Tmc1, or transmembrane channel-like protein isoform-1, is a prime candidate for the mechano-electrical transducer (MET) channel in hair cells of the inner ear [1]. It is thought to have a six-transmembrane domain structure and localizes to the tips of the stereocilia in the sensory hair bundle. The function of Tmc1 is crucial for the conversion of mechanical vibrations into electrical signals in the cochlear hair cells, which is fundamental to hearing [3].

In Tmc1 mutant mice, there are significant impacts on auditory function. For example, Tmc1 p.T416K (homologous to a new human deafness mutation) caused deafness and outer hair cell loss by the fourth postnatal week. MET channels in these mutants showed decreased Ca2+ permeability and resting open probability [2]. In Tmc1 p.D569N mutants, by 30 days, mice were profoundly deaf with substantial outer hair cell loss, and MET-channel Ca2+ permeability was reduced, along with reduced expression of the TMC1 D569N channel at the transduction site [5]. In Tmc1;Tmc2 double knockout mice, mechanotransduction currents were lost in hair cells, indicating the involvement of TMC1 in auditory mechanotransduction [3]. LOXHD1 is essential for keeping TMC1-pore forming subunits at the tip link in mouse models, which is important for the function of TMC1-driven mature auditory channels [4].

In conclusion, Tmc1 is essential for the mechano-electrical transduction in cochlear hair cells, playing a key role in the hearing process. Studies using gene knockout mouse models, especially Tmc1 mutants, have revealed its role in maintaining normal auditory function and how its mutations can lead to deafness. Understanding Tmc1 provides insights into the mechanisms of hearing loss and potential therapeutic targets for related diseases.