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:Aire is a transcriptional regulator that induces promiscuous expression of thousands of tissue-restricted antigen (TRA) genes in medullary thymic epithelial cells (mTECs). While the target genes of Aire are well characterized, the transcriptional programs regulating its own expression remain elusive. We used Affymetrix microarrays to analyze the gene expression patterns of Aire expressing cells (mature mTECs and Thymic B cells) and compared them to control counterparts, namely immature mTECs, cortical Thymic epithelial cells and splenic B cells of tissue-restricted antigen (TRA) genes in medullary thymic epithelial cells (mTECs). While the target genes of Aire are well characterized, the transcriptional programs regulating its own expression remain elusive. We used Affymetrix microarrays to analyze the gene expression patterns of Aire expressing cells (mature mTECs and Thymic B cells) and compared them to control counterparts, namely immature mTECs, cortical Thymic epithelial cells and splenic B cells.
Project description:We profiled medullary thymic epithelial cell subsets from a variety of conditions by scRNA-seq to investigate mechanisms of T-cell tolerance.
Project description:We have found that Cdx1 can promote ectopic gene expression in thymic epithelial cells. We isolated MHCIIhi CD80hi medullary thymic epithelial cells from Cdx1-/- and Cdx1+/+ and compare gene expression between the two subsets, also in the context of Cdx1-mediated changes in intestinal epithelial cells.
Project description:Aire is a transcriptional regulator that induces promiscuous expression of thousands of tissue-restricted antigen (TRA) genes in medullary thymic epithelial cells (mTECs). While the target genes of Aire are well characterized, the transcriptional programs regulating its own expression remain elusive. We used Affymetrix microarrays to analyze the gene expression patterns of Aire expressing cells (mature mTECs and Thymic B cells) and compared them to control counterparts, namely immature mTECs, cortical Thymic epithelial cells and splenic B cells of tissue-restricted antigen (TRA) genes in medullary thymic epithelial cells (mTECs). While the target genes of Aire are well characterized, the transcriptional programs regulating its own expression remain elusive. We’ve used Assay for transposase-accessible chromatin using sequencing (ATAC-Seq) on the different thymic epithelial cell populations to assess chromatin accessibility around the Aire locus in these cells. Moreover, we’ve used the indexing-first chromatin immunoprecipitation (iChIP) technique to assess the occupancy of the Irf8 transcription factor in the Aire locus
Project description:Aire is a transcriptional regulator that induces promiscuous expression of thousands of tissue-restricted antigen (TRA) genes in medullary thymic epithelial cells (mTECs). While the target genes of Aire are well characterized, the transcriptional programs regulating its own expression remain elusive. We used Affymetrix microarrays to analyze the gene expression patterns of Aire expressing cells (mature mTECs and Thymic B cells) and compared them to control counterparts, namely immature mTECs, cortical Thymic epithelial cells and splenic B cells of tissue-restricted antigen (TRA) genes in medullary thymic epithelial cells (mTECs). While the target genes of Aire are well characterized, the transcriptional programs regulating its own expression remain elusive. We’ve used Assay for transposase-accessible chromatin using sequencing (ATAC-Seq) on the different thymic epithelial cell populations to assess chromatin accessibility around the Aire locus in these cells. Moreover, we’ve used the indexing-first chromatin immunoprecipitation (iChIP) technique to assess the occupancy of the Irf8 transcription factor in the Aire locus
Project description:The rat thymic medulla provides the microenvironment for negative selection, late thymocyte maturation, and thymocyte egress, and is generally characterized by widespread distribution of medullary thymic epithelial cells (mTECs). In contrast, rat thymic medulla contains medullary epithelium-free areas (mEFAs), but the cellular composition and functional significance of these regions remain unclear. Here, we combined spatial transcriptomics, scRNA-seq, and robust cell-type decomposition (RCTD) to characterize mEFAs in Lewis rat thymus. These analyses revealed that mature single-positive thymocytes, including CD4SP, CD8SP, and regulatory T-cell-lineage cells, were preferentially localized in mEFAs, whereas immature SP subsets were enriched in medullary epithelium-containing areas. Rat thymic mesenchymal cell-3 and -4 (TMC3 and TMC4) subsets were also enriched in mEFAs. These subsets were broadly similar to mouse medullary fibroblasts but displayed distinct predicted interactions with SP thymocytes, including costimulatory molecule–receptor, chemokine–receptor, and ECM–integrin axes. In addition, the venous endothelial cells (vECs) expressing portal endothelial cell markers were accumulated in mEFAs. The S1P transporter gene Spns2 was preferentially expressed in both TMC4 and vEC subsets, suggesting increased local concentration in mEFAs. These findings indicate that rat mEFAs are specialized medullary niches linking stromal organization, thymocyte maturation, and thymic egress.
Project description:Thymic epithelial cells (TECs) govern thymic T lymphocyte differentiation and selection. They can be divided into cortical and medullary TECs based on their anatomical location, function and molecular features. Cortical TECs (cTECs) provide the microenvironment for the commitment of haematopoietic precursors to the T lymphoid lineage and mediate the positive selection of CD4+CD8+ double-positive thymocytes. Medullary TECs (mTECs) facilitate the negative selection of self-reactive thymocytes and the differentiation of FOXP3+ regulatory T (Treg) cells2. 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 determine the transcriptional impact of Kat7 loss, we purified mTECs and cTECs from Kat7-knockout and control mice and performed RNA-seq. The mTECs were further divided into MHCII-high and MHCII-low subsets.
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