Characterization of Apelin, the Ligand for the APJ Receptor

• Published in: Journal of neurochemistry Vol. 74; no. 1; pp. 34 - 41
• Main Authors: Lee, Dennis K., Cheng, Regina, Nguyen, Tuan, Fan, Theresa, Kariyawasam, Anula P., Liu, Yang, Osmond, Daniel H., George, Susan R., O'Dowd, Brian F.
• Format: Journal Article
• Language: English
• Published: Oxford UK Blackwell Science Ltd 01-01-2000; Blackwell
• Subjects: Amino Acid Sequence - genetics; Animals; Apelin; Apelin Receptors; APJ protein; Biological and medical sciences; Blood Pressure - drug effects; Brain - metabolism; Carrier Proteins - genetics; Carrier Proteins - metabolism; Carrier Proteins - pharmacology; Carrier Proteins - physiology; Central nervous system; Central neurotransmission. Neuromudulation. Pathways and receptors; chromosome X; CNS expression; DNA, Complementary - genetics; Drinking Behavior - drug effects; Fundamental and applied biological sciences. Psychology; G protein‐coupled receptor; Heart Rate - drug effects; Hormone; Humans; Intercellular Signaling Peptides and Proteins; Ligands; Male; Molecular Sequence Data; Neurotransmitter; preproapelin; Rats; Rats, Sprague-Dawley; Rats, Wistar; Receptors, Dopamine D2 - metabolism; Receptors, G-Protein-Coupled; RNA, Messenger - metabolism; Tissue Distribution; Vertebrates: nervous system and sense organs; Peptides; Rat; Ligand; Rodentia; Gene organization; Gene expression; Biological activity; Characterization; Vertebrata; Mammalia; Molecular cloning; G protein; Biological receptor
• ISSN: 0022-3042; 1471-4159
• DOI: 10.1046/j.1471-4159.2000.0740034.x

: The apelin peptide was recently discovered and demonstrated to be the endogenous ligand for the G protein‐coupled receptor, APJ. A search of the GenBank databases retrieved a rat expressed sequence tag partially encoding the preproapelin sequence. The GenBank search also revealed a human sequence on chromosome Xq25‐26.1, containing the gene encoding preproapelin. We have used the rat sequence to screen a rat brain cDNA library to obtain a cDNA encoding the full‐length open reading frame of rat preproapelin. This cDNA encoded a protein of 77 amino acids, sharing an identity of 82% with human preproapelin. Northern and in situ hybridization analyses revealed both human and rat apelin and APJ to be expressed in the brain and periphery. Both sequence and mRNA expression distribution analyses revealed similarities between apelin and angiotensin II, suggesting they that share related physiological roles. A synthetic apelin peptide was injected intravenously into male Wistar rats, resulting in immediate lowering of both systolic and diastolic blood pressure, which persisted for several minutes. Intraperitoneal apelin injections induced an increase in drinking behavior within the first 30 min after injection, with a return to baseline within 1 h.