title: Connexin26 Mutations Causing Palmoplantar Keratoderma and Deafness Interact with Connexin43, Modifying Gap Junction and Hemichannel Properties.
abstract: Mutations in GJB2 (connexin [Cx]26) cause either deafness or deafness associated with skin diseases. That different disorders can be caused by distinct mutations within the same gene suggests that unique channel activities are influenced by each class of mutation. We have examined the functional characteristics of two human mutations, Cx26-H73R and Cx26-S183F, causing palmoplantar keratoderma (PPK) and deafness. Both failed to form gap junction channels or hemichannels when expressed alone. Coexpression of the mutants with wild-type Cx43 showed a transdominant inhibition of Cx43 gap junction channels, without reductions in Cx43 protein synthesis. In addition, the presence of mutant Cx26 shifted Cx43 channel gating and kinetics toward a more Cx26-like behavior. Coimmunoprecipitation showed Cx43 being pulled down more efficiently with mutant Cx26 than wild-type, confirming the enhanced formation of heteromeric connexons. Finally, the formation of heteromeric connexons resulted in significantly increased Cx43 hemichannel activity in the presence of Cx26 mutants. These findings suggest a common mechanism whereby Cx26 mutations causing PPK and deafness transdominantly influence multiple functions of wild-type Cx43. They also implicate a role for aberrant hemichannel activity in the pathogenesis of PPK and further highlight an emerging role for Cx43 in genetic skin diseases.
authors.affiliation: Department of Physiology and Biophysics, Stony Brook University, Stony Brook, New York, USA; Graduate Program in Genetics, Stony Brook University, Stony Brook, New York, USA.
authors.forename: Zunaira
authors.initials: Z
authors.lastname: Shuja
authors.affiliation: Department of Physiology and Biophysics, Stony Brook University, Stony Brook, New York, USA.
authors.forename: Leping
authors.initials: L
authors.lastname: Li
authors.affiliation: InSTAR Program, Ward Melville High School, Setauket, New York, USA.
authors.forename: Shashank
authors.initials: S
authors.lastname: Gupta
authors.affiliation: Department of Molecular Biology and Genetics, Izmir Institute of Technology, Urla, Izmir, Turkey.
authors.forename: Gülistan
authors.initials: G
authors.lastname: Meşe
authors.affiliation: Department of Physiology and Biophysics, Stony Brook University, Stony Brook, New York, USA. Electronic address: thomas.white@stonybrook.edu.
authors.forename: Thomas W
authors.initials: TW
authors.lastname: White
mesh_terms: D015153:Blotting, Western; D002478:Cells, Cultured; D000072259:Connexin 26; D018031:Connexin 43 / Q000235:genetics; D017630:Connexins / Q000235:genetics*; D003638:Deafness / Q000235:genetics*; D017629:Gap Junctions / Q000235:genetics*; D020022:Genetic Predisposition to Disease; D006801:Humans; D047468:Immunoprecipitation; D007645:Keratoderma, Palmoplantar / Q000235:genetics*; D009154:Mutation; D009865:Oocytes / Q000166:cytology / Q000502:physiology; D012494:Sampling Studies
chemical_list: D018031:Connexin 43; D017630:Connexins; C000607042:GJB2 protein, human; D000072259:Connexin 26