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Pyott SJ, Pavlinkova G, Yamoah EN, Fritzsch B. Harmony in the Molecular Orchestra of Hearing: Developmental Mechanisms from the Ear to the Brain. Annu Rev Neurosci 2024; 47:1-20. [PMID: 38360566 DOI: 10.1146/annurev-neuro-081423-093942] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2024]
Abstract
Auditory processing in mammals begins in the peripheral inner ear and extends to the auditory cortex. Sound is transduced from mechanical stimuli into electrochemical signals of hair cells, which relay auditory information via the primary auditory neurons to cochlear nuclei. Information is subsequently processed in the superior olivary complex, lateral lemniscus, and inferior colliculus and projects to the auditory cortex via the medial geniculate body in the thalamus. Recent advances have provided valuable insights into the development and functioning of auditory structures, complementing our understanding of the physiological mechanisms underlying auditory processing. This comprehensive review explores the genetic mechanisms required for auditory system development from the peripheral cochlea to the auditory cortex. We highlight transcription factors and other genes with key recurring and interacting roles in guiding auditory system development and organization. Understanding these gene regulatory networks holds promise for developing novel therapeutic strategies for hearing disorders, benefiting millions globally.
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Affiliation(s)
- Sonja J Pyott
- Department of Otorhinolaryngology and Head and Neck Surgery, University Medical Center Groningen, Graduate School of Medical Sciences, and Research School of Behavioral and Cognitive Neurosciences, University of Groningen, Groningen, The Netherlands
| | - Gabriela Pavlinkova
- Laboratory of Molecular Pathogenetics, Institute of Biotechnology, Czech Academy of Sciences, Vestec, Czechia
| | - Ebenezer N Yamoah
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Nevada, USA
| | - Bernd Fritzsch
- Department of Neurological Sciences, University of Nebraska Medical Center, Omaha, Nebraska, USA;
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2
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Goodrich EJ, Deans MR. Emx2 lineage tracing reveals antecedent patterns of planar polarity in the mouse inner ear. Development 2024; 151:dev202425. [PMID: 38682291 PMCID: PMC11165714 DOI: 10.1242/dev.202425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 04/18/2024] [Indexed: 05/01/2024]
Abstract
The planar polarized organization of hair cells in the vestibular maculae is unique because these sensory organs contain two groups of cells with oppositely oriented stereociliary bundles that meet at a line of polarity reversal (LPR). EMX2 is a transcription factor expressed by one hair cell group that reverses the orientation of their bundles, thereby forming the LPR. We generated Emx2-CreERt2 transgenic mice for genetic lineage tracing and demonstrate Emx2 expression before hair cell specification when the nascent utricle and saccule constitute a continuous prosensory domain. Precursors labeled by Emx2-CreERt2 at this stage give rise to hair cells located along one side of the LPR in the mature utricle or saccule, indicating that this boundary is first established in the prosensory domain. Consistent with this, Emx2-CreERt2 lineage tracing in Dreher mutants, where the utricle and saccule fail to segregate, labels a continuous field of cells along one side of a fused utriculo-saccular-cochlear organ. These observations reveal that LPR positioning is pre-determined in the developing prosensory domain, and that EMX2 expression defines lineages of hair cells with oppositely oriented stereociliary bundles.
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Affiliation(s)
- Ellison J. Goodrich
- Department of Neurobiology, Spencer Fox Eccles School of Medicine at the University of Utah, Salt Lake City, UT 84112, USA
| | - Michael R. Deans
- Department of Neurobiology, Spencer Fox Eccles School of Medicine at the University of Utah, Salt Lake City, UT 84112, USA
- Department of Otolaryngology – Head and Neck Surgery, Spencer Fox Eccles School of Medicine at the University of Utah, Salt Lake City, UT 84132, USA
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3
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Young CA, Burt E, Munnamalai V. Sensory progenitors influence patterning of the mammalian auditory sensory epithelium. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.13.566920. [PMID: 38014307 PMCID: PMC10680690 DOI: 10.1101/2023.11.13.566920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
During embryonic development Wnt signaling has been shown to influence proliferation and sensory formation in the cochlea. How the dual nature of Wnt signaling is coordinated is unknown. In this study, we define a novel role for a Wnt regulated gene, Mybl2, which was already known to be important for proliferation, in influencing patterning and determining the size of the sensory epithelium in the murine cochlea. Using a quantitative spatial analysis approach and analyzing Mybl2 loss-of-function cochleas, we show that Mybl2 simultaneously specifies the progenitor niche and the size of the sensory domain, and influences the positioning of the medial sensory domain boundary via Jag1 regulation during the mid-gestational stages. Mybl2 conditional knockout resulted in a decrease of proliferation within the progenitor niche. During the late embryonic stages, conditional knockout of Mybl2 produced a wider sensory epithelium across the radial axis with an increase in ectopic inner hair cell formation. These data suggest that Mybl2 -positive progenitors play a role in boundary formation and patterning the sensory epithelium. Summary Statement Mybl2 is a Wnt-regulated gene encoding a transcription factor that is expressed in the cochlear progenitor niche and influences the boundary formation between the niche and the sensory domain during mid-cochlear developmental stages, thereby impacting the size of the sensory epithelium.
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Cetera M, Sharan R, Hayward-Lara G, Phillips B, Biswas A, Halley M, Beall E, vonHoldt B, Devenport D. Region-specific reversal of epidermal planar polarity in the rosette fancy mouse. Development 2023; 150:dev202078. [PMID: 37622728 PMCID: PMC10499026 DOI: 10.1242/dev.202078] [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: 06/13/2023] [Accepted: 08/21/2023] [Indexed: 08/26/2023]
Abstract
The planar cell polarity (PCP) pathway collectively orients cells with respect to a body axis. Hair follicles of the murine epidermis provide a striking readout of PCP activity in their uniform alignment across the skin. Here, we characterize, from the molecular to tissue-scale, PCP establishment in the rosette fancy mouse, a natural variant with posterior-specific whorls in its fur, to understand how epidermal polarity is coordinated across the tissue. We find that rosette hair follicles emerge with reversed orientations specifically in the posterior region, creating a mirror image of epidermal polarity. The rosette trait is associated with a missense mutation in the core PCP gene Fzd6, which alters a consensus site for N-linked glycosylation, inhibiting its membrane localization. Unexpectedly, the Fzd6 trafficking defect does not block asymmetric localization of the other PCP proteins. Rather, the normally uniform axis of PCP asymmetry rotates where the PCP-directed cell movements that orient follicles are reversed, suggesting the PCP axis rotates 180°. Collectively, our multiscale analysis of epidermal polarity reveals PCP patterning can be regionally decoupled to produce posterior whorls in the rosette fancy mouse.
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Affiliation(s)
- Maureen Cetera
- Department of Genetics, Cell Biology and Development, University of Minnesota Twin Cities, Minneapolis, MN 55455, USA
| | - Rishabh Sharan
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08540, USA
| | | | - Brooke Phillips
- Department of Molecular Biology, Princeton University, Princeton, NJ 08540, USA
| | - Abhishek Biswas
- Department of Molecular Biology, Princeton University, Princeton, NJ 08540, USA
- Research Computing, Office of Information Technology, Princeton University, Princeton, NJ 08540, USA
| | - Madalene Halley
- Department of Genetics, Cell Biology and Development, University of Minnesota Twin Cities, Minneapolis, MN 55455, USA
| | - Evalyn Beall
- Department of Genetics, Cell Biology and Development, University of Minnesota Twin Cities, Minneapolis, MN 55455, USA
| | - Bridgett vonHoldt
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ 08540, USA
| | - Danelle Devenport
- Department of Molecular Biology, Princeton University, Princeton, NJ 08540, USA
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5
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Cetera M, Sharan R, Hayward-Lara G, Phillips B, Biswas A, Halley M, Beall E, vonHoldt B, Devenport D. Region-specific reversal of epidermal planar polarity in the fancy rosette mouse. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.27.550849. [PMID: 37546950 PMCID: PMC10402159 DOI: 10.1101/2023.07.27.550849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
The planar cell polarity (PCP) pathway collectively orients thousands of cells with respect to a body axis to direct cellular behaviors that are essential for embryonic morphogenesis. Hair follicles of the murine epidermis provide a striking readout of PCP activity in their uniform alignment along the entire skin surface. Here, we characterize, from the molecular to tissue-scale, PCP establishment in the rosette fancy mouse, a natural variant with posterior-specific whorls in its fur, to understand how epidermal polarity is coordinated across the tissue. We find that embryonic hair follicles of rosette mutants emerge with reversed orientations specifically in the posterior region, creating a mirror image of epidermal polarity. The rosette trait is associated with a missense mutation in the core PCP gene Fzd6 , which alters a consensus site for N-linked glycosylation and inhibits its membrane localization. Unexpectedly, this defect in Fzd6 trafficking, observed across the entire dorsal epidermis, does not interfere with the ability of other core PCP proteins to localize asymmetrically. Rather, the normally uniform axis of PCP asymmetry is disrupted and rotated in the posterior region such that polarity is reflected on either side of a transition zone. The result is a reversal of polarized cell movements that orient nascent follicles, specifically in the posterior of the embryo. Collectively, our multiscale analysis of epidermal polarity reveals PCP patterning can be regionally decoupled to produce the unique posterior whorls of the fancy rosette mouse. Summary Region-specific rotation of the Planar Cell Polarity axis reverses posterior hair follicles in the fancy rosette mouse.
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Jia S, Ratzan EM, Goodrich EJ, Abrar R, Heiland L, Tarchini B, Deans MR. The dark kinase STK32A regulates hair cell planar polarity opposite of EMX2 in the developing mouse inner ear. eLife 2023; 12:e84910. [PMID: 37144879 PMCID: PMC10202454 DOI: 10.7554/elife.84910] [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: 11/14/2022] [Accepted: 05/03/2023] [Indexed: 05/06/2023] Open
Abstract
The vestibular maculae of the inner ear contain sensory receptor hair cells that detect linear acceleration and contribute to equilibrioception to coordinate posture and ambulatory movements. These hair cells are divided between two groups, separated by a line of polarity reversal (LPR), with oppositely oriented planar-polarized stereociliary bundles that detect motion in opposite directions. The transcription factor EMX2 is known to establish this planar polarized organization in mouse by regulating the distribution of the transmembrane receptor GPR156 at hair cell boundaries in one group of cells. However, the genes regulated by EMX2 in this context were previously not known. Using mouse as a model, we have identified the serine threonine kinase STK32A as a downstream effector negatively regulated by EMX2. Stk32a is expressed in hair cells on one side of the LPR in a pattern complementary to Emx2 expression in hair cells on the opposite side. Stk32a is necessary to align the intrinsic polarity of the bundle with the core planar cell polarity (PCP) proteins in EMX2-negative regions, and is sufficient to reorient bundles when ectopically expressed in neighboring EMX2-positive regions. We demonstrate that STK32A reinforces LPR formation by regulating the apical localization of GPR156. These observations support a model in which bundle orientation is determined through separate mechanisms in hair cells on opposite sides of the maculae, with EMX2-mediated repression of Stk32a determining the final position of the LPR.
