Abstract

Lysophosphatidic acid (LPA) is the natural ligand for two phylogenetically distinct families of receptors (LPA_1–3, LPA_4–6) whose pathways control a variety of physiologic and pathophysiological responses. Identifying the benefit of balanced activation/repression of LPA receptors has always been a challenge because of the high lability of LPA and the limited availability of selective and/or stable agonists. In this study, we document the discovery of small benzofuran ethanolamine derivatives (called CpX and CpY) behaving as LPA_1–3 agonists. Initially found as rabbit urethra contracting agents, their elusive receptors were identified from [³⁵S]GTPγS-binding and β-arrestin2 recruitment investigations and then confirmed by [³H]CpX binding studies (urethra, hLPA_1-2 membranes). Both compounds induced a calcium response in hLPA_1–3 cells within a range of 0.4–1.5-log lower potency as compared with LPA. The contractions of rabbit urethra strips induced by these compounds perfectly matched binding affinities with values reaching the two-digit nanomolar level. The antagonist, KI16425, dose-dependently antagonized CpX-induced contractions in agreement with its affinity profile (LPA₁≥LPA₃>>LPA₂). The most potent agonist, CpY, doubled intraurethral pressure in anesthetized female rats at 3 µg/kg i.v. Alternatively, CpX was shown to inhibit human preadipocyte differentiation, a process totally reversed by KI16425. Together with original molecular docking data, these findings clearly established these molecules as potent agonists of LPA_1–3 and consolidated the pivotal role of LPA₁ in urethra/prostate contraction as well as in fat cell development. The discovery of these unique and less labile LPA_1–3 agonists would offer new avenues to investigate the roles of LPA receptors.