The human Cx26-D50A and Cx26-A88V mutations causing keratitis-ichthyosis-deafness syndrome display increased hemichannel activity

Mutations in the human gene encoding connexin 26 (Cx26 or GJB2) cause either nonsyndromic deafness or syndromic deafness associated with skin diseases. That distinct clinical disorders can be caused by different mutations within the same gene suggests that different channel activities influence the...

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Bibliographic Details
Published in:American Journal of Physiology: Cell Physiology 2013-06, Vol.304 (12), p.C1150-C1158
Main Authors: Mhaske, Pallavi V, Levit, Noah A, Li, Leping, Wang, Hong-Zhan, Lee, Jack R, Shuja, Zunaira, Brink, Peter R, White, Thomas W
Format: Article
Language:English
Subjects:
Animals
Cells
Congenital diseases
Connexin 26
Connexins - genetics
Deafness - genetics
Deafness - metabolism
Deafness - pathology
Female
Gene expression
Genes
HeLa Cells
Humans
Ichthyosis - genetics
Ichthyosis - metabolism
Ichthyosis - pathology
Keratinocytes - metabolism
Keratinocytes - pathology
Keratitis - genetics
Keratitis - metabolism
Keratitis - pathology
Mutation
Mutation - genetics
Proteins
Ribonucleic acid
RNA
Xenopus laevis
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Summary:Mutations in the human gene encoding connexin 26 (Cx26 or GJB2) cause either nonsyndromic deafness or syndromic deafness associated with skin diseases. That distinct clinical disorders can be caused by different mutations within the same gene suggests that different channel activities influence the ear and skin. Here we use three different expression systems to examine the functional characteristics of two Cx26 mutations causing either mild (Cx26-D50A) or lethal (Cx26-A88V) keratitis-ichthyosis-deafness (KID) syndrome. In either cRNA-injected Xenopus oocytes, transfected HeLa cells, or transfected primary human keratinocytes, we show that both Cx26-D50A and Cx26-A88V form active hemichannels that significantly increase membrane current flow compared with wild-type Cx26. This increased membrane current accelerated cell death in low extracellular calcium solutions and was not due to increased mutant protein expression. Elevated mutant hemichannel currents could be blocked by increased extracellular calcium concentration. These results show that these two mutations exhibit a shared gain of functional activity and support the hypothesis that increased hemichannel activity is a common feature of human Cx26 mutations responsible for KID syndrome.
ISSN:0363-6143
1522-1563
DOI:10.1152/ajpcell.00374.2012