ABSTRACT: Thymic medullary epithelial cell (mTEC) expression of the autoimmune regulator AIRE, and of tissue-specific antigens, is controlled by members of the non-canonical NF-kB signalling pathway, including RelB and NF-kB2. Of the genes in this pathway, RelB-/- mice develop a particularly severe multi-organ autoimmune syndrome, resembling Foxp3-deficiency. RelB-/- mice have medullary atrophy and few mTECs but the mechanism is unknown. We show that RelB is required for expression of medullary chemokines and mTEC AIRE, selection of a diverse peripheral T cell repertoire, and for peripheral Foxp3+ Treg function. Vβ families of T cells infiltrating diseased peripheral organs and thymic Treg were similarly skewed. Surprisingly, medullary atrophy results from intra-thymic granulocyte infiltration, consequent upon the Th2-mediated autoimmune disease. Dominant tolerance corrects thymic inflammatory disease and loss of thymic function. We demonstrate a reversible RelB-dependent inflammatory mechanism for loss of central tolerance associated with medullary atrophy.
Project description:Thymic medullary epithelial cell (mTEC) expression of the autoimmune regulator AIRE, and of tissue-specific antigens, is controlled by members of the non-canonical NF-kB signalling pathway, including RelB and NF-kB2. Of the genes in this pathway, RelB-/- mice develop a particularly severe multi-organ autoimmune syndrome, resembling Foxp3-deficiency. RelB-/- mice have medullary atrophy and few mTECs but the mechanism is unknown. We show that RelB is required for expression of medullary chemokines and mTEC AIRE, selection of a diverse peripheral T cell repertoire, and for peripheral Foxp3+ Treg function. Vβ families of T cells infiltrating diseased peripheral organs and thymic Treg were similarly skewed. Surprisingly, medullary atrophy results from intra-thymic granulocyte infiltration, consequent upon the Th2-mediated autoimmune disease. Dominant tolerance corrects thymic inflammatory disease and loss of thymic function. We demonstrate a reversible RelB-dependent inflammatory mechanism for loss of central tolerance associated with medullary atrophy. Thymi from 4 RelB+/- mice and 3 RelB-/- mice were profiled by microarays
Project description:Medullary thymic epithelial cells (mTECs) contribute to self-tolerance through the ectopic expression of peripheral tissue antigens (PTAs) in the thymus. PTA expression in mTECs is largely dependent on the autoimmune regulator (Aire) gene. Here we used a Mus musculus mTEC cell line (3.10 mTEC line, which constitutively express Aire in culture) to knockdown Aire gene by means of siRNA transfection. Aire knockdown was confirmed by means of qRT-PCR and RNA-FISH (for Aire mRNA levels), immunofluorescence and western blot (for AIRE protein levels).The Agilent oligo microarrays were used to determine the large scale transcriptional expression profiles of control or Aire-knockdown 3.10 mTECs.
Project description:Medullary thymic epithelial cells (mTECs) contribute to self-tolerance through the ectopic expression of peripheral tissue antigens (PTAs) in the thymus. Autoimmune regulator (Aire) is to date the best characterized transcriptional regulator known to at least partially coordinate PTA expression in mTECs. Furthermore the expression of Aire-dependent and -independent genes is also modulated by microRNAs. Given the transcriptional regulation exerted by Aire in mTEC cells and the role of miRNAs in post-transcriptional control, we used a Mus musculus mTEC cell line (3.10) which constitutively express Aire in culture) to knockdown Aire gene by means of siRNA transfection and then observe the effect of Aire knockdown in the transcriptional profile of miRNAs by means of oligomicroarrays. The Agilent oligomicroarrays were used to determine the large scale the miRNA transcriptional profiles of control or Aire-knockdown 3.10 mTECs.
Project description:Thymic epithelial cells govern thymic T lymphocyte differentiation and selection. Medullary TECs (mTECs) facilitate the negative selection of self-reactive thymocytes and the differentiation of FOXP3+ regulatory T cells. Medullary TECs are also distinctive for their “promiscuous” gene expression, transcribing thousands of peripheral tissue genes (PTG) that are otherwise only expressed highly in one or two other organs. Much of this PTG expression by mTECs is controlled by the autoimmune regulator, AIRE. To probe the mechanism by which KAT7 promotes AIRE function, we performed ATAC-seq to compare chromatin accessibility in MHCII-high medullary thymic epithelial cells from Kat7-knockout and wildtype mice.
Project description:Promiscuous gene expression (pGE) of numerous self-antigens in thymic epithelial cells (TEC) enables the elimination of self-reactive T cells. The autoimmune regulator (Aire) is the only known molecular determinant driving pGE in the thymus but the existence of Aire-independent mechanisms has been inferred. Here, we analyzed the poly(A)+ transcriptome of TEC populations by RNA-sequencing (RNA-seq) in order to reveal differential features of Aire-induced vs. –independent pGE. We report an unanticipated effect of Aire deletion on the proliferation and differentiation of cortical TEC. Moreover, the RNA-seq data reveal the breath of Aire-induced and –independent pGE in medullary TEC (mTEC) subsets and the extent of thymic peripheral tissue representation. The results suggest that Aire-induced promiscuously expressed transcripts affect several functions with far reaching biological consequences in mTEC. High-throughput characterization of TEC transcriptomes will enable progress in understanding TEC biology and the establishment of self-tolerance. The mRNA profiles of cTEC, mTEClo and mTEChi from 6-8 week-old wild type (WT) and Aire-/- (KO) mice were generated by RNA-sequencing using Illumina HiSeq2000.
