CRYM mutations cause deafness through thyroid hormone binding properties in the fibrocytes of the cochlea. Issue 6 (1st June 2006)

• Record Type: Journal Article
• Authors: Oshima, A; Suzuki, S; Takumi, Y; Hashizume, K; Abe, S; Usami, S
• Is Part Of: Journal of medical genetics. Volume 43:Issue 6(2006)
• Page Start: e25
• Page End: e25
• Publication Date: 2006-06-01
• Subjects: μ-crystallin -- Na -- K-ATPase -- 3, 5, 3′-triiodo-L-thyronine (T3)-binding protein (CTBP) -- spiral ligament -- deafness; Medical genetics -- Periodicals; 616.042
• DOI: 10.1136/jmg.2005.034397
• Languages: English
• ISSNs: 1468-6244

Abstract

Abstract : 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.