title: Aire-expressing thymic medullary epithelial cells originate from β5t-expressing progenitor cells.
abstract: The thymus provides multiple microenvironments that are essential for the development and repertoire selection of T lymphocytes. The thymic cortex induces the generation and positive selection of T lymphocytes, whereas the thymic medulla establishes self-tolerance among the positively selected T lymphocytes. Cortical thymic epithelial cells (cTECs) and medullary TECs (mTECs) constitute the major stromal cells that structurally form and functionally characterize the cortex and the medulla, respectively. cTECs and mTECs are both derived from the endodermal epithelium of the third pharyngeal pouch. However, the molecular and cellular characteristics of the progenitor cells for the distinct TEC lineages are unclear. Here we report the preparation and characterization of mice that express the recombinase Cre instead of β5t, a proteasome subunit that is abundant in cTECs and not detected in other cell types, including mTECs. By crossing β5t-Cre knock-in mice with loxP-dependent GFP reporter mice, we found that β5t-Cre-mediated recombination occurs specifically in TECs but not in any other cell types in the mouse. Surprisingly, in addition to cTECs, β5t-Cre-loxP-mediated GFP expression was detected in almost all mTECs. These results indicate that the majority of mTECs, including autoimmune regulator-expressing mTECs, are derived from β5t-expressing progenitor cells.
authors.affiliation: Division of Experimental Immunology, Institute for Genome Research, University of Tokushima, Tokushima 770-8503, Japan.
authors.forename: Izumi
authors.initials: I
authors.lastname: Ohigashi
authors.forename: Saulius
authors.initials: S
authors.lastname: Zuklys
authors.forename: Mie
authors.initials: M
authors.lastname: Sakata
authors.forename: Carlos E
authors.initials: CE
authors.lastname: Mayer
authors.forename: Saule
authors.initials: S
authors.lastname: Zhanybekova
authors.forename: Shigeo
authors.initials: S
authors.lastname: Murata
authors.forename: Keiji
authors.initials: K
authors.lastname: Tanaka
authors.forename: Georg A
authors.initials: GA
authors.lastname: Holländer
authors.forename: Yousuke
authors.initials: Y
authors.lastname: Takahama
mesh_terms: D000818:Animals; D004847:Epithelial Cells / Q000378:metabolism*; D005434:Flow Cytometry; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D019426:Integrases / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D057507:Mice, 129 Strain; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D018613:Microscopy, Confocal; D046988:Proteasome Endopeptidase Complex / Q000235:genetics / Q000378:metabolism*; D013234:Stem Cells / Q000378:metabolism*; D013601:T-Lymphocytes / Q000378:metabolism; D013950:Thymus Gland / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism; D000096927:AIRE Protein
chemical_list: D049452:Green Fluorescent Proteins; D019426:Integrases; D046988:Proteasome Endopeptidase Complex; D014157:Transcription Factors; D000096927:AIRE Protein; C045073:Cre recombinase; C520309:proteasome subunit beta5t, mouse