Medullary 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 in Mus musculus. 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.
RNA-seq data that support the findings of this study have been deposited in the GEO database under accession numbers GSE137699
Combined transient ablation and single cell RNA sequencing reveals the development of medullary thymic epithelial cellsNCBI Gene Expression Omnibus, GSE137699.
- Kristen L Wells
- Lars M Steinmetz
- Mark S Anderson
- Mark S Anderson
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Animal experimentation: Mice were maintained in the University of California San Francisco (UCSF) specific pathogen- free animal facility in accordance with the guidelines established by the Institutional Animal Care and Use Committee (IACUC) and Laboratory Animal Resource Center and all experimental procedures were approved by the Laboratory Animal Resource Center at UCSF. The animal protocol number associated with the study is AN180637-02B.
- Ellen A Robey, University of California, Berkeley, United States
© 2020, Wells et al.
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