scholarly journals Autoimmune regulator act in synergism with thymocyte adhesion in the control of lncRNAs in medullary thymic epithelial cells

2021 ◽  
Author(s):  
Max J Duarte ◽  
Romario S Mascarenhas ◽  
Amanda F Assis ◽  
Pedro P Tanaka ◽  
Cesar A Speck-Hernandez ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Model Systems ◽  
Thymic Epithelial Cells ◽  
Large Set ◽  
Rna Pol Ii ◽  
Pol Ii ◽  
Autoimmune Regulator ◽  
Medullary Thymic Epithelial Cells

The autoimmune regulator (Aire) gene in medullary thymic epithelial cells (mTECs) encodes the AIRE protein, which interacts with its partners within the nucleus. This Aire complex induces stalled RNA Pol II on chromatin to proceed with transcription elongation of a large set of messenger RNAs and microRNAs. Considering that RNA Pol II also transcribes long noncoding RNAs (lncRNAs), we hypothesized that Aire might be implicated in the upstream control of this RNA species. To test this, we employed a loss-of-function approach in which Aire knockout mTECs were compared to Aire wild-type mTECs for lncRNA transcriptional profiling both in vitro and in vivo model systems. RNA sequencing enables the differential expression profiling of lncRNAs when these cells adhere in vitro to thymocytes or do not adhere to them as a way to test the effect of cell adhesion. Sets of lncRNAs that are unique and that are shared in vitro and in vivo were identified. Among these, we found the Aire-dependent lncRNAs as for example, Platr28, Ifi30, Morrbid, Malat1, and Xist. This finding represents the first evidence that Aire mediates the transcription of lncRNAs in mTECs. Microarray hybridizations enabled us to observe that temporal thymocyte adhesion modulates the expression levels of such lncRNAs as Morrbid, Xist, and Fbxl12o after 36h of adhesion. This finding shows the existence of a synergistic mechanism involving a link between thymocyte adhesion, Aire, and lncRNAs in mTECs that might be important for immune self-representation.

scholarly journals miR-155 exerts posttranscriptional control of autoimmune regulator (Aire) and tissue-restricted antigen genes in medullary thymic epithelial cells

2021 ◽  
Author(s):  
Pedro P Tanaka ◽  
Ernna H Oliveira ◽  
Mayara C Machado ◽  
Max J Duarte ◽  
Amanda F Assis ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Large Scale ◽  
Interaction Analysis ◽  
Luciferase Reporter ◽  
Thymic Epithelial Cells ◽  
Posttranscriptional Control ◽  
Autoimmune Regulator ◽  
Aire Gene ◽  
Medullary Thymic Epithelial Cells

Background: The autoimmune regulator (Aire) gene is critical for the appropriate establishment of central immune tolerance. As one of the main controllers of promiscuous gene expression in the thymus, Aire promotes the expression of thousands of downstream tissue-restricted antigen (TRA) genes, cell adhesion genes and transcription factor genes in medullary thymic epithelial cells (mTECs). Despite the increasing knowledge about the role of Aire as an upstream transcriptional controller, little is known about the mechanisms by which this gene could be regulated. Results: Here, we assessed the posttranscriptional control of Aire by miRNAs. The in silico miRNA-mRNA interaction analysis predicted thermodynamically stable hybridization between the 3UTR of Aire mRNA and miR-155, which was confirmed to occur within the cellular milieu through a luciferase reporter assay. This finding enabled us to hypothesize that miR-155 might play a role as an intracellular posttranscriptional regulator of Aire mRNA. To test this hypothesis, we transfected a murine mTEC cell line with a miR-155 mimic in vitro, which reduced the mRNA and protein levels of Aire. Moreover, large-scale transcriptome analysis showed the modulation of 311 downstream mRNAs, which included 58 TRA mRNAs. Moreover, miR-155 mimic-transfected cells exhibited a decrease in their chemotaxis property compared with control thymocytes. Conclusion: Overall, the results indicate that miR-155 may posttranscriptionally control Aire mRNA as well as a crucial process by which mTECs allow migration of thymocytes through chemotaxis.

