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Li X, Morgan C, Nadar‐Ponniah PT, Kolanus W, Doetzlhofer A. TRIM71 reactivation enhances the mitotic and hair cell-forming potential of cochlear supporting cells. EMBO Rep 2023; 24:e56562. [PMID: 37492931 PMCID: PMC10481673 DOI: 10.15252/embr.202256562] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Revised: 06/27/2023] [Accepted: 07/04/2023] [Indexed: 07/27/2023] Open
Abstract
Cochlear hair cell loss is a leading cause of deafness in humans. Neighboring supporting cells have some capacity to regenerate hair cells. However, their regenerative potential sharply declines as supporting cells undergo maturation (postnatal day 5 in mice). We recently reported that reactivation of the RNA-binding protein LIN28B restores the hair cell-regenerative potential of P5 cochlear supporting cells. Here, we identify the LIN28B target Trim71 as a novel and equally potent enhancer of supporting cell plasticity. TRIM71 is a critical regulator of stem cell behavior and cell reprogramming; however, its role in cell regeneration is poorly understood. Employing an organoid-based assay, we show that TRIM71 re-expression increases the mitotic and hair cell-forming potential of P5 cochlear supporting cells by facilitating their de-differentiation into progenitor-like cells. Our mechanistic work indicates that TRIM71's RNA-binding activity is essential for such ability, and our transcriptomic analysis identifies gene modules that are linked to TRIM71 and LIN28B-mediated supporting cell reprogramming. Furthermore, our study uncovers that the TRIM71-LIN28B target Hmga2 is essential for supporting cell self-renewal and hair cell formation.
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Affiliation(s)
- Xiao‐Jun Li
- The Solomon H. Snyder Department of NeuroscienceJohns Hopkins University School of MedicineBaltimoreMDUSA
- Present address:
Frontier Institute of Science and TechnologyXi'an Jiaotong UniversityXi'an710054China
| | - Charles Morgan
- The Solomon H. Snyder Department of NeuroscienceJohns Hopkins University School of MedicineBaltimoreMDUSA
| | - Prathamesh T Nadar‐Ponniah
- The Solomon H. Snyder Department of NeuroscienceJohns Hopkins University School of MedicineBaltimoreMDUSA
| | - Waldemar Kolanus
- Molecular Immunology and Cell Biology, Life & Medical Sciences Institute (LIMES)University of BonnBonnGermany
| | - Angelika Doetzlhofer
- The Solomon H. Snyder Department of NeuroscienceJohns Hopkins University School of MedicineBaltimoreMDUSA
- Department of Otolaryngology and Center for Hearing and BalanceJohns Hopkins University School of MedicineBaltimoreMDUSA
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2
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Li XJ, Morgan C, Nadar-Ponniah PT, Kolanus W, Doetzlhofer A. Reactivation of the progenitor gene Trim71 enhances the mitotic and hair cell-forming potential of cochlear supporting cells. bioRxiv 2023:2023.01.12.523802. [PMID: 36711735 PMCID: PMC9882147 DOI: 10.1101/2023.01.12.523802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Cochlear hair cell loss is a leading cause of deafness in humans. Neighboring supporting cells have some capacity to regenerate hair cells. However, their regenerative potential sharply declines as supporting cells undergo maturation (postnatal day 5 in mice). We recently reported that reactivation of the RNA-binding protein LIN28B restores the hair cell-regenerative potential of P5 cochlear supporting cells. Here, we identify the LIN28B target Trim71 as a novel and equally potent enhancer of supporting cell plasticity. TRIM71 is a critical regulator of stem cell behavior and cell reprogramming, however, its role in cell regeneration is poorly understood. Employing an organoid-based assay, we show that TRIM71 reactivation increases the mitotic and hair cell-forming potential of P5 cochlear supporting cells by facilitating their de-differentiation into progenitor-like cells. Our mechanistic work indicates that TRIM71’s RNA-binding activity is essential for such ability, and our transcriptomic analysis identifies gene modules that are linked to TRIM71 and LIN28B-mediated supporting cell reprogramming. Furthermore, our study uncovers that the TRIM71-LIN28B target Hmga2 is essential for supporting cell self-renewal and hair cell formation.
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3
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Duy PQ, Weise SC, Marini C, Li XJ, Liang D, Dahl PJ, Ma S, Spajic A, Dong W, Juusola J, Kiziltug E, Kundishora AJ, Koundal S, Pedram MZ, Torres-Fernández LA, Händler K, De Domenico E, Becker M, Ulas T, Juranek SA, Cuevas E, Hao LT, Jux B, Sousa AMM, Liu F, Kim SK, Li M, Yang Y, Takeo Y, Duque A, Nelson-Williams C, Ha Y, Selvaganesan K, Robert SM, Singh AK, Allington G, Furey CG, Timberlake AT, Reeves BC, Smith H, Dunbar A, DeSpenza T, Goto J, Marlier A, Moreno-De-Luca A, Yu X, Butler WE, Carter BS, Lake EMR, Constable RT, Rakic P, Lin H, Deniz E, Benveniste H, Malvankar NS, Estrada-Veras JI, Walsh CA, Alper SL, Schultze JL, Paeschke K, Doetzlhofer A, Wulczyn FG, Jin SC, Lifton RP, Sestan N, Kolanus W, Kahle KT. Impaired neurogenesis alters brain biomechanics in a neuroprogenitor-based genetic subtype of congenital hydrocephalus. Nat Neurosci 2022; 25:458-473. [PMID: 35379995 PMCID: PMC9664907 DOI: 10.1038/s41593-022-01043-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 02/28/2022] [Indexed: 01/16/2023]
Abstract
Hydrocephalus, characterized by cerebral ventricular dilatation, is routinely attributed to primary defects in cerebrospinal fluid (CSF) homeostasis. This fosters CSF shunting as the leading reason for brain surgery in children despite considerable disease heterogeneity. In this study, by integrating human brain transcriptomics with whole-exome sequencing of 483 patients with congenital hydrocephalus (CH), we found convergence of CH risk genes in embryonic neuroepithelial stem cells. Of all CH risk genes, TRIM71/lin-41 harbors the most de novo mutations and is most specifically expressed in neuroepithelial cells. Mice harboring neuroepithelial cell-specific Trim71 deletion or CH-specific Trim71 mutation exhibit prenatal hydrocephalus. CH mutations disrupt TRIM71 binding to its RNA targets, causing premature neuroepithelial cell differentiation and reduced neurogenesis. Cortical hypoplasia leads to a hypercompliant cortex and secondary ventricular enlargement without primary defects in CSF circulation. These data highlight the importance of precisely regulated neuroepithelial cell fate for normal brain-CSF biomechanics and support a clinically relevant neuroprogenitor-based paradigm of CH.
