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Yuan XC, Tao YX. Ligands for Melanocortin Receptors: Beyond Melanocyte-Stimulating Hormones and Adrenocorticotropin. Biomolecules 2022; 12:biom12101407. [PMID: 36291616 PMCID: PMC9599618 DOI: 10.3390/biom12101407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 09/25/2022] [Accepted: 09/28/2022] [Indexed: 11/16/2022] Open
Abstract
The discovery of melanocortins in 1916 has resulted in more than 100 years of research focused on these peptides. Extensive studies have elucidated well-established functions of melanocortins mediated by cell surface receptors, including MSHR (melanocyte-stimulating hormone receptor) and ACTHR (adrenocorticotropin receptor). Subsequently, three additional melanocortin receptors (MCRs) were identified. Among these five MCRs, MC3R and MC4R are expressed primarily in the central nervous system, and are therefore referred to as the neural MCRs. Since the central melanocortin system plays important roles in regulating energy homeostasis, targeting neural MCRs is emerging as a therapeutic approach for treating metabolic conditions such as obesity and cachexia. Early efforts modifying endogenous ligands resulted in the development of many potent and selective ligands. This review focuses on the ligands for neural MCRs, including classical ligands (MSH and agouti-related peptide), nonclassical ligands (lipocalin 2, β-defensin, small molecules, and pharmacoperones), and clinically approved ligands (ACTH, setmelanotide, bremelanotide, and several repurposed drugs).
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Affiliation(s)
- Xiao-Chen Yuan
- College of Animal Science and Technology, Anhui Agricultural University, Hefei 230061, China
| | - Ya-Xiong Tao
- Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA
- Correspondence:
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2
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Melanocortin-5 Receptor: Pharmacology and Its Regulation of Energy Metabolism. Int J Mol Sci 2022; 23:ijms23158727. [PMID: 35955857 PMCID: PMC9369360 DOI: 10.3390/ijms23158727] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2022] [Revised: 07/29/2022] [Accepted: 08/03/2022] [Indexed: 12/12/2022] Open
Abstract
As the most recent melanocortin receptor (MCR) identified, melanocortin-5 receptor (MC5R) has unique tissue expression patterns, pharmacological properties, and physiological functions. Different from the other four MCR subtypes, MC5R is widely distributed in both the central nervous system and peripheral tissues and is associated with multiple functions. MC5R in sebaceous and preputial glands regulates lipid production and sexual behavior, respectively. MC5R expressed in immune cells is involved in immunomodulation. Among the five MCRs, MC5R is the predominant subtype expressed in skeletal muscle and white adipose tissue, tissues critical for energy metabolism. Activated MC5R triggers lipid mobilization in adipocytes and glucose uptake in skeletal muscle. Therefore, MC5R is a potential target for treating patients with obesity and diabetes mellitus. Melanocortin-2 receptor accessory proteins can modulate the cell surface expression, dimerization, and pharmacology of MC5R. This minireview summarizes the molecular and pharmacological properties of MC5R and highlights the progress made on MC5R in energy metabolism. We poInt. out knowledge gaps that need to be explored in the future.
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3
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Ericson MD, Doering SR, Larson CM, Freeman KT, LaVoi TM, Donow HM, Santos RG, Cho RH, Koerperich ZM, Giulianotti MA, Pinilla C, Houghten RA, Haskell-Luevano C. Functional Mixture-Based Positional Scan Identifies a Library of Antagonist Tetrapeptide Sequences (LAtTeS) with Nanomolar Potency for the Melanocortin-4 Receptor and Equipotent with the Endogenous AGRP(86-132) Antagonist. J Med Chem 2021; 64:14860-14875. [PMID: 34592820 DOI: 10.1021/acs.jmedchem.1c01417] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The melanocortin-4 receptor (MC4R) plays an important role in appetite. Agonist ligands that stimulate the MC4R decrease appetite, while antagonist compounds increase food consumption. Herein, a functional mixture-based positional scan identified novel MC4R antagonist sequences. Mixtures comprising a library of 12,960,000 tetrapeptides were screened in the presence and absence of the NDP-MSH agonist. These results led to the synthesis of 48 individual tetrapeptides, of which 40 were screened for functional activity at the melanocortin receptors. Thirteen compounds were found to possess nanomolar antagonist potency at the MC4R, with the general tetrapeptide sequence Ac-Aromatic-Basic-Aromatic-Basic-NH2. The most notable results include the identification of tetrapeptide 48 [COR1-25, Ac-DPhe(pI)-Arg-Nal(2')-Arg-NH2], an equipotent MC4R antagonist to agouti-related protein [AGRP(86-132)], more potent than miniAGRP(87-120), and possessing 15-fold selectivity for the MC4R versus the MC3R. These tetrapeptides may serve as leads for novel appetite-inducing therapies to treat states of negative energy balance, such as cachexia and anorexia.
