Exploring the ‘RPRL’ Motif of Apelin‐13 through Molecular Simulation and Biological Evaluation of Cyclic Peptide Analogues

Macaluso, N. J. Maximilian; Glen, Robert C.

doi:10.1002/cmdc.201000061

Cited by 37 publications

(44 citation statements)

References 47 publications

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“…Compellingly, the conserved structural features of the apelin isoforms have been directly employed in design of peptide-based AR antagonists (Macaluso and Glen 2010;Macaluso et al 2011), and agonists (Murza et al 2012). Despite the clear importance of the apelin C-terminal dodecapeptide region, the presence of multiple apelin isoforms in the body suggests an evolutionary purpose.…”

Section: Apelin-induced Signallingmentioning

confidence: 99%

The apelin receptor: physiology, pathology, cell signalling, and ligand modulation of a peptide-activated class A GPCR

Chapman

Dupré

Rainey

2014

Biochem. Cell Biol.

176

135

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The apelin receptor (AR or APJ) is a class A (rhodopsin-like) G-protein coupled receptor (GPCR) with wide distribution throughout the human body. Activation of the AR by its cognate peptide ligand, apelin, induces diverse physiological effects including vasoconstriction and dilation; strengthening of heart muscle contractility; angiogenesis; and, regulation of energy metabolism and fluid homeostasis. Recently, another endogenous peptidic activator of the AR, Toddler/ ELABELA, was identified as having a crucial role in zebrafish embryonic development. The AR is also implicated in pathologies including cardiovascular disease, diabetes, obesity and cancer, making it a promising therapeutic target. Despite its established importance, the precise roles of AR signalling remain poorly understood. Moreover, little is known about mechanisms of peptide-AR activation. Additional complexity arises from modulation of the AR by two endogenous peptide ligands, both with multiple bioactive isoforms of variable length and distribution. The various apelin and Toddler/ELABELA isoforms may also produce distinct cellular effects. Further complexity arises through formation of functionally distinct heterodimers between the AR and other GPCRs. This minireview outlines key (patho)physiological actions of the AR, addresses what is known about signal transduction downstream of AR activation, and concludes by discussing unique properties of the endogenous peptidic ligands of the AR.

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Section: Apelin-induced Signallingmentioning

confidence: 99%

The apelin receptor: physiology, pathology, cell signalling, and ligand modulation of a peptide-activated class A GPCR

Chapman

Dupré

Rainey

2014

Biochem. Cell Biol.

176

135

View full text Add to dashboard Cite

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“…To deduce a probable bioactive conformation, we designed and synthesized conformationally constrained cyclic analogues that display high affinity for APJ. [12] These receptor probes help to confirm that a b-turn conformation at the RPRL motif is beneficial for high affinity. By using a bivalent ligand approach, we designed compounds with two 'affinity' motifs and a short series of linker groups with different conformational and nonbonded interaction properties ( Figure 5).…”

Section: Discussionmentioning

confidence: 99%

“…This was similar to the previously designed head-to-tail analogues cyclo(1-6)QRPRLS and cyclo(1-7)QRPRLSH, which had affinities of 57 and 63 % inhibition, respectively. [12] The His-Lys linker (4) displaced apelin radioligand binding by 86 %, and the reverse of this linker, Lys-His (5), exhibited 98 % inhibition. The binding of the two ligands that displayed the highest affinity, 2 and 5, were further tested at a range of concentrations to obtain K i values.…”

Section: Binding Affinitymentioning

confidence: 99%

“…Bivalent ligands can exhibit enhanced affinity by either binding to receptor dimers, or, if complementarity is favorable, by interaction with additional allosteric sites. [10] A definitive apelin pharmacophore has yet to be reported, but evidence from alanine-scanning experiments, [3,4] NMR studies, [10,11] and conformation-activity relationships derived from molecular simulations and competition binding experiments [12] suggest that the RPRL sequence is both functionally and structurally important for apelin binding. This sequence is postulated to adopt a b-turn in the receptor-bound conformation.…”

