title: Pharmacological and immunohistochemical characterization of the APJ receptor and its endogenous ligand apelin.
abstract: Apelin peptides have recently been identified to be the endogenous ligands for the G protein-coupled receptor APJ. However, little is known about the physiological roles of this ligand-receptor pairing. In the present study we investigated the pharmacology of several apelin analogues at the human recombinant APJ receptor using radioligand binding and functional assays. This has led to the identification of key residues in the apelin peptide required for functional potency and binding affinity through structure-activity studies. In particular, we have identified that replacement of leucine in position 5, or arginine in position 2 and 4 of the C-terminal apelin peptide, apelin-13, resulted in significant changes in pharmacology. We also investigated the detailed localization of pre-proapelin and APJ receptor mRNA in a wide range of human, rat and mouse tissues using quantitative RT-PCR, and carried out a detailed immunohistochemical study of the distribution of the APJ receptor in rat brain and spinal cord. Interestingly, the APJ receptor was not only co-localized in white matter with GFAP in the spinal cord, but was also clearly localized on neurones in the brain, suggesting that this receptor and its peptide may be involved in a wide range of biological process yet to be determined.
authors.affiliation: Neurology Centre of Excellence for Drug Discovery, GlaxoSmithKline Pharmaceuticals, Third Avenue, Harlow, Essex CM19 5AW, UK. Andy_Medhurst-1@sbphrd.com
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Medhurst
authors.forename: Carol A
authors.initials: CA
authors.lastname: Jennings
authors.forename: Melanie J
authors.initials: MJ
authors.lastname: Robbins
authors.forename: Robert P
authors.initials: RP
authors.lastname: Davis
authors.forename: Catherine
authors.initials: C
authors.lastname: Ellis
authors.forename: Kim Y
authors.initials: KY
authors.lastname: Winborn
authors.forename: Kenneth W M
authors.initials: KW
authors.lastname: Lawrie
authors.forename: Guillaume
authors.initials: G
authors.lastname: Hervieu
authors.forename: Graham
authors.initials: G
authors.lastname: Riley
authors.forename: Jane E
authors.initials: JE
authors.lastname: Bolaky
authors.forename: Nicole C
authors.initials: NC
authors.lastname: Herrity
authors.forename: Paul
authors.initials: P
authors.lastname: Murdock
authors.forename: John G
authors.initials: JG
authors.lastname: Darker
mesh_terms: D054392:Adipokines; D019943:Amino Acid Substitution; D000818:Animals; D000073861:Apelin; D000075244:Apelin Receptors; D001667:Binding, Competitive / Q000502:physiology; D015153:Blotting, Western; D001921:Brain / Q000378:metabolism; D002352:Carrier Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D005470:Fluorometry; D006801:Humans; D007150:Immunohistochemistry; D036341:Intercellular Signaling Peptides and Proteins; D008024:Ligands; D051379:Mice; D016297:Mutagenesis, Site-Directed; D009928:Organ Specificity; D011485:Protein Binding / Q000502:physiology; D011869:Radioligand Assay; D051381:Rats; D017448:Receptors, Dopamine D2 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013116:Spinal Cord / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: C115436:APLN protein, human; C104575:APLNR protein, human; D054392:Adipokines; D000073861:Apelin; D000075244:Apelin Receptors; C402826:Apln protein, mouse; C498579:Apln protein, rat; C491285:Aplnr protein, mouse; C491284:Aplnr protein, rat; D002352:Carrier Proteins; D036341:Intercellular Signaling Peptides and Proteins; D008024:Ligands; D017448:Receptors, Dopamine D2; D043562:Receptors, G-Protein-Coupled; D000242:Cyclic AMP