Protocadherin-15 (Pcdh15) is a component of the tip-links, the extracellular filaments that gate hair cell mechano-electrical transduction channels in the inner ear. There are three Pcdh15 splice isoforms (CD1, CD2 and CD3), which only differ by their cytoplasmic domains; they are thought to function redundantly in mechano-electrical transduction during hair-bundle development, but whether any of these isoforms composes the tip-link in mature hair cells remains unknown. By immunolabelling and both morphological and electrophysiological analyses of post-natal hair cell-specific conditional knockout mice (Pcdh15ex38-fl/ex38-fl Myo15-cre+/-) that lose only this isoform after normal hair-bundle development, we show that Pcdh15-CD2 is an essential component of tip-links in mature auditory hair cells. The finding, in the homozygous or compound heterozygous state, of a PCDH15 frameshift mutation (p.P1515Tfs*4) that affects only Pcdh15-CD2, in profoundly deaf children from two unrelated families, extends this conclusion to humans. These results provide key information for identification of new components of the mature auditory mechano-electrical transduction machinery. This will also serve as a basis for the development of gene therapy for deafness caused by PCDH15 defects.
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http://dx.doi.org/10.15252/emmm.201403976 | DOI Listing |
Vestn Otorinolaringol
December 2024
Pirogov Russian National Research Medical University, Moscow, Russia.
Unlabelled: The acoustic reflex is a physiological protective mechanism of the sound-conducting system of the auditory analyzer, which allows to identify various retrocochlear lesions of the human auditory system. The absence of its registration may indicate both pathology and immaturity of the auditory analyzer in children of the first year of life.
Objective: To register the acoustic reflex in children of the first year of life, to identify a full-fledged acoustic reflex at various frequencies and to analyze the dependence of its appearance on the timing of gestation.
Res Sq
December 2024
Department of Biology, Indiana University, Indianapolis, IN.
In the auditory and vestibular systems, stereocilia are actin-based protrusions that convert mechanical stimuli into electrical signals. During development, stereocilia elongate and widen by adding filamentous actin (F-actin), attaining their mature shape necessary for mechanosensitive function. Myosin motors, including MYO3A/B and MYO15A, are required for normal stereocilia growth, but the regulation of actin and the impact of myosins on actin assembly remain unclear.
View Article and Find Full Text PDFAnimal models provide significant insight into the development of typical and disordered sensory processing. Such models have been established to take advantage of physical and behavioral characteristics of specific species. For example, the Mongolian gerbil is a well-established model for auditory processing, with a hearing range similar in frequency to that of humans and an easily accessible cochlea.
View Article and Find Full Text PDFHum Brain Mapp
December 2024
Otology/Neurotology, Pacific Neuroscience Institute, Los Angeles, California, USA.
Auditory perception is established through experience-dependent stimuli exposure during sensitive developmental periods; however, little is known regarding the structural development of the central auditory pathway in humans. The present study characterized the regional developmental trajectories of the ascending auditory pathway from the brainstem to the auditory cortex from infancy through adolescence using a novel diffusion MRI-based tractography approach and along-tract analyses. We used diffusion tensor imaging (DTI) and neurite orientation dispersion and density imaging (NODDI) to quantify the magnitude and timing of auditory pathway microstructural maturation.
View Article and Find Full Text PDFEur J Transl Myol
December 2024
ENT-Department, Facial-Nerve-Center and Center of Rare Diseases, Jena University Hospital, Jena.
Mega scientific conferences increasingly suffer from the need for short and poster presentations without discussion. An alternative is to organize workshops in hotels large enough to accommodate all participants. This significantly increases the opportunities for constructive discussion during breakfasts, lunches, dinners and long evenings that can bring together experts of scientific and clinical sub-specialties and young fellows.
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