Abstract
Triple A syndrome is a rare autosomal recessive disorder characterized by ACTH-resistant adrenal failure, alacrima, achalasia, and progressive neurological manifestations. The majority of cases are associated with mutations in the AAAS gene, which encodes a novel, 60-kDa WD-repeat nuclear pore protein, alacrima-achalasia-adrenal insufficiency neurological disorder (ALADIN) of unknown function. Our aim was to elucidate the functional role of ALADIN by determining its interacting protein partners using the bacterial two-hybrid (B2-H) technique. Nonidentical cDNA fragments were identified from both a HeLa S-3 cell and human cerebellar cDNA library that encoded the full-length ferritin heavy chain protein (FTH1). This interaction was confirmed by both co-immunoprecipitation and fluorescence lifetime imaging microscopy-fluorescence resonance energy transfer studies. Immunoblotting showed that fibroblasts from triple A patients (with known AAAS mutations) lack nuclear FTH1, suggesting that the nuclear translocation of FTH1 is defective. Cells transfected with FTH1 and visualized by confocal microscopy had very little nuclear FTH1, but when cotransfected with AAAS, FTH1 is readily visible in the nuclei. Therefore, FTH1 nuclear translocation is enhanced when ALADIN is coexpressed in these cells. In addition to its well known iron storage role, FTH1 has been shown to protect the nucleus from oxidative damage. Apoptosis of neuronal cells induced by hydrogen peroxide was significantly reduced by transfection of AAAS or by FTH1 or maximally by both genes together. Taken together, this work offers a plausible mechanism for the progressive clinical features of triple A syndrome. (Molecular Endocrinology 23: 2086–2094, 2009)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
More From: The Journal of Clinical Endocrinology & Metabolism
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.