1
|
Na D, Yang Y, Xie L, Piekna-Przybylska D, Bunn D, Shamambo M, White P. Neuroinflammation in a Mouse Model of Alzheimer's Disease versus Auditory Dysfunction: Machine Learning Interpretation and Analysis. RESEARCH SQUARE 2023:rs.3.rs-3370200. [PMID: 37841847 PMCID: PMC10571613 DOI: 10.21203/rs.3.rs-3370200/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2023]
Abstract
Background Auditory dysfunction, including central auditory hyperactivity, hearing loss and hearing in noise deficits, has been reported in 5xFAD Alzheimer's disease (AD) mice, suggesting a causal relationship between amyloidosis and auditory dysfunction. Central auditory hyperactivity correlated in time with small amounts of plaque deposition in the inferior colliculus and medial geniculate body, which are the auditory midbrain and thalamus, respectively. Neuroinflammation has been associated with excitation to inhibition imbalance in the central nervous system, and therefore has been proposed as a link between central auditory hyperactivity and AD in our previous report. However, neuroinflammation in the auditory pathway has not been investigated in mouse amyloidosis models. Methods Machine learning was used to classify the previously obtained auditory brainstem responses (ABRs) from 5xFAD mice and their wild type (WT) littermates. Neuroinflammation was assessed in six auditory-related regions of the cortex, thalamus, and brainstem. Cochlear pathology was assessed in cryosection and whole mount. Behavioral changes were assessed with fear conditioning, open field testing and novel objection recognition. Results Reliable machine learning classification of 5xFAD and WT littermate ABRs were achieved for 6M and 12M, but not 3M. The top features for accurate classification at 6 months of age were characteristics of Waves IV and V. Microglial and astrocytic activation were pronounced in 5xFAD inferior colliculus and medial geniculate body at 6 months, two neural centers that are thought to contribute to these waves. Lower regions of the brainstem were unaffected, and cortical auditory centers also displayed inflammation beginning at 6 months. No losses were seen in numbers of spiral ganglion neurons (SGNs), auditory synapses, or efferent synapses in the cochlea. 5xFAD mice had reduced responses to tones in fear conditioning compared to WT littermates beginning at 6 months. Conclusions Serial use of ABR in early AD patients represents a promising approach for early and inexpensive detection of neuroinflammation in higher auditory brainstem processing centers. As changes in auditory processing are strongly linked to AD progression, central auditory hyperactivity may serve as a biomarker for AD progression and/or stratify AD patients into distinct populations.
Collapse
Affiliation(s)
| | | | - Li Xie
- University of Rochester Medical Center
| | | | | | | | | |
Collapse
|
2
|
Rajan S, Kudryashov DS, Reisler E. Actin Bundles Dynamics and Architecture. Biomolecules 2023; 13:450. [PMID: 36979385 PMCID: PMC10046292 DOI: 10.3390/biom13030450] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Revised: 02/16/2023] [Accepted: 02/20/2023] [Indexed: 03/04/2023] Open
Abstract
Cells use the actin cytoskeleton for many of their functions, including their division, adhesion, mechanosensing, endo- and phagocytosis, migration, and invasion. Actin bundles are the main constituent of actin-rich structures involved in these processes. An ever-increasing number of proteins that crosslink actin into bundles or regulate their morphology is being identified in cells. With recent advances in high-resolution microscopy and imaging techniques, the complex process of bundles formation and the multiple forms of physiological bundles are beginning to be better understood. Here, we review the physiochemical and biological properties of four families of highly conserved and abundant actin-bundling proteins, namely, α-actinin, fimbrin/plastin, fascin, and espin. We describe the similarities and differences between these proteins, their role in the formation of physiological actin bundles, and their properties-both related and unrelated to their bundling abilities. We also review some aspects of the general mechanism of actin bundles formation, which are known from the available information on the activity of the key actin partners involved in this process.
