21129728 DOI: 10.1016/j.ajhg.2010.10.003] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2010] [Revised: 10/03/2010] [Accepted: 10/07/2010] [Indexed: 01/09/2023] Open
Abstract
Altered Bone Morphogenetic Protein (BMP) signaling leads to multiple developmental defects, including brachydactyly and deafness. Here we identify chondroitin synthase 1 (CHSY1) as a potential mediator of BMP effects. We show that loss of human CHSY1 function causes autosomal-recessive Temtamy preaxial brachydactyly syndrome (TPBS), mainly characterized by limb malformations, short stature, and hearing loss. After mapping the TPBS locus to chromosome 15q26-qterm, we identified causative mutations in five consanguineous TPBS families. In zebrafish, antisense-mediated chsy1 knockdown causes defects in multiple developmental processes, some of which are likely to also be causative in the etiology of TPBS. In the inner ears of zebrafish larvae, chsy1 is expressed similarly to the BMP inhibitor dan and in a complementary fashion to bmp2b. Furthermore, unrestricted Bmp2b signaling or loss of Dan activity leads to reduced chsy1 expression and, during epithelial morphogenesis, defects similar to those that occur upon Chsy1 inactivation, indicating that Bmp signaling affects inner-ear development by repressing chsy1. In addition, we obtained strikingly similar zebrafish phenotypes after chsy1 overexpression, which might explain why, in humans, brachydactyly can be caused by mutations leading either to loss or to gain of BMP signaling.
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Affiliation(s)
- Yun Li
- Center for Molecular Medicine Cologne, University of Cologne, Germany
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BMP/SMAD signaling regulates the cell behaviors that drive the initial dorsal-specific regional morphogenesis of the otocyst. Dev Biol 2010; 347:369-81. [PMID: 20837004 DOI: 10.1016/j.ydbio.2010.09.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2010] [Revised: 09/02/2010] [Accepted: 09/02/2010] [Indexed: 12/20/2022]
Abstract
During development of the otocyst, regional morphogenesis establishes a dorsal vestibular chamber and a ventral auditory chamber, which collectively constitute the membranous labyrinth of the inner ear. We identified the earliest morphogenetic event heralding the formation of the vestibular chamber, a rapid thinning and expansion of the dorsolateral wall of the otocyst, and showed that this process is generated by changes in otocyst cell shape from columnar to squamous, as opposed to changes in other cell behaviors, such as localized changes in cell proliferation or cell death. Moreover, we showed that thinning and expansion of the dorsolateral otocyst is regulated by BMP/SMAD signaling, which is both sufficient and necessary for localized thinning and expansion. Finally, we showed that BMP/SMAD signaling causes fragmentation of E-cadherin in the dorsolateral otocyst, occurring concomitantly with cell shape change, suggesting that BMP/SMAD signaling regulates cell-cell adhesion during the initial morphogenesis of the otocyst epithelium. Collectively, our results show that BMP signaling via SMADs regulates the cell behaviors that drive the initial dorsal-specific morphogenesis of the otocyst, providing new information about how regional morphogenesis of a complex organ rudiment, the developing membranous labyrinth, is initiated.
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Abbas L, Whitfield TT. The zebrafish inner ear. ACTA ACUST UNITED AC 2010. [DOI: 10.1016/s1546-5098(10)02904-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
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Hwang CH, Simeone A, Lai E, Wu DK. Foxg1is required for proper separation and formation of sensory cristae during inner ear development. Dev Dyn 2009; 238:2725-34. [PMID: 19842177 DOI: 10.1002/dvdy.22111] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Chan Ho Hwang
- Lab of Molecular Biology, National Institute on Deafness and Other Communication Disorders, Rockville, Maryland 20850, USA
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