Identification of GPR55 as a Lysophosphatidylinositol Receptor

Biochem Biophys Res Commun. 2007 Nov 3;362(4):928-34. doi: 10.1016/j.bbrc.2007.08.078. Epub 2007 Aug 24.

Abstract

GPR55 is an orphan G protein-coupled receptor. In this study, we explored a possible endogenous ligand for GPR55 using HEK293 cells which expressed GPR55. We found that lysophosphatidylinositol induced rapid phosphorylation of the extracellular signal-regulated kinase in transiently or stably GPR55-expressing cells. On the other hand, lysophosphatidylinositol did not induce phosphorylation of the extracellular signal-regulated kinase in vector-transfected cells. Lysophosphatidic acid and sphingosine 1-phosphate also induced phosphorylation of the extracellular signal-regulated kinase in GPR55-expressing cells. However, these lipid phosphoric acids elicited similar responses in vector-transfected cells. Various types of other lysolipids as well as the cannabinoid receptor ligands did not induce phosphorylation of the extracellular signal-regulated kinase. We also found that lysophosphatidylinositol elicited a rapid Ca2+ transient in GPR55-expressing cells. Lysophosphatidylinositol also stimulated the binding of GTPgammaS to the GPR55-expressing cell membranes. These results strongly suggest that GPR55 is a specific and functional receptor for lysophosphatidylinositol.

MeSH terms

  • Binding Sites
  • Cell Line
  • Humans
  • Kidney / metabolism*
  • Protein Binding
  • Receptors, G-Protein-Coupled / chemistry*
  • Receptors, G-Protein-Coupled / metabolism*
  • Receptors, Lysophospholipid / chemistry*
  • Receptors, Lysophospholipid / metabolism*

Substances

  • G-protein-coupled receptor 34
  • GPR55 protein, human
  • Receptors, G-Protein-Coupled
  • Receptors, Lysophospholipid