The precise morphology of the mechanosensitive hair bundle requires seamless integration of actin and microtubule networks. Here, we identify Acf7a as a protein positioned to bridge these distinct cytoskeletal networks in hair cells. By imaging Acf7a-Citrine fusion protein in zebrafish and immunolabeling of vestibular and cochlear mouse hair cells, we show that Acf7a and ACF7 circumscribe, underlie, and are interwoven into the cuticular plate (CP), and they also encircle the basal body of the kinocilium. In cochlear hair cells, ACF7 localization is graded, with the highest concentration near each fonticulus-an area free of F-actin in the region of the cuticular plate that contains the basal body. During hair-cell development and regeneration, Acf7a precedes formation of the hair bundle and CP. Finally, electron tomography demonstrates that the ends of microtubules insert into the CP and are decorated with filamentous linkers connecting microtubules to the CP. These observations are consistent with ACF7 being a linker protein, which may shape the hair cell's cytoskeleton early during hair-bundle genesis. This grant proposal further studies the role of this protien in hair bundle formation.

Public Health Relevance

The hair cell is a mechanoreceptor of the inner ear and lateral line system, which is responsible for hearing, balance, and the detection of water movement by some aquatic vertebrates. We have identified a protein that may govern the formation of this intriguing structure called ACF7. In this grant we aim to understand the role of this protein in hearing.

Agency
National Institute of Health (NIH)
Institute
National Institute on Deafness and Other Communication Disorders (NIDCD)
Type
Research Project (R01)
Project #
5R01DC009437-09
Application #
9520073
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Freeman, Nancy
Project Start
2009-06-05
Project End
2020-06-30
Budget Start
2018-07-01
Budget End
2019-06-30
Support Year
9
Fiscal Year
2018
Total Cost
Indirect Cost
Name
Case Western Reserve University
Department
Otolaryngology
Type
Schools of Medicine
DUNS #
077758407
City
Cleveland
State
OH
Country
United States
Zip Code
44106
Vargo, Jonathon W; Walker, Steven N; Gopal, Suhasini R et al. (2017) Inhibition of Mitochondrial Division Attenuates Cisplatin-Induced Toxicity in the Neuromast Hair Cells. Front Cell Neurosci 11:393
Chou, Shih-Wei; Chen, Zongwei; Zhu, Shaoyuan et al. (2017) A molecular basis for water motion detection by the mechanosensory lateral line of zebrafish. Nat Commun 8:2234
Pollock, Lana M; Chou, Shih-Wei; McDermott Jr, Brian M (2016) My oh my(osin): Insights into how auditory hair cells count, measure, and shape. J Cell Biol 212:135-7
Hwang, Philsang; Chou, Shih-Wei; Chen, Zongwei et al. (2015) The Stereociliary Paracrystal Is a Dynamic Cytoskeletal Scaffold In Vivo. Cell Rep 13:1287-1294
Pollock, Lana M; McDermott Jr, Brian M (2015) The cuticular plate: a riddle, wrapped in a mystery, inside a hair cell. Birth Defects Res C Embryo Today 105:126-39
Gopal, Suhasini R; Chen, Daniel H-C; Chou, Shih-Wei et al. (2015) Zebrafish Models for the Mechanosensory Hair Cell Dysfunction in Usher Syndrome 3 Reveal That Clarin-1 Is an Essential Hair Bundle Protein. J Neurosci 35:10188-201
Antonellis, Patrick J; Pollock, Lana M; Chou, Shih-Wei et al. (2014) ACF7 is a hair-bundle antecedent, positioned to integrate cuticular plate actin and somatic tubulin. J Neurosci 34:305-12
Santos-Cortez, Regie Lyn P; Lee, Kwanghyuk; Azeem, Zahid et al. (2013) Mutations in KARS, encoding lysyl-tRNA synthetase, cause autosomal-recessive nonsyndromic hearing impairment DFNB89. Am J Hum Genet 93:132-40
Chou, Shih-Wei; Hwang, Philsang; Gomez, Gustavo et al. (2011) Fascin 2b is a component of stereocilia that lengthens actin-based protrusions. PLoS One 6:e14807