title: Structural and functional characterization of the interdomain interaction in the mineralocorticoid receptor.
abstract: The mineralocorticoid receptor (MR) plays a central role in electrolyte homeostasis and in cardiovascular disease. We have previously reported a ligand-dependent N/C-interaction in the MR. In the present study we sought to fully characterize the MR N/C-interaction. By using a range of natural and synthetic MR ligands in a mammalian two-hybrid assay we demonstrate that in contrast to aldosterone, which strongly induces the interaction, the physiological ligands deoxycorticosterone and cortisol weakly promote the interaction but predominantly inhibit the aldosterone-mediated N/C-interaction. Similarly, progesterone and dexamethasone antagonize the interaction. In contrast, the synthetic agonist 9alpha-fludrocortisol robustly induces the interaction. The ability of the N/C interaction to discriminate between MR agonists suggests a subtle conformational difference in the ligand-binding domain induced by these agonists. We also demonstrate that the N/C interaction is not cell specific, consistent with the evidence from a glutathione-S-transferase pull-down assay, of a direct protein-protein interaction between the N- and C-terminal domains of the MR. Examination of a panel of deletions in the N terminus suggests that several regions may be critical to the N/C-interaction. These studies have identified functional differences between physiological MR ligands, which suggest that the ligand-specific dependence of the N/C-interaction may contribute to the differential activation of the MR that has been reported in vivo.
authors.affiliation: Prince Henry's Institute of Medical Research, P.O. Box 5152, Clayton 3168, Victoria, Australia.
authors.forename: Jyotsna B
authors.initials: JB
authors.lastname: Pippal
authors.forename: Yizhou
authors.initials: Y
authors.lastname: Yao
authors.forename: Fraser M
authors.initials: FM
authors.lastname: Rogerson
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Fuller
mesh_terms: D000818:Animals; D019556:COS Cells; D002460:Cell Line; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D003900:Desoxycorticosterone / Q000737:chemistry; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D006854:Hydrocortisone / Q000494:pharmacology*; D008024:Ligands; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D051381:Rats; D018161:Receptors, Mineralocorticoid / Q000737:chemistry* / Q000378:metabolism*; D013552:Swine; D020798:Two-Hybrid System Techniques
chemical_list: D008024:Ligands; D018161:Receptors, Mineralocorticoid; D003900:Desoxycorticosterone; D005982:Glutathione Transferase; D006854:Hydrocortisone