Disruption of glucocorticoid receptor exon 2 yields a ligand-responsive C-terminal fragment that regulates gene expression.
Mice in which exon 2 of the glucocorticoid receptor (GR) has been disrupted [GR exon 2 knockout (GR2KO)] have been used as a model to study the requirement for this receptor in a number of biological systems. A recent report showed that these mice actually express a truncated ligand-binding GR fragment, prompting us to ask whether this mutation truly results in a glucocorticoid-insensitive phenotype. Based on cDNA microarray analysis of fetal thymocytes, we found that glucocorticoids were able to enhance or repress activation-induced gene expression in GR2KO and wild-type thymocytes to a similar degree. Moreover, although changes in gene expression induced by glucocorticoids alone were blunted, the expression of a substantial number of genes in GR2KO thymocytes was modulated by stimulation with glucocorticoids. Among these genes, as confirmed by quantitative real-time PCR, was the classic glucocorticoid-responsive gene glutamine synthetase as well as genes implicated in T cell development and function such as IL-7 receptor alpha-chain and glucocorticoid-induced leucine zipper (GIL2). Thus, the truncated C-terminal GR2KO product, which lacks the major transactivation domain, retains, to a large extent, the ability to regulate gene expression both positively and negatively in a ligand-responsive manner when expressed in vivo.
Mittelstadt
Paul R
PR
Building 10, Room 1B-40, National Institutes of Health, Bethesda, Maryland 20892.
Ashwell
Jonathan D
JD
D000818:Animals; D002478:Cells, Cultured; D003907:Dexamethasone / Q000494:pharmacology; D005091:Exons; D005786:Gene Expression Regulation / Q000187:drug effects; D005974:Glutamate-Ammonia Ligase / Q000187:drug effects / Q000235:genetics; D008024:Ligands; D051379:Mice; D018345:Mice, Knockout; D020411:Oligonucleotide Array Sequence Analysis; D011965:Receptors, Glucocorticoid / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D020395:Receptors, Interleukin-7 / Q000235:genetics; D020218:Response Elements; D013601:T-Lymphocytes / Q000502:physiology; D013950:Thymus Gland / Q000166:cytology / Q000187:drug effects / Q000196:embryology; D014157:Transcription Factors / Q000235:genetics
C498608:Dsip1 protein, mouse; D008024:Ligands; D011965:Receptors, Glucocorticoid; D020395:Receptors, Interleukin-7; D014157:Transcription Factors; C415350:interleukin-7 receptor, alpha chain; D003907:Dexamethasone; D005974:Glutamate-Ammonia Ligase