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Affiliation(s)
- Shihai Jia
- Department of Neurobiology, Spencer Fox Eccles School of Medicine at the University of UtahSalt Lake CityUnited States
| | - Evan M Ratzan
- Interdepartmental Program in Neuroscience, Spencer Fox Eccles School of Medicine at the University of UtahSalt Lake CityUnited States
- Departments of Otolaryngology and Neurology, Boston Children’s Hospital and Harvard Medical SchoolBostonUnited States
| | - Ellison J Goodrich
- Department of Neurobiology, Spencer Fox Eccles School of Medicine at the University of UtahSalt Lake CityUnited States
| | - Raisa Abrar
- Department of Neurobiology, Spencer Fox Eccles School of Medicine at the University of UtahSalt Lake CityUnited States
| | - Luke Heiland
- Department of Otolaryngology, Spencer Fox Eccles School of Medicine at the University of UtahSalt Lake CityUnited States
| | - Basile Tarchini
- The Jackson LaboratoryBar HarborUnited States
- Tufts University School of MedicineBostonUnited States
| | - Michael R Deans
- Department of Neurobiology, Spencer Fox Eccles School of Medicine at the University of UtahSalt Lake CityUnited States
- Department of Otolaryngology, Spencer Fox Eccles School of Medicine at the University of UtahSalt Lake CityUnited States
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7
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Chen X, Wan H, Bai Y, Zhang Y, Hua Q. Advances in Understanding the Notch Signaling Pathway in the Cochlea. Curr Pharm Des 2023; 29:3266-3273. [PMID: 37990430 DOI: 10.2174/0113816128273532231103110910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Accepted: 10/17/2023] [Indexed: 11/23/2023]
Abstract
The cochlear structure is highly complex and specific, and its development is regulated by multiple signaling pathways. Abnormalities in cochlear development can lead to different degrees of loss of function. Hair cells (HCs), which are difficult to regenerate in the mature mammalian cochlea, are susceptible to damage from noise and ototoxic drugs, and damage to HCs can cause hearing loss to varying degrees. Notch, a classical developmental signaling molecule, has been shown to be closely associated with embryonic cochlear development and plays an important role in HC regeneration in mammals, suggesting that the Notch signaling pathway may be a potential therapeutic target for cochlear development and hearing impairment due to HC damage. In recent years, the important role of the Notch signaling pathway in the cochlea has received increasing attention. In this paper, we review the role of Notch signaling in cochlear development and HC regeneration, with the aim of providing new research ideas for the prevention and treatment of related diseases.
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Affiliation(s)
- Xiaoying Chen
- Department of Otolaryngology-Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Huanzhi Wan
- Department of Otolaryngology-Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Yutong Bai
- Department of Otolaryngology-Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Yuanyuan Zhang
- Department of Otolaryngology-Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan 430060, China
| | - Qingquan Hua
- Department of Otolaryngology-Head and Neck Surgery, Renmin Hospital of Wuhan University, Wuhan 430060, China
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8
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Glover JC, Fritzsch B. Molecular mechanisms governing development of the hindbrain choroid plexus and auditory projection: A validation of the seminal observations of Wilhelm His. IBRO Neurosci Rep 2022; 13:306-313. [PMID: 36247525 PMCID: PMC9561746 DOI: 10.1016/j.ibneur.2022.09.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 09/29/2022] [Accepted: 09/29/2022] [Indexed: 11/05/2022] Open
Abstract
Studies by His from 1868 to 1904 delineated the critical role of the dorsal roof plate in the development of the hindbrain choroid plexus, and of the rhombic lips in the development of hindbrain auditory centers. Modern molecular studies have confirmed these observations and placed them in a mechanistic context. Expression of the transcription factor Lmx1a/b is crucial to the development of the hindbrain choroid plexus, and also regulates the expression of Atoh1, a transcription factor that is essential for the formation of the cochlear hair cells and auditory nuclei. By contrast, development of the vestibular hair cells, vestibular ganglion and vestibular nuclei does not depend on Lmx1a/b. These findings demonstrate a common dependence on a specific gene for the hindbrain choroid plexus and the primary auditory projection from hair cells to sensory neurons to hindbrain nuclei. Thus, His' conclusions regarding the origins of specific hindbrain structures are borne out by molecular genetic experiments conducted more than a hundred years later.
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Affiliation(s)
- Joel C. Glover
- Department of Molecular Medicine, University of Oslo, Oslo, Norway
- Norwegian Center for Stem Cell Research, Oslo University Hospital, Oslo, Norway
- Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, Norway
- Corresponding author at: Department of Molecular Medicine, University of Oslo, Oslo, Norway.
| | - Bernd Fritzsch
- Department of Biology, University of Iowa, Iowa, IA 52242, USA
- Corresponding author.
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9
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Fritzsch B, Elliott KL, Yamoah EN. Neurosensory development of the four brainstem-projecting sensory systems and their integration in the telencephalon. Front Neural Circuits 2022; 16:913480. [PMID: 36213204 PMCID: PMC9539932 DOI: 10.3389/fncir.2022.913480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 08/23/2022] [Indexed: 11/18/2022] Open
Abstract
Somatosensory, taste, vestibular, and auditory information is first processed in the brainstem. From the brainstem, the respective information is relayed to specific regions within the cortex, where these inputs are further processed and integrated with other sensory systems to provide a comprehensive sensory experience. We provide the organization, genetics, and various neuronal connections of four sensory systems: trigeminal, taste, vestibular, and auditory systems. The development of trigeminal fibers is comparable to many sensory systems, for they project mostly contralaterally from the brainstem or spinal cord to the telencephalon. Taste bud information is primarily projected ipsilaterally through the thalamus to reach the insula. The vestibular fibers develop bilateral connections that eventually reach multiple areas of the cortex to provide a complex map. The auditory fibers project in a tonotopic contour to the auditory cortex. The spatial and tonotopic organization of trigeminal and auditory neuron projections are distinct from the taste and vestibular systems. The individual sensory projections within the cortex provide multi-sensory integration in the telencephalon that depends on context-dependent tertiary connections to integrate other cortical sensory systems across the four modalities.
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Affiliation(s)
- Bernd Fritzsch
- Department of Biology, The University of Iowa, Iowa City, IA, United States
- Department of Otolaryngology, The University of Iowa, Iowa City, IA, United States
- *Correspondence: Bernd Fritzsch,
| | - Karen L. Elliott
- Department of Biology, The University of Iowa, Iowa City, IA, United States
| | - Ebenezer N. Yamoah
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Reno, NV, United States
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10
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Keer S, Cousin H, Jourdeuil K, Neilson KM, Tavares ALP, Alfandari D, Moody SA. Mcrs1 is required for branchial arch and cranial cartilage development. Dev Biol 2022; 489:62-75. [PMID: 35697116 PMCID: PMC10426812 DOI: 10.1016/j.ydbio.2022.06.002] [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: 02/04/2022] [Revised: 06/06/2022] [Accepted: 06/08/2022] [Indexed: 11/22/2022]
Abstract
Mcrs1 is a multifunctional protein that is critical for many cellular processes in a wide range of cell types. Previously, we showed that Mcrs1 binds to the Six1 transcription factor and reduces the ability of the Six1-Eya1 complex to upregulate transcription, and that Mcrs1 loss-of-function leads to the expansion of several neural plate genes, reduction of neural border and pre-placodal ectoderm (PPR) genes, and pleiotropic effects on various neural crest (NC) genes. Because the affected embryonic structures give rise to several of the cranial tissues affected in Branchio-otic/Branchio-oto-renal (BOR) syndrome, herein we tested whether these gene expression changes subsequently alter the development of the proximate precursors of BOR affected structures - the otic vesicles (OV) and branchial arches (BA). We found that Mcrs1 is required for the expression of several OV genes involved in inner ear formation, patterning and otic capsule cartilage formation. Mcrs1 knockdown also reduced the expression domains of many genes expressed in the larval BA, derived from either NC or PPR, except for emx2, which was expanded. Reduced Mcrs1 also diminished the length of the expression domain of tbx1 in BA1 and BA2 and interfered with cranial NC migration from the dorsal neural tube; this subsequently resulted in defects in the morphology of lower jaw cartilages derived from BA1 and BA2, including the infrarostral, Meckel's, and ceratohyal as well as the otic capsule. These results demonstrate that Mcrs1 plays an important role in processes that lead to the formation of craniofacial cartilages and its loss results in phenotypes consistent with reduced Six1 activity associated with BOR.
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Affiliation(s)
- Stephanie Keer
- Department of Anatomy and Cell Biology, The George Washington University School of Medicine and Health Sciences, 2300 I (eye) Street, NW, Washington, DC, 20037, USA
| | - Helene Cousin
- Department of Animal Science, University of Massachusetts Amherst, Integrated Science Building, 661 N. Pleasant Street, Amherst, MA, 01003, USA
| | - Karyn Jourdeuil
- Department of Anatomy and Cell Biology, The George Washington University School of Medicine and Health Sciences, 2300 I (eye) Street, NW, Washington, DC, 20037, USA
| | - Karen M Neilson
- Department of Anatomy and Cell Biology, The George Washington University School of Medicine and Health Sciences, 2300 I (eye) Street, NW, Washington, DC, 20037, USA
| | - Andre L P Tavares
- Department of Anatomy and Cell Biology, The George Washington University School of Medicine and Health Sciences, 2300 I (eye) Street, NW, Washington, DC, 20037, USA
| | - Dominique Alfandari
- Department of Animal Science, University of Massachusetts Amherst, Integrated Science Building, 661 N. Pleasant Street, Amherst, MA, 01003, USA
| | - Sally A Moody
- Department of Anatomy and Cell Biology, The George Washington University School of Medicine and Health Sciences, 2300 I (eye) Street, NW, Washington, DC, 20037, USA.
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11
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Mary L, Leclerc D, Gilot D, Belaud-Rotureau MA, Jaillard S. The TALE never ends: A comprehensive overview of the role of PBX1, a TALE transcription factor, in human developmental defects. Hum Mutat 2022; 43:1125-1148. [PMID: 35451537 DOI: 10.1002/humu.24388] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 03/25/2022] [Accepted: 04/20/2022] [Indexed: 11/07/2022]
Abstract
PBX1 is a highly conserved atypical homeodomain transcription factor (TF) belonging to the TALE (three amino acid loop extension) family. Dimerized with other TALE proteins, it can interact with numerous partners and reach dozens of regulating sequences, suggesting its role as a pioneer factor. PBX1 is expressed throughout the embryonic stages (as early as the blastula stage) in vertebrates. In human, PBX1 germline variations are linked to syndromic renal anomalies (CAKUTHED). In this review, we summarized available data on PBX1 functions, PBX1-deficient animal models, and PBX1 germline variations in humans. Two types of genetic alterations were identified in PBX1 gene. PBX1 missense variations generate a severe phenotype including lung hypoplasia, cardiac malformations, and sexual development defects (DSDs). Conversely, truncating variants generate milder phenotypes (mainly cryptorchidism and deafness). We suggest that defects in PBX1 interactions with various partners, including proteins from the HOX (HOXA7, HOXA10, etc.), WNT (WNT9B, WNT3), and Polycomb (BMI1, EED) families are responsible for abnormal proliferation and differentiation of the embryonic mesenchyme. These alterations could explain most of the defects observed in humans. However, some phenotype variability (especially DSDs) remains poorly understood. Further studies are needed to explore the TALE family in greater depth.
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Affiliation(s)
- Laura Mary
- Service de Cytogénétique et Biologie Cellulaire, CHU Rennes, Rennes, France
- INSERM, EHESP, IRSET (Institut de recherche en santé, environnement et travail)- UMR_S 1085, Université Rennes 1, Rennes, France
| | - Delphine Leclerc
- Inserm U1242, Centre de lutte contre le cancer Eugène Marquis, Université de Rennes, Rennes, France
| | - David Gilot
- Service de Cytogénétique et Biologie Cellulaire, CHU Rennes, Rennes, France
- Inserm U1242, Centre de lutte contre le cancer Eugène Marquis, Université de Rennes, Rennes, France
| | - Marc-Antoine Belaud-Rotureau
- Service de Cytogénétique et Biologie Cellulaire, CHU Rennes, Rennes, France
- INSERM, EHESP, IRSET (Institut de recherche en santé, environnement et travail)- UMR_S 1085, Université Rennes 1, Rennes, France
| | - Sylvie Jaillard
- Service de Cytogénétique et Biologie Cellulaire, CHU Rennes, Rennes, France
- INSERM, EHESP, IRSET (Institut de recherche en santé, environnement et travail)- UMR_S 1085, Université Rennes 1, Rennes, France
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12
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Li H, Liao S, Luo G, Li H, Wang S, Li Z, Luo X. An Association between EMX2 Variations and Mayer-Rokitansky-Küster-Hauser Syndrome: A Case-Control Study of Chinese Women. JOURNAL OF HEALTHCARE ENGINEERING 2022; 2022:9975369. [PMID: 35463657 PMCID: PMC9020933 DOI: 10.1155/2022/9975369] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 03/16/2022] [Accepted: 03/18/2022] [Indexed: 01/08/2023]
Abstract
Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome is characterized by congenital malformations of Müllerian structures, including the uterus and upper two-thirds of the vagina in women. Until now, the etiology of this disease has remained unknown. We hypothesized that EMX2 (the human homologue of Drosophila empty spiracles gene (2) might be a candidate gene for MRKH syndrome because it plays an important role in the development of the urogenital system. Through sequence analysis of EMX2 in forty patients with MRKH syndrome and one hundred and forty healthy women controls, we identified eleven variations in total. Four novel variations were only found in MRKH patients, and seven single nucleotide polymorphisms were identified in both patients and controls. In silico analyses suggested that the novel variations in the 5'UTR (untranslated region) and 3'UTR might affect transcriptional activity of the EMX2 promoter or posttranscriptional processing. In conclusion, our study suggests an association between noncoding variations in the EMX2 gene and MRKH syndrome in a Chinese Han population.