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Affiliation(s)
- Phan Q Duy
- Department of Neuroscience and Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT, USA.,Department of Neurosurgery, Yale University School of Medicine, New Haven, CT, USA.,Medical Scientist Training Program, Yale University School of Medicine, New Haven, CT, USA
| | - Stefan C Weise
- Molecular Immunology and Cell Biology, Life & Medical Sciences Institute (LIMES), University of Bonn, Bonn, Germany
| | - Claudia Marini
- Institute for Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Xiao-Jun Li
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,Center for Hearing and Balance, Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Dan Liang
- Department of Neuroscience and Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT, USA
| | - Peter J Dahl
- Microbial Sciences Institute, Yale University, West Haven, CT, USA.,Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
| | - Shaojie Ma
- Department of Neuroscience and Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT, USA
| | - Ana Spajic
- Department of Neuroscience and Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT, USA
| | - Weilai Dong
- Laboratory of Human Genetics and Genomics, The Rockefeller University, New York, NY, USA
| | | | - Emre Kiziltug
- Department of Neurosurgery, Yale University School of Medicine, New Haven, CT, USA
| | - Adam J Kundishora
- Department of Neurosurgery, Yale University School of Medicine, New Haven, CT, USA
| | - Sunil Koundal
- Department of Anesthesiology, Yale University School of Medicine, New Haven, CT, USA
| | - Maysam Z Pedram
- Department of Anesthesiology, Yale University School of Medicine, New Haven, CT, USA
| | - Lucia A Torres-Fernández
- Molecular Immunology and Cell Biology, Life & Medical Sciences Institute (LIMES), University of Bonn, Bonn, Germany
| | - Kristian Händler
- Systems Medicine, Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Bonn, Germany.,Genomics and Immunoregulation, Life & Medical Sciences (LIMES) Institute, University of Bonn, Bonn, Germany.,Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE). PRECISE Platform for Genomics and Epigenomics at DZNE and University of Bonn, Bonn, Germany
| | - Elena De Domenico
- Systems Medicine, Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Bonn, Germany.,Genomics and Immunoregulation, Life & Medical Sciences (LIMES) Institute, University of Bonn, Bonn, Germany.,Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE). PRECISE Platform for Genomics and Epigenomics at DZNE and University of Bonn, Bonn, Germany
| | - Matthias Becker
- Systems Medicine, Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Bonn, Germany.,Genomics and Immunoregulation, Life & Medical Sciences (LIMES) Institute, University of Bonn, Bonn, Germany.,Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE). PRECISE Platform for Genomics and Epigenomics at DZNE and University of Bonn, Bonn, Germany
| | - Thomas Ulas
- Systems Medicine, Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Bonn, Germany.,Genomics and Immunoregulation, Life & Medical Sciences (LIMES) Institute, University of Bonn, Bonn, Germany.,Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE). PRECISE Platform for Genomics and Epigenomics at DZNE and University of Bonn, Bonn, Germany
| | - Stefan A Juranek
- Department of Oncology, Hematology and Rheumatology, University Hospital Bonn, Bonn, Germany
| | - Elisa Cuevas
- Stem Cells and Regenerative Medicine Section, University College London Great Ormond Street Institute of Child Health, London, UK
| | - Le Thi Hao
- Department of Neurosurgery, Yale University School of Medicine, New Haven, CT, USA
| | - Bettina Jux
- Molecular Immunology and Cell Biology, Life & Medical Sciences Institute (LIMES), University of Bonn, Bonn, Germany
| | - André M M Sousa
- Department of Neuroscience and Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT, USA
| | - Fuchen Liu
- Department of Neuroscience and Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT, USA
| | - Suel-Kee Kim
- Department of Neuroscience and Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT, USA
| | - Mingfeng Li
- Department of Neuroscience and Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT, USA
| | - Yiying Yang
- Yale Stem Cell Center, Yale University School of Medicine, New Haven, CT, USA
| | - Yutaka Takeo
- Department of Neurosurgery, Yale University School of Medicine, New Haven, CT, USA
| | - Alvaro Duque
- Department of Neuroscience and Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT, USA
| | | | - Yonghyun Ha
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT, USA
| | - Kartiga Selvaganesan
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT, USA
| | - Stephanie M Robert
- Department of Neurosurgery, Yale University School of Medicine, New Haven, CT, USA
| | - Amrita K Singh
- Department of Neurosurgery, Yale University School of Medicine, New Haven, CT, USA
| | - Garrett Allington
- Department of Neurosurgery, Yale University School of Medicine, New Haven, CT, USA
| | - Charuta G Furey
- Department of Neurosurgery, Yale University School of Medicine, New Haven, CT, USA
| | - Andrew T Timberlake
- Department of Genetics, Yale University School of Medicine, New Haven, CT, USA
| | - Benjamin C Reeves
- Department of Neurosurgery, Yale University School of Medicine, New Haven, CT, USA
| | - Hannah Smith
- Department of Neurosurgery, Yale University School of Medicine, New Haven, CT, USA
| | - Ashley Dunbar
- Department of Neurosurgery, Yale University School of Medicine, New Haven, CT, USA
| | - Tyrone DeSpenza
- Department of Neurosurgery, Yale University School of Medicine, New Haven, CT, USA
| | - June Goto
- Division of Pediatric Neurosurgery, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Arnaud Marlier
- Department of Neurosurgery, Yale University School of Medicine, New Haven, CT, USA
| | - Andres Moreno-De-Luca
- Department of Radiology, Autism & Developmental Medicine Institute, Genomic Medicine Institute, Geisinger, Danville, PA, USA
| | - Xin Yu
- Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - William E Butler
- Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Bob S Carter
- Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Evelyn M R Lake
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT, USA
| | - R Todd Constable
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT, USA
| | - Pasko Rakic
- Department of Neuroscience and Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT, USA
| | - Haifan Lin
- Yale Stem Cell Center, Yale University School of Medicine, New Haven, CT, USA
| | - Engin Deniz
