article · 20/05/2014
Transduction channels' gating can control friction on vibrating hair-cell bundles in the ear
Résumé
Hearing starts when sound-evoked mechanical vibrations of the hair-cell bundle activate mechanosensitive ion channels, giving birth to an electrical signal. As for any mechanical system, friction impedes movements of the hair bundle and thus constrains the sensitivity and frequency selectivity of auditory transduction. Friction is generally thought to result mainly from viscous drag by the surrounding fluid. We demonstrate here that the opening and closing of the transduction channels produce internal frictional forces that can dominate viscous drag on the micrometer-sized hair bundle. We characterized friction by analyzing hysteresis in the force-displacement relation of single hair-cell bundles in response to periodic triangular stimuli. For bundle velocities high enough to outrun adaptation, we found that frictional forces were maximal within the narrow region of deflections that elicited significant channel gating, plummeted upon application of a channel blocker, and displayed a sublinear growth for increasing bundle velocity. At low velocity, the slope of the relation between the frictional force and velocity was nearly fivefold larger than the hydrodynamic friction coefficient that was measured when the transduction machinery was decoupled from bundle motion by severing tip links. A theoretical analysis reveals that channel friction arises from coupling the dynamics of the conformational change associated with channel gating to tip-link tension. Varying channel properties affects friction, with faster channels producing smaller friction. We propose that this intrinsic source of friction may contribute to the process that sets the hair cell's characteristic frequency of responsiveness.
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Bormuth, V., Barral, J., Joanny, J.-F., Juelicher, F., & Martin, P. (2014). Transduction channels' gating can control friction on vibrating hair-cell bundles in the ear. Proc. Natl. Acad. Sci. U. S. A., 111(20). https://doi.org/10.1073/pnas.1402556111@article{Bormuth2014_127,
author = {Bormuth, Volker and Barral, Jeremie and Joanny, Jean-Francois and Juelicher, Frank and Martin, Pascal},
year = {2014},
month = {5},
title = {Transduction channels' gating can control friction on vibrating hair-cell bundles in the ear},
journal = {Proc. Natl. Acad. Sci. U. S. A.},
publisher = {NATL ACAD SCIENCES},
volume = {111},
number = {20},
address = {2101 CONSTITUTION AVE NW, WASHINGTON, DC 20418 USA},
abstract = {Hearing starts when sound-evoked mechanical vibrations of the hair-cell bundle activate mechanosensitive ion channels, giving birth to an electrical signal. As for any mechanical system, friction impedes movements of the hair bundle and thus constrains the sensitivity and frequency selectivity of auditory transduction. Friction is generally thought to result mainly from viscous drag by the surrounding fluid. We demonstrate here that the opening and closing of the transduction channels produce internal frictional forces that can dominate viscous drag on the micrometer-sized hair bundle. We characterized friction by analyzing hysteresis in the force-displacement relation of single hair-cell bundles in response to periodic triangular stimuli. For bundle velocities high enough to outrun adaptation, we found that frictional forces were maximal within the narrow region of deflections that elicited significant channel gating, plummeted upon application of a channel blocker, and displayed a sublinear growth for increasing bundle velocity. At low velocity, the slope of the relation between the frictional force and velocity was nearly fivefold larger than the hydrodynamic friction coefficient that was measured when the transduction machinery was decoupled from bundle motion by severing tip links. A theoretical analysis reveals that channel friction arises from coupling the dynamics of the conformational change associated with channel gating to tip-link tension. Varying channel properties affects friction, with faster channels producing smaller friction. We propose that this intrinsic source of friction may contribute to the process that sets the hair cell's characteristic frequency of responsiveness.},
url = {http://www.dx.doi.org/10.1073/pnas.1402556111},
doi = {10.1073/pnas.1402556111},
issn = {0027-8424},
}TY - JOUR
AU - Bormuth, Volker
AU - Barral, Jeremie
AU - Joanny, Jean-Francois
AU - Juelicher, Frank
AU - Martin, Pascal
PY - 2014
DA - 2014/05/20
TI - Transduction channels' gating can control friction on vibrating hair-cell bundles in the ear
JO - Proc. Natl. Acad. Sci. U. S. A.
VL - 111
IS - 20
PB - NATL ACAD SCIENCES
SN - 0027-8424
AB - Hearing starts when sound-evoked mechanical vibrations of the hair-cell bundle activate mechanosensitive ion channels, giving birth to an electrical signal. As for any mechanical system, friction impedes movements of the hair bundle and thus constrains the sensitivity and frequency selectivity of auditory transduction. Friction is generally thought to result mainly from viscous drag by the surrounding fluid. We demonstrate here that the opening and closing of the transduction channels produce internal frictional forces that can dominate viscous drag on the micrometer-sized hair bundle. We characterized friction by analyzing hysteresis in the force-displacement relation of single hair-cell bundles in response to periodic triangular stimuli. For bundle velocities high enough to outrun adaptation, we found that frictional forces were maximal within the narrow region of deflections that elicited significant channel gating, plummeted upon application of a channel blocker, and displayed a sublinear growth for increasing bundle velocity. At low velocity, the slope of the relation between the frictional force and velocity was nearly fivefold larger than the hydrodynamic friction coefficient that was measured when the transduction machinery was decoupled from bundle motion by severing tip links. A theoretical analysis reveals that channel friction arises from coupling the dynamics of the conformational change associated with channel gating to tip-link tension. Varying channel properties affects friction, with faster channels producing smaller friction. We propose that this intrinsic source of friction may contribute to the process that sets the hair cell's characteristic frequency of responsiveness.
DO - 10.1073/pnas.1402556111
UR - http://www.dx.doi.org/10.1073/pnas.1402556111
ER -