A fundamental challenge of auditory neuroscience is to understand how hair cells, sensory cells of the inner ear, transduce mechanical displacements with subnanometer resolution and at kilohertz rates. For this purpose, the hair cell deploys its transduction apparatus, an integrated collection of components that includes the transduction channel, tip link, and adaptation motor. To understand mechanical transduction, we must identify molecules that contribute to the transduction apparatus and determine how they interact. One group of related proteins that is essential for hair cells in the myosin family. Three myosin isozymes appear to play specialized roles in hair cells, including: myosin VIIa, mutations in which underlies the human deafness Usher syndrome IB and are responsible for deafness in the shaker-1 mouse; myosin VI, mutations of which are responsible for deafness in the Snell's waltzer mouse; and myosin 1B, which is thought to play a pivotal role in transduction, mediating adaptation to sustained mechanical stimuli. We intend to identify bundle molecules that associate with hair-bundle myosin isozymes and to establish which of these are essential for transduction or adaptation. At least three types of important molecules might bind to the myosin isozyme that mediates adaptation: (i) linker proteins, which could couple myosin molecules to the transduction apparatus; (ii) the extent spring, which restrains the transduction apparatus during large displacements; or (iii) the transduction channel itself. We plan to identify myosin-binding proteins by screening expression libraries; we will then demonstrate the relevance of cloned proteins by delivering to hair cells inhibitory protein fragments, derived from bundle myosin-binding proteins, expecting these fragments will act to block transduction or adaptation. Another set of experiments will test the role of myosins 1B, VI, and VIIa in tip-link regeneration following calcium-chelator treatment. Assembly of the transduction apparatus--which appears to take place during tip-link regeneration--may rely on myosin molecules, and we will test that assertion using biochemical morphological, and electrophysiological experiments. Finally, we will examine myosin motility in hair cells using fluorescence recovery after photobleaching (FRAP). We expect that these dynamics experiments with FRAP will tie together properties of myosin isozymes and their binding proteins, both at steady-state and during tip-link regeneration.

Agency
National Institute of Health (NIH)
Institute
National Institute on Deafness and Other Communication Disorders (NIDCD)
Type
Research Project (R01)
Project #
5R01DC002368-07
Application #
6174943
Study Section
Hearing Research Study Section (HAR)
Program Officer
Donahue, Amy
Project Start
1994-07-01
Project End
2002-06-30
Budget Start
2000-07-01
Budget End
2001-06-30
Support Year
7
Fiscal Year
2000
Total Cost
$281,531
Indirect Cost
Name
Oregon Health and Science University
Department
Otolaryngology
Type
Schools of Medicine
DUNS #
009584210
City
Portland
State
OR
Country
United States
Zip Code
97239
Vranka, Janice A; Staverosky, Julia A; Reddy, Ashok P et al. (2018) Biomechanical Rigidity and Quantitative Proteomics Analysis of Segmental Regions of the Trabecular Meshwork at Physiologic and Elevated Pressures. Invest Ophthalmol Vis Sci 59:246-259
Krey, Jocelyn F; Dumont, Rachel A; Wilmarth, Philip A et al. (2018) ELMOD1 Stimulates ARF6-GTP Hydrolysis to Stabilize Apical Structures in Developing Vestibular Hair Cells. J Neurosci 38:843-857
Rozanov, Dmitri V; Rozanov, Nikita D; Chiotti, Kami E et al. (2018) MHC class I loaded ligands from breast cancer cell lines: A potential HLA-I-typed antigen collection. J Proteomics 176:13-23
Erickson, Timothy; Morgan, Clive P; Olt, Jennifer et al. (2017) Integration of Tmc1/2 into the mechanotransduction complex in zebrafish hair cells is regulated by Transmembrane O-methyltransferase (Tomt). Elife 6:
Krey, J F; Wilmarth, P A; David, L L et al. (2017) Analysis of the Proteome of Hair-Cell Stereocilia by Mass Spectrometry. Methods Enzymol 585:329-354
Kala, Smriti; Mehta, Vaibhav; Yip, Chun Wai et al. (2017) The interaction of a Trypanosoma brucei KH-domain protein with a ribonuclease is implicated in ribosome processing. Mol Biochem Parasitol 211:94-103
Tompkins, Nathan; Spinelli, Kateri J; Choi, Dongseok et al. (2017) A Model for Link Pruning to Establish Correctly Polarized and Oriented Tip Links in Hair Bundles. Biophys J 113:1868-1881
Ren, Tianying; He, Wenxuan; Barr-Gillespie, Peter G (2016) Reverse transduction measured in the living cochlea by low-coherence heterodyne interferometry. Nat Commun 7:10282
Morgan, Clive P; Krey, Jocelyn F; Grati, M'hamed et al. (2016) PDZD7-MYO7A complex identified in enriched stereocilia membranes. Elife 5:
Ebrahim, Seham; Avenarius, Matthew R; Grati, M'hamed et al. (2016) Stereocilia-staircase spacing is influenced by myosin III motors and their cargos espin-1 and espin-like. Nat Commun 7:10833

Showing the most recent 10 out of 62 publications