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Thyroid hormone receptor beta is essential for development of auditory function
1Mount Sinai School of Medicine, Department of Human Genetics, New York, New York 10029, USA.
Nature Genetics
|July 1, 1996
Summary
Thyroid hormone receptor beta (Tr beta) is crucial for auditory development and function. Tr beta-deficient mice show hearing deficits, highlighting its essential role in the auditory system.
Area of Science:
- Endocrinology
- Neuroscience
- Genetics
Background:
- Congenital thyroid disorders are linked to hearing loss, suggesting thyroid hormone's role in auditory development.
- Two thyroid hormone receptor genes, Tr alpha and Tr beta, have overlapping expression patterns during development, making their specific functions unclear.
Purpose of the Study:
- To investigate the specific role of Tr beta in auditory development and function.
- To determine if Tr beta mediates unique or redundant functions compared to Tr alpha.
Main Methods:
- Utilized Tr beta-deficient (Thrb-/-) mice to assess auditory function.
- Measured auditory-evoked brainstem responses (ABR) to evaluate hearing deficits.
- Examined cochlear morphology for developmental abnormalities.
Main Results:
- Tr beta-deficient mice exhibited a permanent, frequency-wide deficit in auditory function.
- Auditory-evoked brainstem responses in mutant mice showed diminished but normal waveforms, indicating a cochlear defect.
- Cochlear development was normal in Tr beta-deficient mice, distinguishing the defect from hypothyroidism-induced malformations.
Conclusions:
- Tr beta is essential for the maturation of auditory function, but not cochlear morphogenesis.
- Tr beta-deficient mice serve as a model for resistance to thyroid hormone (RTH), but recessive mutations have different auditory consequences than dominant RTH mutations.
- Distinct thyroid hormone receptor genes likely serve unique functions in development.