1
|
O’Donnell J, Zheng J. Vestibular Hair Cells Require CAMSAP3, a Microtubule Minus-End Regulator, for Formation of Normal Kinocilia. Front Cell Neurosci 2022; 16:876805. [PMID: 35783105 PMCID: PMC9247359 DOI: 10.3389/fncel.2022.876805] [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: 02/15/2022] [Accepted: 05/30/2022] [Indexed: 11/29/2022] Open
Abstract
Kinocilia are exceptionally long primary sensory cilia located on vestibular hair cells, which are essential for transmitting key signals that contribute to mammalian balance and overall vestibular system function. Kinocilia have a “9+2” microtubule (MT) configuration with nine doublet MTs surrounding two central singlet MTs. This is uncommon as most mammalian primary sensory cilia have a “9+0” configuration, in which the central MT pair is absent. It has yet to be determined what the function of the central MT pair is in kinocilia. Calmodulin-regulated spectrin-associated protein 3 (CAMSAP3) regulates the minus end of MTs and is essential for forming the central MT pair in motile cilia, which have the “9+2” configuration. To explore the role of the central MT pair in kinocilia, we created a conditional knockout model (cKO), Camsap3-cKO, which intended to eliminate CAMSAP3 in limited organs including the inner ear, olfactory bulb, and kidneys. Immunofluorescent staining of vestibular organs demonstrated that CAMSAP3 proteins were significantly reduced in Camsap3-cKO mice and that aged Camsap3-cKO mice had significantly shorter kinocilia than their wildtype littermates. Transmission electron microscopy showed that aged Camsap3-cKO mice were in fact missing that the central MT pair in kinocilia more often than their wildtype counterparts. In the examination of behavior, wildtype and Camsap3-cKO mice performed equally well on a swim assessment, right-reflex test, and evaluation of balance on a rotarod. However, Camsap3-cKO mice showed slightly altered gaits including reduced maximal rate of change of paw area and a smaller paw area in contact with the surface. Although Camsap3-cKO mice had no differences in olfaction from their wildtype counterparts, Camsap3-cKO mice did have kidney dysfunction that deteriorated their health. Thus, CAMSAP3 is important for establishing and/or maintaining the normal structure of kinocilia and kidney function but is not essential for normal olfaction. Our data supports our hypothesis that CAMSAP3 is critical for construction of the central MT pair in kinocilia, and that the central MT pair may be important for building long and stable axonemes in these kinocilia. Whether shorter kinocilia might lead to abnormal vestibular function and altered gaits in older Camsap3-cKO mice requires further investigation.
Collapse
Affiliation(s)
- Josephine O’Donnell
- Department of Otolaryngology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Jing Zheng
- Department of Otolaryngology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
- Knowles Hearing Center, Northwestern University, Evanston, IL, United States
- *Correspondence: Jing Zheng,
| |
Collapse
|
2
|
Curthoys IS, Grant JW, Pastras CJ, Brown DJ, Burgess AM, Brichta AM, Lim R. A review of mechanical and synaptic processes in otolith transduction of sound and vibration for clinical VEMP testing. J Neurophysiol 2019; 122:259-276. [DOI: 10.1152/jn.00031.2019] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Older studies of mammalian otolith physiology have focused mainly on sustained responses to low-frequency (<50 Hz) or maintained linear acceleration. So the otoliths have been regarded as accelerometers. Thus evidence of otolithic activation and high-precision phase locking to high-frequency sound and vibration appears to be very unusual. However, those results are exactly in accord with a substantial body of knowledge of otolith function in fish and frogs. It is likely that phase locking of otolith afferents to vibration is a general property of all vertebrates. This review examines the literature about the activation and phase locking of single otolithic neurons to air-conducted sound and bone-conducted vibration, in particular the high precision of phase locking shown by mammalian irregular afferents that synapse on striolar type I hair cells by calyx endings. Potassium in the synaptic cleft between the type I hair cell receptor and the calyx afferent ending may be responsible for the tight phase locking of these afferents even at very high discharge rates. Since frogs and fish do not possess full calyx endings, it is unlikely that they show phase locking with such high precision and to such high frequencies as has been found in mammals. The high-frequency responses have been modeled as the otoliths operating in a seismometer mode rather than an accelerometer mode. These high-frequency otolithic responses constitute the neural basis for clinical vestibular-evoked myogenic potential tests of otolith function.