- Department of Pediatrics, Yale University School of Medicine, New Haven, CT, USA
| | - Helene Benveniste
- Department of Anesthesiology, Yale University School of Medicine, New Haven, CT, USA
| | - Nikhil S Malvankar
- Microbial Sciences Institute, Yale University, West Haven, CT, USA.,Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
| | - Juvianee I Estrada-Veras
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, USA.,Pediatric Subspecialty Genetics Walter Reed National Military Medical Center, Bethesda, MD, USA.,Murtha Cancer Center/Research Program, Department of Surgery, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
| | - Christopher A Walsh
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Department of Pediatrics, and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA, USA.,Departments of Pediatrics and Neurology, Harvard Medical School, Boston, MA, USA.,Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Seth L Alper
- Broad Institute of MIT and Harvard, Cambridge, MA, USA.,Division of Nephrology and Vascular Biology Research Center, Beth Israel Deaconess Medical Center and Department of Medicine, Harvard Medical School, Boston, MA, USA
| | - Joachim L Schultze
- Systems Medicine, Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Bonn, Germany.,Genomics and Immunoregulation, Life & Medical Sciences (LIMES) Institute, University of Bonn, Bonn, Germany.,Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE). PRECISE Platform for Genomics and Epigenomics at DZNE and University of Bonn, Bonn, Germany
| | - Katrin Paeschke
- Department of Oncology, Hematology and Rheumatology, University Hospital Bonn, Bonn, Germany
| | - Angelika Doetzlhofer
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,Center for Hearing and Balance, Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - F Gregory Wulczyn
- Institute for Cell Biology and Neurobiology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Sheng Chih Jin
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA
| | - Richard P Lifton
- Laboratory of Human Genetics and Genomics, The Rockefeller University, New York, NY, USA
| | - Nenad Sestan
- Department of Neuroscience and Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, CT, USA
| | - Waldemar Kolanus
- Molecular Immunology and Cell Biology, Life & Medical Sciences Institute (LIMES), University of Bonn, Bonn, Germany
| | - Kristopher T Kahle
- Department of Neurosurgery, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA. .,Division of Genetics and Genomics, Manton Center for Orphan Disease Research, Department of Pediatrics, and Howard Hughes Medical Institute, Boston Children's Hospital, Boston, MA, USA. .,Broad Institute of MIT and Harvard, Cambridge, MA, USA. .,Harvard Center for Hydrocephalus and Neurodevelopmental Disorders, Massachusetts General Hospital, Boston, MA, USA.
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4
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Li XJ, Morgan C, Goff LA, Doetzlhofer A. Follistatin promotes LIN28B-mediated supporting cell reprogramming and hair cell regeneration in the murine cochlea. Sci Adv 2022; 8:eabj7651. [PMID: 35148175 PMCID: PMC8836811 DOI: 10.1126/sciadv.abj7651] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Accepted: 12/18/2021] [Indexed: 05/27/2023]
Abstract
Hair cell (HC) loss within the inner ear cochlea is a leading cause for deafness in humans. Before the onset of hearing, immature supporting cells (SCs) in neonatal mice have some limited capacity for HC regeneration. Here, we show that in organoid culture, transient activation of the progenitor-specific RNA binding protein LIN28B and Activin antagonist follistatin (FST) enhances regenerative competence of maturing/mature cochlear SCs by reprogramming them into progenitor-like cells. Transcriptome profiling and mechanistic studies reveal that LIN28B drives SC reprogramming, while FST is required to counterbalance hyperactivation of transforming growth factor-β-type signaling by LIN28B. Last, we show that LIN28B and FST coactivation enhances spontaneous cochlear HC regeneration in neonatal mice and that LIN28B may be part of an endogenous repair mechanism that primes SCs for HC regeneration. These findings indicate that SC dedifferentiation is critical for HC regeneration and identify LIN28B and FST as main regulators.
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Affiliation(s)
- Xiao-Jun Li
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Charles Morgan
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Loyal A. Goff
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- McKusick-Nathans Institute for Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Kavli Neuroscience Discovery Institute, Johns Hopkins University, 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 and Center for Hearing and Balance, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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5
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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: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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6
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Prajapati-DiNubila M, Benito-Gonzalez A, Golden EJ, Zhang S, Doetzlhofer A. A counter gradient of Activin A and follistatin instructs the timing of hair cell differentiation in the murine cochlea. eLife 2019; 8:47613. [PMID: 31187730 PMCID: PMC6561706 DOI: 10.7554/elife.47613] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 05/27/2019] [Indexed: 12/14/2022] Open
Abstract
The mammalian auditory sensory epithelium has one of the most stereotyped cellular patterns known in vertebrates. Mechano-sensory hair cells are arranged in precise rows, with one row of inner and three rows of outer hair cells spanning the length of the spiral-shaped sensory epithelium. Aiding such precise cellular patterning, differentiation of the auditory sensory epithelium is precisely timed and follows a steep longitudinal gradient. The molecular signals that promote auditory sensory differentiation and instruct its graded pattern are largely unknown. Here, we identify Activin A and its antagonist follistatin as key regulators of hair cell differentiation and show, using mouse genetic approaches, that a local gradient of Activin A signaling within the auditory sensory epithelium times the longitudinal gradient of hair cell differentiation. Furthermore, we provide evidence that Activin-type signaling regulates a radial gradient of terminal mitosis within the auditory sensory epithelium, which constitutes a novel mechanism for limiting the number of inner hair cells being produced.
