| 2013 |
TMC1 and TMC2 are components of the mechanosensitive ion channel in inner ear hair cells. Cells expressing TMC2 alone showed high calcium permeability and large single-channel currents; cells expressing mutant TMC1 showed reduced calcium permeability and smaller single-channel currents. Cells co-expressing both TMC1 and TMC2 displayed a broad range of single-channel conductances, suggesting heteromeric channel assemblies. TMC2 and TMC1 thus contribute to the permeation properties of the hair cell transduction channel. |
Whole-cell and single-channel patch-clamp recordings from mouse hair cells expressing Tmc1, Tmc2, or mutant Tmc1 (including Tmc1/Tmc2 knockout mice) |
Neuron |
High |
23871232
|
| 2015 |
TMC1 and TMC2 localize to the tips of stereocilia (the site of mechanotransduction) in mature hair cells, and both are absent from the tips of the tallest stereocilia row where MET activity is undetectable. In immature hair cells both proteins distribute along the full stereocilia length. Fluorescent-tagged TMC1-mCherry and TMC2-AcGFP rescued MET currents and hearing in Tmc1Δ/Δ;Tmc2Δ/Δ mice, confirming functionality of the localization data. |
Transgenic knock-in mice expressing TMC1-mCherry and TMC2-AcGFP; transgenic rescue of MET currents; immunofluorescence of endogenous proteins; live-cell imaging |
Cell Reports |
High |
26321635
|
| 2014 |
Tip-link protein PCDH15 physically interacts with TMC1 and TMC2. A membrane-based two-hybrid screen identified interaction between zebrafish Pcdh15a and TMC2a N-terminal fragment; yeast two-hybrid and co-immunoprecipitation confirmed interaction between mouse PCDH15-CD3 isoform and TMC1 or TMC2. Overexpression of the Tmc2a N terminus in zebrafish hair cells mislocalized Pcdh15a within bundles and significantly reduced mechanosensitive responses, demonstrating functional relevance of the complex. |
Membrane-based two-hybrid screen, yeast two-hybrid assay, co-immunoprecipitation (mouse), overexpression of dominant-negative Tmc2a N-terminus in zebrafish with electrophysiological readout |
Proceedings of the National Academy of Sciences of the United States of America |
High |
25114259
|
| 2017 |
Calcium and integrin-binding protein 2 (CIB2) physically binds TMC1 and TMC2, and this interaction is disrupted by deafness-causing CIB2 mutations. Loss of CIB2 abolishes mechanotransduction in auditory hair cells despite intact tip links, establishing CIB2 as required for normal operation of the TMC-containing MET channel complex. |
Co-immunoprecipitation of CIB2 with TMC1/TMC2; characterization of Cib2 knockout and deafness-mutation knock-in mouse lines; electrophysiological recording of MET currents |
Nature Communications |
High |
28663585
|
| 2017 |
TMC2 modifies the pore properties of the MET channel in early postnatal cochlear outer hair cells (OHCs). In Tmc2 knockout OHCs, the channel blocker dihydrostreptomycin (DHS) had higher affinity (both extracellularly and intracellularly), and aminoglycoside entry was reduced during the first postnatal week. These pore-property changes implicate TMC2 as a pore-forming contributor to the neonatal MET channel. |
Whole-cell patch-clamp recordings of MET currents from Tmc2 knockout and heterozygous mice; pharmacological block with dihydrostreptomycin; aminoglycoside uptake assay |
Frontiers in Molecular Neuroscience |
Medium |
29093662
|
| 2019 |
Purified and liposome-reconstituted TMC2 protein (from budgerigar, MuTMC2) possesses intrinsic ion channel activity and responds directly to applied pressure (mechanical stimuli), demonstrating that TMC2 is itself a pore-forming subunit of a mechanosensitive ion channel without requiring additional hair-cell-specific proteins. |
Heterologous expression in insect cells, protein purification, liposome reconstitution, single-channel electrophysiology, pressurized proteoliposome recordings |
Neuron |
High |
31761710