Collapse
Affiliation(s)
- Sudeepa Rajan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
| | - Dmitri S. Kudryashov
- Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH 43210, USA
| | - Emil Reisler
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA
| |
Collapse
|
3
|
Heuermann ML, Matos S, Hamilton D, Cox BC. Regenerated hair cells in the neonatal cochlea are innervated and the majority co-express markers of both inner and outer hair cells. Front Cell Neurosci 2022; 16:841864. [PMID: 36187289 PMCID: PMC9524252 DOI: 10.3389/fncel.2022.841864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 08/29/2022] [Indexed: 11/30/2022] Open
Abstract
After a damaging insult, hair cells can spontaneously regenerate from cochlear supporting cells within the first week of life. While the regenerated cells express several markers of immature hair cells and have stereocilia bundles, their capacity to differentiate into inner or outer hair cells, and ability to form new synaptic connections has not been well-described. In addition, while multiple supporting cell subtypes have been implicated as the source of the regenerated hair cells, it is unclear if certain subtypes have a greater propensity to form one hair cell type over another. To investigate this, we used two CreER mouse models to fate-map either the supporting cells located near the inner hair cells (inner phalangeal and border cells) or outer hair cells (Deiters’, inner pillar, and outer pillar cells) along with immunostaining for markers that specify the two hair cell types. We found that supporting cells fate-mapped by both CreER lines responded early to hair cell damage by expressing Atoh1, and are capable of producing regenerated hair cells that express terminal differentiation markers of both inner and outer hair cells. The majority of regenerated hair cells were innervated by neuronal fibers and contained synapses. Unexpectedly, we also found that the majority of the laterally positioned regenerated hair cells aberrantly expressed both the outer hair cell gene, oncomodulin, and the inner hair cell gene, vesicular glutamate transporter 3 (VGlut3). While this work demonstrates that regenerated cells can express markers of both inner and outer hair cells after damage, VGlut3 expression appears to lack the tight control present during embryogenesis, which leads to its inappropriate expression in regenerated cells.
Collapse
Affiliation(s)
- Mitchell L. Heuermann
- Department of Otolaryngology, Southern Illinois University School of Medicine, Springfield, IL, United States
| | - Sophia Matos
- Department of Otolaryngology, Southern Illinois University School of Medicine, Springfield, IL, United States
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL, United States
| | - Deborah Hamilton
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL, United States
| | - Brandon C. Cox
- Department of Otolaryngology, Southern Illinois University School of Medicine, Springfield, IL, United States
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL, United States
- *Correspondence: Brandon C. Cox,
| |
Collapse
|
4
|
Qi J, Zhang L, Tan F, Liu Y, Chu C, Zhu W, Wang Y, Qi Z, Chai R. Espin distribution as revealed by super-resolution microscopy of stereocilia. Am J Transl Res 2020; 12:130-141. [PMID: 32051742 PMCID: PMC7013225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 12/09/2019] [Indexed: 06/10/2023]
Abstract
Auditory hair cells are the mechanical sensors of sound waves in the inner ear, and the stereocilia, which are actin-rich protrusions of different heights on the apical surfaces of hair cells, are responsible for the transduction of sound waves into electrical signals. As a crucial actin-binding and bundling protein, espin is able to cross-link actin filaments and is therefore necessary for stereocilia morphogenesis. Using advanced super-resolution stimulated emission depletion microscopy, we imaged espin expression at the sub-diffraction limit along the whole length of the stereocilia in outer hair cells and inner hair cells in order to better understand espin's function in the development of stereocilia.
