Endocrine Abstracts

Triple A syndrome is is a rare autosomal recessive disorder characterised by achalasia, alacrima, adrenocorticotropin-resistant adrenal insufficiency and a variable and progressive neurological phenotype. The AAAS gene encodes a 60kD WD-repeat nuclear pore protein named ALADIN (alacrima, achalasia, adrenal insufficiency neurologic disorder); its function and tissue distribution are unknown. In this study we performed in situ hybridization with 35S end-labelled AAAS mRNA oligonucleotide probes in the adult and developing rat and present the first detailed map of AAAS mRNA expression. Controls included competition of specific labelling with excess unlabeled homologous oligonucleotide. After hybridisation and appropriate washes, dried sections were apposed to autoradiographic film in order to visualise the general pattern of the mRNA in the tissues. Emulsion autoradiography allowed analysis of the mRNA at a cellular resolution. Four in situ hybridisation probes to AAAS mRNA produced identical results. Addition of excess unlabelled oligonucleotides effectively competed specific binding of radiolabelled probe. We detected high levels of AAAS mRNA in the adrenal cortex, but with no zonal difference. In both the peripheral and central nervous systems (CNS), AAAS mRNA was abundantly expressed. Neurons in the sensory and sympathetic ganglia expressed high levels and CNS expression was highest in neurons of the cerebral cortex, cerebellum, hippocampus, motor-associated nuclei of the brainstem including cranial nerve nuclei, and ventral horn of the spinal cord. High levels were also found in the pituitary gland. Within the developing embryo, the highest levels of expression were found in neural tissues. These findings indicate a widespread but not ubiquitous or uniform expression of AAAS mRNA in the rat. Robust expression in the adrenal and neural systems associated with cognitive, motor and sensory functions are consistent the phenotypic abnormalities in this disorder. These data, in addition to our ongoing work should provide a valuable insight into the pathogenesis of the Triple A syndrome.