|
| 2024 |
Cryo-EM structure of the native C. elegans TMC-2 complex shows it assembles as a dimer of TMC-2 pore-forming subunits together with the calcium and integrin binding protein CALM-1 and the transmembrane inner ear protein TMIE. Conserved protein-lipid interactions and a π-helical motif in the pore-forming helices are proposed as mechanistically important features. Comparison with the C. elegans TMC-1 complex reveals differences in subunit composition alongside conserved structural features. |
Single-particle cryo-electron microscopy of native TMC-2 complex isolated from C. elegans |
Proceedings of the National Academy of Sciences of the United States of America |
High |
38354260
|
| 2018 |
TMC2 can partially substitute for TMC1 in vestibular hair cells but not in mature cochlear hair cells. Cre-inducible transgenic expression of Tmc2 in Tmc1-null mice restored sensory transduction in vestibular hair cells and transiently in cochlear hair cells, rescuing balance but not auditory function, indicating TMC1 has distinct functional requirements in mature cochlear hair cells not fulfilled by TMC2. |
Cre-inducible Tmc2 knock-in mouse model; electrophysiological recording of hair cell MET currents; auditory brainstem responses; vestibular behavioral assays |
Scientific Reports |
Medium |
30108254
|
| 2018 |
Persistent transgenic Tmc2 expression driven by the Tmc1 promoter in mature cochlear hair cells of Tmc1-null mice only slightly and transiently restored hearing, and outer hair cells eventually lost stereocilia, demonstrating that TMC2 cannot fully substitute for TMC1 in mature cochlear function and that TMC1 has a distinct requirement in this context. |
Transgenic mouse line Tg[PTmc1::Tmc2]; auditory brainstem response and DPOAE hearing tests; electrophysiological recordings; histological analysis of hair cells |
Scientific Reports |
Medium |
30108230
|
| 2025 |
Full-length mouse TMC2, when directed to the plasma membrane via a Fyn lipidation tag (bypassing ER retention), functions as a mechanosensitive ion channel in heterologous cells. TMIE robustly potentiates TMC2 channel activity by modulating gating. Palmitoylation at TMIE residues C76/C77 is required for TMIE stimulation of TMC2 gating. TMC2 + TMIE reconstitute 24 pS single channels with biophysical and pharmacological properties resembling the native MET channel. |
Heterologous expression with Fyn lipidation tag; whole-cell and single-channel patch-clamp electrophysiology; co-expression with TMIE and TMIE mutants (N-terminal deletion, C76A/C77A palmitoylation site mutants) |
Proceedings of the National Academy of Sciences of the United States of America |
High |
39999170
|
| 2025 |
TMC1 and TMC2 function as cholesterol-regulated lipid scramblases in addition to ion channels. Using reconstituted proteoliposomes and molecular dynamics simulations, both proteins facilitate phospholipid translocation across bilayers; activity is tuned by cholesterol and enhanced by deafness-causing TMC1 mutations. In murine auditory hair cells, TMC1-dependent phosphatidylserine externalization and membrane blebbing were observed, linking TMC-dependent membrane homeostasis dysregulation to hair cell pathology. |
Proteoliposome reconstitution scramblase assay, molecular dynamics simulations, phosphatidylserine externalization assay in murine auditory hair cells |
bioRxivpreprint |
Medium |
40631239
|
| 2024 |
TMC2 (and TMC1) function as mechanosensitive scramblases in auditory hair cell stereocilia, with scramblase activity dependent on MET channel opening. Blocking scramblase activity unmasked a second process increasing effective membrane viscosity independently of the MET machinery, revealing dynamic regulation of stereocilia membrane properties. |
BODIPY 1c viscosity sensor, genetic (Tmc2 KO), electrophysiological, and pharmacological approaches in hair cells |
bioRxivpreprint |
Low |
|