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Affiliation(s)
- Haiping Li
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of Jinan University, Guangzhou, Guangdong 511442, China
- Department of Gynecology, Guangdong Women and Children Hospital, Guangzhou, Guangdong 511442, China
| | - Shi Liao
- Department of Gynecology, The Third Affiliated Hospital of Shenzhen University, Shenzhen, Guangdong 518005, China
| | - Guangnan Luo
- Department of Gynecology, The Third Affiliated Hospital of Shenzhen University, Shenzhen, Guangdong 518005, China
| | - Haixia Li
- School of Basic Medical Sciences, Hubei University of Medicine, Shiyan, Hubei 442000, China
| | - Shuai Wang
- Department of Obstetrics and Gynecology, The Sixth Affiliated Hospital, South China University of Technology, Foshan, Guangdong 528237, China
| | - Zhimin Li
- Department of Gynecology, Guangdong Women and Children Hospital, Guangzhou, Guangdong 511442, China
| | - Xiping Luo
- Department of Obstetrics and Gynecology, The First Affiliated Hospital of Jinan University, Guangzhou, Guangdong 511442, China
- Department of Gynecology, Guangdong Women and Children Hospital, Guangzhou, Guangdong 511442, China
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13
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Jiang Y, Chen S. Functional New Transcription Factors (TFs) Associated with Cervical Cancer. JOURNAL OF HEALTHCARE ENGINEERING 2022; 2022:8381559. [PMID: 35126951 PMCID: PMC8808228 DOI: 10.1155/2022/8381559] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Revised: 12/10/2021] [Accepted: 12/20/2021] [Indexed: 11/17/2022]
Abstract
The goal of this research was to find noval transcription factors (TFs) that are involved in cervical carcinogenesis. The Gene Expression Omnibus (GEO) database was utilized to analyze ten cervical cancer datasets using the Robust Rank Aggregation (RRA) technique. Survival and differential expression were validated using GEPIA (Gene Expression Profiling Interactive Analysis). The transcriptional regulatory network and putative targets were built using Cytoscape. A real-time PCR (quantitative real-time polymerase chain reaction) experiment was used to confirm the mRNA expression. Using public cervical cancer single-cell RNA-sequencing (scRNA-seq), bulk TCGA-CESC RNA-seq, and microarray datasets, coexpression correlations between putative targets and TFs were confirmed. After combining the results of 10 datasets, 8 TFs, including EMX2 (Empty Spiracles Homeobox 2), were chosen among 385 robust DEGs. In the normal female reproductive tract, EMX2 is extensively expressed, but it is reduced in cervical cancer. Overexpression EMX2 suppresses the proliferation of HeLa cells. 12 potential targets of EMX2 were selected. Our research has revealed evidence that EMX2 acted as a tumor suppressor in cervical cancer and PDZRN3 might be possible target of EMX2 in cervical cancer. It might be a therapeutic target in the future.
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Affiliation(s)
- Yicheng Jiang
- Department of Oncology, People's Hospital of Chongqing Hechuan, Chongqing, China
| | - Shi Chen
- Department of Oncology, Chengdu Jinniu District People's Hospital, Chengdu, Sichuan, China
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14
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Xu SS, Gao L, Shen M, Lyu F. Whole-Genome Selective Scans Detect Genes Associated With Important Phenotypic Traits in Sheep (Ovis aries ). Front Genet 2021; 12:738879. [PMID: 34868210 PMCID: PMC8637624 DOI: 10.3389/fgene.2021.738879] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 10/28/2021] [Indexed: 11/13/2022] Open
Abstract
Sheep (Ovis aries) is one of the important livestock with diverse phenotypic traits. However, little is known about the molecular mechanism of diverse phenotypic traits in domestic sheep. Using the genome-wide high-density SNP data (600K) in 253 samples from 13 populations, we conducted the tests of selective sweeps (i.e., pairwise FST and XP-CLR) associated with several important phenotypic traits (e.g., tail types, horn morphology, prolificacy, coat pigmentation, ear size, milk production, meat production, body size and wool fineness). We identified strong selective signatures in previously reported (e.g., T, RXFP2, BMPR1B, TYRP1, MSRB3, TF, CEBPA, GPR21 and HOXC8) and novel genes associated with the traits, such as CERS6, BTG1, RYR3, SLC6A4, NNAT and OGT for fat deposition in the tails, FOXO4 for fertility, PTCH1 and EMX2 for ear size, and RMI1 and SCD5 for body size. Further gene annotation analysis showed that these genes were identified to be the most probable genes accounting for the diverse phenotypic traits. Our results provide novel insights into the genetic mechanisms underlying the traits and also new genetic markers for genetic improvement in sheep and other livestock.
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Affiliation(s)
- Song-Song Xu
- College of Animal Science and Technology, China Agricultural University, Beijing, China.,Guangdong Laboratory of Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Shenzhen Branch, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
| | - Lei Gao
- State Key Laboratory of Sheep Genetic Improvement and Healthy Breeding, Xinjiang Academy of Agricultural and Reclamation Sciences, Shihezi, China
| | - Min Shen
- State Key Laboratory of Sheep Genetic Improvement and Healthy Breeding, Xinjiang Academy of Agricultural and Reclamation Sciences, Shihezi, China
| | - Fenghua Lyu
- College of Animal Science and Technology, China Agricultural University, Beijing, China
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15
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Chen BJ, Qian XQ, Yang XY, Jiang T, Wang YM, Lyu JH, Chi FL, Chen P, Ren DD. Rab11a Regulates the Development of Cilia and Establishment of Planar Cell Polarity in Mammalian Vestibular Hair Cells. Front Mol Neurosci 2021; 14:762916. [PMID: 34867187 PMCID: PMC8640494 DOI: 10.3389/fnmol.2021.762916] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 10/25/2021] [Indexed: 11/13/2022] Open
Abstract
Vestibular organs have unique planar cell polarity (Figure 1A), and their normal development and function are dependent on the regular polarity of cilia (Figure 1B) requires. Rab11a is a small G protein that participates in the transportation of intracellular and extracellular materials required for polarity formation; however, our understanding of the mechanisms of the actions of Rab11a in vestibular organs is limited. Here, we showed that the general shape of the utricle was abnormal in Rab11a CKO/CKO mice. These mice also showed abnormal morphology of the stereocilia bundles, which were reduced in both length and number, as well as disturbed tissue-level polarity. Rab11a affected the distribution of polarity proteins in the vestibular organs, indicating that the normal development of cilia requires Rab11a and intraflagellar transportation. Furthermore, small G protein migration works together with intraflagellar transportation in the normal development of cilia. FIGURE 1Morphological changes of stereocilia in the extrastriolar hair cells from Rab11a single or Rab11a/IFT88 double-mutant utricles. (A) Medial view of a mouse left inner ear with its five vestibular sensory organs (gray). Enlarged are the utricle showing their subdivisions, LPR (yellow line), and striola (blue). LES, lateral extrastriola; MES, medial extrastriola; LPR, line of polarity reversal. (B) Schematic view of vestibular hair cell. Kinocilium is marked with ace-tubulin. Basal body is marked with γ-tubulin. (C,C1,D,D1) Normal appearance of the stereocilia of extrastriolar hair cells of wild-type controls. (E,E1,F,F1) Altered morphology in Rab11a CKO/CKO animals. (G,G1,H,H1) The changes in the stereocilia morphology were more severe in Rab11a CKO/CKO /IFT 88 CKO/+ mice. (I-L) Higher magnification of confocal images of hair cells. (M-P) Scanning electron microscopy images of hair cells from wild-type controls and Rab11a mutants. (I,M) Morphology of normal. hair cells of wild-type controls. (J,N) The number of stereocilia on a single hair cell was deceased in the Rab11a mutant. (K,O) Stereocilia were shorter in mutants compared to the wild-type controls. (L,P) The staircase-like hair bundle architecture of hair cells was lost in Rab11a mutant mice. (Q) The percentage of hair cells with abnormal development of static cilia bundles in the extrastriola region was counted as a percentage of the total (n = 5). The percentage of abnormal hair cells was higher in Rab11a CKO/CKO , IFT88 CKO/+ mice compared to Rab11a CKO/CKO . The abnormal ratios of single and double knockout hair cells were 42.1 ± 5.7 and 71.5 ± 10.4, respectively. In (A-J), for all primary panels, hair cell stereociliary bundles were marked with phalloidin (green), the actin-rich cuticular plate of hair cells was labeled with β-spectrin (red), while the basal body of the hair cell was labeled with γ-tubulin (blue). Scale bars: 10 μm (C-H1), 5 μm (J-N). *P < 0.05.
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Affiliation(s)
- Bin-Jun Chen
- Department of Otorhinolaryngology, ENT Institute, Eye and ENT Hospital, Fudan University, Shanghai, China.,NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China.,Shanghai Auditory Medical Center, Shanghai, China
| | - Xiao-Qing Qian
- Department of Otorhinolaryngology, ENT Institute, Eye and ENT Hospital, Fudan University, Shanghai, China.,NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China.,Shanghai Auditory Medical Center, Shanghai, China
| | - Xiao-Yu Yang
- Department of Otorhinolaryngology, ENT Institute, Eye and ENT Hospital, Fudan University, Shanghai, China.,NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China.,Shanghai Auditory Medical Center, Shanghai, China
| | - Tao Jiang
- Department of Otorhinolaryngology, ENT Institute, Eye and ENT Hospital, Fudan University, Shanghai, China.,NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China.,Shanghai Auditory Medical Center, Shanghai, China
| | - Yan-Mei Wang
- Department of Otorhinolaryngology, ENT Institute, Eye and ENT Hospital, Fudan University, Shanghai, China.,NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China.,Shanghai Auditory Medical Center, Shanghai, China
| | - Ji-Han Lyu
- Department of Otorhinolaryngology, ENT Institute, Eye and ENT Hospital, Fudan University, Shanghai, China.,NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China.,Shanghai Auditory Medical Center, Shanghai, China
| | - Fang-Lu Chi
- Department of Otorhinolaryngology, ENT Institute, Eye and ENT Hospital, Fudan University, Shanghai, China.,NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China.,Shanghai Auditory Medical Center, Shanghai, China
| | - Ping Chen
- Department of Cell Biology, Emory University, Atlanta, GA, United States.,Department of Otolaryngology, Emory University, Atlanta, GA, United States
| | - Dong-Dong Ren
- Department of Otorhinolaryngology, ENT Institute, Eye and ENT Hospital, Fudan University, Shanghai, China.,NHC Key Laboratory of Hearing Medicine, Fudan University, Shanghai, China.,Shanghai Auditory Medical Center, Shanghai, China
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16
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Deans MR. Conserved and Divergent Principles of Planar Polarity Revealed by Hair Cell Development and Function. Front Neurosci 2021; 15:742391. [PMID: 34733133 PMCID: PMC8558554 DOI: 10.3389/fnins.2021.742391] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 09/28/2021] [Indexed: 11/13/2022] Open
Abstract
Planar polarity describes the organization and orientation of polarized cells or cellular structures within the plane of an epithelium. The sensory receptor hair cells of the vertebrate inner ear have been recognized as a preeminent vertebrate model system for studying planar polarity and its development. This is principally because planar polarity in the inner ear is structurally and molecularly apparent and therefore easy to visualize. Inner ear planar polarity is also functionally significant because hair cells are mechanosensors stimulated by sound or motion and planar polarity underlies the mechanosensory mechanism, thereby facilitating the auditory and vestibular functions of the ear. Structurally, hair cell planar polarity is evident in the organization of a polarized bundle of actin-based protrusions from the apical surface called stereocilia that is necessary for mechanosensation and when stereociliary bundle is disrupted auditory and vestibular behavioral deficits emerge. Hair cells are distributed between six sensory epithelia within the inner ear that have evolved unique patterns of planar polarity that facilitate auditory or vestibular function. Thus, specialized adaptations of planar polarity have occurred that distinguish auditory and vestibular hair cells and will be described throughout this review. There are also three levels of planar polarity organization that can be visualized within the vertebrate inner ear. These are the intrinsic polarity of individual hair cells, the planar cell polarity or coordinated orientation of cells within the epithelia, and planar bipolarity; an organization unique to a subset of vestibular hair cells in which the stereociliary bundles are oriented in opposite directions but remain aligned along a common polarity axis. The inner ear with its complement of auditory and vestibular sensory epithelia allows these levels, and the inter-relationships between them, to be studied using a single model organism. The purpose of this review is to introduce the functional significance of planar polarity in the auditory and vestibular systems and our contemporary understanding of the developmental mechanisms associated with organizing planar polarity at these three cellular levels.
