Department of Dermatology, Yamaguchi University Graduate School of Medicine, Ube, Japan.
Division of Dermatology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
J Dermatol. 2021 Oct;48(10):1533-1541. doi: 10.1111/1346-8138.16044. Epub 2021 Jul 4.
Hypohidrotic ectodermal dysplasia (HED) is a genetic disorder characterized by hypohidrosis, hypodontia, and hypotrichosis. Autosomal forms of the disease are caused by mutations in either EDAR or EDARADD. To date, the underlying pathomechanisms for HED resulting from EDARADD mutations have not fully been disclosed. In this study, we performed detailed in vitro analyses in order to characterize three dominantly inherited missense mutations, p.D120Y, p.L122R, and p.D123N, and one recessively inherited missense mutation, p.E152K, in the EDARADD gene. Nuclear factor (NF)-κB reporter assays demonstrated that all the mutant EDARADD showed reduction in activation of NF-κB. Importantly, p.D120Y-, p.L122R-, and p.D123N-mutant EDARADD slightly reduced the NF-κB activity induced by wild-type EDARADD in a dominant negative manner. Co-immunoprecipitation assays showed that all of the mutant EDARADD were capable of binding to EDAR and wild-type EDARADD. Additional co-immunoprecipitation assays revealed that p.D120Y-, p.L122R-, and p.D123N-mutant EDARADD markedly prevented the interaction between EDAR and wild-type EDARADD, which further indicated a dominant negative effect by these mutations. Finally, we found that p.D120Y-, p.L122R-, and p.D123N-mutant EDARADD completely lost the ability to bind with TRAF6, while p.E152K-mutant EDARADD showed a mild reduction in the affinity. Our findings will provide crucial information toward unraveling the molecular mechanisms how EDARADD gene mutations cause the disease.
少汗型外胚层发育不全症（HED）是一种遗传性疾病，其特征为少汗、无牙和毛发稀疏。疾病的常染色体形式是由 EDAR 或 EDARADD 中的突变引起的。迄今为止，由 EDARADD 突变引起的 HED 的潜在病理机制尚未完全揭示。在这项研究中，我们进行了详细的体外分析，以表征 EDARADD 基因中的三个显性遗传错义突变 p.D120Y、p.L122R 和 p.D123N，以及一个隐性遗传错义突变 p.E152K。核因子（NF）-κB 报告基因分析表明，所有突变型 EDARADD 的 NF-κB 激活均减少。重要的是，p.D120Y、p.L122R 和 p.D123N 突变型 EDARADD 以显性负性方式轻微降低了野生型 EDARADD 诱导的 NF-κB 活性。共免疫沉淀分析表明，所有突变型 EDARADD 均能与 EDAR 和野生型 EDARADD 结合。另外的共免疫沉淀分析表明，p.D120Y、p.L122R 和 p.D123N 突变型 EDARADD 显著阻止了 EDAR 与野生型 EDARADD 之间的相互作用，这进一步表明这些突变具有显性负效应。最后，我们发现 p.D120Y、p.L122R 和 p.D123N 突变型 EDARADD 完全丧失了与 TRAF6 结合的能力，而 p.E152K 突变型 EDARADD 与 TRAF6 的亲和力则略有降低。我们的研究结果将为阐明 EDARADD 基因突变导致疾病的分子机制提供重要信息。
