title: A targeted glucocorticoid receptor antisense transgene increases thymocyte apoptosis and alters thymocyte development.
abstract: The exquisite sensitivity of thymocytes to steroid-induced apoptosis, the steroidogenic potential of thymic epithelial cells, and the ability of steroid synthesis inhibitors to enhance antigen-specific deletion of thymocytes in fetal thymic organ cultures suggest a role for glucocorticoids in thymocyte development. To address this further, transgenic mice that express antisense transcripts to the glucocorticoid receptor (GR) specifically in immature thymocytes were generated. The consequent hyporesponsiveness of thymocytes to glucocorticoids was accompanied by a reduction in thymic size, primarily owing to a decrease in the number of CD4+CD8+ cells. While an enhanced susceptibility to T cell receptor (TCR)-mediated apoptosis appeared to be partially responsible for this reduction, thymocyte loss could also be detected before thymocytes progressed to the CD4+CD8+ TCR alpha beta-expressing stage. These results suggest that glucocorticoids are necessary for survival and maturation of thymocytes, and are consistent with a role for steroids in both the transition from CD4-CD8- to CD4+CD8+ cells and the survival of CD4+CD8+ cells stimulated via the TCR.
authors.affiliation: Laboratory of Immune Cell Biology, National Cancer Institute, National Institutes of Health Bethesda, Maryland 20892, USA.
authors.forename: L B
authors.initials: LB
authors.lastname: King
authors.forename: M S
authors.initials: MS
authors.lastname: Vacchio
authors.forename: K
authors.initials: K
authors.lastname: Dixon
authors.forename: R
authors.initials: R
authors.lastname: Hunziker
authors.forename: D H
authors.initials: DH
authors.lastname: Margulies
authors.forename: J D
authors.initials: JD
authors.lastname: Ashwell
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001483:Base Sequence; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D016373:DNA, Antisense / Q000032:analysis* / Q000502:physiology; D015536:Down-Regulation / Q000502:physiology; D005260:Female; D005938:Glucocorticoids / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D009924:Organ Culture Techniques; D011725:Pyridines / Q000494:pharmacology; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000187:drug effects; D011965:Receptors, Glucocorticoid / Q000187:drug effects / Q000235:genetics*; D013950:Thymus Gland / Q000166:cytology* / Q000187:drug effects / Q000196:embryology
chemical_list: D016373:DNA, Antisense; D005938:Glucocorticoids; D011725:Pyridines; D016693:Receptors, Antigen, T-Cell, alpha-beta; D011965:Receptors, Glucocorticoid; C013109:metapyrone