Project description:Analysis of the role of Hipk2 in regulating gene expression in medullary thymic epithelial cells. The whole genome gene signatures of purified mTEC subsets (CD80 low, CD80 high) from TEC-specific Hipk2 knockout mice were compared to mating wildtype control mice (floxed, Cre-). Results provide the up- or down-regulated genes, affected by the Hipk2 gene knockout. Total RNA obtained from isolated CD80 low and CD80 high mTECs of TEC-specific Hipk2 knockout mice compared to control mice mTEC subsets
Project description:Analysis of the role of Hipk2 in regulating gene expression in medullary thymic epithelial cells. The whole genome gene signatures of purified mTEC subsets (CD80 low, CD80 high) from TEC-specific Hipk2 knockout mice were compared to mating wildtype control mice (floxed, Cre-). Results provide the up- or down-regulated genes, affected by the Hipk2 gene knockout.
Project description:T cell differentiation is governed by interactions with thymic epithelial cells (TECs) and defects in this process undermine immune function and tolerance. To uncover new strategies to restore thymic function and adaptive immunity in immunodeficiency, we sought to determine the molecular mechanisms that control life and death decisions in TEC. We created a mouse model which specifically deleted the pro-survival gene Mcl1 in TEC. We found that while BCL-2 and BCL-XL were dispensable for TEC homeostasis, MCL-1 deficiency impacted on TEC as early as E15.5, resulting in early thymic atrophy and T cell lymphopenia, with near complete loss of thymic tissue by 2 months of age. MCL-1 was not necessary for TEC differentiation but was continually required for the survival of medullary TEC, including autoimmune regulator (AIRE) expressing TECs and the maintenance of overall thymic architecture. To understand the molecular mechanisms in more detail, RNA-seq profiling was undertaken of cortical and medullary thymic epithelial cells (cTECs and mTECs) from wildtype and knockout mice.
Project description:Thymic epithelial cells (TECs) support T cell development in the thymus. Cortical thymic epithelial cells (cTECs) facilitate positive selection of developing thymocytes whereas medullary thymic epithelial cells (mTECs) facilitate the deletion of self-reactive thymocytes in order to prevent autoimmunity. The mTEC compartment is highly dynamic with continuous maturation and turnover, but the genetic regulation of these processes remains poorly understood. MicroRNAs (miRNAs) are important regulators of TEC genetic programs since miRNA-deficient TECs are severely defective. However, the individual miRNAs important for TEC maintenance and function and their mechanisms of action remain unknown. Here, we demonstrate that miR-205 is highly and preferentially expressed in mTECs during both thymic ontogeny and in the postnatal thymus. This distinct expression is suggestive of functional importance for TEC biology. Genetic ablation of miR-205 in TECs, however, neither revealed a role for miR-205 in TEC function during homeostatic conditions nor during recovery from thymic stress conditions. Thus, despite its distinct expression, miR-205 on its own is largely dispensable for mTEC biology. In order to identify miRNAs differentially expressed in mTECs, we purified cortical thymic epithelial cells (cTECs), mTECs and CD45+ cells as three distinct populations and prepared RNA for microarray analysis. Thymic subsets were FACS-purified from 4-week old NOD wildtype mice. Thymi from 10-12 female mice were pooled together for stromal cell isolation for a total of 3 CD45+, 2 cTEC and 3 mTEC biologic replicates.
Project description:Thymic epithelial cells (TECs) support T cell development in the thymus. Cortical thymic epithelial cells (cTECs) facilitate positive selection of developing thymocytes whereas medullary thymic epithelial cells (mTECs) facilitate the deletion of self-reactive thymocytes in order to prevent autoimmunity. The mTEC compartment is highly dynamic with continuous maturation and turnover, but the genetic regulation of these processes remains poorly understood. MicroRNAs (miRNAs) are important regulators of TEC genetic programs since miRNA-deficient TECs are severely defective. However, the individual miRNAs important for TEC maintenance and function and their mechanisms of action remain unknown. Here, we demonstrate that miR-205 is highly and preferentially expressed in mTECs during both thymic ontogeny and in the postnatal thymus. This distinct expression is suggestive of functional importance for TEC biology. Genetic ablation of miR-205 in TECs, however, neither revealed a role for miR-205 in TEC function during homeostatic conditions nor during recovery from thymic stress conditions. Thus, despite its distinct expression, miR-205 on its own is largely dispensable for mTEC biology.
