TMC1 and TMC2 Localize at the Site of Mechanotransduction in Mammalian Inner Ear Hair Cell Stereocilia

Kiyoto Kurima; Seham Ebrahim; Bifeng Pan; Miloslav Sedlacek; Prabuddha Sengupta; Bryan A Millis; Runjia Cui; Hiroshi Nakanishi; Taro Fujikawa; Yoshiyuki Kawashima; Byung Yoon Choi; Kelly Monahan; Jeffrey R Holt; Andrew J Griffith; Bechara Kachar

doi:10.1016/j.celrep.2015.07.058

TMC1 and TMC2 Localize at the Site of Mechanotransduction in Mammalian Inner Ear Hair Cell Stereocilia

Cell Rep. 2015 Sep 8;12(10):1606-17. doi: 10.1016/j.celrep.2015.07.058. Epub 2015 Aug 28.

Authors

Affiliations

¹ Molecular Biology and Genetics Section, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD 20892, USA.
² Laboratory of Cell Structure and Dynamics, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD 20892, USA.
³ Department of Otolaryngology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.
⁴ Cell Biology and Metabolism Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892, USA.
⁵ Molecular Biology and Genetics Section, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD 20892, USA,. Electronic address: griffita@nidcd.nih.gov.
⁶ Laboratory of Cell Structure and Dynamics, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD 20892, USA,. Electronic address: kacharb@nidcd.nih.gov.

Abstract

Mechanosensitive ion channels at stereocilia tips mediate mechanoelectrical transduction (MET) in inner ear sensory hair cells. Transmembrane channel-like 1 and 2 (TMC1 and TMC2) are essential for MET and are hypothesized to be components of the MET complex, but evidence for their predicted spatiotemporal localization in stereocilia is lacking. Here, we determine the stereocilia localization of the TMC proteins in mice expressing TMC1-mCherry and TMC2-AcGFP. Functionality of the tagged proteins was verified by transgenic rescue of MET currents and hearing in Tmc1(Δ/Δ);Tmc2(Δ/Δ) mice. TMC1-mCherry and TMC2-AcGFP localize along the length of immature stereocilia. However, as hair cells develop, the two proteins localize predominantly to stereocilia tips. Both TMCs are absent from the tips of the tallest stereocilia, where MET activity is not detectable. This distribution was confirmed for the endogenous proteins by immunofluorescence. These data are consistent with TMC1 and TMC2 being components of the stereocilia MET channel complex.

Publication types

Research Support, N.I.H., Extramural

MeSH terms

Animals
Cilia / metabolism*
Cilia / ultrastructure
Female
Gene Expression
Hair Cells, Auditory, Inner / physiology*
Hair Cells, Auditory, Inner / ultrastructure
Male
Mechanotransduction, Cellular
Membrane Proteins / genetics
Membrane Proteins / metabolism*
Mice, Transgenic
Protein Transport

Substances

Membrane Proteins
TMC1 protein, mouse
TMC2 protein, mouse

Abstract

Publication types

MeSH terms

Substances

Grants and funding