Apelin receptor (APJ)

The Apelin receptor is a class A G protein-coupled receptor primarily activated by endogenous peptide ligands such as apelin isoforms and elabela. It plays critical roles in cardiovascular regulation—including blood pressure control, cardiac contractility enhancement, and fluid homeostasis—as well as vascular development. The human apelin receptor consists of 380 amino acids with seven transmembrane domains typical of GPCRs. It mediates its physiological effects through both G-protein-dependent inhibition of adenylate cyclase activity and β-arrestin-mediated pathways. The system has broad implications across multiple diseases including heart failure, hypertension, respiratory disorders like pulmonary arterial hypertension or ARDS, sepsis—where it exerts protective anti-inflammatory actions—and certain cancers such as non-small cell lung cancer or infantile hemangioma. Both small molecule modulators and peptide analogs targeting this pathway are under investigation for therapeutic use. Due to its pleiotropic functions across organ systems—and involvement in key pathophysiological processes—the apelin/APJ system represents an important emerging therapeutic target but also poses challenges related to specificity of action and potential systemic side effects.

Other names

APJAPLNRAngiotensin receptor-like 1Apelin G protein-coupled receptor

Agonists activate the apelin receptor to stimulate G-protein signaling pathways that regulate cardiovascular function and fluid balance. Antagonists block these effects by inhibiting ligand binding or downstream signaling. Some compounds exhibit biased signaling by preferentially activating either G-protein or β-arrestin pathways.