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Gao J, Skidmore JM, Cimerman J, Ritter KE, Qiu J, Wilson LMQ, Raphael Y, Kwan KY, Martin DM. CHD7 and SOX2 act in a common gene regulatory network during mammalian semicircular canal and cochlear development. Proc Natl Acad Sci U S A 2024; 121:e2311720121. [PMID: 38408234 DOI: 10.1073/pnas.2311720121] [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: 07/29/2023] [Accepted: 01/19/2024] [Indexed: 02/28/2024] Open
Abstract
Inner ear morphogenesis requires tightly regulated epigenetic and transcriptional control of gene expression. CHD7, an ATP-dependent chromodomain helicase DNA-binding protein, and SOX2, an SRY-related HMG box pioneer transcription factor, are known to contribute to vestibular and auditory system development, but their genetic interactions in the ear have not been explored. Here, we analyzed inner ear development and the transcriptional regulatory landscapes in mice with variable dosages of Chd7 and/or Sox2. We show that combined haploinsufficiency for Chd7 and Sox2 results in reduced otic cell proliferation, severe malformations of semicircular canals, and shortened cochleae with ectopic hair cells. Examination of mice with conditional, inducible Chd7 loss by Sox2CreER reveals a critical period (~E9.5) of susceptibility in the inner ear to combined Chd7 and Sox2 loss. Data from genome-wide RNA-sequencing and CUT&Tag studies in the otocyst show that CHD7 regulates Sox2 expression and acts early in a gene regulatory network to control expression of key otic patterning genes, including Pax2 and Otx2. CHD7 and SOX2 directly bind independently and cooperatively at transcription start sites and enhancers to regulate otic progenitor cell gene expression. Together, our findings reveal essential roles for Chd7 and Sox2 in early inner ear development and may be applicable for syndromic and other forms of hearing or balance disorders.
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Affiliation(s)
- Jingxia Gao
- Department of Pediatrics, The University of Michigan, Ann Arbor, MI 48109
| | | | - Jelka Cimerman
- Department of Pediatrics, The University of Michigan, Ann Arbor, MI 48109
| | - K Elaine Ritter
- Department of Pediatrics, The University of Michigan, Ann Arbor, MI 48109
| | - Jingyun Qiu
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854
- Keck Center for Collaborative Neuroscience, Stem Cell Research Center, Rutgers University, Piscataway, NJ 08854
| | - Lindsey M Q Wilson
- Medical Scientist Training Program, The University of Michigan, Ann Arbor, MI 48109
| | - Yehoash Raphael
- Department of Otolaryngology-Head and Neck Surgery, The University of Michigan, Ann Arbor, MI 48109
| | - Kelvin Y Kwan
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, NJ 08854
- Keck Center for Collaborative Neuroscience, Stem Cell Research Center, Rutgers University, Piscataway, NJ 08854
| | - Donna M Martin
- Department of Pediatrics, The University of Michigan, Ann Arbor, MI 48109
- Department of Human Genetics, The University of Michigan, Ann Arbor, MI 48109
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2
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Roux I, Fenollar-Ferrer C, Lee HJ, Chattaraj P, Lopez IA, Han K, Honda K, Brewer CC, Butman JA, Morell RJ, Martin DM, Griffith AJ. CHD7 variants associated with hearing loss and enlargement of the vestibular aqueduct. Hum Genet 2023; 142:1499-1517. [PMID: 37668839 PMCID: PMC10511616 DOI: 10.1007/s00439-023-02581-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2023] [Accepted: 06/20/2023] [Indexed: 09/06/2023]
Abstract
Enlargement of the endolymphatic sac, duct, and vestibular aqueduct (EVA) is the most common inner ear malformation identified in patients with sensorineural hearing loss. EVA is associated with pathogenic variants in SLC26A4. However, in European-Caucasian populations, about 50% of patients with EVA carry no pathogenic alleles of SLC26A4. We tested for the presence of variants in CHD7, a gene known to be associated with CHARGE syndrome, Kallmann syndrome, and hypogonadotropic hypogonadism, in a cohort of 34 families with EVA subjects without pathogenic alleles of SLC26A4. In two families, NM_017780.4: c.3553A > G [p.(Met1185Val)] and c.5390G > C [p.(Gly1797Ala)] were detected as monoallelic CHD7 variants in patients with EVA. At least one subject from each family had additional signs or potential signs of CHARGE syndrome but did not meet diagnostic criteria for CHARGE. In silico modeling of these two missense substitutions predicted detrimental effects upon CHD7 protein structure. Consistent with a role of CHD7 in this tissue, Chd7 transcript and protein were detected in all epithelial cells of the endolymphatic duct and sac of the developing mouse inner ear. These results suggest that some CHD7 variants can cause nonsyndromic hearing loss and EVA. CHD7 should be included in DNA sequence analyses to detect pathogenic variants in EVA patients. Chd7 expression and mutant phenotype data in mice suggest that CHD7 contributes to the formation or function of the endolymphatic sac and duct.
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Affiliation(s)
- Isabelle Roux
- Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders (NIDCD), National Institutes of Health (NIH), Bethesda, MD, 20892, USA.
| | - Cristina Fenollar-Ferrer
- Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders (NIDCD), National Institutes of Health (NIH), Bethesda, MD, 20892, USA
- Laboratory of Molecular Genetics, NIDCD, NIH, Bethesda, MD, 20892, USA
| | - Hyun Jae Lee
- Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders (NIDCD), National Institutes of Health (NIH), Bethesda, MD, 20892, USA
| | - Parna Chattaraj
- Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders (NIDCD), National Institutes of Health (NIH), Bethesda, MD, 20892, USA
| | - Ivan A Lopez
- The NIDCD National Temporal Laboratory at UCLA, Department of Head and Neck Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, 90095, USA
| | - Kyungreem Han
- Laboratory of Membrane Biophysics, NHLBI, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Keiji Honda
- Department of Otorhinolaryngology, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, Japan
| | - Carmen C Brewer
- Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders (NIDCD), National Institutes of Health (NIH), Bethesda, MD, 20892, USA
| | - John A Butman
- Radiology and Imaging Sciences, Clinical Center, NIH, Bethesda, MD, 20892, USA
| | - Robert J Morell
- Genomics and Computational Biology Core, NIDCD, NIH, Bethesda, MD, 20892, USA
| | - Donna M Martin
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, USA
- Department of Pediatrics, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Andrew J Griffith
- Otolaryngology Branch, National Institute on Deafness and Other Communication Disorders (NIDCD), National Institutes of Health (NIH), Bethesda, MD, 20892, USA
- Department of Otolaryngology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, 38163, USA
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3
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Shi L, Wang Z, Li Y, Song Z, Yin W, Hu B. Deletion of the chd7 Hinders Oligodendrocyte Progenitor Cell Development and Myelination in Zebrafish. Int J Mol Sci 2023; 24:13535. [PMID: 37686337 PMCID: PMC10488005 DOI: 10.3390/ijms241713535] [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: 08/04/2023] [Revised: 08/24/2023] [Accepted: 08/25/2023] [Indexed: 09/10/2023] Open
Abstract
CHD7, an encoding ATP-dependent chromodomain helicase DNA-binding protein 7, has been identified as the causative gene involved in CHARGE syndrome (Coloboma of the eye, Heart defects, Atresia choanae, Retardation of growth and/or development, Genital abnormalities and Ear abnormalities). Although studies in rodent models have expanded our understanding of CHD7, its role in oligodendrocyte (OL) differentiation and myelination in zebrafish is still unclear. In this study, we generated a chd7-knockout strain with CRISPR/Cas9 in zebrafish. We observed that knockout (KO) of chd7 intensely impeded the oligodendrocyte progenitor cells' (OPCs) migration and myelin formation due to massive expression of chd7 in oilg2+ cells, which might provoke upregulation of the MAPK signal pathway. Thus, our study demonstrates that chd7 is critical to oligodendrocyte migration and myelination during early development in zebrafish and describes a mechanism potentially associated with CHARGE syndrome.
