A Prestin Motor in Chicken Auditory Hair Cells: Active Force Generation in a Nonmammalian Species

Active force generation by outer hair cells (OHCs) underlies amplification and frequency tuning in the mammalian cochlea but whether such a process exists in nonmammals is unclear. Here, we demonstrate that hair cells of the chicken auditory papilla possess an electromechanical force generator in addition to active hair bundle motion due to mechanotransducer channel gating. The properties of the force generator, its voltage dependence and susceptibility to salicylate, as well as an associated chloride-sensitive nonlinear capacitance, suggest involvement of the chicken homolog of prestin, the OHC motor protein. The presence of chicken prestin in the hair cell lateral membrane was confirmed by immunolabeling studies. The hair bundle and prestin motors together create sufficient force to produce fast lateral displacements of the tectorial membrane. Our results imply that the first use of prestin as a motor protein occurred early in amniote evolution and was not a mammalian invention as is usually supposed. •Chicken auditory hair cells have two force generators for amplification and tuning•One is due to transducer channel gating, the other to chicken homolog of prestin•Both evoke negative hair bundle forces tightly coupled to tectorial membrane motion•Results argue that prestin first used as a motor protein early in amniote evolution The high sensitivity of mammalian hearing relies on outer hair cell electromotility underscored by the membrane protein prestin. While generally thought to be unique to mammals, Beurg et al. now demonstrate a prestin motor in avian hair cells, implying the mechanism originated in early amniotes.