HGNC Approved Gene Symbol: TECTB
Cytogenetic location: 10q25.2 Genomic coordinates (GRCh38): 10:112,283,400-112,305,038 (from NCBI)
The genes for alpha-tectorin (602574) and beta-tectorin encode the major noncollagenous proteins of the tectorial membrane of the cochlea.
Legan et al. (1997) cloned mouse alpha- and beta-tectorins. The mouse beta-tectorin gene encodes a 320-amino acid protein containing a hydrophobic secretory signal sequence and 4 potential N-glycosylation sites. Both alpha- and beta-tectorin contain a zona pellucida domain, but otherwise are not homologous.
To identify genes expressed in the vertebrate inner ear, Heller et al. (1998) established an assay that allowed rapid analysis of the differential expression pattern of mRNAs derived from an auditory epithelium-specific cDNA library. They performed subtractive hybridization to create an enriched probe, which was then used to screen the cDNA library. After digoxigenin-labeled antisense cRNAs had been transcribed from hybridization-positive clones, they conducted in situ hybridization on slides bearing cryosections of late embryonic chicken heads, bodies, and cochleae. They found 12 proteins whose mRNAs were specifically or highly expressed in the chicken's inner ear; the remainder encoded proteins that occur more widely. They identified proteins that had previously been described as expressed in the inner ear, such as beta-tectorin, calbindin (CALB1; 114050), and type II collagen (COL2A1; 120140). A second group of proteins abundant in the inner ear included 5 additional types of collagen. A third group, including COCH5B2 (COCH; 603196) and ear-specific connexin, comprised the proteins whose human equivalents are candidates to account for hearing disorders. This last group also included proteins expressed in 2 cells types unique to the inner ear, homogene cells and cells of the tegmentum vasculosum.
Targeted deletion of the mouse alpha-tectorin gene caused loss of cochlear sensitivity (Legan et al., 2000). Knipper et al. (2001) reported that mRNA levels for beta-tectorin, but not alpha-tectorin, were significantly reduced in the cochlear epithelium under constant hypothyroid conditions and that levels of beta-tectorin protein in the tectorial membrane were lower. A delay in the onset of thyroid hormone supply prior to the onset of hearing, described by Knipper et al. (2000) as resulting in permanent hearing defects and loss of active cochlear mechanics, could also lead to permanently reduced beta-tectorin protein levels in the tectorial membrane. After thyroid hormone supply was delayed until postnatal day 8 or later, beta-tectorin protein levels remained low in the tectorial membrane for up to 1 year and were associated with an abnormally structured tectorial membrane and the loss of active cochlear function. The data indicated that a simple delay in thyroid hormone supply during a critical period of development can lead to low beta-tectorin levels in the tectorial membrane and suggested that beta-tectorin may be required for the development of normal hearing.
Heller, S., Sheane, C. A., Javed, Z., Hudspeth, A. J. Molecular markers for cell types of the inner ear and candidate genes for hearing disorders. Proc. Nat. Acad. Sci. 95: 11400-11405, 1998. [PubMed: 9736748] [Full Text: https://doi.org/10.1073/pnas.95.19.11400]
Knipper, M., Richardson, G., Mack, A., Muller, M., Goodyear, R., Limberger, A., Rohbock, K., Kopschall, I., Zenner, H.-P., Zimmermann, U. Thyroid hormone-deficient period prior to the onset of hearing is associated with reduced levels of beta-tectorin protein in the tectorial membrane. J. Biol. Chem. 276: 39046-39052, 2001. [PubMed: 11489885] [Full Text: https://doi.org/10.1074/jbc.M103385200]
Knipper, M., Zinn, C., Maier, H., Praetorius, M., Rohbock, K., Kopschall, I., Zimmermann, U. Thyroid hormone deficiency before the onset of hearing causes irreversible damage to peripheral and central auditory systems. J. Neurophysiol. 83: 3101-3112, 2000. [PubMed: 10805704] [Full Text: https://doi.org/10.1152/jn.2000.83.5.3101]
Legan, P. K., Lukashkina, V. A., Goodyear, R. J., Kossl, M., Russell, I. J., Richardson, G. P. A targeted deletion in alpha-tectorin reveals that the tectorial membrane is required for the gain and timing of cochlear feedback. Neuron 28: 273-285, 2000. [PubMed: 11087000] [Full Text: https://doi.org/10.1016/s0896-6273(00)00102-1]
Legan, P. K., Rau, A., Keen, J. N., Richardson, G. P. The mouse tectorins: modular matrix proteins of the inner ear homologous to components of the sperm-egg adhesion system. J. Biol. Chem. 272: 8791-8801, 1997. [PubMed: 9079715] [Full Text: https://doi.org/10.1074/jbc.272.13.8791]