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Affiliation(s)
- Mark D Ericson
- Department of Medicinal Chemistry and Institute for Translation Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Skye R Doering
- Department of Medicinal Chemistry and Institute for Translation Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Courtney M Larson
- Department of Medicinal Chemistry and Institute for Translation Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Katie T Freeman
- Department of Medicinal Chemistry and Institute for Translation Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Travis M LaVoi
- Florida International University, Port St. Lucie, Florida 34987, United States
| | - Haley M Donow
- Florida International University, Port St. Lucie, Florida 34987, United States
| | - Radleigh G Santos
- Nova Southeastern University, 3301 College Avenue, Fort Lauderdale, Florida 33314, United States
| | - Rachel H Cho
- Department of Medicinal Chemistry and Institute for Translation Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Zoe M Koerperich
- Department of Medicinal Chemistry and Institute for Translation Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Marc A Giulianotti
- Florida International University, Port St. Lucie, Florida 34987, United States
| | - Clemencia Pinilla
- Florida International University, Port St. Lucie, Florida 34987, United States
| | - Richard A Houghten
- Florida International University, Port St. Lucie, Florida 34987, United States
| | - Carrie Haskell-Luevano
- Department of Medicinal Chemistry and Institute for Translation Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455, United States
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4
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Malik U, Chan LY, Cai M, Hruby VJ, Kaas Q, Daly NL, Craik DJ. Development of novel frog‐skin peptide scaffolds with selectivity towards melanocortin receptor subtypes. Pept Sci (Hoboken) 2020. [DOI: 10.1002/pep2.24209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Uru Malik
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science The University of Queensland Brisbane Queensland Australia
| | - Lai Yue Chan
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science The University of Queensland Brisbane Queensland Australia
| | - Minying Cai
- Department of Chemistry and Biochemistry University of Arizona Tucson Arizona USA
| | - Victor J. Hruby
- Department of Chemistry and Biochemistry University of Arizona Tucson Arizona USA
| | - Quentin Kaas
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science The University of Queensland Brisbane Queensland Australia
| | - Norelle L. Daly
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science The University of Queensland Brisbane Queensland Australia
- Australian Institute of Tropical Health and Medicine James Cook University Cairns Queensland Australia
| | - David J. Craik
- Institute for Molecular Bioscience, Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science The University of Queensland Brisbane Queensland Australia
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5
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Yang Y, Chen M, Ventro G, Harmon CM. Key amino acid residue in Melanocortin-1 receptor (melanocyte α-MSH receptor) for ligand selectivity. Mol Cell Endocrinol 2017; 454:69-76. [PMID: 28579117 DOI: 10.1016/j.mce.2017.05.038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Revised: 05/30/2017] [Accepted: 05/30/2017] [Indexed: 11/21/2022]
Abstract
The melanocortin-1 receptor (MC1R) is a subtype of the melanocortin receptor family and NDP-α-MSH is a non-selective agonist for MC1R. The core sequence of NDP-α-MSH, His-Phe-Arg-Trp, is important for ligand binding and biological activities at the melanocortin receptor subtypes (MCRs). A recent study indicates that Trp9 in NDP-α-MSH plays an important role in ligand selectivity. Deletion of Trp9 in NDP-α-MSH (des-Trp9-NDP-α-MSH) resulted in loss of agonist activity at MC4R, although remains agonist activity at MC1R. The molecular basis for this receptor ligand selectivity is unknown. In this study we examined what region of the MC1R is responsible for des-NDP-α-MSH selectivity. Our results indicate that (1) substitution of TM3 of MC4R with the corresponding region of MC1R switches des-Trp9-NDP-α-MSH from no activity to agonist; (2) des-Trp9-NDP-α-MSH exhibits agonistic activity at the L133M mutation of the MC4R; and (3) substitution of non-conserved amino acid residue M128 in TM3 of MC1R significantly reduced des-Trp9-NDP-α-MSH agonist activity. Our results demonstrate that amino acid residue 128 in TM3 of MC1R, or amino acid residue L133 in TM3 of the MC4R, play crucial roles in ligand des-Trp9-NDP-α-MSH selectivity at MC1R or MC4R.
