Background: In a search for mutations of μ-crystallin (CRYM), a taxion specific crystalline which is also known as an NADP regulated thyroid hormone binding protein, two mutations were found at the C-terminus in patients with non-syndromic deafness.
Objective: To investigate the mechanism of hearing loss caused by CRYM mutations
Methods: T3 binding activity of mutant μ-crystallin was compared with that of wild-type μ-crystallin, because μ-crystallin is known to be identical to T3 binding protein. To explore the sites within the cochlea where μ-crystallin is functioning, its localisation in the mouse cochlea was investigated immunocytochemically using a specific antibody.
Results: One mutant was shown to have no binding capacity for T3, indicating that CRYM mutations cause auditory dysfunction through thyroid hormone binding properties. Immunocytochemical results indicated that μ-crystallin was distributed within type II fibrocytes of the lateral wall, which are known to contain Na,K-ATPase.
Conclusions:CRYM mutations may cause auditory dysfunction through thyroid hormone binding effects on the fibrocytes of the cochlea. μ-Crystallin may be involved in the potassium ion recycling system together with Na,K-ATPase. Future animal experiments will be necessary to confirm a causal relation between Na,K-ATPase, T3, and deafness.
- 3,5,3′-triiodo-L-thyronine (T3)-binding protein (CTBP)
- spiral ligament
Statistics from Altmetric.com
Conflicts of interest: none declared
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.