Funding sources This study was supported by the Special Coordination Funds for Promoting Science and Technology, the Ministry of Education, Culture, Sports, Science and Technology, Japan (to Y.S.).
Functional studies for the TRAF6 mutation associated with hypohidrotic ectodermal dysplasia
Article first published online: 13 DEC 2012
© 2012 The Authors. BJD © 2012 British Association of Dermatologists
British Journal of Dermatology
Volume 168, Issue 3, pages 629–633, March 2013
How to Cite
Fujikawa, H., Farooq, M., Fujimoto, A., Ito, M. and Shimomura, Y. (2013), Functional studies for the TRAF6 mutation associated with hypohidrotic ectodermal dysplasia. British Journal of Dermatology, 168: 629–633. doi: 10.1111/bjd.12018
Conflicts of interest None declared.
- Issue published online: 28 FEB 2013
- Article first published online: 13 DEC 2012
- Accepted manuscript online: 27 AUG 2012 10:20AM EST
- Accepted for publication 17 August 2012
Background Hypohidrotic ectodermal dysplasia (HED) is a rare condition characterized by hypotrichosis, hypohidrosis and hypodontia. A de novo heterozygous mutation in the tumour necrosis factor receptor-associated factor 6 gene (TRAF6) was recently identified in a patient with HED, while functional consequences resulting from the mutation remained unknown.
Objectives To determine the mechanism by which the TRAF6 mutation results in HED.
Methods We performed coimmunoprecipitation (co-IP) studies to determine whether the mutation would affect the interaction of TRAF6 with transforming growth factor β-activated kinase 1 (TAK1), TAK1-binding protein 2 (TAB 2) and ectodysplasin-A receptor-associated death domain protein (EDARADD). We then performed co-IP and glutathione S-transferase-pulldown assays to determine the TRAF6 binding sequences in EDARADD. In addition, we analysed the effect of the mutant TRAF6 protein on the affinity between wild-type TRAF6 and EDARADD, as well as on EDARADD-mediated nuclear factor (NF)-κB activation.
Results The mutant TRAF6 protein was capable of forming a complex with TAK1 and TAB 2 in a similar way to wild-type TRAF6. However, the mutant TRAF6 protein completely lost the affinity to EDARADD, while the wild-type TRAF6 bound to the N-terminal domain of EDARADD. Furthermore, the mutant TRAF6 inhibited the interaction between the wild-type TRAF6 and EDARADD, and also potentially reduced the EDARADD-mediated NF-κB activity.
Conclusions We conclude that the mutant TRAF6 protein shows a dominant negative effect against the wild-type TRAF6 protein, which is predicted to affect the EDARADD-mediated activation of NF-κB during the development of ectoderm-derived organs, and to lead to the HED phenotype.