title: Modulation of pro- and antiapoptotic molecules in double-positive (CD4+CD8+) thymocytes following dexamethasone treatment.
abstract: Glucocorticoids play a role in regulation of T lymphocytes homeostasis and development. In particular, glucocorticoid treatment induces massive apoptosis of CD4(+)CD8(+) double-positive (DP) thymocytes. This effect is due to many mechanisms, mainly driven by modulation of gene transcription. To find out which genes are modulated, we analyzed DP thymocytes treated for 3 h with dexamethasone (a synthetic glucocorticoid) by global gene expression profiling. Results indicate modulation of 163 genes, also confirmed by either RNase protection assay or real-time polymerase chain reaction. In particular, dexamethasone caused down-regulation of genes promoting DP thymocyte survival (e.g., Notch1, suppressor of cytokine signaling 1, and inhibitor of DNA binding 3) or modulation of genes activating cell death through the ceramide pathway (UDP-glucose ceramide glucosyltransferase, sphingosine 1-phosphate phosphatase, dihydroceramide desaturase, isoform 1, and G protein-coupled receptor 65) or through the mitochondrial machinery. Among the latter, there are Bcl-2 family members (Bim, Bfl-1, Bcl-xL, and Bcl-xbeta), genes involved in the control of redox status (thioredoxin reductase, thioredoxin reductase inhibitor, and NADP(+)-dependent isocitrate dehydrogenase) and genes belonging to Tis11 family that are involved in mRNA stability. Our study suggests that dexamethasone treatment of DP thymocytes modulates several genes belonging to apoptosis-related systems that can contribute to their apoptosis.
authors.affiliation: Dipartimento di Medicina Clinica e Sperimentale, Sezione di Farmacologia, Tossicologia e Chemioterapia, Università di Perugia, Istituto di Biotecnologie Trapiantologiche and Polo Scientifico e Didattico di Terni, Perugia, Italy.
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Bianchini
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Nocentini
authors.forename: Ludovic Tibor
authors.initials: LT
authors.lastname: Krausz
authors.forename: Katia
authors.initials: K
authors.lastname: Fettucciari
authors.forename: Stefano
authors.initials: S
authors.lastname: Coaccioli
authors.forename: Simona
authors.initials: S
authors.lastname: Ronchetti
authors.forename: Carlo
authors.initials: C
authors.lastname: Riccardi
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D015704:CD4 Antigens / Q000032:analysis*; D016827:CD8 Antigens / Q000032:analysis*; D003907:Dexamethasone / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D019254:Genes, bcl-2; D051379:Mice; D008809:Mice, Inbred C3H; D020871:RNA Stability; D017382:Reactive Oxygen Species; D013109:Sphingomyelins / Q000378:metabolism; D013601:T-Lymphocytes / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism
chemical_list: D015704:CD4 Antigens; D016827:CD8 Antigens; D017382:Reactive Oxygen Species; D013109:Sphingomyelins; D003907:Dexamethasone