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Affiliation(s)
- Lingyu Shi
- Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China; (L.S.)
| | - Zongyi Wang
- Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China; (L.S.)
| | - Yujiao Li
- Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China; (L.S.)
| | - Zheng Song
- Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China; (L.S.)
| | - Wu Yin
- Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230001, China
| | - Bing Hu
- Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China; (L.S.)
- Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230001, China
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4
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Lewis MA, Juliano A, Robson C, Clement E, Nash R, Rajput K, D'Arco F. The spectrum of cochlear malformations in CHARGE syndrome and insights into the role of the CHD7 gene during embryogenesis of the inner ear. Neuroradiology 2023; 65:819-834. [PMID: 36715725 DOI: 10.1007/s00234-023-03118-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 01/09/2023] [Indexed: 01/31/2023]
Abstract
PURPOSE We reviewed the genotypes and the imaging appearances of cochleae in CHARGE patients from two large tertiary centres and analysed the observed cochlear anomalies, providing detailed anatomical description and a grading system. The goal was to gain insight into the spectrum of cochlear anomalies in CHARGE syndrome, and thus, in the role of the CHD7 gene in otic vesicle development. METHODS We retrospectively reviewed CT and/or MR imaging of CHARGE patients referred to our institutions between 2005 and 2022. Cochlear morphology was analysed and, when abnormal, divided into 3 groups in order of progressive severity. Other radiological findings in the temporal bone were also recorded. Comparison with the existing classification system of cochlear malformation was also attempted. RESULTS Cochlear morphology in our CHARGE cohort ranged from normal to extreme hypoplasia. The most common phenotype was cochlear hypoplasia in which the basal turn was relatively preserved, and the upper turns were underdeveloped. All patients in the cohort had absent or markedly hypoplastic semicircular canals and small, misshapen vestibules. Aside from a stenotic cochlear aperture (fossette) being associated with a hypoplastic or absent cochlear nerve, there was no consistent relationship between cochlear nerve status (normal, hypoplasia, or aplasia) and cochlear morphology. CONCLUSION Cochlear morphology in CHARGE syndrome is variable. Whenever the cochlea was abnormal, it was almost invariably hypoplastic. This may shed light on the role of CHD7 in cochlear development. Accurate morphological description of the cochlea contributes to proper clinical diagnosis and is important for planning surgical treatment options.
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Affiliation(s)
- Martin A Lewis
- Department of Radiology, Great Ormond Street Hospital for Children NHS Foundation Trust, Great Ormond St. London, London, WC1N3JH, UK
| | - Amy Juliano
- Department of Radiology, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA
| | - Caroline Robson
- Department of Radiology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Emma Clement
- Department of Clinical Genetics, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK
| | - Robert Nash
- Department of Audiological Medicine, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK
| | - Kaukab Rajput
- Department of Audiological Medicine, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK
| | - Felice D'Arco
- Department of Radiology, Great Ormond Street Hospital for Children NHS Foundation Trust, Great Ormond St. London, London, WC1N3JH, UK. felice.d'
- Department of Radiology, Guy's and St. Thomas' NHS Foundation Trust, London, UK. felice.d'
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5
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Balendran V, Ritter KE, Martin DM. Epigenetic mechanisms of inner ear development. Hear Res 2022; 426:108440. [PMID: 35063312 PMCID: PMC9276839 DOI: 10.1016/j.heares.2022.108440] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 12/21/2021] [Accepted: 01/11/2022] [Indexed: 12/16/2022]
Abstract
Epigenetic factors are critically important for embryonic and postnatal development. Over the past decade, substantial technological advancements have occurred that now permit the study of epigenetic mechanisms that govern all aspects of inner ear development, from otocyst patterning to maturation and maintenance of hair cell stereocilia. In this review, we highlight how three major classes of epigenetic regulation (DNA methylation, histone modification, and chromatin remodeling) are essential for the development of the inner ear. We highlight open avenues for research and discuss how new tools enable the employment of epigenetic factors in regenerative and therapeutic approaches for hearing and balance disorders.
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Affiliation(s)
- Vinodh Balendran
- Neuroscience Graduate Program, University of Michigan Medical School, Ann Arbor, MI, United States
| | - K Elaine Ritter
- Department of Pediatrics, Medical Center Drive, University of Michigan Medical School, 8220C MSRB III, 1150 W, Ann Arbor, MI 48109-5652, United States
| | - Donna M Martin
- Neuroscience Graduate Program, University of Michigan Medical School, Ann Arbor, MI, United States; Department of Pediatrics, Medical Center Drive, University of Michigan Medical School, 8220C MSRB III, 1150 W, Ann Arbor, MI 48109-5652, United States; Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, United States.
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6
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Ritter KE, Lynch SM, Gorris AM, Beyer LA, Kabara L, Dolan DF, Raphael Y, Martin DM. Loss of the chromatin remodeler CHD7 impacts glial cells and myelination in the mouse cochlear spiral ganglion. Hear Res 2022; 426:108633. [PMID: 36288662 PMCID: PMC10184650 DOI: 10.1016/j.heares.2022.108633] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 09/20/2022] [Accepted: 10/11/2022] [Indexed: 11/04/2022]
Abstract
CHARGE syndrome is a multiple anomaly developmental disorder characterized by a variety of sensory deficits, including sensorineural hearing loss of unknown etiology. Most cases of CHARGE are caused by heterozygous pathogenic variants in CHD7, the gene encoding Chromodomain DNA-binding Protein 7 (CHD7), a chromatin remodeler important for the development of neurons and glial cells. Previous studies in the Chd7Gt/+ mouse model of CHARGE syndrome showed substantial neuron loss in the early stages of the developing inner ear that are compensated for by mid-gestation. In this study, we sought to determine if early developmental delays caused by Chd7 haploinsufficiency affect neurons, glial cells, and inner hair cell innervation in the mature cochlea. Analysis of auditory brainstem response recordings in Chd7Gt/+ adult animals showed elevated thresholds at 4 kHz and 16 kHz, but no differences in ABR Wave I peak latency or amplitude compared to wild type controls. Proportions of neurons in the Chd7Gt/+ adult spiral ganglion and densities of nerve projections from the spiral ganglion to the organ of Corti were not significantly different from wild type controls. Inner hair cell synapse formation also appeared unaffected in mature Chd7Gt/+ cochleae. However, histological analysis of adult Chd7Gt/+ cochleae revealed diminished satellite glial cells and hypermyelinated Type I spiral ganglion axons. We characterized the expression of CHD7 in developing inner ear glia and found CHD7 to be expressed during a tight window of inner ear development at the Schwann cell precursor stage at E9.5. While cochlear neurons appear to differentiate normally in the setting of Chd7 haploinsufficiency, our results suggest an important role for CHD7 in glial cells in the inner ear. This study highlights the dynamic nature of CHD7 activity during inner ear development in mice and contributes to understanding CHARGE syndrome pathology.
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Affiliation(s)
- K Elaine Ritter
- Department of Pediatrics, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Sloane M Lynch
- College of Literature, Science and Art, University of Michigan, Ann Arbor, MI, USA
| | - Ashley M Gorris
- College of Literature, Science and Art, University of Michigan, Ann Arbor, MI, USA
| | - Lisa A Beyer
- Department of Otolaryngology - Head and Neck Surgery, University of Medical School, Ann Arbor, MI, USA
| | - Lisa Kabara
- Department of Otolaryngology - Head and Neck Surgery, University of Medical School, Ann Arbor, MI, USA
| | - David F Dolan
- Department of Otolaryngology - Head and Neck Surgery, University of Medical School, Ann Arbor, MI, USA
| | - Yehoash Raphael
- Department of Otolaryngology - Head and Neck Surgery, University of Medical School, Ann Arbor, MI, USA
| | - Donna M Martin
- Department of Pediatrics, University of Michigan Medical School, Ann Arbor, MI, USA; Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, USA.
