title: Cutting edge: thymocyte-independent and thymocyte-dependent phases of epithelial patterning in the fetal thymus.
abstract: Thymic epithelial cells (TECs) in adult mice have been classified into distinct subsets based on keratin expression profiles. To explore the emergence of TEC subsets during ontogeny, we analyzed keratin 8 and keratin 5 expression at several stages of fetal development in normal C57BL/6J mice. In addition, thymic epithelial development and compartmentalization were explored in recombination-activating gene 2/common cytokine receptor gamma-chain-deficient and Ikaros-null mice that sustain early and profound blocks in thymocyte differentiation. The results demonstrate that initial patterning of the thymic epithelial compartment as defined by differential keratin expression does not depend on inductive signals from hematopoietic cells. However, thymocyte-derived signals are required during late fetal stages for continued development and maintenance of TEC subsets in the neonate and adult.
authors.affiliation: Department of Carcinogenesis, University of Texas, M. D. Anderson Cancer Center, Smithville, TX 78957, USA.
authors.forename: David B
authors.initials: DB
authors.lastname: Klug
authors.forename: Carla
authors.initials: C
authors.lastname: Carter
authors.forename: Irma B
authors.initials: IB
authors.lastname: Gimenez-Conti
authors.forename: Ellen R
authors.initials: ER
authors.lastname: Richie
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000235:genetics; D004847:Epithelial Cells / Q000166:cytology* / Q000276:immunology* / Q000378:metabolism; D005333:Fetus / Q000166:cytology* / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D051740:Ikaros Transcription Factor; D053631:Interleukin Receptor Common gamma Subunit; D007633:Keratins / Q000096:biosynthesis; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D009687:Nuclear Proteins; D020395:Receptors, Interleukin-7 / Q000172:deficiency / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology; D013601:T-Lymphocytes / Q000166:cytology* / Q000276:immunology*; D013950:Thymus Gland / Q000166:cytology* / Q000196:embryology / Q000276:immunology*; D014157:Transcription Factors / Q000172:deficiency / Q000235:genetics
chemical_list: D004268:DNA-Binding Proteins; C497239:IKZF1 protein, human; C507941:IL2RG protein, human; C507942:Il2rg protein, mouse; D053631:Interleukin Receptor Common gamma Subunit; D009687:Nuclear Proteins; C499311:RAG2 protein, human; C499308:Rag2 protein, mouse; D020395:Receptors, Interleukin-7; D014157:Transcription Factors; C064655:V(D)J recombination activating protein 2; C497238:Zfpn1a1 protein, mouse; D051740:Ikaros Transcription Factor; D007633:Keratins