Druggable Lysophospholipid Signaling Pathways.

Lysophosphatidic acid (LPA) has major roles as a bioactive signaling molecule, with multiple physiological and pathological roles being described in almost every major organ system. In this review we discuss LPA signaling pathways as emerging drug targets for multiple conditions relevant to human health and disease. LPA signals through the six G protein-coupled receptors LPA1-6, and several of these receptors along with the LPA-producing enzyme including autotaxin (ATX) are now established as therapeutic targets with potential to treat various human diseases as exemplified by several LPA signaling targeting compounds now in clinical trials for idiopathic pulmonary fibrosis and systemic sclerosis. Several crystal structures of LPA receptors and ATX have been solved, which will accelerate development of highly selective and effective LPA signaling targeting compounds. We also review additional bioactive lysophospholipid (LPL) signaling molecules including lysophosphatidylserine and lysophosphatidylinositol, which represent the next wave of LPL druggable targets. An emerging theme in bioactive LPL signaling is that where the ligand is produced and how it is delivered to the cognate receptor are critical determinants of the biological responses. We will also discuss how connecting the production and function of bioactive LPLs will identify new therapeutic strategies to effectively target LPL signaling pathways.