Section: Introductionmentioning

confidence: 99%

“…[4,[10][11][12] The cyclic analogue {QRPRLS}, for which curly brackets indicate an amide bond between the termini, has been shown to both promote an RPRL b-turn in molecular simulations and also to exhibit affinity at APJ. [12] This compound was a suitable candidate for the monomer unit in our design, but the absence of suitable terminal functional groups means that the inclusion of a spacer and another {QRPRLS} unit through elongation of the peptide chain is not straightforward. Instead, a similar analogue with free (carboxylic acid and amine) termini, [CRPRLC], where square brackets indicate a disulfide bridge between C1 and C6, was proposed and structurally examined through replica-exchange molecular dynamics (REMD).…”

Section: Introductionmentioning

confidence: 99%

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Discovery of a Competitive Apelin Receptor (APJ) Antagonist

et al. 2011

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The apelin receptor (APJ) is a class A G-protein-coupled receptor (GPCR) and is a putative target for the treatment of cardiovascular and metabolic diseases. Apelin-13 (NH₂-QRPRLSHKGPMPF-COOH) is a vasoactive peptide and one of the most potent endogenous inotropic agents identified to date. We report the design and discovery of a novel APJ antagonist. By using a bivalent ligand approach, we have designed compounds with two 'affinity' motifs and a short series of linker groups with different conformational and non-bonded interaction properties. One of these, cyclo(1-6)CRPRLC-KH-cyclo(9-14)CRPRLC is a competitive antagonist at APJ. Radioligand binding in CHO cells transfected with human APJ gave a K(i) value of 82 nM, competition binding in human left ventricle gave a K(D) value of 3.2 μM, and cAMP accumulation assays in CHO-K1-APJ cells gave a K(D) value of 1.32 μM.

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Stability and degradation patterns of chemically modified analogs of apelin‐13 in plasma and cerebrospinal fluid

et al. 2014

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Apelin is the endogenous ligand of APJ, which belongs to the superfamily of G protein-coupled receptors. In recent years, the apelin/APJ system has been detected in many tissues and emerges as a promising target for the treatment of various pathophysiological conditions. Pyr1-apelin-13 is the major isoform of apelin in human plasma; however its stability and proteolytic degradation pattern remain poorly understood. The aim of the present study was first to identify the cleavage sites of Pyr1-apelin-13 in mouse, rat and human plasma and rat cerebrospinal fluid, then to determine its stability to proteolytic degradation following intravenous administration in rats. Secondly, key residues were substituted by natural and unnatural amino acids in order to examine the impact on in vitro stability and degradation pattern. The kinetics of degradation revealed that the Leu5-Ser6 peptide bond of Pyr1-apelin-13 is the first cleavage observed in plasma, independently of the species. Replacement of Phe13 by unnatural amino acids showed a 10-fold increase in plasma stability although the hydrolysis of Pro12-Phe13 bond, previously described as a site of cleavage by ACE-2, was not observed. In vivo, this Pro12-Phe13 bond was cleaved yet appears as a minor product compared to hydrolysis of the Pro10-Met11 bond. This study pinpoints the most critical amino acids targeted by proteases and will be instrumental for the design of Pyr1-apelin-13 analogs possessing increased stability.

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Exploring the ‘RPRL’ Motif of Apelin‐13 through Molecular Simulation and Biological Evaluation of Cyclic Peptide Analogues

Cited by 37 publications

References 47 publications

The apelin receptor: physiology, pathology, cell signalling, and ligand modulation of a peptide-activated class A GPCR

The apelin receptor: physiology, pathology, cell signalling, and ligand modulation of a peptide-activated class A GPCR

Discovery of a Competitive Apelin Receptor (APJ) Antagonist

Stability and degradation patterns of chemically modified analogs of apelin‐13 in plasma and cerebrospinal fluid

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