AIRE-PHD fingers are structural hubs to maintain the integrity of chromatin-associated interactome.
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.
Biomolecular NMR Laboratory, Center of Translational Genomics and Bioinformatics, Dulbecco Telethon Institute c/o S. Raffaele Scientific Institute, Milano, Italy.
Massimiliano
M
Gaetani
Vittoria
V
Matafora
Mario
M
Saare
Dimitrios
D
Spiliotopoulos
Luca
L
Mollica
Giacomo
G
Quilici
Francesca
F
Chignola
Valeria
V
Mannella
Chiara
C
Zucchelli
Pärt
P
Peterson
Angela
A
Bachi
Giovanna
G
Musco
D002843:Chromatin / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D008958:Models, Molecular; D009154:Mutation; D017434:Protein Structure, Tertiary; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000096927:AIRE Protein
D002843:Chromatin; D014157:Transcription Factors; D000096927:AIRE Protein