30 YEARS OF THE MINERALOCORTICOID RECEPTOR: Evolution of the mineralocorticoid receptor: sequence, structure and function

    1. Yoshinao Katsu2
    1. 1Division of Nephrology-Hypertension, Department of Medicine, University of California, San Diego, CA, USA
    2. 2Graduate School of Life Science, Hokkaido University, Sapporo, Japan
    1. Correspondence should be addressed to M E Baker or Y Katsu; Email: mbaker{at}ucsd.edu or ykatsu{at}sci.hokudai.ac.jp


    The mineralocorticoid receptor (MR) is descended from a corticoid receptor (CR), which has descendants in lamprey and hagfish, cyclostomes (jawless fish), a taxon that evolved at the base of the vertebrate line. A distinct MR and GR first appear in cartilaginous fishes (Chondrichthyes), such as sharks, skates, rays and chimeras. Skate MR has a strong response to corticosteroids that are mineralocorticoids and glucocorticoids in humans. The half-maximal responses (EC50s) for skate MR for the mineralocorticoids aldosterone and 11-deoxycorticosterone are 0.07 nM and 0.03 nM, respectively. EC50s for the glucocorticoids cortisol and corticosterone are 1 nM and 0.09 nM, respectively. The physiological mineralocorticoid in ray-finned fish, which do not synthesize aldosterone, is not fully understood because several 3-ketosteroids, including cortisol, 11-deoxycortisol, corticosterone, 11-deoxycorticosterone and progesterone are transcriptional activators of fish MR. Further divergence of the MR and GR in terrestrial vertebrates, which synthesize aldosterone, led to emergence of aldosterone as a selective ligand for the MR. Here, we combine sequence analysis of the CR and vertebrate MRs and GRs, analysis of crystal structures of human MR and GR and data on transcriptional activation by 3-ketosteroids of wild-type and mutant MRs and GRs to investigate the evolution of selectivity for 3-ketosteroids by the MR in terrestrial vertebrates and ray-finned fish, as well as the basis for binding of some glucocorticoids by human MR and other vertebrate MRs.

    • Received 13 April 2017
    • Accepted 3 May 2017
    • Made available online as an Accepted Preprint 3 May 2017
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