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Affiliation(s)
- Michael R Deans
- Department of Surgery, Division of Otolaryngology, University of Utah School of Medicine, Salt Lake City, UT, United States.,Department of Neurobiology, University of Utah School of Medicine, Salt Lake City, UT, United States
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17
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Tarchini B. A Reversal in Hair Cell Orientation Organizes Both the Auditory and Vestibular Organs. Front Neurosci 2021; 15:695914. [PMID: 34646115 PMCID: PMC8502876 DOI: 10.3389/fnins.2021.695914] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 09/03/2021] [Indexed: 01/17/2023] Open
Abstract
Sensory hair cells detect mechanical stimuli with their hair bundle, an asymmetrical brush of actin-based membrane protrusions, or stereocilia. At the single cell level, stereocilia are organized in rows of graded heights that confer the hair bundle with intrinsic directional sensitivity. At the organ level, each hair cell is precisely oriented so that its intrinsic directional sensitivity matches the direction of mechanical stimuli reaching the sensory epithelium. Coordinated orientation among neighboring hair cells usually ensures the delivery of a coherent local group response. Accordingly, hair cell orientation is locally uniform in the auditory and vestibular cristae epithelia in birds and mammals. However, an exception to this rule is found in the vestibular macular organs, and in fish lateral line neuromasts, where two hair cell populations show opposing orientations. This mirror-image hair cell organization confers bidirectional sensitivity at the organ level. Here I review our current understanding of the molecular machinery that produces mirror-image organization through a regional reversal of hair cell orientation. Interestingly, recent evidence suggests that auditory hair cells adopt their normal uniform orientation through a global reversal mechanism similar to the one at work regionally in macular and neuromast organs. Macular and auditory organs thus appear to be patterned more similarly than previously appreciated during inner ear development.
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Affiliation(s)
- Basile Tarchini
- The Jackson Laboratory, Bar Harbor, ME, United States.,Department of Medicine, Tufts University, Boston, MA, United States.,Graduate School of Biomedical Science and Engineering (GSBSE), University of Maine, Orono, ME, United States
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18
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An Integrated Perspective of Evolution and Development: From Genes to Function to Ear, Lateral Line and Electroreception. DIVERSITY 2021; 13. [PMID: 35505776 PMCID: PMC9060560 DOI: 10.3390/d13080364] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Four sensory systems (vestibular, lateral line, electroreception, auditory) are unique and project exclusively to the brainstem of vertebrates. All sensory neurons depend on a common set of genes (Eya1, Sox2, Neurog1, Neurod1) that project to a dorsal nucleus and an intermediate nucleus, which differentiate into the vestibular ear, lateral line and electroreception in vertebrates. In tetrapods, a loss of two sensory systems (lateral line, electroreception) leads to the development of a unique ear and auditory system in amniotes. Lmx1a/b, Gdf7, Wnt1/3a, BMP4/7 and Atoh1 define the lateral line, electroreception and auditory nuclei. In contrast, vestibular nuclei depend on Neurog1/2, Ascl1, Ptf1a and Olig3, among others, to develop an independent origin of the vestibular nuclei. A common origin of hair cells depends on Eya1, Sox2 and Atoh1, which generate the mechanosensory cells. Several proteins define the polarity of hair cells in the ear and lateral line. A unique connection of stereocilia requires CDH23 and PCDH15 for connections and TMC1/2 proteins to perceive mechanosensory input. Electroreception has no polarity, and a different system is used to drive electroreceptors. All hair cells function by excitation via ribbons to activate neurons that innervate the distinct target areas. An integrated perspective is presented to understand the gain and loss of different sensory systems.
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19
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Kindt KS, Akturk A, Jarysta A, Day M, Beirl A, Flonard M, Tarchini B. EMX2-GPR156-Gαi reverses hair cell orientation in mechanosensory epithelia. Nat Commun 2021; 12:2861. [PMID: 34001891 PMCID: PMC8129141 DOI: 10.1038/s41467-021-22997-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 04/10/2021] [Indexed: 12/21/2022] Open
Abstract
Hair cells detect sound, head position or water movements when their mechanosensory hair bundle is deflected. Each hair bundle has an asymmetric architecture that restricts stimulus detection to a single axis. Coordinated hair cell orientations within sensory epithelia further tune stimulus detection at the organ level. Here, we identify GPR156, an orphan GPCR of unknown function, as a critical regulator of hair cell orientation. We demonstrate that the transcription factor EMX2 polarizes GPR156 distribution, enabling it to signal through Gαi and trigger a 180° reversal in hair cell orientation. GPR156-Gαi mediated reversal is essential to establish hair cells with mirror-image orientations in mouse otolith organs in the vestibular system and in zebrafish lateral line. Remarkably, GPR156-Gαi also instructs hair cell reversal in the auditory epithelium, despite a lack of mirror-image organization. Overall, our work demonstrates that conserved GPR156-Gαi signaling is integral to the framework that builds directional responses into mechanosensory epithelia.
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MESH Headings
- Animals
- Cell Polarity/genetics
- Epithelium/metabolism
- Female
- GTP-Binding Protein alpha Subunits, Gi-Go/genetics
- GTP-Binding Protein alpha Subunits, Gi-Go/metabolism
- Hair Cells, Auditory/cytology
- Hair Cells, Auditory/metabolism
- Homeodomain Proteins/genetics
- Homeodomain Proteins/metabolism
- Male
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Transgenic
- Microscopy, Confocal/methods
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Transcription Factors/genetics
- Transcription Factors/metabolism
- Zebrafish/metabolism
- Mice
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Affiliation(s)
- Katie S Kindt
- Section on Sensory Cell Development and Function, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
| | | | | | | | - Alisha Beirl
- Section on Sensory Cell Development and Function, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD, USA
| | | | - Basile Tarchini
- The Jackson Laboratory, Bar Harbor, ME, USA.
- Department of Medicine, Tufts University, Boston, MA, USA.
- Graduate School of Biomedical Science and Engineering (GSBSE), University of Maine, Orono, ME, USA.
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20
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Stabenau KA, Zimmermann MT, Mathison A, Zeighami A, Samuels TL, Chun RH, Papsin BC, McCormick ME, Johnston N, Kerschner JE. RNA Sequencing and Pathways Analyses of Middle Ear Epithelia From Patients With Otitis Media. Laryngoscope 2021; 131:2590-2597. [PMID: 33844317 DOI: 10.1002/lary.29551] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 03/04/2021] [Accepted: 03/23/2021] [Indexed: 01/24/2023]
Abstract
OBJECTIVES Otitis media (OM) is the most common pediatric diagnosis in the United States. However, our understanding of the molecular pathogenesis of OM remains relatively poor. Investigation of molecular pathways involved in OM may improve the understanding of this disease process and elucidate novel therapeutic targets. In this study, RNA sequencing (RNA-Seq) was used to discern cellular changes associated with OME compared to healthy middle ear epithelium (MEE). STUDY DESIGN Ex vivo case-control translational. METHODS Middle ear epithelia was collected from five pediatric patients diagnosed with OME undergoing tympanostomy tube placement and five otherwise healthy pediatric patients undergoing cochlear implantation. Specimens underwent RNA-Seq and pathways analyses. RESULTS A total of 1,292 genes exhibited differential expression in MEE from OME patients compared to controls including genes involved in inflammation, immune response to bacterial OM pathogens, mucociliary clearance, regulation of proliferation and transformation, and auditory cell differentiation. Top networks identified in OME were organismal injury and abnormalities, cell morphology, and auditory disease. Top Ingenuity canonical pathways identified were axonal guidance signaling, which contains genes associated with auditory development and disease and nicotine degradation II and III pathways. Associated upstream regulators included β-estradiol, dexamethasone, and G-protein-coupled estrogen receptor-1 (GPER1), which are associated with otoprotection or inflammation during insult. CONCLUSIONS RNA-Seq demonstrates differential gene expression in MEE from patients with OME compared to healthy controls with important implications for infection susceptibility, hearing loss, and a role for tobacco exposure in the development and/or severity of OME in pediatric patients. LEVEL OF EVIDENCE 4 Laryngoscope, 2021.
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Affiliation(s)
- Kaleigh A Stabenau
- Department of Otolaryngology and Communication Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin, U.S.A
| | - Michael T Zimmermann
- Bioinformatics Research and Development Laboratory, Genomic Sciences and Precision Medicine Center, Medical College of Wisconsin, Milwaukee, Wisconsin, U.S.A.,Clinical and Translational Science Institute, Medical College of Wisconsin, Milwaukee, Wisconsin, U.S.A
| | - Angela Mathison
- Bioinformatics Research and Development Laboratory, Genomic Sciences and Precision Medicine Center, Medical College of Wisconsin, Milwaukee, Wisconsin, U.S.A
| | - Atefeh Zeighami
- Bioinformatics Research and Development Laboratory, Genomic Sciences and Precision Medicine Center, Medical College of Wisconsin, Milwaukee, Wisconsin, U.S.A
| | - Tina L Samuels
- Department of Otolaryngology and Communication Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin, U.S.A
| | - Robert H Chun
- Department of Otolaryngology and Communication Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin, U.S.A
| | - Blake C Papsin
- Archie's Cochlear Implant Laboratory, Department of Otolaryngology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Michael E McCormick
- Department of Otolaryngology and Communication Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin, U.S.A
| | - Nikki Johnston
- Department of Otolaryngology and Communication Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin, U.S.A.,Department of Microbiology and Immunology, Medical College of Wisconsin, Milwaukee, Wisconsin, U.S.A
| | - Joseph E Kerschner
- Department of Otolaryngology and Communication Sciences, Medical College of Wisconsin, Milwaukee, Wisconsin, U.S.A
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21
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Ratzan EM, Moon AM, Deans MR. Fgf8 genetic labeling reveals the early specification of vestibular hair cell type in mouse utricle. Development 2020; 147:dev.192849. [PMID: 33046506 DOI: 10.1242/dev.192849] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 10/07/2020] [Indexed: 01/16/2023]
Abstract
FGF8 signaling plays diverse roles in inner ear development, acting at multiple stages from otic placode induction to cellular differentiation in the organ of Corti. As a secreted morphogen with diverse functions, Fgf8 expression is likely to be spatially restricted and temporally dynamic throughout inner ear development. We evaluated these characteristics using genetic labeling mediated by Fgf8 mcm gene-targeted mice and determined that Fgf8 expression is a specific and early marker of Type-I vestibular hair cell identity. Fgf8 mcm expression initiates at E11.5 in the future striolar region of the utricle, labeling hair cells following EdU birthdating, and demonstrates that sub-type identity is determined shortly after terminal mitosis. This early fate specification is not apparent using markers or morphological criteria that are not present before birth in the mouse. Although analyses of Fgf8 conditional knockout mice did not reveal developmental phenotypes, the restricted pattern of Fgf8 expression suggests that functionally redundant FGF ligands may contribute to vestibular hair cell differentiation and supports a developmental model in which Type-I and Type-II hair cells develop in parallel rather than from an intermediate precursor.
