Mutations in the AIRE gene: Effects on subcellular location and transactivation function of the autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy protein

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a monogenic autosomal disease with recessive inheritance. It is characteriz ed by multiple autoimmune endocrinopathies, chronic mucocutaneous candidias is, and ectodermal dystrophies. The defective gene responsible for this dis ease was recently isolated, and several different mutations in the novel ge ne, AIRE, have been identified, by us and by others, in patients with APECE D. We have shown that the APECED protein is mainly localized, both in vitro and in vivo, to the cell nucleus, where it forms distinct speckles. This a ccords with the predicted structural features of the protein, which suggest involvement of AIRE in the regulation of gene transcription. Here, we repo rt the results of mutational analyses of a series of 112 patients with APEC ED who were from various ethnic backgrounds. A total of 16 different mutati ons, covering 91% of disease alleles, were observed; of these, 8 were novel . The mutations are spread throughout the coding region of AIRE, yet four e vident mutational hotspots were observed. In vitro expression of four diffe rent naturally occurring nonsense and missense mutations revealed a dramati cally altered subcellular location of the protein in cultured cells. Intere stingly, the wild-type APECED protein tethered to the Gal4 DNA-binding doma in acted as a strong transcriptional activator of reporter genes in mammali an cells, whereas most of the analyzed mutant polypeptides had lost this ca pacity.