Trends in the evolution of the elasmobranch melanocortin-2 receptor: Insights from structure/function studies on the activation of whale shark Mc2r.

Autor: Hoglin BE; University of Denver, Department of Biological Sciences, Denver, CO 80210, USA., Miner MV; University of Denver, Department of Biological Sciences, Denver, CO 80210, USA., Erbenebayar U; University of Denver, Department of Biological Sciences, Denver, CO 80210, USA., Shaughnessy CA; University of Denver, Department of Biological Sciences, Denver, CO 80210, USA., Dores RM; University of Denver, Department of Biological Sciences, Denver, CO 80210, USA. Electronic address: robert.dores@du.edu.
Jazyk: angličtina
Zdroj: General and comparative endocrinology [Gen Comp Endocrinol] 2023 Jul 01; Vol. 338, pp. 114278. Date of Electronic Publication: 2023 Mar 28.
DOI: 10.1016/j.ygcen.2023.114278
Abstrakt: To understand the mechanism for activation of the melanocortin-2 receptor (Mc2r) of the elasmobranch, Rhincodon typus (whale shark; ws), wsmc2r was co-expressed with wsmrap1 in CHO cells, and the transfected cells were stimulated with alanine-substituted analogs of ACTH(1-24) at the "message" motif (H 6 F 7 R 8 W 9 ) and the "address" motif (K 15 K 16 R 17 R 18 P 19 ). Complete alanine substitution of the H 6 F 7 R 8 W 9 motif blocked activation, whereas single alanine substitution at this motif indicated the following hierarchy of position importance for activation: W 9  > R 8 , and substitution at F 7 and H 6 had no effect on activation. The same analysis was done on a representative bony vertebrate Mc2r ortholog (Amia calva; bowfin; bf) and the order of position importance for activation was W 9  > R 8  = F 7 , (alanine substitution at H 6 was negligible). Complete alanine substitution at the K 15 K 16 R 17 R 18 P 19 motif resulted in distinct outcomes for wsMc2r and bfMc2r. For bfMc2r, this analog blocked activation-an outcome typical for bony vertebrate Mc2r orthologs. For wsMc2r, this analog resulted in a shift in sensitivity to stimulation of the analog as compared to ACTH(1-24) by two orders of magnitude, but the dose response curve did reach saturation. To evaluate whether the EC2 domain of wsMc2r plays a role in activation, a chimeric wsMc2r was made in which the EC2 domain was replaced with the EC2 domain from a melanocortin receptor that does not interact with Mrap1 (i.e., Xenopus tropicalis Mc1r). This substitution did not negatively impact the activation of the chimeric receptor. In addition, alanine substitution at a putative activation motif in the N-terminal of wsMrap1 did not affect the sensitivity of wsMc2r to stimulation by ACTH(1-24). Collectively, these observations suggest that wsMc2r may only have a HFRW binding site for melanocortin-related ligand which would explain how wsMc2r could be activated by either ACTH or MSH-sized ligands.
Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2023 Elsevier Inc. All rights reserved.)
Databáze: MEDLINE