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Affiliation(s)
- Evan M Ratzan
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.,Interdepartmental Program in Neuroscience, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - Anne M Moon
- Departments of Molecular and Functional Genomics and Pediatrics, Weis Center for Research, Geisinger Clinic and Geisinger Commonwealth School of Medicine, Danville, PA 17822, USA.,Departments of Pediatrics and Human Genetics, University of Utah, Salt Lake City, UT 84112 USA
| | - Michael R Deans
- Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, UT 84112, USA .,Department of Surgery, Division of Otolaryngology, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
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22
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Tona Y, Wu DK. Live imaging of hair bundle polarity acquisition demonstrates a critical timeline for transcription factor Emx2. eLife 2020; 9:e59282. [PMID: 32965215 PMCID: PMC7535933 DOI: 10.7554/elife.59282] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 09/17/2020] [Indexed: 12/22/2022] Open
Abstract
Directional sensitivity of hair cells (HCs) is conferred by the aymmetric apical hair bundle, comprised of a kinocilium and stereocilia staircase. The mother centriole (MC) forms the base of the kinocilium and the stereocilia develop adjacent to it. Previously, we showed that transcription factor Emx2 reverses hair bundle orientation and its expression in the mouse vestibular utricle is restricted, resulting in two regions of opposite bundle orientation (Jiang et al., 2017). Here, we investigated establishment of opposite bundle orientation in embryonic utricles by live-imaging GFP-labeled centrioles in HCs. The daughter centriole invariably migrated ahead of the MC from the center to their respective peripheral locations in HCs. Comparing HCs between utricular regions, centriole trajectories were similar but they migrated toward opposite directions, suggesting that Emx2 pre-patterned HCs prior to centriole migration. Ectopic Emx2, however, reversed centriole trajectory within hours during a critical time-window when centriole trajectory was responsive to Emx2.
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Affiliation(s)
- Yosuke Tona
- National Institute on Deafness and Other Communication Disorders, National Institutes of HealthBethesdaUnited States
| | - Doris K Wu
- National Institute on Deafness and Other Communication Disorders, National Institutes of HealthBethesdaUnited States
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23
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LIN28B/ let-7 control the ability of neonatal murine auditory supporting cells to generate hair cells through mTOR signaling. Proc Natl Acad Sci U S A 2020; 117:22225-22236. [PMID: 32826333 DOI: 10.1073/pnas.2000417117] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Mechano-sensory hair cells within the inner ear cochlea are essential for the detection of sound. In mammals, cochlear hair cells are only produced during development and their loss, due to disease or trauma, is a leading cause of deafness. In the immature cochlea, prior to the onset of hearing, hair cell loss stimulates neighboring supporting cells to act as hair cell progenitors and produce new hair cells. However, for reasons unknown, such regenerative capacity (plasticity) is lost once supporting cells undergo maturation. Here, we demonstrate that the RNA binding protein LIN28B plays an important role in the production of hair cells by supporting cells and provide evidence that the developmental drop in supporting cell plasticity in the mammalian cochlea is, at least in part, a product of declining LIN28B-mammalian target of rapamycin (mTOR) activity. Employing murine cochlear organoid and explant cultures to model mitotic and nonmitotic mechanisms of hair cell generation, we show that loss of LIN28B function, due to its conditional deletion, or due to overexpression of the antagonistic miRNA let-7g, suppressed Akt-mTOR complex 1 (mTORC1) activity and renders young, immature supporting cells incapable of generating hair cells. Conversely, we found that LIN28B overexpression increased Akt-mTORC1 activity and allowed supporting cells that were undergoing maturation to de-differentiate into progenitor-like cells and to produce hair cells via mitotic and nonmitotic mechanisms. Finally, using the mTORC1 inhibitor rapamycin, we demonstrate that LIN28B promotes supporting cell plasticity in an mTORC1-dependent manner.
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24
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Abstract
The cochlea, a coiled structure located in the ventral region of the inner ear, acts as the primary structure for the perception of sound. Along the length of the cochlear spiral is the organ of Corti, a highly derived and rigorously patterned sensory epithelium that acts to convert auditory stimuli into neural impulses. The development of the organ of Corti requires a series of inductive events that specify unique cellular characteristics and axial identities along its three major axes. Here, we review recent studies of the cellular and molecular processes regulating several aspects of cochlear development, such as axial patterning, cochlear outgrowth and cellular differentiation. We highlight how the precise coordination of multiple signaling pathways is required for the successful formation of a complete organ of Corti.
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Affiliation(s)
- Elizabeth Carroll Driver
- Laboratory of Cochlear Development, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
| | - Matthew W Kelley
- Laboratory of Cochlear Development, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
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25
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Kozak EL, Palit S, Miranda-Rodríguez JR, Janjic A, Böttcher A, Lickert H, Enard W, Theis FJ, López-Schier H. Epithelial Planar Bipolarity Emerges from Notch-Mediated Asymmetric Inhibition of Emx2. Curr Biol 2020; 30:1142-1151.e6. [PMID: 32109392 DOI: 10.1016/j.cub.2020.01.027] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 11/28/2019] [Accepted: 01/08/2020] [Indexed: 12/24/2022]
Abstract
Most plane-polarized tissues are formed by identically oriented cells [1, 2]. A notable exception occurs in the vertebrate vestibular system and lateral-line neuromasts, where mechanosensory hair cells orient along a single axis but in opposite directions to generate bipolar epithelia [3-5]. In zebrafish neuromasts, pairs of hair cells arise from the division of a non-sensory progenitor [6, 7] and acquire opposing planar polarity via the asymmetric expression of the polarity-determinant transcription factor Emx2 [8-11]. Here, we reveal the initial symmetry-breaking step by decrypting the developmental trajectory of hair cells using single-cell RNA sequencing (scRNA-seq), diffusion pseudotime analysis, lineage tracing, and mutagenesis. We show that Emx2 is absent in non-sensory epithelial cells, begins expression in hair-cell progenitors, and is downregulated in one of the sibling hair cells via signaling through the Notch1a receptor. Analysis of Emx2-deficient specimens, in which every hair cell adopts an identical direction, indicates that Emx2 asymmetry does not result from auto-regulatory feedback. These data reveal a two-tiered mechanism by which the symmetric monodirectional ground state of the epithelium is inverted by deterministic initiation of Emx2 expression in hair-cell progenitors and a subsequent stochastic repression of Emx2 in one of the sibling hair cells breaks directional symmetry to establish planar bipolarity.
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Affiliation(s)
- Eva L Kozak
- Research Unit of Sensory Biology & Organogenesis, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764 Neuherberg, Germany
| | - Subarna Palit
- Institute of Computational Biology, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764 Neuherberg, Germany
| | - Jerónimo R Miranda-Rodríguez
- Research Unit of Sensory Biology & Organogenesis, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764 Neuherberg, Germany
| | - Aleksandar Janjic
- Department Biology II, Anthropology and Human Genomics, Ludwig Maximilians University of Munich, Großhaderner Straße 2, 82152 Martinsried, Germany
| | - Anika Böttcher
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764 Neuherberg, Germany; German Center for Diabetes Research, Ingolstädter Landstraße 1, 85764 Neuherberg, Germany; Institute of Stem Cell Research, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764 Neuherberg, Germany
| | - Heiko Lickert
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764 Neuherberg, Germany; German Center for Diabetes Research, Ingolstädter Landstraße 1, 85764 Neuherberg, Germany; Institute of Stem Cell Research, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764 Neuherberg, Germany; School of Medicine, Technical University of Munich, Ismaninger Straße 22, 81675 Munich, Germany
| | - Wolfgang Enard
- Department Biology II, Anthropology and Human Genomics, Ludwig Maximilians University of Munich, Großhaderner Straße 2, 82152 Martinsried, Germany
| | - Fabian J Theis
- Institute of Computational Biology, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764 Neuherberg, Germany; School of Life Sciences Weihenstephan, Technical University of Munich, Alte Akademie, 85354 Freising, Germany; Department of Mathematics, Technical University of Munich, Boltzmannstraße 3, 85748 Garching, Germany
| | - Hernán López-Schier
- Research Unit of Sensory Biology & Organogenesis, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764 Neuherberg, Germany.
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Tarchini B, Lu X. New insights into regulation and function of planar polarity in the inner ear. Neurosci Lett 2019; 709:134373. [PMID: 31295539 PMCID: PMC6732021 DOI: 10.1016/j.neulet.2019.134373] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 07/02/2019] [Accepted: 07/06/2019] [Indexed: 12/18/2022]
Abstract
Acquisition of cell polarity generates signaling and cytoskeletal asymmetry and thus underpins polarized cell behaviors during tissue morphogenesis. In epithelial tissues, both apical-basal polarity and planar polarity, which refers to cell polarization along an axis orthogonal to the apical-basal axis, are essential for epithelial morphogenesis and function. A prime example of epithelial planar polarity can be found in the auditory sensory epithelium (or organ of Corti, OC). Sensory hair cells, the sound receptors, acquire a planar polarized apical cytoskeleton which is uniformely oriented along an axis orthogonal to the longitudinal axis of the cochlear duct. Both cell-intrinsic and tissue-level planar polarity are necessary for proper perception of sound. Here we review recent insights into the novel roles and mechanisms of planar polarity signaling gained from genetic analysis in mice, focusing mainly on the OC but also with some discussions on the vestibular sensory epithelia.
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Affiliation(s)
- Basile Tarchini
- The Jackson Laboratory, Bar Harbor, ME, 04609, USA; Department of Medicine, Tufts University, Boston, 02111, MA, USA; Graduate School of Biomedical Science and Engineering (GSBSE), University of Maine, Orono, 04469, ME, USA.
| | - Xiaowei Lu
- Department of Cell Biology, University of Virginia Health System, Charlottesville, VA, 22908, USA.
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Par3 is essential for the establishment of planar cell polarity of inner ear hair cells. Proc Natl Acad Sci U S A 2019; 116:4999-5008. [PMID: 30814219 DOI: 10.1073/pnas.1816333116] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
In the inner ear sensory epithelia, stereociliary hair bundles atop sensory hair cells are mechanosensory apparatus with planar polarized structure and orientation. This is established during development by the concerted action of tissue-level, intercellular planar cell polarity (PCP) signaling and a hair cell-intrinsic, microtubule-mediated machinery. However, how various polarity signals are integrated during hair bundle morphogenesis is poorly understood. Here, we show that the conserved cell polarity protein Par3 is essential for planar polarization of hair cells. Par3 deletion in the inner ear disrupted cochlear outgrowth, hair bundle orientation, kinocilium positioning, and basal body planar polarity, accompanied by defects in the organization and cortical attachment of hair cell microtubules. Genetic mosaic analysis revealed that Par3 functions both cell-autonomously and cell-nonautonomously to regulate kinocilium positioning and hair bundle orientation. At the tissue level, intercellular PCP signaling regulates the asymmetric localization of Par3, which in turn maintains the asymmetric localization of the core PCP protein Vangl2. Mechanistically, Par3 interacts with and regulates the localization of Tiam1 and Trio, which are guanine nucleotide exchange factors (GEFs) for Rac, thereby stimulating Rac-Pak signaling. Finally, constitutively active Rac1 rescued the PCP defects in Par3-deficient cochleae. Thus, a Par3-GEF-Rac axis mediates both tissue-level and hair cell-intrinsic PCP signaling.
