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Hoglin BE, Miner MV, Erbenebayar U, Shaughnessy CA, Dores RM. Trends in the evolution of the elasmobranch melanocortin-2 receptor: Insights from structure/function studies on the activation of whale shark Mc2r. Gen Comp Endocrinol 2023; 338:114278. [PMID: 36996927 DOI: 10.1016/j.ygcen.2023.114278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 02/27/2023] [Accepted: 03/25/2023] [Indexed: 03/30/2023]
Abstract
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 (H6F7R8W9) and the "address" motif (K15K16R17R18P19). Complete alanine substitution of the H6F7R8W9 motif blocked activation, whereas single alanine substitution at this motif indicated the following hierarchy of position importance for activation: W9 > R8, and substitution at F7 and H6 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 W9 > R8 = F7, (alanine substitution at H6 was negligible). Complete alanine substitution at the K15K16R17R18P19 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.
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Affiliation(s)
- Brianne E Hoglin
- University of Denver, Department of Biological Sciences, Denver, CO 80210, USA
| | - Marin V Miner
- University of Denver, Department of Biological Sciences, Denver, CO 80210, USA
| | - Ugumuur Erbenebayar
- University of Denver, Department of Biological Sciences, Denver, CO 80210, USA
| | | | - Robert M Dores
- University of Denver, Department of Biological Sciences, Denver, CO 80210, USA.
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Shaughnessy CA, Jensen MF, Dores RM. A basal actinopterygian melanocortin receptor: Molecular and functional characterization of an Mc2r ortholog from the Senegal bichir (Polypterus senegalus). Gen Comp Endocrinol 2022; 328:114105. [PMID: 35973587 DOI: 10.1016/j.ygcen.2022.114105] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 08/09/2022] [Accepted: 08/11/2022] [Indexed: 12/14/2022]
Abstract
In bony vertebrates, melanocortin 2 receptor (Mc2r) specifically binds adrenocorticotropic hormone (ACTH) and is responsible for mediating anterior pituitary signaling that stimulates corticosteroid production in the adrenal gland/interrenal cells. In bony fishes Mc2r requires the chaperoning of an accessory protein (Mrap1) to traffic to the membrane surface and bind ACTH. Here, we evaluated the structure and pharmacological properties of Mc2r from the Senegal bichir (Polypterus senegalus), which represents the most basal bony fish from which an Mc2r has been pharmacologically studied to date. In our experiments, cDNA constructs of the Mc2r from the Senegal bichir (sbMc2r) and various vertebrate Mrap1s were heterologously co-expressed in Chinese hamster ovary (CHO) cells, stimulated by ACTH or melanocyte-stimulating hormone (α-MSH) ligands, and assessed using a luciferase reporter gene assay. When expressed without an Mrap1, sbMc2r was not activated by ACTH. When co-expressed with Mrap1 from either chicken (Gallus gallus) or bowfin (Amia calva), sbMc2r could be activated in a dose-dependent manner by ACTH, but not α-MSH. Co-expression of sbMrap2 with sbMc2r resulted in no detectable activation of the receptor. Collectively, these results demonstrate that sbMc2r has pharmacological properties similar to those of Mc2rs of later-evolved bony fishes, such as Mrap1 dependence and ACTH selectivity, indicating that these qualities of Mc2r function are ancestral to all bony fish Mc2rs.
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Affiliation(s)
| | - Mary F Jensen
- Department of Biological Sciences, University of Denver, Denver, CO
| | - Robert M Dores
- Department of Biological Sciences, University of Denver, Denver, CO
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Tai X, Zhang Y, Yao J, Li X, Liu J, Han J, Lyu J, Lin G, Zhang C. Pharmacological Modulation of Melanocortin 1 Receptor Signaling by Mrap Proteins in Xenopus tropicalis. Front Endocrinol (Lausanne) 2022; 13:892407. [PMID: 35795143 PMCID: PMC9251544 DOI: 10.3389/fendo.2022.892407] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 04/27/2022] [Indexed: 11/13/2022] Open
Abstract
The melanocortin system consists of five G protein-coupled receptors (MC1R-MC5R), the bidirectional endogenous ligands (MSH and Agouti families), and accessory proteins (MRAP1 and MRAP2). Accumulative studies of vertebrate species find high expression level of melanocortin 1 receptor (MC1R) in the dermal melanocyte and elucidate the essential roles in the skin and fur pigmentation, morphological background adaptation, and stress response. The diploid amphibian Xenopus tropicalis (xt) has been utilized as a fantastic animal model for embryonic development and studies of physiological cryptic colouring and environmental adaptiveness. However, the interaction of xtMc1r signaling with xtMrap proteins has not been assessed yet. In this study, we carried out in silico evolutionary analysis of protein alignment and genetic phylogenetic and genomic synteny of mc1r among various vertebrates. Ubiquitous expression of mrap1 and mrap2 and the co-expression with mc1r transcripts in the skin were clearly observed. Co-immunoprecipitation (ip) and fluorescent complementary approach validated the direct functional interaction of xtMc1r with xtMrap1 or xtMrap2 proteins on the plasma membrane. Pharmacological assay showed the improvement of the constitutive activity and alpha melanocyte-stimulating hormone (α-MSH) stimulated plateau without dramatic alteration of the cell surface translocation of xtMc1r in the presence of xtMrap proteins. Overall, the pharmacological modulation of xtMc1r by dual xtMrap2 proteins elucidated the potential role of this protein complex in the regulation of proper dermal function in amphibian species.
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Affiliation(s)
- Xiaolu Tai
- Fundamental Research Center, Shanghai YangZhi Rehabilitation Hospital (Shanghai Sunshine Rehabilitation Center), School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Yaqun Zhang
- Department of Pathology, InnoStar Bio-tech Nantong Co., Ltd., Nantong, China
| | - Jindong Yao
- Fundamental Research Center, Shanghai YangZhi Rehabilitation Hospital (Shanghai Sunshine Rehabilitation Center), School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Xuan Li
- Fundamental Research Center, Shanghai YangZhi Rehabilitation Hospital (Shanghai Sunshine Rehabilitation Center), School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Jun Liu
- Department of Pathology, InnoStar Bio-tech Nantong Co., Ltd., Nantong, China
| | - Jiazhen Han
- Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Jianjun Lyu
- Department of Pathology, InnoStar Bio-tech Nantong Co., Ltd., Nantong, China
- *Correspondence: Jianjun Lyu, ; Gufa Lin, ; Chao Zhang,
| | - Gufa Lin
- Key Laboratory of Spine and Spinal Cord Injury Repair and Regeneration of Ministry of Education, Orthopaedic Department of Tongji Hospital, School of Life Sciences and Technology, Tongji University, Shanghai, China
- *Correspondence: Jianjun Lyu, ; Gufa Lin, ; Chao Zhang,
| | - Chao Zhang
- Fundamental Research Center, Shanghai YangZhi Rehabilitation Hospital (Shanghai Sunshine Rehabilitation Center), School of Life Sciences and Technology, Tongji University, Shanghai, China
- *Correspondence: Jianjun Lyu, ; Gufa Lin, ; Chao Zhang,
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