Stiffness and tension gradients of the hair cell's tip-link complex in the mammalian cochlea

Mélanie Tobin (1) , Atitheb Chaiyasitdhi (1) , Vincent Michel (2) , Nicolas Michalski (2) , Pascal Martin (1)

1 PCC - Laboratoire Physico-Chimie Curie [Institut Curie]
2 Génétique et Physiologie de l'Audition

Sound analysis by the cochlea relies on frequency tuning of mechanosensory hair cells along a tonotopic axis. To clarify the underlying biophysical mechanism, we have investigated the micromechanical properties of the hair cell's mechanoreceptive hair bundle within the apical half of the rat cochlea. We studied both inner and outer hair cells, which send nervous signals to the brain and amplify cochlear vibrations, respectively. We find that tonotopy is associated with gradients of stiffness and resting mechanical tension, with steeper gradients for outer hair cells, emphasizing the division of labor between the two hair-cell types. We demonstrate that tension in the tip links that convey force to the mechano-electrical transduction channels increases at reduced Ca 2+. Finally, we reveal gradients in stiffness and tension at the level of a single tip link. We conclude that mechanical gradients of the tip-link complex may help specify the characteristic frequency of the hair cell.

Mots clés: physics of living systems; rat; tonotopy; cochlea; frequency selectivity; hair bundle; hair cell; hearing; neuroscience

Domaines: Neurobiologie; Biophysique

Mélanie Tobin, Atitheb Chaiyasitdhi, Vincent Michel, Nicolas Michalski, Pascal Martin. Stiffness and tension gradients of the hair cell's tip-link complex in the mammalian cochlea. eLife, 2019, 8, pp.e43473. ⟨10.7554/eLife.43473⟩. ⟨pasteur-02874559⟩