MAGI-3 regulates LPA-induced activation of Erk and RhoA.
MAGI-3 regulates LPA-induced activation of Erk and RhoA.
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MAGI-3 调节 LPA 诱导的 Erk 和 RhoA 激活。
DOI：
10.1016/j.cellsig.2006.06.008
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发表时间：
2007
影响因子：
4.8
通讯作者：
Yun,CChris
中科院分区：
文献类型：
--
作者：
Zhang,Huanchun;Wang,Dongsheng;Sun,Hong;Hall,RandyA;Yun,CChris
溶血磷脂酸 (LPA) 通过特定的 G 蛋白偶联受体发挥多种生物效应。 LPA 激活受体亚型 LPA2 包含羧基末端基序，可与包含 PDZ 结构域的蛋白质（例如 NHERF2 和 PDZ-RhoGEF）相互作用。为了鉴定 LPA2 的其他相互作用伙伴，使用 LPA2 羧基末端筛选 PDZ 结构域的蛋白质组阵列。除了之前鉴定的 NHERF2 之外，还发现了几个额外的 LPA2 相互作用的 PDZ 结构域。其中包括 MAGI-2、MAGI-3 和神经蛋白。在目前的工作中，我们使用SW480作为细胞模型证明了LPA2和MAGI-3之间的特异性相互作用，以及MAGI-3在结肠癌细胞中的作用。 MAGI-3 特异性结合 LPA2，但不结合 LPA1 和 LPA3。这种相互作用是通过 MAGI-3 的第五个 PDZ 结构域与 LPA2 的羧基端 4 个氨基酸相互作用介导的，LPA2 的羧基端序列的突变改变严重削弱了其结合 MAGI-3 的能力。通过共亲和纯化测定，LPA2 还与细胞中的 MAGI-3 相关。 SW480 细胞中 MAGI-3 的过表达对 LPA 诱导的 Erk 和 Akt 激活没有明显影响。相反，通过 siRNA 沉默 MAGI-3 表达可显着抑制 LPA 诱导的 Erk 激活，这表明过表达缺乏作用是由于这些细胞中内源性 MAGI-3 水平较高。先前的研究表明，LPA 引发的细胞信号传导会导致 Gα12/13 以及 Gαq 依赖性途径激活小 GTP 酶 RhoA。 MAGI-3 的过度表达刺激 LPA 诱导的 RhoA 激活，而通过 siRNA 沉默 MAGI-3 会导致 RhoA 激活小幅但具有统计学意义的降低。这些结果表明MAGI-3直接与LPA2相互作用并调节LPA2激活Erk和RhoA的能力。
Lysophosphatidic acids (LPA) exert multiple biological effects through specific G protein-coupled receptors. The LPA-activated receptor subtype LPA2contains a carboxyl-terminal motif that allows interaction with PDZ domain-containing proteins, such as NHERF2 and PDZ-RhoGEF. To identify additional interacting partners of LPA2, the LPA2carboxyl-terminus was used to screen a proteomic array of PDZ domains. In addition to the previously identified NHERF2, several additional LPA2-interacting PDZ domains were found. These included MAGI-2, MAGI-3 and neurabin. In the present work, we demonstrate the specific interaction between LPA2and MAGI-3, and the effects of MAGI-3 in colon cancer cells using SW480 as a cell model. MAGI-3 specifically bound to LPA2, but not to LPA1and LPA3. This interaction was mediated via the fifth PDZ domain of MAGI-3 interacting with the carboxyl-terminal 4 amino acids of LPA2, and mutational alteration of the carboxyl-terminal sequences of LPA2severely attenuated its ability to bind MAGI-3. LPA2also associated with MAGI-3 in cells as determined by co-affinity purification. Overexpression of MAGI-3 in SW480 cells showed no apparent effect on LPA-induced activation of Erk and Akt. In contrast, silencing of MAGI-3 expression by siRNA drastically inhibited LPA-induced Erk activation, suggesting that the lack of an effect by overexpression was due to the high endogenous MAGI-3 level in these cells. Previous studies have shown that the cellular signaling elicited by LPA results in activation of the small GTPase RhoA by Gα12/13— as well as Gαq-dependent pathways. Overexpression of MAGI-3 stimulated LPA-induced RhoA activation, whereas silencing of MAGI-3 by siRNA resulted in a small but statistically significant decrease in RhoA activation. These results demonstrate that MAGI-3 interacts directly with LPA2and regulates the ability of LPA2to activate Erk and RhoA.