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Affiliation(s)
- Yingkui Yang
- Department of Surgery, State University of New York at Buffalo, Buffalo, NY 14203, United States.
| | - Min Chen
- Department of Surgery, State University of New York at Buffalo, Buffalo, NY 14203, United States
| | - George Ventro
- Department of Surgery, State University of New York at Buffalo, Buffalo, NY 14203, United States
| | - Carroll M Harmon
- Department of Surgery, State University of New York at Buffalo, Buffalo, NY 14203, United States
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Yang Y, Harmon CM. Molecular signatures of human melanocortin receptors for ligand binding and signaling. Biochim Biophys Acta Mol Basis Dis 2017; 1863:2436-2447. [PMID: 28478228 DOI: 10.1016/j.bbadis.2017.04.025] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Revised: 04/10/2017] [Accepted: 04/29/2017] [Indexed: 12/29/2022]
Abstract
Human melanocortin receptors (hMCRs) belong to the seven-transmembrane (TM) domain proteins. There are five hMCR subtypes and each of these receptor subtypes has different patterns of tissue expression and physiological function. The endogenous agonists for hMCRs are α-, β-, and γ-MSH and ACTH and endogenous antagonists are Agouti and AGRP which are the only known naturally occurring antagonists for the receptors. These peptides have their own profiles regarding the relative potency for specific hMCR subtype. Extensive studies have been performed to examine the molecular basis of the hMCRs for different ligand binding affinity and potency. Studies indicate that natural ligand α-MSH utilizes conserved amino acid residues for MCR specific binding (orthosteric binding) while synthetic ligands utilize non-conserved amino acid residues for receptor subtype specific binding (allosteric binding). ACTH is the only endogenous agonist for hMC2R and more amino acid residues at hMC2R are required for ACTH binding and signaling. HMCR computer modeling provides the detailed information of ligand and MCR interaction. This review provides the latest understanding of the molecular basis of the hMCRs for ligand binding and signaling. This article is part of a Special Issue entitled: Melanocortin Receptors - edited by Ya-Xiong Tao.
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Affiliation(s)
- Yingkui Yang
- Department of Surgery, State University of New York at Buffalo, Buffalo, NY 14203, United States.
| | - Carroll M Harmon
- Department of Surgery, State University of New York at Buffalo, Buffalo, NY 14203, United States
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7
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Van der Poorten O, Knuhtsen A, Sejer Pedersen D, Ballet S, Tourwé D. Side Chain Cyclized Aromatic Amino Acids: Great Tools as Local Constraints in Peptide and Peptidomimetic Design. J Med Chem 2016; 59:10865-10890. [PMID: 27690430 DOI: 10.1021/acs.jmedchem.6b01029] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Constraining the conformation of flexible peptides is a proven strategy to increase potency, selectivity, and metabolic stability. The focus has mostly been on constraining the backbone dihedral angles; however, the correct orientation of the amino acid side chains (χ-space) that constitute the peptide pharmacophore is equally important. Control of χ-space utilizes conformationally constrained amino acids that favor, disfavor, or exclude the gauche (-), the gauche (+), or the trans conformation. In this review we focus on cyclic aromatic amino acids in which the side chain is connected to the peptide backbone to provide control of χ1- and χ2-space. The manifold applications for cyclized analogues of the aromatic amino acids Phe, Tyr, Trp, and His within peptide medicinal chemistry are showcased herein with examples of enzyme inhibitors and ligands for G protein-coupled receptors.
