Thymopoiesis in mice depends on a Foxn1-positive thymic epithelial cell lineage

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 107; no. 38; pp. 16613 - 16618
• Main Authors: Corbeaux, Tatiana, Hess, Isabell, Swann, Jeremy B., Kanzler, Benoît, Haas-Assenbaum, Annette, Boehm, Thomas
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 21.09.2010; National Acad Sciences
• Subjects: Animal models; Animals; Base Sequence; Biological Sciences; DNA Primers - genetics; Embryonic growth stage; Embryonic Stem Cells - cytology; Embryonic Stem Cells - metabolism; Embryos; Epithelial cells; Epithelial Cells - cytology; Epithelial Cells - metabolism; Epithelium; Female; Forkhead Transcription Factors - deficiency; Forkhead Transcription Factors - genetics; Forkhead Transcription Factors - metabolism; Gene Expression Regulation, Developmental; Humans; Lymphopoiesis - genetics; Lymphopoiesis - physiology; Mice; Mice, Knockout; Mice, Transgenic; Nucleotides; Pregnancy; Progenitor cells; Proteins; Rodents; T cell receptors; T lymphocytes; Thymocytes; Thymus Gland - abnormalities; Thymus Gland - cytology; Thymus Gland - embryology; Thymus Gland - metabolism; Tissues; Transgenes; Transgenic animals
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1004623107

The thymus is essential for T-cell development. Here, we focus on the role of the transcription factor Foxn1 in the development and function of thymic epithelial cells (TECs) of the mouse. TECs are of endodermal origin; they initially express Foxn1 and give rise to orthotopic (thoracic) and additional (cervical) thymi. Using Foxn1-directed cytoablation, we show that during embryogenesis, cervical thymi develop a few days after the thoracic lobes, and that bipotent epithelial progenitors of cortical and medullary compartments express Foxn1. We also show that following acute selective near-total ablation during embryogenesis, complete regeneration of TECs does not occur, providing an animal model for human thymic aplasia syndromes. Finally, we address the functional role of Foxn1-negative TECs that arise postnatally in the mouse. Lineage tracing shows that such Foxn1-negative TECs are descendants of Foxn1-positive progenitors; furthermore, Foxn1-directed subacute intoxication of TECs by polyglutamine-containing EGFP proteins indicates that a presumptive Foxn1-independent lineage does not contribute to thymopoietic function of the adult thymus. Our findings therefore support the notion that Foxn1 is the essential transcription factor regulating the differentiation of TECs and that its expression marks the major functional lineage of TECs in embryonic and adult thymic tissue.