Collapse
Affiliation(s)
- Jieyu Qi
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast UniversityNanjing 210096, China
- iHuman Institute, ShanghaiTech UniversityShanghai, China
- Co-innovation Center of Neuroregeneration, Jiangsu Key Laboratory of Neuroregeneration, Nantong UniversityNantong, China
| | - Liyan Zhang
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast UniversityNanjing 210096, China
- iHuman Institute, ShanghaiTech UniversityShanghai, China
| | - Fangzhi Tan
- iHuman Institute, ShanghaiTech UniversityShanghai, China
| | - Yan Liu
- iHuman Institute, ShanghaiTech UniversityShanghai, China
| | - Cenfeng Chu
- iHuman Institute, ShanghaiTech UniversityShanghai, China
- School of Life Science and Technology, ShanghaiTech UniversityShanghai, China
| | - Weijie Zhu
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast UniversityNanjing 210096, China
| | - Yunfeng Wang
- ENT Institute and Otorhinolaryngology Department of Eye & ENT Hospital, Fudan UniversityShanghai 200031, China
- NHC Key Laboratory of Hearing Medicine (Fudan University)Shanghai 200031, China
| | - Zengxin Qi
- Department of Neurosurgery, Huashan Hospital, Fudan UniversityShanghai 200040, China
| | - Renjie Chai
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast UniversityNanjing 210096, China
- Co-innovation Center of Neuroregeneration, Jiangsu Key Laboratory of Neuroregeneration, Nantong UniversityNantong, China
- Institute for Stem Cell and Regeneration, Chinese Academy of ScienceBeijing, China
- Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast UniversityNanjing 211189, China
- Beijing Key Laboratory of Neural Regeneration and Repair, Capital Medical UniversityBeijing 100069, China
| |
Collapse
|
5
|
Lang H, Nishimoto E, Xing Y, Brown LN, Noble KV, Barth JL, LaRue AC, Ando K, Schulte BA. Contributions of Mouse and Human Hematopoietic Cells to Remodeling of the Adult Auditory Nerve After Neuron Loss. Mol Ther 2016; 24:2000-2011. [PMID: 27600399 PMCID: PMC5154482 DOI: 10.1038/mt.2016.174] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 08/25/2016] [Indexed: 12/20/2022] Open
Abstract
The peripheral auditory nerve (AN) carries sound information from sensory hair cells to the brain. The present study investigated the contribution of mouse and human hematopoietic stem cells (HSCs) to cellular diversity in the AN following the destruction of neuron cell bodies, also known as spiral ganglion neurons (SGNs). Exposure of the adult mouse cochlea to ouabain selectively killed type I SGNs and disrupted the blood-labyrinth barrier. This procedure also resulted in the upregulation of genes associated with hematopoietic cell homing and differentiation, and provided an environment conducive to the tissue engraftment of circulating stem/progenitor cells into the AN. Experiments were performed using both a mouse-mouse bone marrow transplantation model and a severely immune-incompetent mouse model transplanted with human CD34+ cord blood cells. Quantitative immunohistochemical analysis of recipient mice demonstrated that ouabain injury promoted an increase in the number of both HSC-derived macrophages and HSC-derived nonmacrophages in the AN. Although rare, a few HSC-derived cells in the injured AN exhibited glial-like qualities. These results suggest that human hematopoietic cells participate in remodeling of the AN after neuron cell body loss and that hematopoietic cells can be an important resource for promoting AN repair/regeneration in the adult inner ear.
Collapse
Affiliation(s)
- Hainan Lang
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, USA.
| | - Eishi Nishimoto
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Yazhi Xing
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| | - LaShardai N Brown
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Kenyaria V Noble
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Jeremy L Barth
- Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Amanda C LaRue
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, USA; Research Services, Ralph H. Johnson Department of Veterans Affairs Medical Center, Charleston, South Carolina, USA
| | - Kiyoshi Ando
- Research Center for Regenerative Medicine, Division of Hematopoiesis, Tokai University School of Medicine, Tokyo, Japan
| | - Bradley A Schulte
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, USA
| |
Collapse
|
6
|
Zheng L, Beeler DM, Bartles JR. Characterization and regulation of an additional actin-filament-binding site in large isoforms of the stereocilia actin-bundling protein espin. J Cell Sci 2014; 127:1306-17. [PMID: 24424026 PMCID: PMC3953818 DOI: 10.1242/jcs.143255] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The espin actin-bundling proteins, which are produced as isoforms of different sizes from a single gene, are required for the growth of hair cell stereocilia. We have characterized an additional actin-filament-binding site present in the extended amino-termini of large espin isoforms. Constitutively active in espin 2, the site increased the size of actin bundles formed in vitro and inhibited actin fluorescence recovery in microvilli. In espin 1, which has an N-terminal ankyrin repeat domain, the site was autoinhibited by binding between the ankyrin repeat domain and a peptide near the actin-binding site. Deletion of this peptide from espin 1 activated its actin-binding site. The peptide resembled tail homology domain I of myosin III, a ligand of the ankyrin repeat domain localized with espin 1 at the tip of stereocilia. A myosin III tail homology domain I peptide, but not scrambled control peptides, inhibited internal binding of the ankyrin repeat domain and released the espin 1 actin-binding site from autoinhibition. Thus, this regulation could result in local activation of the additional actin-binding site of espin 1 by myosin III in stereocilia.
