title: Cardiac action of the first G protein biased small molecule apelin agonist.
abstract: Apelin peptide analogues displaying bias towards G protein signalling pathways have beneficial cardiovascular actions compared with the native peptide in humans in vivo. Our aim was to determine whether small molecule agonists could retain G protein bias. We have identified a biased small molecule, CMF-019, and characterised it in vitro and in vivo. In competition radioligand binding experiments in heart homogenates, CMF-019 bound to the human, rat and mouse apelin receptor with high affinity (pKi=8.58±0.04, 8.49±0.04 and 8.71±0.06 respectively). In cell-based functional assays, whereas, CMF-019 showed similar potency for the Gαi pathway to the endogenous agonist [Pyr(1)]apelin-13 (pD2=10.00±0.13 vs 9.34±0.15), in β-arrestin and internalisation assays it was less potent (pD2=6.65±0.15 vs 8.65±0.10 and pD2=6.16±0.21 vs 9.28±0.10 respectively). Analysis of these data demonstrated a bias of ∼400 for the Gαi over the β-arrestin pathway and ∼6000 over receptor internalisation. CMF-019 was tested for in vivo activity using intravenous injections into anaesthetised male Sprague-Dawley rats fitted with a pressure-volume catheter in the left ventricle. CMF-019 caused a significant increase in cardiac contractility of 606±112mmHg/s (p<0.001) at 500nmol. CMF-019 is the first biased small molecule identified at the apelin receptor and increases cardiac contractility in vivo. We have demonstrated that Gαi over β-arrestin/internalisation bias can be retained in a non-peptide analogue and predict that such bias will have the therapeutic benefit following chronic use. CMF-019 is suitable as a tool compound and provides the basis for design of biased agonists with improved pharmacokinetics for treatment of cardiovascular conditions such as pulmonary arterial hypertension.
authors.affiliation: Experimental Medicine and Immunotherapeutics, Addenbrooke's Hospital, University of Cambridge, UK.
authors.forename: Cai
authors.initials: C
authors.lastname: Read
authors.affiliation: School of Chemistry and Astbury Centre for Structural Biology, University of Leeds, UK.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Fitzpatrick
authors.affiliation: Experimental Medicine and Immunotherapeutics, Addenbrooke's Hospital, University of Cambridge, UK.
authors.forename: Peiran
authors.initials: P
authors.lastname: Yang
authors.affiliation: Experimental Medicine and Immunotherapeutics, Addenbrooke's Hospital, University of Cambridge, UK.
authors.forename: Rhoda E
authors.initials: RE
authors.lastname: Kuc
authors.affiliation: Experimental Medicine and Immunotherapeutics, Addenbrooke's Hospital, University of Cambridge, UK.
authors.forename: Janet J
authors.initials: JJ
authors.lastname: Maguire
authors.affiliation: Centre for Molecular Informatics, Department of Chemistry, University of Cambridge, UK; Biomolecular Medicine, Department of Surgery and Cancer, Imperial College London, London, UK.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Glen
authors.affiliation: School of Chemistry and Astbury Centre for Structural Biology, University of Leeds, UK.
authors.forename: Richard E
authors.initials: RE
authors.lastname: Foster
authors.affiliation: Experimental Medicine and Immunotherapeutics, Addenbrooke's Hospital, University of Cambridge, UK. Electronic address: apd10@medschl.cam.ac.uk.
authors.forename: Anthony P
authors.initials: AP
authors.lastname: Davenport
mesh_terms: D000597:Amino Acids, Branched-Chain / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics / Q000494:pharmacology*; D000818:Animals; D000073861:Apelin; D000075244:Apelin Receptors; D001562:Benzimidazoles / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics / Q000494:pharmacology*; D001665:Binding Sites; D001667:Binding, Competitive; D016466:CHO Cells; D002316:Cardiotonic Agents / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics / Q000494:pharmacology*; D003412:Cricetulus; D006207:Half-Life; D006352:Heart Ventricles / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000819:agonists* / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D008297:Male; D051379:Mice; D008958:Models, Molecular; D062105:Molecular Docking Simulation; D009200:Myocardial Contraction / Q000187:drug effects; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D043562:Receptors, G-Protein-Coupled / Q000819:agonists* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D040681:Structural Homology, Protein
chemical_list: C115436:APLN protein, human; C104575:APLNR protein, human; D000597:Amino Acids, Branched-Chain; D000073861:Apelin; D000075244:Apelin Receptors; C491285:Aplnr protein, mouse; C491284:Aplnr protein, rat; D001562:Benzimidazoles; C000618332:CMF-019; D002316:Cardiotonic Agents; D036341:Intercellular Signaling Peptides and Proteins; D043562:Receptors, G-Protein-Coupled; D011994:Recombinant Proteins; C586143:apelin 13, Pyr(1)-; C495199:apelin-13 peptide
keywords: Apelin; Biased agonism; Cardiovascular; G protein coupled receptor; In vivo