GPR75: Advances, Challenges in Deorphanization, and Potential as a Novel Drug Target for Disease Treatment

G protein-coupled receptor 75 (GPR75), a novel member of the rhodopsin-like G protein-coupled receptor (GPCR) family, has been identified across various tissues and organs, where it contributes to biological regulation and disease progression. Recent studies suggest potential interactions between GPR75 and ligands such as 20-hydroxyeicosatetraenoic acid (20-HETE) and C-C motif chemokine ligand 5 (CCL5/RANTES); however, its definitive endogenous ligand remains unidentified, and GPR75 is currently classified as an orphan receptor by International Union of Basic and Clinical Pharmacology (IUPHAR). Research on GPR75 deorphanization has underscored its critical roles in disease models, particularly in metabolic health, glucose regulation, and stability of the nervous and cardiovascular systems. However, the signaling pathways of GPR75 across different pathological conditions require further investigation. Importantly, ongoing studies are targeting GPR75 for drug development, exploring small molecule inhibitors, antibodies, and gene silencing techniques, positioning GPR75 as a promising GPCR target for treating related diseases. This review summarizes the recent advancements in GPR75 deorphanization research, examines its functions across tissues and systems, and highlights its links to metabolic, cardiovascular, and neurological disorders, thereby providing a resource for researchers to better understand the biological functions of this receptor.