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28
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Groves JA, Gillman C, DeLay CN, Kroll TT. Identification of Novel Binding Partners for Transcription Factor Emx2. Protein J 2019; 38:2-11. [PMID: 30628007 DOI: 10.1007/s10930-019-09810-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The mammalian homolog of Drosophila empty spiracles 2 (Emx2) is a homeobox transcription factor that plays central roles in early development of the inner ear, pelvic and shoulder girdles, cerebral cortex, and urogenital organs. The role for Emx2 is best understood within the context of the development of the neocortical region of the cortex, where Emx2 is expressed in a high posterior-medial to low anterior-lateral gradient that regulates the partitioning of the neocortex into different functional fields that perform discrete computational tasks. Despite several lines of evidence demonstrating an Emx2 concentration-dependent mechanism for establishing functional areas within the developing neocortex, little is known about how Emx2 physically carries out this role. Although several binding partners for Emx2 have been identified (including Sp8, eIF4E, and Pbx1), no screens have been used to identify potential protein binding partners for this protein. We utilized a yeast two-hybrid screen using a library constructed from embryonic mouse cDNA in an attempt to identify novel binding partners for Emx2. This initial screen isolated two potential Emx2-binding partner proteins, Cnot6l and QkI-7. These novel Emx2-binding proteins are involved in multiple levels of mRNA metabolism that including splicing, mRNA export, translation, and destruction, thus making them interesting targets for further study.
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Affiliation(s)
- Jennifer A Groves
- Department of Chemistry, Central Washington University, 400 E. University Way, Ellensburg, WA, 98929-7539, USA
| | - Cody Gillman
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 157 Broad Center, M/C, Pasadena, USA
| | - Cierra N DeLay
- Department of Chemistry, Central Washington University, 400 E. University Way, Ellensburg, WA, 98929-7539, USA
| | - Todd T Kroll
- Department of Chemistry, Central Washington University, 400 E. University Way, Ellensburg, WA, 98929-7539, USA.
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Pickett SB, Raible DW. Water Waves to Sound Waves: Using Zebrafish to Explore Hair Cell Biology. J Assoc Res Otolaryngol 2019; 20:1-19. [PMID: 30635804 DOI: 10.1007/s10162-018-00711-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 12/19/2018] [Indexed: 01/09/2023] Open
Abstract
Although perhaps best known for their use in developmental studies, over the last couple of decades, zebrafish have become increasingly popular model organisms for investigating auditory system function and disease. Like mammals, zebrafish possess inner ear mechanosensory hair cells required for hearing, as well as superficial hair cells of the lateral line sensory system, which mediate detection of directional water flow. Complementing mammalian studies, zebrafish have been used to gain significant insights into many facets of hair cell biology, including mechanotransduction and synaptic physiology as well as mechanisms of both hereditary and acquired hair cell dysfunction. Here, we provide an overview of this literature, highlighting some of the particular advantages of using zebrafish to investigate hearing and hearing loss.
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Affiliation(s)
- Sarah B Pickett
- Department of Biological Structure, University of Washington, Health Sciences Building H-501, 1959 NE Pacific Street, Box 357420, Seattle, WA, 98195-7420, USA
- Graduate Program in Neuroscience, University of Washington, 1959 NE Pacific Street, Box 357270, Seattle, WA, 98195-7270, USA
| | - David W Raible
- Department of Biological Structure, University of Washington, Health Sciences Building H-501, 1959 NE Pacific Street, Box 357420, Seattle, WA, 98195-7420, USA.
- Graduate Program in Neuroscience, University of Washington, 1959 NE Pacific Street, Box 357270, Seattle, WA, 98195-7270, USA.
- Virginia Merrill Bloedel Hearing Research Center, University of Washington, 1701 NE Columbia Rd, Box 357923, Seattle, WA, 98195-7923, USA.
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30
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Hair cell identity establishes labeled lines of directional mechanosensation. PLoS Biol 2018; 16:e2004404. [PMID: 30024872 PMCID: PMC6067750 DOI: 10.1371/journal.pbio.2004404] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 07/31/2018] [Accepted: 07/02/2018] [Indexed: 11/19/2022] Open
Abstract
Directional mechanoreception by hair cells is transmitted to the brain via afferent neurons to enable postural control and rheotaxis. Neuronal tuning to individual directions of mechanical flow occurs when each peripheral axon selectively synapses with multiple hair cells of identical planar polarization. How such mechanosensory labeled lines are established and maintained remains unsolved. Here, we use the zebrafish lateral line to reveal that asymmetric activity of the transcription factor Emx2 diversifies hair cell identity to instruct polarity-selective synaptogenesis. Unexpectedly, presynaptic scaffolds and coherent hair cell orientation are dispensable for synaptic selectivity, indicating that epithelial planar polarity and synaptic partner matching are separable. Moreover, regenerating axons recapitulate synapses with hair cells according to Emx2 expression but not global orientation. Our results identify a simple cellular algorithm that solves the selectivity task even in the presence of noise generated by the frequent receptor cell turnover. They also suggest that coupling connectivity patterns to cellular identity rather than polarity relaxes developmental and evolutionary constraints to innervation of organs with differing orientation. Mechanosensory systems are essential for maintaining posture, gaze, and body orientation during locomotion. Such stability requires a coherent representation in the brain of the location and movement of mechanical stimuli. In fishes, mechanical stimuli at a given position activate direction-sensitive receptors called hair cells that are oriented with polarized directionality. These hair cells stimulate neurons that selectively connect with them based on polarity. We have addressed how neurons target hair cells based on polarity during development of the mechanosensory lateral line system in zebrafish. We show that neurons selectively connect based on the expression pattern of the transcription factor Emx2 in hair cells. We find that the lateral line can maintain directionality after damage and regeneration. Our data suggest a cellular mechanism that controls the formation, maintenance, and regeneration of labeled lines to enable directional mechanosensation.
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31
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Spatiotemporal coordination of cellular differentiation and tissue morphogenesis in organ of Corti development. Med Mol Morphol 2018. [PMID: 29536272 DOI: 10.1007/s00795-018-0185-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The organ of Corti, an acoustic sensory organ, is a specifically differentiated epithelium of the cochlear duct, which is a part of the membranous labyrinth in the inner ear. Cells in the organ of Corti are generally classified into two kinds; hair cells, which transduce the mechanical stimuli of sound to the cell membrane electrical potential differences, and supporting cells. These cells emerge from homogeneous prosensory epithelium through cell fate determination and differentiation. In the organ of Corti organogenesis, cell differentiation and the rearrangement of their position proceed in parallel, resulting in a characteristic alignment of mature hair cells and supporting cells. Recently, studies have focused on the signaling molecules and transcription factors that regulate cell fate determination and differentiation processes. In comparison, less is known about the mechanism of the formation of the tissue architecture; however, this is important in the morphogenesis of the organ of Corti. Thus, this review will introduce previous findings that focus on how cell fate determination, cell differentiation, and whole tissue morphogenesis proceed in a spatiotemporally and finely coordinated manner. This overview provides an insight into the regulatory mechanisms of the coordination in the developing organ of Corti.
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Stoller ML, Roman O, Deans MR. Domineering non-autonomy in Vangl1;Vangl2 double mutants demonstrates intercellular PCP signaling in the vertebrate inner ear. Dev Biol 2018; 437:17-26. [PMID: 29510119 DOI: 10.1016/j.ydbio.2018.02.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 02/28/2018] [Accepted: 02/28/2018] [Indexed: 11/26/2022]
Abstract
The organization of polarized stereociliary bundles is critical for the function of the inner ear sensory receptor hair cells that detect sound and motion, and these cells present a striking example of Planar Cell Polarity (PCP); the coordinated orientation of polarized structures within the plane of an epithelium. PCP is best understood in Drosophila where the essential genes regulating PCP were first discovered, and functions for the core PCP proteins encoded by these genes have been deciphered through phenotypic analysis of core PCP gene mutants. One illuminating phenotype is the domineering non-autonomy that is observed where abrupt disruptions in PCP signaling impacts the orientation of neighboring wild type cells, because this demonstrates local intercellular signaling mediated by the core PCP proteins. Using Emx2-Cre to generate an analogous mutant boundary in the mouse inner ear, we disrupted vertebrate PCP signaling in Vangl1;Vangl2 conditional knockouts. Due to unique aspects of vestibular anatomy, core PCP protein distribution along the mutant boundary generated in the utricle resembles the proximal side of vang mutant clones in the Drosophila wing, while the boundary in the saccule resembles and the distal side. Consistent with these protein distributions, a domineering non-autonomy phenotype occurs along the Emx2-Cre boundary in the mutant utricle that does not occur in the saccule. These results further support the hypothesis that core PCP function is conserved in vertebrates by demonstrating intercellular PCP signaling in the sensory epithelia of the mouse ear.
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Affiliation(s)
- Michelle L Stoller
- Department of Surgery, Division of Otolaryngology, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Orvelin Roman
- Department of Surgery, Division of Otolaryngology, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
| | - Michael R Deans
- Department of Surgery, Division of Otolaryngology, University of Utah School of Medicine, Salt Lake City, UT 84132, USA; Department of Neurobiology&Anatomy, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
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Hatch K, Pabon A, DiMario JX. EMX2 activates slow myosin heavy chain 2 gene expression in embryonic muscle fibers. Mech Dev 2017; 147:8-16. [PMID: 28673691 DOI: 10.1016/j.mod.2017.06.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 06/23/2017] [Accepted: 06/25/2017] [Indexed: 10/19/2022]
Abstract
Avian myogenesis is partly characterized by commitment of distinct myoblast cell lineages to the formation of specific muscle fiber types. Previous studies have identified the transcription factor EMX2 as a regulator of slow myosin heavy chain 2 (MyHC2) gene expression in fast/slow primary muscle fibers. We report here the interaction of EMX2 with the slow MyHC2 transcriptional regulatory region in fast/slow embryonic muscle fibers. Promoter activity and electromobility shift assays localized the site of interaction of EMX2 with the slow MyHC2 gene within a defined binding site located between 3336 and 3326bp from the 3' end of the cloned slow MyHC2 DNA containing the transcriptional regulatory region. Using clonally-derived myoblasts stably committed to the formation of fast/slow muscle fibers, we also report the effect of altered EMX2 gene expression on genome-wide gene expression within these myoblasts. Increased EMX2 gene expression in fast/slow myoblasts caused altered gene expression of 1185 genes, indicating that EMX2 plays a central role in the gene expression profile of embryonic myoblasts.
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Affiliation(s)
- Kristina Hatch
- School of Graduate and Postdoctoral Studies and Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL, USA
| | - Amanda Pabon
- School of Graduate and Postdoctoral Studies and Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL, USA
| | - Joseph X DiMario
- School of Graduate and Postdoctoral Studies and Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL, USA.
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34
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Jiang T, Kindt K, Wu DK. Transcription factor Emx2 controls stereociliary bundle orientation of sensory hair cells. eLife 2017; 6. [PMID: 28266911 PMCID: PMC5388538 DOI: 10.7554/elife.23661] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2016] [Accepted: 03/04/2017] [Indexed: 12/13/2022] Open
Abstract
The asymmetric location of stereociliary bundle (hair bundle) on the apical surface of mechanosensory hair cells (HCs) dictates the direction in which a given HC can respond to cues such as sound, head movements, and water pressure. Notably, vestibular sensory organs of the inner ear, the maculae, exhibit a line of polarity reversal (LPR) across which, hair bundles are polarized in a mirror-image pattern. Similarly, HCs in neuromasts of the zebrafish lateral line system are generated as pairs, and two sibling HCs develop opposite hair bundle orientations. Within these sensory organs, expression of the transcription factor Emx2 is restricted to only one side of the LPR in the maculae or one of the two sibling HCs in neuromasts. Emx2 mediates hair bundle polarity reversal in these restricted subsets of HCs and generates the mirror-image pattern of the sensory organs. Downstream effectors of Emx2 control bundle polarity cell-autonomously via heterotrimeric G proteins.
