A deep intronic splice-altering AIRE variant causes APECED syndrome through antisense oligonucleotide-targetable pseudoexon inclusion
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ABSTRACT: Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a life-threatening monogenic autoimmune disorder primarily caused by biallelic deleterious variants in the autoimmune regulator (AIRE) gene. We prospectively evaluated 104 patients with clinically diagnosed APECED syndrome and identified 17 patients (16%) from 14 kindreds lacking biallelic AIRE variants in exons or flanking intronic regions; 15 had Puerto Rican ancestry. Through whole-genome sequencing, we identified a deep intronic AIRE variant (c.1504-818 G>A) cosegregating with the disease in all 17 patients. We developed a culture system of AIRE-expressing primary patient monocyte-derived dendritic cells and demonstrated that c.1504-818 G>A creates a cryptic splice site and activates inclusion of a 109-base pair frame-shifting pseudoexon. We also found low-level AIRE expression in patient-derived lymphoblastoid cell lines (LCLs) and confirmed pseudoexon inclusion in independent extrathymic AIRE-expressing cell lines. Through protein modeling and transcriptomic analyses of AIRE-transfected human embryonic kidney 293 and thymic epithelial cell 4D6 cells, we showed that this variant alters the carboxyl terminus of the AIRE protein, abrogating its function. Last, we developed an antisense oligonucleotide (ASO) that reversed pseudoexon inclusion and restored the normal AIRE transcript sequence in LCLs. Thus, our findings revealed c.1504-818 G>A as a founder APECED-causing AIRE variant in the Puerto Rican population and uncovered pseudoexon inclusion as an ASO-reversible genetic mechanism underlying APECED.
Project description:Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a monogenic autoimmune disease caused by mutations in the AIRE gene. AIRE functions as a transcriptional regulator and it has a central role in the development of immunological tolerance. AIRE regulates the expression of ectopic antigens in epithelial cells of the thymic medulla and has been shown to participate in the development of peripheral tolerance. However, the mechanism of action of AIRE has remained elusive. To further investigate the role of AIRE in host immune functions, using microarray technology, we studied the properties and transcript profiles in in vitro monocyte-differentiated dendritic cells (moDCs) obtained from APECED patients and healthy controls. Keywords: patient vs. healthy control comparative analysis
Project description:Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a monogenic autoimmune disease caused by mutations in the AIRE gene. AIRE functions as a transcriptional regulator and it has a central role in the development of immunological tolerance. AIRE regulates the expression of ectopic antigens in epithelial cells of the thymic medulla and has been shown to participate in the development of peripheral tolerance. However, the mechanism of action of AIRE has remained elusive. To further investigate the role of AIRE in host immune functions, using microarray technology, we studied the properties and transcript profiles in in vitro monocyte-differentiated dendritic cells (moDCs) obtained from APECED patients and healthy controls. Experiment Overall Design: This study includes three female APECED patients between the ages of 26 and 51 years and all patients carried the homozygote FinnMajor mutation (R257X) in the AIRE gene. As controls, we used buffy coats from helathy voluntary blood donors obtained from the Finnish Red Cross Transfusion Service (Helsinki, Finland). The controls were sex- and age-matched. Peripheral blood mononuclear cells (PBMC) were isolated from these subjects. The PBMCs were stimulated to differentiate into mature moDCs. RNA harvested from these cells was labeled and hybridized into microarrays. Part of the cells were treated with candida albicans. RNA from these cells was similarly labeled and studied with mocroarrays.
Project description:APECED is a monogenic autoimmune disease caused by defects in Autoimmune Regulator (AIRE) gene that promotes the expression of self-antigens in the thymus. The autoimmune phenotype in APECED is variable, and multiple proteins are targeted by autoantibodies. This study used human protein arrays to screen autoantibody targets in APECED and to identify novel autoimmune targets. Altogether 100 sera samples from 82 individual APECED patients were profiled using Protoarray antibody specificity service at Invitrogen as well as samples from 12 healthy controls and 8 healthy relatives. The protein arrays (ProtoArray v5.1) were probed as described in Invitrogenâs protocol for Immune Response BioMarker Profiling using detection reagent (Alexa Fluor 647 Goat Anti-Human IgG A21445, Invitrogen) and blocking buffer (Blocking Buffer Kit PA055, Invitrogen). Arrays were scanned using a GenePix 4000B fluorescent scanner, and the data was acquired with GenePix® Pro software. The arrays were probed with sera at a dilution of 1:500.
Project description:The objective of this study was to understand the impact of autoimmune regulator (AIRE) on immunity against oral Candida albicans infection. Previous work indicated that autoantibodies against IL-17 and IL-22 may contribute to host susceptibility; however, there is not a 100% correlation between autoantibodies and mucosal candidiasis in autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED) patients, indicating that other pathways may be affected. Using a mouse model that very closely mimics what is seen in APECED patients, oral epithelial cells were sorted and RNA extracted from them to perform RNA-seq analysis to determine what other pathways may be involved. These data show that the type II interferon pathway is highly upregulated in Aire-deficient mice, while the IL-17R pathway is intact.