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Affiliation(s)
- Meenakshi Prajapati-DiNubila
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, United States.,Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, United States
| | - Ana Benito-Gonzalez
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, United States.,Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, United States
| | - Erin Jennifer Golden
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, United States.,Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, United States
| | - Shuran Zhang
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, United States.,Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, United States
| | - Angelika Doetzlhofer
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, United States.,Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, United States
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7
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Basch ML, Brown RM, Jen HI, Semerci F, Depreux F, Edlund RK, Zhang H, Norton CR, Gridley T, Cole SE, Doetzlhofer A, Maletic-Savatic M, Segil N, Groves AK. Fine-tuning of Notch signaling sets the boundary of the organ of Corti and establishes sensory cell fates. eLife 2016; 5:19921. [PMID: 27966429 PMCID: PMC5215100 DOI: 10.7554/elife.19921] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 12/12/2016] [Indexed: 01/08/2023] Open
Abstract
The signals that induce the organ of Corti and define its boundaries in the cochlea are poorly understood. We show that two Notch modifiers, Lfng and Mfng, are transiently expressed precisely at the neural boundary of the organ of Corti. Cre-Lox fate mapping shows this region gives rise to inner hair cells and their associated inner phalangeal cells. Mutation of Lfng and Mfng disrupts this boundary, producing unexpected duplications of inner hair cells and inner phalangeal cells. This phenotype is mimicked by other mouse mutants or pharmacological treatments that lower but not abolish Notch signaling. However, strong disruption of Notch signaling causes a very different result, generating many ectopic hair cells at the expense of inner phalangeal cells. Our results show that Notch signaling is finely calibrated in the cochlea to produce precisely tuned levels of signaling that first set the boundary of the organ of Corti and later regulate hair cell development. DOI:http://dx.doi.org/10.7554/eLife.19921.001
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Affiliation(s)
- Martin L Basch
- Department of Neuroscience, Baylor College of Medicine, Houston, United States
| | - Rogers M Brown
- Program in Developmental Biology, Baylor College of Medicine, Houston, United States
| | - Hsin-I Jen
- Program in Developmental Biology, Baylor College of Medicine, Houston, United States
| | - Fatih Semerci
- Program in Developmental Biology, Baylor College of Medicine, Houston, United States
| | - Frederic Depreux
- Department of Cell Biology and Anatomy, Rosalind Franklin University of Medicine and Science, Chicago, United States
| | - Renée K Edlund
- Program in Developmental Biology, Baylor College of Medicine, Houston, United States
| | - Hongyuan Zhang
- Department of Neuroscience, Baylor College of Medicine, Houston, United States
| | | | - Thomas Gridley
- Maine Medical Center Research Institute, Scarborough, United States
| | - Susan E Cole
- Department of Molecular Genetics, The Ohio State University, Columbus, United States
| | - Angelika Doetzlhofer
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, School of Medicine, Baltimore, United States
| | - Mirjana Maletic-Savatic
- Department of Neuroscience, Baylor College of Medicine, Houston, United States.,Program in Developmental Biology, Baylor College of Medicine, Houston, United States.,Department of Pediatrics, Baylor College of Medicine, Houston, United States.,Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, United States
| | - Neil Segil
- Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine, University of Southern California, Los Angeles, United States
| | - Andrew K Groves
- Department of Neuroscience, Baylor College of Medicine, Houston, United States.,Program in Developmental Biology, Baylor College of Medicine, Houston, United States.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
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8
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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 2016; 65:69-79. [PMID: 27836639 DOI: 10.1016/j.semcdb.2016.11.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [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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9
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Abstract
Chicken embryos are ideal model systems for studying embryonic development as manipulations of gene function can be conducted with relative ease in ovo. The inner ear auditory sensory organ is critical for our ability to hear. It houses a highly specialized sensory epithelium that consists of mechano-transducing hair cells (HCs) and surrounding glial-like supporting cells (SCs). Despite structural differences in the auditory organs, molecular mechanisms regulating the development of the auditory organ are evolutionarily conserved between mammals and aves. In ovo electroporation is largely limited to early stages at E1 - E3. Due to the relative late development of the auditory organ at E5, manipulations of the auditory organ by in ovo electroporation past E3 are difficult due to the advanced development of the chicken embryo at later stages. The method presented here is a transient gene transfer method for targeting genes of interest at stage E4 - E4.5 in the developing chicken auditory sensory organ via in ovo micro-electroporation. This method is applicable for gain- and loss-of-functions with conventional plasmid DNA-based expression vectors and can be combined with in ovo cell proliferation assay by adding EdU (5-ethynyl-2´-deoxyuridine) to the whole embryo at the time of electroporation. The use of green or red fluorescent protein (GFP or RFP) expression plasmids allows the experimenter to quickly determine whether the electroporation successfully targeted the auditory portion of the developing inner ear. In this method paper, representative examples of GFP electroporated specimens are illustrated; embryos were harvested 18 - 96 hr after electroporation and targeting of GFP to the pro-sensory area of the auditory organ was confirmed by RNA in situ hybridization. The method paper also provides an optimized protocol for the use of the thymidine analog EdU to analyze cell proliferation; an example of an EdU based cell proliferation assay that combines immuno-labeling and click EdU chemistry is provided.