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7
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Guo J, Ma X, Skidmore JM, Cimerman J, Prieskorn DM, Beyer LA, Swiderski DL, Dolan DF, Martin DM, Raphael Y. GJB2 gene therapy and conditional deletion reveal developmental stage-dependent effects on inner ear structure and function. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2021; 23:319-333. [PMID: 34729379 PMCID: PMC8531464 DOI: 10.1016/j.omtm.2021.09.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 09/24/2021] [Indexed: 11/15/2022]
Abstract
Pathogenic variants in GJB2, the gene encoding connexin 26, are the most common cause of autosomal-recessive hereditary deafness. Despite this high prevalence, pathogenic mechanisms leading to GJB2-related deafness are not well understood, and cures are absent. Humans with GJB2-related deafness retain at least some auditory hair cells and neurons, and their deafness is usually stable. In contrast, mice with conditional loss of Gjb2 in supporting cells exhibit extensive loss of hair cells and neurons and rapidly progress to profound deafness, precluding the application of therapies that require intact cochlear cells. In an attempt to design a less severe Gjb2 animal model, we generated mice with inducible Sox10iCre ERT2 -mediated loss of Gjb2. Tamoxifen injection led to reduced connexin 26 expression and impaired function, but cochlear hair cells and neurons survived for 2 months, allowing phenotypic rescue attempts within this time. AAV-mediated gene transfer of GJB2 in mature mutant ears did not demonstrate threshold improvement and in some animals exacerbated hearing loss and resulted in hair cell loss. We conclude that Sox10iCre ERT2 ;Gjb2 flox/flox mice are valuable for studying the biology of connexin 26 in the cochlea. In particular, these mice may be useful for evaluating gene therapy vectors and development of therapies for GJB2-related deafness.
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Affiliation(s)
- Jingying Guo
- Kresge Hearing Research Institute, Otolaryngology, Head and Neck Surgery, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA.,Department of Otolaryngology Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Xiaobo Ma
- Department of Otolaryngology Head and Neck Surgery, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Jennifer M Skidmore
- Department of Pediatrics, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Jelka Cimerman
- Department of Pediatrics, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Diane M Prieskorn
- Kresge Hearing Research Institute, Otolaryngology, Head and Neck Surgery, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Lisa A Beyer
- Kresge Hearing Research Institute, Otolaryngology, Head and Neck Surgery, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Donald L Swiderski
- Kresge Hearing Research Institute, Otolaryngology, Head and Neck Surgery, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
| | - David F Dolan
- Kresge Hearing Research Institute, Otolaryngology, Head and Neck Surgery, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Donna M Martin
- Department of Pediatrics, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA.,Department of Human Genetics, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Yehoash Raphael
- Kresge Hearing Research Institute, Otolaryngology, Head and Neck Surgery, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
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8
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Ahmed M, Moon R, Prajapati RS, James E, Basson MA, Streit A. The chromatin remodelling factor Chd7 protects auditory neurons and sensory hair cells from stress-induced degeneration. Commun Biol 2021; 4:1260. [PMID: 34732824 PMCID: PMC8566505 DOI: 10.1038/s42003-021-02788-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 10/08/2021] [Indexed: 11/08/2022] Open
Abstract
Neurons and sensory cells are particularly vulnerable to oxidative stress due to their high oxygen demand during stimulus perception and transmission. The mechanisms that protect them from stress-induced death and degeneration remain elusive. Here we show that embryonic deletion of the chromodomain helicase DNA-binding protein 7 (CHD7) in auditory neurons or hair cells leads to sensorineural hearing loss due to postnatal degeneration of both cell types. Mechanistically, we demonstrate that CHD7 controls the expression of major stress pathway components. In its absence, hair cells are hypersensitive, dying rapidly after brief exposure to stress inducers, suggesting that sound at the onset of hearing triggers their degeneration. In humans, CHD7 haploinsufficiency causes CHARGE syndrome, a disorder affecting multiple organs including the ear. Our findings suggest that CHD7 mutations cause developmentally silent phenotypes that predispose cells to postnatal degeneration due to a failure of protective mechanisms.
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Affiliation(s)
- Mohi Ahmed
- Centre for Craniofacial and Regenerative Biology, Floor 27 Tower Wing, Guy's Hospital, King's College London, London, SE1 9RT, UK.
| | - Ruth Moon
- Centre for Craniofacial and Regenerative Biology, Floor 27 Tower Wing, Guy's Hospital, King's College London, London, SE1 9RT, UK
| | - Ravindra Singh Prajapati
- Centre for Craniofacial and Regenerative Biology, Floor 27 Tower Wing, Guy's Hospital, King's College London, London, SE1 9RT, UK
- Leukaemia and Stem Cell Biology Group, School of Cancer and Pharmaceutical Sciences, King's College London, London, SE5 9NU, UK
| | - Elysia James
- Wolfson Centre for Age-Related Diseases, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, SE1 1UL, UK
| | - M Albert Basson
- Centre for Craniofacial and Regenerative Biology, Floor 27 Tower Wing, Guy's Hospital, King's College London, London, SE1 9RT, UK
- MRC Centre for Neurodevelopmental Disorders, King's College London, London, SE1 1UL, UK
| | - Andrea Streit
- Centre for Craniofacial and Regenerative Biology, Floor 27 Tower Wing, Guy's Hospital, King's College London, London, SE1 9RT, UK.
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9
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Balendran V, Skidmore JM, Ritter KE, Gao J, Cimerman J, Beyer LA, Hurd EA, Raphael Y, Martin DM. Chromatin remodeler CHD7 is critical for cochlear morphogenesis and neurosensory patterning. Dev Biol 2021; 477:11-21. [PMID: 34004180 DOI: 10.1016/j.ydbio.2021.05.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 04/12/2021] [Accepted: 05/10/2021] [Indexed: 11/18/2022]
Abstract
Epigenetic regulation of gene transcription by chromatin remodeling proteins has recently emerged as an important contributing factor in inner ear development. Pathogenic variants in CHD7, the gene encoding Chromodomain Helicase DNA binding protein 7, cause CHARGE syndrome, which presents with malformations in the developing ear. Chd7 is broadly expressed in the developing mouse otocyst and mature auditory epithelium, yet the pathogenic effects of Chd7 loss in the cochlea are not well understood. Here we characterized cochlear epithelial phenotypes in mice with deletion of Chd7 throughout the otocyst (using Foxg1Cre/+ and Pax2Cre), in the otic mesenchyme (using TCre), in hair cells (using Atoh1Cre), in developing neuroblasts (using NgnCre), or in spiral ganglion neurons (using ShhCre/+). Pan-otic deletion of Chd7 resulted in shortened cochleae with aberrant projections and axonal looping, disorganized, supernumerary hair cells at the apical turn and a narrowed epithelium with missing hair cells in the middle region. Deletion of Chd7 in the otic mesenchyme had no effect on overall cochlear morphology. Loss of Chd7 in hair cells did not disrupt their formation or organization of the auditory epithelium. Similarly, absence of Chd7 in spiral ganglion neurons had no effect on axonal projections. In contrast, deletion of Chd7 in developing neuroblasts led to smaller spiral ganglia and disorganized cochlear neurites. Together, these observations reveal dosage-, tissue-, and time-sensitive cell autonomous roles for Chd7 in cochlear elongation and cochlear neuron organization, with minimal functions for Chd7 in hair cells. These studies provide novel information about roles for Chd7 in development of auditory neurons.
