trans-dominant inhibition of connexin-43 by mutant connexin-26: implications for dominant connexin disorders affecting epidermal differentiation
Author:
Rouan Fatima1, White Thomas W.2, Brown Nkecha1, Taylor Aileen M.3, Lucke Thomas W.4, Paul David L.2, Munro Colin S.4, Uitto Jouni1, Hodgins Malcolm B.5, Richard Gabriela1
Affiliation:
1. Department of Dermatology and Cutaneous Biology, and Jefferson Institute of Molecular Medicine, Thomas Jefferson University, Philadelphia, PA, USA 2. Department of Neurobiology, Harvard Medical School, Boston, MA, USA 3. Department of Dermatology, Royal Victoria Infirmary, Newcastle upon Tyne, UK 4. Department of Dermatology, Southern General Hospital, Glasgow, UK 5. Department of Dermatology, University of Glasgow, UK
Abstract
Dominant mutations of GJB2-encoding connexin-26 (Cx26) have pleiotropic effects, causing either hearing impairment (HI) alone or in association with palmoplantar keratoderma (PPK/HI). We examined a British family with the latter phenotype and identified a new dominant GJB2 mutation predicted to eliminate the amino acid residue E42 (ΔE42) in Cx26. To dissect the pathomechanisms that result in diverse phenotypes of dominant GJB2 mutations, we studied the effect of three Cx26 mutants (ΔE42, D66H and R75W) identified in individuals with PPK/HI, and another (W44C) present in individuals with non-syndromic HI on gap junctional intercellular communication. We expressed mutant Cx26 alone and together with the epidermal connexins Cx26, Cx37 and Cx43 in paired Xenopus oocytes, and measured the intercellular coupling by dual voltage clamping. Homotypic expression of each connexin as well as co-expression of wild-type (wt) Cx26/wtCx43 and wtCx26/wtCx37 yielded variable, yet robust, levels of channel activity. However, all four Cx26 mutants were functionally impaired and failed to induce intercellular coupling. When co-expressed with wtCx26, all four mutants suppressed the wtCx26 channel activity consistent with a dominant inhibitory effect. However, only those Cx26 mutants associated with a skin phenotype also significantly (P<0.05) inhibited intercellular conductance of co-expressed wtCx43, indicating a direct interaction of mutant Cx26 units with wtCx43. These results demonstrate, for the first time, a trans-dominant negative effect of Cx26 mutants in vitro. Furthermore, they support a novel concept suggesting that the principal mechanism for manifestation of dominant GJB2 mutations in the skin is their dominant interference with the function of wtCx43. This assumption is further corroborated by our finding that Cx26 and Cx43 focally colocalize at gap junctional plaques in affected skin tissue of two carriers of ΔE42.
Publisher
The Company of Biologists
Reference55 articles.
1. Bergoffen, J., Scherer, S. S. , Wang, S., Scott, M. O., Bone, L. J., Paul, D. L., Chen, K., Lensch, M. W., Chance, P. F. and Fischbeck, K. H. (1993). Connexin mutations in X-linked Charcot-Marie-Tooth disease. Science262, 2039-2042. 2. Beyer, E. C., Gemel, J., Seul, K. H., Larson, D. M., Banach, K. and Brink, P. R. (2000). Modulation of intercellular communication by differential regulation and heteromeric mixing of co-expressed connexins. Braz. J. Med. Biol. Res.33, 391-397. 3. Bruzzone, R., Haefliger, J. A., Gimlich, R. L. and Paul, D. L. (1993). Connexin40, a component of gap junctions in vascular endothelium, is restricted in its ability to interact with other connexins. Mol. Biol. Cell4, 7-20. 4. Bruzzone, R., White, T. W., and Paul, D. L. (1996). Connections with connexins: the molecular basis of direct intercellular signaling. Eur. J. Biochem.238, 1-27. 5. Bukauskas, F. F., Jordan, K., Bukauskiene, A., Bennett, M. V., Lampe, P. D., Laird, D. W. and Verselis, V. K. (2000). Clustering of connexin 43-enhanced green fluorescent protein gap junction channels and functional coupling in living cells. Proc. Natl. Acad. Sci. USA97, 2556-2561.
Cited by
113 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献
|
|