Structural and Functional Characterization of the Interdomain Interaction in the Mineralocorticoid Receptor

• Published in: Molecular endocrinology (Baltimore, Md.) Vol. 23; no. 9; pp. 1360 - 1370
• Main Authors: Pippal, Jyotsna B, Yao, Yizhou, Rogerson, Fraser M, Fuller, Peter J
• Format: Journal Article
• Language: English
• Published: United States Endocrine Society 01.09.2009; Oxford University Press; The Endocrine Society
• Subjects: Animals; Cell Line; Cell Line, Tumor; Cercopithecus aethiops; COS Cells; Desoxycorticosterone - chemistry; Glutathione Transferase - metabolism; Humans; Hydrocortisone - pharmacology; Ligands; Protein Conformation; Protein Structure, Tertiary; Rats; Receptors, Mineralocorticoid - chemistry; Receptors, Mineralocorticoid - metabolism; Swine; Two-Hybrid System Techniques
• ISSN: 0888-8809; 1944-9917
• DOI: 10.1210/me.2009-0032

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 9α-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. The ligand-specific dependence of the MR N/C-interaction may contribute to its differential activation in vivo.