Plasticity-related genes (PRGs/LRPs): a brain-specific class of lysophospholipid-modifying proteins

Recently, a set of five brain-specifically expressed membrane proteins, which define a novel subclass of the lipid phosphate phosphatases (LPP-)superfamily, has been identified, namely plasticity-related genes (PRGs/LRPs). The primary known significance of these genes is their involvement in regeneration processes and attenuation of effects induced by lysophosphatidic acid (LPA). LPA is key player in lysophospholipids, a hydrophilic group of lipids that have been recognized as important signaling molecules. It is a lipid mediator with a wide variety of biological actions, such as cell proliferation, migration and survival. Its extracellular effects are mediated through five distinct G-protein-coupled receptors (LPA1-5) and LPA therefore activates multiple signal transduction pathways. LPA signaling has been implicated in diverse processes, such as wound healing, brain development, vascular remodeling and tumor progression. LPA levels are controlled by enzymes that synthesize or degrade LPA and, thus, these enzymes also regulate many aspects of signaling transduction. Three LPPs and a splice variant have been demonstrated as deactivating LPA. Studies of PRGs indicate that this group of proteins may in fact serve as controllers of LPA and therefore opening the door to new therapeutic approaches.