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Affiliation(s)
- Tao Jiang
- Program in Neuroscience and Cognitive Science, University of Maryland, College Park, United States.,Laboratory of Molecular Biology, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, United States
| | - Katie Kindt
- Section on Sensory Cell Development, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, United States
| | - Doris K Wu
- Laboratory of Molecular Biology, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, United States
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35
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Durruthy-Durruthy R, Gottlieb A, Hartman BH, Waldhaus J, Laske RD, Altman R, Heller S. Reconstruction of the mouse otocyst and early neuroblast lineage at single-cell resolution. Cell 2014; 157:964-78. [PMID: 24768691 PMCID: PMC4051200 DOI: 10.1016/j.cell.2014.03.036] [Citation(s) in RCA: 113] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Revised: 02/03/2014] [Accepted: 03/12/2014] [Indexed: 01/24/2023]
Abstract
The otocyst harbors progenitors for most cell types of the mature inner ear. Developmental lineage analyses and gene expression studies suggest that distinct progenitor populations are compartmentalized to discrete axial domains in the early otocyst. Here, we conducted highly parallel quantitative RT-PCR measurements on 382 individual cells from the developing otocyst and neuroblast lineages to assay 96 genes representing established otic markers, signaling-pathway-associated transcripts, and novel otic-specific genes. By applying multivariate cluster, principal component, and network analyses to the data matrix, we were able to readily distinguish the delaminating neuroblasts and to describe progressive states of gene expression in this population at single-cell resolution. It further established a three-dimensional model of the otocyst in which each individual cell can be precisely mapped into spatial expression domains. Our bioinformatic modeling revealed spatial dynamics of different signaling pathways active during early neuroblast development and prosensory domain specification.
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Affiliation(s)
- Robert Durruthy-Durruthy
- Department of Otolaryngology, Head & Neck Surgery and Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Assaf Gottlieb
- Departments of Bioengineering and Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Byron H Hartman
- Department of Otolaryngology, Head & Neck Surgery and Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Jörg Waldhaus
- Department of Otolaryngology, Head & Neck Surgery and Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Roman D Laske
- Department of Otolaryngology, Head & Neck Surgery and Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Russ Altman
- Departments of Bioengineering and Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Stefan Heller
- Department of Otolaryngology, Head & Neck Surgery and Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA.
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36
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Fukuda T, Kominami K, Wang S, Togashi H, Hirata KI, Mizoguchi A, Rikitake Y, Takai Y. Aberrant cochlear hair cell attachments caused by Nectin-3 deficiency result in hair bundle abnormalities. Development 2014; 141:399-409. [PMID: 24381198 DOI: 10.1242/dev.094995] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The organ of Corti consists of sensory hair cells (HCs) interdigitated with nonsensory supporting cells (SCs) to form a checkerboard-like cellular pattern. HCs are equipped with hair bundles on their apical surfaces. We previously reported that cell-adhesive nectins regulate the checkerboard-like cellular patterning of HCs and SCs in the mouse auditory epithelium. Nectin-1 and -3 are differentially expressed in normal HCs and SCs, respectively, and in Nectin-3-deficient mice a number of HCs are aberrantly attached to each other. We show here that these aberrantly attached HCs in Nectin-3-deficient mice, but not unattached ones, show disturbances of the orientation and morphology of the hair bundles and the positioning of the kinocilium, with additional abnormal localisation of cadherin-catenin complexes and the apical-basal polarity proteins Pals1 and Par-3. These results indicate that, owing to the loss of Nectin-3, hair cells contact each other inappropriately and form abnormal junctions, ultimately resulting in abnormal hair bundle orientation and morphology.
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Affiliation(s)
- Terunobu Fukuda
- Division of Molecular and Cellular Biology, Department of Biochemistry and Molecular Biology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
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37
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Sensational placodes: neurogenesis in the otic and olfactory systems. Dev Biol 2014; 389:50-67. [PMID: 24508480 PMCID: PMC3988839 DOI: 10.1016/j.ydbio.2014.01.023] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Revised: 01/27/2014] [Accepted: 01/28/2014] [Indexed: 11/22/2022]
Abstract
For both the intricate morphogenetic layout of the sensory cells in the ear and the elegantly radial arrangement of the sensory neurons in the nose, numerous signaling molecules and genetic determinants are required in concert to generate these specialized neuronal populations that help connect us to our environment. In this review, we outline many of the proteins and pathways that play essential roles in the differentiation of otic and olfactory neurons and their integration into their non-neuronal support structures. In both cases, well-known signaling pathways together with region-specific factors transform thickened ectodermal placodes into complex sense organs containing numerous, diverse neuronal subtypes. Olfactory and otic placodes, in combination with migratory neural crest stem cells, generate highly specialized subtypes of neuronal cells that sense sound, position and movement in space, odors and pheromones throughout our lives.
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38
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Weimer K, Theobald J, Campbell KS, Esser KA, DiMario JX. Genome-wide expression analysis and EMX2 gene expression in embryonic myoblasts committed to diverse skeletal muscle fiber type fates. Dev Dyn 2013; 242:1001-20. [PMID: 23703830 PMCID: PMC3763492 DOI: 10.1002/dvdy.23988] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Revised: 04/24/2013] [Accepted: 05/07/2013] [Indexed: 11/07/2022] Open
Abstract
BACKGROUND Primary skeletal muscle fibers form during embryonic development and are characterized as fast or slow fibers based on contractile protein gene expression. Different avian primary muscle fiber types arise from myoblast lineages committed to formation of diverse fiber types. To understand the basis of embryonic muscle fiber type diversity and the distinct myoblast lineages that generate this diversity, gene expression analyses were conducted on differentiated muscle fiber types and their respective myoblast precursor lineages. RESULTS Embryonic fast muscle fibers preferentially expressed 718 genes, and embryonic fast/slow muscle fibers differentially expressed 799 genes. Fast and fast/slow myoblast lineages displayed appreciable diversity in their gene expression profiles, indicating diversity of precursor myoblasts. Several genes, including the transcriptional regulator EMX2, were differentially expressed in both fast/slow myoblasts and muscle fibers vs. fast myoblasts and muscle fibers. EMX2 was localized to nuclei of fast/slow myoblasts and muscle fibers and was not detected in fast lineage cells. Furthermore, EMX2 overexpression and knockdown studies indicated that EMX2 is a positive transcriptional regulator of the slow myosin heavy chain 2 (MyHC2) gene promoter activity in fast/slow muscle fibers. CONCLUSIONS These results indicate the presence of distinct molecular signatures that characterize diverse embryonic myoblast lineages before differentiation.
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Affiliation(s)
- Kristina Weimer
- Rosalind Franklin University of Medicine and Science, School of Graduate and Postdoctoral Studies, Department of Cell Biology and Anatomy, 3333 Green Bay Road, North Chicago, IL 60064
| | - Jillian Theobald
- Rosalind Franklin University of Medicine and Science, School of Graduate and Postdoctoral Studies, Department of Cell Biology and Anatomy, 3333 Green Bay Road, North Chicago, IL 60064
| | - Kenneth S. Campbell
- Center for Muscle Biology, Department of Physiology, University of Kentucky, Lexington, KY 40536
| | - Karyn A. Esser
- Center for Muscle Biology, Department of Physiology, University of Kentucky, Lexington, KY 40536
| | - Joseph X. DiMario
- Rosalind Franklin University of Medicine and Science, School of Graduate and Postdoctoral Studies, Department of Cell Biology and Anatomy, 3333 Green Bay Road, North Chicago, IL 60064
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Fritzsch B, Pan N, Jahan I, Duncan JS, Kopecky BJ, Elliott KL, Kersigo J, Yang T. Evolution and development of the tetrapod auditory system: an organ of Corti-centric perspective. Evol Dev 2013; 15:63-79. [PMID: 23331918 DOI: 10.1111/ede.12015] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The tetrapod auditory system transmits sound through the outer and middle ear to the organ of Corti or other sound pressure receivers of the inner ear where specialized hair cells translate vibrations of the basilar membrane into electrical potential changes that are conducted by the spiral ganglion neurons to the auditory nuclei. In other systems, notably the vertebrate limb, a detailed connection between the evolutionary variations in adaptive morphology and the underlying alterations in the genetic basis of development has been partially elucidated. In this review, we attempt to correlate evolutionary and partially characterized molecular data into a cohesive perspective of the evolution of the mammalian organ of Corti out of the tetrapod basilar papilla. We propose a stepwise, molecularly partially characterized transformation of the ancestral, vestibular developmental program of the vertebrate ear. This review provides a framework to decipher both discrete steps in development and the evolution of unique functional adaptations of the auditory system. The combined analysis of evolution and development establishes a powerful cross-correlation where conclusions derived from either approach become more meaningful in a larger context which is not possible through exclusively evolution or development centered perspectives. Selection may explain the survival of the fittest auditory system, but only developmental genetics can explain the arrival of the fittest auditory system. [Modified after (Wagner 2011)].
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Affiliation(s)
- Bernd Fritzsch
- Department of Biology, University of Iowa, CLAS, 143 BB, Iowa City, IA, 52242, USA. bernd‐
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40
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Abstract
Sensory hair cells are exquisitely sensitive vertebrate mechanoreceptors that mediate the senses of hearing and balance. Understanding the factors that regulate the development of these cells is important, not only to increase our understanding of ear development and its functional physiology but also to shed light on how these cells may be replaced therapeutically. In this review, we describe the signals and molecular mechanisms that initiate hair cell development in vertebrates, with particular emphasis on the transcription factor Atoh1, which is both necessary and sufficient for hair cell development. We then discuss recent findings on how microRNAs may modulate the formation and maturation of hair cells. Last, we review recent work on how hair cells are regenerated in many vertebrate groups and the factors that conspire to prevent this regeneration in mammals.
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Affiliation(s)
- Andrew K Groves
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA.
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Deans MR. A balance of form and function: planar polarity and development of the vestibular maculae. Semin Cell Dev Biol 2013; 24:490-8. [PMID: 23507521 DOI: 10.1016/j.semcdb.2013.03.001] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Revised: 01/04/2013] [Accepted: 03/04/2013] [Indexed: 02/02/2023]
Abstract
The mechanosensory hair cells of the inner ear have emerged as one of the primary models for studying the development of planar polarity in vertebrates. Planar polarity is the polarized organization of cells or cellular structures in the plane of an epithelium. For hair cells, planar polarity is manifest at the subcellular level in the polarized organization of the stereociliary bundle and at the cellular level in the coordinated orientation of stereociliary bundles between adjacent cells. This latter organization is commonly called Planar Cell Polarity and has been described in the greatest detail for auditory hair cells of the cochlea. A third level of planar polarity, referred to as tissue polarity, occurs in the utricular and saccular maculae; two inner ear sensory organs that use hair cells to detect linear acceleration and gravity. In the utricle and saccule hair cells are divided between two groups that have opposite stereociliary bundle polarities and, as a result, are able to detect movements in opposite directions. Thus vestibular hair cells are a unique model system for studying planar polarity because polarization develops at three different anatomical scales in the same sensory organ. Moreover the system has the potential to be used to dissect functional interactions between molecules regulating planar polarity at each of the three levels. Here the significance of planar polarity on vestibular system function will be discussed, and the molecular mechanisms associated with development of planar polarity at each anatomical level will be reviewed. Additional aspects of planar polarity that are unique to the vestibular maculae will also be introduced.