Collapse
Affiliation(s)
- Lili Zheng
- Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611 USA
| | | | | |
Collapse
|
7
|
Guthrie OW. Genetic/transgenic conditional expression of full-length and headless nonmuscle myosin-II molecules: head domain regulates localization in auditory neurons. Int J Pediatr Otorhinolaryngol 2013; 77:785-91. [PMID: 23499291 DOI: 10.1016/j.ijporl.2013.02.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Revised: 02/10/2013] [Accepted: 02/12/2013] [Indexed: 11/29/2022]
Abstract
OBJECTIVE Human genetic mutations that affect the N-terminal head-domain of the nonmuscle myosin-II (MyoII) molecule can result in nonsyndromic sensorineural hearing loss but the underlying mechanism is unknown. Ultimately, MyoII must be appropriately localized in order to execute endogenous functions. The aim of the current study is to determine whether the head-domain of MyoII regulates in vivo localization of the molecule in living and fixed preparations of the auditory organ. METHODS A genetic/transgenic GAL4-UAS approach was used to selectively drive the expression of zip/MyoII (Drosophila homologue of human nonmuscle MyoII) in Drosophila melanogaster auditory (Johnston's organ) sensory neurons. To follow the distribution of the full-length transgene encoded by MyoII, the N-terminus was fused to green fluorescent protein. Additionally, headless zip/MyoII molecules with and without isoleucine-glutamine or IQ motifs were also expressed in Johnston's organ neurons. RESULTS Removing the entire head domain of MyoII induced localization in neuronal dendrites while removing only a portion of the head but keeping the IQ motif induced localization in the soma and axons of the neurons. CONCLUSIONS The findings suggest that the head domain regulates in vivo localization of MyoII in auditory neurons.
Collapse
Affiliation(s)
- O'neil W Guthrie
- Loma Linda Veterans Hospital, Research Service-151, Loma Linda, CA 92357, USA. O'
| |
Collapse
|
8
|
Xing Y, Samuvel DJ, Stevens SM, Dubno JR, Schulte BA, Lang H. Age-related changes of myelin basic protein in mouse and human auditory nerve. PLoS One 2012; 7:e34500. [PMID: 22496821 PMCID: PMC3320625 DOI: 10.1371/journal.pone.0034500] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Accepted: 03/06/2012] [Indexed: 11/19/2022] Open
Abstract
Age-related hearing loss (presbyacusis) is the most common type of hearing impairment. One of the most consistent pathological changes seen in presbyacusis is the loss of spiral ganglion neurons (SGNs). Defining the cellular and molecular basis of SGN degeneration in the human inner ear is critical to gaining a better understanding of the pathophysiology of presbyacusis. However, information on age-related cellular and molecular alterations in the human spiral ganglion remains scant, owing to the very limited availably of human specimens suitable for high resolution morphological and molecular analysis. This study aimed at defining age-related alterations in the auditory nerve in human temporal bones and determining if immunostaining for myelin basic protein (MBP) can be used as an alternative approach to electron microscopy for evaluating myelin degeneration. For comparative purposes, we evaluated ultrastructural alternations and changes in MBP immunostaining in aging CBA/CaJ mice. We then examined 13 temporal bones from 10 human donors, including 4 adults aged 38-46 years (middle-aged group) and 6 adults aged 63-91 years (older group). Similar to the mouse, intense immunostaining of MBP was present throughout the auditory nerve of the middle-aged human donors. Significant declines in MBP immunoreactivity and losses of MBP(+) auditory nerve fibers were observed in the spiral ganglia of both the older human and aged mouse ears. This study demonstrates that immunostaining for MBP in combination with confocal microscopy provides a sensitive, reliable, and efficient method for assessing alterations of myelin sheaths in the auditory nerve. The results also suggest that myelin degeneration may play a critical role in the SGN loss and the subsequent decline of the auditory nerve function in presbyacusis.
