Lysophosphatidic Acid Receptor 4 (LPAR4)

Competition binding and reporter gene assays showed that GPR23 preferred structural analogs of LPA with a rank order of 1-oleoyl-, followed by 1-stearoyl-, 1-palmitoyl-, 1-myristoyl-, 1-alkyl-, and 1-alkenyl-LPA. In Chinese hamster ovary cells expressing GPR23, 1-oleoyl-LPA induced an increase in intracellular Ca(2+) concentration and stimulated adenylyl cyclase activity. Granulocytic differentiation was induced by dimethylsulfoxide, and a monocytic/macrophage phenotype was induced by phorbol esters. P2Y9 was moderately expressed in undifferentiated cells. In granulocytic cells, the expression decreased to 50%, and during monocytic differentiation, P2Y9 expression increased up to 4-fold, showing distinct maxima at 12 and 48 hours of induction.