Adgrf1, also known as GPR110, PGR19, KPG_012, and hGPCR36, is an adhesion G protein-coupled receptor. It is involved in diverse biological processes such as immune regulation, lipid metabolism, and neurodevelopment. Adgrf1 can signal through multiple G protein classes and is related to pathways like cAMP and NF-κB [2,4].

In terms of immune-regulatory function, in GPR110 knockout (KO) mice, the anti-neuroinflammatory effects of synaptamide, an endogenous ligand of Adgrf1, were abolished. Synaptamide-induced reduction of LPS-or TNF-induced inflammatory responses in wild-type mice was not seen in KO mice. In microglia, synaptamide increased cAMP and inhibited pro-inflammatory cytokine expression in a GPR110-dependent manner [1]. Regarding liver metabolism, in diet-induced obese mice, manipulation of hepatic Adgrf1 expression showed that its level was directly correlated to liver fat content. RNA-sequencing analysis identified Scd1 as a downstream target of Adgrf1, and treatment with Scd1 inhibitors improved hepatic steatosis in Adgrf1-overexpressing mice [3].

In conclusion, Adgrf1 has crucial functions in immune-regulation and hepatic lipid metabolism. The use of Adgrf1 KO mouse models has been instrumental in revealing its role in neuroinflammation and non-alcoholic fatty liver disease, providing potential therapeutic targets for these disease areas.