The influence of non-sensory cells on the development of mammalian inner hair cells.

Immature auditory inner hair cells in the mammalian inner ear are capable of firing spontaneous calcium-dependent action potentials, which are required for their maturation into sensory receptors (Johnson et al., 2013; Johnson et al., 2017). Recent studies revealed that non-sensory cells can regulate the frequency and synchroneity of the action potentials among nearby inner hair cells by depolarizing them with ATP released through connexin hemichannels (Tritsch et al., 2007; Tritsch & Bergles, 2010). Nevertheless, the released ATP also induces a secondary potassium release from non-sensory cells, which was reported to depolarize the inner hair cells, thus synchronising their electrical activity (Tritsch et al., 2007; Tritsch & Bergles, 2010; Wang & Bergles, 2015). TMEM16A knockout mice were shown to prevent the potassium release from non-sensory cells and thus reduce the action potential activity in the inner hair cells (Wang & Bergles, 2015). In this study, I used the Cre-induction system to conditionally knockout TMEM16A in the non-sensory cells of the mouse cochlea, which allowed me to study the influence of TMEM16A-mediated potassium release on the action potential activity in the inner hair cells and their maturation. The results indicated that the absence of TMEM16A decreased the frequency and synchroneity of action potentials in immature inner hair cells without changing their spontaneous excitability. However, the influence from TMEM16A might not directly participate in the regulation of the maturing process of the inner hair cells.