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Affiliation(s)
- Vinodh Balendran
- Departments of Pediatrics, The University of Michigan, Ann Arbor, MI, USA
| | | | - K Elaine Ritter
- Departments of Pediatrics, The University of Michigan, Ann Arbor, MI, USA
| | - Jingxia Gao
- Departments of Pediatrics, The University of Michigan, Ann Arbor, MI, USA
| | - Jelka Cimerman
- Departments of Pediatrics, The University of Michigan, Ann Arbor, MI, USA
| | - Lisa A Beyer
- Otolaryngology - Head and Neck Surgery, The University of Michigan, Ann Arbor, MI, USA
| | | | - Yehoash Raphael
- Otolaryngology - Head and Neck Surgery, The University of Michigan, Ann Arbor, MI, USA
| | - Donna M Martin
- Departments of Pediatrics, The University of Michigan, Ann Arbor, MI, USA; Otolaryngology - Head and Neck Surgery, The University of Michigan, Ann Arbor, MI, USA; Human Genetics, The University of Michigan, Ann Arbor, MI, USA.
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10
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Evsen L, Li X, Zhang S, Razin S, Doetzlhofer A. let-7 miRNAs inhibit CHD7 expression and control auditory-sensory progenitor cell behavior in the developing inner ear. Development 2020; 147:147/15/dev183384. [PMID: 32816902 DOI: 10.1242/dev.183384] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 07/07/2020] [Indexed: 11/20/2022]
Abstract
The evolutionarily conserved lethal-7 (let-7) microRNAs (miRNAs) are well-known activators of proliferative quiescence and terminal differentiation. However, in the murine auditory organ, let-7g overexpression delays the differentiation of mechano-sensory hair cells (HCs). To address whether the role of let-7 in auditory-sensory differentiation is conserved among vertebrates, we manipulated let-7 levels within the chicken auditory organ: the basilar papilla. Using a let-7 sponge construct to sequester let-7 miRNAs, we found that endogenous let-7 miRNAs are essential for limiting the self-renewal of HC progenitor cells. Furthermore, let-7b overexpression experiments revealed that, similar to mice, higher than normal let-7 levels slow/delay HC differentiation. Finally, we identify CHD7, a chromatin remodeler, as a candidate for mediating the repressive function of let-7 in HC differentiation and inner ear morphogenesis. Our analysis uncovered an evolutionarily conserved let-7-5p-binding site within the chicken Chd7 gene and its human and murine homologs, and we show that let-7g overexpression in mice limits CHD7 expression in the developing inner ear, retina and brain. Haploinsufficiency of CHD7 in humans causes CHARGE syndrome and attenuation of let-7 function may be an effective method for treating CHD7 deficiency.
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Affiliation(s)
- Lale Evsen
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Xiaojun Li
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Shuran Zhang
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Sharjil Razin
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Angelika Doetzlhofer
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA .,Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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11
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Ritter KE, Martin DM. Neural crest contributions to the ear: Implications for congenital hearing disorders. Hear Res 2018; 376:22-32. [PMID: 30455064 DOI: 10.1016/j.heares.2018.11.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 10/30/2018] [Accepted: 11/12/2018] [Indexed: 12/16/2022]
Abstract
Congenital hearing disorders affect millions of children worldwide and can significantly impact acquisition of speech and language. Efforts to identify the developmental genetic etiologies of conductive and sensorineural hearing losses have revealed critical roles for cranial neural crest cells (NCCs) in ear development. Cranial NCCs contribute to all portions of the ear, and defects in neural crest development can lead to neurocristopathies associated with profound hearing loss. The molecular mechanisms governing the development of neural crest derivatives within the ear are partially understood, but many questions remain. In this review, we describe recent advancements in determining neural crest contributions to the ear, how they inform our understanding of neurocristopathies, and highlight new avenues for further research using bioinformatic approaches.
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Affiliation(s)
- K Elaine Ritter
- Department of Pediatrics, The University of Michigan Medical School, Ann Arbor, MI, USA
| | - Donna M Martin
- Department of Pediatrics, The University of Michigan Medical School, Ann Arbor, MI, USA; Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, USA.
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12
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Durruthy-Durruthy R, Sperry ED, Bowen ME, Attardi LD, Heller S, Martin DM. Single Cell Transcriptomics Reveal Abnormalities in Neurosensory Patterning of the Chd7 Mutant Mouse Ear. Front Genet 2018; 9:473. [PMID: 30459807 PMCID: PMC6232929 DOI: 10.3389/fgene.2018.00473] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Accepted: 09/25/2018] [Indexed: 12/11/2022] Open
Abstract
The chromatin remodeling protein CHD7 is critical for proper formation of the mammalian inner ear. Humans with heterozygous pathogenic variants in CHD7 exhibit CHARGE syndrome, characterized by hearing loss and inner ear dysplasia, including abnormalities of the semicircular canals and Mondini malformations. Chd7Gt/+ heterozygous null mutant mice also exhibit dysplastic semicircular canals and hearing loss. Prior studies have demonstrated that reduced Chd7 dosage in the ear disrupts expression of genes involved in morphogenesis and neurogenesis, yet the relationships between these changes in gene expression and otic patterning are not well understood. Here, we sought to define roles for CHD7 in global regulation of gene expression and patterning in the developing mouse ear. Using single-cell multiplex qRT-PCR, we analyzed expression of 192 genes in FAC sorted cells from Pax2Cre;mT/mGFP wild type and Chd7Gt/+ mutant microdissected mouse otocysts. We found that Chd7 haploinsufficient otocysts exhibit a relative enrichment of cells adopting a neuroblast (vs. otic) transcriptional identity compared with wild type. Additionally, we uncovered disruptions in pro-sensory and pro-neurogenic gene expression with Chd7 loss, including genes encoding proteins that function in Notch signaling. Our results suggest that Chd7 is required for early cell fate decisions in the developing ear that involve highly specific aspects of otic patterning and differentiation.
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Affiliation(s)
- Robert Durruthy-Durruthy
- Departments of Otolaryngology - Head and Neck Surgery, Stanford University, Stanford, CA, United States
| | - Ethan D Sperry
- Medical Scientist Training Program, University of Michigan, Ann Arbor, MI, United States.,Department of Human Genetics, University of Michigan, Ann Arbor, MI, United States
| | - Margot E Bowen
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University, Stanford, CA, United States
| | - Laura D Attardi
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, Stanford University, Stanford, CA, United States
| | - Stefan Heller
- Departments of Otolaryngology - Head and Neck Surgery, Stanford University, Stanford, CA, United States
| | - Donna M Martin
- Medical Scientist Training Program, University of Michigan, Ann Arbor, MI, United States.,Department of Human Genetics, University of Michigan, Ann Arbor, MI, United States.,Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, MI, United States
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13
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Carlson K, Schacht J, Neitzel RL. Assessing ototoxicity due to chronic lead and cadmium intake with and without noise exposure in the mature mouse. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2018; 81:1041-1057. [PMID: 30239325 PMCID: PMC6349363 DOI: 10.1080/15287394.2018.1521320] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 09/04/2018] [Accepted: 09/05/2018] [Indexed: 05/27/2023]
Abstract
Exposure to heavy metals may lead to hearing impairment. However, experimental studies have not explored this issue with and without noise exposure in mature animals with environmentally relevant doses. The aim of this study was to investigate ototoxicity produced by lead (Pb) and cadmium (Cd) and noise, singly and in combination, in the adult CBA/CaJ mouse. Metals were delivered via drinking water (0.03 mM, 1 mM, and 3 mM Pb; or 30, 100, and 300 μM Cd) for 12 weeks, resulting in environmentally- and occupationally relevant mean (± standard deviations) blood levels of Pb (2.89 ± 0.44, 38.5 ± 4.9, and 60.1 ± 6.6 μg/dl, respectively) and Cd (1.3 ± 0.23, 6.37 ± 0.87, 27.2 ± 4.1 μg/L, respectively). Metal treatment was also combined with a noise exposure consisting of a 105 dB broadband (2-20 kHz) stimulus for 2 hr or a sham exposure. Auditory performance was determined by comparing auditory brainstem responses (ABR) and distortion product otoacoustic emissions (DPOAE) at baseline and after 11 weeks of metal treatment. Metal-exposed animals did not develop significant auditory deficits and did not exhibit morphological damage to cochlear hair cells. In contrast, noise-exposed animals, including those exposed to combinations of metals and noise, demonstrated significant hair cell loss, reduced DPOAE amplitudes, and ABR threshold shifts of 42.2 ± 13 dB at 32 kHz (105 dB noise alone). No significant potentiation or synergistic effects were found in groups exposed to multiple agents. This study establishes a highly reproducible adult mouse model that may be used to evaluate a variety of environmental exposure mixtures.