Collapse
Affiliation(s)
- Ian S. Curthoys
- Vestibular Research Laboratory, School of Psychology, the University of Sydney, New South Wales, Australia
| | - J. Wally Grant
- Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, Virginia
| | - Christopher J. Pastras
- The Meniere’s Laboratory, Sydney Medical School, University of Sydney, New South Wales, Australia
| | - Daniel J. Brown
- The Meniere’s Laboratory, Sydney Medical School, University of Sydney, New South Wales, Australia
| | - Ann M. Burgess
- Vestibular Research Laboratory, School of Psychology, the University of Sydney, New South Wales, Australia
| | - Alan M. Brichta
- School of Biomedical Sciences and Pharmacy, The University of Newcastle and Hunter Medical Research Institute. Newcastle, New South Wales, Australia
| | - Rebecca Lim
- School of Biomedical Sciences and Pharmacy, The University of Newcastle and Hunter Medical Research Institute. Newcastle, New South Wales, Australia
| |
Collapse
|
3
|
Nam JH, Grant JW, Rowe MH, Peterson EH. Multiscale modeling of mechanotransduction in the utricle. J Neurophysiol 2019; 122:132-150. [PMID: 30995138 DOI: 10.1152/jn.00068.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
We review recent progress in using numerical models to relate utricular hair bundle and otoconial membrane (OM) structure to the functional requirements imposed by natural behavior in turtles. The head movements section reviews the evolution of experimental attempts to understand vestibular system function with emphasis on turtles, including data showing that accelerations occurring during natural head movements achieve higher magnitudes and frequencies than previously assumed. The structure section reviews quantitative anatomical data documenting topographical variation in the structures underlying macromechanical and micromechanical responses of the turtle utricle to head movement: hair bundles, OM, and bundle-OM coupling. The macromechanics section reviews macromechanical models that incorporate realistic anatomical and mechanical parameters and reveal that the system is significantly underdamped, contrary to previous assumptions. The micromechanics: hair bundle motion and met currents section reviews work based on micromechanical models, which demonstrates that topographical variation in the structure of hair bundles and OM, and their mode of coupling, result in regional specializations for signaling of low frequency (or static) head position and high frequency head accelerations. We conclude that computational models based on empirical data are especially promising for investigating mechanotransduction in this challenging sensorimotor system.
Collapse
Affiliation(s)
- Jong-Hoon Nam
- Department of Mechanical Engineering, Department of Biomedical Engineering, University of Rochester , Rochester, New York
| | - J W Grant
- Department of Biomedical Engineering and Mechanics, Virginia Tech, Blacksburg, Virginia
| | - M H Rowe
- Department of Biology, Neuroscience Program, Quantitative Biology Institute, Ohio University , Athens, Ohio
| | - E H Peterson
- Department of Biology, Neuroscience Program, Quantitative Biology Institute, Ohio University , Athens, Ohio
| |
Collapse
|
4
|
Curthoys I, Burgess AM, Goonetilleke SC. Phase-locking of irregular guinea pig primary vestibular afferents to high frequency (>250 Hz) sound and vibration. Hear Res 2019; 373:59-70. [DOI: 10.1016/j.heares.2018.12.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 12/07/2018] [Accepted: 12/21/2018] [Indexed: 12/28/2022]
|
5
|
Sellon JB, Azadi M, Oftadeh R, Nia HT, Ghaffari R, Grodzinsky AJ, Freeman DM. Nanoscale Poroelasticity of the Tectorial Membrane Determines Hair Bundle Deflections. PHYSICAL REVIEW LETTERS 2019; 122:028101. [PMID: 30720330 PMCID: PMC6813812 DOI: 10.1103/physrevlett.122.028101] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 10/14/2018] [Indexed: 06/09/2023]
Abstract
Stereociliary imprints in the tectorial membrane (TM) have been taken as evidence that outer hair cells are sensitive to shearing displacements of the TM, which plays a key role in shaping cochlear sensitivity and frequency selectivity via resonance and traveling wave mechanisms. However, the TM is highly hydrated (97% water by weight), suggesting that the TM may be flexible even at the level of single hair cells. Here we show that nanoscale oscillatory displacements of microscale spherical probes in contact with the TM are resisted by frequency-dependent forces that are in phase with TM displacement at low and high frequencies, but are in phase with TM velocity at transition frequencies. The phase lead can be as much as a quarter of a cycle, thereby contributing to frequency selectivity and stability of cochlear amplification.
Collapse
Affiliation(s)
- Jonathan B. Sellon
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Mojtaba Azadi
- School of Engineering, College of Science and Engineering, San Francisco State University, San Francisco, CA 94132, USA
- Center for Biomedical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Ramin Oftadeh
- Center for Biomedical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Hadi Tavakoli Nia
- Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Roozbeh Ghaffari
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Alan J. Grodzinsky
- Center for Biomedical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Dennis M. Freeman
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| |
Collapse
|