title: Functional characterization of connexin43 mutations found in patients with oculodentodigital dysplasia.
abstract: Specific mutations in GJA1, the gene encoding the gap junction protein connexin43 (Cx43), cause an autosomal dominant disorder called oculodentodigital dysplasia (ODDD). Here, we characterize the effects of 8 of these mutations on Cx43 function. Immunochemical studies have shown that most of the mutant proteins formed gap junction plaques at the sites of cell-cell apposition. However, 2 of the mutations (a codon duplication in the first extracellular loop, F52dup, and a missense mutation in the second extracellular loop, R202H, produced full-length connexins that failed to properly form gap junction plaques. Cx43 proteins containing ODDD mutations found in the N-terminus (Y17S), first transmembrane domain (G21R, A40V), second transmembrane domain (L90V), and cytoplasmic loop (I130T, K134E) do form gap junction plaques but show compromised channel function. L90V, I130T, and K134E demonstrated a significant decrease in junctional conductance relative to Cx43WT. Mutations Y17S, G21R, and A40V demonstrated a complete lack of functional electrical coupling even in the presence of significant plaque formation between paired cells. Heterologous channels formed by coexpression of Cx43WT and mutation R202H resulted in electrically functional gap junctions that were not permeable to Lucifer yellow. Therefore, the mutations found in ODDD not only cause phenotypic variability, but also result in various functional consequences. Overall, our data show an extensive range of molecular phenotypes, consistent with the pleiotropic nature of the clinical syndrome as a whole.
authors.affiliation: Department of Pharmacology, S.U.N.Y. Upstate Medical University, Syracuse, NY 13210, USA.
authors.forename: Junko
authors.initials: J
authors.lastname: Shibayama
authors.forename: William
authors.initials: W
authors.lastname: Paznekas
authors.forename: Akiko
authors.initials: A
authors.lastname: Seki
authors.forename: Steven
authors.initials: S
authors.lastname: Taffet
authors.forename: Ethylin Wang
authors.initials: EW
authors.lastname: Jabs
authors.forename: Mario
authors.initials: M
authors.lastname: Delmar
authors.forename: Hassan
authors.initials: H
authors.lastname: Musa
mesh_terms: D000015:Abnormalities, Multiple / Q000235:genetics*; D002450:Cell Communication; D018031:Connexin 43 / Q000032:analysis / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D019465:Craniofacial Abnormalities / Q000235:genetics*; D005124:Eye Abnormalities / Q000235:genetics*; D017629:Gap Junctions / Q000502:physiology; D006367:HeLa Cells; D006330:Heart Defects, Congenital / Q000235:genetics*; D006801:Humans; D009154:Mutation; D014071:Tooth Abnormalities / Q000235:genetics*
chemical_list: D018031:Connexin 43