Spontaneous Otoacoustic Emissions in Mice Reflect Changes in Cochlear Amplification and How It Is Controlled by the Tectorial Membrane.

Spontaneous otoacoustic emissions (SOAEs) recorded from the ear canal in the absence of sound reflect cochlear amplification, an outer hair cell (OHC) process required for the extraordinary sensitivity and frequency selectivity of mammalian hearing. Although wild-type mice rarely emit, those with mutations that influence the tectorial membrane (TM) show an incidence of SOAEs similar to that in humans. In this report, we characterized mice with a missense mutation in a gene required for the formation of the striated-sheet matrix within the core of the TM.

Increased Spontaneous Otoacoustic Emissions in Mice with a Detached Tectorial Membrane.

Mutations in genes encoding tectorial membrane (TM) proteins are a significant cause of human hereditary hearing loss (Hildebrand et al. 2011), and several mouse models have been developed to study the functional significance of this accessory structure in the mammalian cochlea. In this study, we use otoacoustic emissions (OAE), signals obtained from the ear canal that provide a measure of cochlear function, to characterize a mouse in which the TM is detached from the spiral limbus due to an absence of otoancorin (Otoa, Lukashkin et al.

Prestin-Dependence of Outer Hair Cell Survival and Partial Rescue of Outer Hair Cell Loss in PrestinV499G/Y501H Knockin Mice.

A knockin (KI) mouse expressing mutated prestinV499G/Y501H (499 prestin) was created to study cochlear amplification. Recordings from isolated outer hair cells (OHC) in this mutant showed vastly reduced electromotility and, as a consequence, reduced hearing sensitivity. Although 499 prestin OHCs were normal in stiffness and longer than OHCs lacking prestin, accelerated OHC death was unexpectedly observed relative to that documented in prestin knockout (KO) mice.

Loss of the tectorial membrane protein CEACAM16 enhances spontaneous, stimulus-frequency, and transiently evoked otoacoustic emissions.

α-Tectorin (TECTA), β-tectorin (TECTB), and carcinoembryonic antigen-related cell adhesion molecule 16 (CEACAM) are secreted glycoproteins that are present in the tectorial membrane (TM), an extracellular structure overlying the hearing organ of the inner ear, the organ of Corti. Previous studies have shown that TECTA and TECTB are both required for formation of the striated-sheet matrix within which collagen fibrils of the TM are imbedded and that CEACAM16 interacts with TECTA. To learn more about the structural and functional significance of CEACAM16, we created a Ceacam16-null mutant mouse.

Functional regulation of the SLC26-family protein prestin by calcium/calmodulin.

The solute carrier gene family 26 (SLC26) encodes membrane proteins with diverse physiological roles but with the common feature of halide involvement. Here, we present bioinformatic and biochemical evidence that SLC26 proteins have intrinsically disordered regions (IDRs) in their C-terminal domains and that these regions contain calmodulin (CaM) binding sites. The veracity of these predictions and the functional consequences of CaM binding were examined in prestin, SLC26A5, as a model for the SLC26 family and as one of the most investigated and best understood members.