Project description:Aire is an important transcription regulator that mediates a role in central tolerance via promoting the promiscuous expression of tissue-specific antigens in the thymus. Although several mouse models of Aire-deficiency have been described, none has analysed the phenotype induced by a mutation that emulates the common 13bp deletion in human APECED by disrupting the first PHD domain in exon 8. Aire-deficient mice with a corresponding mutation showed some disturbance of the medullary epithelial compartment, but at the phenotypic level their T cell compartment appeared relatively normal in the thymus and periphery. An increase in the number of activated T cells was evident, and autoantibodies against several organs were detected. At the histological level, lymphocytic infiltration of several organs indicated the development of autoimmunity, though symptoms were mild and quality of life for Aire-deficient mice appeared equivalent to wild-type littermates, with the exception of male infertility. Vbeta and CDR3 length analysis suggested that each Aire-deficient mouse developed it own polyclonal autoimmune repertoire. Finally, given the prevalence of candidiasis in APECED patients, we examined the control of infection with Candida albicans in Aire-deficient mice. No increase in disease susceptibility was found for either oral or systematic infection. These observations support the view that additional genetic and/or environmental factors contribute substantially to the overt nature of autoimmunity associated with Aire mutations, even for mutations identical to those found in humans with APECED. Keywords: Gene expression comparison between genotypes In this experiment there are 5 samples altogether which consist of two biological replicates of Aire knock-out mTECs and 3 biological replicates of wild type mTECs.
Project description:Aire is an important transcription regulator that mediates a role in central tolerance via promoting the promiscuous expression of tissue-specific antigens in the thymus. Although several mouse models of Aire-deficiency have been described, none has analysed the phenotype induced by a mutation that emulates the common 13bp deletion in human APECED by disrupting the first PHD domain in exon 8. Aire-deficient mice with a corresponding mutation showed some disturbance of the medullary epithelial compartment, but at the phenotypic level their T cell compartment appeared relatively normal in the thymus and periphery. An increase in the number of activated T cells was evident, and autoantibodies against several organs were detected. At the histological level, lymphocytic infiltration of several organs indicated the development of autoimmunity, though symptoms were mild and quality of life for Aire-deficient mice appeared equivalent to wild-type littermates, with the exception of male infertility. Vbeta and CDR3 length analysis suggested that each Aire-deficient mouse developed it own polyclonal autoimmune repertoire. Finally, given the prevalence of candidiasis in APECED patients, we examined the control of infection with Candida albicans in Aire-deficient mice. No increase in disease susceptibility was found for either oral or systematic infection. These observations support the view that additional genetic and/or environmental factors contribute substantially to the overt nature of autoimmunity associated with Aire mutations, even for mutations identical to those found in humans with APECED. Keywords: Gene expression comparison between genotypes
Project description:RNA-Sequencing performed on 177 honey bee whole-brains, divided into "soldier" and "forager" groups from Puerto Rican honey bee colonies.
Project description:The Autoimmune Regulator (AIRE) protein is the key factor in thymic negative selection of autoreactive T-cells by promoting the ectopic expression of tissue-specific genes in thymic medullary epithelium. Mutations in AIRE cause a monogenic autoimmune disease called autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED). AIRE has been shown to promote DNA breaks via its interaction with topoisomerase 2 (TOP2). In this study, we investigated topoisomerase-induced DNA breaks and chromatin structural alterations in conjunction with AIRE-dependent gene expression. Using RNA-seq, we found that the inhibition of TOP2 religation activity by etoposide in AIRE-expressing cells had a synergistic effect on genes with low expression levels. AIRE-mediated transcription was not only enhanced by TOP2 inhibition but also by topoisomerase 1 (TOP1) inhibitor camptothecin. The transcriptional activation was associated with structural rearrangements in chromatin, notably the accumulation of γH2AX and the exchange of histone H1 with HMGB1 at AIRE target gene promoters. In addition, we found the transcriptional upregulation to co-occur with the chromatin structural changes within the genomic cluster of carcino-embryonic antigen-like cellular adhesion molecule (CEACAM) genes. Overall, our results suggest that the presence of AIRE can trigger molecular events leading to an altered chromatin landscape and the enhanced transcription of low-expressed genes.
Project description:The Autoimmune Regulator (AIRE) protein is the key factor in thymic negative selection of autoreactive T-cells by promoting the ectopic expression of tissue-specific genes in thymic medullary epithelium. Mutations in AIRE cause a monogenic autoimmune disease called autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED). AIRE has been shown to promote DNA breaks via its interaction with topoisomerase 2 (TOP2). In this study, we investigated topoisomerase-induced DNA breaks and chromatin structural alterations in conjunction with AIRE-dependent gene expression. Using RNA-seq, we found that the inhibition of TOP2 religation activity by etoposide in AIRE-expressing cells had a synergistic effect on genes with low expression levels. AIRE-mediated transcription was not only enhanced by TOP2 inhibition but also by topoisomerase 1 (TOP1) inhibitor camptothecin. The transcriptional activation was associated with structural rearrangements in chromatin, notably the accumulation of γH2AX and the exchange of histone H1 with HMGB1 at AIRE target gene promoters. In addition, we found the transcriptional upregulation to co-occur with the chromatin structural changes within the genomic cluster of carcino-embryonic antigen-like cellular adhesion molecule (CEACAM) genes. Overall, our results suggest that the presence of AIRE can trigger molecular events leading to an altered chromatin landscape and the enhanced transcription of low-expressed genes.