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Affiliation(s)
- Krystin Carlson
- Department of Environmental Health Sciences Department, University of Michigan, Ann Arbor, USA
| | - Jochen Schacht
- Kresge Hearing Research Institute, University of Michigan, Ann Arbor, USA
| | - Richard L Neitzel
- Department of Environmental Health Sciences Department, University of Michigan, Ann Arbor, USA
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14
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Yao H, Hill SF, Skidmore JM, Sperry ED, Swiderski DL, Sanchez GJ, Bartels CF, Raphael Y, Scacheri PC, Iwase S, Martin DM. CHD7 represses the retinoic acid synthesis enzyme ALDH1A3 during inner ear development. JCI Insight 2018; 3:97440. [PMID: 29467333 DOI: 10.1172/jci.insight.97440] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 01/23/2018] [Indexed: 12/13/2022] Open
Abstract
CHD7, an ATP-dependent chromatin remodeler, is disrupted in CHARGE syndrome, an autosomal dominant disorder characterized by variably penetrant abnormalities in craniofacial, cardiac, and nervous system tissues. The inner ear is uniquely sensitive to CHD7 levels and is the most commonly affected organ in individuals with CHARGE. Interestingly, upregulation or downregulation of retinoic acid (RA) signaling during embryogenesis also leads to developmental defects similar to those in CHARGE syndrome, suggesting that CHD7 and RA may have common target genes or signaling pathways. Here, we tested three separate potential mechanisms for CHD7 and RA interaction: (a) direct binding of CHD7 with RA receptors, (b) regulation of CHD7 levels by RA, and (c) CHD7 binding and regulation of RA-related genes. We show that CHD7 directly regulates expression of Aldh1a3, the gene encoding the RA synthetic enzyme ALDH1A3 and that loss of Aldh1a3 partially rescues Chd7 mutant mouse inner ear defects. Together, these studies indicate that ALDH1A3 acts with CHD7 in a common genetic pathway to regulate inner ear development, providing insights into how CHD7 and RA regulate gene expression and morphogenesis in the developing embryo.
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Affiliation(s)
- Hui Yao
- Department of Pediatrics and Communicable Diseases
| | | | | | - Ethan D Sperry
- Department of Human Genetics.,Medical Scientist Training Program, and
| | - Donald L Swiderski
- Department of Otolaryngology, University of Michigan, Ann Arbor, Michigan, USA
| | | | - Cynthia F Bartels
- Department of Genetics, Case Western Reserve University, Cleveland, Ohio, USA
| | - Yehoash Raphael
- Department of Otolaryngology, University of Michigan, Ann Arbor, Michigan, USA
| | - Peter C Scacheri
- Department of Genetics, Case Western Reserve University, Cleveland, Ohio, USA
| | | | - Donna M Martin
- Department of Pediatrics and Communicable Diseases.,Department of Human Genetics.,Medical Scientist Training Program, and
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15
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van Ravenswaaij-Arts C, Martin DM. New insights and advances in CHARGE syndrome: Diagnosis, etiologies, treatments, and research discoveries. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2017; 175:397-406. [PMID: 29171162 DOI: 10.1002/ajmg.c.31592] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 10/02/2017] [Accepted: 10/04/2017] [Indexed: 01/17/2023]
Abstract
CHARGE syndrome is a multiple congenital anomaly condition caused, in a majority of individuals, by loss of function pathogenic variants in the gene CHD7. In this special issue of the American Journal of Medical Genetics part C, authors of eleven manuscripts describe specific organ system features of CHARGE syndrome, with a focus on recent developments in diagnosis, etiologies, and treatments. Since 2004, when CHD7 was identified as the major causative gene in CHARGE, several animal models (mice, zebrafish, flies, and frog) and cell-based systems have been developed to explore the underlying pathophysiology of this condition. In this article, we summarize those advances, highlight opportunities for new discoveries, and encourage readers to explore specific organ systems in more detail in each individual article. We hope the excitement around innovative research and development in CHARGE syndrome will encourage others to join this effort, and will stimulate other investigators and professionals to engage with individuals diagnosed as having CHARGE syndrome, their families, and their care providers.
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Affiliation(s)
- Conny van Ravenswaaij-Arts
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
| | - Donna M Martin
- Departments of Human Genetics, The University of Michigan Medical School, Ann Arbor, Michigan.,Departments of Pediatrics, The University of Michigan Medical School, Ann Arbor, Michigan
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16
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Choo DI, Tawfik KO, Martin DM, Raphael Y. Inner ear manifestations in CHARGE: Abnormalities, treatments, animal models, and progress toward treatments in auditory and vestibular structures. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2017; 175:439-449. [PMID: 29082607 DOI: 10.1002/ajmg.c.31587] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 09/18/2017] [Accepted: 09/22/2017] [Indexed: 12/25/2022]
Abstract
The inner ear contains the sensory organs for hearing and balance. Both hearing and balance are commonly affected in individuals with CHARGE syndrome (CS), an autosomal dominant condition caused by heterozygous pathogenic variants in the CHD7 gene. Semicircular canal dysplasia or aplasia is the single most prevalent feature in individuals with CHARGE leading to deficient gross motor skills and ambulation. Identification of CHD7 as the major gene affected in CHARGE has enabled acceleration of research in this field. Great progress has been made in understanding the role of CHD7 in the development and function of the inner ear, as well as in related organs such as the middle ear and auditory and vestibular neural pathways. The goals of current research on CHD7 and CS are to (a) improve our understanding of the pathology caused by CHD7 pathogenic variants and (b) to provide better tools for prognosis and treatment. Current studies utilize cells and whole animals, from flies to mammals. The mouse is an excellent model for exploring mechanisms of Chd7 function in the ear, given the evolutionary conservation of ear structure, function, Chd7 expression, and similarity of mutant phenotypes between mice and humans. Newly recognized developmental functions for mouse Chd7 are shedding light on how abnormalities in CHD7 might lead to CS symptoms in humans. Here we review known human inner ear phenotypes associated with CHD7 pathogenic variants and CS, summarize progress toward diagnosis and treatment of inner ear-related pathologies, and explore new avenues for treatment based on basic science discoveries.
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Affiliation(s)
- Daniel I Choo
- Department of Otolaryngology-Head and Neck Surgery, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Kareem O Tawfik
- Department of Otolaryngology-Head and Neck Surgery, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Donna M Martin
- Departments of Pediatrics, The University of Michigan Medical School, Ann Arbor, Michigan.,Department of Human Genetics, The University of Michigan Medical School, Ann Arbor, Michigan
| | - Yehoash Raphael
- Department of Otolaryngology-Head and Neck Surgery, The University of Michigan Medical School, Ann Arbor, Michigan
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17
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Doetzlhofer A, Avraham KB. Insights into inner ear-specific gene regulation: Epigenetics and non-coding RNAs in inner ear development and regeneration. Semin Cell Dev Biol 2017; 65:69-79. [PMID: 27836639 PMCID: PMC5512292 DOI: 10.1016/j.semcdb.2016.11.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Revised: 10/14/2016] [Accepted: 11/03/2016] [Indexed: 12/12/2022]
Abstract
The vertebrate inner ear houses highly specialized sensory organs, tuned to detect and encode sound, head motion and gravity. Gene expression programs under the control of transcription factors orchestrate the formation and specialization of the non-sensory inner ear labyrinth and its sensory constituents. More recently, epigenetic factors and non-coding RNAs emerged as an additional layer of gene regulation, both in inner ear development and disease. In this review, we provide an overview on how epigenetic modifications and non-coding RNAs, in particular microRNAs (miRNAs), influence gene expression and summarize recent discoveries that highlight their critical role in the proper formation of the inner ear labyrinth and its sensory organs. Finally, we discuss recent insights into how epigenetic factors and miRNAs may facilitate, or in the case of mammals, restrict inner ear sensory hair cell regeneration.