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Affiliation(s)
- Olivier Van der Poorten
- Research Group of Organic Chemistry, Departments of Chemistry and Bio-Engineering Sciences, Vrije Universiteit Brussel , Pleinlaan 2, 1050 Brussels, Belgium
| | - Astrid Knuhtsen
- Department of Drug Design and Pharmacology, University of Copenhagen , Jagtvej 162, 2100 Copenhagen, Denmark
| | - Daniel Sejer Pedersen
- Department of Drug Design and Pharmacology, University of Copenhagen , Jagtvej 162, 2100 Copenhagen, Denmark
| | - Steven Ballet
- Research Group of Organic Chemistry, Departments of Chemistry and Bio-Engineering Sciences, Vrije Universiteit Brussel , Pleinlaan 2, 1050 Brussels, Belgium
| | - Dirk Tourwé
- Research Group of Organic Chemistry, Departments of Chemistry and Bio-Engineering Sciences, Vrije Universiteit Brussel , Pleinlaan 2, 1050 Brussels, Belgium
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Martin ME, O'Dorisio MS, Leverich WM, Kloepping KC, Schultz MK, Schultz MK. "Click"-cyclized (68)Ga-labeled peptides for molecular imaging and therapy: synthesis and preliminary in vitro and in vivo evaluation in a melanoma model system. Recent Results Cancer Res 2013; 194:149-75. [PMID: 22918759 PMCID: PMC3799893 DOI: 10.1007/978-3-642-27994-2_9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Cyclization techniques are used often to impart higher in vivo stability and binding affinity to peptide targeting vectors for molecular imaging and therapy. The two most often used techniques to impart these qualities are lactam bridge construction and disulfide bond formation. While these techniques have been demonstrated to be effective, orthogonal protection/deprotection steps can limit achievable product yields. In the work described in this chapter, new α-melanocyte stimulating hormone (α-MSH) peptide analogs were synthesized and cyclized by copper-catalyzed terminal azide-alkyne cycloaddition "click" chemistry techniques. The α-MSH peptide and its cognate receptor (melanocortin receptor subtype 1, MC1R) represent a well-characterized model system to examine the effect of the triazole linkage for peptide cyclization on receptor binding in vitro and in vivo. Four new DOTA-conjugated α-MSH analogs were cyclized and evaluated by in vitro competitive binding assays, serum stability testing, and in vivo imaging by positron emission tomography (PET) of tumor-bearing mice. These new DOTA-conjugated click-cyclized analogs exhibited selective high binding affinity (<2 nM) for MC1R on melanoma cells in vitro, high stability in human serum, and produced high-contrast PET/CT images of tumor xenografts. (68)Ga-labeled DOTA bioconjugates displayed rapid pharmacokinetics with receptor-mediated tumor accumulation of up to 16 ± 5% ID/g. The results indicate that the triazole ring is an effective bioisosteric replacement for the standard lactam bridge assemblage for peptide cyclization. Radiolabeling results confirm that Cu catalyst is sufficiently removed prior to DOTA chelator addition to enable insertion of radio metals or stable metals for molecular imaging and therapy. Thus, these click-chemistry-cyclized variants show promise as agents for melanocortin receptor-targeted imaging and radionuclide therapy.
