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APECED‐causing mutations in AIRE reveal the functional domains of the protein
Author(s) -
Halonen Maria,
Kangas Hannele,
Rüppell Taina,
Ilmarinen Tanja,
Ollila Juha,
Kolmer Meelis,
Vihinen Mauno,
Palvimo Jorma,
Saarela Jani,
Ulmanen Ismo,
Eskelin Petra
Publication year - 2004
Publication title -
human mutation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 162
eISSN - 1098-1004
pISSN - 1059-7794
DOI - 10.1002/humu.20003
Subject(s) - transactivation , biology , missense mutation , zinc finger , transcription factor , mutation , microbiology and biotechnology , mutant , transcription (linguistics) , cytoplasm , autoimmune regulator , genetics , gene , linguistics , philosophy
A defective form of the AIRE protein causes autoimmune destruction of target organs by disturbing the immunological tolerance of patients with a rare monogenic disease, autoimmune polyendocrinopathy (APE)–candidiasis (C)–ectodermal dystrophy (ED), APECED. Recently, experiments on knockout mice revealed that AIRE controls autoimmunity by regulating the transcription of peripheral tissue‐restricted antigens in thymic medullary epithelial cells. Thus, AIRE provides a unique model for molecular studies of organ‐specific autoimmunity. In order to analyze the molecular and cellular consequences of 16 disease‐causing mutations in vitro, we studied the subcellular localization, transactivation capacity, homomultimerization, and complex formation of several mutant AIRE polypeptides. Most of the mutations altered the nucleus–cytoplasm distribution of AIRE and disturbed its association with nuclear dots and cytoplasmic filaments. While the PHD zinc fingers were necessary for the transactivation capacity of AIRE, other regions of AIRE also modulated this function. Consequently, most of the mutations decreased transactivation. The HSR domain was responsible for the homomultimerization activity of AIRE; all the missense mutations of the HSR and the SAND domains decreased this activity, but those in other domains did not. The AIRE protein was present in soluble high‐molecular‐weight complexes. Mutations in the HSR domain and deletion of PHD zinc fingers disturbed the formation of these complexes. In conclusion, we propose an in vitro model in which AIRE transactivates transcription through heteromeric molecular interactions that are regulated by homomultimerization and conditional localization of AIRE in the nucleus or in the cytoplasm. Hum Mutat 23:245–257, 2004. © 2004 Wiley‐Liss, Inc.