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:The zinc-finger transcription factor Ikaros (Ikzf1) modulates key gene expression programs important for hematopoietic development, and coding mutations in IKZF1 are found in patients with immunodeficiency, leukemia, and autoimmunity. While Ikaros has a well-established function in hematopoiesis, its role in other cell types is less well defined. Here, we uncover new functions for Ikaros in thymic epithelial lineage development and show that Ikzf1 expression in medullary thymic epithelial cells (mTECs) is required for both Autoimmune Regulator positive (Aire+) mTEC development and tissue-specific antigen (TSA) gene expression. Accordingly, TEC-specific deletion of Ikzf1 in mice results in a profound decrease in Aire+ mTECs, a global loss of TSA gene expression, and the development of autoimmunity. Moreover, Ikaros shapes thymic mimetic cell diversity and its deletion results in a dramatic expansion of thymic tuft cells and muscle-like mTECs and a loss of other Aire-dependent mimetic populations. Single-cell analysis reveals Ikaros modulates core transcriptional programs in TECs that correlate with the observed cellular changes. Our findings highlight a previously undescribed role for Ikaros in regulating epithelial lineage development and function, and suggest that failed thymic central tolerance could contribute to the autoimmunity seen in humans with IKZF1 mutations.
Project description:The zinc-finger transcription factor Ikaros (Ikzf1) modulates key gene expression programs important for hematopoietic development, and coding mutations in IKZF1 are found in patients with immunodeficiency, leukemia, and autoimmunity. While Ikaros has a well-established function in hematopoiesis, its role in other cell types is less well defined. Here, we uncover new functions for Ikaros in thymic epithelial lineage development and show that Ikzf1 expression in medullary thymic epithelial cells (mTECs) is required for both Autoimmune Regulator positive (Aire+) mTEC development and tissue-specific antigen (TSA) gene expression. Accordingly, TEC-specific deletion of Ikzf1 in mice results in a profound decrease in Aire+ mTECs, a global loss of TSA gene expression, and the development of autoimmunity. Moreover, Ikaros shapes thymic mimetic cell diversity and its deletion results in a dramatic expansion of thymic tuft cells and muscle-like mTECs and a loss of other Aire-dependent mimetic populations. Single-cell analysis reveals Ikaros modulates core transcriptional programs in TECs that correlate with the observed cellular changes. Our findings highlight a previously undescribed role for Ikaros in regulating epithelial lineage development and function, and suggest that failed thymic central tolerance could contribute to the autoimmunity seen in humans with IKZF1 mutations.
Project description:The zinc-finger transcription factor Ikaros (Ikzf1) modulates key gene expression programs important for hematopoietic development, and coding mutations in IKZF1 are found in patients with immunodeficiency, leukemia, and autoimmunity. While Ikaros has a well-established function in hematopoiesis, its role in other cell types is less well defined. Here, we uncover new functions for Ikaros in thymic epithelial lineage development and show that Ikzf1 expression in medullary thymic epithelial cells (mTECs) is required for both Autoimmune Regulator positive (Aire+) mTEC development and tissue-specific antigen (TSA) gene expression. Accordingly, TEC-specific deletion of Ikzf1 in mice results in a profound decrease in Aire+ mTECs, a global loss of TSA gene expression, and the development of autoimmunity. Moreover, Ikaros shapes thymic mimetic cell diversity and its deletion results in a dramatic expansion of thymic tuft cells and muscle-like mTECs and a loss of other Aire-dependent mimetic populations. Single-cell analysis reveals Ikaros modulates core transcriptional programs in TECs that correlate with the observed cellular changes. Our findings highlight a previously undescribed role for Ikaros in regulating epithelial lineage development and function, and suggest that failed thymic central tolerance could contribute to the autoimmunity seen in humans with IKZF1 mutations.