NHERF2 Specifically Interacts with LPA₂ Receptor and Defines the Specificity and Efficiency of Receptor-Mediated Phospholipase C-β3 Activation

Abstract

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 LPA 2 , 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 LPA 2 and the second PDZ domain of NHERF2. Moreover, the stable expression of NHERF2 potentiated LPA-induced phospholipase C-␤ (PLC-␤) activation, which was markedly attenuated by either a mutation in the PDZ-binding motif of LPA 2 or by the gene silencing of NHERF2. Using its second PDZ domain, NHERF2 was found to indirectly link LPA 2 to PLC-␤3 to form a complex, and the other PLC-␤ isozymes were not included in the protein complex. Consistently, LPA 2 -mediated PLC-␤ activation was specifically inhibited by the gene silencing of PLC-␤3. 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 LPA 2 , NHERF2, and PLC-␤3 may play a key role in the LPA 2 -mediated PLC-␤ signaling pathway.

Lysophosphatidic acid prevents apoptosis of Caco-2 colon cancer cells via activation of mitogen-activated protein kinase and phosphorylation of Bad

“…We have previously shown that knockdown of NHERF2 expression in Caco-2 cells by RNA interference drastically down-regulates the LPA 2 -Gα i -Akt pathway and induction of IL-8 [21]. Moreover, over-expression of NHERF2 reconstitutes the signaling mediated by LPA 2 [23]. Collectively these data demonstrate that displacement of the LPA 2 -NHERF2 interaction severely perturbs the cellular signaling mediated by LPA 2 .…”

“…Herein, we show that LPA provides survival signals to Caco-2 cells, protecting cells from etoposide-induced apoptosis via a NHERF2-dependent mechanism. It has previously been shown that NHERF2 interacts with LPA 2 , but not other LPA receptors, and plays a pivotal role in regulation of cellular signaling elicited by LPA 2 [21,23]. Knockdown of NHERF2 in Caco-2 and HeLa cells drastically compromised LPA 2 -mediated signaling, such as activation of Akt, Erk, and PLCβ.…”

“…LPA 2 has carboxyl-terminal motifs that allow interaction with a PDZ (PSD-95/DlgA/ZO-1) domain of the Na + /H + exchanger regulatory factor 2 (NHERF2), which functions as a scaffold to link signaling proteins, such as PKA and PKCα, to GPCRs and transporters at the cell surface [21,23,[29][30][31]. NHERF2 links LPA 2 to PLC-β3 and hence affects the activation of downstream targets, such as Erk and cyclooxygenase-2 [23]. We have previously shown that knockdown of NHERF2 expression in Caco-2 cells by RNA interference drastically down-regulates the LPA 2 -Gα i -Akt pathway and induction of IL-8 [21].…”

“…Recent studies have identified scaffold proteins that play pivotal roles in signaling elicited by LPA 2 through their interaction with the carboxyl terminus of LPA 2 . These scaffold proteins include TRIP6 and at least three PDZ (PSD-95/DlgA/ZO-1) -containing proteins, Na + /H + exchanger regulatory factor 2 (NHERF2), PDZ-RhoGEF, and leukemia-associated RhoGEF [21][22][23][24][25]. We have shown previously that knockdown of NHERF2 in Caco-2 human colon cancer cells significantly attenuated the ability of LPA 2 to induce activation of extracellular signal-regulated kinase-1/2 (Erk), Akt, and interleukin-8 (IL-8) [21].…”

Lysophospholipid signaling: Beyond the EDGs

“…All three EDG-family LPA GPCRs activate MAPK [47][48][49][50]. The transient MAPK activation observed in RH7777 cells and DKO cells in response to LPA temporally and pharmacologically resembles the cellular blebbing response; it seems likely these two processes are coupled, although the exact relationship requires further clarification.…”