Collapse
Affiliation(s)
- Yazhi Xing
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Devadoss J. Samuvel
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Shawn M. Stevens
- Department of Otolaryngology – Head & Neck Surgery, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Judy R. Dubno
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, United States of America
- Department of Otolaryngology – Head & Neck Surgery, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Bradley A. Schulte
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, United States of America
- Department of Otolaryngology – Head & Neck Surgery, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Hainan Lang
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina, United States of America
- * E-mail:
| |
Collapse
|
9
|
Wang L, Zou J, Shen Z, Song E, Yang J. Whirlin interacts with espin and modulates its actin-regulatory function: an insight into the mechanism of Usher syndrome type II. Hum Mol Genet 2011; 21:692-710. [PMID: 22048959 DOI: 10.1093/hmg/ddr503] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Whirlin mutations cause retinal degeneration and hearing loss in Usher syndrome type II (USH2) and non-syndromic deafness, DFNB31. Its protein recruits other USH2 causative proteins to form a complex at the periciliary membrane complex in photoreceptors and the ankle link of the stereocilia in hair cells. However, the biological function of this USH2 protein complex is largely unknown. Using a yeast two-hybrid screen, we identified espin, an actin-binding/bundling protein involved in human deafness when defective, as a whirlin-interacting protein. The interaction between these two proteins was confirmed by their coimmunoprecipitation and colocalization in cultured cells. This interaction involves multiple domains of both proteins and only occurs when espin does not bind to actin. Espin was partially colocalized with whirlin in the retina and the inner ear. In whirlin knockout mice, espin expression changed significantly in these two tissues. Further studies found that whirlin increased the mobility of espin and actin at the actin bundles cross-linked by espin and, eventually, affected the dimension of these actin bundles. In whirlin knockout mice, the stereocilia were thickened in inner hair cells. We conclude that the interaction between whirlin and espin and the balance between their expressions are required to maintain the actin bundle network in photoreceptors and hair cells. Disruption of this actin bundle network contributes to the pathogenic mechanism of hearing loss and retinal degeneration caused by whirlin and espin mutations. Espin is a component of the USH2 protein complex and could be a candidate gene for Usher syndrome.
Collapse
Affiliation(s)
- Le Wang
- Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah, Salt Lake City, UT 84132, USA
| | | | | | | | | |
Collapse
|
10
|
Ida-Eto M, Oyabu A, Ohkawara T, Tashiro Y, Narita N, Narita M. Existence of manserin, a secretogranin II-derived neuropeptide, in the rat inner ear: relevance to modulation of auditory and vestibular system. J Histochem Cytochem 2011; 60:69-75. [PMID: 22034517 DOI: 10.1369/0022155411425688] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Manserin is a 40-amino acid neuropeptide derived from rat brain. Manserin has been shown to distribute in the neuroendocrine system, such as the pituitary and adrenal glands, but it has been little studied in other organs. In this study, the authors examined localization of manserin in the inner ear of the adult Wistar rat using immunohistochemical analyses. Manserin immunoreactivity was detected in the neuronal terminals of the organ of Corti and type II spiral ganglion cells. In addition to being identified in the auditory system, manserin was detected at the synapses of the vestibular system, such as saccule, utricle, and semicircular canal. These results suggest that inner ear manserin may be involved in the function of peripheral auditory and vestibular systems.
Collapse
Affiliation(s)
- Michiru Ida-Eto
- Department of Anatomy II, Mie University, Graduate School of Medicine, Mie, Japan.