Ultrastructure of medullary thymic epithelial cells of autoimmune regulator (Aire)‐deficient mice

2009 ◽  
Vol 88 (1) ◽  
pp. 50-56 ◽  
Author(s):  
Živana Milićević ◽  
Novica M Milićević ◽  
Martti Laan ◽  
Pärt Peterson ◽  
Kai Kisand ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Thymic Epithelial Cells ◽  
Autoimmune Regulator ◽  
Medullary Thymic Epithelial Cells ◽  
Deficient Mice

scholarly journals Role of Prolactin and Growth Hormone on Thymus Physiology

1998 ◽  
Vol 6 (3-4) ◽  
pp. 317-323 ◽  
Author(s):  
Valéria De Mello-Coelho ◽  
Wilson Savino ◽  
Marie-Catherine Postel-Vinay ◽  
Mireille Dardenne
Keyword(s):  
Growth Hormone ◽  
Epithelial Cells ◽  
Cell Types ◽  
Pituitary Hormones ◽  
Thymic Epithelial Cells ◽  
Double Positive ◽  
Gh Treatment ◽  
Thymic Hormone

Intrathymic T-cell differentiation is under the control of the thymic microenvironment, which acts on maturing thymocytes via membrane as well as soluble products. Increasing data show that this process can be modulated by classical hormones, as exemplified herein by prolactin (PRL) and growth hormone (GH), largely secreted by the pituitary gland.Both PRL and GH stimulate the secretion of thymulin, a thymic hormone produced by thymic epithelial cells. Conversely, low levels of circulating thymulin parallel hypopituitary states. Interestingly, the enhancing effects of GH on thymulin seem to be mediated by insulinlike growth factor (IGF-1) since they can be abrogated with anti-IGF-1 or anti-IGF-l-receptor antibodies. The influence of PRL and GH on the thymic epithelium is pleiotropic: PRL enhancesin vivothe expression of high-molecular-weight cytokeratins and stimulatesin vitroTEC proliferation, an effect that is shared by GH and IGF-1.Differentiating T cells are also targets for the intrathymic action of PRL and GH.In vivoinoculation of a rat pituitary cell line into old rats results in restoration of the thymus, including differentiation of CD4-CD8-thymocytes into CD4+CD8+cells. Furthermore, PRL may regulate the maintenance of thymocyte viability during the double-positive stage of thymocyte differentiation.Injections of GH into aging mice increase total thymocyte numbers and the percentage of CD3-bearing cells, as well as the Concanavalin-A mitogenic response and IL-6 production by thymocytes. Interestingly, similar findings are observed in animals treated with IGF-1. Lastly, the thymic hypoplasia observed in dwarf mice can be reversed with GH treatment.In keeping with the data summarized earlier is the detection of receptors for PRL and GH on both thymocytes and thymic epithelial cells. Importantly, recent studies indicate that both cell types can produce PRL and GH intrathymically. Similarly, production of IGF-1 and expression of a corresponding receptor has also been demonstrated.In conclusion, these data strongly indicate that the thymus is physiologically under control of pituitary hormones PRL and GH. In addition to the classical endocrine pathway, paracrine and autocrine circuits are probably implicated in such control.

scholarly journals Combined transient ablation and single cell RNA sequencing reveals the development of medullary thymic epithelial cells

2020 ◽  
Author(s):  
Kristen L. Wells ◽  
Corey N. Miller ◽  
Andreas R. Gschwind ◽  
Wu Wei ◽  
Jonah D. Phipps ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Single Cell ◽  
Rna Sequencing ◽  
Expression Patterns ◽  
Critical Role ◽  
Lineage Tracing ◽  
Thymic Epithelial Cells ◽  
Single Cell Rna Sequencing ◽  
Medullary Thymic Epithelial Cells

AbstractMedullary thymic epithelial cells (mTECs) play a critical role in central immune tolerance by mediating negative selection of autoreactive T cells through the collective expression of the peripheral self-antigen compartment, including tissue-specific antigens (TSAs). Recent work has shown that gene expression patterns within the mTEC compartment are remarkably heterogenous and include multiple differentiated cell states. To further define mTEC development and medullary epithelial lineage relationships, we combined lineage tracing and recovery from transient in vivo mTEC ablation with single cell RNA-sequencing. The combination of bioinformatic and experimental approaches revealed a non-stem transit-amplifying population of cycling mTECs that preceded Aire expression. Based on our findings, we propose a branching model of mTEC development wherein a heterogeneous pool of transit-amplifying cells gives rise to Aire- and Ccl21a-expressing mTEC subsets. We further use experimental techniques to show that within the Aire-expressing developmental branch, TSA expression peaked as Aire expression decreased, implying Aire expression must be established before TSA expression can occur. Collectively, these data provide a higher order roadmap of mTEC development and demonstrate the power of combinatorial approaches leveraging both in vivo models and high-dimensional datasets.

