NHERF2 specifically interacts with LPA₂ receptor and defines the specificity and efficiency of receptor-mediated phospholipase C-β3 activation

Lysophosphatidic acid (LPA) activates a family of cognate G protein-coupled receptors and is involved in various pathophysiological processes. However, it is not clearly understood how these LPA receptors are specifically coupled to their downstream signaling molecules. This study found that LPA₂, but not the other LPA receptor isoforms, specifically interacts with Na⁺/H⁺ exchanger regulatory factor2 (NHERF2). In addition, the interaction between them requires the C-terminal PDZ domain-binding motif of LPA₂ and the second PDZ domain of NHERF2. Moreover, the stable expression of NHERF2 potentiated LPA-induced phospholipase C-β (PLC-β) activation, which was markedly attenuated by either a mutation in the PDZ-binding motif of LPA₂ or by the gene silencing of NHERF2. Using its second PDZ domain, NHERF2 was found to indirectly link LPA₂ to PLC-β3 to form a complex, and the other PLC-β3 isozymes were not included in the protein complex. Consistently, LPA ₂-mediated PLC-β activation was specifically inhibited by the gene silencing of PLC-β3. In addition, NHERF2 increases LPA-induced ERK activation, which is followed by cyclooxygenase-2 induction via a PLC-dependent pathway. Overall, the results suggest that a ternary complex composed of LPA₂, NHERF2, and PLC-β3 may play a key role in the LPA ₂-mediated PLC-β signaling pathway.