| | | | | | | | | | | |
Collapse
|
11
|
Castiglioni AJ, Remis NN, Flores EN, García-Añoveros J. Expression and vesicular localization of mouse Trpml3 in stria vascularis, hair cells, and vomeronasal and olfactory receptor neurons. J Comp Neurol 2011; 519:1095-1114. [PMID: 21344404 PMCID: PMC4105223 DOI: 10.1002/cne.22554] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
TRPML3 is a member of the mucolipin branch of the transient receptor potential cation channel family. A dominant missense mutation in Trpml3 (also known as Mcoln3) causes deafness and vestibular impairment characterized by stereocilia disorganization, hair cell loss, and endocochlear potential reduction. Both marginal cells of the stria vascularis and hair cells express Trpml3 mRNA. Here we used in situ hybridization, quantitative RT-qPCR, and immunohistochemistry with several antisera raised against TRPML3 to determine the expression and subcellular distribution of TRPML3 in the inner ear as well as in other sensory organs. We also use Trpml3 knockout tissues to distinguish TRPML3-specific from nonspecific immunoreactivities. We find that TRPML3 localizes to vesicles of hair cells and strial marginal cells but not to stereociliary ankle links or pillar cells, which nonspecifically react with two antisera raised against TRPML3. Upon cochlear maturation, TRPML3 protein is redistributed to perinuclear vesicles of strial marginal cells and is augmented in inner hair cells vs. outer hair cells. Mouse somatosensory neurons, retinal neurons, and taste receptor cells do not appear to express physiologically relevant levels of TRPML3. Finally, we found that vomeronasal and olfactory sensory receptor cells do express TRPML3 mRNA and protein, which localizes to vesicles in their somas and dendrites as well as at apical dendritic knobs.
Collapse
Affiliation(s)
- Andrew J. Castiglioni
- Department of Anesthesiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611
| | - Natalie N. Remis
- Department of Anesthesiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611
- Integrated Graduate Program in the Life Sciences (IGP), Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611
| | - Emma N. Flores
- Department of Anesthesiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611
- Northwestern University Interdepartmental Neuroscience (NUIN) Graduate Program, Chicago, Illinois 60611
| | - Jaime García-Añoveros
- Department of Anesthesiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611
- Integrated Graduate Program in the Life Sciences (IGP), Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611
- Northwestern University Interdepartmental Neuroscience (NUIN) Graduate Program, Chicago, Illinois 60611
- Departments of Neurology and Physiology, and Hugh Knowles Center for Clinical and Basic Science in Hearing and Its Disorders, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611
| |
Collapse
|
12
|
Sekerková G, Richter CP, Bartles JR. Roles of the espin actin-bundling proteins in the morphogenesis and stabilization of hair cell stereocilia revealed in CBA/CaJ congenic jerker mice. PLoS Genet 2011; 7:e1002032. [PMID: 21455486 PMCID: PMC3063760 DOI: 10.1371/journal.pgen.1002032] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2010] [Accepted: 02/02/2011] [Indexed: 01/19/2023] Open
Abstract
Hearing and vestibular function depend on mechanosensory staircase collections of hair cell stereocilia, which are produced from microvillus-like precursors as their parallel actin bundle scaffolds increase in diameter and elongate or shorten. Hair cell stereocilia contain multiple classes of actin-bundling protein, but little is known about what each class contributes. To investigate the roles of the espin class of actin-bundling protein, we used a genetic approach that benefited from a judicious selection of mouse background strain and an examination of the effects of heterozygosity. A congenic jerker mouse line was prepared by repeated backcrossing into the inbred CBA/CaJ strain, which is known for excellent hearing and minimal age-related hearing loss. We compared stereocilia in wild-type CBA/CaJ mice, jerker homozygotes that lack espin proteins owing to a frameshift mutation in the espin gene, and jerker heterozygotes that contain reduced espin levels. The lack of espins radically impaired stereociliary morphogenesis, resulting in stereocilia that were abnormally thin and short, with reduced differential elongation to form a staircase. Mean stereociliary diameter did not increase beyond ∼0.10–0.14 µm, making stereocilia ∼30%–60% thinner than wild type and suggesting that they contained ∼50%–85% fewer actin filaments. These characteristics indicate a requirement for espins in the appositional growth and differential elongation of the stereociliary parallel actin bundle and fit the known biological activities of espins in vitro and in transfected cells. The stereocilia of jerker heterozygotes showed a transient proximal-distal tapering suggestive of haploinsufficiency and a slowing of morphogenesis that revealed previously unrecognized assembly steps and intermediates. The lack of espins also led to a region-dependent degeneration of stereocilia involving shortening and collapse. We conclude that the espin actin-bundling proteins are required for the assembly and stabilization of the stereociliary parallel actin bundle. Stereocilia are the fingerlike projections of inner ear hair cells that detect sound and motion. Stereocilia grow to specific lengths and diameters and form staircase-like arrays. The changes in size appear to be driven by matching alterations in the dimensions of an underlying molecular scaffold consisting of a bundle of actin filaments cross-linked by actin-bundling proteins. To elucidate the roles of the espin actin-bundling proteins in hair cell stereocilia, we carry out an in-depth accounting of stereociliary size and shape in the jerker mutant mouse, which lacks the espin proteins because of a mutation in the espin gene. We examine a new and improved jerker mouse with a genetic background known for high-quality lifelong hearing. We find that, in the absence of espins, stereocilia do not increase in diameter or complete their elongation, but instead bend, shorten, and disappear. Although the specifics vary according to inner ear region, the stereociliary defects are profound and can readily account for the deafness and balance problems of jerker mice and humans with certain espin gene mutations. Even reducing espin levels by one-half leads to temporary defects in stereociliary diameter. Thus, espins play crucial roles in the formation and maintenance of hair cell stereocilia.
