Received for publication August 27, 2004.
Revised November 5, 2004.
Accepted for publication November 17, 2004.

Identification of endogenous glucocorticoid repressed genes differentially regulated by a glucocorticoid receptor mutant able to separate between NF-B and AP-1 repression

Abstract

Glucocorticoids are commonly used in the clinic, but long-term treatment is often associated with severe side effects. One way to reduce unwanted effects is to restrict glucocorticoid receptor (GR) signaling through defined pathways. In this study we examine endogenous target genes regulated by a GR mutant that in contrast to the wild type GR is unable to repress stimulated nuclear factor-B (NF-B) activity, while repression of activator protein-1 (AP-1) activity is maintained. This GR mutant (GR_R488Q) harbors a point mutation in the second zinc finger of the DNA binding domain. Its ability to distinguish between NF-B and AP-1 repression is defined using reporter genes regulated by both simple and natural promoters. The inability of GR_R488Q to repress NF-B was not related to its inability to activate target genes through a glucocorticoid response element. Furthermore, the discriminating property was observed in three different cell lines, suggesting that this is not a cell specific effect. These results show that different receptor surfaces or mechanisms are involved in repression of NF-B and AP-1, respectively. Interestingly, the GR_R488Q still interacted physically with NF-B. Gene expression profiling of HEK293 cells, which express the wild type GR and the GR_R488Q mutant allowed identification of endogenous genes preferentially repressed by GR interference with NF-B activity. The genes differentially regulated by GR_R488Q mutant versus the wild type GR after 2 h of treatment seem mainly to be involved in control of transcription and cell growth. At 8 h no such distinction could be seen.

Key words: Glucorticoids/Mineralocorticoids, AP-1, NFkappaB, Regulation of gene expression

This article has been cited by other articles:

				S. Sharma and A. Lichtenstein Dexamethasone-induced apoptotic mechanisms in myeloma cells investigated by analysis of mutant glucocorticoid receptors Blood, August 15, 2008; 112(4): 1338 - 1345. [Abstract] [Full Text] [PDF]

				X. Mao, A. K. Stewart, R. Hurren, A. Datti, X. Zhu, Y. Zhu, C. Shi, K. Lee, R. Tiedemann, Y. Eberhard, et al. A chemical biology screen identifies glucocorticoids that regulate c-maf expression by increasing its proteasomal degradation through up-regulation of ubiquitin Blood, December 1, 2007; 110(12): 4047 - 4054. [Abstract] [Full Text] [PDF]

				R. Newton and N. S. Holden Separating Transrepression and Transactivation: A Distressing Divorce for the Glucocorticoid Receptor? Mol. Pharmacol., October 1, 2007; 72(4): 799 - 809. [Abstract] [Full Text] [PDF]

				T. Rhen and J. A. Cidlowski Antiinflammatory action of glucocorticoids--new mechanisms for old drugs. N. Engl. J. Med., October 20, 2005; 353(16): 1711 - 1723. [Full Text] [PDF]