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Affiliation(s)
- Michael R Deans
- The Department of Otolaryngology, Head and Neck Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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42
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Abstract
Basic helix-loop-helix (bHLH) transcription factors (TFs) are crucial for inner ear neurosensory development. The proneural TF Atoh1 regulates the differentiation of hair cells (HCs) whereas Neurog1 and Neurod1 regulate specification and differentiation of neurons, respectively, but also affect HC development. Expression of Delta and Jagged ligands in nascent HCs and Notch receptors in supporting cells induce supporting cell differentiation through the regulation of neurogenic bHLH TFs (such as Hes1, Hes5) and suppression of limited Atoh1 expression. In sensorineural hearing loss, HCs are lost followed by supporting cells and progressive degeneration of neurons, at least in rodents. Regaining complete hearing may require reconstituting the organ of Corti from scratch, including the two types of HCs, inner and outer hair cells with the precise sorting of two types of afferent (type I and II) and efferent (lateral and medial olivo-cochlear) innervation. We review effects of bHLH TF dosage and their cross-regulation to differentiate HC types in the organ of Corti. We categorize findings of specific gene expressions in HCs: 1. as markers without meaning for the regeneration task, 2. as stabilizers who are needed to maintain or complete differentiation, and 3. as decision-making genes, expressed and acting early enough to be useful in this process. Only one TF has been characterized that fits the last aspect: Atoh1. We propose that temporal and intensity variations of Atoh1 are naturally modulated to differentiate specific types of HCs. Importantly, the molecular means to modify the Atoh1 expression are at least partially understood and can be readily implemented in the attempts to regenerate specific types of HCs.
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43
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Schimmang T. Transcription factors that control inner ear development and their potential for transdifferentiation and reprogramming. Hear Res 2012; 297:84-90. [PMID: 23159917 DOI: 10.1016/j.heares.2012.11.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Revised: 10/23/2012] [Accepted: 11/05/2012] [Indexed: 12/17/2022]
Abstract
Transcription factors (TFs) participate during various processes throughout inner ear development such as induction, morphogenesis and determination of cell fate and differentiation. The analysis of mouse mutants has been essential to define the requirement of different members of TF families during these processes. Next to their roles during normal development TFs have also been tested for their capacity to induce differentiation or reprogram cells upon misexpression. Recently the capacity of TFs to transdifferentiate easily accessible cells such as fibroblasts to highly specialized cell types has opened a new pathway for regenerative therapies. In this review the influence of TFs acting during different phases and processes of inner ear development will be summarized. A special focus will be given to TFs with a potential to reprogram or transdifferentiate cells to sensory cell types of the inner ear such as hair cells or neurons and thus may form part of future protocols directed to generate replacement cells in a clinical context.
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Affiliation(s)
- Thomas Schimmang
- Instituto de Biología y Genética Molecular, Universidad de Valladolid y Consejo Superior de Investigaciones Científicas, C/Sanz y Forés 3, E-47003 Valladolid, Spain.
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Pan N, Kopecky B, Jahan I, Fritzsch B. Understanding the evolution and development of neurosensory transcription factors of the ear to enhance therapeutic translation. Cell Tissue Res 2012; 349:415-32. [PMID: 22688958 DOI: 10.1007/s00441-012-1454-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Accepted: 05/18/2012] [Indexed: 01/08/2023]
Abstract
Reconstructing a functional organ of Corti is the ultimate target towards curing hearing loss. Despite the impressive technical gains made over the last few years, many complications remain ahead for the two main restoration avenues: in vitro transformation of pluripotent cells into hair cell-like cells and adenovirus-mediated gene therapy. Most notably, both approaches require a more complete understanding of the molecular networks that ensure specific cell types form in the correct places to allow proper function of the restored organ of Corti. Important to this understanding are the basic helix-loop-helix (bHLH) transcription factors (TFs) that are highly diverse and serve to increase functional complexity but their evolutionary implementation in the inner ear neurosensory development is less conspicuous. To this end, we review the evolutionary and developmentally dynamic interactions of the three bHLH TFs that have been identified as the main players in neurosensory evolution and development, Neurog1, Neurod1 and Atoh1. These three TFs belong to the neurogenin/atonal family and evolved from a molecular precursor that likely regulated single sensory cell development in the ectoderm of metazoan ancestors but are now also expressed in other parts of the body, including the brain. They interact extensively via intracellular and intercellular cross-regulation to establish the two main neurosensory cell types of the ear, the hair cells and sensory neurons. Furthermore, the level and duration of their expression affect the specification of hair cell subtypes (inner hair cells vs. outer hair cells). We propose that appropriate manipulation of these TFs through their characterized binding sites may offer a solution by itself, or in conjunction with the two other approaches currently pursued by others, to restore the organ of Corti.
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Affiliation(s)
- Ning Pan
- Department of Biology, University of Iowa, College of Liberal Arts and Sciences, Iowa City, IA 52242, USA
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45
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Abstract
The inner ears of vertebrates represent one of the most striking examples of planar cell polarity (PCP). Populations of directionally sensitive mechanosensory hair cells develop actin-based stereociliary bundles that are uniformly oriented. Analysis of perturbations in bundle polarity in mice with mutations in Vangl2 formed the basis for the initial demonstration of conservation of the PCP signaling pathway in vertebrates. Subsequent studies have demonstrated roles for other "core" PCP genes, such as Frizzled, Disheveled, and Celsr, and for identifying novel PCP molecules such as Scribble and Ptk7. In addition, the demonstration of hearing deficits in humans with mutations in cilia genes combined with analysis of PCP defects in mice with ciliary deletion has implicated the cilia as an important modulator of hair cell polarization. Finally, the presence of shortened cochleae in many PCP mouse mutants has revealed an additional role for the PCP pathway in the development of the auditory system.
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Affiliation(s)
- Helen May-Simera
- Laboratory of Cochlear Development, NIDCD, NIH, Bethesda, Maryland, USA
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46
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Eatock RA, Songer JE. Vestibular hair cells and afferents: two channels for head motion signals. Annu Rev Neurosci 2011; 34:501-34. [PMID: 21469959 DOI: 10.1146/annurev-neuro-061010-113710] [Citation(s) in RCA: 169] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Vestibular epithelia of the inner ear detect head motions over a wide range of amplitudes and frequencies. In mammals, afferent nerve fibers from central and peripheral zones of vestibular epithelia form distinct populations with different response dynamics and spike timing. Central-zone afferents are large, fast conduits for phasic signals encoded in irregular spike trains. The finer afferents from peripheral zones conduct more slowly and encode more tonic, linear signals in highly regular spike trains. The hair cells are also of two types, I and II, but the two types do not correspond directly to the two afferent populations. Zonal differences in afferent response dynamics may arise at multiple stages, including mechanoelectrical transduction, voltage-gated channels in hair cells and afferents, afferent transmission at calyceal and bouton synapses, and spike generation in regular and irregular afferents. In contrast, zonal differences in spike timing may depend more simply on the selective expression of low-voltage-activated ion channels by irregular afferents.
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Affiliation(s)
- Ruth Anne Eatock
- Department of Otology and Laryngology, Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02114, USA.
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Dawe CE, Kooistra MK, Fairbridge NA, Pisio AC, McDermid HE. Role of chromatin remodeling gene Cecr2 in neurulation and inner ear development. Dev Dyn 2011; 240:372-83. [PMID: 21246654 DOI: 10.1002/dvdy.22547] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The loss of Cecr2, which encodes a chromatin remodeling protein, has been associated with the neural tube defect (NTD) exencephaly and open eyelids in mice. Here, we show that two independent mutations of Cecr2 are also associated with specific inner ear defects. Homozygous mutant 18.5 days post coitus (dpc) fetuses exhibited smaller cochleae as well as rotational defects of sensory cells and extra cell rows in the inner ear reminiscent of planar cell polarity (PCP) mutants. Cecr2 was expressed in the neuroepithelium, head mesenchyme, and the cochlear floor. Although limited genetic interaction for NTDs was seen with Vangl2, a microarray analysis of PCP genes did not reveal a direct connection to this pathway. The mechanism of Cecr2 action in neurogenesis and inner ear development is likely complex.
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Affiliation(s)
- Christine E Dawe
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
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Kowalik L, Hudspeth AJ. A search for factors specifying tonotopy implicates DNER in hair-cell development in the chick's cochlea. Dev Biol 2011; 354:221-31. [PMID: 21497156 DOI: 10.1016/j.ydbio.2011.03.031] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 03/29/2011] [Accepted: 03/31/2011] [Indexed: 11/16/2022]
Abstract
The accurate perception of sound frequency by vertebrates relies upon the tuning of hair cells, which are arranged along auditory organs according to frequency. This arrangement, which is termed a tonotopic gradient, results from the coordination of many cellular and extracellular features. Seeking the mechanisms that orchestrate those features and govern the tonotopic gradient, we used expression microarrays to identify genes differentially expressed between the high- and low-frequency cochlear regions of the chick (Gallus gallus). Of the three signaling systems that were represented extensively in the results, we focused on the notch pathway and particularly on DNER, a putative notch ligand, and PTPζ, a receptor phosphatase that controls DNER trafficking. Immunohistochemistry confirmed that both proteins are expressed more strongly in hair cells at the cochlear apex than in those at the base. At the apical surface of each hair cell, the proteins display polarized, mutually exclusive localization patterns. Using morpholinos to decrease the expression of DNER or PTPζ as well as a retroviral vector to overexpress DNER, we observed disturbances of hair-bundle morphology and orientation. Our results suggest a role for DNER and PTPζ in hair-cell development and possibly in the specification of tonotopy.
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Affiliation(s)
- Lukasz Kowalik
- Howard Hughes Medical Institute and Laboratory of Sensory Neuroscience, Campus Box 314, The Rockefeller University, 1230 York Avenue, New York, NY 10065-6399, USA
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Tateya T, Imayoshi I, Tateya I, Ito J, Kageyama R. Cooperative functions of Hes/Hey genes in auditory hair cell and supporting cell development. Dev Biol 2011; 352:329-40. [PMID: 21300049 DOI: 10.1016/j.ydbio.2011.01.038] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Revised: 12/16/2010] [Accepted: 01/28/2011] [Indexed: 01/08/2023]
Abstract
Notch-mediated lateral inhibition has been reported to regulate auditory hair cell and supporting cell development from common precursors. While the Notch effector genes Hes1, Hes5 and Hey1 are expressed in the developing cochlea, inactivation of either of them causes only mild abnormality, suggesting their functional redundancy. To explore the roles of Hes/Hey genes in cochlear development, we examined compound heterozygous or homozygous mutant mice that lacked Hes1, Hes5 and Hey1 alleles. We found that a reduction in Hes/Hey gene dosage led to graded increase of hair cell formation. However, if at least one allele of Hes1, Hes5 or Hey1 was intact, excessive hair cells were accompanied by overproduction of supporting cells, suggesting that the hair cell increase does not occur at the expense of supporting cells, and that each Hes/Hey gene functions to induce supporting cells. By contrast, when all alleles of Hes1, Hes5 and Hey1 were inactivated, the number of hair cells increased more drastically, whereas that of supporting cells was unchanged compared with control, suggesting that supporting cell formation was balanced by their overproduction and fate conversion into hair cells. The increase of the cell numbers seemed to occur after the prosensory domain formation in the mutants because the proliferation state and the size of the prosensory domain were not affected. Thus, Hes1, Hes5 and Hey1 cooperatively inhibit hair cell formation, and one allele of Hes1, Hes5 or Hey1 is sufficient for supporting cell production probably by lateral inhibition in the sensory epithelium. Strikingly, Hes/Hey mutations lead to disorganized cell alignment and polarity and to hearing loss despite hair cell overproduction. These results suggest that Hes/Hey gene dosage is essential not only for generation of appropriate numbers of hair cells and supporting cells by controlling cell proliferation and lateral inhibition but also for the hearing ability by regulating the cell alignment and polarity.
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Affiliation(s)
- Tomoko Tateya
- Institute for Virus Research, Kyoto University, Kyoto 606-8507, Japan
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