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Affiliation(s)
- Lale Evsen
- The Solomon H. Snyder Department of Neuroscience, The Center for Sensory Biology, The Johns Hopkins University, School of Medicine
| | - Angelika Doetzlhofer
- The Solomon H. Snyder Department of Neuroscience, The Center for Sensory Biology, The Johns Hopkins University, School of Medicine;
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10
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Campbell DP, Chrysostomou E, Doetzlhofer A. Canonical Notch signaling plays an instructive role in auditory supporting cell development. Sci Rep 2016; 6:19484. [PMID: 26786414 PMCID: PMC4726253 DOI: 10.1038/srep19484] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 12/14/2015] [Indexed: 02/07/2023] Open
Abstract
The auditory sensory epithelium, composed of mechano-sensory hair cells (HCs) and highly specialized glial-like supporting cells (SCs), is critical for our ability to detect sound. SCs provide structural and functional support to HCs and play an essential role in cochlear development, homeostasis and repair. Despite their importance, however, surprisingly little is known about the molecular mechanisms guiding SC differentiation. Here, we provide evidence that in addition to its well-characterized inhibitory function, canonical Notch signaling plays a positive, instructive role in the differentiation of SCs. Using γ-secretase inhibitor DAPT to acutely block canonical Notch signaling, we identified a cohort of Notch-regulated SC-specific genes, with diverse functions in cell signaling, cell differentiation, neuronal innervation and synaptogenesis. We validated the newly identified Notch-regulated genes in vivo using genetic gain (Emx2Cre/+; Rosa26N1ICD/+) and loss-of-function approaches (Emx2Cre/+; Rosa26DnMAML1/+). Furthermore, we demonstrate that Notch over-activation in the differentiating murine cochlea (Emx2Cre/+; Rosa26N1ICD/+) actively promotes a SC-specific gene expression program. Finally, we show that outer SCs –so called Deiters’ cells are selectively lost by prolonged reduction (Emx2Cre/+; Rosa26DnMAML1/+/+) or abolishment of canonical Notch signaling (Fgfr3-iCreER; Rbpj−/Δ), indicating a critical role for Notch signaling in Deiters’ cell development.
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Affiliation(s)
- Dean P Campbell
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, School of Medicine Baltimore, MD 21205, USA.,Center for Sensory Biology, Johns Hopkins University, School of Medicine Baltimore, MD 21205, USA
| | - Elena Chrysostomou
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, School of Medicine Baltimore, MD 21205, USA.,Center for Sensory Biology, Johns Hopkins University, School of Medicine Baltimore, MD 21205, USA
| | - Angelika Doetzlhofer
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, School of Medicine Baltimore, MD 21205, USA.,Center for Sensory Biology, Johns Hopkins University, School of Medicine Baltimore, MD 21205, USA
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11
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Abstract
Proper tissue development requires strict coordination of proliferation, growth, and differentiation. Strict coordination is particularly important for the auditory sensory epithelium, where deviations from the normal spatial and temporal pattern of auditory progenitor cell (prosensory cell) proliferation and differentiation result in abnormal cellular organization and, thus, auditory dysfunction. The molecular mechanisms involved in the timing and coordination of auditory prosensory proliferation and differentiation are poorly understood. Here we identify the RNA-binding protein LIN28B as a critical regulator of developmental timing in the murine cochlea. We show that Lin28b and its opposing let-7 miRNAs are differentially expressed in the auditory sensory lineage, with Lin28b being highly expressed in undifferentiated prosensory cells and let-7 miRNAs being highly expressed in their progeny-hair cells (HCs) and supporting cells (SCs). Using recently developed transgenic mouse models for LIN28B and let-7g, we demonstrate that prolonged LIN28B expression delays prosensory cell cycle withdrawal and differentiation, resulting in HC and SC patterning and maturation defects. Surprisingly, let-7g overexpression, although capable of inducing premature prosensory cell cycle exit, failed to induce premature HC differentiation, suggesting that LIN28B's functional role in the timing of differentiation uses let-7 independent mechanisms. Finally, we demonstrate that overexpression of LIN28B or let-7g can significantly alter the postnatal production of HCs in response to Notch inhibition; LIN28B has a positive effect on HC production, whereas let-7 antagonizes this process. Together, these results implicate a key role for the LIN28B/let-7 axis in regulating postnatal SC plasticity.
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Affiliation(s)
- Erin J Golden
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205; Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Ana Benito-Gonzalez
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205; Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Angelika Doetzlhofer
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205; Center for Sensory Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205
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12
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Korrapati S, Roux I, Glowatzki E, Doetzlhofer A. Notch signaling limits supporting cell plasticity in the hair cell-damaged early postnatal murine cochlea. PLoS One 2013; 8:e73276. [PMID: 24023676 PMCID: PMC3758270 DOI: 10.1371/journal.pone.0073276] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Accepted: 07/18/2013] [Indexed: 12/02/2022] Open
Abstract
In mammals, auditory hair cells are generated only during embryonic development and loss or damage to hair cells is permanent. However, in non-mammalian vertebrate species, such as birds, neighboring glia-like supporting cells regenerate auditory hair cells by both mitotic and non-mitotic mechanisms. Based on work in intact cochlear tissue, it is thought that Notch signaling might restrict supporting cell plasticity in the mammalian cochlea. However, it is unresolved how Notch signaling functions in the hair cell-damaged cochlea and the molecular and cellular changes induced in supporting cells in response to hair cell trauma are poorly understood. Here we show that gentamicin-induced hair cell loss in early postnatal mouse cochlear tissue induces rapid morphological changes in supporting cells, which facilitate the sealing of gaps left by dying hair cells. Moreover, we provide evidence that Notch signaling is active in the hair cell damaged cochlea and identify Hes1, Hey1, Hey2, HeyL, and Sox2 as targets and potential Notch effectors of this hair cell-independent mechanism of Notch signaling. Using Cre/loxP based labeling system we demonstrate that inhibition of Notch signaling with a γ- secretase inhibitor (GSI) results in the trans-differentiation of supporting cells into hair cell-like cells. Moreover, we show that these hair cell-like cells, generated by supporting cells have molecular, cellular, and basic electrophysiological properties similar to immature hair cells rather than supporting cells. Lastly, we show that the vast majority of these newly generated hair cell-like cells express the outer hair cell specific motor protein prestin.
