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Summary 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.

Frischmeyer PA, 1999, HUM MOL GENET, V8, P1893, DOI 10.1093-hmg-8.10.1893; GROSSMAN M, 1990, INT J DERMATOL, V29, P535, DOI 10.1111-j.1365-4362.1990.tb03463.x; Kiuru M, 2011, AM J HUM GENET, V88, P839, DOI 10.1016-j.ajhg.2011.05.014; Mecklenburg L, 2004, J INVEST DERMATOL, V123, P1001, DOI 10.1111-j.0022-202X.2004.23442.x; Nakamura Y, 2003, EMBO J, V22, P2981, DOI 10.1093-emboj-cdg302; Nakamura Y, 2008, FASEB J, V22, P841, DOI 10.1096-fj.07-9239com; NIWA H, 1991, GENE, V108, P193; Norgett EE, 2004, BRIT J DERMATOL, V151, P65, DOI 10.1111-j.1365-2133.2004.05994.x; Schlake T, 2000, DEV DYNAM, V217, P368, DOI 10.1002-(SICI)1097-0177(200004)217:4368::AID-DVDY43.0.CO;2-Z; Stewart AJ, 2005, INT J MOL MED, V15, P117