Project description:In this study, we used the murine (Mus musculus) medullary thymic epithelial cell line (mTEC 3.10 cell line) co-cultured with fresh thymocytes as a functional assay for mTEC-thymocyte adhesion. Then we analyzed the differential transcriptional profile of this cell line, by means of Agilent oligo microarray hybridization, comparing Autoimmune regulator (Aire) wild-type cells vs Crispr-Cas9-induced Aire KO cells. The comparative transcriptional expression signatures allowed us to find those differentially expressed mRNAs or lncRNAs between the samples tested.
Project description:The crosstalk between thymocytes and thymic epithelial cells is critical for T cell development and establishment of central tolerance. Although the role of Autoimmune Regulator (Aire) gene in the induction of central tolerance is well known, the precise cellular and molecular mechanisms by which Aire controls the ectopic expression of tissue restricted antigens (TRAs) in medullary thymic epithelial cells (mTECS) remain unclear. In this study we performed a functional assay with fresh thymocytes dissociated from a normal mouse thymus co-cultured with a Mus musculus mTEC cell line - named 3.10 mTEC line - , in which we had previously knocked-down Aire gene by means of siRNA transfection. Agilent Mouse Gene Expression microarrays were used to determine the large scale transcriptional expression profiles of control and Aire-knockdown 3.10 mTECs co-cultured with thymocytes.
Project description:Promiscuous gene expression (pGE) of numerous self-antigens in thymic epithelial cells (TEC) enables the elimination of self-reactive T cells. The autoimmune regulator (Aire) is the only known molecular determinant driving pGE in the thymus but the existence of Aire-independent mechanisms has been inferred. Here, we analyzed the poly(A)+ transcriptome of TEC populations by RNA-sequencing (RNA-seq) in order to reveal differential features of Aire-induced vs. –independent pGE. We report an unanticipated effect of Aire deletion on the proliferation and differentiation of cortical TEC. Moreover, the RNA-seq data reveal the breath of Aire-induced and –independent pGE in medullary TEC (mTEC) subsets and the extent of thymic peripheral tissue representation. The results suggest that Aire-induced promiscuously expressed transcripts affect several functions with far reaching biological consequences in mTEC. High-throughput characterization of TEC transcriptomes will enable progress in understanding TEC biology and the establishment of self-tolerance.
Project description:Insm1, encoding a zinc finger protein, is expressed specifically in neuroendocrine cells. Recent study showed the first evidence of Insm1 expression in medullary thymic epithelial cells (mTEC). Here we investigated the expression and function of Insm1 in mTEC. Mutation of Insm1 resulted in decreased proportion of mTEChi although normal development of other types of thymic cells. We detected altered expression of a subset of tissue-restricted antigens (TRAs) and mild decreased expression of Aire and Fezf2 in Insm1 mutant mTEC. We further showed that Insm1 recognizes a DNA sequence which is similar to the CCCTC-Binding factor (CTCF) binding motif. Mutation of Insm1 altered CTCF binding genome widely and thus the expression of genes. In nude mice transplanted with Insm1 mutant thymus, autoimmune responses were observed in multiple peripheral tissues. In thymus specific Insm1 mutant mice, we detected decreased induction of regulatory T (Treg) cells in the thymus, obvious lymphocytes infiltration and autoimmune antibody reaction in several peripheral tissues. In thymic epithelial cells specific Insm1 overexpression mice, we detected enlarged mTEC proportion and increased expression of mTEC specific genes. Thus, we suggest that Insm1 is a novel regulator of mTEC function and autoimmunity.
Project description:Insm1, encoding a zinc finger protein, is expressed specifically in neuroendocrine cells. Recent study showed the first evidence of Insm1 expression in medullary thymic epithelial cells (mTEC). Here we investigated the expression and function of Insm1 in mTEC. Mutation of Insm1 resulted in decreased proportion of mTEChi although normal development of other types of thymic cells. We detected altered expression of a subset of tissue-restricted antigens (TRAs) and mild decreased expression of Aire and Fezf2 in Insm1 mutant mTEC. We further showed that Insm1 recognizes a DNA sequence which is similar to the CCCTC-Binding factor (CTCF) binding motif. Mutation of Insm1 altered CTCF binding genome widely and thus the expression of genes. In nude mice transplanted with Insm1 mutant thymus, autoimmune responses were observed in multiple peripheral tissues. In thymus specific Insm1 mutant mice, we detected decreased induction of regulatory T (Treg) cells in the thymus, obvious lymphocytes infiltration and autoimmune antibody reaction in several peripheral tissues. In thymic epithelial cells specific Insm1 overexpression mice, we detected enlarged mTEC proportion and increased expression of mTEC specific genes. Thus, we suggest that Insm1 is a novel regulator of mTEC function and autoimmunity.