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Affiliation(s)
- Soumya Korrapati
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
- Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
- Center for Hearing and Balance, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
| | - Isabelle Roux
- Department of Otolaryngology, Head and Neck Surgery, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
- Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
- Center for Hearing and Balance, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
| | - Elisabeth Glowatzki
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
- Department of Otolaryngology, Head and Neck Surgery, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
- Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
- Center for Hearing and Balance, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
| | - Angelika Doetzlhofer
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
- Department of Otolaryngology, Head and Neck Surgery, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
- Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
- Center for Hearing and Balance, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
- * E-mail:
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13
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Doetzlhofer A, Basch ML, Ohyama T, Gessler M, Groves AK, Segil N. Hey2 regulation by FGF provides a Notch-independent mechanism for maintaining pillar cell fate in the organ of Corti. Dev Cell 2009; 16:58-69. [PMID: 19154718 DOI: 10.1016/j.devcel.2008.11.008] [Citation(s) in RCA: 208] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2008] [Revised: 10/15/2008] [Accepted: 11/14/2008] [Indexed: 02/06/2023]
Abstract
The organ of Corti, the auditory organ of the inner ear, contains two types of sensory hair cells and at least seven types of supporting cells. Most of these supporting cell types rely on Notch-dependent expression of Hes/Hey transcription factors to maintain the supporting cell fate. Here, we show that Notch signaling is not necessary for the differentiation and maintenance of pillar cell fate, that pillar cells are distinguished by Hey2 expression, and that-unlike other Hes/Hey factors-Hey2 expression is Notch independent. Hey2 is activated by FGF and blocks hair cell differentiation, whereas mutation of Hey2 leaves pillar cells sensitive to the loss of Notch signaling and allows them to differentiate as hair cells. We speculate that co-option of FGF signaling to render Hey2 Notch independent also liberated pillar cells from the need for direct contact with surrounding hair cells, and enabled evolutionary remodeling of the complex cellular mosaic of the inner ear.
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Affiliation(s)
- Angelika Doetzlhofer
- Gonda Department of Cell and Molecular Biology, House Ear Institute, Los Angeles, CA 90057, USA
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14
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Laine H, Doetzlhofer A, Mantela J, Ylikoski J, Laiho M, Roussel MF, Segil N, Pirvola U. p19(Ink4d) and p21(Cip1) collaborate to maintain the postmitotic state of auditory hair cells, their codeletion leading to DNA damage and p53-mediated apoptosis. J Neurosci 2007; 27:1434-44. [PMID: 17287518 PMCID: PMC6673588 DOI: 10.1523/jneurosci.4956-06.2007] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2006] [Revised: 12/22/2006] [Accepted: 12/22/2006] [Indexed: 11/21/2022] Open
Abstract
Sensory hair cells of the auditory organ are generated during embryogenesis and remain postmitotic throughout life. Previous work has shown that inactivation of the cyclin-dependent kinase inhibitor (CKI) p19(Ink4d) leads to progressive hearing loss attributable to inappropriate DNA replication and subsequent apoptosis of hair cells. Here we show the synergistic action of another CKI, p21(Cip1), on cell cycle reactivation. The codeletion of p19(Ink4d) and p21(Cip1) triggered profuse S-phase entry of auditory hair cells during a restricted period in early postnatal life, leading to the transient appearance of supernumerary hair cells. In addition, we show that aberrant cell cycle reentry leads to activation of a DNA damage response pathway in these cells, followed by p53-mediated apoptosis. The majority of hair cells were absent in adult cochleas. These data, together with the demonstration of changing expression patterns of multiple CKIs in auditory hair cells during the stages of early postnatal maturation, show that the maintenance of the postmitotic state is an active, tissue-specific process, cooperatively regulated by several CKIs, and is critical for the lifelong survival of these sensory cells.
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Affiliation(s)
| | - Angelika Doetzlhofer
- Gonda Department of Cell and Molecular Biology, House Ear Institute, Los Angeles, California 90057, and
| | | | | | - Marikki Laiho
- Molecular Cancer Biology Program, Biomedicum Helsinki, University of Helsinki, 00014 Helsinki, Finland
| | - Martine F. Roussel
- Department of Tumor Biology and Genetics, St. Jude Children's Research Hospital, Memphis, Tennessee 38105
| | - Neil Segil
- Gonda Department of Cell and Molecular Biology, House Ear Institute, Los Angeles, California 90057, and
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15
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White PM, Doetzlhofer A, Lee YS, Groves AK, Segil N. Mammalian cochlear supporting cells can divide and trans-differentiate into hair cells. Nature 2006; 441:984-7. [PMID: 16791196 DOI: 10.1038/nature04849] [Citation(s) in RCA: 313] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2006] [Accepted: 04/26/2006] [Indexed: 02/06/2023]
Abstract
Sensory hair cells of the mammalian organ of Corti in the inner ear do not regenerate when lost as a consequence of injury, disease, or age-related deafness. This contrasts with other vertebrates such as birds, where the death of hair cells causes surrounding supporting cells to re-enter the cell cycle and give rise to both new hair cells and supporting cells. It is not clear whether the lack of mammalian hair cell regeneration is due to an intrinsic inability of supporting cells to divide and differentiate or to an absence or blockade of regenerative signals. Here we show that post-mitotic supporting cells purified from the postnatal mouse cochlea retain the ability to divide and trans-differentiate into new hair cells in culture. Furthermore, we show that age-dependent changes in supporting cell proliferative capacity are due in part to changes in the ability to downregulate the cyclin-dependent kinase inhibitor p27(Kip1) (also known as Cdkn1b). These results indicate that postnatal mammalian supporting cells are potential targets for therapeutic manipulation.