scholarly journals Nanomaterials induce different levels of oxidative stress, depending on the used model system: Comparison of in vitro and in vivo effects

2020 ◽  
Author(s):  
Isabel Karkossa ◽  
Anne Bannuscher ◽  
Bryan Hellack ◽  
Wendel Wohlleben ◽  
Julie Laloy ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Epithelial Cells ◽  
Alveolar Macrophages ◽  
Model System ◽  
Alveolar Epithelial Cells ◽  
Model Systems ◽  
Alveolar Epithelial ◽  
Different Levels

Abstract Background The immense variety and constant development of nanomaterials (NMs) raise the demand for a facilitated risk assessment, for which knowledge on NMs mode of actions (MoAs) is required. For this purpose, a comprehensive data basis is of paramountcy that can be obtained using omics. Furthermore, the establishment of suitable in vitro test systems is indispensable to follow the 3R concept and to master the high number of NMs. In the present study, we aimed at comparing NM effects in vitro and in vivo using a multi-omics approach. We applied an integrated data evaluation strategy based on proteomics and metabolomics to four silica NMs and one titanium dioxide-based NM. For in vitro investigations, alveolar epithelial cells and alveolar macrophages were treated with different doses of NMs, and the results were compared to effects on rat lungs after short-term inhalations and instillations at varying doses with and without a recovery period.Results Since the production of reactive oxygen species (ROS) is described to be a critical biological effect of NMs, and enrichment analyses confirmed oxidative stress as a significant effect upon NM treatment in vitro in the present study, we focused on different levels of oxidative stress. Thus, we found opposite changes for proteins and metabolites that are related to the production of reduced glutathione in alveolar epithelial cells and alveolar macrophages, illustrating that NMs MoAs depend on the used model system. Interestingly, in vivo, pathways related to inflammation were affected to a greater extent than oxidative stress responses. Hence, the assignment of the observed effects to the levels of oxidative stress was different in vitro and in vivo as well. However, the overall classification of “active” and “passive” NMs was consistent in vitro and in vivo.Conclusions The consistent classification indicates both tested cell lines to be suitable for NM toxicity assessment even though the induced levels of oxidative stress strongly depend on the used model systems. Thus, the here presented results highlight that model systems need to be carefully revised to decipher the extent to which they can replace in vivo testing.

scholarly journals Proliferative arrest and rapid turnover of thymic epithelial cells expressing Aire

2007 ◽  
Vol 204 (11) ◽  
pp. 2521-2528 ◽  
Author(s):  
Daniel Gray ◽  
Jakub Abramson ◽  
Christophe Benoist ◽  
Diane Mathis
Keyword(s):  
Epithelial Cells ◽  
Flow Cytometric Analysis ◽  
Tolerance Induction ◽  
Brdu Incorporation ◽  
Thymic Epithelial Cells ◽  
High Turnover ◽  
Central Tolerance ◽  
Cross Presentation

Expression of autoimmune regulator (Aire) by thymic medullary epithelial cells (MECs) is critical for central tolerance of self. To explore the mechanism by which such a rare cell population imposes tolerance on the large repertoire of differentiating thymocytes, we examined the proliferation and turnover of Aire+ and Aire− MEC subsets through flow cytometric analysis of 5-bromo-2′deoxyuridine (BrdU) incorporation. The Aire+ MEC subset was almost entirely postmitotic and derived from cycling Aire− precursors. Experiments using reaggregate thymic organ cultures revealed the presence of such precursors among Aire− MECs expressing low levels of major histocompatibility complex class II and CD80. The kinetics of BrdU decay showed the Aire+ population to have a high turnover. Aire did not have a direct impact on the division of MECs in vitro or in vivo but, rather, induced their apoptosis. We argue that these properties strongly favor a “terminal differentiation” model for Aire function in MECs, placing strict temporal limits on the operation of any individual Aire+ MEC in central tolerance induction. We further speculate that the speedy apoptosis of Aire-expressing MECs may be a mechanism to promote cross-presentation of the array of peripheral-tissue antigens they produce.

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