Cochlear Outer Hair Cell Motility

Abstract

Normal hearing depends on sound amplification within the mammalian cochlea. The amplification, without which the auditory system is effectively deaf, can be traced to the correct functioning of a group of motile sensory hair cells, the outer hair cells of the cochlea. Acting like motor cells, outer hair cells produce forces that are driven by graded changes in membrane potential. The forces depend on the presence of a motor protein in the lateral membrane of the cells. This protein, known as prestin, is a member of a transporter superfamily SLC26. The functional and structural properties of prestin are described in this review. Whether outer hair cell motility might account for sound amplification at all frequencies is also a critical question and is reviewed here.

Lipid Lateral Mobility in Cochlear Outer Hair Cells: Regional Differences and Regulation by Cholesterol

“…Since the discovery of the outer hair cell (OHC) transmembrane protein prestin, much work has focused on understanding its structure and function (Zheng et al 2000;He et al 2006;Ashmore 2008). Equally important, but less examined, is the role the plasma membrane environment plays in prestin activity and OHC electromotility.…”

La cellule ciliée externe de la cochlée des mammifères

“…Chez l'homme, un dysfonctionnement des CCE, quelle qu'en soit origine (hérédité, traumatisme, médicaments ototoxiques, ou vieillissement, etc. ), entraîne une perte de la sensibilité et de la sélectivité en fréquence de l'organe auditif (pour revues, voir [2][3][4]). Les CCE réagissent mécaniquement à la dépolarisation-repolarisation électri-que induite par la stimulation sonore, par un cycle de contraction-élongation de leur paroi latérale entraînant un changement de leur taille (Figure 2A).…”

Unidirectional Amplification as a Mechanism for Low-Frequency Hearing in Mammals

“…First, hair bundles provide active forces that can enhance their own deflection [7,9,13]. Second, the cell bodies of outer hair cells change their length upon changes in their membrane potential like piezoelectric elements, a phenomenon termed electromotility [1,3,21]. The relative contribution and importance of both processes to cochlear operation remain enigmatic.…”