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Affiliation(s)
- Molly E. Martin
- Department of Pediatric Hematology/Oncology, Carver College of Medicine, The University of Iowa
| | - M. Sue O'Dorisio
- Department of Pediatric Hematology/Oncology, Carver College of Medicine, The University of Iowa,Corresponding Author: Michael K. Schultz PhD, Departments of Radiology and Radiation Oncology (Free Radical Radiation Biology Program), Carver College of Medicine, The University of Iowa, ML B180, 500 Newton Road, Iowa City, IA 52242. Tel: +1 (319) 356-3380; Fax: +1 (319) 335-8668;
| | - Whitney M. Leverich
- Department of Pediatric Hematology/Oncology, Carver College of Medicine, The University of Iowa
| | - Kyle C. Kloepping
- Department of Radiology, Carver College of Medicine, The University of Iowa,Department of Radiation Oncology (Free Radical Radiation Biology Program), Carver College of Medicine, The University of Iowa
| | - Michael K. Schultz
- Department of Radiology, Carver College of Medicine, The University of Iowa,Department of Radiation Oncology (Free Radical Radiation Biology Program), Carver College of Medicine, The University of Iowa,Corresponding Author: Michael K. Schultz PhD, Departments of Radiology and Radiation Oncology (Free Radical Radiation Biology Program), Carver College of Medicine, The University of Iowa, ML B180, 500 Newton Road, Iowa City, IA 52242. Tel: +1 (319) 356-3380; Fax: +1 (319) 335-8668;
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9
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Access to the
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‐Fused Stereoisomers of Proline Analogues Containing an Octahydroindole Core. European J Org Chem 2011. [DOI: 10.1002/ejoc.201001710] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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10
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Mayorov AV, Cai M, Palmer ES, Liu Z, Cain JP, Vagner J, Trivedi D, Hruby VJ. Solid-phase peptide head-to-side chain cyclodimerization: discovery of C(2)-symmetric cyclic lactam hybrid α-melanocyte-stimulating hormone (MSH)/agouti-signaling protein (ASIP) analogues with potent activities at the human melanocortin receptors. Peptides 2010; 31:1894-905. [PMID: 20688117 PMCID: PMC3041174 DOI: 10.1016/j.peptides.2010.06.026] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Revised: 06/23/2010] [Accepted: 06/23/2010] [Indexed: 02/05/2023]
Abstract
A novel hybrid melanocortin pharmacophore was designed based on the pharmacophores of the agouti-signaling protein (ASIP), an endogenous melanocortin antagonist, and α-melanocyte-stimulating hormone (α-MSH), an endogenous melanocortin agonist. The designed hybrid ASIP/MSH pharmacophore was explored in monomeric cyclic, and cyclodimeric templates. The monomeric cyclic disulfide series yielded peptides with hMC3R-selective non-competitive binding affinities. The direct on-resin peptide lactam cyclodimerization yielded nanomolar range (25-120 nM) hMC1R-selective full and partial agonists in the cyclodimeric lactam series which demonstrates an improvement over the previous attempts at hybridization of MSH and agouti protein sequences. The secondary structure-oriented pharmacophore hybridization strategy will prove useful in development of unique allosteric and orthosteric melanocortin receptor modulators. This report also illustrates the utility of peptide cyclodimerization for the development of novel GPCR peptide ligands.
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Affiliation(s)
| | - Minying Cai
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, USA
| | - Erin S. Palmer
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, USA
| | - Zhihua Liu
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, USA
| | - James P. Cain
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, USA
| | - Josef Vagner
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, USA
| | - Dev Trivedi
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, USA
| | - Victor J. Hruby
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721, USA
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11
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Qu H, Cai M, Mayorov AV, Grieco P, Zingsheim M, Trivedi D, Hruby VJ. Substitution of arginine with proline and proline derivatives in melanocyte-stimulating hormones leads to selectivity for human melanocortin 4 receptor. J Med Chem 2009; 52:3627-35. [PMID: 19473029 DOI: 10.1021/jm801300c] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A new series of melanotropin analogues with His or Arg residues in the core pharmacophores of MTII, SHU9119, and Ac-NDP-gamma-MSH-NH(2) replaced by Pro or trans-/cis-4-guanidinyl-Pro derivatives were designed and synthesized to introduce selectivity toward the human melanocortin 4 receptor (hMC4R). Analogues 1, 2, 3, 6, 7, 8 were found to be hMC4R selective. Second messenger studies have demonstrated that analogues 1 and 2 are insurmountable inhibitors of MTII agonist activity at the hMC4R. Molecular modeling studies suggest that the hMC4R selectivity is due to a beta-turn shift induced by the Pro ring that makes the global minimum structures of these analogues resemble the NMR solution structure of the hASIP melanocortin receptor binding motif. Substitution of His in MTII also provided functional selectivity for the hMC3R or the hMC4R. These findings are important for a better understanding of the selectivity mechanism at the hMC3R/hMC4R and the development of therapeutic ligands selectively targeting the hMC4R.
