AIRE-PHD fingers are structural hubs to maintain the integrity of chromatin-associated interactome

• Published in: Nucleic acids research 2012-12, Vol.40 (22), p.11756-11768
• Main Authors: Gaetani, Massimiliano, Matafora, Vittoria, Saare, Mario, Spiliotopoulos, Dimitrios, Mollica, Luca, Quilici, Giacomo, Chignola, Francesca, Mannella, Valeria, Zucchelli, Chiara, Peterson, Pärt, Bachi, Angela, Musco, Giovanna
• Format: Article
• Language: English
• Subjects: AIRE Protein; Autoimmune polyendocrinopathy candidiasis ectodermal dystrophy; Chromatin; Chromatin - metabolism; Epithelial cells; Finger; Gene regulation; HEK293 Cells; Homeobox; Humans; Immunological tolerance; Models, Molecular; Mutation; Protein interaction; Protein Structure, Tertiary; proteomics; Structural Biology; Thymus; Transcription; Transcription activation; Transcription Factors - chemistry; Transcription Factors - genetics; Transcription Factors - metabolism
• ISSN: 0305-1048; 1362-4962
• DOI: 10.1093/nar/gks933

Mutations in autoimmune regulator (AIRE) gene cause autoimmune polyendocrinopathy candidiasis ectodermal dystrophy. AIRE is expressed in thymic medullary epithelial cells, where it promotes the expression of peripheral-tissue antigens to mediate deletional tolerance, thereby preventing self-reactivity. AIRE contains two plant homeodomains (PHDs) which are sites of pathological mutations. AIRE-PHD fingers are important for AIRE transcriptional activity and presumably play a crucial role in the formation of multimeric protein complexes at chromatin level which ultimately control immunological tolerance. As a step forward the understanding of AIRE-PHD fingers in normal and pathological conditions, we investigated their structure and used a proteomic SILAC approach to assess the impact of patient mutations targeting AIRE-PHD fingers. Importantly, both AIRE-PHD fingers are structurally independent and mutually non-interacting domains. In contrast to D297A and V301M on AIRE-PHD1, the C446G mutation on AIRE-PHD2 destroys the structural fold, thus causing aberrant AIRE localization and reduction of AIRE target genes activation. Moreover, mutations targeting AIRE-PHD1 affect the formation of a multimeric protein complex at chromatin level. Overall our results reveal the importance of AIRE-PHD domains in the interaction with chromatin-associated nuclear partners and gene regulation confirming the role of PHD fingers as versatile protein interaction hubs for multiple binding events.