Regulation of positive and negative selection and TCR signaling during thymic T cell development by capicua
Abstract
Central tolerance is achieved through positive and negative selection of thymocytes mediated by T cell receptor (TCR) signaling strength. Thus, dysregulation of the thymic selection process often leads to autoimmunity. Here, we show that Capicua (CIC), a transcriptional repressor that suppresses autoimmunity, controls the thymic selection process. Loss of CIC prior to T-cell lineage commitment impairs both positive and negative selection of thymocytes. CIC deficiency attenuated TCR signaling in CD4+CD8+ double-positive (DP) cells, as evidenced by a decrease in CD5 and phospho-ERK levels and calcium flux. We identified Spry4, Dusp4, Dusp6, and Spred1 as CIC target genes that could inhibit TCR signaling in DP cells. Furthermore, impaired positive selection and TCR signaling were partially rescued in Cic and Spry4 double mutant mice. Our findings indicate that CIC is a transcription factor required for thymic T cell development and suggests that CIC acts at multiple stages of T cell development and differentiation to prevent autoimmunity.
Data availability
The Gene Expression Omnibus (GEO) accession number for the RNA sequencing data of DP thymocytes reported in this paper is GSE173909. All data generated or analysed during this study are included in the manuscript and supporting files. Source data files have been provided for Figures 1, 2, 3, 4, 5, 6, and 7.
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RNA Sequencing Analysis of Gene Expression Profiles in WT and CIC-deficient DP ThymocytesNCBI Gene Expression Omnibus, GSE173909.
Article and author information
Author details
Funding
Samsung Science and Technology Foundation (SSTF-BA1502-14)
- Yoontae Lee
National Research Foundation of Korea (NRF-2021R1A2C3004006)
- Yoontae Lee
National Research Foundation of Korea (NRF-2017R1A5A1015366)
- Yoontae Lee
National Research Foundation of Korea (NRF-2017H1A2A1042705)
- Hyebeen Hong
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: Animal experimentation: All experiments were approved by the Institutional Animal Care and Use Committee of Pohang University of Science and Technology (POSTECH-2019-0081). All experiments were carried out in accordance with the approved guidelines. Mouse sacrifice was performed under isoflurane anesthesia, and every effort was made to minimize suffering.
Reviewing Editor
- Juan Carlos Zúñiga-Pflücker, University of Toronto, Sunnybrook Research Institute, Canada
Publication history
- Received: June 29, 2021
- Preprint posted: July 12, 2021 (view preprint)
- Accepted: December 10, 2021
- Accepted Manuscript published: December 13, 2021 (version 1)
- Version of Record published: December 23, 2021 (version 2)
Copyright
© 2021, Kim et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Further reading
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- Immunology and Inflammation
Central tolerance ensures autoreactive T cells are eliminated or diverted to the regulatory T cell lineage, thus preventing autoimmunity. To undergo central tolerance, thymocytes must enter the medulla to test their TCRs for autoreactivity against the diverse self-antigens displayed by antigen presenting cells (APCs). While CCR7 is known to promote thymocyte medullary entry and negative selection, our previous studies implicate CCR4 in these processes, raising the question of whether CCR4 and CCR7 play distinct or redundant roles in central tolerance. Here, synchronized positive selection assays, 2-photon timelapse microscopy, and quantification of TCR-signaled apoptotic thymocytes, demonstrate that CCR4 and CCR7 promote medullary accumulation and central tolerance of distinct post-positive selection thymocyte subsets in mice. CCR4 is upregulated within hours of positive selection signaling and promotes medullary entry and clonal deletion of immature post-positive selection thymocytes. In contrast, CCR7 is expressed several days later and is required for medullary localization and negative selection of mature thymocytes. In addition, CCR4 and CCR7 differentially enforce self-tolerance, with CCR4 enforcing tolerance to self-antigens presented by activated APCs, which express CCR4 ligands. Our findings show that CCR7 expression is not synonymous with medullary localization and support a revised model of central tolerance in which CCR4 and CCR7 promote early and late stages of negative selection, respectively, via interactions with distinct APC subsets.
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- Biochemistry and Chemical Biology
- Immunology and Inflammation
Genes associated with increased susceptibility to multiple sclerosis (MS) have been identified, but their functions are incompletely understood. One of these genes codes for the RNA helicase DExD/H-Box Polypeptide 39B (DDX39B), which shows genetic and functional epistasis with interleukin-7 receptor-α gene (IL7R) in MS-risk. Based on evolutionary and functional arguments, we postulated that DDX39B enhances immune tolerance thereby decreasing MS risk. Consistent with such a role we show that DDX39B controls the expression of many MS susceptibility genes and important immune-related genes. Among these we identified Forkhead Box P3 (FOXP3), which codes for the master transcriptional factor in CD4+/CD25+ T regulatory cells. DDX39B knockdown led to loss of immune-regulatory and gain of immune-effector expression signatures. Splicing of FOXP3 introns, which belong to a previously unrecognized type of introns with C-rich polypyrimidine tracts, was exquisitely sensitive to DDX39B levels. Given the importance of FOXP3 in autoimmunity, this work cements DDX39B as an important guardian of immune tolerance.