Collapse
Affiliation(s)
- Gabriella Sekerková
- Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - Claus-Peter Richter
- Department of Otolaryngology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- Hugh Knowles Center for Clinical and Basic Science in Hearing and Its Disorders, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
| | - James R. Bartles
- Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- Hugh Knowles Center for Clinical and Basic Science in Hearing and Its Disorders, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America
- * E-mail:
| |
Collapse
|
13
|
Jyothi V, Li M, Kilpatrick LA, Smythe N, LaRue AC, Zhou D, Schulte BA, Schmiedt RA, Lang H. Unmyelinated auditory type I spiral ganglion neurons in congenic Ly5.1 mice. J Comp Neurol 2010; 518:3254-71. [PMID: 20575058 DOI: 10.1002/cne.22398] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
With the exception of humans, the somata of type I spiral ganglion neurons (SGNs) of most mammalian species are heavily myelinated. In an earlier study, we used Ly5.1 congenic mice as transplant recipients to investigate the role of hematopoietic stem cells in the adult mouse inner ear. An unanticipated finding was that a large percentage of the SGNs in this strain were unmyelinated. Further characterization of the auditory phenotype of young adult Ly5.1 mice in the present study revealed several unusual characteristics, including 1) large aggregates of unmyelinated SGNs in the apical and middle turns, 2) symmetrical junction-like contacts between the unmyelinated neurons, 3) abnormal expression patterns for CNPase and connexin 29 in the SGN clusters, 4) reduced SGN density in the basal cochlea without a corresponding loss of sensory hair cells, 5) significantly delayed auditory brainstem response (ABR) wave I latencies at low and middle frequencies compared with control mice with similar ABR threshold, and 6) elevated ABR thresholds and deceased wave I amplitudes at high frequencies. Taken together, these data suggest a defect in Schwann cells that leads to incomplete myelinization of SGNs during cochlear development. The Ly5.1 mouse strain appears to be the only rodent model so far identified with a high degree of the "human-like" feature of unmyelinated SGNs that aggregate into neural clusters. Thus, this strain may provide a suitable animal platform for modeling human auditory information processing such as synchronous neural activity and other auditory response properties.
