A short splice form of Xin-actin binding repeat containing 2 (XIRP2) lacking the Xin repeats is required for maintenance of stereocilia morphology and hearing function.
Shimon P FrancisJocelyn F KreyEvan S KrystofiakRunjia CuiSonali NandaWenhao XuBechara KacharPeter G Barr-GillespieJung-Bum ShinPublished in: The Journal of neuroscience : the official journal of the Society for Neuroscience (2015)
Approximately one-third of known deafness genes encode proteins located in the hair bundle, the sensory hair cell's mechanoreceptive organelle. In previous studies, we used mass spectrometry to characterize the hair bundle's proteome, resulting in the discovery of novel bundle proteins. One such protein is Xin-actin binding repeat containing 2 (XIRP2), an actin-cross-linking protein previously reported to be specifically expressed in striated muscle. Because mutations in other actin-cross-linkers result in hearing loss, we investigated the role of XIRP2 in hearing function. In the inner ear, XIRP2 is specifically expressed in hair cells, colocalizing with actin-rich structures in bundles, the underlying cuticular plate, and the circumferential actin belt. Analysis using peptide mass spectrometry revealed that the bundle harbors a previously uncharacterized XIRP2 splice variant, suggesting XIRP2's role in the hair cell differs significantly from that reported in myocytes. To determine the role of XIRP2 in hearing, we applied clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9-mediated genome-editing technology to induce targeted mutations into the mouse Xirp2 gene, resulting in the elimination of XIRP2 protein expression in the inner ear. Functional analysis of hearing in the resulting Xirp2-null mice revealed high-frequency hearing loss, and ultrastructural scanning electron microscopy analyses of hair cells demonstrated stereocilia degeneration in these mice. We thus conclude that XIRP2 is required for long-term maintenance of hair cell stereocilia, and that its dysfunction causes hearing loss in the mouse.
Keyphrases
- hearing loss
- crispr cas
- genome editing
- single cell
- high frequency
- mass spectrometry
- electron microscopy
- cell migration
- induced apoptosis
- high resolution
- cell therapy
- cell cycle arrest
- binding protein
- transcranial magnetic stimulation
- stem cells
- small molecule
- type diabetes
- genome wide
- dna methylation
- mesenchymal stem cells
- high throughput
- dna binding
- cell death
- drug delivery
- transcription factor
- adipose tissue
- amino acid
- case control
- genome wide identification
- ms ms
- insulin resistance