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Affiliation(s)
- Angelika Doetzlhofer
- The Solomon H. Snyder Department of Neuroscience, the Center for Sensory Biology, the Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA.
| | - Karen B Avraham
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel.
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18
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Mills AA. The Chromodomain Helicase DNA-Binding Chromatin Remodelers: Family Traits that Protect from and Promote Cancer. Cold Spring Harb Perspect Med 2017; 7:cshperspect.a026450. [PMID: 28096241 DOI: 10.1101/cshperspect.a026450] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
A plethora of mutations in chromatin regulators in diverse human cancers is emerging, attesting to the pivotal role of chromatin dynamics in tumorigenesis. A recurrent theme is inactivation of the chromodomain helicase DNA-binding (CHD) family of proteins-ATP-dependent chromatin remodelers that govern the cellular machinery's access to DNA, thereby controlling fundamental processes, including transcription, proliferation, and DNA damage repair. This review highlights what is currently known about how genetic and epigenetic perturbation of CHD proteins and the pathways that they regulate set the stage for cancer, providing new insight for designing more effective anti-cancer therapies.
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Affiliation(s)
- Alea A Mills
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, 11724
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19
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Chhan D, McKinnon ML, Rosowski JJ. Identification of induced and naturally occurring conductive hearing loss in mice using bone conduction. Hear Res 2017; 346:45-54. [PMID: 28167132 DOI: 10.1016/j.heares.2017.02.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 01/04/2017] [Accepted: 02/01/2017] [Indexed: 01/05/2023]
Abstract
While many mouse models of hearing loss have been described, a significant fraction of the genetic defects in these models affect both the inner ear and middle ears. A common method used to separate inner-ear (sensory-neural) from middle-ear (conductive) pathologies in the hearing clinic is the combination of air-conduction and bone-conduction audiometry. In this report, we investigate the use of air- and bone-conducted evoked auditory brainstem responses to perform a similar separation in mice. We describe a technique by which we stimulate the mouse ear both acoustically and via whole-head vibration. We investigate the sensitivity of this technique to conductive hearing loss by introducing middle-ear lesions in normal hearing mice. We also use the technique to investigate the presence of an age-related conductive hearing loss in a common mouse model of presbycusis, the BALB/c mouse.
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Affiliation(s)
- David Chhan
- Army Research Lab, Aberdeen Proving Ground, MD, USA.
| | - Melissa L McKinnon
- Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, MA, USA.
| | - John J Rosowski
- Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, MA, USA; Department of Otolaryngology, Harvard Medical School, Boston, MA, USA.
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20
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Abstract
Unrestrained p53 activity during development, as occurs upon loss of the p53 negative regulators Mdm2 or Mdmx, causes early embryonic lethality. Surprisingly, co-expression of wild-type p53 and a transcriptionally-dead variant of p53, with mutations in both transactivation domains (p53(L25Q,W26S,F53Q,F54S)), also causes lethality, but later in gestation and in association with a host of very specific phenotypes reminiscent of a syndrome known as CHARGE. Molecular analyses revealed that wild-type p53 is inappropriately activated in p53(5,26,53,54/)(+) embryos, triggering cell-cycle arrest or apoptosis during development to cause CHARGE phenotypes. In addition, CHARGE syndrome is typically caused by mutations in the CHD7 chromatin remodeler, and we have shown that activated p53 contributes to phenotypes caused by CHD7-deficiency. Together, these studies provide new insight into CHARGE syndrome and expand our understanding of the role of p53 in diseases other than cancer.
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Affiliation(s)
- Jeanine L Van Nostrand
- a Division of Radiation and Cancer Biology; Department of Radiation Oncology ; Stanford School of Medicine ; Stanford , CA USA
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21
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Nishio SY, Hattori M, Moteki H, Tsukada K, Miyagawa M, Naito T, Yoshimura H, Iwasa YI, Mori K, Shima Y, Sakuma N, Usami SI. Gene expression profiles of the cochlea and vestibular endorgans: localization and function of genes causing deafness. Ann Otol Rhinol Laryngol 2015; 124 Suppl 1:6S-48S. [PMID: 25814645 DOI: 10.1177/0003489415575549] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
OBJECTIVES We sought to elucidate the gene expression profiles of the causative genes as well as the localization of the encoded proteins involved in hereditary hearing loss. METHODS Relevant articles (as of September 2014) were searched in PubMed databases, and the gene symbols of the genes reported to be associated with deafness were located on the Hereditary Hearing Loss Homepage using localization, expression, and distribution as keywords. RESULTS Our review of the literature allowed us to systematize the gene expression profiles for genetic deafness in the inner ear, clarifying the unique functions and specific expression patterns of these genes in the cochlea and vestibular endorgans. CONCLUSIONS The coordinated actions of various encoded molecules are essential for the normal development and maintenance of auditory and vestibular function.
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Affiliation(s)
- Shin-Ya Nishio
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan Department of Hearing Implant Sciences, Shinshu University School of Medicine, Matsumoto, Japan
| | - Mitsuru Hattori
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Hideaki Moteki
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Keita Tsukada
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Maiko Miyagawa
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan Department of Hearing Implant Sciences, Shinshu University School of Medicine, Matsumoto, Japan
| | - Takehiko Naito
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Hidekane Yoshimura
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Yoh-Ichiro Iwasa
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Kentaro Mori
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Yutaka Shima
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan
| | - Naoko Sakuma
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan Department of Otorhinolaryngology and Head and Neck Surgery, Yokohama City University School of Medicine, Yokohama, Japan
| | - Shin-Ichi Usami
- Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan Department of Hearing Implant Sciences, Shinshu University School of Medicine, Matsumoto, Japan
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22
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Ghosh R, Vegesna S, Safi R, Bao H, Zhang B, Marenda DR, Liebl FLW. Kismet positively regulates glutamate receptor localization and synaptic transmission at the Drosophila neuromuscular junction. PLoS One 2014; 9:e113494. [PMID: 25412171 PMCID: PMC4239079 DOI: 10.1371/journal.pone.0113494] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Accepted: 10/24/2014] [Indexed: 12/20/2022] Open
Abstract
The Drosophila neuromuscular junction (NMJ) is a glutamatergic synapse that is structurally and functionally similar to mammalian glutamatergic synapses. These synapses can, as a result of changes in activity, alter the strength of their connections via processes that require chromatin remodeling and changes in gene expression. The chromodomain helicase DNA binding (CHD) protein, Kismet (Kis), is expressed in both motor neuron nuclei and postsynaptic muscle nuclei of the Drosophila larvae. Here, we show that Kis is important for motor neuron synaptic morphology, the localization and clustering of postsynaptic glutamate receptors, larval motor behavior, and synaptic transmission. Our data suggest that Kis is part of the machinery that modulates the development and function of the NMJ. Kis is the homolog to human CHD7, which is mutated in CHARGE syndrome. Thus, our data suggest novel avenues of investigation for synaptic defects associated with CHARGE syndrome.