Collapse
Affiliation(s)
- Vinu Jyothi
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, South Carolina 29425, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Jahan I, Pan N, Kersigo J, Fritzsch B. Neurod1 suppresses hair cell differentiation in ear ganglia and regulates hair cell subtype development in the cochlea. PLoS One 2010; 5:e11661. [PMID: 20661473 PMCID: PMC2908541 DOI: 10.1371/journal.pone.0011661] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2010] [Accepted: 06/23/2010] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND At least five bHLH genes regulate cell fate determination and differentiation of sensory neurons, hair cells and supporting cells in the mammalian inner ear. Cross-regulation of Atoh1 and Neurog1 results in hair cell changes in Neurog1 null mice although the nature and mechanism of the cross-regulation has not yet been determined. Neurod1, regulated by both Neurog1 and Atoh1, could be the mediator of this cross-regulation. METHODOLOGY/PRINCIPAL FINDINGS We used Tg(Pax2-Cre) to conditionally delete Neurod1 in the inner ear. Our data demonstrate for the first time that the absence of Neurod1 results in formation of hair cells within the inner ear sensory ganglia. Three cell types, neural crest derived Schwann cells and mesenchyme derived fibroblasts (neither expresses Neurod1) and inner ear derived neurons (which express Neurod1) constitute inner ear ganglia. The most parsimonious explanation is that Neurod1 suppresses the alternative fate of sensory neurons to develop as hair cells. In the absence of Neurod1, Atoh1 is expressed and differentiates cells within the ganglion into hair cells. We followed up on this effect in ganglia by demonstrating that Neurod1 also regulates differentiation of subtypes of hair cells in the organ of Corti. We show that in Neurod1 conditional null mice there is a premature expression of several genes in the apex of the developing cochlea and outer hair cells are transformed into inner hair cells. CONCLUSIONS/SIGNIFICANCE Our data suggest that the long noted cross-regulation of Atoh1 expression by Neurog1 might actually be mediated in large part by Neurod1. We suggest that Neurod1 is regulated by both Neurog1 and Atoh1 and provides a negative feedback for either gene. Through this and other feedback, Neurod1 suppresses alternate fates of neurons to differentiate as hair cells and regulates hair cell subtypes.
Collapse
Affiliation(s)
- Israt Jahan
- Department of Biology, University of Iowa, Iowa City, Iowa, United States of America
| | - Ning Pan
- Department of Biology, University of Iowa, Iowa City, Iowa, United States of America
| | - Jennifer Kersigo
- Department of Biology, University of Iowa, Iowa City, Iowa, United States of America
| | - Bernd Fritzsch
- Department of Biology, University of Iowa, Iowa City, Iowa, United States of America
| |
Collapse
|
15
|
Abnormal circling behavior in rat mutants and its relevance to model specific brain dysfunctions. Neurosci Biobehav Rev 2010; 34:31-49. [DOI: 10.1016/j.neubiorev.2009.07.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2009] [Accepted: 07/06/2009] [Indexed: 12/16/2022]
|
16
|
Current world literature. Curr Opin Otolaryngol Head Neck Surg 2009; 17:412-8. [PMID: 19755872 DOI: 10.1097/moo.0b013e3283318f24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
17
|
Cao XJ, McGinley MJ, Oertel D. Connections and synaptic function in the posteroventral cochlear nucleus of deaf jerker mice. J Comp Neurol 2008; 510:297-308. [PMID: 18634002 DOI: 10.1002/cne.21788] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Mutations in the gene that encodes espins can cause deafness and vestibular disorders; mice that are homozygous for the autosomal recessive jerker mutation in the espin gene never hear. Extracellular injections of biocytin into the anteroventral cochlear nucleus (AVCN) revealed that although the cochlear nuclei are smaller in je/je mice, the topography in its innervation resembles that in wild-type mice. Auditory nerve fibers innervate narrow, topographically organized, "isofrequency" bands in deaf animals over the ages examined, P18-P70. The projection of tuberculoventral cells was topographic in je/je as in wild-type mice. Terminals of auditory nerve fibers in the multipolar cell area included both large and small endings, whereas in the octopus cell area they were exclusively small boutons in je/je as in wild-type mice, but end bulbs near the nerve root of je/je animals were smaller than in hearing animals. In whole-cell recordings from targets of auditory nerve fibers, octopus and T stellate cells, miniature excitatory postsynaptic currents (mEPSCs) had similar shapes as in +/+, indicating that the properties of AMPA receptors were not affected by the mutation. In je/je animals the frequency of spontaneous mEPSCs was elevated, and synaptic depression in responses to trains of shocks delivered at between 100 and 333 Hz was greater than in wild-type mice, indicating that the probability of neurotransmitter release was increased. The frequency of spontaneous mEPSCs and extent of synaptic depression were greater in octopus than in T stellate cells, in both wild-type and in je/je mice.
Collapse
Affiliation(s)
- Xiao-Jie Cao
- Department of Physiology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706, USA
| | | | | |
Collapse
|