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-xβ), 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.
Footnotes
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This work was supported by the Associazione Italiana Ricerca sul Cancro.
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R.B. and G.N. contributed equally to this work.
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The data discussed in the article have been deposited in the National Center for Biotechnology Information's Gene Expression Omnibus (GEO; http://www.ncbi.nlm.nih.gov/geo/) and are accessible through GEO Series accession number GSE 5463.
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Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
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doi:10.1124/jpet.106.108480.
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ABBREVIATIONS: GC, glucocorticoid hormone; DPT, CD4+CD8+ double-positive thymocyte; Gpr65, G protein-coupled receptor 65; Dex, dexamethasone; FITC, fluorescein isothiocyanate; cRNA, complementary RNA; DEPC, diethyl pyrocarbonate; SAM, significance analysis of microarrays; PCR, polymerase chain reaction; Gapdh, glyceraldehyde-3-phosphate dehydrogenase; RPA, RNase protection assay; GO, Gene Ontology Consortium; ID, identification number(s); ROS, reactive oxygen species; Txnrd1, thioredoxin reductase; Txnip, thioredoxin reductase inhibitor; Ugcg, UDP-glucose ceramide glucosyltransferase; Sgpp1, sphingosine 1-phosphate phosphatase; Socs1, suppressor of cytokine signaling 1; NF, nuclear factor; Rpt801, regulated in development and damage response 1 gene; Id3, inhibitor of DNA binding 3; Dusp2, dual-specificity phosphatase 2; SEB, staphylococcal enterotoxin B.
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↵ The online version of this article (available at http://jpet.aspetjournals.org) contains supplemental material.
- Received May 28, 2006.
- Accepted August 15, 2006.
- The American Society for Pharmacology and Experimental Therapeutics
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