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Affiliation(s)
- Hongchang Qu
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721, USA
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12
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Bednarek MA, MacNeil T, Tang R, Fong TM, Cabello MA, Maroto M, Teran A. Cyclic analogs of alpha-melanocyte-stimulating hormone (alphaMSH) with high agonist potency and selectivity at human melanocortin receptor 1b. Peptides 2008; 29:1010-7. [PMID: 18378043 DOI: 10.1016/j.peptides.2008.02.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2007] [Revised: 02/05/2008] [Accepted: 02/13/2008] [Indexed: 10/22/2022]
Abstract
Alpha-melanotropin (alphaMSH), Ac-Ser1-Tyr2-Ser3-Met4-Glu5-His6-Phe7-Arg8-Trp9-Gly10-Lys11-Pro12-Val13-NH2,(1) has been long recognized as an important physiological regulator of skin and hair pigmentation in mammals. Binding of this peptide to the melanocortin receptor 1 (MC1R) leads to activation of tyrosinase, the key enzyme of the melanin biosynthesis pathway. In this study, interactions of the human MC1bR (an isoform of the receptor 1a) with the synthetic cyclic analogs of alphaMSH were studied. These ligands were analogs of MTII, Ac-Nle4-cyclo-(Asp5-His6-D-Phe7-Arg8-Trp9-Lys10)-NH2, a potent pan-agonist at the human melanocortin receptors (hMC1,3-5R). In the structure of MTII, the His6-D-Phe7-Arg8-Trp9 segment has been recognized as "essential" for molecular recognition at the human melanocortin receptors (hMC1,3-5R). Herein, the role of the Trp9 in the ligand interactions with the hMC1b,3-5R has been reevaluated. Analogs with various amino acids in place of Trp9 were synthesized and tested in vitro in receptor affinity binding and cAMP functional assays at human melanocortin receptors 1b, 3, 4 and 5 (hMC1b,3-5R). Several of the new peptides were high potency agonists (partial) at hMC1bR (EC50 from 0.5 to 20 nM) and largely inactive at hMC3-5R. The bulky aromatic side chain in position 9, such as that in Trp, was found not to be essential to agonism (partial) of the studied peptides at hMC1bR.
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MESH Headings
- Binding, Competitive
- Cyclic AMP/analysis
- Cyclic AMP/biosynthesis
- Humans
- Inhibitory Concentration 50
- Molecular Structure
- Peptides, Cyclic/chemical synthesis
- Peptides, Cyclic/chemistry
- Peptides, Cyclic/isolation & purification
- Peptides, Cyclic/metabolism
- Peptides, Cyclic/pharmacology
- Receptor, Melanocortin, Type 1/agonists
- Receptor, Melanocortin, Type 1/chemistry
- Receptor, Melanocortin, Type 1/classification
- Sensitivity and Specificity
- Structure-Activity Relationship
- alpha-MSH/analogs & derivatives
- alpha-MSH/chemical synthesis
- alpha-MSH/chemistry
- alpha-MSH/isolation & purification
- alpha-MSH/metabolism
- alpha-MSH/pharmacology
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Affiliation(s)
- Maria A Bednarek
- Department of Medicinal Chemistry, Merck Research Laboratories, R50G-140, P.O. Box 2000, Rahway, NJ, USA.
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13
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Grieco P, Cai M, Liu L, Mayorov A, Chandler K, Trivedi D, Lin G, Campiglia P, Novellino E, Hruby VJ. Design and microwave-assisted synthesis of novel macrocyclic peptides active at melanocortin receptors: discovery of potent and selective hMC5R receptor antagonists. J Med Chem 2008; 51:2701-7. [PMID: 18412316 DOI: 10.1021/jm701181n] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Differentiation of the physiological role of the melanocortin receptor 5 MC5R from that of other melanocortin receptors will require development of high affinity and selective antagonists. To date, a few synthetic antagonist ligands active at hMC5 receptor are available, but most do not have appreciable selectivity. With the aim to gain more potent and selective antagonists for the MC5R ligands, we have designed, synthesized, and pharmacologically characterized a series of alkylthioaryl-bridged macrocyclic peptide analogues derived from MT-II and SHU9119. These 20-membered macrocycles were synthesized by a tandem combination using solid phase peptide synthesis and microwave-assisted reactions. Biological assays for binding affinities and adenylate cyclase activities for the hMC1R, hMC3R, hMC4R, and hMC5R showed that three analogues, compounds, 9, 4, and 7, are selective antagonists at the hMC5 receptor. In particular, compound 9(PG-20N) is a selective and competitive hMC5R antagonist, with IC 50 of 130 +/- 11 nM, and a pA 2 value of 8.3, and represents an important tool for further biological investigations of the hMC5R. Compounds 4 and 7 (PG14N, PG17N) show potent and selective allosteric inhibition at hMC5R with IC 50 values of 38 +/- 3 nM and 58 +/- 6 nM, respectively. Compound 9 will be used to further investigate and more clearly understand the physiological roles played by the MC5 receptor in humans and other animals.
