Project description:Autoimmune regulator (Aire) is a unique transcriptional regulator that induces promiscuous expression of thousands of tissue-restricted antigens (TRAs) in medullary thymic epithelial cells (mTECs), a step critical for induction of immunological self-tolerance. Although several recent studies provided very important molecular insights into how Aire operates, a more comprehensive understanding of this process still remains elusive. Here we demonstrate that a lysine deacetylase Sirtuin-1 (Sirt1) is predominantly expressed in mature Aire+ mTECs, where it is required for expression of Aire-dependent TRA genes and a subsequent induction of immunological self-tolerance. Our study elucidates a previously unknown molecular mechanism for Aire-mediated transcriptional regulation and uncovers a unique functional role for Sirt1 in preventing organ-specific autoimmunity.
Project description:Autoimmune regulator (Aire) is a unique transcriptional regulator that induces promiscuous expression of thousands of tissue-restricted antigens (TRAs) in medullary thymic epithelial cells (mTECs), a step critical for induction of immunological self-tolerance. Although several recent studies provided very important molecular insights into how Aire operates, a more comprehensive understanding of this process still remains elusive. Here we demonstrate that a lysine deacetylase Sirtuin-1 (Sirt1) is predominantly expressed in mature Aire+ mTECs, where it is required for expression of Aire-dependent TRA genes and a subsequent induction of immunological self-tolerance. Our study elucidates a previously unknown molecular mechanism for Aire-mediated transcriptional regulation and uncovers a unique functional role for Sirt1 in preventing organ-specific autoimmunity. ~100ng of total RNA isolated by Trizol extraction from MHC-II low and high mTECs (pool of 3 mice) was used to generate poly-A-selected transcriptome libraries using the non-directionnal TruSeq V3 RNA Sample Prep Kit (without additional pre-amplification) following the manufacturer's protocols. Enrichment of DNA fragment with adapter molecules on both ends was done using 15 cycles of PCR amplification using the Illumina PCR mix and primer cocktail. Paired-end (2 × 100 bp) sequencing was performed using the Illumina HiSeq2000 machine.
Project description:Medullary thymic epithelial cells play essential role for induction of central self-tolerance. This functional capacity is mediated through a phenomenon known as promiscuous gene expression (pGE) of various tissue-restricted antigen (TRA) genes. pGE was previously shown to be mediated by a single factor called the Autoimmune regulator (Aire), which is specically expressed by mTECs. The aim of this study was to analyze the impact of deacetylase Sirtuin1, which is also highly expressed by mTECs, on mTEC gene expression profile and compare it with the impact of Aire. We used Affymetrix mouse 1ST arrays to analyze the impact of the Sirt1 gene on the gene expression profile of MHC-II high medullary thymic epithelial cells
Project description:Medullary thymic epithelial cells play essential role for induction of central self-tolerance. This functional capacity is mediated through a phenomenon known as promiscuous gene expression (pGE) of various tissue-restricted antigen (TRA) genes. pGE was previously shown to be mediated by a single factor called the Autoimmune regulator (Aire), which is specically expressed by mTECs. The aim of this study was to analyze the impact of deacetylase Sirtuin1, which is also highly expressed by mTECs, on mTEC gene expression profile and compare it with the impact of Aire. We used Affymetrix mouse 1ST arrays to analyze the impact of the Sirt1 gene on the gene expression profile of MHC-II high medullary thymic epithelial cells Mature MHC-II high mTECs were flow-sorted from thymi isolated from B6.Sirt1fl/fl, B6.Sirt1fl/flFoxn1-Cre and B6.Aire–/– 6weeks old mice. Typically, 3 mice were pooled to obtain 30-60 thousand sorted mTECs, which were then analyzed by gene expression profiling. Specifically, total RNA was extracted from ~30,000 pooled sorted cells using Trizol. Purified total RNA was then amplified using the MessageAmp RNA kit (Ambion). Biotinylated cRNA was then hybridized to Affymetrix Mouse Gene 1-ST arrays by the genomics core at the Weizmann Institute
Project description:The autoimmune regulator, AIRE, induces the transcription of thousands of peripheral tissue genes (PTGs) in thymic epithelial cells (TECs) to mediate immunological tolerance. The chromatin state required for optimal AIRE function in TECs and how this state is induced remains unclear. Using RNA-seq and ATAC-seq, we tested the role of the histone acetyltransferase, KAT7 (also known as HBO1 or MYST2), which is essential for acetylation of histone 3 lysine 14 (H3K14), in TEC differentiation, AIRE-mediated PTG expression and thymic tolerance. We find that KAT7 is required for optimal expansion of medullary TEC and has a major role in the expression of AIRE-dependent PTGs, associated with enhanced chromatin accessibility at these gene loci in TECs. Mice with TEC-specific Kat7 deletion develop organ-specific autoimmunity with features resembling those observed in Aire-deficient mice. These findings highlight critical roles for KAT7-mediated acetylation in promoting a chromatin state at PTG loci that enables AIRE function and the establishment of immunological tolerance.
Project description:Mutations in the gene encoding the transcription factor AutoImmune REgulator (AIRE) are responsible for the ‘Autoimmune PolyEndocrinopathy Candidiasis Ecodermal Dystrophy’ syndrome. AIRE directs expression of tissue restricted antigens in the thymic medulla and in lymph node stromal cells and thereby substantially contributes to induction of immunological tolerance to self-antigens. Data from experimental mouse models showed that AIRE-deficiency leads to impaired deletion of autospecific T cell precursors. However, a potential role for AIRE in the function of regulatory T cell populations, which are known to play a central role in prevention of immunopathology, has remained elusive. Regulatory T cells of CD8+CD28low phenotype efficiently control immune responses in experimental autoimmune and colitis models in mice. We here show that CD8+CD28low Treg from AIRE-deficient mice are transcriptionally and phenotypically normal, exert efficient suppression of in vitro immune responses, but completely fail to prevent experimental colitis in vivo. Our data therefore demonstrate that AIRE plays an important role in the in vivo function of a naturally occurring regulatory T cell population. Total RNA was extracted from CD8+CD28low regulatory T lymphocytes isolated from wildtype and Aire-deficient C57BL/6 mice for comparison of gene expression profiles.