title: Characterization of Lgr5-positive epithelial cells in the murine thymus.
abstract: Leucine-rich repeat-containing G protein-coupled receptor (Lgr)5 is a marker for epithelial stem cells in the adult intestine of mice. Lgr5 transcripts have also been detected in the developing murine thymus, leading to speculation that Lgr5 is a marker for the long-sought stem cell of the thymus. To address the nature of the Lgr5-expressing thymic epithelial cells (TECs), we used Lgr5-GFP reporter mice. We show that epithelial cells expressing Lgr5 protein are present in the fetal thymus during a specific developmental window yet are no longer detectable at birth. To analyze the function of the Lgr5 protein during thymus development, we generated Lgr5(-/-) mice. These experiments unequivocally show that thymus development is not perturbed in the absence of Lgr5, that all TEC subsets develop in Lgr5(-/-) mice and that T cells are produced in the expected ratios. Finally, by using an inducible lineage tracing system to track the progeny of Lgr5(+) fetal TECs in vivo, we demonstrated that Lgr5(+) fetal TECs have no detectable progeny in the later fetal thymus. In sum, we show that presence of the Lgr5 protein is not a prerequisite for proper thymus organogenesis.
authors: Department of Hematology, Erasmus University Medical Center, Rotterdam, the Netherlands.
authors: Eric
authors: E
authors: Vroegindeweij
authors: Irene
authors: I
authors: van Mourik
authors: Tom
authors: T
authors: Cupedo
authors: Jan J
authors: JJ
authors: Cornelissen
mesh_terms: D000818:Animals; D019070:Cell Lineage / Q000276:immunology; D058948:Cell Tracking; D004622:Embryo, Mammalian; D004847:Epithelial Cells / Q000166:cytology* / Q000378:metabolism; D005260:Female; D005333:Fetus; D015870:Gene Expression; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins; D051379:Mice; D008822:Mice, Transgenic; D038081:Organogenesis / Q000235:genetics* / Q000276:immunology; D011247:Pregnancy; D043562:Receptors, G-Protein-Coupled / Q000235:genetics* / Q000276:immunology; D013950:Thymus Gland / Q000166:cytology* / Q000378:metabolism
chemical_list: C493597:Lgr5 protein, mouse; D043562:Receptors, G-Protein-Coupled; D049452:Green Fluorescent Proteins