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Affiliation(s)
- Rupa Ghosh
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, United States of America
| | - Srikar Vegesna
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, United States of America
| | - Ramia Safi
- Department of Biological Sciences, Southern Illinois University Edwardsville, Edwardsville, Illinois, United States of America
| | - Hong Bao
- Division of Biological Sciences, University of Missouri, Columbia, Missouri, United States of America
| | - Bing Zhang
- Division of Biological Sciences, University of Missouri, Columbia, Missouri, United States of America
| | - Daniel R. Marenda
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, United States of America
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania, United States of America
- * E-mail: (FLWL); (DRM)
| | - Faith L. W. Liebl
- Department of Biological Sciences, Southern Illinois University Edwardsville, Edwardsville, Illinois, United States of America
- * E-mail: (FLWL); (DRM)
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23
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Sperry ED, Hurd EA, Durham MA, Reamer EN, Stein AB, Martin DM. The chromatin remodeling protein CHD7, mutated in CHARGE syndrome, is necessary for proper craniofacial and tracheal development. Dev Dyn 2014; 243:1055-66. [PMID: 24975120 DOI: 10.1002/dvdy.24156] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Revised: 06/06/2014] [Accepted: 06/20/2014] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Heterozygous mutations in the chromatin remodeling gene CHD7 cause CHARGE syndrome, a developmental disorder with variable craniofacial dysmorphisms and respiratory difficulties. The molecular etiologies of these malformations are not well understood. Homozygous Chd7 null mice die by E11, whereas Chd7(Gt/+) heterozygous null mice are a viable and excellent model of CHARGE. We explored skeletal phenotypes in Chd7(Gt/+) and Chd7 conditional knockout mice, using Foxg1-Cre to delete Chd7 (Foxg1-CKO) in the developing eye, ear, nose, pharyngeal pouch, forebrain, and gut and Wnt1-Cre (Wnt1-CKO) to delete Chd7 in migrating neural crest cells. RESULTS Foxg1-CKO mice exhibited postnatal respiratory distress and death, dysplasia of the eye, concha, and frontal bone, hypoplastic maxillary shelves and nasal epithelia, and reduced tracheal rings. Wnt1-CKO mice exhibited frontal and occipital bone dysplasia, hypoplasia of the maxillary shelves and mandible, and cleft palate. In contrast, heterozygous Chd7(Gt/+) mice had apparently normal skeletal development. CONCLUSIONS Conditional deletion of Chd7 in ectodermal and endodermal derivatives (Foxg1-Cre) or migrating neural crest cells (Wnt1-Cre) results in varied and more severe craniofacial defects than in Chd7(Gt/+) mice. These studies indicate that CHD7 has an important, dosage-dependent role in development of several different craniofacial tissues.
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Affiliation(s)
- Ethan D Sperry
- Department of Human Genetics, The University of Michigan, Ann Arbor, Michigan; The Medical School, The University of Michigan, Ann Arbor, Michigan; Medical Scientist Training Program, The University of Michigan, Ann Arbor, Michigan
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24
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Ogier JM, Carpinelli MR, Arhatari BD, Symons RCA, Kile BT, Burt RA. CHD7 deficiency in "Looper", a new mouse model of CHARGE syndrome, results in ossicle malformation, otosclerosis and hearing impairment. PLoS One 2014; 9:e97559. [PMID: 24840056 PMCID: PMC4026240 DOI: 10.1371/journal.pone.0097559] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 04/21/2014] [Indexed: 12/13/2022] Open
Abstract
CHARGE syndrome is a rare human disorder caused by mutations in the gene encoding chromodomain helicase DNA binding protein 7 (CHD7). Characteristics of CHARGE are varied and include developmental ear and hearing anomalies. Here we report a novel mouse model of CHD7 dysfunction, termed Looper. The Looper strain harbours a nonsense mutation (c.5690C>A, p.S1897X) within the Chd7 gene. Looper mice exhibit many of the clinical features of the human syndrome, consistent with previously reported CHARGE models, including growth retardation, facial asymmetry, vestibular defects, eye anomalies, hyperactivity, ossicle malformation, hearing loss and vestibular dysfunction. Looper mice display an otosclerosis-like fusion of the stapes footplate to the cochlear oval window and blepharoconjunctivitis but not coloboma. Looper mice are hyperactive and have vestibular dysfunction but do not display motor impairment.
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Affiliation(s)
| | - Marina R. Carpinelli
- Murdoch Childrens Research Institute, Parkville, Victoria, Australia
- The HEARing Cooperative Research Centre, Parkville, Victoria, Australia
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia
| | - Benedicta D. Arhatari
- ARC Centre of Excellence for Coherent X-ray Science, Department of Physics, La Trobe University, Bundoora, Victoria, Australia
| | - R. C. Andrew Symons
- Department of Ophthalmology, Royal Melbourne Hospital, Parkville, Victoria, Australia
| | - Benjamin T. Kile
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia
- Department of Genetics, University of Melbourne, Parkville, Victoria, Australia
| | - Rachel A. Burt
- Murdoch Childrens Research Institute, Parkville, Victoria, Australia
- The HEARing Cooperative Research Centre, Parkville, Victoria, Australia
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
- Department of Genetics, University of Melbourne, Parkville, Victoria, Australia
- Department of Paediatrics, University of Melbourne, Parkville, Victoria, Australia
- * E-mail:
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25
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Liu Y, Harmelink C, Peng Y, Chen Y, Wang Q, Jiao K. CHD7 interacts with BMP R-SMADs to epigenetically regulate cardiogenesis in mice. Hum Mol Genet 2013; 23:2145-56. [PMID: 24293546 DOI: 10.1093/hmg/ddt610] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Haploinsufficiency for CHD7, an ATP-dependent nucleosome remodeling factor, is the leading cause of CHARGE syndrome. While congenital heart defects (CHDs) are major clinical features of CHARGE syndrome, affecting >75% of patients, it remains unclear whether CHD7 can directly regulate cardiogenic genes in embryos. Our complementary yeast two-hybrid and biochemical assays reveal that CHD7 is a novel interaction partner of canonical BMP signaling pathway nuclear mediators, SMAD1/5/8, in the embryonic heart. Moreover, CHD7 associates in a BMP-dependent manner with the enhancers of a critical cardiac transcription factor, Nkx2.5, that contain functional SMAD1-binding elements. Both the active epigenetic signature of Nkx2.5 regulatory elements and its proper expression in cardiomyocytes require CHD7. Finally, inactivation of Chd7 in mice impairs multiple BMP signaling-regulated cardiogenic processes. Our results thus support the model that CHD7 is recruited by SMAD1/5/8 to the enhancers of BMP-targeted cardiogenic genes to epigenetically regulate their expression. Impaired BMP activities in embryonic hearts may thus have a major contribution to CHDs in CHARGE syndrome.
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Affiliation(s)
- Yuelong Liu
- Department of Genetics and Department of Cell, Developmental and Integrative Biology, The University of Alabama at Birmingham, Birmingham, AL 35294, USA
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26
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Micucci JA, Layman WS, Hurd EA, Sperry ED, Frank SF, Durham MA, Swiderski DL, Skidmore JM, Scacheri PC, Raphael Y, Martin DM. CHD7 and retinoic acid signaling cooperate to regulate neural stem cell and inner ear development in mouse models of CHARGE syndrome. Hum Mol Genet 2013; 23:434-48. [PMID: 24026680 DOI: 10.1093/hmg/ddt435] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
CHARGE syndrome is a multiple congenital anomaly disorder that leads to life-threatening birth defects, such as choanal atresia and cardiac malformations as well as multiple sensory impairments, that affect hearing, vision, olfaction and balance. CHARGE is caused by heterozygous mutations in CHD7, which encodes an ATP-dependent chromatin remodeling enzyme. Identification of the mechanisms underlying neurological and sensory defects in CHARGE is a first step toward developing treatments for CHARGE individuals. Here, we used mouse models of Chd7 deficiency to explore the function of CHD7 in the development of the subventricular zone (SVZ) neural stem cell niche and inner ear, structures that are important for olfactory bulb neurogenesis and hearing and balance, respectively. We found that loss of Chd7 results in cell-autonomous proliferative, neurogenic and self-renewal defects in the perinatal and mature mouse SVZ stem cell niche. Modulation of retinoic acid (RA) signaling prevented in vivo inner ear and in vitro neural stem cell defects caused by Chd7 deficiency. Our findings demonstrate critical, cooperative roles for RA and CHD7 in SVZ neural stem cell function and inner ear development, suggesting that altered RA signaling may be an effective method for treating Chd7 deficiency.