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Affiliation(s)
- Patricia M White
- Gonda Department of Cell and Molecular Biology, House Ear Institute, 2100 W. Third Street, Los Angeles, California 90057, USA
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16
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Doetzlhofer A, White P, Lee YS, Groves A, Segil N. Prospective identification and purification of hair cell and supporting cell progenitors from the embryonic cochlea. Brain Res 2006; 1091:282-8. [PMID: 16616734 DOI: 10.1016/j.brainres.2006.02.071] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2006] [Revised: 02/15/2006] [Accepted: 02/17/2006] [Indexed: 11/28/2022]
Abstract
Expression of the cyclin-dependent kinase inhibitor p27(Kip1) defines a post-mitotic population of cells in the embryonic mammalian cochlea that constitutes the nascent organ of Corti. Here, we describe techniques to purify these precursors using a transgenic p27/GFP reporter and fluorescence activated cell sorting (FACS). We demonstrate that these cells express other markers of the sensory lineage, such as Sox2, and when placed in dissociated cell culture differentiate as hair cells and supporting cells. The purified sensory progenitors thus obtained provide a means of studying the process of hair cell and supporting cell differentiation in vitro, as well as providing a means of analyzing the molecular and physiological properties of this unique population of cells.
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Affiliation(s)
- Angelika Doetzlhofer
- Gonda Department of Cell and Molecular Biology, House Ear Institute, 2100 West Third Street, Los Angeles, CA 90057, USA
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17
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Doetzlhofer A, White PM, Johnson JE, Segil N, Groves AK. In vitro growth and differentiation of mammalian sensory hair cell progenitors: a requirement for EGF and periotic mesenchyme. Dev Biol 2004; 272:432-47. [PMID: 15282159 DOI: 10.1016/j.ydbio.2004.05.013] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2003] [Revised: 03/22/2004] [Accepted: 05/05/2004] [Indexed: 11/19/2022]
Abstract
The sensory hair cells and supporting cells of the organ of Corti are generated by a precise program of coordinated cell division and differentiation. Since no regeneration occurs in the mature organ of Corti, loss of hair cells leads to deafness. To investigate the molecular basis of hair cell differentiation and their lack of regeneration, we have established a dissociated cell culture system in which sensory hair cells and supporting cells can be generated from mitotic precursors. By incorporating a Math1-GFP transgene expressed exclusively in hair cells, we have used this system to characterize the conditions required for the growth and differentiation of hair cells in culture. These conditions include a requirement for epidermal growth factor, as well as the presence of periotic mesenchymal cells. Lastly, we show that early postnatal cochlear tissue also contains cells that can divide and generate new sensory hair cells in vitro.
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Affiliation(s)
- Angelika Doetzlhofer
- Gonda Department of Cell and Molecular Biology, House Ear Institute, Los Angeles, CA 90057, USA
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18
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Lumpkin EA, Collisson T, Parab P, Omer-Abdalla A, Haeberle H, Chen P, Doetzlhofer A, White P, Groves A, Segil N, Johnson JE. Math1-driven GFP expression in the developing nervous system of transgenic mice. Gene Expr Patterns 2003; 3:389-95. [PMID: 12915300 DOI: 10.1016/s1567-133x(03)00089-9] [Citation(s) in RCA: 241] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Math1 is a bHLH transcription factor expressed in neural progenitor cells in multiple regions of the nervous system. Previously we identified a Math1 enhancer that directs expression of reporter genes in a Math1 specific pattern [Development 127 (2000) 1185]. We have used a portion of this enhancer to drive expression of a nuclear GFP reporter in the Math1 lineage in transgenic mice. In this transgenic mouse strain, GFP is expressed in Math1 domains in the (1). developing spinal cord in progenitors to dI1 dorsal interneurons, (2). granule-cell progenitors in the developing cerebellum, (3). Merkel cells in the skin, and (4). hair cells in the developing vestibular and auditory systems. Furthermore, non-Math1 related expression is detected that is likely due to the absence of inhibitory regulatory sequences from the transgene. These expression domains include (1). the apical ectodermal ridge in developing limbs, (2). post-mitotic cells in the developing cortex and spinal cord, (3). the dentate gyrus, (4). retina, and (5). olfactory epithelium. Because GFP marks specific neuronal cell types in living tissue, this transgenic strain is a powerful tool for future studies on the development and electrophysiological properties of distinct cell types in the central nervous system and in sensory systems.
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Affiliation(s)
- Ellen A Lumpkin
- Department of Physiology, University of California, San Francisco, 600 16th Street, San Francisco, CA 94143-2280, USA
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19
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Lagger G, Doetzlhofer A, Schuettengruber B, Haidweger E, Simboeck E, Tischler J, Chiocca S, Suske G, Rotheneder H, Wintersberger E, Seiser C. The tumor suppressor p53 and histone deacetylase 1 are antagonistic regulators of the cyclin-dependent kinase inhibitor p21/WAF1/CIP1 gene. Mol Cell Biol 2003; 23:2669-79. [PMID: 12665570 PMCID: PMC152549 DOI: 10.1128/mcb.23.8.2669-2679.2003] [Citation(s) in RCA: 167] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The cyclin-dependent kinase inhibitor p21/WAF1/CIP1 is an important regulator of cell cycle progression, senescence, and differentiation. Genotoxic stress leads to activation of the tumor suppressor p53 and subsequently to induction of p21 expression. Here we show that the tumor suppressor p53 cooperates with the transcription factor Sp1 in the activation of the p21 promoter, whereas histone deacetylase 1 (HDAC1) counteracts p53-induced transcription from the p21 gene. The p53 protein binds directly to the C terminus of Sp1, a domain which was previously shown to be required for the interaction with HDAC1. Induction of p53 in response to DNA-damaging agents resulted in the formation of p53-Sp1 complexes and simultaneous dissociation of HDAC1 from the C terminus of Sp1. Chromatin immunoprecipitation experiments demonstrated the association of HDAC1 with the p21 gene in proliferating cells. Genotoxic stress led to recruitment of p53, reduced binding of HDAC1, and hyperacetylation of core histones at the p21 promoter. Our findings show that the deacetylase HDAC1 acts as an antagonist of the tumor suppressor p53 in the regulation of the cyclin-dependent kinase inhibitor p21 and provide a basis for understanding the function of histone deacetylase inhibitors as antitumor drugs.