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Affiliation(s)
- Paolo Grieco
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721, USA
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Mayorov AV, Cai M, Palmer ES, Dedek MM, Cain JP, Van Scoy AR, Tan B, Vagner J, Trivedi D, Hruby VJ. Structure-activity relationships of cyclic lactam analogues of alpha-melanocyte-stimulating hormone (alpha-MSH) targeting the human melanocortin-3 receptor. J Med Chem 2008; 51:187-95. [PMID: 18088090 PMCID: PMC2587288 DOI: 10.1021/jm070461w] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
A variety of dicarboxylic acid linkers introduced between the alpha-amino group of Pro(6) and the -amino group of Lys(10) of the cyclic lactam alpha-melanocyte-stimulating hormone (alpha-MSH)-derived Pro(6)-D-Phe(7)/D-Nal(2')(7)-Arg(8)-Trp(9)-Lys(10)-NH2 pentapeptide template lead to nanomolar range and selective hMC3R agonists and antagonists. Replacement of the Pro(6) residue and the dicarboxylic acid linker with 2,3-pyrazine-dicarboxylic acid furnished a highly selective nanomolar range hMC3R partial agonist (analogue 12, c[CO-2,3-pyrazine-CO-D-Phe-Arg-Trp-Lys]-NH2, EC50 = 27 nM, 70% max cAMP) and an hMC3R antagonist (analogue 13, c[CO-2,3-pyrazine-CO-D-Nal(2')-Arg-Trp-Lys]-NH2, IC50 = 23 nM). Modeling experiments suggest that 2,3-pyrazinedicarboxylic acid stabilizes a beta-turn-like structure with the D-Phe/D-Nal(2') residues, which explains the high potency of the corresponding peptides. Placement of a Nle residue in position 6 produced a hMC3R/hMC5R antagonist (analogue 15, c[CO-(CH 2)2-CO-Nle-D-Nal(2')-Arg-Trp-Lys]-NH2, IC50 = 12 and 17 nM, respectively), similarly to the previously described cyclic gamma-melanocyte-stimulating hormone (gamma-MSH)-derived hMC3R/hMC5R antagonists. These newly developed melanotropins will serve as critical biochemical tools for elucidating the full spectrum of functions performed by the physiologically important melanocortin-3 receptor.
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MESH Headings
- Binding, Competitive
- Cell Line
- Cyclic AMP/biosynthesis
- Humans
- Lactams/chemical synthesis
- Lactams/pharmacology
- Models, Molecular
- Peptides, Cyclic/chemical synthesis
- Peptides, Cyclic/chemistry
- Peptides, Cyclic/pharmacology
- Radioligand Assay
- Receptor, Melanocortin, Type 3/agonists
- Receptor, Melanocortin, Type 3/antagonists & inhibitors
- Receptor, Melanocortin, Type 3/chemistry
- Structure-Activity Relationship
- alpha-MSH/analogs & derivatives
- alpha-MSH/chemical synthesis
- alpha-MSH/pharmacology
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Affiliation(s)
| | - Minying Cai
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721
| | - Erin S. Palmer
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721
| | - Matthew M. Dedek
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721
| | - James P. Cain
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721
| | - April R. Van Scoy
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721
| | - Bahar Tan
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721
| | - Josef Vagner
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721
| | - Dev Trivedi
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721
| | - Victor J. Hruby
- Department of Chemistry, University of Arizona, Tucson, Arizona 85721
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