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27
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Counter SA, Nikkhou S, Brené S, Damberg P, Sierakowiak A, Klason T, Berglin CE, Laurell G. MRI evidence of endolymphatic impermeability to the gadolinium molecule in the in vivo mouse inner ear at 9.4 tesla. Open Neuroimag J 2013; 7:27-31. [PMID: 23894262 PMCID: PMC3722534 DOI: 10.2174/1874440001307010027] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Revised: 06/03/2013] [Accepted: 06/03/2013] [Indexed: 11/22/2022] Open
Abstract
OBJECTIVE Previous in vivo experimental magnetic resonance imaging (MRI) investigations of the mammalian inner ear at 4.7 Tesla have indicated that intravenously injected gadolinium (Gd) penetrates the perilymphatic labyrinth, but not the endolymphatic membranous labyrinth. In the present study, high field MRI at 9.4T was used to visualize the in vivo mouse vestibulo-cochlea system, and to determine whether the endolymphatic system is permeable to a Gd complex. METHODS A 9.4 T Varian magnet equipped with a 12 cm inner diameter gradient system with maximum gradient strength of 600 mT/m, a millipede coil (Varian design) and a Gd contrast agent were used for image acquisition in the normal C57 BL-6 mouse. RESULTS High-resolution 2D and 3D images of the mouse cochlea were acquired within 80 minutes following intravenous injection of Gd. Gd initially permeated the perilymphatic scala tympani and scala vestibuli, and permitted visualization of both cochlear turns from base to apex. The superior, inferior and lateral semicircular canals were subsequently visualized in 3 planes. The membranous endolymphatic labyrinth was impermeable to intravenously injected Gd, and thus showed no apparent uptake of Gd at 9.4T. CONCLUSION The 9.4T field strength MRI permitted acquisition of high resolution images of anatomical and physiological features of the normal, wild type mouse perilymphatic inner ear in vivo, and provided further evidence that the endolymphatic system is impermeable to intravenously injected Gd.
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Affiliation(s)
- S Allen Counter
- Neurology Department, Harvard University Biological Laboratories, Cambridge, MA 02138,USA
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28
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Corsten-Janssen N, Saitta SC, Hoefsloot LH, McDonald-McGinn DM, Driscoll DA, Derks R, Dickinson KA, Kerstjens-Frederikse WS, Emanuel BS, Zackai EH, van Ravenswaaij-Arts CMA. More Clinical Overlap between 22q11.2 Deletion Syndrome and CHARGE Syndrome than Often Anticipated. Mol Syndromol 2013; 4:235-45. [PMID: 23885230 DOI: 10.1159/000351127] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/27/2013] [Indexed: 12/15/2022] Open
Abstract
CHARGE (coloboma, heart defects, atresia of choanae, retardation of growth and development, genital hypoplasia, and ear abnormalities) and 22q11.2 deletion syndromes are variable, congenital malformation syndromes that show considerable phenotypic overlap. We further explored this clinical overlap and proposed recommendations for the genetic diagnosis of both syndromes. We described 2 patients clinically diagnosed with CHARGE syndrome, who were found to carry a 22q11.2 deletion, and searched the literature for more cases. In addition, we screened our cohort of CHD7 mutation carriers (n = 802) for typical 22q11.2 deletion features and studied CHD7 in 20 patients with phenotypically 22q11.2 deletion syndrome but without haploinsufficiency of TBX1. In total, we identified 5 patients with a clinical diagnosis of CHARGE syndrome and a proven 22q11.2 deletion. Typical 22q11.2 deletion features were found in 30 patients (30/802, 3.7%) of our CHD7 mutation-positive cohort. We found truncating CHD7 mutations in 5/20 patients with phenotypically 22q11.2 deletion syndrome. Differentiating between CHARGE and 22q11.2 deletion syndromes can be challenging. CHD7 and TBX1 probably share a molecular pathway or have common target genes in affected organs. We strongly recommend performing CHD7 analysis in patients with a 22q11.2 deletion phenotype without TBX1 haploinsufficiency and conversely, performing a genome-wide array in CHARGE syndrome patients without a CHD7 mutation.
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Affiliation(s)
- N Corsten-Janssen
- University of Groningen, University Medical Centre Groningen, Department of Genetics, Groningen, The Netherlands
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29
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Tian C, Yu H, Yang B, Han F, Zheng Y, Bartels CF, Schelling D, Arnold JE, Scacheri PC, Zheng QY. Otitis media in a new mouse model for CHARGE syndrome with a deletion in the Chd7 gene. PLoS One 2012; 7:e34944. [PMID: 22539951 PMCID: PMC3335168 DOI: 10.1371/journal.pone.0034944] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Accepted: 03/11/2012] [Indexed: 11/17/2022] Open
Abstract
Otitis media is a middle ear disease common in children under three years old. Otitis media can occur in normal individuals with no other symptoms or syndromes, but it is often seen in individuals clinically diagnosed with genetic diseases such as CHARGE syndrome, a complex genetic disease caused by mutation in the Chd7 gene and characterized by multiple birth defects. Although otitis media is common in human CHARGE syndrome patients, it has not been reported in mouse models of CHARGE syndrome. In this study, we report a mouse model with a spontaneous deletion mutation in the Chd7 gene and with chronic otitis media of early onset age accompanied by hearing loss. These mice also exhibit morphological alteration in the Eustachian tubes, dysregulation of epithelial proliferation, and decreased density of middle ear cilia. Gene expression profiling revealed up-regulation of Muc5ac, Muc5b and Tgf-β1 transcripts, the products of which are involved in mucin production and TGF pathway regulation. This is the first mouse model of CHARGE syndrome reported to show otitis media with effusion and it will be valuable for studying the etiology of otitis media and other symptoms in CHARGE syndrome.
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Affiliation(s)
- Cong Tian
- Department of Otolaryngology-Head and Neck Surgery, University Hospitals of Cleveland, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
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30
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Kopecky B, Johnson S, Schmitz H, Santi P, Fritzsch B. Scanning thin-sheet laser imaging microscopy elucidates details on mouse ear development. Dev Dyn 2012; 241:465-80. [PMID: 22271591 PMCID: PMC5010664 DOI: 10.1002/dvdy.23736] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/02/2012] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND The mammalian inner ear is transformed from a flat placode into a three-dimensional (3D) structure with six sensory epithelia that allow for the perception of sound and both linear and angular acceleration. While hearing and balance problems are typically considered to be adult onset diseases, they may arise as a developmental perturbation to the developing ear. Future prevention of hearing or balance loss requires an understanding of how closely genetic mutations in model organisms reflect the human case, necessitating an objective multidimensional comparison of mouse ears with human ears that have comparable mutations in the same gene. RESULTS Here, we present improved 3D analyses of normal murine ears during embryonic development using optical sections obtained through Thin-Sheet Laser Imaging Microscopy. We chronicle the transformation of an undifferentiated otic vesicle between mouse embryonic day 11.5 to a fully differentiated inner ear at postnatal day 15. CONCLUSIONS Our analysis of ear development provides new insights into ear development, enables unique perspectives into the complex development of the ear, and allows for the first full quantification of volumetric and linear aspects of ear growth. Our data provide the framework for future analysis of mutant phenotypes that are currently under-appreciated using only two dimensional renderings.
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Affiliation(s)
- Benjamin Kopecky
- Department of Biology, University of Iowa, Iowa City, Iowa 52242, USA.
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