Biochemistry of the glucocorticoid receptor

Journal/Book: Z Rheumatol 1999; 58: 294-295. 1999;

Abstract: R. Renkawitz and M. Eggert; Institut für Genetik der Justus-Liebig-Universität Gießen The glucocorticoid receptor (GR) belongs to the large superfamily of steroid hormone receptors that are regulated by ligands. Glucocorticoids are involved in the gluconeogenesis in liver they promote the development of various organs they are necessary to control inflammatory processes and play an important role in T-cell apoptosis (Muller and Renkawitz 1991; Eggert et al. 1995). The GR is structured in three domains: the N-terminal domain containing the transactivation function 1 (AF 1) the central DNA-binding domain (DBD) and the C-terminal hormone binding domain (HBD) including a second transactivation function (AF 2). Upon binding of ligand the inactive cytoplasmic localized GR is activated and translocates to the nucleus. Hormone binding is accompanied by the dissociation of heat shock proteins that are complexed with the inactive GR a dimerization of GR molecules and a conformational change leading to the presentation of a nuclear translocation signal. The GR dimers bind to specific promoter sequences of several genes named glucocorticoid response elements (GRE) resulting in activation or inhibition of gene transcription (Beato 1989; Eggert et al. 1995; Gehring 1993). The DNA-bound GR regulates gene transcription in cooperation with other nuclear factors (interacting partners) that can be divided in three groups (Baniahmad et al. 1997): 1. nonreceptor transcription factors that are able to interact with GR and can bind to DNA (e.g. AP-1 and Stat 5; Reik et al. 1994; Stöcklin et al. 1997). 2. basal factors comprising the transcription initiation complex which are able to directly interact with GR (e.g. TBP; Almlof et al. 1998). 3. GR interacting factors (GRIP's) that cannot bind to DNA which function as coactivators or corepressors of GR-dependent transcription some of them most likely by remodelling chromatin structure (e.g. CBP and SRC-1; Kamei et al. 1996; Onate et al. 1996). ... le

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