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Affiliation(s)
- Gerda Lagger
- Institute of Medical Biochemistry, Division of Molecular Biology, Vienna Biocenter, University of Vienna, A-1030 Vienna, Austria
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20
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Schuettengruber B, Doetzlhofer A, Kroboth K, Wintersberger E, Seiser C. Alternate activation of two divergently transcribed mouse genes from a bidirectional promoter is linked to changes in histone modification. J Biol Chem 2003; 278:1784-93. [PMID: 12411446 DOI: 10.1074/jbc.m204843200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Thymidine kinase (TK) is a growth factor-inducible enzyme that is highly expressed in proliferating mammalian cells. Expression of mouse TK mRNA is controlled by transcriptional and posttranscriptional mechanisms including antisense transcription. Here we report the identification of a novel gene that is divergently transcribed from the bidirectional TK promoter. This gene encodes kynurenine formamidase (KF), an enzyme of the tryptophan metabolism. Whereas the TK gene is induced upon interleukin-2-mediated activation of resting T cells, the KF gene becomes simultaneously repressed. The TK promoter is regulated by E2F, SP1, histone acetyltransferases, and deacetylases. The binding site for the growth-regulated transcription factor E2F is beneficial for TK promoter activity but not required for KF expression. In contrast, the SP1 binding site is crucial for transcription in both directions. Inhibition of histone deacetylases by trichostatin A leads to increased histone acetylation at the TK/KF promoter and thereby to selective activation of the TK promoter and simultaneous shut-off of KF expression. Similarly, TK gene activation by interleukin-2 is linked to histone hyperacetylation, whereas KF expression correlates with reduced histone acetylation. The KF gene is the rare example of a mammalian gene whose expression is linked to histone hypoacetylation at its promoter.
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Affiliation(s)
- Bernd Schuettengruber
- Institute of Medical Biochemistry, Division of Molecular Biology, University of Vienna, Vienna Biocenter, Dr. Bohr-Gasse 9/2, A-1030 Vienna, Austria
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Doetzlhofer A, Rotheneder H, Lagger G, Koranda M, Kurtev V, Brosch G, Wintersberger E, Seiser C. Histone deacetylase 1 can repress transcription by binding to Sp1. Mol Cell Biol 1999; 19:5504-11. [PMID: 10409740 PMCID: PMC84392 DOI: 10.1128/mcb.19.8.5504] [Citation(s) in RCA: 332] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The members of the Sp1 transcription factor family can act as both negative and positive regulators of gene expression. Here we show that Sp1 can be a target for histone deacetylase 1 (HDAC1)-mediated transcriptional repression. The histone deacetylase inhibitor trichostatin A activates the chromosomally integrated murine thymidine kinase promoter in an Sp1-dependent manner. Coimmunoprecipitation experiments with Swiss 3T3 fibroblasts and 293 cells demonstrate that Sp1 and HDAC1 can be part of the same complex. The interaction between Sp1 and HDAC1 is direct and requires the carboxy-terminal domain of Sp1. Previously we have shown that the C terminus of Sp1 is necessary for the interaction with the transcription factor E2F1 (J. Karlseder, H. Rotheneder, and E. Wintersberger, Mol. Cell. Biol. 16:1659-1667, 1996). Coexpression of E2F1 interferes with HDAC1 binding to Sp1 and abolishes Sp1-mediated transcriptional repression. Our results indicate that one component of Sp1-dependent gene regulation involves competition between the transcriptional repressor HDAC1 and the transactivating factor E2F1.
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Affiliation(s)
- A Doetzlhofer
- Institute of Molecular Biology, Vienna Biocenter, University of Vienna, Vienna, Austria
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22
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Sutterluety H, Bartl S, Doetzlhofer A, Khier H, Wintersberger E, Seiser C. Growth-regulated antisense transcription of the mouse thymidine kinase gene. Nucleic Acids Res 1998; 26:4989-95. [PMID: 9776764 PMCID: PMC147947 DOI: 10.1093/nar/26.21.4989] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The expression of the salvage pathway enzyme thymidine kinase (TK) is very low in resting mammalian cells, but increases dramatically when growth-stimulated cells enter S phase. The 30-fold rise in TK mRNA levels in response to growth factors is due to a well-characterized transcriptional activation and less defined post-transcriptional mechanisms. A minigene containing the murine TK promoter and the TK cDNA showed a 3-fold increase in TK mRNA levels after growth induction in stably transfected mouse TK-deficient L fibroblasts. Introduction of the first three TK introns resulted in a 10-fold regulation of TK expression which was predominantly due to repressed TK mRNA levels in serum-deprived cells. Removal of intron 3 from this construct or replacement of the TK promoter by a constitutive SV40 promoter led to a reduced, but still significant increase in TK mRNA levels during the onset of proliferation. These results indicate that both the TK promoter and specific TK introns contribute independently to the growth-dependent regulation of TK mRNA expression. To examine the regulatory mechanisms in more detail we analyzed TK transcription rates and steady-state levels of nuclear transcripts from an SV40 promoter-driven minigene that contains introns 2 and 3 of the TK gene. Using a set of single-stranded probes we detected TK-specific antisense transcription that was up-regulated in resting cells. Similarly, antisense transcription of the endogenous TK gene in Swiss 3T3 cells rose during serum deprivation while sense transcription was regulated in the opposite way. Luciferase reporter assays revealed the presence of a putative antisense promoter in intron 3 of the murine TK gene. These results suggest a negative role for intron-dependent antisense transcription in the regulation of TK mRNA expression in mouse fibroblasts.
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Affiliation(s)
- H Sutterluety
- Institute of Molecular Biology, University of Vienna, Vienna Biocenter, Dr Bohr-Gasse 9, A-1030 Vienna, Austria
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