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Connexin26 deafness associated mutations show altered permeability to large cationic molecules
Gülistan Meşe1, Virginijus Valiunas, Peter R Brink
1Graduate Program in Genetics, State University of New York, Stony Brook, New York 11794-8661, USA.
American Journal of Physiology. Cell Physiology
|August 8, 2008
Summary
Connexin26 (Cx26) mutations cause hereditary deafness. Mutant Cx26 channels show altered permeability to large molecules, impacting cochlear homeostasis and biochemical coupling.
Area of Science:
- Cellular Biology
- Genetics
- Otolaryngology
Background:
- Intercellular communication via gap junctions is crucial for cochlear homeostasis.
- Mutations in connexin26 (Cx26) are the primary cause of hereditary deafness.
- Gap junction selectivity varies, complicating functional compensation for disease-related mutations.
Purpose of the Study:
- To compare the functional properties of wild-type Cx26 channels with two disease-associated mutants (T8M and N206S).
- To investigate the impact of Cx26 mutations on ionic and molecular permeability.
- To elucidate the role of biochemical coupling in maintaining cochlear homeostasis.
Main Methods:
- Dual whole-cell voltage clamp electrophysiology in transfected cells.
- Dye flux experiments using cAMP, Lucifer Yellow (LY), and ethidium bromide (EtBr).
- Analysis of unitary conductance and tracer permeability.
Main Results:
- Wild-type and mutant Cx26 channels exhibited similar ionic coupling and permeability to K(+) and TEA(+).
- Permeability to cAMP and Lucifer Yellow was comparable between wild-type and mutant channels.
- Mutant Cx26 channels showed significantly reduced transfer of ethidium bromide (EtBr) compared to wild-type.
Conclusions:
- Cx26 mutations alter channel selectivity for larger cationic molecules.
- Reduced permeability to ethidium bromide suggests impaired biochemical coupling in mutant channels.
- Altered Cx26 permeability highlights its essential role in cochlear homeostasis.
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